INVESTIGATING SEED DISPERSAL AND SEED BANK DYNAMICS IN
HAWAIIAN MESIC FOREST COMMUNITIES
A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI'I IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
IN
BOTANICAL SCIENCES (BOTANY)
MAY 2005
By Ane c.L. Bakutis
Thesis Committee:
Donald Drake, Chairperson Clifford Morden Tamara Ticktin ACKNOWLEDGEMENTS
I would like to thank the Hawaii Conservation Alliance for providing funding for my research; Trae Menard, Dan Sailor and Pauline Sato at the Nature Conservancy of
Hawaii, O'ahu Program for providing access to my study site in the Nature Conservancy
Honouliuli Preserve. I thank my thesis committee chair, Don Drake, and my committee members, CliffMorden and Tamara Ticktin for providing me with guidance and assistance during all stages ofmy thesis research. I thank my research assistant, Hina
Kneubuhl and the many friends and colleagues for providing me with necessary field assistance. I especially thank my family and 'family offriends' for providing me with support during my entire graduate experience.
111 TABLE OF CONTENTS
ACKNOWLEDGEMENTS 111
LIST OF TABLES V
LIST OF FIGURES VIII
CHAPTERI. INTRODUCTION 1 Seed Dispersal , 5 Seed Bank '" 7 Seed Size 8 Lack ofRecruitment 9 Questions and Hypotheses 11
CHAPTER 2. PATTERNS OF SEED DISPERSAL. 13 Introduction 13 Seed Size 14 Lack ofRecruitment ,, 14 Methods 16 Study Site 16 Description ofVegetation 19 Measurement ofSeed Rain Under Native Canopy, Edge and Alien Canopy 21 Seed Dispersal Analysis 24 Seed Size Measurements 25 Characterization ofVegetation 26 Results 27 Seed Rain , '" , 27 Seed Size and Dispersal. 40 Discussion 47 Conclusion 54
CHAPTER 3: SEED BANK DYNAMICS 55 Introduction , 55 Seed Size , 56 Lack ofRecruitment 56 Methods 57 Study Site '" 57 Measurements ofSeed Banks under Native Canopy, Alien Canopy and along the Edge 61 Seed Bank Analysis 63 Seed Size Measurements 63 Results 65 Soil Seed Bank , 65 Seed Size and Soil Seed Bank Dynamics 76
IV Disscussion """ ", 80
CHAPTER 4: SYNTHESIS 84
APPENDIX A: CHARATERIZATION OF THE VEGETATION OF KALUA'A DRAINAGE STUDY SITE 91
APPENDIX B: PHENOLOGY OF THE VEGETATION OF KALUA'A DRAINAGE STUDY SITE 105
LITERATURE CITED 128
v LIST OF TABLES
Table 2.1. Mean number ofseeds contained in 15 fruits for each species 23
Table 2.2. Abundance and percentage oftotal seed rain (Abs. = absolute, 2 % = percentage) and mean density (seeds/m ) (mean == mean seed density, % = percentage) in native, edge and alien vegetation types for all species collected in 184 seed traps in Kalua'a drainage from June 2003 to May 2004 28
2 Table 2.3. Relative mean density (seeds/m ) of 'not-dispersed' (Not-disp.) and 'dispersed' (Disp.) seed in total seed rain in all vegetation types and mean density 2 2 (seeds/m ) and relative mean density (seeds/m ) ofdispersed seed per seed trap (mean seed density = mean; relative mean density = ReI. %) in native, edge and alien vegetation and percentage oftotal dispersed seed at Kalua'a from June 2003 to May 2004 : 33
Table 2.4.. Mean density (seeds/m2 ± SE) ofdispersed seed from canopy tree species and all species by dispersal vector collected in all seed traps in Kalua'a from June 2003 to May 2004 37
Table 2.5. Relative frequency of seedlings ofall species found in the seed rain in native, edge and alien vegetation types in Kalua'a drainage. Native species are marked with an asterisk (*). (n = 30 for each forest type; n == 90 for all forest types) 39
Table 2.6. Relative mean density of 'dispersed' and 'not-dispersed' small and large seed in all vegetation types and mean density (seeds/m2 ± 1 SE) ofdispersed seed per seed trap and percentage oftotal dispersed seed from 184 seed traps in native, edge and alien vegetation at Kalua'a from June 2003 to May 2004 .41
Table 2.7. Mean (± 1 SE) seed (diaspore) mass (mg), seed length (mm) and width (mm) ofall species collected in the seed rain at Kalua'a drainage from June 2003 to May 2004 ...... 42
Table 2.8. Mean density (seeds/m2 ± 1 SE) ofdispersed seed dispersal vector collected in all seed traps in Kalua'a from June 2003 to May 2004 .45
vi Table 3.1. Relative mean density and mean density ofseedlings per soil core in native, edge and alien vegetation and percentage oftotal seedling presence for all species collected in 184 soil seed cores in Kalua'a drainage from September 2003 to June 2004 67
Table 3.2. Mean species richness per soil seed core in the native, edge and alien vegetation types 70
Table 3.3. Mean density ofgerminated seedlings per soil core in native, edge and alien vegetation for 184 soil seed cores in Kalua'a drainage from September 2003 to June 2004 76
Table 3.4. Mean seed mass (mg), seed length (mm) and width (mm) ofall species emerged from soil cores at Kalua'a drainage from June 2003 to May 2004 77
Table A.I. Abundance (Abs.= absolute abundance and %= relative cover) ofall vegetation and ground vegetation «2-m height) all three vegetation types (native, edge, alien) at Kalua'a drainage study site 92
Table A.2. Abundance (Abs.= absolute abundance and %= relative cover) ofcanopy vegetation (>2-m in height) in the three vegetation types (native, edge, alien) at Kalua'a drainage study site 98
Table A.3. Plant species present with the entire study area bounded by transects at Kalua'a drainage 100
Table B.l. Monthly percentage ofnative species with mature fruit. 106
Table B.2. Monthly percentage ofalien species with mature fruit l 07
Table B.3. Mean monthly percentage ofstems with immature fruit by native species 108
Table B.4. Mean monthly percentage ofstems with immature fruit by alien species 110
Table B.5. Mean monthly percentage ofstems with mature fruit by native tree species 112
Table B.6. Mean monthly percentage ofstems with mature fruit by alien species 114
VB LIST OF FIGURES
Figure 2.1. Study area within Kalua'a drainage, Honouliuli Preserve, The Nature Conservancy ofHawaii , .17
Figure 2.2. Diagram oftransect design 21
Figure 2.3. Percentage ofseed rain for native and alien species in the different vegetation types in Kalua'a drainage from June 2003 to May 2004 30
Figure 2.4. Percentage ofdispersed seed for native and alien species in the different vegetation types in Kalua'a drainage from June 2003 to May 2004 35
Figure 2.5. Mean density ofseeds dispersed per seed trap from native and alien species in three vegetation types at Kalua'a 35
Figure 2.6. Proportion ofdispersed seed (seed density per vegetation type/seed density from all vegetation types) from native and alien species in Kalua'a drainage from June 2003 to May 2004. . 36
Figure 2.7. Seed size distributions for dispersed seed in Kalua'a drainage from June 2003 to May 2004 by seed size .41
2 Figure 2.8. Seed mass (mg) and mean seed density (seeds/m ) in the dispersed seed rain ofnative (+) and alien (0) species .43
2 2 Figure 2.9. Seed area (m ) and mean seed density (seeds/m ) in the dispersed seed rain ofnative (+) and alien (0) species .43
Figure 2.10. Seed size distributions for bird-, wind-, gravity-, adhesion-dispersed seeds in Kalua'a drainage from June 2003 to May 2004 .45
2 Figure 2.11. Seed mass (mg) and mean seed density (seeds/m ) in the bird-dispersed seed rain ofnative (+) and alien (0) species .46
2 Figure 2.12. Seed width (mm) and mean seed density (seeds/m ) in the bird-dispersed seed rain ofnative (+) and alien (0) species .46
2 Figure 2.13. Seed length (mm) and mean seed density (seeds/m ) in the bird-dispersed seed rain ofnative (+) and alien (0) species .47
Figure 3.1. Study area within Kalua'a drainage, Honouliuli Preserve, The Nature Conservancy ofHawaii 59
Figure 3.2. Soil core design 62
V111 Figure 3.3. Percentage ofemerged seedlings for native and alien species in different vegetation types in Kalua'a drainage from June 2003 to May 2004 69
Figure 3.4. Mean density ofseedlings from native and alien species in Kalua'a drainage from June 2003 to May 2004 69
Figure 3.5. Seed profiles for species in a dry-mesic Hawaiian forest with persistent seed banks 72
Figure 3.6. Seed profiles for species in a dry-mesic Hawaiian forest with pseudo-persistent seed banks 73
Figure 3.7. Seed profiles for species in a dry-mesic Hawaiian forest with transient seed banks 74
Figure 3.8. Summary data for seed profiles for native and alien species in a dry-mesic Hawaiian forest. 75
Figure 3.9. Summary data for seed profiles for small- and large-seeded species in a dry-mesic Hawaiian forest.. 79
Figure A.I. Relative percent cover ofcanopy tree species and open sky in the native vegetation at Kalua'a drainage 103
Figure A.2. Relative percent cover ofcanopy tree species and open sky in the alien vegetation at Kalua'a drainage 103
Figure A.3. Relative percent cover ofcanopy tree species and open sky in the edge vegetation at Kalua'a drainage l 04
Figure B.l. Monthly percentage offleshy-fruited native species with mature fruit 116
Figure B.2. Monthly percentage offleshy-fruited native species with mature fruit 116
Figure B.3. Monthly percentage offleshy-fruited alien species with mature fruit...... 117
Figure B.4. Monthly percentage offleshy-fruited alien species with mature fruit 117
Figure B.5. Monthly percentage ofnon-fleshy-fruited native species with mature fruit 118
Figure B.6. Monthly percentage ofnon-fleshy-fruited alien species with mature fruit 119
IX Figure B.7. Mean (± 1 SE) monthly percentage ofstems with immature and mature fruits by native tree species .120
Figure B.8. Mean (± 1 SE) monthly percentage ofstems with immature and mature fruits by alien tree species .123
Figure B.9. Mean (± 1 SE) monthly percentage ofstems with immature and mature fruits by native shrub and liana species 125
Figure B.lO. Mean (± 1 SE) monthly percentage ofstems with immature and mature fruits by alien shrub and liana species 126
x CHAPTER 1. INTRODUCTION
BACKGROUND
Recruitment ofseedlings in ecosystems is limited by two main factors, seed
availability and microsite availability (Hughes & Fahey 1988; Schupp 1990). Microsite
quality and abundance are altered when natural disturbance regimes change and as
fragmentation and alien species invasions occur (Peterson & Pickett 1990; Houle 1992).
Seed availability is affected by these changes, but is also altered by the loss or change in
pollinators and seed dispersers (Temple 1977; Benitez-Malvido 1998). In order to address
these theoretical and ecological issues regarding seed limitation, seed dispersal and soil
seed bank composition were investigated in a mesic forest fragment in the Hawaiian
Islands. Seed size and implications for conservation management are also addressed.
Invasion ofnative ecosystems by alien species, in particular alien plant species, is an issue ofglobal concern, especially on oceanic islands (Mooney & Drake 1986;
Vitousek 1988; Loope & Mueller-Dombois 1989; Kitayama & Mueller-Dombois 1995;
Vitousek et al. 1995). Invasion ofalien plant species in native ecosystems usually follows a disturbance ofone kind or other (i.e. anthropogenic alteration, stochastic events). As these disturbances continue, the natural disturbance regime will usually change causing alien species to spread and modify native ecosystems (Vitousek 1988;
Kitayama & Mueller-Dombois 1995; Vitousek et al. 1995).
Frequent anthropogenic and stochastic disturbances lead to the creation offorest fragments (Lovejoy et al. 1984; Vitousek et al. 1995; Watson 2002). In general, fragments are defined as remnants ofpreviously more continuous features, isolated by the
1 imposition ofa contrasting matrix (e.g. native vegetation surrounded by
anthropogenically altered habitat) (Harris 1984; Watson 2002). In particular, island (e.g.
oceanic islands) systems are defined as disjunct, isolated patches that were never
contiguous with other patches and have developed their biota exclusively from colonists
(Whittaker 1998; Watson 2002). The key difference between these systems is their
origin: fragments are remnants ofa previously widespread habitat, whereas islands have
always been restricted and isolated in their spatial extent (Watson 2002). Forest
destruction and fragmentation increases the vulnerability ofthe forest tree community to further disturbances (Lovejoy et al. 1984; Matlack 1994a) and lead to environmental changes that drastically influence the conditions ofthe under-story (Kapos 1989).
A general consequence ofdisturbance, especially fragmentation, is the creation ofboundaries or edges between the disturbed and undisturbed areas (Saunders et al.
1991). The dynamics and structure ofadjacent systems are influenced by these boundaries (Gosz 1991; Ryszkowski 1992). Edges bounding forest fragments and disturbed areas may regulate the distribution ofresources and movement oforganisms between them (Crist et al. 1992; Johnson et al. 1992), thus altering the abundance and distribution oforganisms across the landscape (Janzen 1983; Mills 1995; Murcia 1995).
For example, edges may affect seed dispersal and consequently, with time, the location and structure ofedges. Edges bounding large~scale anthropogenic forest clearings may primarily affect plant colonization from distance seed sources, whereas edges bounding small-scale disturbances, such as tree~fall gaps, may primarily affect plant recruitment from the existing soil seed bank (Harper 1977; Matlack 1994b).
2 When tropical forests are fragmented, increased edge effects may lead to
compositional shifts towards earlier successional species and away from species that are
restricted to more mature and less chronically disturbed forests (Laurance & Bierregaard
1997; Tabarelli et al. 1999). Forest regeneration along edges originates from the seed
bank via wind·and vertebrate.dispersed seeds (Wilson & Crome 1989) offast-growing
pioneer species present before edge creation (Sizer 1992). In general, pioneer species
have higher growth rates than climax species and can quickly replace climax species at
the edge (Benitez-Malvido 1998). This results in the growth ofa second vegetation layer
in a strip less than or equal to 20 m around the fragment edge (Benitez-Malvido 1998).
As time elapses, this new layer develops into a dense vegetation cover with thick foliage
(Malcom 1994a). In addition, the proportion ofthe forest affected by the edge increases
as fragments become smaller (Benitez-Malvido 1998).
Many formerly extensive and continuous continental environments have become fragmented; insularity has been imposed on them (Drake et at. 2002). These effects are compiled on already small and insular oceanic islands where fragments within islands result. Polynesian forests are currently very fragmented with less than 10% ofnative forest remaining in some areas (Franklin et al. 1999; Myers et al. 2000; Wiser et al.
2002). This, combined with a loss ofat least 50% ofthe prehistoric frugivore guild in some countries (Steadman 1995; McConkey & Drake 2002; Meehan et al. 2002), has led to widespread concern over the future offorests in the region (Myers et al. 2000).
In the Hawaiian Islands, given the severe human-induced habitat modification and non-native species introduction, only 20% offormerly forested land area is currently occupied by native and non-native forest (Nelson 1967; Ariyoshi 1986). Though many
3 native forest types continue to exist (Wagner et al. 1999), the remaining dry- to- mesic
native forest types are severely fragmented and degraded, with over 90% ofthe original
dry forests destroyed (Mehrhoff 1993; Bruegmann 1996).
Forest fragmentation and degradation in the Hawaiian Islands is, in part,
attributed to biotic and/or abiotic disturbances that facilitate invasion by alien plant
species (Hughes et al. 1991; Smith & Tunison 1992; Kitayama & Mueller-Dombois
1995). In general, the most successful plant invaders into disturbed areas are those
species with seed attributes such as long-distance dispersal and long-lived seed banks
(Swaine & Hall 1983; Young et al. 1987; Thompson 1992). Few native plant species in
the Hawaiian Islands possess these weedy attributes (Loope & Mueller-Dombois 1989).
Another particularly troubling phenomenon that seriously affects the persistence ofnative communities is the almost complete lack ofnatural reproduction ofmany native tree species in some communities (Medeiros et al. 1986; Loope 1998; Cabin et al. 2000). The lack ofnatural reproduction is, in part, anecdotally attributed to alien species invasions and alternations in natural disturbance regimes (Hughes et al. 1991; Medeiros et al.
1993). Alien species invasions and frequent disturbance contribute to the loss ofnative dispersal agents. Without native dispersal agents, it is assumed seed shadows and seed bank composition ofnative species prior to the extinction ofnative dispersal agents are modified (Loope & Mueller-Dombois 1989; Hughes et al. 1991; Smith & Tunison 1992;
Medeiros et al. 1993; Kitayama & Mueller-Dombois 1995). The future structure ofnative forests and forest remnants could be dramatically influenced and altered.
4 Seed Dispersal
Seed dispersal plays a significant role in population dynamics ofcontinuous and
fragmented forests. The life cycle ofseed plants consists oftwo ecologically distinct
phases, a sessile phase and a dispersal phase (Ericksson & Ehrlen 1992). The second of
these two phases is defined as the dissemination offruits, diaspores or individual seeds
via abiotic or biotic vectors (Wilson & Traveset 2000). Abiotic vectors include wind and
gravity, while biotic vectors include a wide range ofdiversity in vertebrate and
invertebrate species (Wilson & Traveset 2000).
Many factors can affect seed dispersal in forested areas. Distance from seed
source and effectiveness ofdispersers are two factors (McClanahan 1986; Ferguson &
Drake 1999). In the neotropics, the importance ofbird dispersal in regeneration ofnative
plants tends to decrease with decreasing rainfall, while wind dispersal increases (Howe&
Smallwood 1982). This relationship may hold true for Hawaii as well (Garrison 2005).
Recent research in dry and mesic forests in Hawaii suggests the seeds ofmany native over-story plant species are dispersed by wind (Garrison 2005) or the dispersal vector is extinct. Despite this general pattern, many ofthe under-story plants and smaller trees appear to be adapted for dispersal by birds (Stone 1985).
The role Hawaii's native bird species play in seed dispersal ofnative plant species is relatively unknown, since approximately halfofthese bird species were extinct before
European scientists could observe them (Olson & James 1982; James 1995; Steadman
1995). The Hawaiian avian biota is composed oftwo distinct groups: passerine and non passerine. The passerine group, some ofwhich are locally known as honeycreepers, are predominately nectarivorous and/or insectivorous (James & Olson 1991), and do not
5 contribute to seed dispersal. The non-passerine group is quite diverse (including geese,
ducks, rails, ibises, and raptors), and some ofthem could possibly have once utilized a
large array offood sources, including fruit and seed (Olson & James 1991), leading to
seed dispersal. Ofthe 39 species ofendemic Hawaiian non-passerine birds, 31 are known only as fossils. Ofthe remaining 8, two are now extinct and six are federally listed
as endangered (Olson & James 1991; Steadman 1995). Currently, many ofthe remaining native birds are restricted in habitat (Scott et al. 1986) and are either on the verge of extinction and/or very rare at low elevations (James & Olson 1991).
In the absence ofnative birds, alien bird species are thought to play an important role in the dispersal ofboth native and alien plant species in Hawaii (Cuddihy & Stone
1990). In general, the replacement ofnative birds by alien ones could result in the loss of potential pollinators and lead to a reduction in the seed rain ofthe original vegetation
(Temple 1977; Benitez-Malvido 1998). Such a result is largely attributed to alien birds having different diet and foraging behavior than native bird species (Chimera 2005). In studies elsewhere, remnant populations ofnative birds remain in closed habitat and rarely venture across forest clearings (Spears 1987; Bierregaard et al. 1992). A reduction in seed rain may also be due to the poor dispersal capabilities ofmany tropical tree species
(Whitmore 1983), because many may be unable to colonize fragments separated by forest clearance (Bierregaard et al. 1992). In some cases, however, remaining mature-forest trees within altered forest or cleared pasture can still become important seed sources for tropical rain forest recovery (Guevara & Laborde 1993), particularly in instances offorest clearings.
6 Seed Bank
A "seed bank" is an aggregation ofungerminated., viable seeds (Baker 1989; Leck
1989) present on or in the soil or associated litter. Soil seed banks have spatial and
temporal dimensions. Spatial dispersion may be both horizontal and vertical, reflecting
initial dispersal onto the soil and subsequent movement, germination, survival and
mortality (Leck 1989).
The composition ofthe soil seed bank is determined by input and loss ofseeds.
Seed bank input is determined by seed rain within a community (Leck 1989). Usually
local dispersal predominates, but inputs from distant seed sources can occur and contribute substantially to the vegetation and community structure (Leck 1989). Loss from the seed bank results from genetically controlled physiological responses to environmental cues such as light, temperature, water, and chemical stimulants that lead to germination (Leck 1989). Loss also results from death due to pathogens, predators and natural senescence (Louda 1982; Leck 1989).
Three general seed bank syndromes exist: transient, persistent and pseudo persistent, though there are variations ofeach syndrome (Harper 1977; Cook 1979, 1980;
Louda & Zed1er 1985; Garwood 1989). Species with seeds are present in the soil only briefly following dispersal are classified as having transient seed banks. Persistent seed banks occur when seeds are always in the soil regardless ofdispersal phenology and are usually characterized by very small, lightweight seeds, especially those ofweedy and ephemeral species (Harper 1977; Cook 1979, 1980; Louda 1982). Pseudo-persistent seed banks occur when seeds are dispersed throughout the year and are thus always in the soil, but the longevity ofindividual seeds is short. The density ofthese species in the soil
7 fluctuates with the density in the seed rain. In the Hawaiian Islands, some alien species tend to fonn persistent seed banks (Drake 1998), which suggests that these aliens will increase in abundance in the vegetation, especially in fragmented vegetation.
Frequent disturbance can eliminate or drastically reduce native seed banks
(Young et at. 1987). Restoration success ofnative vegetation depends on the establishment ofspecies in the under-story (Lugo 1992), which in turn depends on what seeds are present in the seed bank at the time ofthe restoration activity as well as what seeds are brought in by the wind and seed dispersers (Smith 1975; Young et at. 1987;
Robinson & Handel 1993). Therefore, soil seed bank composition and seed dispersal play extremely important roles in the restoration ofplant communities in deforested and fragmented areas (McClanahan & Wolf 1993). Forest management should minimize disturbances, to prevent germination ofcompetitive alien species from buried seeds
(Bossuyt et al. 2002).
Seed Size
There is a diverse range ofshapes and sizes ofseeds among plant species ofthe world. Among species, seeds range from dust-like seeds ofOrchidaceae across tens of orders ofmagnitude to the double coconut Lodoicea seychellarum (Harper et al. 1970).
Within species, variation in seed size is present, but usually less than halfan order of magnitude. Variation in seed size represents a fundamental trade-offbetween producing more small seeds versus fewer large seeds (Leishman et al. 2000). Optimal seed size for a particular species is determined, in part, by evolutionary responses to environmental conditions and selection pressure. In general, small seeds (seed mass < 1.0 mg) are more
8 often dispersed by birds, wind or an unassisted dispersal vector (Hammond & Brown
1995, Leishman et al. 1995). Small seeds are also able to escape predation and tend to
dominate the soil seed bank. Small seeds are usually persistent and are more likely to find
suitable microsites for germination and growth than large seeds (Harper et a11970;
Leishman et al. 2000). In contrast, large seeds (seed mass :2: 1.0 mg) are often dispersed
by mammals, large birds or gravity (Hammond & Brown 1995, Leishman et al. 1995).
Large seeds are more often removed by seed predators and less likely to be incorporated
into a persistent seed bank. Large seeds are usually viable only for a short period, but
seedlings produced from large seeds are able to tolerate drought, herbivory, and shade
better than many seedlings from small seeds (Thompson 1987; Leishman et al. 2000).
Lack ofRecruitment
Two views concerning the role ofrecruitment for forest dynamics are presented.
The first view is that populations are "dispersal limited," with low and uncertain seed supply being the cause for absence or rarity (Fleming & Heithaus 1981; Hughes et al.
1988; Schupp 1990). A second view ascribes a more limited role in the dynamics of forests to seed supply; the focus shifts to distribution and quality ofmicrosites for seedling establishment (Peterson & Pickett 1990; Houle 1992) and factors affecting growth and mortality in seed banks and seedling stages (Burton & Bazzaz 1991; Reader
& Buck 1991). Often, the rate ofrecruitment in plant populations is dependent on both microsite availability and seed availability (Louda 1982; Louda & Zedler 1985; Fowler
1986; Hughes et al. 1988; Klinkhamer & de long 1989; Peart 1989; Crawley 1990;
Ericksson & Ehrlen 1992). Microsite and seed availability are determined by factors
9 such as seed dispersal, seed predation, disturbance frequency, or herbivory (Fowler
1986; Peart 1989; Reader & Buck 1991). In this study, seed dispersal as a factor ofseed
availability was investigated in a mesic Hawaiian forest. Soil seed bank composition was
analyzed to better understand the effects offragmentation on native species recruitment and its potential importance in community restoration.
For the purpose ofthis study, terms and areas require definition. The term native refers to a plant species which is indigenous or endemic to the Hawaiian Islands (Wagner et al. 1999). The term 'alien' refers to plant species not indigenous or endemic to the
Hawaiian Islands. Areas referred to as native are those that are dominated by native plant species; i.e., 70 percent cover or greater ofthe upper canopy ofthe forest is composed of native species. Areas referred to as alien or non-native are those that are dominated by alien plant species; i.e., 70 percent cover or greater ofthe upper canopy ofthe forest is composed ofalien species. The term edge refers to a strip ofboundary layer vegetation of any width, but rarely wider than 20 m (Benitez-Malvido 1998) between native and alien vegetation. This includes any area that is not dominated by either native or non-native vegetation; i.e. neither native nor alien species dominate 70 percent cover ofthe upper canopy ofthe forest. Consult Appendix A for more information on the characterization of the vegetation at the study site, methods, and results.
This study is ofparticular importance in the Hawaiian Islands for many reasons.
First, few studies investigating the ecological relationships ofseed dispersal and soil seed bank composition have been conducted in the Islands. Second, few studies ifany have been conducted investigating seed limitation in native forests. Third, few studies ifany address the importance ofseed dispersal and soil seed bank composition in the processes
10 ofcolonization and/or invasion ofplant species in the Hawaiian Islands. Lastly, the
successful management ofHawaii's unique species and ecosystems rely on knowledge
gained from primary ecological research and its incorporation into conservation practices.
Ecologically based practices may allow land managers to quickly achieve goals; in
particular, to identify which species are ofpriority for control and to identify mechanisms
that alien species use to disperse seeds. Results obtained from seed dispersal and soil seed
bank studies may also provide insight into the long-term viability ofa species (i.e.
effective and/or viable population size) or community and the likelihood ofextinction.
QUESTIONS & HYPOTHESES Seed Dispersal 1. Which native and non-native species, ifany, are having their seed dispersed away from the parent individual? a. A greater density ofseed from alien species than native species are dispersed. 2. Is there seed exchange between native and alien vegetation types? a. Seed ofalien species are more likely to be dispersed into native vegetation than seed of native species into alien vegetation. b. Greater densities ofseed from alien species are dispersed into edge than into native vegetation. 3. Does seed size affect the probability ofdispersal by vertebrates? a. Small seeded species are more likely to be dispersed than large seeded species.
11 Seed Bank 1. What is the composition ofthe soil seed bank in native, alien and edge vegetation types? a. Soil seed banks in native, alien, edge vegetation types differ in composition. b. Alien species dominate the soil seed bank in all vegetation types, in regard to species richness and density. c. The soil seed bank in native vegetation has a greater density ofseed from native species than the soil seed bank ofalien and edge vegetation. 2. What functional seed bank types do the species present form? a. The majority of native species have pseudo-persistent or transient soil seed banks. b. The majority ofalien species have persistent soil seed banks. 3. Is there any relationship between seed size and the density ofseed in soil seed bank composition? a. Species with small seeds have persistent soil seed banks. b. Species with large seeds have transient or pseudo-persistent soil seed banks.
12 :'1 CHAPTER 2: PATTERNS OF SEED DISPERSAL
INTRODUCTION
Seed dispersal plays a significant role in population dynamics ofcontinuous and
fragmented forests. The life cycle ofseed plants consists oftwo ecologically distinct
phases, a sessile phase and a dispersal phase (Ericksson & Ehrlen 1992). The second of
these two phases is defined as the dissemination offruits, diaspores or individual seeds
via abiotic or biotic vectors (Willson & Traveset 2000). Abiotic vectors include wind
and gravity, while biotic vectors include a wide range ofdiversity in vertebrate and
invertebrate species (Willson & Traveset 2000).
Many factors can affect seed dispersal in forested areas. Distance from seed source and effectiveness ofdispersers are two factors (McClanahan 1986; Ferguson &
Drake 1999). The role Hawaii's native bird species play in seed dispersal ofnative plant species is relatively unknown, since approximately halfofthese bird species were extinct before European scientists could observe them (Olson & James 1982; James 1995;
Steadman 1995). Currently, many ofthe remaining native birds are restricted in habitat
(Scott et at. 1986) and are either on the verge ofextinction and/or very rare at low elevations (James & Olson 1991).
In the absence ofnative birds, alien bird species are thought to play an important role in the dispersal ofboth native and alien plant species in Hawai'i (Cuddihy & Stone
1990). In general, the replacement ofnative birds by alien ones could result in the loss of potential pollinators and lead to a reduction in the seed rain ofthe original vegetation
13 (TempleI977; Benitez-Malvido 1998). Such a result is largely attributed to alien birds
having different diet and foraging behavior than native bird species. Also, the abundance
ofnative birds has decreased dramatically reducing their prior range to closed forest
environments (Spears 1987; Bierregaard et al. 1992).
SeedSize
There is a diverse range ofshapes and sizes ofseeds among plant species ofthe
world. Variation in seed size represents a fundamental trade-offbetween producing more
small seeds versus fewer large seeds (Leishman et al. 2000). Optimal seed size for a
particular species is determined, in part, by evolutionary responses to environmental conditions and selection pressure. In general, small seed (seed mass ~ 0.1 mg) rather than large seed (seed mass> 0.1 mg) are most often dispersed by birds, or wind (Hammond &
Brown 1995, Leishman et al. 1995). In contrast, large seed are typically dispersed by mammals, large birds or gravity (Hammond & Brown 1995, Leishman et al. 1995).
Lack ofRecruitment
Two views concerning the role ofrecruitment for forest dynamics are presented.
The first view is that populations are "dispersal limited," with low and uncertain seed supply being the cause for absence or rarity (Fleming & Heithaus 1981; Hughes & Fahey
1988; Schupp 1990). A second view ascribes a more limited role in the dynamics of forests to seed supply. The focus shifts to distribution and quality ofmicrosites for seedling establishment (Peterson & Pickett 1990; Houle 1992) and factors affecting growth and mortality in seed banks and seedling stages (Burton & Bazzaz 1991; Reader
14 &Buck 1991). Often, the rate ofrecruitment in plant populations is dependent on both microsite availability and seed availability (Louda 1982; Louda & Zedler1985; Fowler
1986; Hughes et aZ. 1988; Klinkhamer & de long 1989; Peart 1989; Crawley 1990;
Ericksson & Ehrlen 1992). Microsite and seed availability are determined by factors such as seed dispersal, seed predation, disturbance frequency, or herbivory (Fowler
1986; Peart 1989; Reader & Buck 1991).
This study is ofparticular importance in the Hawaiian Islands for many reasons.
One, few studies investigate the ecology ofseed dispersal in island communities. Two, few studies ifany have been conducted investigating seed limitation in native forests.
Lastly, the successful management ofHawaii's unique species and ecosystems rely on knowledge gained from primary ecological research and its incorporation into conservation practices. Here, seed dispersal was investigated as a factor limiting seed availability. I investigated which native and alien species, ifany, were having their seed dispersed away from the parent individual. If, there was seed exchange between native and alien vegetation types. Lastly, ifseed size affected the probability ofdispersal by vertebrates.
15 METHODS
Study Site
This study was conducted along the Kalua'a drainage within The Nature
Conservancy ofHawaii's (TNCH) Honouliuli Preserve, O'ahu, Hawai'i (Figure 2.1). The
1,494-hectare preserve is situated between 366-945 m (1,200 and 3,100 feet) elevation on the eastern slope ofthe Wai'anae Mountain Range. The range ofmoisture conditions along a continuum ofrelatively dry habitats place the Wai'anae Mountains among the most biologically diverse in the entire Hawaiian archipelago (Wagner et al. 1999).
Honouliuli is home to 70 native rare and endangered plant and animal species and six native communities. However, the native communities are fragmented and occupy small and large pockets ofthe preserve.
16 Legend
Trails Kaluaa fence 1__1 Study site
D,...... ,....:III:~.. 1i a, I\iIll.ilil.tI:I&c
Figure 2.1. Study area within Kalua'a drainage, Honouliuli Preserve, The Nature Conservancy Hawaii. (UTM coordinates 593322.76E, 2373405N)
17 Large-scale modification to the lands ofHonouliuli began between 1815 and
1830, during the sandalwood trade (Cuddihy & Stone 1990; Kirch 1982). This disturbance was accompanied by the introduction oflivestock, such as cattle and goats, which had free range and devastated much ofthe native vegetation (Honouliuli Preserve
Master Plan 2001). In 1877, when James Campbell purchased the land that now includes
Honouliuli Preserve, he reportedly drove 32,347 wild cattle offthe land. The wild cattle were then replaced with higher quality short-homed cattle for Campbell's beefranch.
Prior to heavy human use, the native forests ofHonouliuli are believed to have functioned as a healthy watershed (Honouliuli Preserve Master Plan 2001). However, by the early 1900s, most ofHonouliuli's forests had been destroyed after decades of trampling hooves, sandalwood harvesting, and agriculture. Major reforestation efforts in
Honouliuli occurred in the late 1920s to early 1940s. Nearly 1.5 million trees (mostly fast-growing non-natives) were planted along the mid-elevation slopes ofHonouliuli by
Civilian Conservation Corps within a seven-year period (1934-41). This was the largest concentration oftree planting on O'ahu. The main threats affecting Honouliuli Preserve are habitat loss and fragmentation, change in composition/structure ofhabitat, and change in fire patterns (Honouliuli Preserve Master Plan 2001).
The Kalua'a drainage comprises the northern most portion ofthe Honouliuli preserve and is classified as low elevation dry to mesic forest habitat (Wagner et al.
1999). The annual rainfall is approximately 1,000 mm (40 inches) (Honouliuli Preserve
Master Plan 2001). At the end of2002, rnCH completed a 43.7-hectare fence protecting a portion ofdry-mesic forest, specifically classified as Oahu diverse mesic forest, within
Kalua'a drainage between 600-800 m in elevation (1800-2400 ft). The study site is
18 located within this area is at UTM coordinates 593322.76E, 2373405N. The site includes
a 2.0-hectare native forest fragment and the adjacent alien matrix vegetation to the east
(down slope, toward the mouth ofthe valley). The native forest fragment is surround by alien dominated vegetation.
TNCH personnel conduct restoration activities and control for rodents
(rodenticide in bait stations) within the native forest fragment. Restoration ofrare and endangered plant species and rodent control began in January 2002. Potentially large populations ofRattus exulans and/or R. rattus exist throughout the drainage, although only six bait stations containing rodenticide are located in the native forest fragment.
Description o/Vegetation
The study site supports closed-canopied forest divided into three distinct vegetation types; native, alien and edge. Native vegetation consists mainly ofnative species dominated by endemic trees; Pouteria sandwicensis, Acacia koa, Antidesma platyphyllum and Metrosideros polymorpha (see Appendix A, Table A.2, Figure A.I for more details). Few alien trees and shrubs are present in the native vegetation. This forest is bounded by edge vegetation, surrounded by alien dominated vegetation. Alien vegetation is composed ofa fairly dense understory and a closed canopy, consisting mainly ofalien species and dominated by alien tree species Aleurites moluccana, Psidium cattleianum, P. guajava, and Schinus terebinthifolius (see Appendix A, Table A.2,
Figure A.2 for more details). Edge vegetation forms a narrow strip between native and alien vegetation. The canopy vegetation is neither dominated by native or alien species.
19 Aleurites moluccana is the most common tree species followed by Pisonia brunoniana
(see Appendix A, Table A.2, Figure A.3 for more details).
20 Measurement ofSeed Rain Under Native Canopy, Edge andAlien Canopy
In order to quantify the difference in seed rain among native, edge and alien forest vegetation, seed traps were placed under the canopy in each vegetation type. Seed vouchers were collected from five fruiting individuals ofeach species, either native or non-native, occurring within the study area. Reproductively mature individuals were flagged with colored flagging tape and revisited monthly until the appropriate number of vouchers were obtained. The phenology ofreproductive individuals was recorded monthly for a 12-month period (Appendix B).
A 200-m baseline transect was established within the middle ofthe edge forest community. Eight, parallel, sampling transects were established perpendicular to the baseline transect, running from the baseline transect 100 m in both directions into the native fragment and alien vegetation. Distances between sampling transects were randomly chosen to be at least 8 m but no more than 13 m apart (Figure 2.2). Along sampling transects, one seed trap was placed every 5 m within the edge vegetation (n = 5) and every 10 m in native (n = 9) and alien forest (n = 9) on each segment oftransect (n =
184 total traps). The entire study site encompassed an area ofapproximately 1.6 hectares.
21 Baseline transect 200 1ft
max. distance Iapart 13 m Imin. distance apart 8 m
I•••• •••••••••••1/ I II I Non-native 100 1ft Native :fragment 100 1ft Edge -201ft
Figure 2.2 Diagram oftransect design. Red circles represent seed traps in native and alien communities, spaced 10m from each other. Blue circles represent seed traps on the edge spaced 5 m from each other. Note: parallel sampling transects are randomly placed along the baseline transect, greater than 8 m but less than 13 m from each other. Eight sampling transects were established though only four are shown here.
Seed traps were constructed ofplastic pots (diam 25.5 cm; depth ~19.0 cm) with the bottoms removed and replaced with a cotton cloth secured by rubber bands (Drake
1998). The weave on the cloth was fine enough to retain all seeds, yet allow water to drain. Wire screens were placed over the top ofthe pots and apertures were large enough
(4 x 3 x 2.5 cm hexagons) to allow seeds to fall through, but small enough to discourage rodents from entering and consuming seeds (Drake 1998). The wire screen was depressed
5 cm into the depth ofthe pot in order to prevent seeds from bouncing out. Traps were
2 held in place by stakes. The total area sampled by 184 traps was 9.4 m •
22 The cloth ofeach seed trap was collected and replaced every month for a twelve- month period, from June 2003 to May 2004. All material collected from each trap was examined under a dissecting microscope and identified by comparison with voucher specimens. All seeds were counted by species and classified as undamaged ifthey appeared whole and contained embryos, or as damaged ifembryos were absent. Seeds of
Metrosideros polymorpha were classified as undamaged by assuming 10% seed viablity
(Drake 1992). The number ofintact fruits was also recorded. Fruits ofmany species contained multiple seeds; therefore 15 fruits ofeach species were dissected and the seeds inside counted (Table 2.1). The mean number ofseeds per fruit for each species was multiplied by the number offruits from that species found in traps.
Table 2.1 Mean number ofseeds (± SE) contained in 15 fruits for each species.
Species Name Status Seeds per fruit
Acacia koa Native 9.3 (2.8) Antidesma platyphyllum Native 1.1 (0.4) Alyxia oliviformis Native 1.1 (0.3) Bobea elatior Native 10.1 (1.9) Caesalpinia major Alien 1.1 (0.3) Clidemia hirta Alien 408 (11.6) Metrosideros polymorpha Native 211 (11.2) Passiflora edulis Alien 26.7 (3.9) Passiflora suberosa Alien 10.5 (0.4) Pisonia brunoniana Native 1.1 (0.1) Pouteria sandwicensis Native 6.5 (0.8) Psidium cattleianum Alien 10.1 (0.3) Psidium guajava Alien 26.3 (3.9) Psychotria mariniana Native 2.5 (0.5) Psydrax odoratum Native 1.9 (0.4) Schinus terebinthifolius Alien 1.0 (0.0) Toona ciliata Alien 30.6 (7.5)
23 Seed Dispersal Analysis
All seed collected in traps were used to quantify the differences in seed rain among native, alien and edge vegetation types. Seed collected in the seed traps were quantified as "potentially dispersed" ifseed were from species other than those bearing fruits and having crowns within a 2-3 m ofthat particular trap and, for fleshy-fruited species, ifall flesh or pulp was removed from the fruit. Similarly, seed collected in traps neighboring conspecific male plants ofdioecious species were quantified as "potentially dispersed". Seed from intact fruit that matched conspecific species growing within 5 m of the trap were considered "not dispersed."
All seed collected in traps were also categorized by one offour general dispersal vectors: bird-dispersed; gravity-dispersed; wind-dispersed; adhesion-dispersed. Fleshy fruited seed collected in traps were quantified as "bird-dispersed" ifthey were from species other than that ofthe overhanging vegetation. Seed from intact fruits that had likely fallen directly from the parent tree into seed traps were categorized as "gravity dispersed." Also, seed with no obvious dispersal adaptation or that were obviously too large for any birds to handle and were captured at least 10 m away from conspecific species were categorized as "gravity-dispersed." Smaller, wind-borne seed and those with adaptations for dispersal by wind currents (e.g. tufts ofhairs, wings etc.) were classified as "wind-dispersed." Seed having these 'wind-adapted' characteristics, but captured beneath a conspecific tree were counted as "uncertain." Also, seed offleshy-fruited species lacking pulp but captured beneath conspecific species were counted as
"uncertain." This category accounts for the possibilities that birds may have dropped seed from the parent species or that invertebrates consumed pulp from fruits after they fell
24 from parent species. All seed categorized by a dispersal vector were included in the
'dispersed category' except for "gravity-dispersed' seed captured directly beneath
conspecific species. All seed with an "uncertain" dispersal vector and those "gravity
dispersed" seed that fell directly beneath conspecific species were included in the "not dispersed" category.
2 Total seed rain numbers were converted into seed densities (seeds/m ). Total densities ofdispersed seed from native and alien species were compared with paired t tests. Differences in the mean density ofseed dispersed from native and alien species among vegetation types were assessed using a Kruskal-Wallis test. A Chi-squared test identified differences in the proportion ofdispersed seed from native or alien species in each vegetation type.
The presence ofseedlings less than 10 cm tall from all species in the study area was noted in native, edge and alien vegetation types. Thirty points were randomly selected in each forest habitat. Seedlings were counted at each point within 5 m radius of the selected point. Seedling presence may be used as an indirect and biased estimate of seed dispersal.
Seed Size Measurements
Seed mass (mg), greatest length (rom) and greatest width (rom) were measured in order to determine the range ofsizes of"potentially dispersed" and "not dispersed" seed collected in seed traps (see Seed Dispersal Analysis section). For the purpose ofthis study, a 'seed' refers the unit ofdispersal, typically the diaspore, including the embryo, endosperm, and seed coat. Measurements were taken from 15 randomly selected seed
25 from each species. The majority ofseed were collected from seed traps or seed vouchers.
All seed collected in traps were also categorized as either small or large. For the purpose ofthis study, a small seed has seed·mass less than 1.0 mg, greatest length less than 3 mm, and greatest width less than 2.5 mm. whereas a large seed has a mass, length and width gathan than or equal to these values.
The proportion ofdispersed seed captured was calculated for large and small seed by dividing the density ofdispersed seed by the density oftotal seed rain. A Chi-squared test was used to test for significant divergence in the proportions ofdispersed seed from the expected proportions, ifany, among vegetation types. Spearman's rank correlation was used to test for relationships between seed mass, length, width, and total numbers of all "potentially dispersed" seeds collected in all seed traps. Spearman's rank correlation was also used to test for relationships between seed mass, length, width, and total numbers ofbird-dispersed seed collected in all seed traps.
Characterization ofVegetation
Vegetation cover in the study site was sampled at 320 points using the point intercept method (Bonham 1989). For a more detailed description ofmethods used, and results, consult Appendix A.
26 RESULTS Seed Rain
A total of429,595 seed from 24 ofplant species were found in 184 seed traps in native, edge and alien vegetation types at Kalua'a (Table 2.2). Ofthese, 420,432 (97.9%) were alien species and 9,163 (2.3%) were native species (Table 2.2). The seed rain was dominated by a single alien species, Clidemia hirta, with over 90% ofthe mean seed density (Table 2.2). Excluding Clidemia hirta, seed density ofalien species was three times as abundant as seed ofnative species (Table 2.2, Figure 2.3).
Greater densities ofseed from alien species than native species were found in the seed rain in all vegetation types (Table 2.2, Figure 2.3). Excluding Clidemia hirta from the seed rain, there was a greater density and relative frequency ofnative seed than alien seed in the native and edge vegetation (Table 2.2, Figure 2.3). Tests ofsignificance between species were not applicable due to the abnormality ofthe data, even after data were transformed.
27 Table 2.2. Abundance and relative mean density oftotal seed rain (Abs. = absolute, % = relative mean density) and mean 2 density (seeds/m ) (Mean = mean seed density, ReI. % = relative mean density) in native, edge and alien vegetation types for all species collected in 184 seed traps in Kalua'a drainage from June 2003 to May 2004. Total Seed Rain Native Edge Alien Abs. % Mean ReI. % Mean ReI. % Mean ReI. % Native species Trees Acacia koa 3464.0 0.81 43.50 0.78 20.22 0.46 23.80 0.73 Antidesmaplatyphyllum 149.0 0.03 3.02 0.05 0.73 0.02 0.05 1.5 x 10-3 Bobea elatior 252.0 0.06 2.53 0.05 3.93 0.09 1.65 0.05 Metrosideros polymorpha 4817.0 1.12 599.00 10.8 792.00 17.86 59.90 1.85 Pisonia brunoniana 88.0 0.02 0.85 0.02 0.49 0.01 0.86 0.03 Pouteria sandwicensis 110.0 0.03 0.51 0.01 2.81 0.06 0.59 0.02 Psychotria mariniana 151.0 0.04 7.30 0.13 0.12 2.7 x 10-3 0.54 0.02 tv 3 3 00 Psydrax odoratum 75.0 0.02 0.22 3.9 x 10- 0.16 3.6 x 10- 1.38 0.04 Shrubs Bidens torta 37.0 8.6 x 10-3 0.77 0.01 0.05 1.1 x 10-3 0.04 1.2 x 10-3 Lianas Alyxia oliviformis 20.0 4.7 x 10-3 0.21 3.7 x 10-3 0.29 6.5 x 10-3 0.04 1.2 x 10-3 Total native species 9163.0 2.13 657.9 11.86 820.8 18.51 88.5 2.73
Alien species Trees Aleurites moluccana 10.0 2.3 x 10-3 0.00 0.00 0.08 1.8 x 10-3 0.00 0.00 Grevillea robusta 5.0 1.1 x 10-3 0.00 0.00 0.00 0.00 0.02 6.1 x 10-4 Psidium cattleianum 513.0 0.12 2.86 0.05 6.00 0.14 5.95 0.18 Psidium guajava 332.0 0.06 6.19 0.11 0.40 9.0 x 10-3 1.11 0.03 Schinus terebinthifolius 805.0 0.19 6.50 0.12 4.28 0.09 9.40 0.29 Spathodea campanulata 49.0 0.01 0.14 2.5 x 10-3 0.16 3.6 x 10-3 0.88 0.03 Toona ciliata 17066 3.97 7.12 0.13 77.00 1.74 377.10 11.64 Table 2.2. Continued. Abundance and relative mean density oftotal seed rain (Abs. = absolute, 2 % = relative mean density) and mean density (seeds/m ) (Mean = mean seed density, ReI. % = relative mean density) in native, edge and alien vegetation types for all species collected in 184 seed traps in Ka1ua'a drainage from June 2003 to May 2004. . Total Seed Rain Native Edge Alien Abs. % Mean ReI. % Mean ReI. % Mean ReI. % Shrubs Clidemia hirta 388738 90.49 4686.00 84.49 3470.00 78.25 2670.00 82.40 Rubus rosifolius 911.0 0.21 9.77 0.18 8.29 0.19 9.84 0.30 Lianas Caesalpinia major 8.0 1.8 x 10-3 0.00 0.00 0.00 0.00 0.09 2.7 x 10-3 Passiflora edulis 341.0 0.08 7.30 0.13 0.12 2.7 x 10-3 0.36 0.01 Passiflora suberosa 11626 2.70 162.60 2.93 46.28 1.04 75.60 2.33 Graminoids Oplismenus hirtellus 28.0 6.5 x 10-3 0.00 0.00 0.00 0.00 1.24 0.04 N \0 Total alien species - Clidemia hirta 31694.0 7.4 202.5 3.65 142.6 3.22 481.6 14.86 + Clidemia hirta 420432.0 97.9 4888.5 88.14 3612.6 81.49 3151.6 97.27 All species - Clidemia hirta 40857.0 9.5 860.4 15.51 963.4 ·21.73 570.1 17.59 + Clidemia hirta 429595.0 100.0 5546.4 100.0 4433.4 100.0 3240.1 100.0 100% l 80% .5 I! "C 60% CD o Native species CD I/) 40% o ~ Alien species '#. (+Clidemia) 20% • Alien species 0% (-Clidemia) Native Edge Alien Total
Vegetation Type ~
Figure 2.3. Percentage ofseed rain for native and alien species in the different vegetation types in Kalua'a drainage from June 2003 to May 2004.
Approximately a third (34%) ofthe total seed rain was comprised ofseed categorized as dispersed (Table 2.3). The remaining 66% ofseeds in the seed rain were categorized as not-dispersed since they were collected from traps under conspecific plant species (see Seed Dispersal Analysis).
30 A total of166,892 captured seed from 20 species were categorized as dispersed in the three vegetation types in Kalua'a (Table 2.3). Ofthe 20 species, 11 were alien and 9 were native. Clidemia hirta (86.9% ofthe relative seed density) was the most common alien species dispersed into all vegetation types (Table 2.3). Metrosideros polymorpha
(5.8%) was the most common native species dispersed into all vegetation types (Table
2.3). A significantly greater density ofseed from alien species than native species (Paired t-test; P < 0.001) were dispersed into all vegetation types (Table 2.3, Figure 2.4).
Excluding Clidemia hirta from the alien species data, densities ofdispersed seed from alien and native species were not significantly different (Paired t-test; P> 0.05) (Table
2.3, Figure 2.4).
There was a significantly greater (Kruskal-Wallis, H= 18.413, df=2, P< 0.05) density ofseed from native species dispersed into local (native) vegetation than into distant (alien) vegetation (Figure 2.5). There were significantly (Kruskal-Wallis,
H=80.92, df=2, P< 0.05) greater densities ofseed from alien species dispersed into distant (native) vegetation than into edge and local (alien) vegetation (Figure 2.5). There was no significant difference in the density ofseed from alien species dispersed into native than into edge vegetation. In contrast, excluding Clidemia hirta from the alien species data, significantly (Kruskal-Wallis, H=59.92, df=2, P< 0.05) greater densities of seed from alien species were dispersed into local (alien) vegetation than into distant
(native) vegetation (Figure 2.5).
31 2 Results from a Chi-square test (including Clidemia hirta: X = 35.43, df= 2, P <
0.05 and excluding Clidemia hirta: X2= 47.68, df= 2, P < 0.05) provided strong evidence that the distribution ofdispersed seed among native species was different from that among alien species. A greater proportion ofnative seed were dispersed into edge vegetation than into native and alien vegetation (Figure 2.6). A greater proportion ofseed from alien species (including Clidemia hirta) than from native species were dispersed away from the major seed source (Figure 2.6). In contrast, the data when excluding
Clidemia hirta showed that a greater proportion ofseed from alien species were dispersed within local vegetation than from native species (Figure 2.6).
Seed of 14 canopy tree species were dispersed into seed traps in all three vegetation types at the study site in Kalua'a drainage. Ofthese, 8 species were native and
6 were alien. A greater proportion ofseed from native than alien tree species were dispersed into the edge and native vegetation (Table 2.3). A greater proportion ofseeds from alien than native tree species were dispersed in the alien vegetation (Table 2.3).
Seed ofMetrosideros polymorpha, a native tree, were the most abundant seed dispersed by a canopy tree species in the study area (Table 2.3).
32 2 Table 2.3. Relative mean density (seeds/m ) of'not-dispersed' (Not-disp.) and 'dispersed' (Disp.) seed in total seed rain in all 2 2 vegetation types and mean density (seeds/m ) and relative mean density (seeds/m ) ofdispersed seed per seed trap (Mean == mean seed density; ReI. % = relative mean density) in native, edge and alien vegetation and percentage oftotal dispersed seed at Kalua'a from June 2003 to May 2004. Not- . Native Edge Alien Species Status D' DISp. ISp. Mean ReI. % Mean ReI. % Mean ReI. % Total % Canopy tree species Acacia koa Native 73.0 27.0 3.5 ± 1.7 0.2 6.2 ± 3.5 0.4 13.9 ± 3.2 1.1 x 10-2 0.55 Aleurites moluccana Alien 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.00 2 3 Antidesma platyphyllum Native 84.0 16.0 0.5 ± 0.4 2.9 x 10- 0.0 0.0 0.05 ± 0.03 4.0 x 10. 0.01 Bobea elatior Native 0.0 100.0 2.5 ± 1.3 0.2 3.9 ± 1.6 0.2 1.7 ± 1.0 0.1 0.17 3 3 Grevillea robusta Alien 0.0 100.0 0.0 0.0 0.0 0.0 0.02 ± 0.02 2.0 x 10- 5.9 X 10- Metrosideros Native 80.0 20.0 95.5 ± 11.7 6.0 130.3 8.0 4.0 5.78 w 50.8 ± 24.2 w polymorpha ±20.8 2 2 3 Pisonia brunoniana Native 72.0 28.0 0.3 ± 0.1 1.8 x 10. 0.4 ± 0.3 2.2 x 10- 0.05 ± 0.03 4.0 x 10- 0.01 2 3 Pouteria sandwicensis Native 89.0 11.0 0.0 0.0 0.5 ± 0.3 3.3 x 10- 0.0 6.7 X 10- 4.4 X 10-4 Psidium cattleianum Alien 25.0 75.0 2.4 ± 0.7 0.1 3.5 ±1.4 0.2 4.8 ± 1.5 0.4 0.24 2 2 Psidium guajava Alien 7.0 93.0 6.2± 5.9 0.4 0.4 ± 0.2 2.4 x 10- 0.7 ± 0.5 5.5 x 10. 0.18 3 2 Psychotria mariniana Native 88.0 12.0 0.16 ± 0.8 8.0 x 10-3 0.12 ± 7.0 x 10- 0.2 ± 0.08 1.4 x 10- 0.01 0.07 3 2 Psydrax odoratum Native 58.0 42.0 0.13 ± 0.09 7.0 x 10-30.12 ±0.077.0 x 10- 0.5 ±0.2 4.3 x 10- 0.02 Schinus terebinthifolius Alien 68.0 32.0 2.7 ± 0.5 0.2 1.9 ± 0.5 0.1 2.0 ± 0.3 0.2 0.15 2 Spathodea campanulata Alien 0.0 100.0 0.14 ± 0.06 7.6 x 10-2 0.16 ± 0.89.8 x 10- 0.9 ± 0.4 7.4 x 10-2 0.03 Toona ciliata Alien 62.0 38.0 5.9 ± 1.5 0.4 38.2 ± 2.0 119.8 ± 20.2 10.0 3.89 14.0 Native tree species 68.0 32.0 53.0 51.0 26.0 59.3 Alien tree species 37.0 63.0 47.0 49.0 74.0 40.7 2 Table 203. Continued. Relative mean density (seeds/m ) of 'not-dispersed' (Not-disp.) and 'dispersed' (Disp.) seed in total seed 2 rain in all vegetation types and mean density (seeds/rrC) and relative mean density (seeds/m ) ofdispersed seed per seed trap (Mean = mean seed density; ReI. % = relative mean density) in native, edge and alien vegetation and percentage oftotal dispersed seed at Kalua'a from June 2003 to May 2004. Not- . Native Edge Alien Species Status D. DISp. ISp. Mean ReI. % Mean ReI. % Mean ReI. % Total % Shrub or liana species 3 3 2 Alyxia oliviformis Native 32.0 68.0 0.05 ± 0.03 3.0 x 10- 0.04± 2.0 X 10- OJ ± 0.2 2.4 x 10- 0.01 0.04 3 Eidens torta Native 84.0 16.0 0.07 ± 0.05 4.0 x 10- 0.04± 2.0 x 10-3 0.05 ± 0.03 4.0 x 10-3 3.6 x 10-3 0.04 Clidemia hirta Alien 61.0 39.0 1564.0 91.0 1412.0 87.0 942.0 80.0 86.96 w ± 381.0 ± 670.0 ± 177.0 -I::>- Caesalpinia major Alien 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.00 2 Oplismenus hirtellus Alien 51.0 49.0 0.0 0.0 0.0 0.0 0.6 ± 0.3 5.2 x 10- 0.01 3 2 Passiflora edulis Alien 0.0.0 100.0 703 ± 6.0 0.4 0.12±0.7 7.0x 10- 0.4 ± OJ 3.0 x 10- 0.20 Passiflora suberosa Alien 81.0 19.0 10.2 ± 1.8 0.6 10.3 ± 2.3 0.6 34.5 ± 4.9 3.0 1.33 Rubus rosifolius Alien 28.0 72.0 7.6 ± 1.2 0.4 8.12 ± 2.7 0.5 2.8 ±0.08 0.2 0.39
Total native species 79.0 21.0 102.8 ± 6.0 141.6±21. 9.0 67.4 ± 24.4 6.0 6.6 11.9 5 Total alien species 62.0 38.0 1607.0 94.0 1476.0 91.0 1109.0 94.0 93.4 (+Clidemia) ±381.0 ± 670.0 ±179.0 Total alien species 44.0 56.0 42.5 ± 8.93 3.0 63.5 ± 4.0 166.6 ± 20.8 14.0 6.5 (-Clidemia) 14.4 Total 64.0 36.0 1709.0 100.0 1617.0 100.0 1176.0 100.0 100.0 ±380.0 ± 670.0 ±181.0 100%
"0 (I) 80% (I) U) o Native "0 species (I) 60% U) lo- tiil Alien species (I) Q. (+Clidemia) U) 40% ;; .... • Alien species o (-Clidemia) '#. 20%
Native Edge Alien Total Vegetation Type
Figure 2.4. Relative percentage of dispersed seed for native and alien species in the different vegetation types in Kalua'a drainage from June 2003 to May 2004.
2500 - o Native sp
2000 .Aliensp >. (-CH) 'iii- ~Aliensp t: 1500 (I) (+CH) 'C euC Q) 1000 :E 500 l 0 local edge distant Vegetation Type
2 J Figure 2.5. Mean density (seeds/m ) ofseeds dispersed per seed trap from native and alien species in three vegetation types at Kalua'a. +CH:::: including Clidemia hirta, -CH= excluding Clidemia hirta.
35 "C (I) 0.8 native sp. (I) o tn "C ~alien sp. (I) 0.6 I f (+ CH) (I) c. • alien sp. .!Q 0.4 (-CH) "C I c 0 :e 0.2 0 ec. Q. 0 local edge distant Vegetation Type
Figure 2.6. Proportion ofdispersed seed (seed density per vegetation type/seed density from all vegetation types) from native, alien species (+CH) and alien species (-CH) in Kalua'a drainage from June 2003 to May 2004. +CH= including Clidemia hirta, -CH= excluding Clidemia hirta. 'Local' refers to the vegetation type ofthe major seed source (e.g. local = native vegetation for native species; local = alien vegetation for alien species). 'Distant' refers to the vegetation type the greatest distance from the major seed source (e.g. distant = native vegetation for alien species; distant = alien vegetation for native species). Chi-square tests (including Clidemia hirta: X2= 35.43, df= 2, P < 0.05 2 and excluding Clidemia hirta: X = 47.68, df= 2, P < 0.05) provided strong evidence that the distribution ofdispersed seed among native species was different from that among alien species.
Ofthe twenty dispersed species, 0.6 % ofseeds were gravity-dispersed, 89.7 % of seeds were bird-dispersed, 9.7% ofseeds were wind-dispersed and 0.01% ofseeds were by adhesion (Table 2.4). Ofnative species, 30% were gravity dispersed, 50% bird- dispersed, 10% wind-dispersed and 10% by adhesion. Ofalien species, 63% were bird- dispersed, 37% wind-dispersed, and none were dispersed by gravity or adhesion.
Among canopy tree species, seed with wind-dispersal adaptations were more abundant, in seed density, in seed traps than were seed adapted for dispersal by other vectors (Table 2.4). Ofthe eight native tree species captured in the dispersed seed rain,S
(63%) ofthe species had adaptations for bird dispersal, 1 (13%) for wind dispersal, and 2
36 (26%) had no apparent adaptation. Ofthe six alien tree species collected from seed traps,
50% ofthe species had adaptations for bird dispersal and 50% for wind dispersal.
Table 2.4. Mean density (seeds/m2 ± SE) ofdispersed seed from canopy tree species and all species by dispersal vector collected in all seed traps in Kalua'a from June 2003 to May 2004. Category Gravity Bird Wind Adhesion Canopy tree species Native species 8.1 (1.6) 3.3 (0.8) 85.6 (11.5) 0.2(0.1) Alien species 0.0 (0.0) 8.6 (2.5) 58.2 (8.6) 0.0 (0.0) Total % 5.1 7.2 87.6 0.1
All species Native species 8.2 (1.0) 3.3 (0.8) 85.6 (11.5) 0.2 (0.1) Alien species 0.0 (0.0) 1325.0 (220.0) 58.4 (8.6) 0.0 (0.0) Total % 0.6 89.7 9.7 0.01
37 Ofthe 23 species represented in the total seed rain at Kalua'a, 21 were present as seedlings (Table 2.5). Seedlings ofBobea elatior and Metrosideros polymorpha were not found in the study area. A greater frequency ofseedlings from alien species were present than native species (Table 2.5). Seedlings ofsixteen species were found in the native vegetation, six (60% ofseedlings) were native species and 10 (40% ofseedlings) were alien. Seedlings ofAcacia koa were the most widespread, occurring in 73% ofthe native vegetation plot (Table 2.5). Seedlings ofsixteen species were found in the edge vegetation, six ofwhich (34% ofseedlings) were native species and 10 ofwhich (66% of seedlings) were alien. Aleurites moluccana and Pisonia brunoniana seedlings were the most widespread, occurring in 53% ofthe edge vegetation (Table 2.5). Seedlings of 15 species, 3 (9% of seedlings) native and 12 (91 % ofseedlings) alien, were present in the alien vegetation. Toona ciliata seedlings were the most widespread, occurring in 70% of the alien vegetation plots (Table 2.5). The seedlings ofAntidesmaplatyphyllum, Bidens torta, Caesalpinia major, Pisonia brunoniana, Pouteria sandwicensis, Psydrax odoratum, Psychotria mariniana, and Schinus terebinthifolius were only present under conspecific adults in all vegetation types.
38 Table 2.5. Relative frequency ofseedlings ofall species found in the seed rain in native, edge and alien vegetation types in Kalua'a drainage. Native species are marked with an asterisk (*). (n = 30 for each forest type; n = 90 for all forest types). Alien Seedling Species Native Forest Edge All forest types Forest Acacia koa* 73.3 33.3 6.7 37.8 Clidemia hirta 40.0 43.3 30.0 37.8 Aleurites moluccana 30.0 53.3 20.0 34.4 Toona ciliata 6.7 23.3 70.0 33.3 Pisonia brunoniana* 20.0 53.3 16.7 30.0 Psidium cattleianum 13.3 23.3 43.3 26.7 Pouteria sandwicensis* 46.7 23.3 0.0 23.3 Passijlora suberosa 20.0 13.3 30.0 21.1 Spathodea campanulata 3.3 23.3 33.3 20.0 Psidium guajava 6.7 23.3 26.7 18.9 Oplismenus hirtellus 0.0 13.3 40.0 17.8 Schinus terebinthifolius 3.3 23.3 13.3 13.3 Rubus rosifolius 0.0 6.7 26.7 11.1 Alyxia oliviformis* 20.0 10.0 0.0 10.0 Antidesma platyphyllum* 20.0 3.3 0.0 7.8 Grevillea robusta 0.0 0.0 13.3 4.4 Psydrax odoratum* 0.0 0.0 13.3 4.4 Bidens torta* 10.0 0.0 0.0 3.3 Caesalpinia major 0.0 0.0 10.0 3.3 Psychotria mariniana* 6.7 3.3 0.0 3.3 Passijlora edulis 6.7 0.0 0.0 2.2 Bobea elatior* 0.0 0.0 0.0 0.0 Metrosideros polymorpha* 0.0 0.0 0.0 0.0
39 Seed Size andDispersal
Ofthe 429,595 seed collected, 397,014 (92.4%) seed were from small-seeded species and 32,581 (7.6%) seed were from large-seeded species. These results were driven by a single species Clidemia hirta (Table 2.6). A Chi-squared test provided strong evidence that the proportion ofdispersed and not-dispersed seed ofsmall and large size
2 were similar (including Clidemia hirta: X = 1.85, df= 1, P > 0.05; excluding Clidemia
2 hirta: X = 3.811, df= 1, P > 0.05). Ofthe 21 dispersed species collected in the seed rain
(Table 2.7), there was a significant negative relationship among numbers ofdispersed seed and seed mass (rs = -0.581, P = 0.004), seed length (rs = -0.648, P = 0.001), and seed width (rs = -0.671, P < 0.001) (Figures 2.8-2.9).
40 Table 2.6. Relative mean density of 'not-dispersed' (Not-disp.) and 'dispersed' (Disp.) small and large seed in all vegetation types and mean density (seeds/m2 ± 1 SE) of dispersed seed per seed trap and percentage oftotal dispersed seed from 184 seed traps in native, edge and alien vegetation at Kalua'a from June 2003 to May 2004.
Not- . Category Native Edge Alien Total dispersed d'ISp. DISp. Mean % disp. Small seed 64.0 36.0 1667.0 (380.0) 1551.0 (669.0) 996.0 (178.0) 3796.0 (374.0) 92.4 (+Clidemia) Small seed 79.8 21.2 103.2 (11.8) 138.4 (20.8) 54.2 (24.2) 91.6 (11.5) 2.2 (-Clidemia) Large seed 67.0 33.0 42.1 (9.1) 66.8 (14.7) 179.8 (21.1) 311.5(21.3) 7.6
100% .. + .. w/Clidemia >. •. ~ c 80% w/out Q) • :s Clidemia :c::r 60% .::Q) Q) > 40% .-~ -...Q) 20% 0%
..- Figure 2.7. Seed size distributions for dispersed seed in Kalua'a drainage from June 2003 to May 2004 by seed size.
41 Table 2.7. Mean (± 1 SE) seed (diaspore) mass (mg), seed length (mm) and width (mm) ofall species collected in the seed rain at Kalua'a drainage from June 2003 to May 2004. Size category (Small seed = seed mass < 1.0 mg, length < 3 mm, and width < 2.5 mm; Large seed = mass ~ 1.0 mg, length ~ 3 mm, and width ~ 2.5 mm). Sample sizes for each species are the same (n=15). Native species are identified by an asterisk (*). Seed Category Dispersal Dry mass ofseed Greatest Greatest Size vector w/o pulp length w/o width w/o Category (mg) pulp (mm) pulp (mm) Acacia koa* Gravity 70.9 (9.01) 9.49 (0.08) 5.25 (0.7) Large Aleurites moluccana Gravity 11300.0 (7.9) 14.6 (0.09) 9.5 (0.09) Large Alyxia oliviformis* Bird 529.1 (11.56) 8.5 (0.09) 6.6 (0.11) Large Antidesma platyphyllum* Bird 84.1 (3.56) 8.6 (1.2) 6.8 (0.98) Large Bidens torta* Gravity 1.6 (0.71) 13.2 (2.1) 1.0 (0.2) Large Bobea elatior* Bird 12.6 (0.89) 6.3 (0.11) 3.5 (0.09) Large Caesalpinia major Gravity 1584.1 (4.56) 18.0 (2.5) 14.5 (3.1) Large Clidemia hirta Bird 0.006 (0.001) 0.7 (0.03) 0.5 (0.05) Small Grevillea robusta Wind 6.3 (1.3) 15.1 (1.1) 8.3 (0.19) Large Metrosideros polymorpha* Wind 0.012 (0.003) 2.25 (0.21) 0.3 (0.01) Small Oplismenus hirtellus Gravity 0.1 (0.02) 0.89 (0.04) 0.5 (0.01) Small Passiflora edulis Bird 23.4 (1.32) 5.6 (0.10) 3.7 (0.11) Large Passiflora suberosa Bird 5.2 (1.21) 4.4 (0.10) 2.7 (0.11) Large Pisonia brunoniana* Adhesion 376.7 (8.91) 75.1 (5.93) 4.4 (1.21) Large Pouteria sandwicensis* Gravity 1159.9 (12.3) 24.5 (1.55) 14.3 (0.92) Large (bird) Psidium cattleianum Bird 92.3 (11.89) 6.5 (0.08) 3.6 (0.09) Large Psidium guajava Bird 335.8 (4.54) 4.3 (0.11) 3.4 (0.10) Large Psychotria mariniana* Bird 97.5 (8.93) 9.5 (0.09) 7.3 (0.11) Large Psydrax odoratum * Bird 55.1 (8.22) 7.4 (0.11) 5.5 (0.08) Large Rubus rosifolius Bird 0.5 (0.02) 1.3 (0.09) 0.85 (0.02) Large Schinus terebinthifolius Bird 11.5 (1.8) 3.4 (0.10) 3.7 (0.12) Large Spathodea campanulata Wind 4.5 (0.91) 14.5 (3.41) 11 (1.22) Large Toona ciliata Wind 4.87 (1.91) 16.25 (3.89) 4.25 (0.79) Large
42 10 ---.r------,
+ ++ a 5 - a C/) +++ + C/) a d- ~ a I o 0 a C> .Q o - + a
0
+ -5 - a L..,,------...------r------J I I -5 0 5 log-seed density
2 Figure 2.8. Seed mass (mg) and mean seed density (seeds/m ) in the dispersed seed rain ofnative (+) and alien (0) species.
8 - 7 -
6- + + 5 - a + a m 4- ++ a Q) + L.. + m 3 - -100 I 00 C> + a 0 2- 1 - o - a + -1 - a a -2 - I I I -5 0 5 log-seed density
2 2 Figure 2.9. Seed area (m ) and mean seed density (seeds/m ) in the dispersed seed rain of native (+) and alien (0) species.
43 Ofthe small seeded species, 93.7% were bird dispersed, 6.2% were wind dispersed, and the remaining 0.1 % was gravity dispersed (Table 2.8). Ofthe large seeded species, 33.7% were bird dispersed, 57.9% were wind dispersed, 8.2% were gravity dispersed and 0.2% was adhesion dispersed (Table 2.8).
In Kalua'a, a range ofseed sizes was found in the dispersed seed rain. The range ofseed sizes was greatest among seeds dispersed by birds (Figure 2.10). The seed from
13 fleshy-fruited plant species were captured in the study area and categorized as dispersed by birds. Ofthese bird-dispersed species, two species were categorized as small~seeded and eleven species as large-seeded (Table 2.7). There were significant negative relationships among numbers ofbird-dispersed seeds and seed mass (rs = -0.775,
P = 0.002), seed length (rs = -0.868, P < 0.001), seed width (rs = -0.923, P < 0.001)
(Figure 2.11-2.13).
44 Table 2.8. Mean density (seeds/m2 ± 1 SE) ofdispersed seed dispersal vector collected in all seed traps in Kalua'a from June 2003 to May 2004. Category Bird Wind Gravity Adhesion Small seed 1294.0 (219.0) 85.2 (11.5) 0.2(0.1) 0.0 (0.0) Large seed 33.9 (5.7) 58.2 (8.6) 8.2 (1.6) 0.2 (0.1) Total % 89.7 9.7 0.5 0.01
I' 100% I I 90% I 80% I I -~ 70% -,---'------, I ! I~bird II ->. (,) 60% r:: Iii ImlWind II CI) 50% ::s i:, Dgravity II C'" 40% CI) a- i. adhesion II u. 30% I. 20% I 10% I I 0% '1Ii Jl
Seed mass (mg)
Figure 2.10. Seed size distributions for bird-, wind-, gravity-, adhesion-dispersed seeds in Kalua'a drainage from June 2003 to May 2004.
45 1000.00 - + + a 100.00 - ++ a + a en d- en 10.00 - ctl a E I 0> 1.00 - 0 a 0.10 - - 0.01 ~ a -e,---.-----.---.--r----.-----.---.--.------,-..,....,r-r--,..-----.---.-r----..J I I I I I 0.1 1.0 10.0 100.0 1000.0 log-seed density 2 Figure 2.11. Seed mass (mg) and mean seed density (seeds/m ) in the bird-dispersed seed rain ofnative (+) and alien (0) species.
+ 10 ---= + - - - ++ - - .!: + °-tOa "C... a .~ I 0> 0 1 - a
a I I I I I 0.1 1.0 10.0 100.0 1000.0 log-seed density 2 Figure 2.12. Seed width (mm) and mean seed density (seeds/m ) in the bird dispersed seed rain ofnative (+) and alien (0) species.
46 + - +
10 --= ++ - + .t=...... - +0 0) - c: 00 0 Q) - .... - 0 0) 0 -
o 1 --= - - - 0 "\--,--r-r'I--,--r-r'Ir-----r--.,...--,rr-1---r--.,--·...... -'1 0.1 1.0 10.0 100.0 1000.0 log-seed density 2 Figure 2.13. Seed length (mm) and mean seed density (seeds/m ) in the bird dispersed seed rain of native (+) and alien (0) species.
47 DISCUSSION
The results ofthis study demonstrate the magnitude ofalien species invasions into native forests. Alien species, in particular, a single species Clidemia hirta, dominated the total seed rain and dispersed seed rain in all vegetation types in the study area. Clidemia hirta dramatically influenced the results toward significantly greater densities ofseed from alien than native species in total seed rain and dispersed seed rain in all vegetation types in the study area. Regardless, seed densities from alien species remained greater than native species when Clidemia hirta data was removed from the total and dispersed seed rain. When vegetation types were viewed separately and Clidemia hirta data were removed, the densities ofseed from native species were greater than alien species in native and edge vegetation in the total and dispersed seed rain.
In this study, Clidemia hirta was an example ofthe invasion offleshy-fruited alien species with small seeds in mesic Hawaiian forest. Ofthe 12 bird-dispersed species recorded in this study, Clidemia hirta was the most abundant and widespread in the dispersed seed rain. Several factors could account for this dominance. Clidemia hirta is the most common shrub in the study site. Clidemia hirta may produce larger fruit crops ofrelatively small-sized seeds that, by sheer number, have a greater probability ofbeing deposited in seed traps, or, similar to other species are removed at higher rates by frugivores attracted to the abundant food source (Howe & Primack 1975; Izhaki 2002).
Although fruit crop sizes were not estimated for the species in this study, fruiting phenology ofspecies may account for the abundance ofthe bird-dispersed seed rain.
Individuals ofClidemia hirta consistently produced a greater percentage offruit year round than any other shrub in the study area. Frugivores have been shown to track
48 changes in availability ofimportant food supplies (Loiselle & Blake 2002; Price 2004) and may focus on particular species that produce fruit when most others are sterile (Howe
& Primack 1975). Since Clidemia hirta produces fruit throughout the year, it may be the staple food source ofthe frugivore diet in the study area supplemented by other species as they become seasonally available. Fruit ofClidemia hirta contain many hundreds of seeds ofsmall size, which is one ofthe common attributes ofweedy species (Swaine &
Hall 1983; Thompson 1992).
Seed from native species (2.1 % oftotal seed rain) are less abundant than seed from alien species (97.9% oftotal seed rain) in the study area. The dominance ofseed from all alien species in the total seed rain and dispersed seed rain, may be due to the sheer number ofreproductive individuals ofalien species in the study area.
Fragmentation ofnative forest has led to a limited number ofreproductive individuals from native species in a limited area, isolated in an otherwise continuous matrix ofalien dominated forest. Many more reproductive alien species than native species were present in the study site and the surrounding area. Therefore, the possible influx ofalien seeds from these individuals may be responsible for the vast number ofalien seed present in the seed rain. Ofthe 41 native flowering plant species found the study area, 32 species were reproductively active during the study period. However, seeds from only 10 (31 %) of these species were collected in total seed rain and dispersed seed rain. In contrast, 17
(85%) of20 alien flowering plant species found in study area were reproductively active during the study period. Seed from 76% ofthose species were collected in the total seed rain and 64% in the dispersed seed rain.
49 The greater relative density ofseed 'not-dispersed' versus 'dispersed' confum the expectations ofleptokurtic seed shadows for most species collected in the seed rain, with greatest densities ofseed occurring close to the seed source (Wilson & Traveset 2000).
There was a significantly greater (P< 0.05) density ofseed from native species dispersed into local (native) vegetation than into distant (alien) vegetation. In contrast, the density ofdispersed seed from alien species was significantly greater (P< 0.05) in distant vegetation (native vegetation) than in local (vegetation). The differences in the
2 distribution ofdispersed seed between native and alien species (X = 35.43, df= 2, P <
0.05) may be attributed to dispersal adaptations ofspecies. The majority ofseed from native species captured in the dispersed seed rain were from a single wind-dispersed species, Metrosideros polymorpha. The majority ofnative species in the study area have fleshy-fruits, and their seed should be dispersed by birds. The lack ofmany small seeded native species with fleshy fruits, such as Claoxylon sandwicense, Elaeocarpus bifidus,
Coprosmajiliosa and Hedyotis terminalis, in the total and dispersed seed rain was alarming. Leptokurtic seed shadows may be exaggerated due to disperser limitation in many native species with large seeds and fleshy fruit. In other studies, the lack of appropriate seed dispersers and edge effects appear to limit disemination ofnative seed away from the primary seed source (Crist et al. 1992; Johnson et al. 1992; McConkey &
Drake 2002).
The majority ofseed from alien species captured in the dispersed seed rain were dispersed by birds. Ofthe six aliens (Clidemia hirta, Passiflora edulis, Psidium guajava,
Rubus rosifolius, Schinus terebinthifolius, and Spathodea campanulata) with greater densities ofseed collected farther from rather than close to the seed source have fleshy
50 fruits and rely primarily on birds for seed dispersal except Spathodea campanulata. Since
seed from these species were successfully dispersed away from the parent plant,
dispersability may not be limited in the study area by seed size or the current set ofseed
dispersers.
The sizes ofdispersed seed may be directly related to frugivore size (Jordano
2000). Seed dispersal by birds is limited, in part, by body size and gape width ofthe bird species, which may in turn influence the evolution offruit and seed size (Jordano 2000).
Birds may prefer to consume fruits with smaller seed size as most birds have a size limit in which the handling costs outweigh the benefits offruit and seed consumption (Martin
1985; Levey 1987; Jordano 2000;). Ofthe bird-dispersed species, there was a negative relationship between seed size and the number ofseed being dispersed by birds (seed mass (rs = -0.775, P = 0.002), seed length (rs = -0.868, P < 0.001), seed width (rs =
0.923, P < 0.001)). Seed ofnative species, on average, were larger than seed ofalien species at the study site. Therefore, dispersability oflarge-seeded native species may be a limited by the current set ofseed dispersers in the study area.
Since the arrival ofhumans, the composition ofthe avian fauna has changed drastically in all environments throughout the entire Hawaiian archipelago (Olson &
James 1982; Stone 1985). Native bird assemblages have been replaced with alien bird assemblages (Stone 1985). The lack offleshy-fruited native species being dispersed by birds may be directly related to the loss or change in pollinator and seed disperser assemblages (Temple 1977; Benitez-Malvido 1998). Only two native birds were sighted in the study area, the 'Amakihi (Hemignathus virens chloris) and the 'Elepaio
(Chasiempis sandwichensis gayi). Both species are predominantly insectivorous (Pratt et
51 al. 1987). More importantly, the study site is devoid ofnative bird species that may formerly have contributed to the dissemination ofseeds, such as flightless birds and a few ofthe honeycreepers (Olson & James 1982; James 1995; Steadman 1995). Though it is impossible to determine the role these extinct species played in plant communities in the
Hawaiian Islands and similar insular ecosystems such as New Zealand and Tonga, the abundance offleshy-fruited taxa suggests that some ofthese extinct birds would have played an important role in the dispersal offleshy-fruited species (Wagner et al. 1999;
McConkey & Drake 2002). It is also more likely that these extinct large-bodied bird species could have consumed and dispersed seed from fleshy-fruited, large-seeded native species, many ofwhich are scarcely being dispersed, ifat all, by the current assemblage ofalien avian fauna. One ofthe most abundant and reproductively active native plant species in the study area was Pouteria sandwicensis. It is a fleshy-fruited species with the largest seed ofany native species at the study site. Pouteria sandwicensis was not being dispersed by birds in the study area; instead, seeds dropped to the ground and likely rolled or were washed away from the parent plant.
The replacement ofnative birds by alien ones could also mean the loss of potential pollinators and lead to a reduction in amount ofnative seed available to the seed rain ofthe original vegetation (Temple 1977; Benitez-Malvido 1998).
Plant phenology and fruit abundance are other important factors in the dispersal of seeds by birds (Jordano 2000). In this study, species with smaller seed such as, Clidemia hirta and Rubus rosifolius may be more abundant in the bird-dispersed seed rain because they are continuously available as a food source for birds. Large-seeded species in the study area, were infrequent in the bird-dispersed seed rain and tend to produce fruit on a
52 seasonal basis (Figure B.I-B.6, Appendix B). These seasonal fruits may supplement the birds' diet when available (Howe & Primack 1975).
The edge often plays a significant role as a barrier to the dissemination ofseeds among vegetation types in fragmented forest (Crist et al. 1992; Johnson et al. 1992).
Edges bounding forest fragments and disturbed areas may regulate the distribution of resources and movement oforganisms between them (Crist et al. 1992; Johnson et al.
1992), thus altering the abundance and distribution oforganisms across the landscape
(Janzen 1983; Mills 1995; Murcia 1995). In this study, the edge did not have a dramatic effect on the dissemination ofseed among vegetation types, since vegetation types were different in composition rather than structure.
With time, the location and structure ofedges may change (Harper 1977; Matlack
1994b). The vegetation structure and composition may transform to alien-dominated vegetation as a greater density ofseed and seedlings from alien species than native species occupy the edge (Lovejoy et al. 1984; Malcom 1994; Murcia 1995). The location ofthe edge may shift into the native vegetation (Matlack 1994b; Benitez-Malvido 1998).
The rate ofencroachment ofedge and alien vegetation into native vegetation was not included in this study due to the short period oftime allotted, but this effect has been documented in other studies (Burton & Bazzaz 1991; Kapos 1989; Lovejoy et al. 1984;
Malcom 1994; Murcia 1995; Sizer 1992).
53 Conclusion
Clidemia hirta is a prime example ofinvasion by a fleshy-fruited and small seeded alien species. The high densities ofseed from Clidemia hirta also emphasizes the importance ofbird-dispersal as an effective mode ofplant invasion into distant vegetation. Seed dispersal by frugivorous birds can lead to the homogenization ofplant communities over an entire region (Debussche et al. 1982). The greater relative abundance ofseedlings from alien species than native species in edge vegetation may be an indication ofthe encroachment ofedge vegetation into native forest fragments. Seed from native species may be subjected to greater levels ofpredation as the majority of seed falls directly under the parent trees (Howe et al. 1985; Chapman & Chapman 1996;
Wenny 2000). This may exaggerate the already limited number ofnative seedlings. The inundation ofnative forests by alien species has dramatically altered many native forests to a possibly irreversible state throughout the Hawaiian Islands (Cuddihy & Stone 1990;
Smith & Tunison 1992) and the mesic forest fragment at Kalua'a may not be an exception. Conservationists, land and resource managers, and others interested in protecting native forest need to pay strict attention to the dispersability ofalien species and the dynamics with dispersal vectors. Alien species with effective seed dissemination into distant vegetation should be ofpriority for control; otherwise the alteration ofnative vegetation by those species may be inevitable.
54 CHAPTER 3: SEED BANK DYNAMICS
INTRODUCTION
A "seed bank" is an aggregation ofungerminated, viable seed present on or in the soil or associated litter (Baker 1989; Leck 1989). The composition ofthe soil seed bank is determined by input and loss ofseed (Leck 1989). Three general seed bank syndromes exist, as well as variations ofeach: transient, persistent and pseudo-persistent (Cook
1979, 1980; Garwood 1989; Harper 1977; Louda 1989). In the Hawaiian Islands, some alien species tend to form persistent seed banks (Drake 1998), which suggests that these aliens will increase in abundance in the vegetation, especially in fragmented vegetation.
Frequent disturbance can eliminate or drastically reduce native seed banks
(Young et ai. 1987). Restoration success ofnative vegetation depends on the establishment ofspecies in the under-story (Lugo 1992), which in turn depends on what seed are present in the seed bank at the time ofthe restoration activity, as well as what seed are brought in by the wind and seed dispersers (Robinson & Handel 1993; Smith
1975; Young et ai. 1987). Therefore, soil seed bank composition and seed dispersal play extremely important roles in the restoration ofplant communities in deforested and fragmented areas (McClanahan & Wolf 1993). Forest management should minimize disturbances, to prevent germination ofcompetitive alien species from buried seed
(Bossuyt et ai. 2002).
55 Seed Size
There is a diverse range ofshapes and sizes ofseed among plant species ofthe
world. Variation in seed size represents a fundamental trade-off between producing more
small seeds versus fewer large seed (Leishman et al. 2000). In general, small seed (seed
mass < 1.5 mg) rather than large seed (seed mass ~ 1.5 mg) are able to escape predation
and tend to dominate the soil seed bank. Small seed are usually persistent and are more
likely to find suitable microsites for germination and growth than large seed (Harper et
al. 1970; Leishman et al. 2000; Peco et al. 2003). Dominance ofsmall seed in the soil
seed bank may be due to high per-captia survival or due to more small seed being produced than large seed. In contrast, large seeds are frequently removed by seed
predators and less likely to be incorporated into a persistent seed bank. Large seed are usually viable only for a short period (Leishman et al. 2000; Peco et at. 2003). But,
seedlings produced from large seed are able to tolerate drought, herbivory, and shade better than many seedlings from small seed (Thompson 1987; Leishman et at. 2000).
Lack ofRecruitment
Two views concerning the role ofrecruitment for forest dynamics are presented.
The first view is that populations are "dispersal limited," with low and uncertain seed
supply being the cause for absence or rarity (Fleming & Heithaus 1981; Hughes & Fahey
1988; Schupp 1990). A second view ascribes a more limited role in the dynamics of
forests to seed supply. The focus shifts to distribution and quality ofmicrosites for
seedling establishment (Houle 1992; Peterson & Pickett 1990) and factors affecting growth and mortality in seed banks and seedling stages (Burton & Bazzaz 1991; Reader
56 & Buck 1991). Often, the rate ofrecruitment in plant populations is dependent on both microsite availability and seed availability (Crawley 1990; Ericksson & Ehrlen 1992;
Fowler 1986; Hughes et al. 1988; Klinkhamer & de long 1989; Louda 1982; Louda
1983; Peart 1989). Microsite and seed availability are determined by factors such as seed dispersal, seed bank dynamics, seed predation, disturbance frequency, or herbivory
(Fowler 1986; Peart 1989; Reader & Buck 1991). Here, I investigated soil seed bank dynamics, a factor limiting seed availability.
This study is ofparticular importance in the Hawaiian Islands for a few reasons.
First, few studies ifany, have been conducted investigating seed limitation in native forests. Second, the successful management ofHawaii's unique species and ecosystems rely on knowledge gained from primary ecological research and its incorporation into conservation practices. Ecologically based practices allow land managers to quickly achieve goals. Information regarding soil seed bank dynamics may also provide insight into the long-term viability ofa species (i.e. effective and/or viable population size) or community and the likelihood ofextinction. I investigated the composition ofthe soil seed bank in native, alien and edge vegetation types by species and relationship, ifany, between seed size and the density ofseed in the soil seed bank. I classified functional seed bank types for species with the necessary data.
57 METHODS
Study Site
This study was conducted along the Kalua'a drainage within The Nature
Conservancy ofHawaii's (TNCH) Honouliuli Preserve, O'ahu, Hawai'i (Figure 3.1).
The 1,494-hectare preserve is situated between 366-945 m (1,200 and 3,100 feet) elevation on the eastern slope ofthe Wai'anae Mountain Range. The range ofmoisture conditions along a continuum ofrelatively dry habitats contribute to the Wai'anae
Mountains being among the most biologically diverse in the entire Hawaiian archipelago
(Wagner et al. 1999). Honouliuli is home to 70 rare and endangered native plant and animal species and six native communities. The native natural communities are fragmented and occupy small to large pockets ofthe preserve.
58 Trails 1_ Kaiullia rence J_--JI Study site
Figure 3.1. Study area within Kalua'a drainage, Honouliuli Preserve, The Nature Conservancy Hawaii. (UTM coordinates 593322.76E, 2373405N)
59 Large-scale modification to the lands ofHonouliuli began between 1815 and
1830, during the sandalwood trade (Cuddihy & Stone 1990; Kirch 1982). This disturbance was accompanied by the introduction oflivestock, such as cattle and goats, that had free range and devastated much ofthe native vegetation (Honouliuli Preserve
Master Plan 2001). In 1877, when James Campbell purchased the land that now includes
Honouliuli Preserve, he reportedly drove 32,347 wild cattle offthe land (Honouliuli
Preserve Master Plan 2001). The wild cattle were then replaced with higher quality short homed cattle for Campbell's beefranch. Prior to heavy human use, the native forests of
Honouliuli are believed to have functioned as a healthy watershed (Honouliuli Preserve
Master Plan 2001). However, by the early 1900s, most ofHonouliuli's forests had been destroyed after decades oftrampling hooves, sandalwood harvesting, and agriculture.
Major reforestation efforts in Honouliuli occurred in the late 1920s to early 1940s. Within a seven-year period (1934-41), nearly 1.5 million trees (mostly fast-growing non-natives) were planted along the mid-elevation slopesofHonouliuli by Civilian Conservation
Corps. This was the largest concentration oftree planting on 0'abu. The main stresses affecting Honouliuli Preserve are habitat loss and fragmentation, change in composition/structure ofhabitat, and change in fire patterns (Honouliuli Preserve Master
Plan 2001).
Kalua'a comprises the northern portion ofthe preserve and is classified as low elevation dry to mesic forest habitat (Wagner et al. 1999). The annual rainfall is approximately 1,000 mm (40 inches) (Honouliuli Preserve Master Plan 2001). At the end of2002, TNCH completed the construction ofa 108-acre fence protecting a portion of dry-mesic forest, specifically classified as Oahu diverse mesic forest, within Kalua'a
60 drainage between 600-800 m in elevation (1800-2400 ft). The study site located within this area at UTM coordinates 593322.76E, 2373405N. The site includes a 2-hectare native forest fragment and the adjacent, alien, matrix vegetation to the east (down slope, toward the mouth ofthe valley). The native forest fragment is surround by alien dominated vegetation.
TNCH personnel conduct restoration activities and poison control for rodents within the native forest fragment. Restoration ofrare and endangered plant species and rodent control began in January 2002. Potentially large populations ofRattus exulans and/or R. raltus exist throughout the drainage, although only six bait stations containing rodenticide are located throughout the native forest fragment. The seed bank portions of the study were conducted in the native forest fragment and the adjacent non-native vegetation.
Measurement ofSeed Banks Under Native Canopy, Alien Canopy, andAlong the Edge
The seed bank was sampled under both native and alien canopy as well as within the edge by soil coring. Soil cores were taken quarterly (every 3 months) for a year, following weeks 13, 26, 39 and 52 ofseed rain sampling (see Chapter 2). Experimental design described by Drake (1998) was used, in which the area around each seed rain trap was divided into four quadrants (see Chapter 2, Figure 2.2). A soil core was taken from a different quadrant every 13 weeks from a point one meter from the seed trap (Figure 3.2).
In total, 184 soil cores including leaflitter were taken at each sampling interval. Cores were 5.0 em in diameter and 5.0 em in depth. The total area sampled by 184 cores was
2 0.36 m •
61 • Seed tra.p
I 1 mle11gth
Soil core • Figure 3.2. Soil core design. Blue circle represents a soil core. One core was taken at a random point along a different I-meter length bisect from seed trap at 13 week intervals. Diagram is not to scale.
All soil core collections were passed through a sieve, and large pieces oflitter, rock, and roots were discarded. Samples were spread over a 15 cm diameter plastic tray to a depth ofless than or equal to1.2 cm over l-cm ofpotting mix within 24 hours of collection. Trays were placed on germination benches in a cover outdoor area that receives partial sun and shade. The germination area consisted ofplastic tables 3 ft offthe ground with a sprinkler system for each table. The seed trays were watered daily by an automatic sprinkler system and/or by hand. Five control trays ofpotting mix were randomly distributed among the samples in order to monitor for any contamination from the potting mix or from seed dispersed by wind and/or birds in the germination area. All identifiable seedlings that emerged within 13 weeks were identified to species, counted and removed from the trays. Any unidentifiable seedlings were transplanted and grown to an identifiable size.
62 Seed BankAnalysis
Data recorded from the seed germination trays were used to quantify the difference in seed bank composition in native, edge, and alien vegetation types. Total emerged seedling numbers from soil cores were converted to seedling densities
2 (seedlings/m ). Differences in the mean density ofseedlings ofnative and ofalien species among vegetation types were assessed using a Kruskal-Wallis test. A Chi-squared test was used to identify differences in the proportion ofdispersed seed from native or alien species, in each vegetation type. Species richness ofemerged seedlings from the soil seed bank was also compared among the three vegetation types using a Chi-squared test. Data on seed dispersal (see Chapter 2), phenology (see Appendix B) and seasonal changes in the soil seed bank were used to classify species into one ofthree general seed bank syndromes: transient, persistent, or pseudo-persistent (Garwood 1989). Only species with data on seed dispersal and/or phenology and seasonal changes in species seed bank were used in these analyses.
Seed Size Measurements
Seed collected from soil cores were not available for direct measurement and analysis, therefore species vouchers were used to determine the size ofseed found in the soil seed bank (measurements include; seed mass (mg), greatest length (mm) and greatest width (mm)). Here, the term 'seed' typically refers to diaspore, the unit ofdispersal, and may include structures such as endocarps. The size ofseed from species present in the soil seed bank, but not represented in the existing vegetation, was determined by collecting fruit and seed from alternative sources (i.e. other natural populations in the
63 closest proximity). Seed sizes were determined as seedlings emerged and were identified.
Measurements were taken on 15 randomly selected seed from each species from seed captured in seed traps or species vouchers. All emerged seedlings were then categorized as either small (mass < 1.5 mg, length < 3.0 mm, and width < 2.5 mm) or large (mass ~
1.5 mg, length ~ 3.0 mm, and width ~ 2.5 mm). Spearman's rank correlation was used to test for relationships between seed mass, length, width, and total numbers ofemerged seedlings from soil cores.
64 RESULTS
A total of51,940 seedlings from 18 flowering plant species were found in184 soil cores in native, edge and alien vegetation at Kalua'a from September 2003 to June 2004
(Table 3.1). Ofthe emerged seedlings, 257 (0.5%) were native species, 51,678 (99.5%) were alien species and 5 remained unidentifiable (Table 3.1). Ofthe 13 alien species, four species, Buddleia asiatica, Hypochoeris glabra, Pluchea symphytifolia, and Solanum americana, were only found in the soil seed bank and not in the vegetation at the study site (Table 3.1 & Table A.3, Appendix A). A single alien species, Clidemia hirta,
2 dominated the soil seed bank with over 99% ofthe mean seedling density (seedlings/m )
(Table 3.1). A significantly greater density ofalien seedlings than native was found in the soil seed bank in all vegetation types (Paired t-test; P < 0.05) (Table 3.1). Excluding
Clidemia hirta, the differences between native and alien species were not significantly different in all vegetation types (Paired t-test; P> 0.05) (Table 3.1, Figure 3.3).
The composition ofspecies among vegetation types in the soil seed bank was relatively uniform (Table 3.1). However, the diversity ofspecies represented in the soil seed bank was low considering the relatively high diversity ofvegetation at the study site
(Table 3.1; Table A.3, Appendix A).
65 As expected, significantly greater densities ofnative seedlings emerged from soil cores collected in local (native) vegetation than distant (alien) vegetation (Table 3.1)
(Kruskal-Wallis, H= 9.739, df= 2, P < 0.05). Similarly, significantly greater densities of alien seedlings (excluding Clidemia hirta) emerged from soil cores collected in local
(alien) vegetation than distant (native) vegetation (Kruskal-Wallis, H= 8.27, df= 2, P <
0.05) (Table 3.1). In contrast, ifClidemia hirta is included, significantly greater densities ofalien seedlings were found in distant (native) vegetation than in local (alien) vegetation
(Table 3.1) (Kruskal-Wallis, H= 40.411, df=2, P < 0.05). The densities ofseedlings between edge and distant vegetation were not significantly different for either species group. Results from a Chi-square test (including Clidemia: X2 = 108.4, df=2, P < 0.05; excluding Clidemia: X2 = 6.89, df=2, P < 0.05) provided strong evidence that the distribution ofseedlings among natives was different from among aliens (Table 3.1,
Figure 3.4).
66 Table 3.1. Relative mean density (ReI. %) and mean density (seedlings/m2 ± SE) ofseedlings per soil core in native, edge and alien vegetation) and percentage oftotal seedling presence for all species collected in 184 soil seed cores in Kalua'a drainage from September 2003 to June 2004. An asterisk * represents species only found in the soil seed bank (not found in the vegetation or seed rain) at Kalua'a.
Native Edge Alien Species Name Status % Total ReI. % Mean ReI. % Mean ReI. % Mean
Clidemia hirta Alien 99.22 43148 ± 9415 99.13 34540 ± 8454 98.94 32110 ± 8530 99.1 Pipturus albidus Native 0.25 106.8 ± 49.6 0.29 97.2 ± 59.9 0.28 91.8 ± 37.1 0.27 Toona ciliata Alien 0.03 19.3 ± 12.1 0.19 71.2 ± 50.3 0.36 116.9 ± 86.6 0.18
Acacia koa Native 0.18 158 ± 102 0.1 61.5 ± 44.4 0.37 17.9±3.6 0.22 0\ -.....l Buddleia asiatica* Alien 0.04 2.2 ± 1.7 0.07 25.9 ± 18.3 0.16 52.2 ± 43.3 0.09
Rubus rosifolius Alien 8.71 x 10-3 2.3 ± 1.7 0.05 16.2 ± 3.2 0.01 3.6 ± 2.1 0.02
Passiflora suberosa Alien 0.01 6.1±3.1 0.03 9.7 ±6.2 0.03 12.6 ± 4.5 0.02 Oxalis corniculata Alien 4.35 x 10-3 2.4 ± 1.7 9.33 x 10-3 3.2 ± 3.2 0.04 10.8 ± 6.2 0.02 Hypochoeris glabra* Alien 4.35 x 10-3 2.2 ± 1.7 9.33 x 10-3 3.2 ± 3.2 0.03 9.0 ± 9.0 0.01 Psidium cattleianum Alien 0.0 0.4 ± 0.4 0.0 0.0 0.03 10.8± 10.8 0.01
Pluchea symphytifolia* Alien 4.35 x 10-3 2.3 ± 1.7 0.02 3.2± 3.2 0.02 7.2 ± 5.1 0.01 Aleurites moluccana Alien 4.35 x 10-3 2.1 ± 1.7 0.0 0.0 0.02 7.2 ± 7.2 9.63 x 10-3
3 Psidium guajava Alien 0.02 9.3 ± 9.3 0.0 0.0 0.0 0.0 9.63 X 10- 3 Unidentified spp. 8.71 x 10-3 3.8 ± 2.2 0.0 0.0 0.02 5.4 ± 3.4 9.63 x 10- Solanum americana* Alien 8.71x 10-3 3.8 ±2.2 9.33 x 10-3 0.0 5.5 x 10-3 1.8 ± 1.8 7.7 x 10-3 Table 3.1. Continued. Relative mean density (ReI. %) and mean density (seedlings/m2 ± SE) ofseedlings per soil core in native, edge and alien vegetation) and percentage oftotal seedling presence for all species collected in 184 soil seed cores in Kalua'a drainage from September 2003 to June 2004. An asterisk * represents species only found in the soil seed bank (not found in the vegetation or seed rain) at Kalua'a.
Native Edge Alien Species Name Status % Total ReI. % Mean ReI. % Mean ReI. % Mean Canavalia galeata Native 0.0 0.2 ± 0.2 0.02 0.0 0.0 6.5 ±6.5 3.85 x 10-3 3 3 Charpentiera obovata Native 0.0 0.1 ±0.1 9.33 x 10- 3.2 ± 3.2 0.0 0.0 1.93 X 10- 3 3 Lantana camara Alien 0.0 0.1 ±0.1 0.0 0.0 5.48 X 10- 1.8 ± 1.8 1.93 x 10- 3 3 Morinda trimera Native 4.35 x 10- 1.9 ± 1.9 0.0 0.0 0.0 0.0 1.93 X 10-
Native species 0.64 267.0 ± 100.0 0.49 168.0 ± 104.0 0.33 109.7 ± 40.2 0.5 0'\ 00 Alien species 99.36 41062 ± 2405 99.51 34543 ± 2905 99.67 32720 ± 2465 99.5 (+Clidemia hirta) Alien species 0.14 59.4 ± 18.3 0.38 132.8 ± 34.5 0.71 232.1 ±37.8 0.39 (-Clidemia hirta) 0.8% t/) C) ~ 0.6% CI) o Native species
I 0.4% • Alien species i (-Clidemia) E 0.2% CI) I 0.0% Native Edge Alien Total I
Vegetation Types . Figure 3.3. Percentage ofemerged seedlings for native and alien species in different vegetation types in Kalua'a drainage from June 2003 to May 2004. Note: this is a subset ofalien species data; Clidemia hirta is not included.
100000 o Native species 10000 ~ t/) IZlAlien c 1000 species CI) I 't:I I (+CH) I C I • I ca 100 Q) i .Allen I
E II· species I 10 I (-CH) I 1 local edge distant Vegetation Type
Figure 3.4. Mean density ofseedlings from native and alien species in Kalua'a drainage from June 2003 to May 2004. +CH= including Clidemia hirta; -CH= excluding Clidemia hirta. 'Local' = native vegetation for native species; local = alien vegetation for alien species. 'Distant' = native vegetation for alien species; distant = alien vegetation for native species). Chi-square test (including CH: X2 = 108.4, df=2, P < 0.05; excluding CH: X2 = 6.89, df=2, P < 0.05) provided strong evidence that the distribution ofseedling density among natives was different from among aliens.
69 Species richness ofseedlings per soil seed core ranged from 0-4 native species and 0-2 alien species within native vegetation, 0-2 native species and 0-3 alien species within edge vegetation, and 0-2 native species and 0-6 alien species within alien vegetation. Results from a Chi-squares test (X2 =22.58, df=l, P < 0.05) provided evidence that the distribution ofspecies in the soil ofnative and alien vegetation was different between native and alien (Table 3.2).
Table 3.2. Mean species richness (± 0.1 SE) per soil seed core in native and alien vegetation types.
Category Native Edge Alien -..,------,.---,------Native species 0.28 0.18 0.11 Alien species 0.98 1.0 1.12
70 All plant species have a soil seed bank syndrome, but only six plant species in this study were abundant enough in the soil seed bank, seed rain (see Chapter 2), and/or represented by phenology data (see Appendix B) to be classified as having a persistent or pseudo-persistent soil seed bank. The remaining species represented in this study may form transient soil seed banks. The short duration ofthis study may be one ofthe limitations to classifying soil seed bank syndromes.
Three species formed persistent soil seed banks, Clidemia hirta (alien), Acacia koa (native), and Pipturus albidus (native) (Figure 3.5). In general, seed densities in the soil seed bank were greater than seed rain, suggesting that continual presence in the soil was not dependent on continued input from seed rain and that longevity in the soil was greater than one year. Three other alien species formed pseudo-persistent soil seed banks:
Toona ciliate, Oxalis corniculata, and Rubus rosifolius (Figure 3.6). In general, seed densities in the seed bank tended to be lower than in the seed rain for the corresponding quarter and fluctuate with densities in the seed rain or fruiting periods. The remaining species in this study, by definition, may have transient soil seed banks since seed densities in the soil were low or inconsistent and only present directly following seed rain and fruiting periods (Figure 3.7).
71 Clidemia hirta JlD ***** ******* &aD *********************** Acacia koa 2&1
2m q:[(()
:n:m 1&1
2IJXD 1m
1COJJ 51] 0 I] SEPT .~ ce::: SEPT DEC WlR JUNE 00 ~ ~ Pipturus albidus 29J *********** xo
1SJ
10)
g)
0 $'T
Months Figure 3.5. Seed profiles for species in a dry-mesic Hawaiian forest with persistent seed banks. Fruiting periods are denoted by asterisks. Solid columns represent seed rain. Mean density values for the seed rain represent seed rain for a 13-week period ending in the month labeled on the axis (seedJm2 ± SE). Striped columns represent seed bank. Mean density values for the seed bank represent the number ofgerminants emerging from soil samples collected at the end ofthe corresponding seed rain interval (seedlings/m2 ± SE).
72 Toona ciliata Oxalis cornicutata 40J J) """""""" """""""""""" """""""""""""""""""""""""" 16 3JJ 12 :;m 8
1CD 4
0 0 H:f'r
B00 5 ~ Rubus rosijolius 25 ********************* :.;{)
15
10
5
0
Months
Figure 3.6. Seed profiles for species in a dry-mesic Hawaiian forest with pseudo persistent seed banks. Fruiting periods are denoted by asterisks. Solid columns represent seed rain. Mean density values for the seed rain represent seed rain for a I3-week period ending in the month labeled on the axis (seeds/m2 ± SE). Striped columns represent seed bank. Mean density values for the seed bank represent the number of germinants emerging from soil samples collected at the end ofthe corresponding seed rain interval (seedlings/m2 ± SE). Note: Oxalis corniculata may form a pseudo-persistent or persistent soil seed bank.
73 Aleurites moluccana Passiflora suberosa ************************ ::ilJJ ************************ 16 1:)) 12 100
o
Psidium cattleianum Psidium guajava 35 *** 3J * ***** ** 3J **** 25
25 :: Pouteria sandwicensis Psychotria mariniana 8 ************************* 10 *************** ****** 6 4 2 0+----..-- Figure 3.7. Seed profiles for species in a dry-mesic Hawaiian forest with transient seed banks. Fruiting periods are denoted by asterisks. Solid columns represent the seed rain. Mean density values for the seed rain represent seed rain for a 13-week period ending in the month labeled on the axis (seeds/m2 ± SE). Striped columns represent the seed bank. Mean density values for the seed bank represent the number ofgenninants emerging from soil samples collected at the end ofthe corresponding seed rain interval (seedlings/m2 ± SE). 74 The density ofseed from native species in the soil seed bank was less than in the seed rain (Figure 3.8). In contrast, the densities ofseed for alien species in the soil seed bank were generally greater than in the seed rain (Figure 3.8). Interestingly, when seed densities for Clidemia hirta are removed from the analysis, the density ofseed from alien species in the soil seed bank were less than in the seed rain (Figure 3.8). This suggests a greater longevity ofClidemia hirta all other alien species in the soil relative to native species. AJ1 alien species Alien species w/o 1800 70000 Clidemia hirta 60000 1500 50000 1200 40000 000 30000 000 20000 10000 3)0 0 0 ..0 SEJ=lT DEC MM JLNE SEJ=lT DEC .-m !Ii t=I am AJ1 native species 9J)) 4000 3D) XOJ 1000 0 S8'T DEC Months Figure 3.8. Summary data for seed profiles for native, alien species and alien species excluding Clidemia hirta in a dry-mesic Hawaiian forest. Solid columns represent the seed rain. Mean density values for the seed rain represent seed rain for a 13-week period ending in the month labeled on the axis (seeds/m2 ± SE). Striped columns represent the seed bank. Mean density values for the seed bank represent the number ofgerminants emerging from soil samples collected at the end ofthe corresponding seed rain interval (seedlings/m2 ± SE). . 75 Seed Size andSoil Seed Bank Dynamics 51,940 seedlings emerged from the transplanted184 soil cores (Table 3.1) from September 2003 to June 2004. Ofthose species, 51,698 (99.5%) were from small seeded species, 237 (0.5%) seedlings were from large seeded species and 5 remained unidentifiable. The results for small seeded species were dominated by Clidemia hirta (99.2% ofthe total emerged seedlings) (Table 3.1). Including Clidemia hirta, significantly greater densities ofsmall seed than large seed (Paired t-test, P < 0.05) were found in the soil seed bank in all vegetation types (Table 3.3). In contrast, excluding Clidemia hirta, densities ofsmall and large seed were not significantly different (Paired t-test, P > 0.05) in all vegetation types (Table 3.3). Table 3.3. Mean density (seedlings/m2 ± SE) ofgerminated seedlings per soil core in native, edge and alien vegetation for 184 soil seed cores in Kalua'a drainage from September 2003 to June 2004. Species Total Native Edge Alien Small seeded 36742.0 (4831.0) 41134.0 (2409.0) 34573.0 (2906.0) 32668.0 (2469.0) (+Clidemia hirta) Small seeded 143.0 (25.7) 134.5 (44.2) 129.5 (54.4) 165.5 (45.6) (-Clidemia hirta) Large seeded 168.2 (54.7) 187.1 (54.4) 139.2 (38.1) 161.9 (32.2) 76 Species with small seeds comprised 56% ofthe soil seed bank while 44% were large-seeded species. Ofthe small-seeded species, 20% were native and 80% were alien species (Table 3.4). Ofthe large-seeded species, 38% were from native species and 62% were from alien species (Table 3.4). There was a negative relationship between numbers ofemerged seedlings in soil cores and seed mass (rs = -0.363, P = 0.152), seed length (rs = -0.322, P = 0.208), seed width (rs = -0.226, P = 0.384), though the relationships were not significant. Table 3.4. Mean (± 1 SE) seed mass (mg), seed length (mm) and width (mm) ofall species emerged from soil cores at Kalua'a drainage from June 2003 to May 2004. Sample sizes for each species are the same (n=15). Native species are identified by an asterisk (*). Dry mass ofseed Greatest Greatest width # d Seed Category w/o pulp length w/o /I emerge w(~p seedlings (mg) pulp (mm) Clidemia hirta 0.006 (0.001) 0.7 (0.03) 0.5 (0.05) 51,475 Pipturus albidus* 0.02 (0.01) 1.0 (0.3) 0.7 (0.06) 139 Acacia koa* 70.9 (9.01) 9.49 (0.08) 5.25 (0.7) 114 Toona ciliata 4.87 (1.91) 16.25 (3.89) 4.25 (0.79) 93 Buddleia asiatica 0.65 (0.04) 0.9 (0.1) 0.85 (0.06) 46 Passiflora suberosa 5.2 (1.21) 4.4 (0.10) 2.7 (0.11) 11 Oxalis corniculata 1.1 (0.06) 1.1 (0.2) 0.9 (0.2) 9 Rubus rosifolius 0.5 (0.02) 1.3 (0.09) 0.85 (0.02) 9 Hypochoeris glabra 0.008 (0.001) 0.9 (0.02) 0.7 (0.08) 7 Pluchea symphytifolia 1.4 (0.05) 1.2 (0.05) 0.5 (0.01) 7 Psidium cattleianum 92.3 (11.89) 6.5 (0.08) 3.6 (0.09) 6 Aleurites moluccana 11300.0 (7.9) 14.6 (0.09) 9.5 (0.09) 5 Psidium guajava 335.8 (4.54) 4.3 (0.11) 3.4 (0.10) 5 Solanum americanum 0.65 (0.05) 1.3 (0.1) 0.9 (0.05) 4 Charpentiera obovata* 0.85 (0.03) 1.6 (0.2) 0.85 (0.02) 1 Lantana camara 0.8 (0.1) 1.5 (0.3) 0.8 (0.03) 1 Morinda trimera* 100.7 (10.3) 10.2 (0.1) 6.4 (0.2) 1 Small seeded Native species 140 Small seeded Alien species (+Clidemia hirta) 51,558 Small seeded Alien species (-Clidemia hirta) 83 Large seeded Native species 115 Large seeded Alien species 120 77 The three species forming a persistent soil seed bank consisted ofa single large seeded species (Acacia koa) and two small-seeded species (Pipturus albidus and Clidemia hirta) (Figure 3.3). The three species forming a pseudo-persistent soil seed bank also consisted ofa single large-seeded species (Toona ciliata) and two small-seeded species (Oxalis corniculata and Rubus rosifolius) (Figure 3.4). Transient soil seed banks were formed by species ofvarious seed size. Greater densities ofsmall seed were generally found in the soil seed bank than in the seed rain (Figure 3.9). In contrast, seed oflarge size had a greater in density in the seed rain than in the seed bank (Figure 3.9). Interestingly, when seed densities for Clidemia hirta are removed, the density ofsmall seed in the soil seed bank were generally less than in the seed rain (Figure 3.9). This suggests the longevity and dominance ofClidemia hirta rather than all small-seeded species over large-seeded species in the soil. 78 7OJ)) Small seed 5250 Small seed w/o Clidemia hirta a:rm 4&)0 sxm 3750 40DJ 3000 3XO) 2250 m:o 1500 1011l 750 0 0 SB'T CEC M.!lR J..I\E SB"T DB: MAR JUNE B00 ii CI 1800 Large seed 1600 1400 1200 1000 800 600 400 : Months Figure 3.9. Summary data for seed profiles for small- and large-seeded species in a dry-mesic Hawaiian forest. Solid columns represent the seed rain. Mean density values for the seed rain represent seed rain for a 13-week period ending in the month labeled on the axis (seeds/m2 ± SE). Striped columns represent the seed bank. Mean density values for the seed bank represent the number ofgerminants emerging from soil samples collected at the end ofthe corresponding seed rain interval (seedlings/m2 ± SE). 79 DISCUSSION The results ofthis study demonstrate the magnitude ofan alien species invasion in to native forests. The composition ofthe soil seed bank is determined by input from the seed rain within a community and from distant seed sources (Leek 1989). In vegetation types at Kalua'a, the alien species Clidemia hirta dominated the seed rain (see Chapter 2) and the soil seed bank. Several factors could account for this dominance. The small seeds ofClidemia hirta form a persistent soil seed bank. Seeds ofClidemia hirta are tiny and may easily penetrate leaflitter and soil horizons and escape predation, as other small seeded species do (Harper et at. 1970; Louda 1982; Leishman et at. 2000; Peco et at. 2003). Also, small-seeded species due to the sheer number produced and dispersed may be dominant over large-seeded species. Excluding Clidemia hirta data, a greater density ofseedlings from native species than alien species was found in the soil seed bank in all vegetation types. This may be due to high density ofseedlings from two native species, Acacia koa and Pipturus atbidus. Both natives formed persistent soil seed banks. 80 Overall, the diversity ofthe soil seed bank was low compared to similar studies (Hopkins & Graham 1984; Drake 1998; Moles & Drake 1999). Only eighteen species were represented in the soil seed bank, ofwhich five were native. Poor representation of species in the soil seed bank may be the result ofrequirements not being met for breaking seed dormancy in the germination assay. It may also be due the conditions during the assay (i.e. light, temperature, and/or moisture) not being optimal for species. Also, some seedlings may have died in the germination trays before reaching an identifiable size. Though not tested in this study, a majority ofseed may be removed from the soil by predators before soil cores were collected. Seed produced by numerous native, woody species such as, Alyxia oliviformis, Antidesmaplatyphyllum, Bidens torta, Bobea elatior, Claoxylon sandwicense, Coprosma filiosa, Elaeocarpus bifidus, Hedyotis terminalis, Melicope sandwicensis, Metrosideros polymorpha, Pouteria sandwicensis, Psychotria mariniana, Psydrax odoratum, Pisonia brunoniana and Solanum sandwicense were continuously or typically seasonally available in the study area. Even though these species comprised 22.8% absolute cover in the total vegetation ofthe study area, they were completely absent from the seed bank. For these species, regeneration could be strongly affected by the availability ofappropriate microsites (Fleming & Heithaus 1981; Schupp 1990) in relation to seed production or susceptibility to seed predation. Necessary germination requirements and death ofseedlings prior to identification may also account for the absence ofthese species in the soil seed bank. Bulk germination in a 'greenhouse' environment is the simplest and fastest method ofestimating seed bank composition and density, but it may not provide the correct germination cue for all species. The requirements for breaking-dormancy are unique to individual species (Baskin & Baskin 81 2001) and may not be met in the homogeneous environment ofa greenhouse. Therefore, densities ofseed in the soil seed bank and soil seed bank syndromes presented here may not be entirely representative ofspecies occurrences in soil seed banks ofeach vegetation type. Also, many species may form transient soil seed banks that by definition are infrequent in the soil and only present directly following seed rain and fruiting periods (Louda 1989). The edge, as seen in the dispersal ofnative species (see Chapter 2), may function as a boundary limiting the dissemination ofnative seed into neighboring vegetation and incorporation into the soil seed bank. The density ofseed from native species in the soil seed bank decreased with greater distance from the major seed source ofthe native vegetation. The two most abundant native species in the soil seed bank, Acacia koa and Pipturus aZbidus, also followed this trend. In contrast, the seed density ofClidemia hirta increased with an increased distance away from local (alien) vegetation into distant (native) vegetation. These data, as well as the occurrence offour small-seeded alien species in the soil seed bank and not in the surrounding vegetation suggests that long distance dispersal oflight-weight seeds is an important factor contributing to the composition ofthe soil seed bank (Harper 1977; Cook 1980; Louda 1983). Soils beneath forests that are within dispersal distance ofdisturbed vegetation typically contain large seed banks ofweedy secondary species (Cheke et al. 1979; Young et aZ. 1987; Sem & Enright 1995). The soil seed bank in this study supports this pattern. The most successful plant invaders into disturbed areas are those species with seed attributes such as long-distance dispersal and long-lived seed banks (Swaine & Hall 1983; Young et al. 1987; Thompson 1992), such as Clidemia hirta. 82 Typically, germination and future vegetation at a disturbed site are dominated by the most abundant species in the seed bank (Swaine & Hall 1983; Lugo 1992). As disturbed sites arise, those species with propagules already present in the soil seed bank may have an advantage over other species (Harper 1977; Swaine & Hall 1983; Young et ai. 1987; Thompson 1992). The high density ofa particular species or set ofspecies in the soil seed bank does not automatically guarantee dominance in the germinants or future vegetation ofa disturbed site (Swaine & Hall 1983; Lugo 1992). But, it may be safe to speculate that as disturbance occurs in native forest and forest fragments in the Hawaiian Islands, alien species will contribute substantially to, and alter, the vegetation and community structure (Mederios 2004). The most common alien species in the soil seed bank at Kalua'a are typically common in disturbed sites throughout the Hawaiian Islands (Cuddihy & Stone 1990; Wagner et ai. 1990). A few alien species in the seed bank, Psidium cattieianum, Psidium guajava, and Lantana camara as well as Clidemia hirta, have the potential, once established, to completely alter native forest communities. Elsewhere in Hawaii, these species tend to rapidly invade disturbed areas and out compete native species (Cuddihy & Stone 1990). As the classification ofsoil seed bank syndrome is dependent on seed dispersal and/or phenology data, and the required data for all species was not available, few species were classified. Many ofthe alien species with small seeds, such as Buddieia asiatica, Piuchea symphytifolia, Solanum americanum, and Lantana camara typically form persistent soil seed banks (Drake 1998; Bossuyt et ai. 2002; Peco et al. 2003) but in this study remain unclassified. It was impossible to determine soil seed bank syndromes for 83 many native species due to their absence in the soil seed bank, which by definition may classify them as having transient soil seed banks. Nevertheless, the low density ofseeds observed for native species in the soil seed bank may imply the availability ofnative seed for regeneration is limited (Fleming & Heithaus 1981; Schupp 1990). With the knowledge ofseed rain and soil seed bank composition, some tentative predictions may be made about the potential composition of the regeneration that would follow forest disturbance at Kalua'a. The continuous dominance ofthe alien species, Clidemia hirfa, in the seed rain and seed bank implies that the encroachment ofthis species is in progress, altering the composition ofexisting native forest fragments. The addition and dissemination ofnative propagules into appropriate microsites may be required for the conservation ofnative forest systems. The rarity ofnative species in the soil seed bank and seed rain may call for such management action and the development oflong-term augmentation strategies. Alien species that form persistent soil seed banks should be a priority for eradication and control. Otherwise, ifdisturbance to native forest continues alien species with persistent soil seed banks may spring forth and possibly alter the composition ofnative vegetation. 84 CHAPTER 4: SYNTHESIS Native forests on oceanic islands throughout the world are severely reduced, fragmented, and continue to be lost at an alanning rate (Vitousek 1988; Kitayama & Mueller-Dombois 1995; Vitousek et al. 1995). Several factors have contributed to this decline, mostly related to anthropogenic alteration ofecosystems (Vitousek 1988; Kitayama & Mueller-Dombois 1995; Vitousek et al. 1995). Although the direct and indirect impacts ofhumans have greatly modified and fragmented the vegetation of Hawaiian forests (Loope & Mueller-Dombois 1989; Cuddihy & Stone 1990; Smith & Tunison 1992), native tree diversity and abundance in mesic Hawaiian forest remain relatively high. Regeneration ofnative species remains limited, though management strategies, such as ungulate exclusion and others, may address some ofthe problems. Other factors will continue to play important roles in the future composition ofthese areas. Native forest fragments are extremely important seed sources and microsites for both natural recruitment and restoration programs, but encroachment ofalien forest species and shifting edge location due to continuous disturbance and the abundance of propagules from alien species foster continuous habitat modification and fragmentation. Understanding the dynamic interaction ofdispersal agents on seed dissemination, seed rain and soil seed bank not only allows for comparisons with, and evaluations of, more general theories ofseed ecology, but also helps to guide management decisions aimed at preserving and restoring the remaining native forest ecosystems. In this study, I attempted to document how seed dispersal patterns and soil seed bank dynamics interact in and around fragmented, native forest patches in Hawaiian 85 mesic forest. As the frugivorous native avifauna has been entirely extirpated, I expected the distribution ofseeds throughout the area and the types ofseeds being dispersed to be influenced by the types ofbirds currently found at the site. To gain insights into the processes ofseed dispersal, I addressed the following hypotheses: 1) A greater density ofseed from alien species than native species are dispersed. 2) Seeds ofalien species are more likely to be dispersed into native vegetation than seeds ofnative species into alien vegetation. 3) Greater densities ofseed from alien species are dispersed into edge than into native vegetation. 4) Small seeded species are more likely to be dispersed than large seeded species. In two ofthe four cases involving seed dispersal, I support the hypotheses above (Hypothesis 1 and 2). Regarding hypothesis 1, alien species had a significantly greater density ofseed dispersed into all vegetation types than native species. In particular, birds were dispersing the majority of alien seed into all vegetation types. Excluding Clidemia hirta, the hypothesis above is not supported. Greater densities ofseed from native species were dispersed into native and edge vegetation than alien species. For hypothesis 2, I support the hypothesis above. The distributions ofdispersed seed from native and alien species were significantly different. A significantly greater density ofseed from alien species was dispersed into distant vegetation than local vegetation. In contrast, a greater density ofseed from native species was dispersed into local vegetation than distant vegetation. Many fleshy-fruited native species have large seeds probably adapted to dispersal by large-bodied birds, which are currently extinct in the Hawaiian 86 Islands. The lack ofnative species in the dispersed seed rain and in the alien vegetation, may be attributed to the fact that the majority ofdispersed native seed were large in size, and therefore limited to infrequent bird-dispersal or gravity-dispersal, both ofwhich do not facilitate the movement ofgreat numbers ofseeds far distances. For hypothesis 3, I do not support the hypothesis above. A greater density ofseed from alien species was found in native vegetation than in edge vegetation but it was not significantly different. For hypothesis 4, I do not support the hypothesis above. Significantly greater densities ofsmall seed than large seed were dispersed in all vegetation types. But, the proportion ofdispersed and not-dispersed seed from small and large seed sizes were not significantly different. The composition ofthe soil seed bank is determined by input and loss ofseeds. Seed bank input is determined by seed rain within a community. Therefore, I expected the seed banks composition and density to be influenced by the dissemination ofseeds in the vegetation types. To gain insights into the dynamics ofsoil seed banks, I addressed the following hypotheses: 5) Soil seed banks in native, edge and alien vegetation differ in composition. 6) Alien species dominate the soil seed bank in all vegetation types, in regard to species richness and density. 7) The soil seed bank in native vegetation has a greater density ofseed from native species than the soil seed bank ofalien and edge vegetation. 8) The majority ofnative species have pseudo-persistent or transient soil seed banks. 87 9) The majority ofalien species have persistent soil seed banks. 10) Species with small seeds have persistent soil seed banks. 11) Species with large seeds have transient or pseudo-persistent soil seed banks. For hypothesis 5, the above hypothesis was not supported. The composition ofthe soil seed bank in all vegetation types was similar; though densities ofa few species varied among vegetation types. A greater density ofClidemia hirta was found in the native vegetation than in the alien vegetation. A significantly greater density ofRubus rosifolius was found in edge vegetation than in other vegetation types. For hypothesis 6, I support the above hypothesis. A greater proportion ofseed from alien species (including Clidemia hirta) than native species was found in the soil seed bank in all vegetation types in regard to density and species richness. But, excluding Clidemia hirta, the densities ofnative and alien species in soil cores were not significantly different in all vegetation types. For hypothesis 7, I support the above hypothesis. Significantly greater densities of seedlings from native species were found in soil cores in native vegetation than in alien and edge vegetation. For the remaining four hypotheses 8-11, there was not enough evidence to support or reject the hypotheses. Classification ofsoil seed bank syndromes are dependent upon information regarding seed rain, seed dispersal and/or phenology for each species. Many native and large-seeded species may be present in the soil seed bank but not enough information was available in this study to conclusively classify the majority ofspecies found in the vegetation into soil seed bank syndromes. Also, soil seed bank syndromes were not classified for alien species identified in the soil seed bank but not in the extant 88 vegetation, as phenology data were not available. In other studies, these species fonned persistent soil seed banks (Drake 1998; Bossuyt et al. 2002; Peco et al. 2003). In conclusion, many ofthe trends in this study were driven by the dominance ofthe small seed and fleshy fruited alien, Clidemia hirta, which fonns a persistent soil seed bank. Despite the dominance ofClidemia hirta, current dispersal patterns indicate that a few readily disseminated non-native species are being spread throughout Kalua'a drainage. For fleshy-fruited species, the non-native frugivores may be directing the dispersal ofpredominantly non-native invasive species into all vegetation types, while the majority ofnative seeds are falling directly onto the ground without the benefits of dispersal. This pattern ofseed rain, the distribution ofnative seedlings restricted to native vegetation, and the high levels ofalien seed in the soil seed bank suggest that, without management intervention, the diverse, native forest-fragment that currently exists may eventually be replaced by a homogeneous landscape ofa few prolific invaders. The compounding effects ofalien species invasions (Loope & Mueller-Dombois 1989; Hughes et at. 1991; Smith & Tunison 1992; Medeiros et al. 1993; Kitayama & Mueller Dombois 1995), possible edge encroachment on native forest fragments, and the loss of native dispersal agents (Steadman 1995; Olson & James 1991) modifying existing seed shadows and soil seed bank composition may dramatically increase the threat of extinction to fragmented native ecosystems. Fragmented native forests may cease to exist ifimmediate threats are not addressed by removing alien species that have adaptations for bird dispersal, and/or small seeds and/or fonn persistent soil seed banks. The critical issue may then be whether extinct birds can be effectively replaced by introduced surrogates. Ifnot, the dissemination and conservation ofnative species may be 89 entirely dependent on human intervention. Management intervention requires minimal disturbance to native forests and forest remnants, otherwise, an array ofsmall-seeded alien species may spring from the forest floor altering forest composition and structure. 90 APPENDIXA. CHARACTERIZATION OF THE VEGETATION OF KALUA'A DRAINAGE STUDY SITE METHODS Plant cover in the study site was sampled at 320 points using the point-intercept method (Bonham 1989). Samples were taken at a random point in each 5-m segment of eight 200-m transects placed midway between or adjacent and parallel to, the seed dispersal transects (Chapter 2, Figure 2.2). Points recorded under two meters height were classified as ground cover, and points over two meters height were classified as canopy cover. For each species, percent cover for ground and canopy was calculated separately. At each point, a vertical line was projected and the number ofpoints, which intercepted living plant material, was counted. This value was divided by the total number of sampled points. More than one species may have been counted per point, but no single species was counted more than once per point (Table A.1- A. 13, Figure A.1-A.3). All species bounded by transects or within 50 m ofthe study area, but not encountered at any sampling point but present were noted (Table A.l4). 91 Table A.1. Abundance (Abs.= absolute abundance and %= relative cover) ofall vegetation and ground vegetation «2-m height) all three vegetation types (native, edge, alien) at Kalua'a drainage study site. All Ground Native Edge Alien Vegetation Vegetation «2-m height) «2-m «2-m height) Abs. Abs. Abs. % height) Abs. % % % Abs. % Native species Trees Acacia koa 52 4.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Antidesma platyphyllum 39 3.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Bobea elatior 1 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Claoxylon sandwicense 9 0.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Elaeocarpus bifidus 16 1.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Melicope sandwicensis 5 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Metrosideros polymorpha 48 4.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Morinda trimera 35 3.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Myrsine lessertiana 4 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Nestegis sandwicensis 2 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Pipturus albidus 11 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Pisonia brunoniana 27 2.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Pouteria sandwicensis 89 8.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Psychotria mariniana 39 3.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Psydrax odoratum 11 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Shrubs Bidens torta 14 1.3 14 2.3 12 4.6 2 2.7 0.0 0.0 Chamaesyce multiformis 1 0.1 1 0.1 1 0.4 0.0 0.0 0.0 0.0 Charpentiera obovata 2 0.2 2 0.3 2 0.8 0.0 0.0 0.0 0.0 Coprosmafiliosa 9 0.8 9 1.5 7 2.6 1 1.3 1 0.4 Cyanea angustifolia 1 0.09 1 0.1 1 0.4 0.0 0.0 0.0 0.0 92 Table A. 1. Continued. Abundance (Abs.= absolute abundance and %= relative cover) of all vegetation and ground vegetation «2-m height) all three vegetation types (native, edge, alien) at Kalua'a drainage study site. Ground Native Edge Alien All Vegetatio «2-m «2-m height) «2-m Vegetation n height) Abs. % height) Abs. % Abs. Abs. % Abs. % % Hedyotis terminalis 11 1.0 11 1.9 9 3.4 1 1.3 1 0.4 Peperomia membranacea 3 0.3 3 0.4 0.0 0.0 3 4.0 0.0 0.0 Solanum sandwicense 13 1.2 13 2.2 12 4.6 1 1.3 0.0 0.0 Urera glabra 2 0.2 2 0.3 1 0.4 1 1.3 0.0 0.0 Lianas Alyxia oliviformis 23 2.1 13 2.2 11 4.2 2 2.7 0.0 0.0 Canavalia galeata 3 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Freycinetia arborea 5 0.5 4 0.6 3 1.1 1 1.3 0.0 0.0 Smilax melastomifolia 6 0.6 6 1.0 6 2.2 0.0 0.0 0.0 0.0 Ferns Asplenium nidus 1 0.1 1 0.1 1 0.4 0.0 0.0 0.0 0.0 Cibotium chamissoi 1 0.1 1 0.1 1 0.4 0.0 0.0 0.0 0.0 Microlepia strigosa 6 0.6 6 1.0 6 2.2 0.0 0.0 0.0 0.0 Nephrolepis exaltata 10 0.9 10 1.7 10 3.8 0.0 0.0 0.0 0.0 subsp. hawaiiensis Total native species 461 45.1 97 16.7 83 34.0 12 16.6 2 0.8 Alien species Trees Aleurites moluccana 117 10.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Grevillea robusta 1 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 93 Table A. 1. Continued. Abundance (Abs.= absolute abundance and %= relative cover) of all vegetation and ground vegetation «2-m height) all three vegetation types (native, edge, alien) at Kalua'a drainage study site. All Ground Native Edge Alien Vegetati Vegetation «2-m height) «2-m «2-m on Abs. Abs. % height) height) Abs. % Abs. % Abs. % % Persea americana 1 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Psidium cattleianum 77 7.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Psidium guajava 40 3.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Schinus terebinthifolius 66 6.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Spathodea campanulata 3 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Toona ciliata 24 2.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Shrubs Clidemia hirta 82 7.7 82 13.5 29 11.2 7 9.4 46 17.0 Cordyline fruticosa 8 0.8 8 1.3 0.0 0.0 1 1.3 7 2.5 Rubus rosifolius 11 1.0 11 1.9 1 0.4 2 2.7 8 2.9 Lianas Caesalpinia major 4 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Passiflora edulis 10 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Passiflora suberosa 46 4.3 15 2.5 9 3.4 0.0 0.0 6 2.2 Graminoids Oplismenus hirtellus 64 6.0 64 10.5 0.0 0.0 4 5.4 60 22.1 Ferns Blechnum appendiculatum 7 0.7 7 1.1 3 1.1 0.0 0.0 4 1.4 Deparia petersenii 4 0.4 4 0.6 0.0 0.0 0.0 0.0 3 1.1 Total alien species 56154.8 187 32.2 42 17.2 14 19.4 131 49.4 94 Table A.1. Continued. Abundance (Abs.= absolute abundance and %= relative cover) of all vegetation and ground vegetation «2-m height) all three vegetation types (native, edge, alien) at Kalua'a drainage study site. Ground Native Edge Alien All Vegetation Vegetation «2-m «2-m «2-m Abs. % Abs. % height) height) height) Abs. % Abs. % Abs. % All species 1064 73.2 284 46.7 125 51.2 26 36.1 133 50.2 Other Litter 179 12.3 179 29.5 73 27.9 20 26.6 86 31.8 Bare Ground 118 8.1 118 19.6 46 17.6 26 34.7 46 17.0 Rock 18 1.2 18 3.0 13 5.0 2 2.7 3 1.1 Dead tree 5 0.3 5 0.8 4 1.5 1 1.3 0.0 0.0 Open sky 68 4.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Total 1453 100.0 608 100.0 262 100.0 75 100.0 271 100.0 95 Table A.2. Abundance (Abs.= absolute abundance and %= relative cover) ofcanopy vegetation (>2-m in height) in the three vegetation types (native, edge, alien) at Kalua'a drainage study site. Canopy Native Edge Alien Vegetation (>2-m height) (>2-m height) (>2-m height) Abs. % Abs. % Abs. % Abs. % Native species Trees Acacia koa 52 6.2 42 11.2 2 1.4 8 2.4 Antidesmaplatyphyllum 39 4.6 35 9.3 4 2.9 0.0 0.0 Bobea elatior 1 0.1 1 0.2 0.0 0.0 0.0 0.0 Claoxylon sandwicense 9 1.1 9 2.3 0.0 0.0 0.0 0.0 Elaeocarpus bifidus 16 1.9 11 2.9 4 2.9 1 0.3 Melicope sandwicensis 5 0.6 5 1.3 0.0 0.0 0.0 0.0 Metrosideros polymorpha 48 5.7 34 9.1 12 8.9 2 0.6 Morinda trimera 35 4.1 17 4.6 12 8.9 6 1.8 Myrsine lessertiana 4 0.5 3 0.7 1 0.7 0.0 0.0 Nestegis sandwicensis 2 0.2 1 0.1 0.0 0.0 1 0.3 Pipturus albidus 12 1.4 9 2.3 2 1.4 1 0.3 Pisonia brunoniana 27 3.1 2 0.5 14 to.3 11 3.3 Pouteria sandwicensis 89 10.6 74 19.7 8 5.9 7 2.1 Psychotria mariniana 39 4.6 23 6.2 10 7.4 6 1.8 Psydrax odoratum 11 1.3 0.0 0.0 1 0.7 10 3.0 Shrubs Bidens torta 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Chamaesyce multiformis 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Charpentiera obovata 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Coprosmajiliosa 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 96 Table A.2. Continued. Abundance (Abs.= absolute abundance and %= relative cover) of canopy vegetation (>2-m in height) in the three vegetation types (native, edge, alien) at Kalua'a drainage study site. Canopy Native Edge Alien Vegetation (>2-m height) (>2-m height) (>2-m height) Abs. % Abs. % Abs. % Abs. % Cyanea angustifolia 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Hedyotis terminalis 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Peperomia membranacea 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Solanum sandwicense 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Urera glabra 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Lianas Alyxia oliviformis 10 1.2 7 1.8 1 0.7 2 0.6 Canavalia galeata 3 0.4 2 0.5 0.0 0.0 1 0.3 Freycinetia arborea 1 0.1 0.0 0.0 1 0.7 0.0 0.0 Smilax melastomifolia 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Ferns Asplenium nidus 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Cibotium chamissoi 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Microlepia strigosa 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Nephrolepis exaltata subsp. hawaiiensis 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Total native species 364 45.2 240 70.1 68 51.5 56 16.9 Alien species 97 Table A.2. Continued. Abundance (Abs.= absolute abundance and %= relative cover) of canopy vegetation (>2-m in height) in the three vegetation types (native, edge, alien) at Kalua'a drainage study site. Canopy Native Edge Alien Vegetation (>2-m height) (>2-m height) (>2-m Abs. % Abs. % Abs. % height) Abs. % Trees Aleurites moluccana 117 13.9 14 3.7 32 23.5 71 21.4 Grevillea robusta 1 0.1 0.0 0.0 0.0 0.0 1 0.3 Persea americana 1 0.1 0.0 0.0 0.0 0.0 1 0.3 Psidium cattleianum 77 9.2 2 0.5 13 9.5 62 18.7 Psidium guajava 40 4.7 0.0 0.0 2 1.4 38 11.4 Schinus terebinthifolius 66 7.9 14 3.7 6 4.4 46 13.9 Toona ciliata 24 2.8 0.0 0.0 8 5.9 16 4.8 Shrubs Clidemia hirta 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Cordyline fruticosa 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Rubus rosifolius 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Lianas Caesalpinia major 4 0.5 0.0 0.0 1 0.7 3 0.2 Passiflora edulis 10 1.1 10 2.6 0.0 0.0 0.0 0.0 Passiflora suberosa 21 3.6 17 4.6 1 0.7 13 3.9 Graminoids Oplismenus hirtellus 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Ferns Blechnum appendiculatum 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 98 Table A.2. Continued. Abundance (Abs.= absolute abundance and %= relative cover) of canopy vegetation (>2-m in height) in the three vegetation types (native, edge, alien) at Kalua'a drainage study site. Canopy Native Edge Alien Vegetation (>2-m (>2-m (>2-m height) Abs. % height) height) Abs. % Abs. % Abs. % Deparia petersenii 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Total alien species 374 46.4 57 16.7 63 47.7 254 76.5 All species 738 87.3 297 86.6 131 99.2 310 93.4 Other Litter 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Bare Ground 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Rock 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Dead tree 0.0 0.0 0.0 0,0 0.0 0.0 0.0 0.0 Open sky 68 8.1 45 13.2 1 0.8 22 6.6 Total 845 100.0 377 100.0 136 100.0 332 100.0 99 Table A.3. Plant species present with the entire study area bounded by transects at Kalua'a drainage. Species Name Common Name Family Name Form Status Acacia koa Koa Fabaceae Tree Native Aleurites moluccana Kukui Euphorbiaceae Tree Alien Alyxia oliviformis Maile Apocynaceae Woody vine Native Antidesmaplatyphyllum Hame Euphorbiaceae Tree Native Asplenium nidus 'Ekaha Aspleniaceae Fern Native Bidens pi/osa Beggar's tick Asteraceae Shrub Alien Bidens torta Ko'oko'olau Asteraceae Shrub Native Blechnum appendiculatum None Blechnaceae Fern Alien Bobea elatior 'Ahakea Rubiaceae Tree Native Caesalpinia major Yellow knickers Fabaceae Woody vine Alien Canavalia galeata 'Awikiwiki Fabaceae Woody vine Native Carex wahuensis None Cyperaceae Sedge Native Chamaesyce multiformis 'Akoko Euphorbiaceae Shrub Native Charpentiera obovata Papala Amaranthaceae Tree Native Cibotium chamissoi Hapu'u Dicksoniaceae Fern Native Claoxylon sandwicense Po'ola nui Euphorbiaceae Tree Native Clidemia hirta Coster's curse Melastomataceae Shrub Alien Cordyline fruticosa Ki Agavaceae Shrub Alien Coprosma filiosa Pilo Rubiaceae Shrub Native Cyanea angustifolia Haha Campanulaceae Shrub Native Cyanea grimesiana Haha Campanulaceae Shrub Native Cyanea pinnatifida Haha Campanulaceae Shrub Native Delissa subcordata None Campanulaceae Shrub Native Deparia petersenii None Athyriaceae Fern Alien 100 Table A.3. Continued.Plant species present with the entire study area bounded by transects at Kalua'a drainage. Species Name Common Name Family Name Form Status Dianella sandwicensis 'Uki'uki Liliaceae Shrub Native Diospyros hillebrandii Lama Ebenaceae Tree Native Diospyros sandwicensis Lama Ebenaceae Tree Native Elaeocarpusbij7dus Kalia Elaeocarpaceae Tree Native Eucalyptus robusta Swamp mahogany Myrtaceae Tree Alien Fraxinus uhdei Tropical ash Oleaceae Tree Alien Freycinetia arborea 'Ie'ie Pandanaceae Woody vine Native Grevillea robusta Silk oak Proteaceae Tree Alien Hedyotis terminalis Manono Rubiaceae Shrub Native Lantana camara None Verbenaceae Shrub Alien Melicope sandwicensis Alani Rutaceae Tree Native Metrosideros polymorpha 'Ohi'a lehua Myrtaceae Tree Native Microlepia strigosa Palapalai Dennstaedtiaceae Fern Native Morinda trimera Noni kuahiwi Rubiaceae Tree Native Myrsine lessertiana Kolea Myrsinaceae Tree Native Nephrolepis exaltata subsp. hawaiiensis 'Okupukupu Nephrolepidaceae Fern Native Nestegis sandwicensis Olopua Oleaceae Tree Native Oplismenus hirtellus Basket grass Poaceae Grass Alien Oxalis corniculata Yellow wood sorrel Oxalidaceae Shrub Alien Passiflora edulis Lilikoi Passifloraceae Vine Alien Passiflora suberosa Corky passion vine Passifloraceae Vine Alien Peperomia membranacea 'Ala'alawainui Piperaceae Shrub Native Persea Americana Avocado Lauraceae Tree Alien Phyllostegia mollis None Lamiaceae Shrub Native 101 Table A.3. Continued.Plant species present with the entire study area bounded by transects at Kalua'a drainage. Species Name Common Name Family Name Form Status Pipturus albidus Mamaki Urticaeae Tree Native Pisonia brunoniana Papala kepau Nyctaginaceae Tree Native Platydesma cornuta Pilo kea Rutaceae Tree Native Pouteria sandwicensis ,Ala'a Sapotaceae Tree Native Psidium cattleianum Strawberry guava Myrtaceae Tree Alien Psidium guajava Common guava Myrtaceae Tree Alien Psychotria hathewayi Kopiko Rubiaceae Tree Native Psychotria mariniana Kopiko Rubiaceae Tree Native Psydrax odoratum Alahe'e Rubiaceae Tree Native Rauvolfia sandwicensis Hao Apocynaceae Tree Native Rubus rosifolius Thimbleberry Rosaceae Shrub Alien Rumex albescens Pawale Polygonaceae Shrub Native Schiedea kaalae None Caryophyllaceae Shrub Native . Schiedea pubescens None Caryophyllaceae Shrub Native Schinus terebinthifolius Christmas berry Anacardiaceae Tree Alien Smilax melastomifolia None Smilacaeae Woody vine Native Solanum sandwicense Popolo Solanaceae Shrub Native Spathodea campanulata African tulip Bignoniaceae Tree Alien Strebulus pendulinus A'ia'i Moraceae Tree Native Toona ciliata Australian red cedar Meliaceae Tree Alien Urera glabra Opuhe Urticaceae Shrub Native Urera kaalae Opuhe Urticaceae Shrub Native 102 OPEN 13% ALIEN 17% Figure A.1. Relative percent cover ofcanopy tree species and open sky in the native forest community at Kalua'a drainage. Alien = alien tree species; Native = native tree species; Open = open sky. OPEN NATIVE 7% 17% ALIEN 76% Figure A.2. Relative percent cover ofcanopy tree species and open sky in the alien forest community at Kalua'a drainage. Alien = alien tree species; Native = native tree species; Open = open sky. 103 OPEN 1% ALIEN NATIVE 48% 51% Figure A.3. Relative percent cover ofcanopy tree species and open sky in the edge forest community at Kalua'a drainage. Alien = alien tree species; Native = native tree species; Open = open sky. 104 APPENDIX B. PHENOLOGY OF THE VEGETATION OF KALUA'A DRAINAGE STUDY SITE METHODS The presence ofimmature and ripe fruits on species in the study area was recorded on a monthly basis from June 2003 to May 2004 to document the potential pool ofseeds that could be disseminated in the area. For all mature reproductive species in or within 50 m ofthe study area, 5 to 15 reproductive individuals (female, ifdioecious species) per species were randomly selected. Most ofthese individuals occurred along seed sampling transects or trails within or near the study area. For each sampled individual, percentages ofstems with immature and ripe fruit were estimated and recorded in categories (0 = none; 1 = 1-20 percent; 2 = 21-40 percent; 3 = 41-60 percent; 4 = 61-80 percent; 5 = 81-100 percent). Means for individuals were calculated using the following values for each phenology category: 0 = 0; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent (Tables B.1-B.13; Figures B.1-B.1O). 105 Table B.l. Monthly percentage ofnative species with mature fruit. Aca koa: Acacia koa (n = 15); Ant pia: Antidesma platyphyllum (n = 15); Ela bif: Elaeocarpus bifidus (n = 10); Bob ela: Bobea elatior(n = 2); Pis bru: Pisonia brunoniana (n = 15); Psy mar: Psychotria mariniana (n = 15); Met pol: Metrosideros polymorpha (n = 15); Mor tri: Morinda trimera (n = 5); Pip alb: Pipturus albidus (n = 15); Psy ord: Psydrax odoratum (n = 10); Pou san: Pouteria sandwicensis (n = 15); Aly oli: Alyxia oliviformis (n = 10); Bid tor: Bidens torta (n = 15); Can gal: Canavalia galeata (n = 5); Cha obo: Charpentiera obovata (n = 10). Aca koa A~t Ela bif Bob ela Pis bru Psy mar Met pol ~~r Pip alb Psy ord Pou Aly Bid Can Date pan san oli tor gaI Chaobo Jun-03 0.3 0.0 0.0 1.0 0.2 0.5 0.0 0.0 0.5 0.0 0.8 0.8 0.5 0.0 0.0 Jul-03 0.5 0.0 0.0 1.0 0.0 0.2 0.0 0.0 0.3 0.0 1.0 1.0 0.8 0.0 0.0 Aug-03 1.0 0.0 0.0 0.5 0.0 0.2 0.3 0.2 0.0 0.0 1.0 1.0 1.0 0.4 0.0 1.0 0.0 0.0 0.5 0.0 0.5 0.4 0.6 0.0 0.0 0.6 0.8 1.0 1.0 0.0 ...... Sep-03 0 Oct-03 1.0 0.0 0.0 0.0 0.0 0.8 1.0 1.0 0.0 0.0 0.3 0.4 0.5 1.0 0.0 0'1 Nov-03 0.8 0.2 0.0 0.0 0.0 1.0 0.5 1.0 0.0 0.0 1.0 0.4 0.3 0.8 0.6 Dec-03 0.3 0.3 0.0 0.0 0.0 1.0 0.4 0.6 0.0 0.0 0.9 0.1 0.2 0.6 0.8 Jan-04 0.3 0.7 0.2 0.0 0.2 0.7 0.3 0.4 0.0 0.0 0.2 0.1 0.2 0.2 0.5 Feb-04 0.2 0.5 0.6 0.0 0.5 0.2 0.3 0.4 0.0 0.2 0.9 0.6 0.0 0.0 0.4 Mar-04 1.0 0.5 1.0 0.0 1.0 0.8 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.0 0.2 Apr-04 1.0 0.4 1.0 0.0 1.0 0.9 0.0 0.2 0.5 0.8 0.9 1.0 0.5 0.0 0.2 May-04 1.0 0.3 1.0 0.0 1.0 1.0 0.0 0.4 1.0 1.0 1.0 0.8 1.0 0.2 0.3 Jun-04 1.0 0.0 0.6 1.0 0.8 0.6 0.0 0.8 0.8 0.7 1.0 1.0 1.0 1.0 0.6 Table B.2. Monthly percentage ofalien species with mature fruit. Ale mol: Aleurites rnoluccana (n = 15); Gre rob: Grevillea robusta (n = 5); Psi cat: Psidiurn cattleianurn (n = 15); Psi gua: Psidiurn guqjava (n = 15); Spa earn: Spathodea campanulata (n = 5); Sch ter: Schinus terebinthifolius (n = 15); Too cit: Toona ciliata (n = 5); Cae maj: Caesalpinia major (n=??); Cli hir: Clidemia hirta (n = 15); Lan earn: Lantana camara (n = 5); Opl hir: Oplismenus hirtellus (n = 15); Oxa cor: Oxalis corniculata (n = 15); Pas sub: Passiflora suberosa (n = 15); Pas edu: Passiflora edulis (n = 5); Rub ros: Rubus rosifolius (n = 5). Gre P.P. Spa Date Ale mol SI cat 81 gua Sch ter Too cit Ca: Cli hir Lan 0 I hir Oxa Pas sub Pas Rub ros rob earn maJ earn p cor edu Jun-03 0.5 0.4 0.8 0.0 0.6 0.3 1.0 0.2 1.0 0.2 0.0 0.2 1.0 0.8 1.0 Jul-03 1.0 0.0 0.9 0.3 0.6 0.3 1.0 0.0 1.0 0.0 0.0 0.2 0.9 0.8 1.0 Aug-03 1.0 0.0 1.0 0.8 0.8 0.8 1.0 0.0 1.0 0.0 0.0 0.0 0.9 0.6 0.9 Sep-03 1.0 0.0 0.5 1.0 1.0 1.0 0.6 0.2 0.7 0.0 0.0 0.0 1.0 0.2 0.8 Oct-03 0.8 0.0 0.3 1.0 0.8 0.9 0.4 0.6 0.8 0.0 0.0 0.0 1.0 0.0 0.8 Nov-03 0.8 0.0 0.2 0.5 0.4 0.6 0.4 0.8 0.9 0.0 0.0 0.0 1.0 0.0 0.6 ...... Dec-03 1.0 0.0 0.2 0.3 0.4 0.4 0.0 0.6 1.0 0.2 0.5 0.0 1.0 0.4 0.6 0 -....:l Jan-04 1.0 0.0 0.0 0.2 0.0 0.3 0.0 0.4 1.0 0.6 1.0 0.2 0.9 0.8 0.9 Feb-04 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.6 1.0 0.4 0.9 1.0 1.0 Mar-04 0.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Apr-04 0.8 0.2 0.0 0.0 0.0 0.0 0.0 0.6 1.0 0.9 1.0 1.0 0.9 0.8 0.7 May-04 0.8 0.8 0.3 0.2 0.0 0.0 0.0 0.8 1.0 1.0 0.9 0.4 0.9 0.4 0.6 Jun-04 0.8 0.8 0.4 1.0 0.4 0.0 0.0 0.8 0.8 0.7 0.8 0.4 0.9 0.2 0.8 Table B.3. Mean (± 1 SE) monthly percentage ofstems with immature fruits by native species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent). Aca koa: Acacia koa (n = 15); Ant pIa: Antidesmaplatyphyllum (n = 15); Eia bif: Elaeocarpus bifidus (n = 10); Bob eIa: Bobea elatior (n = 2); Pis bru: Pisonia brunoniana (n = 15); Psy mar: Psychotria mariniana (n = 15); Met pol: Metrosideros polymorpha (n = 15); Mor tri: Morinda trimera (n = 5). Date Acakoa Ant pIa Ela bif Bob ela Pis bru Mortri Met pol Psy mar Jun-03 70.5 (8.2) 0.0 (0.0) 0.0 10.5 0.0 0.0 37.8 (12.6) (0.0) (0.0) (0.0) (0.0) 0.0 (0.0) Jul-03 75.5 (9.6) 0.0 (0.0) 0.0 10.5 2.6 2.6 50.5 (11.5) (5.2) (2.6) (0.0) (0.0) 0.0 (0.0) Aug-03 2.5 (2.6) 0.0 (0.0) 0.0 15.5 7.8 10.5 40.5 (10.0) (0.0) (2.6) (5.0) (0.0) 0.0 (0.0) Sep-03 0.0 (0.0) 0.0 (0.0) 0.0 7.8 40.5 40.5 12.6 (12.6) (11.5) (12.9) (2.6) (0.0) 0.0 (0.0) Oct-03 5.2 (3.0) 5.2 (3.0) 0.0 5.2 35.5 25.5 30.5 (8.2) (19.2) (9.8) (3.0) (0.0) 0.0 (0.0) Nov-03 45.5 (12.6) 30.5 (8.2) 2.6 2.6 15.5 7.6 25.5 (5.0) (15.3) (5.0) (2.6) (2.6) 0.0 (0.0) Dec-03 10.2 (7.2) 45.5 (5.0) 10.5 2.6 2.6 2.6 17.8 (11.2) (5.3) (2.6) (2.6) (0.0) 0.0 (0.0) .-. Jan-04 12.8 (6.4) 40.5 (5.8) 30.5 2.6 0.0 0.0 12.8 (6.4) (0.0) (0.0) (2.6) (8.2) 0.0 (0.0) 0 00 Feb-04 10.5 (0.0) 7.8 (2.6) 35.5 0.0 0.0 10.5 7.6 (7.63) (0.0) (0.0) (0.0) (9.6) 0.0 (0.0) Mar-04 0.0 (0.0) 2.6 (0.0) 22.8 2.6 0.0 45.5 30.5 (8.2) (10.0) (0.0) (2.6) (11.2) 0.0 (0.0) Apr-04 0.0 (0.0) 0.0 (0.0) 10.2 12.8 0.0 55.5 50.5 (8.2) (19.5) (0.0) (6.4) (7.2) 2.7 (2.6) May-04 5.2 (3.0) 0.0 (0.0) 2.6 15.5 7.6 30.5 30.5 (8.2) (16.3) (7.6) (5.0) (2.6) 15.3 (8.8) Jun-04 17.8 (7.6) 0.0 (0.0) 0.0 10.5 15.5 10.2 20.3 (12.4) (14.4) (5.0) (0.0) (0.0) 25.3 (14.5) Table B.3. Continued. Mean (± 1 SE) monthly percentage ofstems with immature fruits by native species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent). Pip alb: Pipturus albidus (n = 15); Psy ord: Psydrax odoratum (n = 10); Aly oli: Alyxia oliviformis (n = 10); Bid tor: Bidens torta (n = 15); Can gal: Canavalia galeata (n = 5); Cha obo: Charpentiera obovata (n = 10). Date Pou san Pip alb Psy ord Aly oli Bid tor Can gal Chaobo Jun-03 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 5.2 (3.0) 2.6 (2.6) 0.0 (0.0) 0.0 (0.0) Jul-03 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 12.8 (6.4) 15.5 (5.0) 30.5 (8.1) 0.0 (0.0) Aug-03 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 10.2 (7.2) 45.5 (12.6) 40.5 (8.4) 0.0 (0.0) Sep-03 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 2.6 (2.6) 15.2 (12.0) 20.2 (10.3) 2.6 (2.6) Oct-03 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 7.6 (7.6) 7.6 (6.1) 5.2 (3.0) Nov-03 2.6 (2.6) 0.0 (0.0) 0.0 (0.0) 5.2 (3.0) 0.0 (0.0) 0.0 (0.0) 10.5 (0.0) Dec-03 5.5 (3.0) 0.0 (0.0) 2.6 (2.6) 20.5 (l0.0) 0.0 (0.0) 0.0 (0.0) 15.2 (12.0) ..... 0 Jan-04 16.7 (5.0) 2.6 (2.6) 47.8 (24.7) 75.5 (9.6) 0.0 (0.0) 0.0 (0.0) 2.6 (2.6) ID Feb-04 36.7 (5.0) 2.6 (3.0) 85.5 (5.0) 75.5 (5.0) 2.6 (2.6) 7.5 (6.1) 2.6 (2.6) Mar-04 56.7 (9.8) 18.3 (9.6) 55.5 (5.0) 45.5 (5.0) 18.0 (7.5) 25.5 (8.5) 17.8 (7.6) Apr-04 46.2 (9.8) 28.8 (8.2) 17.8 (7.6) 20.5 (5.8) 50.5 (14.1) 35.5 (9.6) 35.5 (5.0) May-04 12.8 (6.4) 48.6 (18.3) 0.0 (0.0) 10.5 (0.0) 75.5 (9.6) 45.5 (8.9) 17.8 (7.6) Jun-04 2.6 (0.0) 43.6 (20.6) 0.0 (0.0) 25.5 (9.8) 50.5 (11.5) 40.5 (10.6) 7.6 (7.6) Table B.4. Mean (± 1 SE) monthly percentage ofstems with immature fruits ofalien species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent). Ale mol: Aleurites moluccana (n = 15); Gre rob: Grevillea robusta (n = 5); Psi cat: Psidium cattleianum (n = 15); Psi gua: Psidium guajava (n = 15); Spa carn: Spathodea campanulata (n = 5); Sch ter: Schinus terebinthifolius (n = 15); Too cil: Toona ciliata (n = 5); Cae maj: Caesalpinia major (n=??); Cli hir: Clidemia hirta (n = 15); Lan carn: Lantana camara (n = 5); Opl hir: Oplismenus hirtellus (n = 15); Oxa cor: Oxalis corniculata (n = 15); Pas sub: Passiflora suberosa(n = 15); Pas edu: Passiflora edulis (n = 5); Rub ros: Rubus rosifolius (n = 5). Gre Date Ale mol P.P.SI cat SI gua Spa Sc hter T00 Cl'1 Cae. cr1 hirLan 0 p1hi r Oxa Pas su b Pasd Rubros rob carn rna] carn cor e u Joo-03 45.5 0.0 25.5 80.5 17.6 80.5 12.8 2.6 20.5 0.0 0.0 0.0 50.5 0.0 25.5 (9.3) (0.0) (9.6) (5.8) (17.6) (5.8) (5.7) (2.6) (5.7) (0.0) (0.0) (0.0) (14.1) (0.0) (9.6) Jul-03 50.5 0.0 5.2 60.5 52.8 65.5 2.6 0.0 35.5 0.0 0.0 0.0 65.5 0.0 20.5 (14.1) (0.0) (3.0) (5.8) (19.4) (5.0) (2.6) (0.0) (5.0) (0.0) (0.0) (0.0) (9.6) (0.0) (10.0) ...... Aug-03 50.5 0.0 0.0 35.5 0.0 12.8 0.0 0.0 45.5 0.0 0.0 0.0 55.5 0.0 15.5 ...... 0 (14.1) (0.0) (0.0) (9.6) (0.0) (6.4) (0.0) (0.0) (5.0) (0.0) (0.0) (0.0) (5.0) (0.0) (5.0) Sep-03 45.5 0.0 0.0 10.5 0.0 0.0 0.0 2.6 55.5 0.0 0.0 0.0 45.5 0.0 10.5 (9.8) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (2.1) (9.6) (0.0) (0.0) (0.0) (5.0) (0.0) (0.0) Oct-03 40.5 0.0 0.0 2.6 0.0 0.0 0.0 10.2 30.5 0.0 0.0 10.2 65.5 0.0 12.8 (5.8) (0.0) (0.0) (2.6) (0.0) (0.0) (0.0) (7.1) (8.2) (0.0) (0.0) (7.2) (9.6) (0.0) (6.4) Nov-03 30.5 0.0 0.0 0.0 0.0 0.0 0.0 12.8 25.5 2.6 30.5 17.8 50.5 10.9 52 (30) (8.2) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (6.3) (9.6) (2.6) (8.2) (7.6) (14.1) (5.6) .. Dec-03 0.0 13.0 70.5 32.8 55.5 35.4 20.5 30.5 0.0 0.0 0.0 0.0 0.0 5.2 20.5 (0.0) (0.0) (0.0) (3.0) (6.3) (8.2) (11.9) (5.0) (7.5) (5.7) (8.2) (0.0) (0.0) (0.0) (5.7) Jan-04 27.8 0.0 0.0 0.0 0.0 0.0 0.0 2.6 10.5 40.5 90.5 17.8 45.5 43.4 30.5 (10.4) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (2.6) (0.0) (5.8) (3.5) (7.6) (5.0) (4.9) (1.2) Feb-04 27.8 15.2 7.6 2.6 0.0 0.0 0.0 0.0 20.5 60.5 70.5 102 65.5 16.4 20.5 (10.4) (12.0) (7.6) (2.6) (0.0) (0.0) (0.0) (0.0) (5.7) (5.8) (8.4) 97.2) (9.6) (10.4) (10.0) Mar-04 30.5 45.5 30.5 37.8 0.0 0.0 0.0 0.0 30.5 75.5 32.8 2.6 50.5 2.1 17.8 (8.2) (17.1) (8.2) (15.0) (0.0) (0.0) (0.0) .(0.0) (0.0) (9.8) (U.9) (2.6) (14.1) (1.9L (7.6) Table BA. Continued. Mean (± 1 SE) monthly percentage ofstems with immature fruits ofalien species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent). Ale mol: Aleurites moluccana (n = 15); Gre rob: Grevillea robusta (n = 5); Psi cat: Psidium cattleianum (n = 15); Psi gua: Psidium guajava (n = 15); Spa cam: Spathodea campanulata (n = 5); Sch ter: Schinus terebinthifolius (n = 15); Too ci1: Toona ciliata (n = 5); Cae maj: Caesalpinia major (n=??); Cli hir: Clidemia hirta (n = 15); Lan cam: Lantana camara (n = 5); Opl hir: Oplismenus hirtellus (n = 15); Oxa cor: Oxalis corniculata (n = 15); Pas sub: Passiflora suberosa (n = 15); Pas edu: Passiflora edulis (n = 5); Rub ros: Rubus rosifolius (n = 5). Date Ale mol Greb p'SI cat P.SI gua Spa Sc hter T00 Cl'1 Cae. cr1 hirLan 0 p1h'lr Oxa Pas su b Pasd Rub ros ro cam rna] cam cor e u Apr-04 30.5 75.5 85.5 70.5 12.6 7.62 2.6 7.8 40.5 65.5 2.6 2.6 65.5 (i:~) (8.2) (9.8) (5.0) (8.2) (12.6) (7.6) (2.6) (2.6) (5.0) (9.8) (2.6) (2.6) (9.6) 5.2 (3.0) May-04 30.5 50.5 70.5 75.5 17.6 15.2 15.2 17.8 55.5 22.8 0.0 2.6 50.5 0.0 12.8 (8.2) (11.6) (8.2) (9.6) (17.6) (8.8) (12.0) (7.6) (9.8) (11.2) (0.0) (2.6) (11.4) (0.0) (6.4) Jun-04 40.5 17.8 35.2 35.5 52.8 65.5 90.5 5.2 45.5 10.2 0.0 2.6 65.5 0.0 20.5 - (5.8) (7.6) (5.1) (5.0) (19.4) (9.6)(11.6) (3.1)_(5.7) (7.2) jO.9) (2.6) (9.3) (0.0) (10.0) Table B.S. Mean (± 1 SE) monthly percentage ofstems with mature fruits by native species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent). Aca koa: Acacia koa (n = 15); Ant pIa: Antidesmaplatyphyllum (n = 15); Ela bif: Elaeocarpus bifidus (n = 10); Bob ela: Bobea elatior (n = 2); Pis bru: Pisonia brunoniana (n = 15); Psy mar: Psychotria mariniana (n = 15); Met pol: Metrosideros polymorpha (n = 15); Mor tri: Morinda trimera (n = 5). Date Acakoa Ant pIa Ela bif Bob ela Pis bru Psymar Jun-03 5.2 (3.0) 0.0 (0.0) 0.0 (0.0) 30.2 (17.9) 2.6 (0.3) 7.8 (5.2) Jul-03 25.5 (9.6) 0.0 (0.0) 0.0 (0.0) 10.5 (7.2) 0.0 (0.0) 2.5 (1.3) Aug-03 75.5 (9.2) 0.0 (0.0) 0.0 (0.0) 7.6 (7.6) 0.0 (0.0) 2.6 (2.3) Sep-03 80.5 (10.1) 0.0 (0.0) 0.0 (0.0) 2.6 (1.6) 0.0 (0.0) 7.8 (5.3) ...... Oct-03 75.5 (9.6) 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 35.5 (5.5) ...... N Nov-03 40.5 (12.9) 2.6 (0.0) 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 45.5 (10.0) Dec-03 30.5 (14.1) 5.2 (2.6) 0.0 (0.0) 0.0 (0.0) 0.0 (0.0) 20.5 (10.2) Jan-04 5.2 (3.0) 25.5 (3.1) 2.6 (2.5) 0.0 (0.0) 2.6 (2.4) 12.8 (11.6) Feb-04 2.6 (2.6) 45.5 (5.1) 7.5 (2.4) 0.0 (0.0) 18.3 (7.6) 2.6 (2.1) Mar-04 7.8 (2.6) 22.8 (5.0) 20.5 (5.8) 0.0 (0.0) 26.7 (5.2) 7.8 (7.4) Apr-04 25.5 (5.1) 7.8 (1.1) 45.5 (5.0) 0.0 (0.0) 51.7 (8.2) 25.5 (5.2) May-04 50.5 (8.1) 2.6 (2.6) 40.5 (5.6) 0.0 (0.0) 51.7(3.2) 55.5 (10.3) Jun-04 60.5 (12.8) 0.0 (0.0) 22.5 (7.6) J_~{3.1) 26.5 (5.0) 55.5 (9.8) Table B.S. Continued. Mean (± 1 SE) monthly percentage ofstems with mature fruits by native tree species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent). Psy mar: Psychotria mariniana (n = 15); Met pol: Metrosideros polymorpha (n = 15); Mor tri: Morinda trimera (n = 5). Pip alb: Pipturus albidus (n = 15); Psy ord: Psydrax odoratum (n = 10); Pou san: Pouteria sandwicensis (n = 15); Aly oli: Alyxia oliviformis (n = 10); Bid tor: Bidens torta (n = 15); Can gal: Canavalia galeata (n = 5); Cha obo: Charpentiera obovata (n = 10). Date Met pol Mortri Pip alb Psy ord Pousan Aly oli Bid tor Can gal Chaobo Jun-03 10.2 (7.2) 2.6 (2.6) 0.0 (0.0) 0.0 (0.0) 50.5 (11.5) 75.5 (5.0) 7.8 (2.4) 17.8 (6.7) 0.0 (0.0) JuI-03 15.2 (8.8) 12.8 (6.3) 0.0 (0.0) 0.0 (0.0) 27.8 (lOA) 65.5 (15.0) 10.5 (1.2) 10.2 (5.9) 0.0 (0.0) Aug-03 33.0 (6.3) 20.5 (5.7) 0.0 (0.0) 0.0 (0.0) 20.2 (12.4) 80.5 (5.8) 20.5 (5.7) 0.0 (0.0) 0.0 (0.0) Sep-03 50.5 (8.1) 15.5 (5.0) 0.0 (0.0) 0.0 (0.0) 35.5 (9.6) 70.5 (3.9) 30.5 (0.3) 10.5 (1.1) 0.0 (0.0) Oct-03 20.2 (12.4) 2.6 (2.3) 0.0 (0.0) 0.0 (0.0) 15.5 (6.1) 20.2 (12.4) 40.5 (12.9) 20.5 (5.4) 0.0 (0.0) Nov-03 7.6 (7.7) 2.6 (2.6) 0.0 (0.0) 0.0 (0.0) 12.6 (12.6) 5.25 (3.1) 20.2 (12.4) 5.3 (2.6) 12.8 (6.3) -w Dec-03 2.6 (2.6) 2.6 (2.1) 0.0 (0.0) 2.6 (2.6) 30.5 (3.0) 2.6 (2.3) 7.6 (7.6) 17.9 (6.6) 25.5 (5.0) Jan-04 0.0 (0.0) 2.6 (2.6) 7.6 (7.5) 45.5 (12.6) 40.5 (5.8) 2.6 (2.6) 2.6 (1.2) 5.2(2.8) 17.8(7.6) Feb-04 0.0 (0.0) 2.6 (2.6) 15.2 (8.8) 70.5 (1.2) 50.5 (2.3) 22.8 (11.2) 0.0 (0.0) 0.0 (0.0) 10.2 (7.9) Mar-04 0.0 (0.0) 5.2 (3.1) 38.1 (12.9) 80.5 (8.1) 50.5 (8.2) 25.5 (9.6) 0.0 (0.0) 0.0 (0.0) 7.6 (2.6) Apr-04 0.0 (0.0) 15.5 (5.0) 48.6 (14.1) 45.5 (5.1) 55.5 (5.1) 55.5 (9.5) 7.8 (2.6) 0.0 (0.0) 2.6 (2.3) May-04 10.2 (7.2) 2.6 (2.6) 0.0 (0.0) 0.0 (0.0) 50.5 (11.5) 60.5 (12.9) 10.5 (1.3) 5.3 (2.5) 2.6 (1.2) Jun-04 15.2 (8.8) 12.8 (6.3) 0.0 (0.0) 0.0 (0.0) 27.8 (10.4) 70.5 (8.0) 30.5i~J) 20.5 (5.4) 17.8 (7.6) Table B.6. Mean (± 1 SE) monthly percentage ofstems with mature fruits ofalien species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent). Ale mol: Aleurites moluccana (n = 15);Gre rob: Grevillea robusta (n = 5); Psi cat: Psidium cattleianum (n = 15); Psi gua: Psidium guajava (n = 15); Spa cam: Spathodea campanulata (n = 5); Sch ter: Schinus terebinthifolius (n = 15); Too cil: Toona ciliata (n = 5); Cae maj: Caesalpinia major (n=??); Cli hir: Clidemia hirta (n = 15); Lan cam: Lantana camara (n = 5); Opl hir: Oplismenus hirtellus (n = 15); Oxa cor: Oxalis corniculata (n = 15); Pas sub: Passiflora suberosa (n = 15); Pas edu: Passiflora edulis (n = 5); Rub ros: Rubus rosifolius (n = 5). Cae Lan . Oxa Date Al~ Gre rob Psi cat Psi gua Spa Sch ter Too cil Cli hir Opl hir Pas subPas eduRub ros mo cam rna] cam cor Jun-03 27.8 5.2 85.5 0.0 2.6 5.2 90.5 10.2 20.5 7.6 0.0 2.6 65.5 29.2 30.5 (10.4) (3.0) (3.1) (0.0) (1.6) (3.1) (2.1) (7.2) (1.2) (7.1) (0.0) (2.1) (9.5) (10.3) (1.4) Jul-03 30.5 0.0 85.5 10.2 12.6 10.2 90.5 7.6 10.5 0.0 0.0 2.6 50.5 21.2 25.5 (8.2) (0.0) (9.5) (7.2) (12.1) (7.1) (1.2) (7.6) (5.7) (0.0) (0.0) (1.9) (9.7) (9.0) (10.0) Aug-03 30.5 0.0 60.5 55.5 30.2 50.5 80.5 7.6 20.5 0.0 0.0 0.0 50.5 10.9 20.5 ...... (8.1) (0.0) (9.8) (17.1) (17.9) (8.2) (5.7) (7.4) (5.2) (0.0) (0.0) (0.0) (14.1) (5.5) (9.6) ..j::. Sep-03 40.5 0.0 32.8 80.5 52.8 75.5 42.8 2.6 20.5 0.0 0.0 0.0 65.5 2.3 15.5 (5.6) (0.0) (10.1) (5.8) (22.3) (5.0) (15.0) (2.6) (5.0) (0.0) (0.0) (0.0) (13.9) (2.1) (10.2) Oct-03 45.5 0.0 10.2 75.5 20.2 55.5 25.2 0.0 35.5 0.0 0.0 0.0 55.5 0.0 10.5 (9.6) (0.0) (9.3) (9.8) (12.4) (15.0) (3.0) (0.0) (4.9) (0.0) (0.0) (0.0) (8~5) (0.0) (5.1) Nov-03 50.5 0.0 2.6 22.8 2.6 20.2 5.2 0.0 45.5 0.0 0.0 0.0 45.5 0.0 12.8 (14.1) (0.0) (2.1) (11.2) (2.1) (12.4) (1.2) (0.0) (9.6) (0.0) (0.0) (0.0) (5.0) (0.0) (6.3) Dec-03 50.5 0.0 2.6 10.2 2.6 7.6 0.0 7.6 55.5 2.6 7.8 0.0 45.5 4.6 12.8 (12.2) (0.0) (2.3) (7.2) (2.6) (7.1) (0.0) (7.6) (8.1) (2.3) (7.6) (0.0) (5.1) (2.5) (6.7) Jan-04 45.5 0.0 0.0 7.6 0.0 2.6 0.0 17.8 30.5 10.3 30.5 2.6 65.5 25.2 25.5 (9.7) (0.0) (0.0) (7.3) (0.0) (2.0) (0.0) (7.5) (9.5) (10.2) (8.1) (2.1) (5.3) (8.8) (9.4) Feb-04 45.5 0.0 0.0 0.0 0.0 0.0 0.0 7.8 25.5 22.8 70.5 10.2 50.5 43.5 20.5 (9.3) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (2.6) (5.0) (7.1) (7.8) (7.1) (8.9) (4.9) (9.9) Mar-04 40.5 0.0 0.0 0.0 0.0 0.0 0.0 10.2 55.5 50.5 90.5 27.8 65.5 39.5 30.5 (5.6) (0.01 (0.0) (0.0) (0.0) (0.0) (0.0) (7.1) (9.4) (7.6) .. G.l) (13.2) (1O.0)H.~) (2·1) ------... _-_._ ...... _--- - ._._------Table B.6. Continued. Mean (± 1 SE) monthly percentage ofstems with mature fruits ofalien species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 10.5 percent; 2 = 30.5 percent; 3 = 50.5 percent; 4 = 70.5 percent; 5 = 90.5 percent). Ale mol: Aleurites moluccana (n = 15); Gre rob: Grevillea robusta (n = 5); Psi cat: Psidium cattleianum (n = 15); Psi gua: Psidium guajava (n = 15); Spa cam: Spathodea campanulata (n = 5); Sch ter: Schinus terebinthifolius (n = 15); Too cil: Toona ciliata (n = 5); Cae maj: Caesalpinia major (n=??); Cli hir: Clidemia hirta (n = 15); Lan cam: Lantana camara (n = 5); Opl hir: Oplismenus hirtellus (n = 15); Oxa cor: Oxalis corniculata (n = 15); Pas sub: Passiflora suberosa (n = 15); Pas edu: Passiflora edulis (n = 5); Rub ros: Rubus rosifolius (n = 5). Date Ale1 Gre ro b PS1 .cat PS1 . gua Spa Sc hter T00 C1'1 Cae• Cli hir Lan Opl hir Oxa Pas subPas eduRub ros mo cam maJ cam cor Apr-04 30.5 7.6 0.0 0.0 0.0 0.0 0.0 5.2 45.5 75.5 70.5 32.8 50.5 21.3 12.8 (8.2) (7.2) (0.0) (0.0) (0.0) (0.0) (0.0) (3.1) (5.2) (8.1) (8.1) (11.9) (14.2) (8.4) (6.2) May-04 30.5 35.5 5.2 2.6 2.6 0.0 0.0 2.6 55.5 80.5 32.8 15.2 65.5 8.2 17.8 ..... (8.1) (5.0) (2.9) (2.6) (2.1) (0.0) (0.0) (2.4) (9.1) (9.5) (11.9) (12.4) (9.4) (5.9) (7.7) VI Jun-04 30.5 65.5 20.5 to.5 10.2 0.0 0.0 2.6 45.5 60.5 20.2 5.2 50.5 2.1 20.5 (0.0) (2.6) (9.7) (13.5) (12.4) (4.3) (14.1) (2.1) (9.8) (8.3) (9.6) (12.2) (1.2) (7.1) (0.0) - __ ..______n _____ 100% ...., c 80% 0 :t:J Ant pia J! ::s 60% c. -.-Elebif 0 c. 40% ...... Bob ela -0 -e-Psymar ~ 0 20% 0% J J A S 0 N· 0 J FMAM J Month ---- Figure B.1 Monthly percentage ofnative fleshy-fruited with mature fruit. Phenology recorded from June 2003 to June 2004. Ant pIa: Antidesmaplatyphyllum (n = 15); Ela bif: Elaeocarpus bifidus (n = 10); Bob ela: Bobea elatior(n =2); Psy mar: Psychotria mariniana (n=15). 100% A- I "'• C • 0 80% ;; Pip alb .!! :::I 60% Q. ---Psyord 0 Q. 40% . -k - Pou san 'I- 0 --e-Alyoli ';f!. 20% 0% J JASONDJFMAMJ Month Figure B.2. Monthly percentage ofnative fleshy-fruited with mature fruit. Phenology recorded from June 2003 to June 2004. Pip alb: Pipturus albidus (n = 15); Psy ord: Psydrax odoratum (n = 10); Pou san: Pouteria sandwicensis (n = 15); AIy oli: Alyxia oliviformis (n = 10). 116 100% ,1iJ.--"--IiJ.-- C 0 80% :;:; --Psi cat J! ::s 60% c. • Psi gua 0 c. 40% ---k-- eli hir ~ 0 o Lancam ~ 20% 0 0% JJ A SON D J FMAM J Month Figure B.3. Monthly percentage of fleshy-fruited alien species with mature fruit. Phenology recorded from June 2003 to June 2004. Psi cat: Psidium cattleianum (n = 15); Psi gua: Psidium guajava (n = 15); eli hir: Clidemia hirta (n = 15); Lan cam: Lantana camara (n = 5). 100% c 0 80% +l --Schter J! ::s 60% c. • Pas sub 0 c. 40% • -- 1iJ.-- - Pas edu ~ 0 o Rub ros ~ 20% 0 0% JJ A SON D J FMAM J Month Figure B.4. Monthly percentage offleshy-fruited alien species with mature fruit. Phenology recorded from June 2003 to June 2004. Sch ter: Schinus terebinthifolius (n = 15); Pas sub: Passiflora suberosa (n = 15); Pas edu: Passiflora edulis (n = 5); Rub ras: Rubus rosifolius (n = 5). 117 1.2 c 1 0 +:3 --Bid tor J! 0.8 ~ • Can gal c. 0.6 c.0 --.. - Cha ova "'"0 0.4 o Met pol ?fl. 0.2 0 JJ A S 0 NO J FMAM J Month Figure B.S. Monthly percentage of non-neshy-fruited native species with mature fruit. Phenology recorded from June 2003 to June 2004. Bid tor: Eidens torta (n = 15); Can gal: Canavalia galeata(n = 5); Cha obo: Charpentiera obovata (n = 10). Met pol: Metrosideros polymorpha (n = 15). 1.2 c 1 o +:3 J! 0.8 --Mortri ~ go 0.6 • Pis bru c. '0 0.4 --.. - Aca koa ?fl. 0.2 O+-...,...h-IIl-r-llh-IIl--r-tlh-Ih--,--,--,--,----,---, JJ A SON 0 J FMAM J Month Figure B.S. Continued. Monthly percentage ofnon-neshy-fruited native species with mature fruit. Phenology recorded from June 2003 to June 2004. Mor tri: Morinda trimera (n = 5); Pis bru: Pisonia brunoniana (n = 15); Aca koa: Acacia koa (n = 15). 118 1.2 1 c 0 +:I 0.8 --Oplhir J! ~ c. • Oxa cor 0 0.6 c. - -. - Too cil -0 0.4 o Spa cam ie' 0.2 0 JJASONDJFMAMJ J L-.--~ M_Onth ._ Figure B.6. Monthly percentage of non-fleshy-fruited alien species with mature fruit. Phenology recorded from June 2003 to June 2004.0pl hir: Oplismenus hirtellus (n = 15); Oxa cor: Oxalis corniculata (n = 15); Too cil: Toona ciliata (n = 5); Spa cam: Spathodea campanulata (n = 5). 1.2 c 1 o i 0.8 --Ale mol ~ go 0.6 • Gre rob c. '0 0.4 - -. - Cae maj ie 0.2 O+--~~h-Ih-Ih-Ih-Il-r-ll--r-:l..,..,a--r-----r---,---, J JASONDJ FMAMJ Month Figure B.6. Continued. Monthly percentage of non-fleshy-fruited alien species with mature fruit. Phenology recorded from June 2003 to June 2004. Ale mol: Aleurites moluccana (n = 15); Gre rob: Grevillea robusta (n = 5); Cae maj: Caesalpinia major (n=5). 119 100 A eo B Q) 00 00 70 <:[) eo 00 3) .rIt.. <:[) 2IJ 3) 00 2IJ 10 10 .'! ] ..! 0 0 ~ J J A SON D J FMAM J JJ A S 0 N D J FMA M J -Q';; "-' &l &l C 45 D gJ i\J 4J t 40 36 Pol 3) 3J 25 2IJ 20 15 10 10 5 0 0 J J AS o N 0 J FMAM J J J A S 0 N D J F' MA M J Months Figure B.7. Mean (± SE) monthly percentage ofstems with immature and mature fruits by native tree species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 2.5 percent; 2 = 15.5 percent; 3 = 37.5 percent; 4 = 62.5 percent; 5 = 87.5 percent). Dotted lines represent immature fruits and solid lines represent mature fruits. A: Acacia koa (n=15); B: Antidesmaplatyphyllum (n::::: 15); C: Elaeocarpus bifidus (n = 10); D: Bobea elatior (n = 2). Phenology recorded from June 2003 to June 2004. 120 70 70 E F 00 00 5) 6J f-1. 4) 4) 3J 3J ." 1. 20 20 tI.l 'o~ 10 10 ~ 0 0 J J A S o ND J F MAM J JJ A S 0 ND J F MAM J t ·10 -10 'C'';;. -..;....' 70 30 G H 5 00 () 25 t eo ~ 20 4) 15 3J 10 ..... 20 .. 01 5 10 0 0 JJ A S 0 ND J F MA M J -5 Months Figure B.7. Continued. Mean (± SE) monthly percentage ofstems with immature and mature fruits by native tree species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 2.5 percent; 2 = 15.5 percent; 3 = 37.5 percent; 4 = 62.5 percent; 5 = 87.5 percent). Dotted lines represent immature fruits and solid lines represent mature fruits. E: Pisonia brunoniana (n = 15); F: Psychotria mariniana (n=15); G: Metrosideros polymorpha (n = 15); H: Morinda trimera (n = 5). Phenology recorded from June 2003 to June 2004. 121 70 100 I Q) J eo eo 1 BJ 70 4J eo BJ ro 4) r:n 20 3J 20 ~ 10 10 1. 0 0 l J J A SON D J FMAM J J J A S 0 N D J FMA M J '0'Q': "-" ~ 70 K t) eo b !=l-t &l 4J , 3J 20 1t 10 0 JJ A S 0 N D J FMA M J Months Figure B.7. Continued. Mean (± SE) monthly percentage ofstems with immature and mature fruits by native tree species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 2.5 percent; 2 = 15.5 percent; 3 = 37.5 percent; 4 = 62.5 pergent; 5 = 87.5 percent). Dotted lines represent immature fruits and solid lines represent mature fruits. I: Pipturus albidus (n = 15); J: Psydrax odoratum (n = 10); K: Pouteria sandwicensis (n = 15). Phenology recorded from June 2003 to June 2004. 122 70 A 9J B 00 00 70 ro .I" 00 4J ro 3J 4J 3J , 20 .1 20 ] 10 10 ,'·1 l 0 0 ~ JJ A S 0 N D J F MAM J J J A S 0 N D J F MA M J -.. ;£ e." 100 C 100 D '§ 9J 9J () ro i. ro ~ 70 70 ..: "1. !=LI eo eo .11 '. " 00 ro .. 4J 4J 3J I 3J .f .J 20 I.. 20 10 10 0 i. 0 J J A S 0 N D J F MA M J J J A S 0 N D J F MA M J Months Figure B.S. Mean (± SE) monthly percentage of stems with immature and mature fruits by alien tree species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 2.5 percent; 2 = 15.5 percent; 3 = 37.5 percent; 4 = 62.5 percent; 5 = 87.5 percent). Dotted lines represent immature fruits and solid lines represent mature fruits. A: Aleurites moluccana (n = 15); B: Grevillea robusta (n = 5); C: Psidium cattleianum (n =15); D: Psidium guajava (n = 15). Phenology recorded from June 2003 to June 2004. 123 Figure B.8. Continued. Mean (± SE) monthly percentage ofstems with immature and mature fruits by alien tree species. Means were calculated by assigning values to phenology categories 1-5 (0 =none; 1 =2.5 percent; 2 = 15.5 percent; 3 = 37.5 percent; 4 = 62.5 percent; 5 = 87.5 percent). Dotted lines represent immature fruits and solid lines represent mature fruits. E: Spathodea campanulata (n = 5); F: Schinus terebinthifolius (n = 15); G: Toona ciliata (n = 5). Phenology recorded from June 2003 to June 2004. 124 9J A 9J B a:> S) 70 f--E, 70 fO fO ro 5) : olD olD 30 3J rn 20 20 ~ 10 10 0 0 JJ S 0 N J FMAM J ~ JJ A S 0 N D J F MAM J ·10 A D 'Q ~ ---.. 45 fO D olD c '5 5) (,) 35 a3 olD ~ 30 25 30 , ' 20 II, ' J.llf 15 2J) , 10 10 5 0 0 J J A S 0 N D J F MAM J JJ A S 0 N D J FMAM J Months Figure B.9. Mean (± SE) monthly percentage of stems with immature and mature fruits by native shrub and liana species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 2.5 percent; 2 = 15.5 percent; 3 = 37.5 percent; 4 = 62.5 percent; 5 = 87.5 percent). Dotted lines represent immature fruits and solid lines represent mature fruits. A: Alyxia oliviformis (n = 10); B: Bidens torta (n=15); C: Charpentiera obovata (n = 10); D: Canavalia galeata (n = 5). Phenology recorded from June 2003 to June 2004. 125 70 9J A B flO 00 70 ffi flO 4J ffi 4) 30 30 20 00 20 10 10 l't l 0 0 i J J A S 0 N D J F MAM J -10 JJ A S 0 N D J F MAM J -Q' ~ "-" 120 flO c D li 100 ffi I;j ~ .!. 00 4) ~ 00 l 30 : 4J 20 20 .I 10 0 0 J J A S o N [) J FM A M J J J A SON [) J F MAM J Months Figure B.IO. Mean (± SE) monthly percentage of stems with immature and mature fruits by alien shrub and liana species. Means were calculated by assigning values to phenology categories 1-5 (0 = none; 1 = 2.5 percent; 2 = 15.5 percent; 3 = 37.5 percent; 4 = 62.5 percent; 5 = 87.5 percent). Dotted lines represent immature fruits and solid lines represent mature fruits. A: Clidemia hirta (n = 15); B: Lantana camara (n = 5); C: Oplismenus hirtellus (n = 15); D: Oxalis corniculata (n = 15). Phenology recorded from June 2003 to June 2004. 126 8J E eo F 70 fl) eo 4J fl) 4J 3J 3J 20 fI.l 20 10 ] 10 0 0 ~ JJ A S 0 N 0 J F MA M J JJ A S 0 N 0 J F MA M J "Q' €., 45 3J 4) G H "5 2S (,) 35 ~ Po.! 3J 20 2S 15 , 20 . . ,. 15 ..f . 10 10 5 5 0 0 -5 J J AS 0 N 0 J F MA M J J J A S 0 N 0 J F MA M J Months Figure B.IO. Continued. Mean (± SE) monthly percentage ofstems with immature and mature fruits by alien shrub and liana species. Means were calculated by assigning values to phenology categories 1-5 (0:::: none; 1 :::: 2.5 percent; 2:::: 15.5 percent; 3 = 37.5 percent; 4:::: 62.5 percent; 5 :::: 87.5 percent). Dotted lines represent immature fruits and solid lines represent mature fruits. E: Passiflora suberosa (n:::: 15); F: Passiflora edulis (n :::: 5); G: Rubus rosifolius (n:::: 5); H: Caesalpinia major (n::::5). Phenology recorded from June 2003 to June 2004. 127 LITERATURE CITED Ariyoshi R. 1986. Roundup: island ranching. Aloha 9: 24-32. Baker D. 1989. Islands on the edge. Amicus Journal 11 : 40-43. Baskin CC, Baskin JM. 2001. Seeds: ecology, biogeography and evolution ofdormancy and germination. Academic Press, San Diego, California. Benitez-Malvido J. 1998. Impact offorest fragmentation on seedling abundance in a tropical rain forest. Conservation Biology 12: 380-389. Bierregaard RO, Jr., Lovejoy T, Kapos V, dos Santos A, Hutchings R. 1992. the biological dynamics oftropical rain forest fragments. BioScience 42: 859-866. Bonham, CD. 1989. Measurements for terrestrial vegetation. Wiley & Sons, NY. Bossuyt B, Heyn M, Hermy M. 2002. Seed bank and vegetation composition offorest stands ofvarying age in central Belgium: consequences for regeneration of ancient forest vegetation. Plant Ecology 162: 33-48. Bruegmann MM. 1996. Hawaii's dry forests. Endangered Species Bulletin 11:26-27. Burton PJ, Bazzaz FA. 1991. Tree seedling emergence on interactive temperature and moisture gradients and in patches old-field. American Journal ofBotany 78: 131 149. Cabin RJ, Weller SG, Lorence DH, Flynn TW, Sakai AK, Sandquist D, Hadway L. 2000. Effects oflong-term ungulate exclusion and recent alien species control on the preservation and restoration ofa Hawaiian tropical dry forest. Conservation Biology 14: 439-453. Chapman CA, Chapman LJ. 1996. Frugivory and the fate ofdispersed and non-dispersed seeds ofsix African tree species. Journal ofTropical Ecology 12: 491-504. Cheke AS, Nanakorn W, Yankoses C. 1979. Dormancy and dispersal ofseeds of secondary forest species under canopy ofa primary rain forest in northern Thailand. Biotropica 11: 88-95 Chimera C. 2005. Investigating seed dispersal and seed predation in a Hawaiian dry forest community. Department ofBotany. University ofHawaii, Manoa. Cook RE. 1979. Patterns ofjuvenile mortality and recruitment in plants. In: Solbring aT, Jain-S, Johnson GB, Raven PRo eds. Topics in Plant Population Biology. Columbia University Press, New York. 128 Cook RE. 1980. The biology ofseeds in the soil. In: Solbrig OT. ed. Demography and Evolution in Plant Populations. University ofCalifornia Press, Berkeley. Crawley MJ. 1990. The population dynamics ofplants. Phil Trans R Soc Lond B 330: 125-140. Crist TO, Guertin DS, Wiens JA, Milne BT. 1992. Animal movement in heterogeneous landscapes: an experiment with Eleodes beetles in short grass prairie. Functional Ecology 6: 536-544. Cuddihy LW, Stone CPo 1990. Alteration ofnative Hawaiian vegetation. Cooperative National Park Resources Studies Unit, University ofHawaii, Honolulu. Debussche M, Isenmann P. 1994. Bird-dispersed seed rain and seedling establishment in patchy Mediterranean vegetation. Oikos 69: 414-426. Drake DR. 1992. Seed dispersal ofMetrosideros polymorpha (Myrtaceae): a pioneer tree ofHawaiian lava flows. American Journal o/Botany 79: 1224-1228. Drake DR. 1998. Relationships among seed rain, seed bank and vegetation ofa Hawaiian forest. Journal o/Vegetation Science 9: 103-112. Drake DR, Mulder PH, Towns DR, Daugherty CH. 2002. The biology ofinsularity: an introduction. Journal o/Biogeography 29: 563-569. Delgado Gracia JD. 2002. Interactions between introduced rats and frugivore bird-plant system in relict island forest. Journal o/Natural History 36: 1247-1258. Ericksson 0, Ehrlen J. 1992. Seed and microsite limitation ofrecruitment in plant populations. Oecologica 91: 360-364. Ferguson RN, Drake DR. 1999. Influence ofvegetation structure on spatial patterns of seed deposition by birds. New Zealand Journal 0/Botany 37: 671-677. Fleming TH, Heithaus ER. 1981. Frugivorous bats, seed shadows, and the structure of tropical forests. Biotropica 13: 45-53. Fowler NL. 1986. Density-dependent population regulation in a Texas grassland. Ecology 67: 545-554. Franklin J, Drake DR, Bolick LA, Smith DS, Motley TJ. 1999. Rain forest composition and patterns ofsecondary succession in the Vava'u Island group, Tonga. Journal o/Vegetation Science 10: 51-64. 129 Garrison J. 2005. PhD dissertation. Department ofZoology. University ofHawaii, Manoa. Garwood NC. 1989. Tropical soil seed bank: a review. In: Leck MA, Parker VT, Simpson RL(eds.) Ecology ofsoil seed banks. Pp. 149-209. Academic Press Inc. San Diego, CA. Gosz, JR. 1991. Fundamental ecological characteristics oflandscape boundaries. In Hollan MJ, Risser PG, Naiman RJ (eds.) Ecotones: the role oflandscape boundaries in the management and restoration ofchanging environments. Chapman and Hall, New York, New York. Pp. 8-30 Guevara S, Laborde J. 1993. Monitoring seed dispersal at isolated standing trees in tropical pastures: consequences for local species availability. Vegetatio 107/108: 319-338. Hammond DS, Brown VK. 1995. Seed size ofwoody plants in relation to disturbance, dispersal, soil type in wet neotropical forests. Ecology 76: 2544-2561. Harper JL. 1977. Population biology ofplants. Academic Press, London. Harper JL, Lovell PH, Moore KG. 1970. The shapes and sizes ofseeds. Annual Review of Ecology and Systematics 1: 327-356. Harris LD. 1984. The fragmented forest. University ofChicago Press, Chicago, Illinois. Honouliuli Master Plan 2001-2005. The Nature Conservancy ofHawaii, O'ahu Program. P.O. Box 971665 Waipahu, HI. Hopkins MS, Graham AW. 1984. Viable soil seed banks in disturbed lowland tropical rainforest sites in North Queensland. Australian Journal ofEcology 9: 71-79. Houle G. 1992. Spatial relationship between seed and seedling abundance and mortality in a deciduous forest in northeastern North America. Journal ofEcology 80: 99 108. Howe HF, Primack RB. 1975. Differential seed dispersal by birds ofthe tree Casearia nitida (Flacourtiaceae). Biotropica 7(4): 278-283. Howe HF, Schupp EW, Westley LC. 1985. Early consequences ofseed dispersal for a neotropical tree (Virola surinamensis). Ecology 66(3): 781-791. Howe HF, Smallwood J. 1982. Ecology ofseed dispersal. Annual Review ofEcology and Systematics 13: 201-228. 130 Hughes F, Vitousek PM, Tunison T. 1991. Alien grass invasion and fIre in seasonal submontane zone ofHawaii. Ecology 72: 743-746. Hughes JW, Fahey TJ, Bormann FH. 1988. Population persistence and reproductive ecology ofa forest herb: Aster acuminatus. American Journal o/Botany 75: 1057 1064. Hughes JW, Fahey TJ. 1988. Seed dispersal and colonization in a disturbed northern hardwood forest. Bulletin o/the Torrey Botanical Club 115: 89-99. Izhaki I. 2002. The role offruit traits in determining fruit removal in east Mediterranean ecosystems. In D.J. Levey, W.R. Silva and M. Galetti (eds.). Seed dispersal and frugivory: ecology, evolution and conservation. CABI Publishing, New York. Pp. 161-175 James HF. 1995. Prehistoric change to diversity and ecosystem dynamics on oceanic islands. In: Vitousek P, Loope L, Adsersen H. ed. Biological diversity and ecosystem function on islands. Springer-Verlag, Heidlberg, Germany. James HF, Olson SL. 1991. Description ofthirty-two new species ofbirds from the Hawaiian Islands. Part 2. Passeriformes. Ornithological Monographs 46. The American Ornithological Union, Washington, D.C. Janzen DH. 1983. No park is an island: increase in interference from outside as park size decreases. Gikas 41:402-410. Johnson AR, Milne BT, Wiens JA. 1992. Diffusion in fractal landscapes: simulations and experimental studies ofTenebrionid beetle movements. Ecology 73: 1968 1983. Jordano P. 2001. Fruits and frugivory. In M. Fenner (ed). Seeds: the ecology of regeneration in plant communities. CABI, Publishing. New York, NY. Pp.125 165 Kapos V. 1989. Effects ofisolation on the water status offorest patches in the Brazilian Amazon. Journal o/Tropical Ecology 5:173-185. Kirch PV. 1982. The impact ofthe prehistoric Polynesians on the Hawaiian Ecosystem. Pacific Science 36: 1-14. Kitayama K, Mueller-Dombois D. 1995 Biological invasion on an oceanic island mountain: do alien plant species have wider ecological ranges than native species? Journal o/Vegetation Science 6: 667-674. 131 Klinkhamer PGL, de Jong TJ. 1989. A deterministic model to study the importance of density-dependence for regulation and outcome ofintra-specific competition in populations ofsparse plants. Acta Bot Neerl38: 57-65. Laurance WF, Bierregaard RD. (eds.) 1997. Tropical forest remnants: ecology, management, and conservation offragmented communities. University of Chicago Press, Chicago. Leck MA. 1989. Functional soil seed banks. In: Leck MA, Parker VT, Simpson RL. Ed. Ecology ofSoil Seed Banks. Academic Press. San Diego. Leishman MR, Westoby M, Jurado E. 1995. Correlates ofseed size variation: a comparison among five temperate floras. Journal 0/Ecology 83: 517-530. Leishman MR, Wright IJ, Moles AT, Westoby M. 2000. The evolutionary ecology of seed size. In: Fenner M. eds. Seeds; the ecology ofregeneration in plant communities. CABI Publishing. New York, NY. Levey DJ. 1987. Seed size and fruit-handling techniques ofavian frugivores. The American Naturalist 129: 471-485. Loiselle BA, Blake JG. 2002. Potential consequences ofextinction offrugivorous birds for shrubs ofa tropical wet forest. In Levey DJ, Silva WR, Galetti M (eds.). Seed dispersal and frugivory: ecology, evolution and conservation. CABI Publishing, New York. Pp. 397-406. Loope LL, Mueller-Dombois D. 1989. Characteristics ofinvaded islands, with special reference to Hawaii. In: Drake JA, Mooney HA, de Castri F, Groves RH, Kruger FJ, Rejmanek M, Williamson M. eds. Biological invasions: a global perspective. John Wiley and Sons. Chichester. Loope LL. 1998. Hawaii and the Pacific Islands. In: Mac MJ, Opler PA, Puckett Haecker CE, Doran PD ed. Status and trends ofthe nation's biological resources. 2 vols. U.S. Department ofthe Interior, U.S. Geological Survey, Reston. Louda SM. 1982. Limitation ofthe recruitment ofthe shrub Haplopappus squarrosus (Asteraceae) by flower- and seed-feeding insects. Journal o/Ecology 70: 43-53. Louda SM, Zedler PH. 1985. Predation in insular plant dynamics: an experimental assessment ofpost dispersal fruit survival, Enewetak Atoll, Marshall Islands. American Journal o/Botany 72: 438-445. Lovejoy TE, Rankin JM, Bierregaard RO, Brown Jr. KS, Emmons LH, van der Voort ME. 1984. Ecosystem decay ofAmazon forest remnants. In: Nitecki MH ed. Extinctions. University ofChicago Press, Chicago. 132 Lugo AB. 1992. Tree plantations for rehabilitating damaged forest lands in the tropics. In: Ecosystem rehabilitation: preamble to sustainable development. Volume 2: Ecosystem analysis and synthesis. M. K. Wali ed. SPB Academic Publishing, The Hague, Netherlands. Pp. 247-255. Malcom J. 1994. Edge effects in central Amazonian forest fragments. Ecology 75:2438 2445. Martin TE. 1985. Resource selection by tropical frugivorous birds: integrating multiple interactions. Oecologia 66: 563-573. Matlack CK. 1994a. Plant species migration in a mixed-history forest landscape in eastern North America. Ecology 75: 1491-1502. Matlack CK. 1994b. Vegetation dynamics offorest edges: trends in space and successional time. Journal ofEcology 82: 113-123. McClanahan TR. 1986. Seed dispersal from vegetation islands. Ecological Modeling 32: 301-310. McClanahan TR, WolfRW. 1993. Accelerating forest succession in a fragmented landscape: the role ofbirds and perches. Conservation Biology 2: 279-291. McConkey KR, Drake DR. 2002. Extinct pigeons and declining bat populations: are large seeds still being dispersed in the tropical Pacific? In: DJ Levey, WR Silva, M Galetti ed. Seed Dispersal and Frugivory: Ecology, Evolution and Conservation. Mederios AC. 2004. PhD dissertation. Department ofBotany. University ofHawaii, Manoa. Mederios AC, Loope LL, Anderson S. 1993. Differential colonization by epiphytes on native (Cibotium spp.) tree-ferns in a Hawaiian rain forest. Selbyana 14: 71-74. Mederios AC, Loope LL, Hobdy R. 1986. Status ofnative flowering plant species on the south slope ofHaleakala, East Maui, Hawaii. Cooperative National Park Resources Studies Unit, University ofHawaii, Honolulu. Technical Report 59. Meehan HJ, McConkey KR, Drake DR. 2002. Potential disruptions to seed dispersal mutualisms in Tonga, Western Polynesia. Journal ofBiogeography 29: 695-712. MehrhoffL. 1993. Rare plants in Hawaii: a status report. Plant Conservation 7: 1-2. 133 Mills SL. 1995. Edge effects and isolation: red-backed voles, on forest remnants. Conservation Biology 9: 395-403. Moles AT, Drake DR. 1999. Potential contributions ofthe seed rain and seed bank to regeneration ofnative forest under plantation pine in New Zealand. New Zealand Journal ofBotany 37: 83-93. Mooney HA, Drake F (eds.) 1986. The ecology ofbiological invasions ofNorth America and Hawaii. Springer-Verlag. New York, NY. Murcia C. 1995. Edge effects in fragmented forests: implications for conservation. Trends in Ecology andEvolution 73: 68-77. Myers N, Mittermeier RA, Mittermeier CG, da Foneseca, Gab Kent J. 2000. Biodiversity hotspots for conservation priorities. Nature 403: 853-858. Nelson RE. 1967. Records and maps offorest types in Hawaii. U.S.D.A. Forest Service Resource Bulletin. PSW-8: 1-22. Olson SL, James HF. 1982. Prodromus ofthe fossil avifauna ofthe Hawaiian Islands. Smithsonian Contributions to Zoology 365: 1-59. Olson SL, James HF. 1991. Descriptions ofthirty-two new species ofbirds from the Hawaiian Islands. Part 1. Non-passeriformes. Ornithological Monographs 45. The American Ornithological Union, Washington, D.C. Peart DR. 1989. Species interactions in a successional grassland; Seed rain and seedling recruitment. Journal ofEcology 77: 252-266. Peco B, Traba J, Levassor C, Sanchez AM, Azcarate FM. 2003. Seed size, shape and persistence in dry Mediterranean grass and scrublands. Seed Science Research 13: 87-95. Peterson CJ, Pickett STA. 1990. Microsite and elevational influences on early forest regeneration after catastrophic windthrow. Journal ofVegetation Science 1: 657 662. Pratt HD, Bruner PL, Berrett DG. 1987. A Field Guide to The Birds ofHawaii and the Tropical Pacific. Princeton University Press. Princeton, New Jersey. Price OF. 2004. Indirect evidence that frugivorous birds track fluctuating fruit resources among rainforest patches in the Northern Territory, Australia. Austral Ecology 29: 136-144. 134 Reader RJ, Buck J. 1991. Control ofseedling density on disturbed ground: role of seedling establishment for some mid-successional, old-field species. Canadian Journal ofBotany 69: 773-777. Robinson GR, Handel SN. 1993. Forest restoration on a closed landfill: Rapid addition ofnew species by bird dispersaL Conservation Biology 7: 271-278. Ryszkowski L. 1992. Energy and material flows across boundaries in agricultural landscapes. In: Hansen AJ & di Castri F. ed. Landscape boundaries: consequences for biotic diversity in ecological flows. Springer-Verlag, New York, New York, USA. Saunders DA, Hobbs RJ, Margules C. 1991. Biological consequences ofecosystem fragments: a review. Conservation Biology 5: 18-32. Schupp EW. 1990. Annual variation in seed fall, post dispersal predation and recruitment ofa neotropical tree. Ecology 71: 504-515. Scott JM, Mountainspring S, Ramsey FL, Kepler CB. 1986. Forest bird communities of the Hawaiian Islands: their dynamics, ecology, and conservation. Studies in Avian Biology 9. Sem G, Enright NJ. 1995. The soil seed bank in Agathis australis (D. Don) LindL (kauri) forests ofnorthem New Zealand. New ZealandJournal ofBotany 33: 221-235. Sizer N.1992. The impact ofedge formation on regeneration and litterfall in a tropical rain forest fragment in Amazonia. Ph.D. dissertation. University ofCambridge, Cambridge, United Kingdom. Smith AJ. 1975. Invasion and ecesis ofbird-disseminated woody plants in a temperate forest. Ecology 56: 19-34. Smith CW, Tunison JT. 1992. Fire and alien plants in Hawaii: research and management implications for native ecosystems. In: Stone CP, Smith SW, Tunison JT ed. Alien plant invasions in native ecosystems ofHawaii: management and research. University ofHawaii Cooperative National Park Resources Studies Unit. Honolulu, HI. Spears EE, Jr. 1987. Island and mainland pollination ecology ofCentrosoma virginianum and Opuntia stricta. Journal ofEcology 75: 351-362. Steadman RW. 1995. Prehistoric extinctions ofPacific island birds: biodiversity meets zooarcheology. Science 267: 1123-1131. 135 Stone CPo 1985. Alien animals in Hawaii's native ecosystems: toward controlling the adverse effects ofintroduced vertebrates. In: Stone CP and Scott M ed. Hawaii's terrestrial ecosystems: preservation and management. Cooperative National Park Resources Studies Unit, University ofHawaii, Honolulu. Swaine MD, Hall JB. 1983. Early succession on cleared forest land in Ghana. Journal of Ecology 71: 601-627. Tabarelli M, Mantovanni W, Peres CA. 1999. Effects ofhabitat fragmentation on plant guild structure in the montane Atlantic forest ofsoutheastern Brazil. Biological Conservation 91: 119-127. Temple SA. 1977. Plant-animal mutualism: co-evolution with Dodo leads to near extinction ofplant. Science 197: 885-886. Thompson K. 1987. Seeds and seed banks. New Phytologist 106: 23-34. Thompson K 1992. The functional ecology ofseed banks. In: Fenner M ed. Seeds: the ecology ofregeneration in plant communities.. C.A.B. International. Wallingford. Vitousek PM. 1988. Diversity and biological invasions ofoceanic islands. In: Wilson EO ed. Biodiversity. National Academy Press. Washington DC. Vitousek PM, Loope LL, Adsersen H. (eds). 1995. Islands: biological diversity and ecosystem function. Springer-Verlag, Berlin. Wagner WL, Herbst DR, Sohmer SH. 1999. Manual ofFlowering Plants ofHawaii. University ofHawaii Press, Bishop Museum Press. Honolulu, HI. Watson DM. 2002. A conceptual framework for studying species compositions in fragments, islands and other patchy ecosystems. Journal ofBiogeography 29: 823-834. Wenny DG. 2000. Advantages ofseed dispersal: a re-evaluation ofdirected dispersal. Evolutionary Ecology Research 3: 51-74. Whitmore TC. 1983. Secondary succession from seed in tropical rainforests. Forestry Abstracts 44: 767-779. Whittaker RJ. 1998. Island biogeography: ecology, evolution, and conservation. Oxford University Press, Oxford. 136 Wilson MF, Traveset A. 2000. The ecology ofseed dispersal. In: Fenner M ed. Seeds: the ecology ofregeneration in plant communities. CABI, Wallingford, UK. Wilson MF, Crome FR. 1989. Patterns ofseed rain at the edge ofa tropical Queensland rain forest. Journal ojTropical Ecology 5: 301-308. Wiser SK, Drake DR, Burrows LE, Sykes WR. 2002. The potential for long term persistence offorest fragments on a large island in western Polynesia. Journal of Biogeography 29: 767-787. Young KR, Ewe! JJ, Brown BJ. 1987. Seed dynamics during forest succession in Costa Rica. Vegetatio 71: 157-173. 137