The study investigates the effect of spatial and temporal tree-fall gaps structure on spiders’ assemblage in an Atlantic forest fragmented area in Brazil. It was conducted in the Michelin Ecological Preserve-REM (Bahia), 190 ha forest remnant. Samples were collected on leaf-litter (50 × 50 cm) at five tree-fall gaps formations (<150 m<sup>2</sup>), within five adjacent primary forest and five inner edge parcels. During 16 months (between May 2009 and October 2012), 480 m<sup>2</sup> leaf-litter samples were collected, from which spiders were extracted using mini-Winkler traps. The observed and estimated richness of spider’s species was higher at the edge (p < 0.01). The habitat structures differ significantly among the three habitat types (MRPP, p < 0.01) and also during the tree-fall gaps aging gradient (MRBP, p < 0.01). There were significant differences on spiders’ species composition, comparing the three habitats (MRPP, p < 0.05). The composition of spider’s species changed as tree-fall gaps aged (MRBP, p < 0.05). We argue that the tree-fall gaps play, on a local scale, an important role in acting on the time-space distribution dynamics of spider’s species assemblages, although the time effect should still be evaluated.
Natural disturbances role in shaping the tropical forests biological communities’ structure is widely known [
The regeneration witnessed on tree-fall gaps promotes the development of primary and pioneer species, and the secondary one promotes remarkable changes on trees’ population’s dynamics, species composition and growth rate [
The tree-fall gap phase is considered the most important to determine floristic composition [
Tree-fall gaps influence the spatial and temporal distribution of plants, therefore, affect these organisms’ interactions to other animals [
Previous studies of animal related tree-fall gaps include: birds [
Spiders (Arachnida: Araneae) are among the most abundant and diverse animal group, with 44,540 species currently described in the World [
This study investigates whether tree-fall gaps show time-space scale effect on composition of spider’s assemblages species in an Atlantic forest remnant at the Michelin Ecological Reserve, Igrapiúna, Bahia, northeastern Brazil. We addressed four questions: 1) Does the habitat structure of tree-fall gap (microclimate and microhabitat) significantly differ from that found in adjacent mature forest and inner edge? 2) Does the richness and composition of tree-fall gap species significantly differ from those found in adjacent mature forest and inner edge? 3) Does the habitat structure of natural tree-fall gaps (microclimate and microhabitat) significantly change during vegetation regeneration process? 4) Does the spider’s species’ assemblage composition of tree-fall gaps significantly change throughout the regeneration process?
The study was conducted at the Ecological Reserve Michelin (REM) (13˚50'S, 39˚10'W, 90 to 383 m above sea level), situated in the city of Igrapiúna and Ituberá (state of Bahia, Brazil). It is located 18 km away from the coast in a region known as “BaixoSul”, 200 km south from the State capital city of Salvador. The 3096 ha REM area consists of a vegetation mosaic on different successional stages. Landscape id modified by different types of human disturbance, agriculture and pasture converted. And other forms of anthropogenic pressure (such as logging, hunting and exploitation of the palm). Approximately, 25% of the reserve is intended to rubber tree monoculture plantations [
The reserve contains 1800 ha of lowland evergreen hill forest distributed in three main fragments: Vila 5/Pancada Grande fragment with 625 ha, the 140 ha Luis Inácio forest, and the 550 ha Pacangê forest, which is contiguous with a 13,000 ha forest [
Eight field surveys were conducted every two months, from July 2009 to October 2010. On the northern sector of Mata Vila Cinco we defined the tree-fall gaps and forest sampling points, both in the mature forest sections. In the mature forest stretches and along the main footpath edge sample points were set. The mature forest vegetation patch presents continuous canopy ranging from 18 and 25 m. Most trees had their Diameter at breast height (DBH ) above 25 cm, moderate frequency of vines, moderate to high density of bromeliads and other epiphytes, abundant palm trees and moderately dense herbaceous vegetation [
Having selected the five tree-fall gaps, we located the edge and forest sampling points. We established five forest’s points in the stretch of primary forest, adjacent to the tree-fall gaps sampling points. We seek for points with no evidence of natural disturbance and which could characterize them as tree-fall gaps. We finally set the edge sampling points on the secondary-growth mature forest and distributed along the forest main footpath margin. After the selection of the 15 sampling points (SPs): five tree-fall gaps, five forest areas, and five edges, we then selected a 50 m2 parcel within each SP. Each parcel was them randomly sampled applying four 50 × 50 cm quadrats in order to collect all the environmental metrics. In these parcels, we measured environmental metrics (microclimate and microhabitat) and we sampled spiders simultaneously as described below.
In order to characterize the tree-fall gaps, forest and edges environmental structure, we measured during the eight survey occasions, the environmental microhabitat and microclimate variables: 1) temperature and relative air moist (range); 2) soil temperature; 3) soil surface temperature; 4) leaf litter layer depth; 5) estimated leaf litter cover; 6) estimated herbaceous vegetation cover; 7) volume of rotten wood (logs and fallen trunks); and 8) light intensity.
1) Temperature (˚C) and relative air moist (%) (range): metrics were taken at the center of the parcel, using a digital thermo hygrometer. The equipment was set on the vegetation, at about 150 cm from the soil surface during all the leaf litter sampling period. We measured the temperature and moist (maximum and minimum), within o ne hour interval and from these measurements we then calculated thermal range; 2) and 3) Soil and soil surface temperature of soil and substrate (˚C): these measurements were taken in 4 locations inside each parcel, at the center of the four quadrats (50 × 50 cm) where we collected the leaf-litter samples. To measure soil temperature we used a digital pen-type thermometer and for soil surface temperature, a digital infrared thermometer. The thermometer was then inserted in the soil; 4) Leaf-litter depth: These measurements were taken in cm, in the same fashion used for metrics two and three. In each quadrant (50 × 50 cm), a plastic ruler was inserted until it reached the soil and the metric sampled; 5) and 6) Leaf-litter and herbaceous vegetation coverage Estimates: Fournier’s adapted technique was applied to measure the percentage index of leaf-litter and vegetation cover. Acategorical quantification method, where values are assigned to categories: 1―(covers 0% to 25%), 2―(26% to 50%), 3―(51% to 75%) and 4―(76% to 100%) [
In order to survey spiders, we sampled leaf-litter and extracted the associated fauna using a mini-Winkler trap. We collected four 50 × 50 cm leaf-litter samples of on each 50 m2 parcels of and placed them in the sieve and strained it. The resultant material remained in the mini-Winkler for 24 h.
At each sampling survey occasion we took 60 leaf-litter samples, 20 in each sampling site (tree-fall gap, forest and edge), totalizing 480 leaf-litter samples over the eight surveys.
An additional night torching survey was applied [
The spiders were identified and deposited in the arachnid collection at the Instituto Butantan, Sao Paulo, Brazil (IBSP, curator: Dr. Irene Knysak). A portion of the biological material was deposited in the UFBA Zoology Museum, Salvador, Bahia, Brazil (MZUFBA, curator: Dr. Adolfo R. Calor).
The following analysis was performed:
1) Spiders species richness was estimated with EstimateS 8.2.0 [
2) We used the matrices to compare species composition among the three vegetation formations (tree-fall gaps, forest and edge). To do so, we have applied a Multiple Response Permutation Procedure (MRPP)-(PC- ORD© 6.0) [
3) A tree-fall gap species composition matrix was created from the main sampling unit’s formation matrix. This matrix was used to compare species composition among the tree fall gaps regeneration. In order to assess whether the spiders assemblage varied significantly over the tree-fall gaps regeneration, we compared four sub phases, between July 2009 and October 2010: Sub phase 1: July to September 2009, Sub phase 2: November 2009 to January 2010, Sub phase 3: March-May 2010 and Sub phase 4: August-October 2010. These sub phases are all included in the gap phase [
We applied the Blocked Multi-Response Permutation Procedures (MRBP)-(PCORD© PC-6.0) [
4) To compare the habitat structure between the three formations (gaps, forest and edge) and along the regeneration of tree fall gaps we built microhabitat and microclimate variables matrices.
To make comparisons between the three formations, we extracted the mean of the data collected over the 16 field surveys and we applied the MRPP. In order to reach that we adopted the same procedures applied in item 3. To compare the four sub phases along their regeneration, we applied the MRBP (Blocked Multi-Response Permutation Procedures = MRPP in blocks). In order to obtain this we adopted the same procedures applied in item 4.
The five selected tree-fall gaps presented areas between 86 and 110 m2 (sd = 11.09). The gaps were originated by uprooting, were recent and adjacent canopy height was estimated between 20 and 30m (sd = 4.18).
The habitat structure was significantly different between the three vegetation types tree-fall gaps, forest and edge (MRPP: p < 0.001; T = −32.642779, A = 0.15145932). When the habitat structure of the formations were pair wise compared, differences between them were also significant. Leaf-litter (depth and coverage) and relative air moist was higher in the forest. The herbaceous vegetation cover, the wood (logs and fallen branches) total volume, temperature (soil and substrate), thermal air and light range were higher in tree-fall gaps (
Habitat Variables | Tree-fall gap | Forest | Edge |
---|---|---|---|
Depth of litter (cm) | 2.7 (±0.58) | 3.2 (±0.70) | 2.4 (±0.71) |
Leaf Litter cover* | 3.5 (±0.64) | 3.9 (±0.35) | 3.4 (±0.67) |
Herbaceous cover* | 3.3 (±0.82) | 2.2 (±0.79) | 3.1 (±0.85) |
Total volume of fallen logs and branches (m3) | 2.05 (±0.04) | 1.40 (±0.03) | 1.71 (±0.04) |
*Measured in the scale of fournier.
Environmental variables | Tree-fall gap | Forest | Edge |
---|---|---|---|
Soil temperature (˚C) | 23.8 (±1.88) | 23.6 (±1.51) | 23.8 (±1.34) |
Substrate temperature (˚C) | 25.9 (±3.73) | 24.3 (±3.20) | 24.7 (±2.21) |
Air temperature range (˚C)* | 3.8 (±1.28) | 3.3 (±1.52) | 3.1 (±1.49) |
Relative air humidity (%) | 73 (±10.78) | 76 (±10.14) | 74 (±10.20) |
Luminosity | 4406 (±11,634) | 412 (±1444) | 2571 (±9181) |
A total of 4732 spiders, including juveniles and adults, divided into 41 families were collected. The most abundant families were Ctenidae (963-20.4%), Araneidae (906-19.15%) and Salticidae (534-11.3%). Among the ad- ult spiders, we recorded a total of 1179 individuals, comprising 126 species, belonging to 36 families. We registered 87 species in tree-fall gaps, 92 in forest and 90 on edges (
Regarding the estimated species richness, the estimated value of the 2nd-order Jackknife (Jack 2) was the highest, indicating a richness of 185 species, whereas the Bootstrap showed the lowest estimates, with 140 species. The remaining estimators Estimates were similar to each other and showed intermediate Jack 1 and Bootstrap values. The estimated species accumulation curve and observed species curves, did not reach an asymptote for any of the three formations (
The first four field surveys (July 2009 to January 2010) data, when tree fall gaps reached eight months, we found significant differences in spiders, species composition, between the three vegetation formations (MRPP, p = 0.00398857, A = 0.01368813, T = −3.0830481). However, when we compared the formations in pairs, no significant difference was found between tree-fall gaps and edges (
We recorded 10 (7.8%) exclusive species in tree-fall gaps, 17 (13.3%) in forests and 14 (11.0%) on edges. However, in partial pair comparisons, these values were higher: tree-fall gaps vs. forest, presented respectively (19 unique species-14.9%; 26% - 20.3%); forest vs edge, respectively (27 unique species-21.0%; 24% - 18.8%) and tree-fall gaps vs. edge, respectively (20 unique species-15.6%; 23% - 18.0%) (
The habitat structure showed significant difference among the four gap sub phases (MRBP, p= 0.0056, T = −3.2479, A = 0.1292). When sub phases were compared pair wise, significant differences were found only between sub phases (1 vs. 3) and (1 vs. 4) (
Trefall gap | Mature forest | Forest edge | Total | |
---|---|---|---|---|
ANYPHAENIDAE | ||||
Hibana sp.1 | 1 | 2 | 0 | 3 |
Isigonia sp.1 | 2 | 2 | 1 | 5 |
ARANEIDAE | ||||
Acacesia sp.1 | 0 | 0 | 1 | 1 |
Alpaidagr. negra | 2 | 0 | 4 | 6 |
Alpaida delicata (Keyserling, 1892) | 1 | 1 | 1 | 3 |
Alpaida sp.1 | 11 | 14 | 14 | 39 |
Alpaida sp.2 | 0 | 0 | 1 | 1 |
Araneus sp.1 | 3 | 2 | 2 | 7 |
Cyclosa fililineata Hingston, 1932 | 2 | 0 | 1 | 3 |
Cyclosa sp.1 | 0 | 3 | 2 | 5 |
Dubiepeira sp.1 | 1 | 0 | 0 | 1 |
Eustala sp.1 | 6 | 2 | 5 | 13 |
Gasteracantha sp.1 | 0 | 0 | 1 | 1 |
Hypognatha sp.1 | 0 | 0 | 3 | 3 |
Kaira sp.1 | 0 | 0 | 1 | 1 |
Mangora sp.1 | 2 | 9 | 1 | 12 |
Melychiopharis sp.1 | 2 | 0 | 0 | 2 |
Metazygia sp.1 | 3 | 3 | 2 | 8 |
Micrathena sp.1 | 19 | 22 | 13 | 54 |
Micrathena sp.2 | 3 | 3 | 3 | 9 |
Micrathena sp.3 | 0 | 0 | 1 | 1 |
Ocrepeira sp.1 | 0 | 1 | 0 | 1 |
Parawixia sp.1 | 6 | 1 | 1 | 8 |
Wagneriana sp.1 | 0 | 2 | 1 | 3 |
CAPONIIDAE | ||||
Nops sp.1 | 1 | 1 | 1 | 3 |
CORINNIDAE | ||||
Castianeira sp.1 | 4 | 1 | 4 | 9 |
Corinna sp.1 | 7 | 10 | 10 | 27 |
Corinnidae sp.1 | 7 | 2 | 4 | 13 |
Ianduba sp.1 | 1 | 0 | 1 | 2 |
Myrmecium sp.1 | 1 | 0 | 0 | 1 |
Orthobula sp.1 | 3 | 5 | 2 | 10 |
Parachemmis sp.1 | 0 | 1 | 0 | 1 |
---|---|---|---|---|
Stethorrhagus sp.1 | 0 | 0 | 2 | 2 |
CTENIDAE | ||||
Ancylometes rufus (Walckenaer, 1837) | 0 | 1 | 0 | 1 |
Celaetycheus sp.1 | 4 | 0 | 10 | 14 |
Ctenidae sp.1 | 1 | 2 | 2 | 5 |
Ctenus ornatus (Keyserling, 1877) | 0 | 4 | 4 | 8 |
Ctenus rectipes F. O. P. Cambridge, 1897 | 14 | 8 | 14 | 36 |
Ctenus sp.1 | 4 | 5 | 6 | 15 |
Enoploctenus cyclothorax (Bertkau, 1880) | 6 | 2 | 4 | 12 |
Enoploctenus maculipes Strand, 1909 | 1 | 0 | 0 | 1 |
Gephyroctenus sp.1 | 0 | 2 | 0 | 2 |
Isoctenus sp.1 | 4 | 10 | 9 | 23 |
Nothroctenus sp.1 | 5 | 3 | 6 | 14 |
Nothroctenus sp.2 | 1 | 0 | 3 | 4 |
CYRTAUCHENIIDAE | ||||
Cyrtaucheniidae sp.1 | 1 | 14 | 4 | 19 |
DEINOPIDAE | ||||
Deinopis sp.1 | 3 | 5 | 0 | 8 |
DIPLURIDAE | ||||
Masteria sp.1 | 5 | 2 | 3 | 10 |
GNAPHOSIDAE | ||||
Gnaphosidae sp.1 | 1 | 1 | 0 | 2 |
HERSILIIDAE | ||||
Ypypuera sp.1 | 4 | 8 | 5 | 17 |
IDIOPIDAE | ||||
Idiops sp.1 | 3 | 1 | 2 | 6 |
LINYPHIIDAE | ||||
Meioneta sp.1 | 5 | 3 | 1 | 9 |
LYCOSIDAE | ||||
Aglaoctenus sp.1 | 0 | 1 | 0 | 1 |
MIMETIDAE | ||||
Ero sp.1 | 0 | 1 | 0 | 1 |
Gelanor sp.1 | 1 | 3 | 6 | 10 |
MITURGIDAE | ||||
Eutichurus sp.1 | 0 | 0 | 1 | 1 |
Miturgidae Gen. Novo | 1 | 3 | 2 | 6 |
---|---|---|---|---|
NEMESIIDAE | ||||
Nemesiidae gen.1 | 1 | 3 | 0 | 4 |
OCHYROCERATIDAE | ||||
Theotima sp.1 | 0 | 1 | 0 | 1 |
OECOBIIDAE | ||||
Oecobius sp.1 | 0 | 1 | 0 | 1 |
OONOPIDAE | ||||
aff. Oonops sp.1 | 1 | 3 | 1 | 5 |
Neoxyphinus sp.1 | 4 | 0 | 0 | 4 |
Oonops sp.1 | 3 | 2 | 0 | 5 |
Gr. Capitato | 3 | 3 | 1 | 7 |
PALPIMANIDAE | ||||
Fernandezina sp.1 | 12 | 21 | 29 | 62 |
Otiothops atlanticus Platnick, Grismado & Ramírez, 1999 | 18 | 12 | 22 | 52 |
PHOLCIDAE | ||||
Carapoia sp.1 | 0 | 1 | 0 | 1 |
Mesabolivar sp.1 | 5 | 6 | 8 | 19 |
PISAURIDAE | ||||
Architis sp.1 | 6 | 6 | 16 | 28 |
Thaumasia sp.1 | 0 | 0 | 1 | 1 |
PRODIDOMIDAE | ||||
Lygromma sp.1 | 4 | 16 | 16 | 36 |
Lygromma sp.2 | 1 | 0 | 1 | 2 |
Lygromma sp.3 | 0 | 1 | 3 | 4 |
SALTICIDAE | ||||
Breda sp.1 | 1 | 0 | 0 | 1 |
Corythalia sp.1 | 0 | 0 | 2 | 2 |
Cotinusasp.1 | 1 | 1 | 0 | 2 |
Lyssomanes sp.1 | 4 | 3 | 0 | 7 |
Noegus sp.1 | 2 | 6 | 0 | 8 |
Salticidae sp.1 | 4 | 7 | 4 | 15 |
Salticidae sp.2 | 2 | 7 | 3 | 12 |
Thiodina sp.1 | 0 | 2 | 0 | 2 |
SCYTODIDAE | ||||
Scytodes sp.1 | 2 | 2 | 0 | 4 |
SENOCULIDAE | ||||
---|---|---|---|---|
Senoculus sp.1 | 1 | 1 | 2 | 4 |
SPARASSIDAE | ||||
Olios sp.1 | 16 | 19 | 8 | 43 |
Sparianthinae sp.1 | 4 | 7 | 0 | 11 |
Thomasettia sp.1 | 3 | 3 | 3 | 9 |
SYNOTAXIDAE | ||||
Synotaxus sp.1 | 0 | 2 | 1 | 3 |
TETRAGNATHIDAE | ||||
Aziliahistrio Simon, 1895 | 13 | 7 | 11 | 31 |
Chrysometa sp.1 | 0 | 1 | 0 | 1 |
Cyrtognatha sp.1 | 1 | 1 | 6 | 8 |
Leucauge sp.1 | 2 | 3 | 6 | 11 |
THERAPHOSIDAE | ||||
Ischnocolinae sp.1 | 1 | 1 | 0 | 2 |
Magulla sp.1 | 0 | 3 | 0 | 3 |
Plesiopelma sp.1 | 0 | 0 | 4 | 4 |
Theraphosidae sp.1 | 1 | 4 | 2 | 7 |
THERIDIIDAE | ||||
Achaearanea sp.1 | 1 | 0 | 0 | 1 |
Argyrodes elevatus Taczanowski, 1873 | 0 | 1 | 0 | 1 |
Argyrodes sp.1 | 0 | 1 | 1 | 2 |
Chrosiothes sp.1 | 0 | 0 | 1 | 1 |
Chrysso sp.1 | 7 | 4 | 3 | 14 |
Dipoena sp.1 | 3 | 11 | 5 | 19 |
Dipoena sp.2 | 1 | 0 | 1 | 2 |
Dipoena sp.3 | 0 | 1 | 2 | 3 |
Dipoena sp.4 | 3 | 0 | 3 | 6 |
Episinus gr. cognatus | 10 | 10 | 13 | 33 |
Episinus sp.1 | 1 | 9 | 10 | 20 |
Episinus sp.2 | 0 | 0 | 2 | 2 |
Episinus sp.3 | 1 | 1 | 2 | 4 |
Euryopis sp.1 | 0 | 0 | 1 | 1 |
Nesticodes rufipes (Lucas, 1846) | 10 | 1 | 0 | 11 |
Spintharus sp.1 | 0 | 6 | 3 | 9 |
Theridiidae sp.1 | 4 | 2 | 1 | 7 |
Theridion sp.1 | 4 | 0 | 2 | 6 |
THERIDIOSOMATIDAE | ||||
---|---|---|---|---|
Chthonos sp.1 | 0 | 2 | 0 | 2 |
Naatlo sp.1 | 1 | 6 | 2 | 9 |
Plato sp.1 | 3 | 4 | 0 | 7 |
Theridiosomatidae Gen. Novo | 2 | 0 | 2 | 4 |
THOMISIDAE | ||||
aff. Tmarus sp.1 | 0 | 0 | 1 | 1 |
Aphantochilusrogersi O. P.-Cambridge, 1870 | 0 | 0 | 1 | 1 |
Tmarus sp.1 | 2 | 5 | 15 | 22 |
Tmarus sp.2 | 0 | 1 | 1 | 2 |
TRECHALEIDAE | ||||
Trechalea sp.1 | 4 | 2 | 2 | 8 |
ULOBORIDAE | ||||
Uloborus sp.1 | 0 | 0 | 4 | 4 |
Miagrammopes sp.1 | 3 | 11 | 3 | 17 |
Zosis sp.1 | 7 | 1 | 3 | 11 |
ZODARIIDAE | ||||
Tenedos sp.1 | 3 | 38 | 3 | 44 |
Species richness | 87 | 92 | 90 | 126 |
T | A | p | US | |
---|---|---|---|---|
Tree-fall gap vs. Edge | −1.671 | 0.0079 | 0.0608 | 20 and 23 |
Tree-fall gap vs. Forest | −1.830 | 0.0827 | 0.0470 | 19 and 26 |
Edge vs. Forest | −3.053 | 0.0152 | 0.0059 | 24 and 27 |
Sub phases | Estimated age (in months)* | T | A | p |
---|---|---|---|---|
1 vs. 2 | 4 vs. 8 | −1.247 | 0.0692 | 0.1107 |
1 vs. 3 | 4 vs. 12 | −1.986 | 0.1167 | 0.0477 |
1 vs. 4 | 4 vs. 16 | −2.313 | 0.1732 | 0.0339 |
2 vs. 3 | 8 vs. 12 | −0.249 | 0.0064 | 0.3910 |
2 vs. 4 | 8 vs. 16 | −0.989 | 0.0630 | 0.1420 |
3 vs. 4 | 12 vs. 16 | −1.358 | 0.1280 | 0.0973 |
*Maximum estimated age.
The spider species’ composition differ significantly among the four sub phases (MRBP, p = 0.0047, T = −3.007, A = 0.2994). When we compared the sub phases pair wise, we found significant differences only between the sub phase four and the other sub phases (
The tree-fall gaps formations in fact promoted significant changes in environmental structure in relation to the adjacent forest, specifically in relation to microclimatic and microhabitat variables. Such differences have been reported in several studies in tropical forests [
The tree-fall gaps formation triggered significant changes in the spiders’ assemblage in relation to the adjacent forest. This differentiation was observed in habitat structure and thus corroborated the association of spider assemblage’s with microclimate and microhabitat variables, as reported by other studies. The habitat structure influence the spider’s species’ assemblages’ composition and/or richness [
Sub-phases | Estimated age (in months)* | T | A | p |
---|---|---|---|---|
1 vs. 2 | 4 vs. 8 | −0.9087 | 0.0088 | 0.1765 |
1 vs. 3 | 4 vs. 12 | 0.0363 | −0.0004 | 0.5229 |
1 vs. 4 | 4 vs. 16 | −2.4134 | 0.0454 | 0.0200 |
2 vs. 3 | 8 vs. 12 | −0.0153 | 0.0001 | 0.4832 |
2 vs. 4 | 8 vs. 16 | −1.9200 | 0.0199 | 0.0357 |
3 vs. 4 | 12 vs. 16 | −2.7010 | 0.05411 | 0.0157 |
*Maximum estimated age.
Higher habitat heterogeneity allows orb-weaver spiders’ occurrence, since this habitat quality increases the shelter offer for species settlement [
Certainly, light in tree-fall gaps is the main variable that controls microclimate and other variables that make tree-fall gaps different from adjacent forest [
The leaf-litter complexity affects the spider assemblages [
In contrast, higher luminosity in tree-fall gaps and edges promotes greater herbaceous vegetation cover, also contributing to increase of herbivores [
In conclusion, tree-fall gaps, even the small ones, have a crucial role in the dynamics of spider’s assemblages in the Atlantic forest. The spatial effect is pronounced but the temporal effect, although detected by in the spiders’ assembly, should be evaluated in the long-term (>4 years).
The authors are grateful to the Ecological Reserve Michelin for their excellent support, by providing us with necessary infrastructure and logistics during field campaigns. To Lacerta Ambiental by lending field equipment. M. C. L. P. is supported by Programa de Regime de Tempo Contínuo (RTC) of Universidade Católica do Salvador. J.H.C.D. is a CNPq fellow.