An examination of scale of assessment,logging and ENSO-induced fires on butterfly diversity in Borneo

The impact of disturbance on species diversity may be related to the spatial scales over which it occurs. Here I assess the impact of logging and ENSO (El Niño Southern Oscillation) -induced burning and forest isolation on the species richness (477 species out of more than 28,000 individuals) and community composition of butterflies and butterfly guilds using small (0.9 ha) plots nested within large (450 ha) landscapes. The landscapes were located in three habitat classes: (1) continuous, unburned forest; (2) unburned isolates surrounded by burned forest; and (3) burned forest. Plots with different logging histories were sampled within the two unburned habitat classes, allowing for independent assessment of the two disturbance factors (logging and burning). Disturbance within habitat classes (logging) had a very different impact on butterfly diversity than disturbance among habitat classes (due to ENSO-induced burning and isolation). Logging increased species richness, increased evenness, and lowered dominance. Among guilds based on larval food plants, the species richness of tree and herb specialists was higher in logged areas but their abundance was lower. Both generalist species richness and abundance was higher in logged areas. Among habitat classes, species richness was lower in burned forest and isolates than continuous forest but there was no overall difference in evenness or dominance. Among guilds, generalist species richness was significantly lower in burned forest and isolates than continuous forest. Generalist abundance was also very low in the isolates. There was no difference among disturbance classes in herb specialist species richness but abundance was significantly higher in the isolates and burned forest than in continuous forest. Tree specialist species richness was lower in burned forest than continuous forest but did not differ between continuous forest and isolates.The scale of assessment proved important in estimating the impact of disturbance on species richness. Within disturbance classes, the difference in species richness between primary and logged forest was more pronounced at the smaller spatial scale. Among disturbance classes, the difference in species richness between continuous forest and isolates or burned forest was more pronounced at the larger spatial scale. The lower levels of species richness in ENSO-affected areas and at the larger (landscape) spatial scale indicate that future severe ENSO events may prove one of the most serious threats to extant biodiversity.     

Diversity Patterns of Bornean Butterfly Assemblages

Borneo contains a diverse rainforest butterfly community, but its forests are under threat from logging and ENSO- (El Niño Southern Oscillation) induced fires. Contrasts in butterfly assemblage structure were examined in nine 450 ha landscapes in logged forest, primary unburned continuous and isolated forest, and forest affected by surface fires during the 1997/98 ENSO event. Temporally the effect of the 1997/98 ENSO event was followed in a single burned landscape from 1997 to 2004. In total, 517 species were present in 190 sampling sites. There was a five-fold difference in species richness among landscapes, with highest richness in continuous landscapes and lowest richness in burned landscapes. Richness was also higher in logged forest than proximate unlogged forest. Temporally, species richness dropped dramatically from 1997 to 1998, but afterwards increased remaining, however, substantially lower than pre-ENSO (1997) sampling. Sites in burned landscapes were distinct from other sites in terms of vegetation structure with the slash-and-burn area the most dissimilar to other landscapes. There was much less structure among unburned landscapes. The pattern of butterfly community composition was similar to that of vegetation structure with the community from the slash-and-burn area the most distinct. However, there was much less overlap among sites from different landscapes. Temporally, 1998 possessed the most distinct assemblage when compared to assemblages from other years. The community composition was, however, slowly returning to a pre-disturbance composition. Variance in community composition explained by environmental and spatial factors differed substantially among landscapes. The spatial fraction was the only explanatory component in recently burned landscapes and a proximate small unburned isolate, but explained no variation in logged landscapes. The environmental fraction explained substantial amounts of variation in logged landscapes and the slash-and-burn area. When all landscapes were pooled high proportions of variation in butterfly community composition were explained by both geographic distance between sites and environmental variables. In contrast when only unburned landscapes were considered, most variation was explained by the geographic distance among them. Despite differences among landscapes there was a general pattern of relatively sharp decline in similarity at short distances that levels out over greater distances, a result that agrees with previous studies on other tropical species assemblages.     

Diversity and community composition of butterflies and odonates in an ENSO-induced fire affected habitat mosaic: a case study from East Kalimantan, Indonesia

Little is known about the diversity of tropical animal communities in recently fire‐affected environments. Here we assessed species richness, evenness, and community similarity of butterflies and odonates in landscapes located in unburned isolates and burned areas in a habitat mosaic that was severely affected by the 1997/98 ENSO (El Niño Southern Oscillation) event in east Kalimantan, Indonesian Borneo. In addition related community similarity to variation in geographic distance between sampling sites and the habitat/vegetation structure Species richness and evenness differed significantly among landscapes but there was no congruence between both taxa. The species richness of butterflies was, for example, highest in sites located in a very large unburned isolate whereas odonate species richness was highest in sites located in a small unburned isolate and once‐burned forest. We also found substantial variation in the habitat/vegetation structure among landscapes but this was mainly due to variation between unburned and burned landscapes and variation among burned landscapes. Both distance and environment (habitat/vegetation) contributed substantially to explaining variation in the community similarity (beta diversity) of both taxa. The contribution of the environment was, however, mainly due to variation between unburned and burned landscapes, which contained very different assemblages of both taxa. Sites located in the burned forest contained assemblages that were intermediate between assemblages from sites in unburned forest and sites from a highly degraded slash‐and‐burn area indicating that the burned forest was probably recolonised by species from these disparate environments. We, furthermore, note that in contrast to species richness (alpha diversity) the patterns of community similarity (beta diversity) were highly congruent between both taxa. These results indicate that community‐wide multivariate measures of beta diversity are more consistent among taxa and more reliable indicators of disturbance, such as ENSO‐induced burning, than univariate measures.     

Impacts of Intensive Logging on the Trophic Organisation of Ant Communities in a Biodiversity Hotspot

Trophic organisation defines the flow of energy through ecosystems and is a key component of community structure. Widespread and intensifying anthropogenic disturbance threatens to disrupt trophic organisation by altering species composition and relative abundances and by driving shifts in the trophic ecology of species that persist in disturbed ecosystems. We examined how intensive disturbance caused by selective logging affects trophic organisation in the biodiversity hotspot of Sabah, Borneo. Using stable nitrogen isotopes, we quantified the positions in the food web of 159 leaf-litter ant species in unlogged and logged rainforest and tested four predictions: (i) there is a negative relationship between the trophic position of a species in unlogged forest and its change in abundance following logging, (ii) the trophic positions of species are altered by logging, (iii) disturbance alters the frequency distribution of trophic positions within the ant assemblage, and (iv) disturbance reduces food chain length. We found that ant abundance was 30% lower in logged forest than in unlogged forest but changes in abundance of individual species were not related to trophic position, providing no support for prediction (i). However, trophic positions of individual species were significantly higher in logged forest, supporting prediction (ii). Consequently, the frequency distribution of trophic positions differed significantly between unlogged and logged forest, supporting prediction (iii), and food chains were 0.2 trophic levels longer in logged forest, the opposite of prediction (iv). Our results demonstrate that disturbance can alter trophic organisation even without trophically-biased changes in community composition. Nonetheless, the absence of any reduction in food chain length in logged forest suggests that species-rich arthropod food webs do not experience trophic downgrading or a related collapse in trophic organisation despite the disturbance caused by logging. These food webs appear able to bend without breaking in the face of some forms of anthropogenic disturbance.     

Effects of rain forest logging on species richness and assemblage composition of small mammals in Southeast Asia

Aim The effects of logging and habitat degradation on the richness and abundance of small mammals in Asian rain forests are largely unknown. This work compares the species richness, dominance and evenness of small non‐volant mammals between logged and unlogged forests, and assesses whether assemblage variability (β‐diversity) is similar between forest types. Location Southeast Asia, northern Borneo (Sabah, Malaysia), Sunda‐shelf. Methods We surveyed species‐rich assemblages of small non‐volant mammals in three unlogged and three logged forests for 2 years. At each forest site, we sampled a permanently marked transect and two additional sites in three trapping sessions. All analyses were performed at both levels to include the effects of local abundances and point estimates, separately from the relative abundances of species on a more regional scale. Results We trapped a total of 1218 individuals of 28 species. Eleven common species accounted for 95% of all captures. Species richness and diversity were significantly higher in unlogged forest (27 species) than in logged forest (17 species). This was mainly attributable to the smaller number of rarely recorded species in logged forest (five compared with 16 in unlogged forest, with a total of fewer than 10 captures). However, all common species were present in both logged and unlogged forests, and our analyses revealed similar patterns of dominance, evenness and fluctuations in abundance. Hence overall assemblage composition in multivariate space did not differ greatly between forest types. Assemblages of Muridae and Tupaiidae showed similar population fluctuations in space and time, indicating that the ecology of these taxa may be partially driven by the same environmental factors. Main conclusions Although species were distributed patchily within sites, analyses at local and regional scales revealed similar patterns in diversity and assemblage variability, suggesting that effects of forest modification did not differ extensively locally and regionally, but had a profound effect on rare species. Our results emphasize the importance and conservation value of logged forest stands that are able to hold a large proportion of the small mammals also found in unlogged forests. Rare and more specialized species are more vulnerable to forest degradation than commonly caught species, resulting in the complete loss, or a decrease in numbers, of certain groups, such as arboreal small mammals and Viverridae.     

Vegetation responses to burning in a rain forest in Borneo

During the 1997/98 ENSO (El Niño Southern Oscillation) event more than 5 million ha of East Kalimantan, Indonesia burned. Here we quantify the initial stages of regeneration (19982001), both in forest that burned and in unburned controls. Sapling and seedling density and species richness remained significantly lower in burned than in unburned forest and community composition remained substantially different between both forest types throughout the sampling period. The only pronounced edge effect was a significantly higher density of seedlings in the interior of unburned forest. Sapling density increased and seedling density declined in both unburned and burned forest during the four-year study period. In the unburned forest, sapling and seedling species richness remained stable, but sapling species richness declined significantly with time in the burned forest. The pioneer community in the burned forest was, furthermore, characterised by higher growth and recruitment than in the unburned forest but mortality did not differ between both forest types. Differences in environment (burned versus unburned: 2965% of variation explained) and the distance between sample sites (1323% of variation explained) explained substantial amounts of variation in sapling and seedling community similarity. Similarity was, however, only marginally (< 1% explained) related to the edge position and temporal variation (difference among sample events). Our results, four years after the initial burn, indicate that burned forest still differed greatly from unburned forest in terms of density, species richness and community composition. There was also no clear trend of a return to pre-disturbance conditions, which indicates that the burned forest may remain in a severely degraded state for a prolonged period of time.     

Long‐term Changes in Bird Communities after Wildfires in the Central Brazilian Amazon

We examined long‐term responses of an Amazonian bird assemblage to wildfire disturbance, investigating how understory birds reacted to forest regeneration 1, 3, and 10 years after a widespread fire event. The bird community was sampled along the Arapiuns and Maró river catchments in central Brazilian Amazonia. Sampling took place in 1998, 2000, and 2008 using mist‐nets in eight plots (four burned, four unburned sites). Species richness did not change significantly in unburned sites. In burned sites, however, we found significantly lower richness in 1998, higher richness in 2000, and similar richness in 2008. Multi‐dimensional scaling ordination showed consistent differences in bird communities both within burned sites sampled in different sampling years, and between burned and unburned sites in all years. Of the 30 most abundant species, 12 had not recovered 10 years after the fires, including habitat specialists such as mixed flocks specialists and ant‐followers. Fire‐disturbance favored three species (two hummingbirds and a manakin) in the short term only. All other species were either favored throughout the study (seven species of omnivores and small insectivores) or did not show a clear response (eight species). In burned sites, we also found significantly lower abundance of species sensitive to disturbances and habitat specialists over the entire study period. Although the bird community seems to be recovering in terms of richness, the overall community composition and abundance of some species in post‐burned and unburned sites remain very different, and have not recovered after 10 years of forest regeneration.     

Does selective logging change ground‐dwelling beetle assemblages in a subtropical broad‐leafed forest of China?

Selective logging with natural regeneration is advocated as a near‐to‐nature strategy and has been implemented in many forested systems during the last decades. However, the efficiency of such practices for the maintenance of forest species are poorly understood. We compared the species richness, abundance and composition of ground‐dwelling beetles between selectively logged and unlogged forests to evaluate the possible effects of selective logging in a subtropical broad‐leafed forest in southeastern China. Using pitfall traps, beetles were sampled in two naturally regenerating stands after clearcuts (ca. 50 years old, stem‐exclusion stage: selectively logged 20 years ago) and two mature stands (> 80 years old, understory re‐initiation stage: selectively logged 50 years ago) during 2009 and 2010. Overall, selective logging had no significant effects on total beetle richness and abundance, but saproxylic species group and some abundant forest species significantly decreased in abundance in selectively logged plots compared with unlogged plots in mature stands. Beetle assemblages showed significant differences between selectively logged and unlogged plots in mature stands. Some environmental characteristics associated with selective logging (e.g., logging strategy, stand age, and cover of shrub and moss layers) were the most important variables explaining beetle assemblage structure. Our results conclude that selective logging has no significant impacts on overall richness and abundance of ground‐dwelling beetles. However, the negative effects of selective logging on saproxylic species group and some unlogged forest specialists highlight the need for large intact forested areas for sustaining the existence of forest specialist beetles.     

Effects of Selection Logging on Birds in Northern Belize1

We compared bird diversity and frequency in selection logged and unlogged forest to determine the effects of recent selection logging on avian biodiversity in a subtropical, moist evergreen forest. We used a combination of mist netting and fixed-radius point counts to assess bird communities in February and March 1993 in northwestern Belize. Vegetation structure and composition was similar in logged and unlogged forest. The 66 most common species occurred with statistically similar frequency in logged and unlogged forest although 13 species were two times more frequent in intact forest. Numbers of total bird species were similar between logging gaps and the logged forest matrix, and between the logged forest matrix and unlogged forests. A comparison of numbers of species in 26 guilds based on migration strategy, diet, foraging substrate, and height strata also showed them to be similar regardless of logging history. Our results differed from previous studies that reported lower bird species richness and abundance of individual species in logged tropical forests than in unlogged forest. The differences might be explained by the lower logging intensity and/or greater levels of natural disturbance in our study area compared to previous studies.     

The impact of logging on the abundance, species richness and community composition of butterfly guilds in Borneo

Abstract:  The impact of logging on the relative abundance, species richness and community composition of four butterfly guilds (generalists, herb specialists, liana specialists and tree specialists) was assessed in differentially disturbed logging treatments located within the province of Central Kalimantan, Indonesian Borneo. Logging affected the overall butterfly composition by increasing the dominance of liana specialists at the expense of tree specialists and increasing the species richness of herb specialists and, to a lesser extent, generalists. There was no significant difference, however, in the species richness of liana specialists or tree specialists across logging treatments. The species composition of all guilds differed significantly among logging treatments with the greatest difference between unlogged forest and road sites with older and recently logged forest intermediate between these extremes. Our results indicate that logging has a disparate effect on abundance and species richness within each butterfly guild. We suggest that shifts in the dominance of butterfly guilds are due to large-scale logging-induced changes in vegetation, particularly in relation to liana abundance. The higher butterfly species richness in logged areas on the other hand is probably because of butterfly species associated with open areas entering the logged forest from roads or other large open areas.     

Changes in avian communities of Budongo Forest Reserve after 70 years of selective logging

Owiunji, I. 2000. Changes in avian communities of Budongo Forest Reserve after 70 years of selective logging. Ostrich 71 (1 & 2): 216–219.

Budongo Forest Reserve, located in the west of Uganda, has been selectively logged for timber for over 70 years, and has a well documented management history. Changes in the avian community, species diversity and relative densities were assessed in two unlogged and three logged and arboricidally treated compartments. Tree-species diversity was highest in the disturbed forest. Over 100 forest bird species were recorded (including a new record for East Africa, Puvel's Illadopsis Illadopsis puveli. Both point counts and mist-netting showed that bird species diversity was higher in the logged and treated than in the unlogged forest. Five species had significantly higher densities in logged forest, three species had significantly higher densities in unlogged forest and 14 species showed no significant change in densities. The response of Budongo Forest birds to disturbance was species-specific.     

Effects of Historical Selective Logging on Anuran Communities in a Wet Evergreen Forest,South India

Vast areas of tropical evergreen forests have been selectively logged in the past, and many areas continue to be logged. The impacts of such logging on amphibians are poorly understood. I examined the response of anuran communities to historical selective logging in a wet evergreen forest in south India. Anuran assemblages in unlogged forest were compared with assemblages in selectively logged forest. Forty 10 m × 10 m quadrats in forest, riparian zones, and streams of unlogged and selectively logged forests were searched at night for anurans. Species richness did not appear to be affected by logging. However, anuran density varied significantly and was 42 percent lower in selectively logged forests compared to unlogged forests. Anuran densities also varied significantly across microhabitats, with highest densities in streams of both selectively logged and unlogged forests. Patterns of niche overlap varied with selective logging as niche breadth either expanded, contracted, or remained neutral for different species. Ordination analysis explained 95 percent of the variation in species assemblage across selectively logged and unlogged forests. The assemblage in selectively logged forest was nested within unlogged forest. Among the habitat characteristics, litter thickness and water depth had the highest influence on the assemblage. This was followed by litter/water temperature, air temperature, and lastly relative humidity. It appears that species richness and composition of anurans in selectively logged forests is converging with unlogged forests, but the effects of historical logging seem to persist on anuran densities and their niche characteristics even ca 40 yr since logging ceased.     

Effects of Postfire Logging on Soil and Vegetation Recovery in a Pinus halepensis Mill. Forest of Greece

After a wildfire in a Pinus halepensis Mill. forest, in northern Greece, the burned trees were logged and the logs were removed either by mechanical or animal traction. The effects of logging and log removal methods on soil and vegetation recovery were evaluated comparing the logged sites with a burned but unlogged site and the unburned forest. Fire and logging did not affect the soil pH and caused only a short-term reduction in organic matter content. Two years after the fire, the highest rates of soil loss were observed in the logged area where mules were used for log removal. Soil moisture showed some differences between treatments during the first year after fire but then values were similar. Logging and particularly the use of skidders for log removal caused an initial increase in the amount of exposed bare ground but later when vegetation cover increased differences were minimized. The main woody species showed a species specific response to the treatments and while seeder species were favoured in the unlogged sites the same was not true for the respouters. In general, the growth and survival of pine seedlings was not affected by treatments.     

Patterns of Richness and Abundance in a Tropical African Leaf‐litter Herpetofauna1

I compared species richness and habitat correlates of leaf‐litter herpetofaunal abundance in undisturbed and selectively logged forests, and an abandoned pine plantation in Kibale National Park, Uganda. I sampled 50 randomly located 25 m² litter plots in each area during the wet and dry seasons in 1997. Ten anuran, five lizard, and three snake species were captured in plots over the study. Assemblage composition was most similar at logged and unlogged sites. The logged forest herpetofauna had higher species richness and abundance than the unlogged forest, but diversity was greater in the unlogged forest due to greater evenness. In contrast, the pine plantation site had the highest richness, abundance, and evenness of the three study sites, but species composition was distinct from the other areas. Herpetofaunal densities were significantly lower in all three areas during the dry season than in the wet season. During the dry season, soil moisture, litter mass, topography, shrub cover, and number of fallen logs were significant positive predictors of herpetofaunal presence in litter plots, but only soil moisture was significant in the wet season. The interaction of moisture and topography appears to be important in determining seasonal patterns of litter herpetofaunal distribution. Comparison of litter herpetofaunal studies across the tropics have shown that mid‐elevation faunas generally support fewer species than lowland faunas. Compared with other tropical mid‐elevation litter faunas, Kibale supports an intermediate number of species, but at lower densities than observed at any other mid‐elevation site reported in the literature.     

Impact of deforestation on the abundance,diversity, and richness of Culex mosquitoes in a southwest Cameroon tropical rainforest

Deforestation is a major threat to biodiversity but little data exist on how deforestation in real‐time affects the overall mosquito species community despite its known role in the transmission of diseases. We compared the abundance and diversity of Culex mosquitoes before and after deforestation along a gradient of three different anthropogenic disturbance levels in a tropical rainforest in southwestern Cameroon. The collections were conducted in unlogged forest (January, 2016), selectively logged forest (January, 2017), and within a young palm plantation (October, 2017) using net traps, sweep nets, resting traps, and dipping for immature stages in water bodies. Mosquitoes were morphologically identified to subspecies, groups, and species. A total of 2,556 mosquitoes was collected of which 1,663 (65.06%) belong to the genus Culex, (n=427 (25.68%) in the unlogged forest; n=900 (54.12%) in the selectively logged forest; and n=336 (20.2%) in the young palm plantation) with a significant difference among the habitats. Diversity and richness of mosquitoes varied significantly among habitats with the highest values found in the selectively logged forest (H=2.4; DS=0.87; S=33) and the lowest value in the unlogged forest (H=1.37; DS=0.68; S=13). The results of this study showed that deforestation affects the abundance and diversity of Culex mosquitoes and favors the invasion of anthropophilic mosquitoes. Higher mosquito abundance and diversity in the selectively logged forest than in the pristine forest is notable and some explanations for these differences are discussed.     

Forest Regeneration in Logged and Unlogged Forests of Kibale National Park, Uganda

Processes of forest regeneration in two unlogged areas and in three areas that were logged nearly 25 years ago were quantified in Kibale National Park, Uganda. For forests to recover from logging, one would predict recruitment and growth processes to be accelerated in logged areas relative to unlogged areas, facilitating increased recruitment of trees into the adult size classes. We examined this prediction first by determining the growth of 4733 trees over a 51 to 56 month period and found that growth rates in the most heavily logged area were consistently slower than in the two unlogged areas. In contrast, the lightly logged forest had similar growth rates to unlogged areas in the small size classes, but trees in the 30 to 50 cm DBH size cohort exhibited elevated growth rates relative to the unlogged areas. Mortality was highest in the heavily logged areas, with many deaths occurring when healthy trees were knocked over by neighboring treefalls. We found no difference in the density or species richness of seedlings in the logged and unlogged forests. The number of seedlings that emerged from the disturbed soil (seed bank+seed rain) and initially seed-free soil (seed rain) was greater in the logged forest than in the unlogged forest. However, sapling density was lower in the heavily logged areas, suggesting that there is a high level of seedling mortality in logged areas. We suggest that the level of canopy opening created during logging, the lack of aggressive colonizing tree species, elephant activity that is concentrated in logged areas, and an aggressive herb community, all combine to delay vegetation recovery in Kibale Forest.     

The conservation value of unlogged and logged forests for native mammals on the East Coast of Peninsular Malaysia

Tropical forests across the world provide important habitats for a diverse number of conservation priority species, yet are under threat from a range of anthropogenic impacts including logging. This study aims to quantify mammalian biodiversity in unlogged and logged forests in the adjoining Tembat and Petuang Forest Reserves, Terengganu, on the East Coast of Peninsular Malaysia. Data was collected over a series of surveys using direct and indirect observation methods from 2008 to 2014. A total of 30 medium and large sized mammals species were identified, with 27 of those species found in unlogged forests and 22 species in logged forests. Carnivores encompassed 11 species from 67 observations representing 15% of the total number of observations. The family Felidae had the highest number of species (six species), followed by Hylobatidae, Cercopithecidae and Suidae with three species each. A total of 17 species contributed to more than 90% of the mammal community in the unlogged and logged forests, while six species were uncommon and only observed once during the entire survey. Species abundance in the unlogged forest was significantly greater than the logged forests, but the difference was not significant for species richness. This study provides critical baseline information on the impact of unlogged and logged forests and the identification of threatened species warrant the establishment of conservation measures such as anti-poaching patrol and ranger stations in the study area.     

Feeding ecology and dietary differences between blue monkey (Cercopithecus mitis stuhlmanni Matschie) groups in logged and unlogged forest, Budongo Forest Reserve, Uganda

Several studies have investigated the effects of logging on primate population density, and attempted to relate density differences to changes in vegetation composition. As population density in some forest primates may be considerably influenced by dietary quality, it is important to understand how the effects of vegetation changes commonly associated with logging influence primate feeding ecology. Results are presented from a study carried out in the Budongo Forest Reserve in Uganda to investigate differences in blue monkey (Cercopithecus mitis stuhlmanni) feeding ecology in forest blocks with different logging history. Dietary composition differed between logged and unlogged forest, with a higher proportion of unripe fruit consumed in logged forest. By contrast, the proportion of young leaves, invertebrates and seeds in the diet was higher in unlogged forest. Variations in the intake of fruit was also higher in unlogged forest, but feeding patterns on other dietary items were more selective. These differences in diet reflect differences in availability of different categories of food items, as determined by tree species composition, abundance and plant phenological patterns. The observed differences between feeding ecology in logged and unlogged forest are discussed in relation to primate feeding ecology and habitat composition in Budongo.     

Leaf litter decomposition rates in degraded and fragmented tropical rain forests of Borneo

Previously extensive tracts of primary rain forest have been degraded by human activities, and we examined how the effects of forest disturbance arising from habitat fragmentation and commercial selective logging affected ecosystem functioning in these habitats by studying leaf litter decomposition rates in litter bags placed on the forest floor. The rain forests of Borneo are dominated by trees from the family Dipterocarpaceae, and we compared leaf litter decomposition rates of three dipterocarp species at eight forest fragment sites (area 3–3529 ha) that had different histories of disturbance pre‐fragmentation: four fragments had been selectively logged prior to fragmentation and four had been formed from previously undisturbed forest. We compared these logged and unlogged forest fragments with sites in continuous forest that had been selectively logged (two sites) and fully protected and undisturbed (two sites). After 120 d, undisturbed continuous forest sites had the fastest rates of decomposition (52% mass loss). Forest fragments formed from unlogged forest (32% mass loss) had faster decomposition rates than logged forest fragments (28% mass loss), but slower rates than continuous logged forest (39% mass loss). Leaves of a light‐demanding species (Parashorea malaanonan) decomposed faster than those of a shade‐tolerant species (Hopea nervosa), but decomposition of all three dipterocarp species that we studied responded similarly to logging and fragmentation effects. Reduced decomposition rates in logged and fragmented forest sites may affect nutrient cycling and thus have detrimental consequences for forest regeneration. Conservation management to improve forest quality should be a priority, particularly in logged forest fragments.     

Butterfly,seedling, sapling and tree diversity and composition in a fire‐affected Bornean rainforest

Abstract: Fire‐affected forests are becoming an increasingly important component of tropical landscapes. The impact of wildfires on rainforest communities is, however, poorly understood. In this study the density, species richness and community composition of seedlings, saplings, trees and butterflies were assessed in unburned and burned forest following the 1997/98 El Niño Southern Oscillation burn event in East Kalimantan, Indonesia. More than half a year after the fires, sapling and tree densities in the burned forest were only 2.5% and 38.8%, respectively, of those in adjacent unburned forest. Rarefied species richness and Shannon's H’ were higher in unburned forest than burned forest for all groups but only significantly so for seedlings. There were no significant differences in evenness between unburned and burned forest. Matrix regression and Akaike's information criterion (AIC) revealed that the best explanatory models of similarity included both burning and the distance between sample plots indicating that both deterministic processes (related to burning) and dispersal driven stochastic processes structure post‐disturbance rainforest assemblages. Burning though explained substantially more variation in seedling assemblage structure whereas distance was a more important explanatory variable for trees and butterflies. The results indicate that butterfly assemblages in burned forest were primarily derived from adjacent unburned rainforest, exceptions being species of grass‐feeders such as Orsotriaena medus that are normally found in open, disturbed areas, whereas burned forest seedling assemblages were dominated by typical pioneer genera, such as various Macaranga species that were absent or rare in unburned forest. Tree assemblages in the burned forest were represented by a subset of fire‐resistant species, such as Eusideroxylon zwageri and remnant dominant species from the unburned forest.