Mastozoología Neotropical ISSN: 0327-9383 [email protected] Sociedad Argentina para el Estudio de los Mamíferos Argentina
Shepherd, John D.; Ditgen, Rebecca S. Human use and small mammal communities of Araucaria forests in Neuquén, Argentina Mastozoología Neotropical, vol. 12, núm. 2, julio-diciembre, 2005, pp. 217-226 Sociedad Argentina para el Estudio de los Mamíferos Tucumán, Argentina
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HUMAN USE AND SMALL MAMMAL COMMUNITIES OF ARAUCARIA FORESTS IN NEUQUÉN, ARGENTINA
John D. Shepherd1 and Rebecca S. Ditgen2
1 Department of Biology, College of Liberal Arts, Mercer University, Macon, GA 31207 USA, Telé- fono: 1-478-301-2705, 54-2972-491747,
ABSTRACT: Small mammals were sampled in five closed, humid, Araucaria araucana for- ests that differed in the degree of anthropogenic disturbance in southwestern Neuquén province. Nine species were captured in 3416 trap nights. Abrothrix longipilis and Oligoryzomys longicaudatus made up 88% of all captures. Small mammal relative abundance was 52 times higher where grazing was absent compared to a site with intense grazing pressure. Seed predation, primarily by livestock and feral exotic mammals, varied from 59.7% to 15.1% of marked seeds per day. Small mammal community productivity and composition were corre- lated with understory structure (Mantel test, r = 0.529, p = 0.04), and with rates of seed predation (r = -0.91, n = 4, p = 0.08). Forests with less complex understories had fewer captures and lower mammal diversity. Exotic large mammals appear to affect native small mammals by simplifying the structure of the forest understory and by competing for seeds. Four native species (Abrothrix longipilis, Oligoryzomys longicaudatus, Chelemys macronyx, and Irenomys tarsalis) ate Araucaria piñones. Anthropogenic changes in small mammal communities indicate that management of feral and domestic mammals needs to be a prominent part of the conservation of these majestic forests.
Key words. Araucaria araucana. Exotic species. Human impact. Seed predation. Small mammals.
INTRODUCTION of all Argentine araucaria forests lie within Parque Nacional Lanín (PNL) in southwestern Araucaria araucana dominates xerophytic Neuquén Province, where they are used for Andean forests of northwestern Patagonia and grazing, firewood extraction, and seed harvest. adjacent Chile in pure stands and mixed with Clearly, one of the challenges for PNL is to Nothofagus species (Roig, 1998), but exploi- balance this human use and the Park’s conser- tation in the 20th century resulted in a sharp vation mission (Martín and Chehébar, 2001). decline in the health and distribution of these While anecdotal information abounds about the forests (Aagesen, 1998). In spite of recent pro- impact of people on these forests, systematic tection, the future of araucaria communities is assessment is recent. For example, Sanguinetti uncertain and precarious in many areas. et al. (2001a, 2001b, 2002) have initiated stud- Rechene (2000) estimated that over 60% of ies on the effects of grazing and seed harvest the remaining araucaria forests in Argentina on forest regeneration. Despite the efforts to are now in a degraded state. About one third understand the impacts on regeneration, little
Recibido 2 febrero 2005. Aceptación final 6 junio 2005. 218 Mastozoología Neotropical, 12(2):217-226, Mendoza, 2005 J. D. Shepherd and R. S. Ditgen www.cricyt.edu.ar/mn.htm is known of the effects of human disturbance variety of reasons. First, because small mam- on forest elements other than Araucaria itself. mals consume a conspicuous food resource in Since Araucaria is dominant in these for- the forest (Araucaria mast), they represent a ests, it will influence many other species in key link in the forest food chain. Second, the the community. Araucaria’s influence may be community has comparatively high diversity, heightened because it has a prominent masting endemism, and productivity (Pearson, 1983; cycle in which seed production varies more Monjeau et al., 1997; Pardiñas et al., 2003). than twentyfold between mast and inter-mast Third, small mammals partition habitat at both years (Sanguinetti et al., 2001a, 2001b, 2002). the coarse and fine scale (Patterson et al., 1990; Araucaria cycles have greater amplitude and Lozada et al., 2000). Fourth, these species higher seed production than those of northern differ greatly in their dietary proportions of temperate forests, where masting contributes animal matter, fungi and vegetation, and seeds to population fluctuations among small mam- and fruits (Meserve et al., 1988). As a result, mals that have far-reaching consequences changes in habitat structure and food avail- (Ostfeld et al., 1996). In pure stands of Arau- ability are likely to manifest themselves in the caria or in Araucaria-Nothofagus mixed for- community. Fifth, seed harvest and grazing are ests, such effects are likely amplified by the likely to act like hunting (Redford, 1992), so dominance of this single species with large that human impact may be discernible in the nutritious seeds. Human seed gathering and small mammal community, even though it can the use of the seed crop as forage for live- not be seen in forest structure. For these rea- stock remove a potentially important food sons, we studied small mammal communities resource for native animals. Since small mam- in Araucaria forests that differ in the level of mals may act as seed dispersers as well as human activity. We also made preliminary seed predators, they represent a key link in assessment of the relationship of small mam- forest food webs. Community structure may mals to the seed crop as seed predators. track changes in natural masting cycles and anthropogenic changes in seed availability and MATERIALS AND METHODS forest structure. We chose five closed, humid Araucaria forests Pearson and Pearson (1982) found that the between 1200 to 1400 m in elevation in the vicin- Patagonian forest small mammal fauna con- ity of PNL in southwestern Neuquén. These for- sisted of six “forest endemic” and three “wide- ests all consisted of mixtures of Araucaria ranging” species also found in the steppe, with araucana, Nothofagus pumilio and N. antarctica. more semi-fossorial, terrestrial, and scansorial The level of human impact varied directly with small mammal species than Panamanian for- ease of access from very intense to modest (Table 1). In some areas, people establish summer “puestos” ests. The small mammal faunas of the western near which they graze livestock in meadows and in (Distrito Occidental) and sub-Andean districts araucaria forests. In the fall, herds are encouraged (Distrito Subandino) of the Patagonian Phyto- to forage on the araucaria seed fall. Whole com- geographic Province appeared as a uniform munities extract firewood for winter use through- and very distinct cluster in the analysis of out accessible areas. Collecting of araucaria seeds, Pardiñas et al. (2003). These same species (in “piñones”, occurs over a broad area. The Tromen data from Rio Negro and Chubut) formed a forest is protected by virtue of its location between distinct biogeographic group that represented the border with Chile and the Argentine customs the Andean forest and Sub-Andean and immigration post. Collecting seeds occurs sporadically. megabiozones (Monjeau et al., 1997). These The 2002 field season was a year of moderate to forests appear to contain a rich, distinctive low seed productivity (Sanguinetti et al., 2002). assemblage of small mammals. Estimated seed production in the Tromen forest in Small mammal communities of Araucaria 2002 was 228 kg/ha, only 34% as much as in 2000. forests are likely to serve as useful indicators Similarly at Rucachoroi, production was 24% of of forest integrity and human impact for a the peak in the East and 13% in the West. In a HUMAN USE AND SMALL MAMMALS OF ARAUCARIA FORESTS 219
Table 1 Human impacts at small mammal study sites.
HUMAN IMPACTS Grazing pressure Firewood gathering Seed collection Rucachoroi East, E heavy present present Rucachoroi West, W moderate present present Remeco, R moderate light present Chiquilihuín, C light to moderate light present Tromen, T none none present
year like 2002, there are very few seeds on the Since seed scales were removed from the forest forest floor, even immediately after the seed fall. floor by predators, the size of each seed fall could In contrast, during a peak, many seeds are on the not be estimated directly from numbers of seed forest floor at the end of the season and a crop of scales remaining. Instead, it was estimated by count- seedling trees enters the population the following ing sterile cone scales that fall from the cones at spring (Sanguinetti, pers. comm.). Because of the the same time as the fertile seed scales. Data from potential importance of production for levels of an ongoing study of pre-dispersal predation on seed predation, the results reported here should be in- scales showed that the number of sterile scales is terpreted within the context of a low-production strongly correlated with the number of seed scales year. (r = 0.86, n = 112, p <0.01, Shepherd and Ditgen, We trapped small mammals during the 2002 seed unpublished data). Scales from the current year’s fall, between late February and early April. At each seed fall were distinguished from those of previ- study site, Sherman live traps were placed on the ous years by color and state of degradation. All ground in the vicinity of 10 to12 Araucaria seed scales were counted in 10 circular quadrats of trees, arranged so that 2 large (model XLF15) and 0.5 m2 located every 2 m on a transect through the 3 small (model LFATDG) traps were placed within center of the seed fall. The density of sterile scales a tree’s seed shadow and a similar group of 5 traps was multiplied by the basal area of the seed tree to was placed nearby off the seed fall. Traps were create a seed fall index that was assumed to be baited with an Araucaria seed scale and a mixture proportional to the total fallen seeds under the of ground peanuts, vegetable oil, oatmeal and tree. Mantecol (a peanut candy bar). Traps were checked Forest understory was sampled by recording each morning. Captured animals were identified, cover at 200 points spaced at 2 meter intervals weighed, and marked with a small spot of paint on along a line transect. At each point, vegetation the hindquarters before release. Trap success (cap- within 3 m above the point was recorded in the tures per trap night) is used as an index of relative following categories: tree, sapling, tree seedling, abundance (Pearson, 1995; Thompson et al., 1998). cane, shrub, grass, forb and cryptogam. Only trees Taxonomy follows Pearson (1995). and cane were identified by species. The presence We estimated the rates of seed predation with of logs, coarse woody debris, and rocks was noted seed scales marked with a spot of yellow paint on at all points; where none of these and no vegeta- the distal part of the scale away from the seed. tion was present, the point was described as bare Marked seed scales were placed in paired groups soil or leaf litter. Understory complexity was de- of 20, with one group within the seed shadow of scribed by counting the number of points in the a female tree and another set nearby outside the following categories: bare soil and/or rocks (sub- seed fall. A daily rate of seed removal was calcu- strate only); substrate plus leaf litter and/or coarse lated from the number of remaining marked scales woody debris including logs; the preceding plus 1 after an interval in which the seed scales were left to 3 different kinds of vegetation. Differences were unattended. At the heavily grazed site, Rucachoroi summarized in an index of understory complexity East, we recorded seed removal rates in early by assigning the above 5 categories a score of 0 to morning and late evening along with the relative 4 and then calculating an average score per point abundance of sheep to compare diurnal and noc- for each stand. Correspondence analysis (Statistica turnal seed predation. 6.1) was used to describe the multidimensional 220 Mastozoología Neotropical, 12(2):217-226, Mendoza, 2005 J. D. Shepherd and R. S. Ditgen www.cricyt.edu.ar/mn.htm pattern of differences among the sample area un- habitat of small mammals; more than half of derstories. the understory was devoid of vegetation and In order to examine the relationship between woody debris. In contrast at Tromen, almost understory structure and small mammal communi- 70% of the understory was vegetation that ties, a Mantel test (Poptools 2.6.2, Hood, 2004) occurred in multiple layers. evaluated correlation between stand dissimilarity matrices based on small mammals trapped and un- The first two dimensions of a correspon- derstory structure. Total individuals captured were dence analysis (Fig. 2) of stand understories used rather than relativized data because commu- accounted for 46% and 37% of inertia respec- nity productivity as well as species composition is tively. The first dimension is related to stand important. composition. Araucaria predominated at Tromen and Rucachoroi East, while the other RESULTS stands had a greater admixture of N. antartica and N. pumilio. Rucachoroi West had the great- Total trapping effort consisted of 3416 trap- est mixture of different plant types, including nights with 347 captures, for an overall trap- the greatest abundance of cane (Chusquea ping success of 10.2%. Of these, 90 were culeou) and shrubs. The correlation between marked, recaptured, animals, so a total of 257 stand coordinate axis 2 and understory com- individual animals were captured (Table 2). plexity index is very high (r = -0.996, Since we used traps of two different sizes, we p<0.001), so this dimension represents under- tested for the effect of trap size on capture story complexity. At Rucachoroi East plant rate. For all sites taken together, the capture litter and bare soil predominated with little rate was higher in larger traps, but not signifi- vegetation surviving grazing pressure. At cantly so (X2 = 3.754, df = 1, p = 0.053). Tromen, herbaceous, tree seedling, and tree Similarly, for those species with more than 20 sapling layers created a much more complex total captures (Oligoryzomys longicaudatus understory. and Abrothrix longipilis), there was no sig- A Mantel test indicated a strong influence nificant effect of trap size on capture rate (X2 of understory structure on the small mammal = 0.937, p = 0.331 and X2 = 3.150, p = 0.076 community (r = 0.529, p = 0.04). Overall respectively, df = 1). We ignored the effect of capture rate (small mammal community pro- trap size in all analyses. ductivity), species richness, and the Shannon index are all higher in stands with greater Human impact and the small understory complexity. mammal community Of the nine species captured, the long-haired Seedfalls, capture rates mouse, A. longipilis, and the long-tailed mouse, and seed predation O. longicaudatus, were the most common, The number of captures per seed tree ranged comprising 88% of all individuals captured from 0 (6 trees) to 13 (1 tree) with an average (Table 2). The Norway rat, Rattus norvegicus, of 3.6 captures per tree. The number of cap- was the only non-native species encountered. tures was not correlated with the seed fall in- Productivity varied greatly between sites. Only dex (r = 0.06, n = 35, p = 0.71), suggesting two animals were caught in over 700 trap that the density of animals was similar under nights at the site (Rucachoroi East) with the all seed trees. In the aggregate, more animals greatest human impact; trap success was over were captured in trap sets off seed falls than 50 times higher in the least impacted forest. on seed falls (X2 = 5.01, df = 1, p = 0.025). The range of understory structure is shown We made 55 daily estimates of daily preda- in Figure 1, which compares the understory tion rates on marked seed scales that were of the two sites that differed most in structure placed in paired groups on and off seed falls and overall trapping success. At Rucachoroi at three of the sites. There was no significant East, heavy grazing has greatly simplified the difference in the predation rate for seeds on HUMAN USE AND SMALL MAMMALS OF ARAUCARIA FORESTS 221
Table 2 Trapping Results. Table shows the total number of individuals captured at each site, the minimum number known alive (MNKA). Relative abundance is trap success (new captures per trap night) relativized to Rucachoroi East as a measure of relative population sizes at the sites. Recapture rate is the number of recaptures as a percentage of total captures of that species.
Rucachoroi Rucachoroi Remeco Chiquilihuin Tromen Total Recapture East West Captures Rate
Abrothrix longipilis 1 18 12 53 40 124 37% Oligoryzomys longicaudatus 1 5 13 18 65 102 11% Dromiciops gliroides 7 1 8 33% Irenomys tarsalis 880% Chelemys macronyx 2 3 1 6 14% Abrothrix olivaceus 2130% Loxodontomys micropus 220% Geoxus valdivianus 110% Rattus norvegicus 2130%
Total Captures: 2 38 32 76 109 257 Trap Nights: 720 738 486 721 751 3416
Relative Abundance: 1.00 18.5 23.7 37.9 52.3
Species: 2 4 6 4 6 Shannon Index: 0.693 1.186 1.253 0.714 0.837
and off seed falls (t = 0.546, df = 54, p = grazed site to 15.1% at Chiquilihuín. At all 0.588). sites, most of the seeds would be eaten within Eaten, or partially eaten, seed scales were found a week of falling from the tree. This predation in traps with A. longipilis, O. longicaudatus, was primarily the work of medium and large Chelemys macronyx, and Irenomys tarsalis. mammals. At Rucachoroi East, the rate of seed Seed scales were sometimes shredded and removal depended on the presence of sheep apparently used as nest material inside the trap. (F3,46= 35.2, p<0.0001). No seed predation Anecdotal observations suggest that Chelemys occurred at night or when no sheep were carries off seedscales and was specifically present. When ‘few’ or ‘many’ sheep were attracted to the seed scales used as bait. Eaten present, the predation rates on marked seeds seed scales were not found with trapped indi- were 27% and 73% per day respectively. Live- viduals of Dromiciops gliroides, Geoxus stock (sheep, goats, and cattle) grazed all sites valdivianus, Loxodontomys micropus, except Tromen. At three sites (Remeco, Abrothrix olivaceus, and R.norvegicus. Tromen, Chiquilihuín), wild hogs (Sus scrofa) Seed predation rates varied greatly between rooted up vegetation, damaged small mammal sites (Fig. 3). Daily rates of removal of marked traps and left scat and prints. Scat of Euro- seeds varied from 59.7% at the most heavily pean red deer (Cervus elaphus) was seen at 222 Mastozoología Neotropical, 12(2):217-226, Mendoza, 2005 J. D. Shepherd and R. S. Ditgen www.cricyt.edu.ar/mn.htm
Rucachoroi East Veg 3
Veg 2
Veg 1
Debris
Substrate
Tromen Veg 3
Veg 2
Veg 1
Debris
Substrate
0 20 40 60 80 100 120 Number of Points
Fig. 1. Understory structure at Rucachoroi East and Tromen. Substrate: points with only bare soil and/or rock; Debris: points with substrate plus leaf litter and/or coarse woody debris including logs; Veg 1-3: points with the preceding plus 1 to 3 different kinds of vegetation. Number of transect sample points sums to 200 for each stand. Structural complexity indices: Tromen (T), 1.97; Rucachoroi West (W), 1.8; Remeco (R), 1.78; Chiquilihuín (C), 1.19; Rucachoroi East (E), 0.85. See methods for index calculation.
Fig. 2. Correspondence analysis of understory structure from five trapping sites. Tree, sapling and seedling refer only to Araucaria; cwd is coarse woody debris. Site symbol abbreviations: Tromen (T), Rucachoroi West (W), Remeco (R), Chiquilihuín (C), Rucachoroi East (E). HUMAN USE AND SMALL MAMMALS OF ARAUCARIA FORESTS 223
Fig. 3. Rates of seed removal. Bars show the average daily rate of removal of marked seeds. The number above each bar is the percentage of seeds expected to survive one week on the ground at the site, based on the daily rates of predation. Sample sizes are given by site names.
Tromen. Since both feral exotic and native We anticipated that human impact could mammals foraged nocturnally, we could not affect small mammal communities either di- measure their predation separately. Field sign rectly or indirectly. Seed predation rates indi- suggested that the primary seed predators were cate that grazing can remove almost the entire hogs at Tromen and hogs and lagomorphs at seed crop in a year of moderate seed produc- Chiquilihuín. The overall capture rate and seed tion. In fact, livestock seed predation is so predation rate were strongly correlated (r = high in intensely-used areas that even in peak -0.91, n = 4, p = 0.081). seed production years it would have a pro- found impact on seed availability for native DISCUSSION small mammals. The correlation of seed pre- dation rates and small mammal captures sug- While mammal species richness and aggregate gests that competition for seeds may limit small diversity varied between our sample areas, the mammal populations in areas with exotic mam- most dramatic impact was on relative abun- mals. Domestic livestock also appear to sim- dance. The site without grazing pressure plify the structure of the forest understory, (Tromen) had small mammal relative abun- thereby removing the microhabitats needed to dance over 50 times higher than the heavily support native biodiversity. Small mammal grazed site; sites with moderate grazing had community structure was strongly related to relative abundance about 20 times higher understory structure. Thus, livestock can play (Table 2). Clearly, small mammal communi- a dual detrimental role: acting directly as com- ties are affected by grazing livestock. In the petitors for food and indirectly by altering extreme case of Rucachoroi East, more than habitat structure. 50% of the forest understory had been reduced Understory complexity and small mammal to bare soil and capture rates were exceed- density are also correlated in northern temper- ingly low. ate forests (Dueser and Shugart, 1978; Smit et 224 Mastozoología Neotropical, 12(2):217-226, Mendoza, 2005 J. D. Shepherd and R. S. Ditgen www.cricyt.edu.ar/mn.htm al., 2001; Schnurr et al., 2004). Smit et al. immediately south of our study area (Pearson (2001) concluded that alteration of vegetation and Pearson, 1982; Pearson, 1995). The small structure was the primary means by which large mammal diversity of Araucaria forests appears herbivores affected small mammals. Through similar to that of botanically more diverse its effect on the small mammal community, forest types in the region. forest understory structure influenced seed and The species that make up the small mammal seedling survival and tree recruitment patterns community may also be a reflection of the (Schnurr et al., 2004). degree to which human impact has altered The problem of feral exotic species is an understory structure. Increasing diversity of issue of longstanding, widespread concern in understory vegetation, like the cane and shrubs Argentina (Daciuk, 1978; Jackson, 1988; common at Rucachoroi West, adds habitat for Bonino, 1999). These species are not just seed species that are less habitat generalists and predators. Veblen et al. (1989) showed that require specific features of the forest for their red deer (C. elaphus) have eliminated some success. Patterson et al. (1990) found that habi- understory species altogether and retarded re- tat selectivity was inversely correlated with generation of forest dominants in Nothofagus abundance and that less common species were forests. Elsewhere, feral hogs reduce native found in more distinctive habitats. They plant species diversity, facilitate invasion by trapped D. gliroides in places with high shrub exotic weeds, and prey on the young of me- and herbaceous cover, but earlier work (Greer, dium-sized mammals (Bratton, 1974; Kotanen, 1965; Mann, 1978; Redford and Eisenberg, 1995). In our study area, park personnel sug- 1992) associates this species with cane thick- gest hogs migrate into the Araucaria in the ets. These studies clearly suggest a necessity autumn where they forage on fallen seeds and for dense understory for this species. I. tarsalis root up the soil for other foods. Their impact is also reported to be associated with thickets on Araucaria forest vegetation and its mam- of cane (Greer, 1965; Mann, 1978; Redford mal biodiversity is not known. We can say and Eisenberg, 1992). Whatever their particu- that even in less accessible areas, feral exotic lar microhabitat requirements, understory sim- medium and large mammals have an impact plification is likely to eliminate such species. on seed fall that is similar to that of moderate Four species, including the two most com- domestic livestock grazing. mon native small mammals (A. longipilis and The two habitat generalists, A. longipilis and O. longicaudatus) eat Araucaria piñones, con- O. longicaudatus, that predominated among firming the key position of small mammals in the small mammals captured are the most the food chain of these forests. As a result, we common species in studies of small mammals expect the Araucaria masting cycle to be re- in Nothofagus forests farther south and west flected in the level of seed predation and ro- in Chile and are habitat generalists (Greer, dent population biology (Ostfeld et al., 1996). 1965; Pearson and Pearson, 1982; Pearson, We have begun a long term study to assess 1983, 1995). Their high capture rate is also a the relationship between small mammal popu- manifestation of our trapping regime, with traps lation dynamics and the Araucaria seed pro- placed in a variety of microhabitats on the duction. C. macronyx did appear to carry off forest floor. Arboreal (D. gliroides and I. groups of seed scales. More recently (May, tarsalis) and semi-fossorial (C. macronyx and 2004), we used automatic cameras to record G. valdivianus) species may be under-repre- C. macronyx carrying off a pile of 20 seeds sented because of trap placement. L. micropus within two hours. We are pursuing further stud- and A. olivaceus are reportedly more common ies to evaluate its interaction with “piñones” in other habitat types (Mann, 1978; Pearson, as a potential seed dispersal agent. 1983, 1995). Our captures included nine of Because of this interaction of rodents and the ten species reported for Nothofagus for- seeds, we expected higher capture rates on the ests in Lanín and Nahuel Huapi National Parks seed fall as a result of their attraction for ro- HUMAN USE AND SMALL MAMMALS OF ARAUCARIA FORESTS 225
dents. Quite the opposite, we found higher in the Great Smoky Mountains National Park. Bul- capture rates off the seed fall, perhaps because letin of the Torrey Botanical Society 101:198-206 CHRISTENSEN J. 2004. Win-win illusions. Conserva- low production and high predation resulted in tion in Practice 5:12-19. few seeds present at any time. The high rates DACIUK J. 1978. Estado actual de las especies de of seed removal by domestic and feral exotic mamíferos introducidos en la Subregion Araucana species appeared to dwarf the rates of preda- (Rep. Argentina) y grado de coacción ejercido en algunos ecosistemas surcordilleranos. Anales de tion by native small mammals. Because of the Parques Nacionales 14:105-130. presence of nocturnal foraging by feral exotic DUESER RD and HH SHUGART. 1978. Microhabitats species (hogs, and perhaps deer), we were not in a forest-floor small mammal fauna. Ecology 59:89- able to measure seed removal rates by native 98. GREER JK. 1965. Mammals of Malleco Province, Chile. small mammals except at the intensely dis- Publications of the Museum, Michigan State Uni- turbed site where the rate was negligible. versity Biological Series 3:53-151. Human use can clearly alter the small mam- HOOD GM. 2004. Pop Tools version 2.6.2 http:// mal fauna of Araucaria forests. The aggregate www.cse.csiro.au/poptools JACKSON J. 1988. Terrestrial mammalian pests in Ar- impact of intense grazing and firewood col- gentina: an overview. Proceedings of Vertebrate Pest lection can greatly simplify the forest under- Conference 13:196-198. story and essentially eliminate these native KOTANEN PM. 1995. Responses of vegetation to a animals. The recent conservation literature changing regime of disturbance: effects of feral pigs in a California coastal prairie. Ecography 18:190- (e.g., Brandon et al., 1998; Christensen, 2004) 199. suggests that successful implementation of LOZADA M, N GUTHMANN, and N BACCALA. 2000. sustainable human use requires on-going moni- Microhabitat selection of five sigmodontine rodents toring and active adaptive management. in a forest-steppe transition zone in northwest Patagonia. Studies in Neotropical Fauna and Envi- Clearly, management of the impact of feral ronment 35:85-90 and domestic mammals needs to be a promi- MANN G. 1978. Los pequeños mamíferos de Chile. nent part of the conservation of these majestic Gayana, Zoología No. 40, Editorial de la Universidad forests. de Concepción 342 pp. MARTÍN C and C CHEHÉBAR. 2001. The national parks of Argentinian Patagonia – management poli- ACKNOWLEDGEMENTS cies for conservation, public use, rural settlements and indigenous communities. Journal of the Royal This work was supported in part by a grant from the Society of New Zealand 31:845-864. College of Liberal Arts of Mercer University, Macon MESERVE PL, BK LANG, and BD PATTERSON. 1988. Georgia. The Corporación Interstadual Pulmarí allowed Trophic relationships of small mammals in a Chil- access to the Remeco site and provided housing and ean temperate rainforest. Journal of Mammalogy logistical support. Help was provided at all stages by 69:721-730. personnel of Parque Nacional Lanín, especially by Javier MONJEAU JA, RS SIKES, EC BIRNEY, N Sanguinetti. Two reviewers made helpful comments that GUTHMANN, and CJ PHILLIPS. 1997. Small mam- resulted in improvements in the manuscript. mal community composition within the major land- scape divisions of Patagonia, southern Argentina. Mastozoología Neotropical 4:113-127. LITERATURE CITED OSTFELD RS, CG JONES and JO WOLFF. 1996. Of mice and mast. Bioscience 46:323-330. AAGESEN DL. 1998. Indigenous resource rights and PARDIÑAS UFJ, P TETA, S CIRIGNOLI and DH conservation of the monkey-puzzle tree (Araucaria MODESTA. 2003. Micromamíferos araucana, Araucariaceae): A case study from south- (Didelphimorphia y Rodentia) de Norpatagonia ex- ern Chile. Economic Botany 52:146-160. tra andina, Argentina: taxonomía alfa y biogeografía. BONINO NA. 1999. Introduced mammals in Patagonia, Mastozoología Neotropical 10:69-113. southern Argentina: consequences, problems, and PATTERSON BD, PL MESERVE, and BK LANG. 1990. management considerations. International Wildlife Quantitative habitat assessment of small mammals Management Conference pp. 406-409. along and elevational transect in temperate rainforests BRANDON K, KH REDFORD, and SE SANDERSON. of Chile. Journal of Mammalogy 71:620-633. 1998. Parks in peril: people, politics, and protected PEARSON OP 1983. Characteristics of a mammalian areas. Island Press, Washington, DC, USA 519 pp. fauna from forests in Patagonia, southern Argen- BRATTON SP. 1974. The effect of the European wild tina. Journal of Mammalogy 64:476-492. boar (Sus scrofa) on the high elevation vernal flora 226 Mastozoología Neotropical, 12(2):217-226, Mendoza, 2005 J. D. Shepherd and R. S. Ditgen www.cricyt.edu.ar/mn.htm
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