Species composition and diversity of small Afromontane forest fragments in northern Ethiopia

In the highlands of northern Ethiopia, remnants of the original Afromontane forest vegetation are largely restricted to church yards and other sacred groves in a matrix of cropland and semiarid degraded savanna. To assess the potential for natural forest regeneration, species composition and diversity of all forest fragments (10) in a study area of 13,000 ha were analyzed in relation to environmental and soil variables. Using a random design and a density of approximately one plot per 2 ha in all fragments, 31 20×20 m plots were sampled. Indicator species analysis and MRPP tests yielded five communities representing two forest types and one degraded savanna habitat. The forest fragments had a species-poor tree and shrub community in which plots were rather homogeneous and most species abundant. NMDS and analysis of variance indicated that a topographical gradient correlated to soil phosphorus, soil depth, stoniness and the proximity to the river system explained the major differences in species composition and separated moist and dry Afromontane forest communities. The grazing intensity further partitioned the habitats. Present communities and their environmental correlates indicate that the secondary climax forest in the area probably consisted of dry Afromontane forest interlaced by broad strips of moist Afromontane forest along rivers and streams and not a continuous, mono-dominant Juniperus forest as is often presumed. Negative effects of the degraded matrix on forest fragments increased with decreasing patch area and increasing shape irregularity. Nevertheless, all remaining fragments are important for their role in the landscape ecology of the region as refuges and species pools and should be protected and managed accordingly. If seed dispersal from forest fragments into exclosures and subsequent tree recruitment are both successful, the vegetation type most likely to establish is Afromontane savanna woodland, and if managed properly, eventually dry Afromontane forest may arise. Increasing the size of small patches and placing forest plantations and exclosures in the vicinity of small forest fragments is expected to yield the most immediate results. This approach may increase the likelihood of patch colonisation by frugivorous forest birds and thus foster the regeneration of native woody species.     

Comparing bird assemblages in large and small fragments of the Atlantic Forest hotspots

The Atlantic Forest (AF) is one of the five most threatened and megadiverse world hotspots. It is arguably the most devastated and highly threatened ecosystem on the planet. The vast scope of habitat loss and extreme fragmentation in the AF hotspots has left intact very few extensive and continuous forested fragments. We compared bird assemblages between small (<100 ha) and large (>6,000 ha) forest remnants, in one of the largest AF remnants in Argentina. We performed 84 point-counts of birds in four large fragments (LF) and 67 points in 25 small fragments (SF). We recorded 4,527 bird individuals belonging to 173 species; 2,632 belonging to 153 species in LF and 1,897 in 124 species in SF. Small fragments suffered a significant loss of bird richness, mainly forest dependent species, but the birds abundance did not decrease, due to an increase in abundance of forest independent and semi-dependent bird species (edge and non forest species) that benefit from forest fragmentation. The bird guilds of frugivores, undestory, terrestrial and midstory insectivores, nectarivores and raptors, and the endemic species of AF were area sensitive, decreasing significantly in richness and abundance in the SF. Terrestrial granivores were the only guild positively affected by forest fragmentation, containing mainly edge species, which forage in open areas or borders including crops. Our first observations on fragmentation effects on bird assemblages in the southernmost Argentinean Atlantic Forests did not validate the hypothesis on pre-adaptation to human disturbances in the bird communities of AF. On the contrary, we observed that forest dependent, endemic and several sensitive bird guilds were strongly affected by fragmentation, putting in evidence the vulnerability to the fragmentation process and the necessity to conserve large remnants to avoid reduction of the high biodiversity of AF birds.     

The importance of small scales to the fruit-feeding butterfly assemblages in a fragmented landscape

Nowadays 37% of Earth’s ice-free land is composed by fragments of natural habitats settled in anthropogenic biomes. Therefore, we have to improve our knowledge about distribution of organisms in remnants and to understand how the matrix affects these distributions. In this way, the present study aims to describe the structure of the butterfly assemblages and determined how richness and abundance are influenced by the scale of the surrounding vegetation. General linear models were used to investigate how the type and scale of vegetation cover within a radius of 100–2,000 m around the sampling point explained butterfly diversity. After sampling ten forest fragments we found 6,488 individuals of 73 species. For all clades tested null models explain the species richness at the fragments better than other models when we include the effect of butterfly abundance as a covariate. Abundance of Satyrini, Brassolini, and Biblidinae were best predicted by small scales (100–200 m), and large scales were more suited for Charaxinae. The presence of pasture best explains the abundance of all groups except Charaxinae, which was best explained by early-regrowth forest. The abundance of different species and groups are correlated with different kinds of vegetation cover. However, we demonstrate that small scales (100–200 m) are more effective at explaining the abundance of most butterflies. These results strongly suggest that efforts to preserve insect diversity in forest fragments should take in account the immediate surroundings of the fragment, and not only the regional landscape as a whole. In general, actions of people living near forest fragments are as important to fruit-feeding butterflies as large scale actions are, with the former being seldom specified in management plans or conservation policies.     

Effect of fragmentation on the community structure of epixylic bryophytes in Atlantic Forest remnants in the Northeast of Brazil

The effects of fragmentation and edge effects on the floristic composition, richness, diversity and abundance of epixylic bryophytes (growing on decaying wood) were investigated in ten fragments of Atlantic Forest remnants in the Northeast of Brazil. In each fragment, four perpendicular 100 m transects were demarcated. Along these transects, samples of bryophytes growing on decaying wood were collected. The forest fragments were grouped in three size classes (small: <100 ha; medium: 100–500 ha; large: >500 ha). Correlation and multivariate analysis were undertaken between bryophyte flora and fragment metrics (size, form, isolation, altitude variation, nuclear area and secondary vegetation percentage and distance from the edge). A total of 99 species of bryophytes, 52 liverworts and 47 mosses were registered. The statistical results confirming fragment size is an important factor in epixylic community structure. Therefore, composition, richness, diversity and abundance can be better explained by a junction of all studied landscape factors. Bryophyte richness, the percentage of samples with the greatest coverage of decaying wood and shade-tolerant species’ distribution, were not correlated to distance from the forest edge. This suggests that edge effects are not linear or can be detected beyond 100 m from the edge, which is very important for inclusion in future studies.     

Woody plant communities of isolated Afromontane cloud forests in Taita Hills,Kenya

In the Taita Hills in southern Kenya, remnants of the original Afromontane forest vegetation are restricted to isolated mountain peaks. To assess the level of degradation and the need for forest restoration, we examined how forest plant communities and their indicator species vary between and within remnant patches of cloud forest. We used ordinal abundance data to compare plant communities in eight forest fragments. We also analyzed data on the diversity and abundance of trees in 57 0.1 ha plots to compare tree communities within and between the largest two of these fragments, Ngangao (120 ha) and Mbololo (220 ha). The extant vegetation of the Taita Hills at landscape scale consists of secondary moist montane to intermediate montane forest. There was a high species dissimilarity between fragments (69%). Variation in species composition coincided with an abiotic gradient related to elevation. At plot level, secondary successional species and species of forest edges were most abundant and most frequent. Inferred clusters of plots almost entirely coincided with the two forest fragments. Indicator species associated with forest margins and gaps were more frequent in the smaller of the two forest fragments, while indicators for the larger fragment were more typical for less disturbed moist forest. Abiotic site variability but also different levels of disturbance determine site-specific variants of the montane forest. Conservation efforts should not only focus on maintaining forest quantity (size), but also on forest quality (species composition). Late-successional rainforest species are underrepresented in the woody plant communities of the Taita Hills and assisting restoration of viable populations of cloud forest climax tree species is urgently needed.     

The effects of urban or rural landscape context and distance from the edge on native woodland plant communities

The increasing rate of urban sprawl continues to fragment European landscapes threatening the persistence of native woodland plant communities. The dynamics of woodland edges depend on the characteristics of woodland patches and also on landscape context. Our aim was to assess the extent of edge influences on the understorey vegetation of small native woodlands in rural and urban landscapes. The study was carried out in two cities of north-western France. Ten comparable woodlands, each of about 1.5 ha, were surveyed; five were situated adjacent to crops and five adjacent to built-up land. Vascular plant species were recorded in 420 3 × 3 m plots placed at seven different distances from the edge (from 0 to about 45 m from the edge). Soil pH, light levels, level of disturbance and tree and shrub cover were also recorded. Plant species were first classified as non-indigenous or indigenous and then three groups of indigenous species were distinguished according to their affinity for forest habitat (forest specialists, forest generalists and non-forest species). We inferred certain ecological characteristics of understorey vegetation by using Ellenberg values. An inter-class correspondence analysis was carried out to detect patterns of variation in plant community composition. Linear mixed models were used to test the effects of adjacent land use, distance from the edge and their interactions on the species richness of the different groups and on the ecological characteristics of vegetation. Total species richness, richness of forest generalists and of non-forest species decreased from edge to interior in both urban and rural woodlands. The number of non-indigenous species depended mainly on urban–rural landscape context. Urban woodland edges were not as rich in forest specialists as rural edges. More surprisingly, the number of forest specialists was higher in rural edges than in rural interiors. Community composition was mainly affected by urban–rural context and to a lesser degree by the edge effect: the community composition of urban edges resembled that of urban interiors whereas in rural woodlands vegetation near edges (up to 10 m) strongly differed from interiors with a pool of species specific to edges. Urban woodland vegetation was more nitrophilous than rural vegetation in both edges and interiors. A major difference between urban and rural vegetation was the distribution of basiphilous species according to distance from the edge. Generally edge vegetation was more basiphilous than interior vegetation however the presence of basiphilous species fell off quickly with distance from the edge in rural woodlands (in the first 10–15 m) and more slowly (from 25 m onwards) in urban woodlands. This pattern was linked to variation in measured soil pH. As regards the conservation of flora in small native woodlands, it appeared that invasion of exotic and non-forest species was currently limited in both urban and rural landscape contexts but might pose problems in the future, especially in urban woodlands. Forest species were not negatively affected by the edge effect and indeed edges seemed to provide important habitats for this group. Hence conservationists should pay particular attention to the protection of edges in urban woodlands.     

Environmental and vegetation variables have a greater influence than habitat fragmentation in structuring lizard communities in remnant urban bushland

Abstract The expansion of urban areas and adjacent farming land into natural landscapes modifies habitats and produces small isolated pockets of native vegetation. This fragmentation of the natural habitat subdivides animal communities, reduces population sizes and increases vulnerability to extinction. In this paper we investigate whether fragmentation decreases lizard species richness, composition, overall abundance and abundance at the species level. Urban remnants consisting of five small (< 10 ha) and four large (> 10 ha) fragments of natural bushland were paired with continuous bushland areas located near Hobart, Tasmania, Australia. These remnants were surveyed six times, using pitfall traps, from November 2001 to March 2002. Lizard species richness and abundance were not significantly influenced by habitat fragmentation or fragment size. Egernia whitii was the only lizard species significantly influenced by fragment size, and was only present in large fragments and continuous bush. Vegetation type and structure as well as environmental variables (geology and aspect) influenced the structure of reptile communities. Lizard species that were able to use a number of different habitat types were found to persist at most sites, irrespective of fragment size. Edge environment did not significantly influence lizard species richness or abundance in remnant areas. Lizard species richness was significantly lower in sites that had a high ratio of exotic to native plant species. Therefore, if remnants continue to be invaded by exotic plants, lizard species that require native plant communities will become increasingly vulnerable to local extinction. Our results suggest that lizard species requiring specialized habitats, such as E. whitii, may persist in large urban remnants rather than small urban remnants because large reserves are more likely to encompass rare habitats, such as rocky outcrops. Habitat heterogeneity, rather than size, may be the key to their persistence.     

Butterfly Communities of Urban Forest Fragments in Campinas, São Paulo, Brazil: Structure, Instability, Environmental Correlates, and Conservation

A comparative study of butterfly communities in 15 urban/suburban remnants of tropical semideciduous forest in Campinas (São Paulo state, SE Brazil; 24°S, 47°W), with areas from 1.0 to 252ha and widely varying histories and environments, shows that the most significant factors, besides area and sampling time, distinguishing the sites and influencing their diversity (80–702 species) and composition are connectivity, permanent water, vegetation, flowers, and human impact (negative, including pollution). The diversified Nymphalidae butterflies (38–213 species) and especially two fermented-bait-attracted groups (Satyrinae, 2–30 species, and Biblidini, 9–44 species), are among the more useful indicators of the quality and diversity of the environments in these fragments. Effective conservation of butterfly communities in tropical cities may be achieved by maintenance of arboreal green corridors along streets and watercourses between moderately large (>10ha) humid areas, not near to the most built-up or polluted city centre(s), and the inclusion within these areas of ponds or streams, diversified native forest, and open vegetation including abundant nectar-rich flowers.     

Water availability determines the richness and density of fig trees within Brazilian semideciduous forest landscapes

The success of fig trees in tropical ecosystems is evidenced by the great diversity (+750 species) and wide geographic distribution of the genus. We assessed the contribution of environmental variables on the species richness and density of fig trees in fragments of seasonal semideciduous forest (SSF) in Brazil. We assessed 20 forest fragments in three regions in Sao Paulo State, Brazil. Fig tree richness and density was estimated in rectangular plots, comprising 31.4 ha sampled. Both richness and fig tree density were linearly modeled as function of variables representing (1) fragment metrics, (2) forest structure, and (3) landscape metrics expressing water drainage in the fragments. Model selection was performed by comparing the AIC values (Akaike Information Criterion) and the relative weight of each model (wAIC). Both species richness and fig tree density were better explained by the water availability in the fragment (meter of streams/ha): wAIC_richness = 0.45, wAIC_density = 0.96. The remaining variables related to anthropic perturbation and forest structure were of little weight in the models. The rainfall seasonality in SSF seems to select for both establishment strategies and morphological adaptations in the hemiepiphytic fig tree species. In the studied SSF, hemiepiphytes established at lower heights in their host trees than reported for fig trees in evergreen rainforests. Some hemiepiphytic fig species evolved superficial roots extending up to 100 m from their trunks, resulting in hectare-scale root zones that allow them to efficiently forage water and soil nutrients. The community of fig trees was robust to variation in forest structure and conservation level of SSF fragments, making this group of plants an important element for the functioning of seasonal tropical forests.     

Analysis of household's energy consumption,forest degradation and plantation requirements in Eastern Tigray,Northern Ethiopia

This study examines the link between household's energy consumption, forest degradation and plantation requirements in Eastern Tigray. Data on household's fuelwood, cow‐dung, kerosene and electricity consumption in the study sites were collected from 557 urban and 114 rural households. Deforestation rate was estimated following FAO and Woody Biomass Inventory Strategy Planning Project (WBISPP's) conversion factors. The study showed that household's fuelwood consumption in urban areas (mean = 2.5 kg/day) was about 52% lower as compared to the rural villages (mean = 3.8 kg/day). The estimated area abandoned annually in the vicinity of urban areas as the result of urban fuelwood consumption varies from 217 ha around Maichew town to 12047 ha around Mekelle City. The estimated area abandoned in rural areas annually as the result of tree cutting for fuelwood also varies from 6.5 ha around Sinkata to 127 ha around Dergajen village. It is therefore recommended that an estimated annual tree plantation of area ranging from 286 ha around Maichew town to 21,684 ha around Mekelle city is required. Moreover, an estimated annual tree plantation of area ranging from 16 ha around Sinkata village to 229 ha around the Dergajen village is required taking the existing population into account.     

Preservation of biodiversity in small rainforest patches: rapid evaluations using butterfly trapping

Determining the capacity of small forest remnants to support biodiversity is of critical importance, especially in the tropics where high rates of land conversion coincide with extraordinarily high species richness and endemism. Using fruit-baited traps, we conducted rapid evaluations in 1993 and 1994 of the forest butterfly diversity of seven small patches (3–30 ha) and a single remaining large patch (227 ha) of Costa Rican mid-elevation moist forest. Our results suggest that even recently isolated 20–30 ha fragments of primary forest retain surprisingly depauperate butterfly faunas relative to that supported by the 227 ha patch only 0.5–1.0 km away. If forest butterflies are an index of the diversity of small-bodied organisms in general, preservation of the latter may require unexpectedly large patches. In 1994 we also surveyed a 16 ha botanical garden, situated between and contiguous to both the 227 ha patch and an exceptionally species-rich 25 ha patch. In the garden, we discovered adults of many butterfly species associated with forest interior, suggesting that even heavily managed systems of largely exotic plants (such as agricultural systems) could be designed to serve as corridors for butterflies and perhaps some other groups of organisms. We discuss some implications for a planned restoration of biotic connections between lowland and montane forests in southern Costa Rica.     

Habitat loss effects on spatial distribution of non-vascular epiphytes in a Brazilian Atlantic forest

The vertical distribution of the richness, abundance, and composition of epiphytic bryophytes was studied in a matrix of fragmented habitats in the Brazilian Atlantic rainforest of the Murici Ecological Station (9°11′05″–9°16′48″ S, 35°45′20″–35°55′12″ W), northeastern Brazil. The aim was to compare the horizontal (between sites) and vertical (between phorophyte heights) turnover to test a hypothesis based on niche width vulnerability. There was a highly significant decreasing of richness accompanying the loss of habitat, and the most conserved fragment housed a total richness more than 10 times higher than the less conserved fragment. Epiphytes failed to colonize lower trunks (2.1–10 m) and higher zones in most of the non-conserved fragments; they were restricted to the base (0–2 m) and displayed a clear altered floristic composition. The species with restricted ecological amplitudes such as sun and shade tolerant taxa were more negatively affected by habitat loss than generalists. Although the mean richness of generalists decreased in non conserved fragments, the proportional contribution of this guild increased, proving that these taxa are the ones which persist in disturbed sites. The forest fragments capable of harboring rich epiphyte flora in the area studied are over 300 ha in size, which is far from being a common size among Brazilian Atlantic rainforest fragments. Hence, our results highlight the need of conserving the few large remnants in this ecosystem.     

Edge-Related Loss of Tree Phylogenetic Diversity in the Severely Fragmented Brazilian Atlantic Forest

Deforestation and forest fragmentation are known major causes of nonrandom extinction, but there is no information about their impact on the phylogenetic diversity of the remaining species assemblages. Using a large vegetation dataset from an old hyper-fragmented landscape in the Brazilian Atlantic rainforest we assess whether the local extirpation of tree species and functional impoverishment of tree assemblages reduce the phylogenetic diversity of the remaining tree assemblages. We detected a significant loss of tree phylogenetic diversity in forest edges, but not in core areas of small (<80 ha) forest fragments. This was attributed to a reduction of 11% in the average phylogenetic distance between any two randomly chosen individuals from forest edges; an increase of 17% in the average phylogenetic distance to closest non-conspecific relative for each individual in forest edges; and to the potential manifestation of late edge effects in the core areas of small forest remnants. We found no evidence supporting fragmentation-induced phylogenetic clustering or evenness. This could be explained by the low phylogenetic conservatism of key life-history traits corresponding to vulnerable species. Edge effects must be reduced to effectively protect tree phylogenetic diversity in the severely fragmented Brazilian Atlantic forest.     

Parasitoid phorid flies of leaf‐cutting ants are negatively affected by loss of forest cover

Habitat fragmentation can have a high impact on parasitoid–ant interactions. Phorid flies are among the most important groups of natural enemies of leaf‐cutting ants. We studied the effects of loss in forest cover upon phorids of the leaf‐cutting ant Acromyrmex nigerSmith (Hymenoptera: Formicidae: Attini) in a fragmented area in the Southeastern Atlantic Forest, Brazil. We sampled 10 forest fragments, five large (>75 ha) and five small (<20 ha), as well as three areas of continuous forest (>1 000 ha). We marked 1–5 colonies of A. niger in the interior of each forest location. At each nest, we collected all of the phorids in interaction with the worker ants for a period of 15 min. We then collected ca. 200 worker ants, which we maintained in the laboratory for rearing phorids from them. We identified three phorid genera – Apocephalus, Myrmosicarius, and Neodohrniphora – which we both observed in the field and reared in the laboratory. The abundance and parasitism percentage were significantly greater in continuous forest sites than in forest fragments, whereas there were no significant differences between fragments of different sizes. These results provide further evidence for the effects of habitat size on the phorid‐Acromyrmex system in a tropical rain forest, based on the abundance of parasitoids both as adults in the field and as reared immature phorids in the laboratory.     

Long-term impacts of grazing on indigenous forest remnants on North Island hill country, New Zealand

Small isolated patches of native forest surrounded by extensive pastoral grasslands, characteristic of many New Zealand rural landscapes, represent an important reservoir of lowland biodiversity. Improved management of them is a major focus of biodiversity conservation initiatives in New Zealand. We quantified the long-term impacts of grazing on indigenous forest remnants in hill country at Whatawhata, western Waikato, North Island. Structure and composition were compared between forest fragments grazed for >50 years and nearby ungrazed continuous forest. Grazed fragments had shorter and less shady canopies, sparser understoreys, tree populations with larger mean diameters, and ground layers with lower cover of litter and higher cover of vegetation and bare soil than continuous forest. Fragments also had lower indigenous-plant species richness, especially in sapling and seedling populations, and almost no palatable indigenous shrubs, terrestrial orchids, and ferns that require high humidity (e.g. Hymenophyllum spp.), but contained many indigenous and adventive herbaceous species. A transition appears to be occurring in grazed fragments from tall, long-lived trees like Beilschmiedia tawa and Dysoxylum spectabile to short and shorter-lived trees like Kunzea ericoides, Melicytus ramiflorus, and Dicksonia squarrosa. Because grazing inhibits most regeneration processes, unfenced remnants of conifer–broadleaved forest are unlikely to be maintained in grazed pasture in the long term.     

Nymphalid butterfly dispersal among forest fragments at Serra da Canastra National Park,Brazil

Organisms must possess good dispersal ability to persist in fragmented landscapes, as extinction in habitat patches is frequent and patches must be re-colonised to keep viable metapopulations. Thus, metapopulation maintenance is dependent on patch size and distance, although these affect species differently. In order to evaluate the ability of Nymphalid butterfly species to live in naturally fragmented small forest fragments we marked and released 3,415 butterflies in 16 of these areas separated in two networks at the Serra da Canastra National Park (PNSC), south-eastern Brazil. Subsequent recaptures in different forest fragments enabled us to assess the dispersal rates and distances for several Nymphalid species. Seventeen butterflies from 11 out of the 50 species captured were directly observed to disperse from 500 m to 870 m. Dispersal rates varied between 1 and 7% of the marked individuals and were directly correlated to the mean forewing length of each butterfly species population. The connectivity of the forest fragments through creeks appear to facilitate butterfly dispersal among fragments within micro-basins, as only one out of 50 dispersing individuals was observed to fly from one micro-basin to the other. Several species had viable populations in the small-fragment network. The distance between fragments is crucial as the coarser fragment network was unlikely to sustain viable populations of most of the species. The protection of large forest fragments located outside of the PNSC may be necessary to promote colonization of the smaller forest fragments inside the Park.     

Dung beetles in pasture landscapes of Central America: proliferation of synanthropogenic species and decline of forest specialists

This study examines the spread of synanthropogenic dung beetles (species favoured by human activities) in pasture landscapes in Central America, and evaluates the role of forest fragments and regenerating patches of native vegetation in maintaining beetle diversity. Pitfall trapping was carried out at nine locations in El Salvador and seven in Atlantic Nicaragua that included both pasture and remnant or regenerating native vegetation. More dung beetle species occurred in forest fragments than in pastures. Community composition differed considerably between forest fragments from El Salvador and Nicaragua with many species restricted to either the Caribbean or Pacific regions. In contrast, dung beetle community composition and structure were largely the same in the pastures of El Salvador and Nicaragua, regardless of region or original habitat-type, and were similar to published results from pastures in Mexico and elsewhere on the Isthmus. Very small patches of native shrubs and tree stands (<2.5 ha) maintained no forest specialists in Nicaragua, whereas, in El Salvador, some forest specialists occurred even in the smallest stands of trees (ca. 0.25 ha). The study indicates that the expansion of cattle pastures has caused a regional decline in dung beetle diversity. Forest fragments and small isolated patches of native trees and shrubs maintain some of the diversity of the original landscape but their conservation value for dung beetles will depend on the biogeographical history of the sites.     

Tree species diversity driven by environmental and anthropogenic factors in tropical dry forest fragments of central Veracruz, Mexico

We examined vegetation structure and woody species diversity in relation to 14 environmental and anthropogenic factors in ten tropical dry forest (TDF) fragments in central Veracruz, Mexico. The basal area of the canopy (30.2 ± 2.11 m²/ha) and understory (1.96 ± 0.12 m²/ha) trees was similar, but density (1,014 ± 104 and 2,532 ± 227 individuals/ha, respectively) differed among sites. We recorded 98 canopy, 77 understory, and 60 seedling species. Richness was 24–45 species per site, Fisher’s alpha and Shannon’s indices increased with site altitude. Chao Jaccard indices revealed high species turnover, and a consistently higher similarity within the sites at the lowest and within the highest elevation sites. Ordination identified altitude, aspect, slope, water proximity, cattle and trails as significant explanatory variables of species patterns, and showed that sites at lower elevations were clearly separated from the other sites. Environmental heterogeneity alone did not control species diversity distribution, but species were affected by environmental filters at different stages in their life cycle, e.g., water proximity was significant for saplings and seedlings but not for adults. Anthropogenic disturbances act synergistically, e.g., trails played a key role in determining structure and tree diversity patterns. An important finding is that human disturbance diminishes species diversity in this TDF, but sites at lower elevations were more disturbed and less diverse, therefore we need to study how environmental factors would act if there were no anthropogenic disturbance.     

Brewing trouble: coffee invasion in relation to edges and forest structure in tropical rainforest fragments of the Western Ghats, India

While the conservation impacts of invasive plant species on tropical biodiversity is widely recognised, little is known of the potential for cultivated crops turning invasive in tropical forest regions. In the Western Ghats biodiversity hotspot, India, fragmented rainforests often adjoin coffee plantations. This study in the Anamalai hills assessed the effects of distance from edges and forest structure on the occurrence and abundance of shade-tolerant coffee (Arabica Coffea arabica and Robusta C. canephora) in four fragments (32–200 ha) using replicate line transects laid from the edges into the interiors. The coffee species cultivated in adjoining plantations was more abundant than the other coffee species inside study fragments, showing a clear decline in stem density from edge (0 m) to interior (250 m), suggesting the influence of propagule pressure of adjoining plantations, coupled with edge effects and seed dispersal by animals. Significant positive correlations of coffee density with canopy cover indicate the potential threat of coffee invasion even in closed canopy rainforests. Stem density of Coffea arabica (150–1,825 stems/ha) was higher in more disturbed fragments, whereas Coffea canephora had spread in disturbed and undisturbed sites achieving much higher densities (6.3–11,486 stems/ha). In addition, a negative relationship between C. canephora and native shrub density indicates its potential detrimental effects on native plants.     

Can agroforest woodlots work as stepping stones for birds in the Atlantic forest region?

In fragmented landscapes, agroforest woodlots can potentially act as stepping stones facilitating movement between forest fragments. We assessed the influence of agroforest woodlots on bird distribution and diversity in the Atlantic forest region (SE Brazil), and also tested which categories of species can use different types of connection elements, and whether this use is influenced by the distance to large forest patches. We studied two fragmented landscapes, with and without stepping stones linking large fragments, and one forested landscape. Using a point count, a bird survey was undertaken in the fragmented landscapes in five different elements: large remnants (>400 ha), agroforest woodlots (0.4–1.1 ha), small patches (0.5–7 ha), riparian corridor, and pasture areas (the main matrix). Generalist and open-area species were commonly observed in the agroforest system or other connection elements, whereas only a few forest species were present in these connections. For the latter species, the distance of woodlots to large patches was essential to determine their richness and abundance. Based on our results and data from literature, we suggest that there is an optimal relationship between the permeability of the matrix and the efficiency of stepping stones, which occurs at intermediate degrees of matrix resistance, and is species-dependent. Because the presence of agroforest system favors a higher richness of generalist species, they appeared to be more advantageous for conservation than the monoculture system; for this reason, they should be considered as a management alternative, particularly when the matrix permeability requirement is met.