Comparison of Terrestrial Invertebrate Biomass and Richness in Young Mixed Red Alder-Conifer,Young Conifer, and Old Conifer Stands of Southeast Alaska

Mark E. Schultz', USDA Forest Service, Alaska Region, State and Private Forestry, Forest Health Protection. 2770 Sherwood Lane, Juneau, Alaska 99801 and Toni L. De Santo, USDA Forest Service, Pacific Northwest Research Station, USDA Forest Service, 2770 Sherwood Lane, Juneau, Alaska, 99801

Abstract Coniferous stands that regenerate following clearcutting in southeast Alaska can be characterized by the amount of soil disturbance during logging. There are indications that red alder in mixed stands mitigates some of the negative effects of clearcutting. We compared invmebrate biomass in four stands each of (1) young conifers, (2) young mixed alder and conifer, and (3) old conifers to dctcrtmnc if aldcr was hcncfic~alto invcrtchratcs. Collcmhola, thcn Aranac taxa wcrc nlow ahundant hut Cdcnptcra had thc . greatest invertebrate biomass on boles of red alder, Sitka spruce, or westem hemlock. Diptera taxa were the most abundant in flight traps in young mixcd aldcr and wnifcr stands. Pmcnptea taxa WMC thc most ahundant invcrtchratcs collcctcd from any foliage. Some rarer invertebrate families were unique to one or another of the tree species. Crawling invertebrate species richness was greatest on red alder and in young mixed alder and conifer stands. The greatest biomass of crawling invertebrates occurred on Sitka spruce boles. Old stands had about the same invertebrate biomass as mixed alder or conifer young stands. Hying invertebrate biomass and species richness was greatest in young stands of mixed alder and conifer. miceas many invertebrate species were found on westean hemlock or Sitka spruce foliage as on red alder foliage but invertebrate species richness was greatest on red alder. fnvertebrate biomass on red alda foliage was 20-100 times greater than on the equivalent weight of Sitka spluce or WcStm hcmlock foliagc. Rcd aldcr significantly contrihutcs invcrtchratc spccics richncss and hiomass to young forcst stan& of southeast Alaska.

Introduction 1994, Ruggiero et al. 1991) and regenerating There is incming interest in developing new stand clearcuts (Morrison 1981, Santillo et al. 1989). management strategies to maintain or enhance The role of deciduous trees and their influence on biodiversity and assure long-term sustainability of invertebrate populations is not well understood forest, wildlife, and aquatic resources. Abundance (McComb 1994). particularly in southeast Alaska. of terrestrial invertebrates is closely associated Richness of invertebrate taxa is often hard to with forest vegetation and some riparian plant quantify and compare between stand types be- species supply more invertebrates to streams than cause richness depends upon sample size (Gotelli others (Mason and Macdonald 1982). Increased and Colwell, 2001). Physical factors such as soil invertebrate production can increase vertebrate moisture and temperature have a large effect on abundance and diversity by providing more food invertebrate biomass and species richness; aspect for birds, bats, small mammals, and fish. and size of clear-cuts can affect the presence of soil invertebrates (Marra and Edmonds 1998). Little is known about interactions among plant Schowalter and Ganio (1998) found that tree spe- species composition, invertebrate abundance, and cies and canopy height were important factors in vertebrate abundance. Bird abundance has been the variation and biomass of invertebrate taxa. found to be low in young stands of dense conifers (Schwab 1979, Easton and Martin 1998) and a In Alaska, red alder (Alnus rubra Bong.) is positive association between bird abundance and the most frequently associated deciduous tree the density of live deciduous trees has been found with Sitka spruce (Picea sitchensis Bong. Carr.), in young forests (Huff and Raley 1991, McComb western hemlock (Tsuga hterophylla Raf. Sarg.), and westem redcedar (Thuja plicata Donn ex D. 'Author to whom correspondence should be addressed. Email: Don). Red alder generally occurs near sea level as mschultz01 @fs.fed.us. a shade intolerant tree with rapid juvenile height

120 Northwest Science, Vol. 80, No. 2,2006

0 2006 by the Srmhwrst ScicutidF Asrociaaw. AU rqh~mmed growth (Harrington 1990). It occurs as a lowland in four mixed alder and conifer young stands species along the northern Pacific Coast. and its (YA), four young conifer stands (YC), and four range extends from southern California to south- old conifer stands (OC).Our hypothesis was that east Alaska. Red alder grows in zones receiving terrestrial invertebrate biomass and richness is from 40 to 560 cm of precipitation annually and greater in YA than in YC or OC. is limited by winter temperature (Harrington et al. 1994). It grows in a wide range of soils, from Methods welldrained gravels or sands to clays and organic soils, Red alder can tolerate poor drainage and Study Area some flooding during the growing seas&. The To study the influence of red alder on invertebrate most productive alder stands are found on deep communities, we selected study areas in the alluvial soils in river and scream flood plains. Maybeso, Harris, and Polk watersheds, Prince Some productive stands can be found on upland of Wales Island, Alaska (figure 1). Maybeso and sites on residual or colluvial soils. Harris watersheds were chosen because they have Red alder is commonly found along beaches large areas of relatively uniform stand age and and streams, on snow avalanche and landslide site productivity with a wide range of red alder, tracks, and as a pioneer species with Sitka spruce, western hemlock, and Sitka spruce mixtures. black cottonwood (Populus trichocalpa Torr. and Polk watershed was chosen because it had Gray) and willows (Salix spp,) on exposed min- older trees and stands. Mean annual temperature eral soils (Harris and Farr 1974; Ruth and Harris is 10°C and mean annual precipitation is 280 cm. 1979). Logging has increased the amount of red The basins are U-shaped glacial valleys covered alder in forests of southeast Alaska, particularly in by varying thickness of glacial till (Gomi et al. upland areas with heavy soil disturbance. Young 2003). Dominant forest vegetation includes red alder grows rapidly but growth slows after western hemlock, Sitka spruce, western red ce- the juvenile stage. Habitat quality for some small dar, and red alder; however, riparian vegetation mammals in even-aged, mixed red alder and is highly influenced by past mass movement conifer stands may be equal to that of old forests regimes such as landslides and debris flows. (Hanley 19%). Forty year old mixed red alder and Sites in the Maybeso and Harris watersheds conifer stands have both species-rich and highly were clearcut in the 1950's and experienced productive understory vegetation with biomass similar to that of old stands of the region (Hanley significant landslides and debris flows in 1962 and 1979. Basal area in young stands was 63-8 1 and Hoe1 1996; Hanley and Barnard 1998). In m2/ha.The sites were dominated by young alder the absence of repeated disturbance red alder is in the riparian zones of headwater streams. The replaced by longer-lived conifers, which begin to Polk watershed, where the old conifer sites were overtop red alder within a few decades (Hanington located was never logged. The old stands were 1990; Orlikowska et al. 2004). Canopy closure approximately 300-400 years old and had a basal of coniferous forests generally occurs 25 to 35 area of 145- 185 m2/ha. years after cutting followed by a nearly complete elimination of understory vegetation for up to Four YA, four YC, and four OC stands were 100 years (Alaback 1982; Tappeiner & Alaback chosen. Sampling was completed from May 1989). However, the dense, uniform, even-aged through September, 2000 and 2001 when inver- conifer stands quickly develop broadly negative tebrates were developing and active. consequences for wildlife and fish (Wallrno and Schoen 1980; Schoen et al. 1981; Thedinga et Crawling Invertebrates al. 1989; Hanley 1993; Dellasala et al. 1996). Passive sampling of invertebrates was done on Sitka Little is known about the change in invertebrate spruce, western hemlock, and red alder trees boles. communities as stands progress from mixed One trap for each tree was installed around the bole alder-conifer, to young pure conifer, to mature of three trees of each tree species per site (Hanula conifer stands. and New 19%). Traps were located 1.5-2 meters As part of a larger study on disturbance history, from the ground and collected invertebrates in a stand structure, and vertebrate and invertebrate detachable cup that contained 70 percent ethanol. communities we compared terrestrial invertebrates Invertebrates, normally phototropic, crawled up

Terrestrial Invertebrates on Alders and Conifers 121 Figure 1. Location of study sites on Prince of Wales Island, southeast Alaska. the tree into the trap and fell into the collecting were located in the middle of each stand, more cup. Invertebratescollected in traps were measured than 10 meters from a stream, and where there for length (Hodar 1996). and identified to species were no obstructionswithin 4 meters of the ground or separated into unidentified species. and 5 meters distance. A sample was collected In 2000, there were 14to 15 continuous seven- after the first 24 hours and another sample after day-sample periods for each of the eight young the second 24 hour period, then the traps were stands. The young-stand crawling-invertebrate dismantled. Invertebrates were dry-trapped in a biomass was analyzed on 704 of 845 samples. Not container at the top of each trap, and killed with all stands were sampled in April, and there was bear a small section of Insect GuardTM(Dichlorvos; damage to some of the traps in May and September DDVP; 2,2-Dichlorovinyl dimethyl phosphate). resulting in incomplete samples. However, all 845 Invertebrates were washed from the container samples were used for species richness analyses. and placed into a labeled sample container using None of the OC stands we= sampled for crawl- 70 percent ethanol. There was one trap per site ing invertebrates in 2000. In 200 1, 19 1 YA and and each site was sampled weekly in 2000 and YC samples add 71 OC samples were used for biweekly in 2001 beginning in May and continu- biomass and species richness analyses. ing through September. In 2000,266 YA, YC, and OC samples were Flying Invertebrates taken. In 2001,144 samples were taken. All 400 Malaise traps were set up for 48 hours to collect samples fromboth years were used for invertebrate flying and a few crawling invertebrates. Traps biomass and species richness analyses.

122 Schultz and De Santo Foliage Invertebrates 1.4m height, for each tree species. This value was multiplied by the number of boles per hectare to Once a week from May through September, 2000, estimate biomass per day per hectare for each lower crown branch tips from three each of red invertebrate taxon on each tree species. alder, Sitka spruce, and western hemlock were sampled, in all YA and YC stands. No samples Flight trap invertebrate numbers were not ad- were taken in 2001. Approximately 50 cm of justed by stand area sampled, because there was branch length was clipped from each tree. Fewer no way to determine what area was sampled by red alder branches were sampled than either Sitka Malaise traps. Flight trap catch was calculated spruce or western hemlock branches. OC stands as mg per day of biomass for each invertebrate were not sampled because it was hard to find taxon. lower branches that could be sampled, especially Flying and crawling invertebrate trapped bio- late in the sampling process. Invertebrates were mass was averaged across collection date or across shaken from branches onto a white bag so that tree species and collection date. Analysis of vari- they could be seen and collected, dispensed into ance (SASm)was used to compare the invertebrate a jar containing 70 percent ethanol, measured for biomass of the three stand types, the three tree length, and identified to the lowest taxonomic species, and presence of alder. rank possible. Invertebrate species richness was analyzed To determine invertebrate biomass per leaf across tree species and stand types. Chi-square biomass for red alder (124 samples) leaves were analyses of invertebrate numbers within each stripped from each 50 cm branch sample into a invertebrate taxon were used to determine dif- labeled paper bag, oven dried, and weighed. For ferences between tree species and between all Sitka spruce and western hemlock the length of stand types. all primary and secondary branches was recorded. There were too few inver2ebrates collected from Needles were plucked from branches, dried, foliage to do a statistical analysis between stand and weighed. The average oven-dry weight of 5 types or tree species. However, an invertebrate samples of 100 needles was used to determine species richness analysis was made. the mg of invertebrates per 100 g of needles. Thd dry weight of needles for each branch sample was Results determined by multiplying the average needle dry weight (6.72 mg for Sitka spruce and 1.36 Crawling Invertebrates mg for western hemlock) by the average number There was a significant difference, 2000 and 200 1 of needles per cm of twig reported by Werner data combined, in invertebrate biomass (mgldayl (1969) (20.27 for Sitka spruce and 12.40 for hectare) between YA andYC but not between YA western hemlock), and multiplying that product or YC and OC (My,= 42.6,and M, = 62.4 M, by the cm of branch length sampled to estimate = 61.2, SE,= 4.3, SEy,= 8.9, SE,= 12.2, ), foliage biomass per branch. In this way, the ratio and between Sitka spruce and western hemlock of invertebrate biomass to foliage biomass was (M,=52.16, M,=63.66, M,,,,=37.33, SE,=9.97, determined for each sample. SE,,=5.97, SE,,=7.72), and between young stands with and without red alder (MAdm=42.65, Data Analysis %,=62.28, SE,,=L1.27, SLz8.00). Stands For crawling invertebrates caught in bole traps, without red alder had the greatest mean inver- mean tree diameter per hectare was determined by tebrate biomass. Sitka spruce had the greatest measuring the diameter at 1.4 m height of all plot mean vertebrate biomass followed by red alder trees. Bole trap catch biomass was calculated as and western hemlock. mg of invertebrates per cm of tree bole circumfer- In 2000 and 2001, invertebrates with the greatest ence per day. Formulas based on body length for aggregate biomass, all trap records combined, were each invertebrate taxonomic order (H6dar 1996) insects (62%) (Coleoptera 41%), aranae (25%), were used to calculate invertebrate biomass. For Collembola (3%), and then Acari (1%). The most each invertebrate taxon a standardized biomass numerous invertebrates were Collembola (67%), was estimated by multiplying biomass per cm Acad (18%), Insecta (12%), and then Aranae (2%). of tree bole by average bole circumference, at Red alder had disproportionately more crawling

Terrestrial Invertebrates on Alders and Conifers 123 haeand fewer Coleoptera, Collembola. and Flying Invertebrates Acari; westem hemlock had disproportionately more Collembola and Acari and fewer coleoptera; Flight traps caught different invertebrates than Sitka spruce had disproportionally more Coleop bole traps. When all stand types are compared tera (Table 1). A total of 6 1,118 individuals were there was a significant difference in biomass classified into 290 invertebrate ma (Table 2) by (mglday) between YA and YC and between YC stand type. and OC (M, = 18.7, M,= 11.5, M,= 16.8, Red alder had more unique invertebrate species, SE,= 1.39, SE,,= 1.10, SEW = 1.62,) and a per 100 samples, than Sitka spruce or western significant difference between the presence or hemlock (Table 3). More unique families of inver- absence of red alder w-=18.67, KaAl,=14.2 1, tebrates occurred on western hemlock tree boles, SEAk=1.39, ShoMk=l.Ol),but not for day-of- followed by Sitka spruce and red alder (19,16, and collection(M, ,=16.39,% z=14.90,S~yI=1.20, 10 families, respectively). The Shannon-Weiner SE =I. 14).$~stands hadthe greatest mean in- species richness index for YA stands (4.683) was veggrate biomass, followed by OC stands. Stands slightly greater than for YC stands (4.649) and with red alder had a pater mean invertebrate much greater than for OC stands (=0.093). biomass than stands without red alder.

TABLE 1. Number of the most prevalent crawling inveaebrates within each tree-species invertebrate-family (group) category caught in stem traps (listed when more than 100 caught) in 2000 and 2001. Italic numbers in prenthesis ore less than, and bold-italic numbers more Uurn, the expected number if taxa were evedy distributed among tree species (Chi-square analysis).

K€n 31IYB WeSZem Class-Subclass (hda Family (Group) Alder SP~ Hemlock lbd -- - - - Number of Samples 259 594 593 1446 Entognatha Collembola Sminthuridae 1413 (6705) 6688 14806 Tmoceridae 1371 (4646) 6338 12355 Entomobryidae (319) 3084 3263 6666 Isotomidae 929 2052 (1219) 4200 Hypogastruridae (241) 1752 1456 3449 All 4 77'3 lR 245 18 9M 41& Arachnids Acari Cephwidae 527 (1 924) 2003 4454 Brown type (330) 1689 1707 3725 Pteromorph type 93 242 (180) 515 All 1197 4850 4804 10,851 Agelenidae 47 (60) 67 174 Linyphiidae I8 63 76 157 Pseudoscorpion 32 58 55 145 Tetragnathidae 24 51 63 138 All 238 537 585 1,360 All 1435 5387 5389 1u Coleoptera Scolytidae (301 31 01 (124) 3255 Nitidulidae (40) 421 (167) 628 Rhizophegidae 22 201 (58) 28 1 Staphylinidae 51 (49) (45) 145 Detmestidae (0) 80 61 141 All 191 3972 565 4,728 Microco'yphia All 19 767 542 1,328 Diptera All I 357 343 846 Homoptera All 116 25 1 147 5 14 All 518 551 1 1755 7784

124 Schultz and De Santo TABLE 2: Number of stem-trap samples where each taxon occurred by stand type: young alder (YA), young conifer (Yo, and old cwifer (OC) (2000 and 2001 data). 4@ss Subclass Puf%r 5.dY Stand lkpe. Genus YA YC OC Arachnia Acid Brachypilina unknown Liacam 15 14 Cipedia Gamasidae Unknown Desmwomata Unknown Euptemtegaeus Unknown unknown AraDae Araneomorphae Agelenidae Cryphueca Wadores Dictynidae Dictyrn Linyphiidae Erigone Linyphantes Pim Theridiidae Tkeridwn U?&wwn Unknown Unknown Pseudoscorpionidae Unknown Entognatha Cdlembola Entomobryidae Unknown Hypogastruridae UnRnown Lsotornidae Entognatha Unknown Sminthuridae Unknown Tomoceridae unknown Unknown Unknmm Insecta Coleoptera Cmthsridae Unknown Cucujoidea/Nitidulidae UnRnawn Curculionidae Sreremniu.~ Unknown

Terrestrial Invertebrates on Alders and Conifers 125 TABLE 2: Continued.

MonotomideelRhizophaginee unknown Scolytidae Hylurgops Trypodndrvn . unknavn Staphylinidae Halmlrzm Diptera Cecidornyiidae Thecodiplosis UnRMwn Chironomidae Unknown Ernpididae Unknown My cetophilidae Unkunvn Phoridae Unknown Sciaridae Unkunvn Tipuloidempulidae unknown

Diptera Unknown Unknown Homoptera Aphididae Uhwn Hymenoptera lchneumonldae UnRMwn Mallophaga Ricinidae UnRnawn Plecoptcra unknown Unknown Archemgnatha Micromryphia Machilidae Unknown Malacmtraca Malacostraca Unknown Unknown Unknown

By biomass and numbers (Table 4), the most brate species and unique species per 100 samples ahundant krtehrates from flight traps Were nip- than either YC or OC (Table 5). A total of 36,605 tera (46% and 9296, respectively), Hymenoptera individuals were classified inlo 220 invertebrate (27%and 396, respectively), and then LRpidoptera taxa (Table 6, the most abundant taxa), by stand (14%and 1%. respectively). YA had more inverte- type. The Shannon-Weiner species richness index

126 Schultz and De Santo TABLE 3. Number of crawling invertebrate species caught TABLE 5. Number of flying invertebrate species caught in in stem traps in years 2000 and 2001. Malaise traps in years 2000 and 2001.

Red Sitka Western Young Young Old Alder Spruce Hemlock AlderlConifer Conifer Conifer On all tree species 101 101 101 In all stand types 57 57 57 On two tree species 22 54 52 In one- other stand type 54 43 21 (target + 1 other) (target + one) Unique to a tree species 25 47 48 Unique to a stand type 44 47 12 Total invertebrate species 148 202 201 Total 155 147 90 Total @er 100 samples) 54 34 34 Total (per 100 samples) 165 138 136 Unique (per 100 samples) 9.7 7.9 7.9 Unioue her 100 sam~les) 4'7 44 18

TABLE 4. Number of flying invertebrates, within each stand, caught in Malaise traps (listed when more than 100 caught) in 2000 and 2501. Italic nwnbers in pamnthesis are less than, and bo&l-italic numbers num than, the expected number if taxa were evenly distributed among stand types (Chi-square analysis).

- -- -- y-g Young Old Family Alder Conifer Conifer Class-Subclass Order (Group) Stands Stands Stands Total Number of Samples 94 106 66 266 lnsecta Diptera Cbimmmidse (4140) 4372 1960 10472 Cecidomyiidae (2360) 2721 2377 7458 Mycetophilidae 2627 (1490) 1347 5464 Iipulidae 1783 (159) (247) 2189 Sciaridae 1016 (447) 392 1855 Psychodidae (438) (230) 686 1354 Dryomyzidae 678 421 342 1441 Phoridae 588 (253) 272 1113 All 14887 10923 8236 34041 Hymenoptera lchneumonidae 268 (153) 219 640 Liopteridae 76 74 (24) 174 All 524 341 299 1164 Coleoptera Staphylinida 249 180 98 527 tomaliiae Lepidoptera All 131 48 67 246 Hornoptera Aphididae 162 (12) (3) 177 Homoptera All 172 13 12 198 Arachnids Acari All 25 94 24 143 Total 16,14 1 11,679 8,785 36,605 for YA stands (=0.658) was greater than for YC compared to four and five per sample in July and stands (30.487) or OC stands (30.398). August. Forty-five percent of the total catch was Psocoptera, 19% Aranae, 13 % Diptera, and 5% Foliage Invertebrates Homoptera:Aphidoidea. Coleoptera, Lepidoptera, About one invertebrate was found on every thud red and Hymenoptera were only 6 % of the catch. alder branches sampled (Table 7), and an average The biomass of invertebrates caught on red of three invertebrates were found per four Sitka alder was a 20 to 100times greater than that caught spruce or westem hemlock branches sampled. The on Sitka spruce or western hemlock. About one- collections of invertebrates in June and September, half of the dipterans collected from Sitka spruce 2000 were about three invertebrates per sample or western hemlock foliage was also collected

Terrestrial Invertebrates on Alders and Conifers 127 TABLE 6. Number of Malaise-trap samples where each taxw occurred by stand type: young alder (YG-A), young conifer (YG- C), and old conifer (OG-C) (2000 and 2001 data).

Subclass QEkI EadY Genus Arachnids Acari Unknown unknown Entognatha Collembola Isotomidae Unknown ha&e Coleoptera Caatharidae Unktown Chrysomelidae Unknavn Staphylinidae Hapalaraea Diptera Anisopodidae Sylvicola UnkuMm Anthomyiidae Acridomyia unknown Anthomyzidae u- Bibonidae UnRnown Cecidomyiidae Contarinia Corinihomyia Unknown Ceratopogonidae PsilaRempia unknavn Chironomidae Chimwnurms Micmpsectm Orthocladius Rheoianytmus unknown Dixidae Unkunvn Dolichopodidae unknown Dryomyzidae Dmm Oedopamnu Unhown Empididae Anthalia Hilaria Unknown Heleomyzidae Unk?wm

128 Schultz and De Santo TABLE 6. Continued. mls . Subclass Quk Eamily Genus -YA YC OC Lauxaniidae Unknown 2 Muscidae Unhwwn 17 9 13 Mycetophilidae Exechia 4 5 Mycetophla 3 2 2 Unknown 67 73 45 Pelecorhynchidae Unknown 3 Phoridae Lccanocem 3 Perkyclocera 3 Unknown 58 Psychodidae Penncoma 3 Unknown 54 Sciacidae Unknown 63 Sciornyzidae Unknown 2 Sphaemmidae unknown 9 Syrphidae Unknown 5 Tabanidae Unknown 3 Tlpuloidea/Liddae Molophik*~ 3 . Tlpuloide~plidae Unknown 53 Trichoceridae Trickem 2 Unknown 20 uoknown Unknown 28 Xylophagidae Unknown 3 Hornoptera Aphididae Unknown 33 Unknown UnM 5 Hymenoptera Braco~dae Unknown 12 BraconidadAlysinnae Unknown 2 Charipidae Unknown 5 2 2 Diapriidae Unknown 17 10 9 Continued

Terrestrial Invertebrates on Alders and Conifers 129 TABLE 6. Continued.

lchneumonidae UltbKnvn Liopteridae unknown Platygastridae unk?wwn Proctotrupidae Unknown Sclerogibbidae unknavn Unknown uw Lepidoptera Unknown UrrAnown Neuroptera Unknown Unknown Plecoptera Nemouridae Unknown Unknown Unknmvn Psocoptera Psocidae UnRnavn Unknown Unknown

TABLE 7. Inve~tebratedata for red alder, Sitka spruce, and western hemlock foliage.

Red Sitka Western Alder Spruce Hemlock Branches Examined 124 332 355 Percent of Branch Samples with Invertebrates 34 79 75 Number of Invertebrates per meter of branch* New Species per 100 meters of branch length* 34 6.3 4.2 Average biomass(mg) per lOOg Foliage 192.4 1.7 9.9

* based on an average of 0.7,3.0, and 4.7 meters of primary and semndary branch length fordalder, Sitla spruce, and westem. hemlock, respectively. from ~d alder foliage. Sitka spruce and western to 10 different species for every 60 and 63 inver- hemlock had about the same number of unique tebrates from Sitka spruce and western hemlock, invertebrate taxa; red alder had about one-third respectively. as many. Discussion Species richness, however, was greater for red alder than for Sitka spruce or western hemlock. Red alder was an important source of invertebrate Ten different species for every 16 invertebrates diversity in the conifer stands examined in this were collected from red alder foliage, compared study. Although biomass of crawling invertebrates

130 Schultz and De Santo was greater in stands without red alder, biomass We found that old stands had a lower Shannon- of flying insects was greater in stands with red Weiner species richness number for both crawling alder, and red alder trees had more unique species and flying invertebrates than young stands with of both crawling and flying invertebrates per 100 or without red alder. samples that did either western hemlock or Sitka Managing forests in southeast Alaska for di- spruce. Stands with red alder also had the highest versity of wildlife requires careful consideration Shannon-Wiener species richness index for flying of maintaining diverse sources of food. While insects. In addition to the more complex forest old forests might offer unique assemblages of structure found in stands with red alder (Deal et invertebrates, maximizing diversity requires main- al. 2004), our results suggest that red alder may tenance of other forest types as well, including harbor an important source of invertebrate food young stands of conifers mixed with a red alder for birds. Old 300-400 year old stands in this study component. did not offer more food to insectivorousbirds than 35-40 year old young stands. Acknowledgements Relative species richness of invertebrates in southeastAlaska forested ecosystems is complex This research was made possible through funding and cannot be attributed to a single factor. In the by the USDA Forest Service, Pacific Northwest Pacific-Northwest, Schowalter and Ganto (1 998) Research Station, Wood CompatibilityInitiative, found that aidnupod communities were associated and State and Private Forestry, Forest Health Pro- quite closely with tree species. Diversity goes be- tection. We would like to thank Alison Cooney yond tree species and might reside more in the site for field. laboratory, editorial, and technical assis- factors. Progar and Schowalter (2002) found that tance. We appreciated field efforts of Dave Sperry, tree age was a factor of Shannon-Wiener diversity Amy Cunkehan, Eric Holt, Becca Cameron, and in Douglas-fir arthropod catches and precipitation Troy Seiler. We would also like to thank Amy was a factor of invertebrate biomass and diversity. Cunkelman, Hana Baker, Kelly Michaud, and Cole et al. (2003) determined that species richness Abbey Focht for there diligence in processing the of stream macro-invertebrates was not associated invertebrate samples and Melinda Lamb for the with stand age, perhaps due to inadequate sampling site map. Without the expert taxonomic help of Dr. of headwater streams. Peck and Niwa (2004) James E. Zablotny, Michigan State University, for determined that biomass and species richness of identification of the tipulid flies, and Dr. Vladimir Aranae, but not Carabidae, was greater in thinned A. Blagodemv, American Museum of Natural His- than in unthinned 16-41 year old mixed conifer tory, for identification of the mycetophliid flies, stands in western Washington. Durn (2004) found we would not be able to accurately separate many that vertebrate and invertebrate species richness of the dipteran species. We especially thank Drs. completely recovered in second growth stands Suzanne Schwab, Chris Niwa, Robert Edmonds, 39 years after deforestation, compared to what John Hard,Douglas (Sandy) Boyce, andEdHolsten existed in its former old-age condition. for their editorial changes and comments.

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