Horn, Scott, James L. Hanula, Michael D. Ulyshen, and John C. Kilgo. 2005. Abundance of green tree frogs and insects in artificial canopy gaps in a bottomland hardwood forest. Am. Midl. Nat. 153:321-326. Abstract: We found more green tree frogs (Hyla cinerea) in canopy gaps than in closed canopy forest. Of the 331 green tree frogs observed, 88% were in canopy gaps. Likewise, higher numbers and biomasses of insects were captured in the open gap habitat. Flies were the most commonly collected insect group accounting for 54% of the total capture. These data suggest that one reason green tree frogs were more abundant in canopy gaps was the increased availability of prey and that small canopy gaps provide early successional habitats that are beneficial to green tree frog populations

JAMES L. HANULA

JOHN C. KILGO

MICHAEL D. ULYSHEN

SCOTT HORN

Crossref

DE-AI09-00SR22188                      JOURNAL ARTICLE                       2005                     05-07-P       
1999; Moorman and Guynn, 2001), more than closed canopy forest. It is likely that 
populations of reptiles and amphibians are affected by groupselection harvests as well. 
Amphibians are an important part of most southeastern communities (Bennett et at., 1980) 
and are widely considered to be good indicators of environmental health and function 
(Phelps and Lancia, 1995). Because of their importance within ecosystems, seveml studies ' 
have sought to determine how forest management affects their populations. Gearcutting is 
a major Pactor altering herpetofaunal communities (Enge ar~d Marion, 1986; Pough et aL, 
1987; Petranka et ul., 1993; Phelps and Lancia, 19951, b u ~  Greenberg (2001) found that gaps 
created by wind disturbance in the southern Appalachians had litde effect on terrestrial 
amphibian abundance relative to the surrounding intact forest. 
Few studies have examined how forest management affecb species such as the green tree 
frog (Hyla cinmea) that spend little time on the ground. In onc study, Phelps and Lancia 
(1995) captured green tree frogs more frequently in clearcuts using the pipe collecuon 
method, but thcy were uncertain if their results were due to their method of trapping or to 
habitat preference. Likewise, Cromer et a!. (2002) documented that tree frog abundance was 
positively associated with the creation of artificial canopy gaps. 
Terrestrial arthropods serve as food for many amphibian and repule species, but little 
information exists on the potential interactions among forest management, arthropods 
and hylid tree frogs. The objectives of this smdy were to compare the abundance of green 
tree frogs in artificially created canopy gaps to that at similar heigha in the surrounding 
dosed canopy forest and to compare frog abundance wilh ar~hropod abundance in thc 
same habiiats. 
METHODS 
This study was conducted in 2003 at the U. S. Department of Energy @OE), Savannah 
River Site (SKS) near Aiken, South Carolina. The SRS is an 80,269 ha nuclear production 
facility loca~ed in the upper Atlantic Coastal Plain Physiographic Province (Knox and 
Sharitz, 1990). The majority of the laad on the site is forcsted and managed as a DOE 
National Environmental Research Park. The stands used in this study consisted of 75 year- 
old bottomland hardwoods approximately 120 ha in total size (KiIgo, 1997'). Common 
overstory trees within the intact forest included bald cypress (Taxodium distichurn), laurcl oak 
( Qumcus burifolia) , w<llow oak ( Q. ppkallos) , overcup oak Q. lyrala), cherrybark oak ( Q. jakata 
~ ~ 6 1 :  pagodaefolia), swamp chestnut oak (Q. michauxii), sweetgum (Lipi&mbarstyrac$f2ua), red 
maple (Acw &m) and loblolly pine (Pinw tach). The midstory consisted of red mulberry 
(Mas  rubra) , ironwood ( Carpinus camliniana) and American holly (Ilex opaca) , while the 
understory was dominated by dwarf palmetto (Sabd minor) and switchcane (Armdinaria 
gigantea). Pre-hamest basaI area of the forest was 33 rn2/ha (Pauley et al., 1996). Artificial 
canopy gaps were created by group seIection harvests in August 2000. We sampled 0.50 and 
0.26 ha gaps that consisted mainly of dwarf palmetto, switchcane, blackberries (Rubus spp.), . 
sweetgum and plume grass (E~ianthmr gigucnteus). Due to the large amount of rainfall 
received in 2003, the gaps and surrounding forest werc flooded throughout most of the year 
and were covered 14th approximately 15 cm of water when frog observations were made. 
Green tree frog abundance .was recorded in five canopy gap plots and five closed canopy ' 
forest plots in August and September 2003. Three of the canopy gap plots were 0.26 ha in 
size, while two wcre 0.50 ha in size. The area searched in the corresponding closed canopy 
forest plots was similar in size to that of the created gap and were selected randomly. T h e  -' 
disbnce between plots varied, howcver the minimum distance between canopy gaps was 
approximately 200 m. Each plot was searched for 1 man-hour and all tree frogs encoontered 
during that time were counted. Forest interior plots consisted of are= similar in size to the 
canopy gaps located approximately 50 m from each gap. Vegetation in the gaps was 1-3 rn 
tall so we only searched vegetation in the forest interior that was  in the same size range. 
Active-flying arthropods were sampled in 2001 using modified malaise traps (Canopy 
Traps, Sante Traps Inc., Lexington, Kentucky]. The traps were 2.5 m in height wih 
collection containers at the top and bottom. Each trap had a central cross-shaped barrier 
which aIlorved insect$ to enter from any direction. Arthropods entering the traps wcre 
coIlected in plastic bottles containing a NaCl and 1 % formaldehyde solution in which a drop 
' of qetergent was added to reduce surface tension. Samples were returned to the laboratory 
and stored in 70% alcohol until they could be identified. Traps were operated for one 7 
d period in the months of April, May, July and November 2001. Although we colIected insect 
data 2 y beforc the frog surveys, it is likcly that relativc insect abundance between gap and 
forest habitat was similar in 2001 and 2003. The reason for this assumption is because the 
gaps wcrc similar in their plant composition in 2001 and 2003, with the main difference 
being plant height, while the forest plots were unchanged between years. 
rkthropods were identified to order, ovendried for 48 h at 40 C, and weighed to estimate 
biomass. A paired k-test was used to determine if h e  numbers of insects or tree frogs differed 
between gap and forest plots. 
R~surrrs AND DISCUSSION 
Of 331 green tree frogs observed, more were found in the gaps (mean % SE = 58.4 2 18.5) 
comparcd to closed canopy forest (mean 4 SE = '9.8 -t 2.5) (P = 0.027). Greater than 88% of 
the total number of frogs observed were in gaps where they occurred on dwarf palmetto, 
switchc~ne, plume grass and sedges while frogs in the forest interior were almost exclusively 
on dwarf palmetto. This may be attributed to dwarf palmetto being the dominant understory 
plant present in closed canopy forests. Only 2.4% of the frogs observed were adults. We 
collected 7628 insects from the 10 plots, with significantly higher numbers (P = 0.009) 
collected from canopy gaps than from the forest interior {Table I ) .  Greater than 86% of the 
insecb capturcd and 82% of the biomass wcrc from artificially created canopy gaps. Diptera, 
Lepidoptera, Coleoptera and Hymenoptera, made up >75% and 80% of the total number 
of insects and biomass, respectively. hi general, the mean number of each insect order 
captured was higher in canopy gaps (Table 1) than in forests, but Diptera (P = 0.014), 
Hymenoptera (P = 0.0151, and Coleoptera (P = 0.080) were significantly more abundant in 
gaps and Lepidotera biomass {mainIy mochs) was higher in gaps (P = 0.025). 
The plant community response to disturbance influences many aspects of h e  ecosystem 
{Runkle, l998), and is particularly important in determining the insect community's 
diversity and distribution (Waltz and Whitman, 1997). The gaps created in this study had an 
abundance of early-successional vegetation and were dr~matically different than the 
undisturbed forest. The herbaceous vegetation in the gaps was more structurally complex 
compared to the closed canopy forest (personal observation) and this may explain why we . 
saw increases in insect abundance. 
Hylid tree frogs are generally considered to be indiscriminate predators (Oplinger, 1976; 
Clark, 1.9'74;.Johnson and Christjansen, 19'76; Labanick, 1976; Tyler and Hoestenbach, 1979). 
' Holbrook (1842) stated that green tree frogs fed on flies and Haber (1926) found them to 
commonly prey upon flies, beetles, anb and moths. Freed (1982) used stomach pumping to 
show that larva1 moths and beetles were the two most common prey selected in the field, while 
laboratory studies proved that flies in the genus Mwca were preferred over other available 
prey. Taken together, these studies suggest that the availability and abundance of various prey 
types determine the diet of green tree frogs, not preference for a particular type or species 
(Oplinger, 1967; Johnson and Christiansen, 1976; Labanick, 1976). 
TABLE I.-Mean number and biomass (g) of the four most abundan~ orders of insects collected and 
the mean number of insects captured per plot in canopy gaps (n = 5) and interior borlomland 
hardwood forest (n = 5 )  
Gap Forest 
Order Mean No. T SF. Mean WL. + sr Mcan No. Z 3: Mean Wt. Z SE 
Diptera 768.2 2 226.5*" 0.24 2 0.094 54.4 2 12.3 0.15 % 0.07 
Lepidopiera 106.8 2 21.7 0.21 2 0.066"" 63.0 2 16.3 0.02 % 0.Ol 
Coleoptera 85.6 ? 23.7* 0.39 2 0.19' 97.0 r 6.2 0.07 r 0.02 
Hymenoptera 45.6 ? 9.2*-* 0.13 2 0.0543 15.0 L 3.9 0.03 2 0.02 
Mean (a11 orders) 1121 + 266.5** 1.26 2 0.51" 204.6 5 31.6 0.26 ? 0.09 
'denotes a significant difieference {P < 0.10) 
"*dcnotcs a significant difference (I' < 0.05) behveen gap and forest based on a paired t-test 
The distribution and abundance of food is one of the most important factors influencing 
the evolution of adaplauons among species (Krebs and Davies, 1987). Studies have suggested 
that increased food resources are correlated with higher densities of birds (Blake and 
Hoppes, 1986). However, little or no information exists on how amphibians, particularly 
hylid trce frogs, respond to increased food availability. It seems that locally abundant food 
: would influence the distribution and abundance of green tree frogs. Our study shows h a t  
green tree frogs were more abundant in gaps where they had five to six times more food 
available compared to forested plots located only 50 m away. 
Presently, clearcutting is the most common method for regenerating bottomland 
hardwoods and provides habitat for opportunistic species that respond well to ephemeral 
habitats (Costello cL aL, 2000). However, some species only remain if certain attributes are 
relained in the surrounding forest, as in groupselection harvests. Cromer et aE. (2002) found 
that gap creation likely benefits some groups like tree frogs, while reducing the suitability of 
habitat for others like salamanders. Phelps and Eancia (1995) and Enge and Marion (1986) 
concluded that smaller forest clearings would benefit the diversity of local herpetofauna. 
Small-scale disturbances such as canopy gaps provide low-growing vegetative structure for 
insects and green tree frogs, while leaving the surrounding forest uncompromised. Bury and 
Corn (1988) found reptiles to be more common in clearcuts due to an increase in ambicnt 
temperature, a finding similar to that of Phelps and Lancia (1995) in South Carolina. 
Likewise, Greenberg (2001) suggested that increased light lcvels in wind-created canopy gaps 
positively influenced reptilc abundance. However, increased prey mailability is also likely to 
havc a strong influence on the distribution and abundance of reptiles and amphibians. Most 
likely, a combination of factors such as increased prey availability, moisture, light and 
temperature contribute to their habitat choice. 
Acknowkdgments.-This research w a s  supported by [he National Research Inilialive Compctitivc 
Grrlntq Program of the USDA Cooperauvc Statc Rcsearch Education and Extension Service (CSIREES 
Grant No. 00-35101-9307). Wc thank the U.S. Forest Service-Savannah River and U.S. Department of 
Energy for access and logistical support throughout the duration of  this project. Mention of product 
names does not constitute endorsement by the U.S. Government. 
BEAUDRY, S.  L. C. DUCAESNL AND B. COTE. 1997. Short-term efCecw of three forestry practices on carabid 
assemblages in a jack pinc forest. Can. J. FM: h., 27:2065-2071. 
BENNETT, S. H., J. W. GIBBONS AND J. GLAWIUE. 1980. Terrestrial activity, abundauce, and diversiq of 
amphibians in differently managed forest types. Am. Mid!. Nuk., 103:412416. 
RIAKE,J. G. AKD I$'. G. HOPPES. 1986. lnfluence of resource abundance on use of treefall gaps by Mrds i11 
an isolated woodlot. Auk, 103:32&340. 
Beouw, N. V. L. 1985. Gap-phaw regeneration in a tropical forcst. EFology, 66:682-687. 
BURY, R. B. AVD F. S. CORN. 1988. Douglas-fir forest in the Oregon and Washington Cascadcs: relaiion of 
the herpetofauna to stand age and moisture. In: R. C. Szaro, K. E. Sefverson and D. R. Fatton 
I (eds.). Management of amphibians, repiiles and smalI mammds in Noxth America. USDA 
Forest Service, Gen. Tech. Rep. RM-166. 
CI.W, R. D. 1974. Food habits of toads, genus Bufo (Amphibia: Bufonidae). Am. MidL Mat., 91:140-147. 
CLZTTERRUGK, W. K AKD J. S. MEADOWS. 1993. Rcgcnerating oaks in the bottomlands. fn: D. L. Loftis and 
C. E. McGee (eds.). Oak regeneration: serious practical recommendations. U.S. For. 
Serv. Gen. Tech. Rep. GTR SE84. 
CONNELL, J. H. 1978. Diversity in tropical rain forests and coral reefs. Science, 199:1302-1309. 
C~SLWLO, C. A., M. YA~LLWKI, P.J. PEKINS, W. R. LEAK AND C. X). NEWUS. 2000. Songbird response to group 
selection harvests and clearcuts in a Nerv Hampshire northern hardwood forests. For. EtoI. 
Manage., 127:41-54. 
CROMER, . B., J. D. LANW\~ AND H. H. HANUN. 2002. Herpetofaunal response to gap and skidder-n~t 
weiland creation in a .southern bottomland hardwood Corest. l:w Scb, 48:407-415. 
DAHL, T. E. 1990. Wedand losses in the United States 1780's to 1980's. U.S. Dept. of Inierior, USFWS. 
M'ashington, D.C. 21 p. 
DENSLOW, J. L. 1980. Gap partitioning among tropical rain forest trees. Bzokrqfl., 1247-55. 
ENGE, g. M. AND h! k ~ u O Y .  1986. Effects of clearcutting and site preparation on herpemfauna of 
a north Florida flahvoods. Fur. Ecocol. ~Wunnge., 14: 177-1 92. 
Fi~eu ,  A. N. 1982. A treefrogs menu: selection for an evcning's meal. Oerohg-i, 5320-26. 
GOW, L. E., B. D. KEEWXD, S.  M O P ~ R ,  S. L. KING AND K.J. JOHNSON. 1996. h: M. Flynn (ed.) . Effect? of 
canopy gap dynamics on anhropod abundance in a bottomland forest in northeast Arkansas. 
Proceedings of ~e southern forested wetlands ecolog and lnanagcmenl conference. CIemson, 
South Carolina. 
GMENBERG, C. H. 2001. Response of reptile and amphibian communities to canopy gaps created by wind 
disturbance in the southern Appalachians. Fox Ecok ~Wunoge., 148:135-144. 
G U ~ I N ,  J. M. 1996. The role of uneven-aged silviculture in the contexi of ecosystem management. Wes. 
J. App. Fur, 11:412. 
Hhne~, V. R. 1926. The food of the Carolina tree frog, HyIa cinerea. J. Camp. Psych, 6(2). 
HAXTSH~RK, G. S. 1978. Treef-ails and tropical forest dynamics. liar P. B. Tomlinson and M. H. Zimrnennan 
(eds.). Tropical foresls as living systems. Cambridge University Press, Cambridge, England. 
HELIOJA, J. M. KOMJLA AND J. NILMEM. 2001. Distribution of carabid beetles {Coleoptera, Carabidae) 
across a boreal forest clearcut ecotone. Cons. BzoL, 15:370-377. 
HOLBROO~J.  E. 1842. Norih American Herpetology, Vol. TV. Reprinted 1976 for The Society for the 
Stndy of Amphibians and Rep~les,  Idlaca, Ncw York. 138 p. 
JOHNSON, B. K. MUJ. L. CHIUSTIANSEN. 1976. The food and food habits of BIanchard's cricket frog, Am% 
cr#tans blanchrsrdi (Amphibia, Anura, Bylidae), in Iowa. J. H@e!oZ., 10:65-74. 
KLLGo,J. C. 1997. Establishment report: the gap project. USDA Foresi Service, Savannah river Institute. 
43 p. 
K. V. MIUER AND W. F. SMITH. 1999. EKects of groupselection timber harvests in bottomland 
ha rd~oods  on  fall migrant birds. J. Field h i t h o L ,  70:404413. 
KNOX, J. N. AKD R. R. SMZ. 1990. Endangered, threatened, and rare vascular flora of thc Savannah 
River Site. Savannah River Site National Environmental Research Park Program, Savannah 
River Ecology Lab, Aiken, SC, USA. 
K o r w y  M., J. KUKKONEN AND J. NIEMEIA. 2002. Boreal carabid beetle (Coleoptera: Carabidae) 
assemblages along the clearcut originated succession gradient. Bin. and Corns., 11:1269-1288. 
KREBS, J. R. m n  N. B. D.4wm. 198'7. An introduction to behavioral ecolob~, 2nd ed. Sinauer Assoc., 
Sunderland, Massachusetts. 
L,IBANI[:K, G. M. 1976. Prey availability, consumption and selection in thc crickct frog, An&c crqbitum. 
J. H q t o L ,  10:293-298. 
LEVEY, D. J. 1988. Tropical wet forest treefall gaps and distributions of understory birds and plants. EcuL, 
69:107&1079. 
MARTTN, T. E. ,wnJ. R. EGIRR. 1986. Patch utili~ation by migmting birds: resource oriented? h i s  Scan., .' 
17:165-174. 
M o o w ,  C.  E. AND D. C. GUYNN. 2001. Effects of groupselection opening size on breeding bird habitat - 
use in a bottomland forest. KcoL AfipE., 11:1680-1691. 
OPUWGER, C. S. 1976. Food habits and feeding activity of recently transformed and adult Hyla n u c z j h  ' 
nucijm Htrpeiol., 23209-217. 
PAUL& E. F., B. S. COLLINS AND MT. P. SMITH. 1906. Early establishment of cherrybark oak in bottomIand 
hardwood gaps: effects of seed predation, gap size, herbivory, and competition. In: K. M. F l y n  
(ed.). Proceedings of the southern forested wetlands ecoloby and management conference. 
Clernson Univ., Clemsou, ~ o h t h  Carolina. 332 p. 
P~.mhr~n, J. \\FA, M. E. E L ~ R ~ G E  AND K E. HALEY. 1998.  effect^ of timber harvesting on southern 
Applachians salamanders. Cons. BioL, 7:36%370. 
PHELPS, 1. P. ANU R. A. LANCIA. 1995. Effects of a clearcut on the herpetofauna of a South Carolina 
bottomland swamp. BrimQ., 223145.  
Pou~r-I, F. H., E. M. SMITII, D. H. RI-IO~ES AND A. C O L ~ O .  1987. The abundance of salamanders in forest 
stands with different histories of dis~urbance. fir EcoL Manup., 201-9. 
RUNU, J. k 1998. Changcs in southern AppaIachian canopy tree gaps sampled thrice. EcoE., 79: 
1768-1 780. 
SCHE~ISKE, D. W. AND N. BROKA~!~. 1981. Treefalls and the distribution of understory birds in a tropical 
forest. EcoL, 62938-945. 
STIURF., D  J. AND D. L. PHILLIPS. 1991. Patch s i ~ e  of fores~ openings and arthropod populations. Oecologza, 
86:325-334 
so us^, N7. P 1984. Thc role of disturbance in natural communities. Ann. h. Ecol. Syst., 15353-391. 
Teobf~so~, L. C. AND R. T. ALLEN. 1093. Site preparation affects ground beetles in a clearcut bottomland 
hardwood forest in southeastern Arkansas. In: J. C. Brissette (ed.). Proceedings of the seventh 
biennial southern silvicultural research conference. Gen. Tech. Rep. SO-93. New Orleans, 
Louisiana. 
TYLER, J. D. AND W. n. HOESTEYBACH. 1979. Differences in food of bullfrogs (Ram catesaiunana) from pond 
and stream habitats in southrvestern Oklahoma. S W  N d ,  24:9.5-38. 
UTII., C. n N n  P. G. MUWI-N. 1981. Composition, structure, and regenerahn of liera firme forest in the 
Amamn k i n  06Venezuela. %p. EoL, 22:219-237. 
USDA Foa~sr SERVICE. 1988. The South's fonrrh forest: altcrnativcs for the futurc. U.S. For. Sen?, For. 
Rcs. Rep. 24. 
WFTERS, B.B. .wn E. W. STILES. 1996. Effect of canopy gaps and flower patch size on poIlinator visitation 
of Impatiens capensis. Ball. T m  Bot., 1233184-188. 
M~ALT-L, A. hq. W,U T. G. 1 4 7 ~ r r h w ~ .  1997. Plant developmcnt f l e a s  arthropod communities: opposing 
impacts of species removal. EcoEogy, 78:2 133-2144. 
~VARRINER, M. D., T. E. NE~TKER, T. D. L r ~ ~ ~ ~ ~ ~ . ~  AND J. S. MFMOWS. 2002. In: K W. Outcalt (ed.). 
Proceedings of the e leve~th  biennial southern silvicultt~ral research conference. USDA Forest , 
Service Gen. Tech. Rep. SM-48. 
WILSON, M. F., E. A. PERTER  AN^ R. S. C O N D I ~  1982. Avian frugivore activity in relation to forest light gaps. 
Car. J. Sci., 18:1-6. 
W U ~ E ~ E ,  J. M., JR., A. DMZ, I. VKWZQULUEZ AKD R. SCI-IORRON. 1987. Forest openings and the distribution 
of ~mde~story birds in a Puerto Rican rainforest. Wils. Bull., 9922-37. 


English

Abundance of Green Tree Frogs and Insects in Artificial Canopy Gaps in a Bottomland Hardwood Forest

Horn, Scott

Hanula, James L.

Ulyshen, Michael D.

Kilgo, John C.

UNT Digital Library

Abundance of green tree frogs and insects in artificial canopy gaps in a bottomland hardwood forest.

ABSTRACT - We found more green tree frogs ( Hyla cinerea) n canopv gaps than in closed canopy forest. Of the 331 green tree frogs observed, 88% were in canopv gaps. Likewise, higher numbers and biomasses of insects were captured in the open gap habitat Flies were the most commonlv collected insect group accounting for 54% of the total capture. These data suggest that one reason green tree frogs were more abundant in canopy gaps was the increased availability of prey and that small canopy gaps provide early successional habitats that are beneficial to green tree frog populations

Hanula, James, L.

Kilgo, John, C.

Abundance of Green Tree Frogs and Insects in Artificial Canopy Gaps in a Bottomland Hardwood Forest.

http://digital.library.unt.edu/ark:/67531/metadc788000/

Abundance of Green Tree Frogs and Insects in Artificial Canopy Gaps in a Bottomland Hardwood Forest

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