Drivers of Fungal Succession in Three Different Woody Species in a Tropical Forest Fragment

Riparian corridors and fencerows are hypothesized to increase the persistence of forest animals in fragmented landscapes by facilitating movement among suitable habitat patches. This function may be critically important for forest birds, which have declined dramatically in fragmented habitats. Unfortunately, direct evidence of corridor use has been difficult to collect at landscape scales and this limits support for corridors in conservation planning. Using telemetry and handheld GPS units, we examined the movement of forest birds by translocating territorial individuals of barred antshrikes (Thamnophilus doliatus; a forest specialist) and rufous-naped wrens (Campylorhynchus rufinucha; a forest generalist) 0.7-1.9 km from their territories in the highly fragmented tropical dry forest of Costa Rica. In each translocation, the directly intervening habitat comprised 1 of 3 treatments: forested riparian corridor, linear living fencerow, or open pasture. Antshrikes returned faster and with greater success in riparian corridors relative to pasture treatments. This species also traveled more directly in riparian corridor treatments, detoured to use forested routes in the other 2 treatments, and did not use fencerows even when they led directly to their home territories. By contrast, wrens were more likely to use fencerows when returning, and return time and success were equivalent among the 3 treatments. Both species crossed fewer gaps in tree cover during riparian corridor treatments than in fencerow or pasture treatments. We conclude that antshrikes, which may be representative of other forest specialists, use forested corridors for movement in this landscape and that fencerows are avoided as movement conduits.

Foram realizados o levantamento florístico e a classificação em grupos de síndromes de dispersão e de sucessão ecológica das espécies lenhosas ocorrentes em um fragmento florestal de 1,14ha, localizado em de Campos do Jordão, SP. O levantamento florístico registrou 54 espécies lenhosas pertencentes a 43 gêneros de 33 famílias ocorrente na borda, no interior e em ambos os hábitats do remanescente
 florestal. Prevaleceu uma maior proporção de espécies zoocóricas (31,4%), ocorrendo espécies anemocóricas (23,5%) e autocóricas (3,9%), indicando uma proporção
 comum às florestas tropicais. A classificação sucessional indicou o predomínio de espécies secundárias (44%), seguido pelas pioneiras (18%), além de diversas espécies sem caracterização (38%) devido à carência de informações a respeito de suas estratégias de regeneração. Possivelmente os impactos negativos do processo de fragmentação atuante na região foram, provavelmente, os fatores determinantes para o empobrecimento florístico e a descaracterização de sua fitofisionomia original de Floresta Ombrófila Mista Alto Montana que se encontra em estágio intermediário de
 regeneração. Apesar do baixo número de espécies registradas na área, esse fragmento pode ser de grande importância para a sustentabilidade dos remanescentes vizinhos se comprovado seu papel na conectividade funcional da paisagem. Nesse remanescente florestal, ainda podem ser encontradas espécies arbustivas e arbóreas comuns às
 formações florestais estacionais e mistas de altitude, que demonstram sua função de manutenção da ameaçada biodiversidade regional.

A first analysis of the stability of trophic structure following tropical forest fragmentation was performed in an experimentally fragmented tropical forest landscape in Central Amazonia. A taxonomically and trophically diverse assemblage of 993 species of beetles was sampled from 920 m 2 of leaf litter at 46 sites varying in distance from forest edge and fragment area. Beetle density increased significantly towards the forest edge and showed non-linear changes with fragment area, due to the influx of numerous disturbed-area species into 10 ha and 1 ha fragments. There was a marked change in species composition with both decreasing distance from forest edge and decreasing fragment area, but surprisingly this change in composition was not accompanied by a change in species richness. Rarefied species richness did not vary significantly across any of the sites, indicating that local extinctions of deep forest species were balanced by equivalent colonization rates of disturbed-area species. The change in species composition with fragmentation was non-random across trophic groups. Proportions of predator species and xylophage species changed significantly with distance from forest edge, but no area-dependent changes in proportions of species in trophic groups were observed. Trophic structure was also analysed with respect to proportions of abundance in six trophic groups. Proportions of abundance of all trophic groups except xylomycetophages changed markedly with respect to both distance from forest edge and fragment area. Local extinction probabilities calculated for individual beetle species supported theoretical predictions of the differential susceptibility of higher trophic levels to extinction, and of changes in trophic structure following forest fragmentation. To reduce random effects due to sampling error, only abundant species ( n ≥ 46) were analysed for extinction probabilities, as defined by absence from samples. Of these common species, 27% had significantly higher probabilities of local extinction following fragmentation. The majority of these species were predators; 42% of all abundant predator species were significantly more likely to be absent from samples in forest fragments than in undisturbed forest. These figures are regarded as minimum estimates for the entire beetle assemblage because rarer species will inevitably have higher extinction probabilities. Absolute loss of biodiversity will affect ecosystem process rates, but the differential loss of species from trophic groups will have an even greater destabilizing effect on food web structure and ecosystem function.

Towards rapid assessments of tree species diversity and structure in fragmented tropical forests: A review of perspectives offered by remotely-sensed and field-based data

Few data exist on seed dispersal by frugivorous birds in fragmented landscapes, originating from tropical dry forests, in contrast to more abundant data from tropical rain forests. In this study, we assessed the effect of frugivorous birds in a fragmented landscape of Veracruz, Mexico, now occupied by remnant fragments of tropical semi-deciduous forest and dry deciduous forest, grassland, and shrubby patches on sand dunes. We determined four characteristics related to seed dispersal by birds: the interacting species of plants and birds, the characteristics of these species, spatio-temporal variation in the dispersal system, and the outcome of the process. During one year, we recorded 54 frugivorous bird species and 33 ornithochorous plant species, which engaged in 176 different bird–plant species interactions. Similarity (Sørensen index) of frugivorous bird communities using different vegetation types was high (>70%), suggesting that many bird species used all of the vegetation types. In contrast, the similarity of ornithochorous plant communities among vegetation types commonly was low (<37%), suggesting that most plant species were restricted to particular sites in this landscape. At the landscape level, as well as for tropical deciduous forest, we detected a significant positive relationship (Spearman's correlation of rank coefficient >0.65, P < 0.05) among richness per month of frugivorous birds and plant species bearing fleshy fruits. Seeds of many plant species previously detected in studies of seed rain at the site were eaten by birds during this study. Most seeds of zoochorous species, which are deposited in the dry and decidous tropical forests patches, are produced within these vegetation types (i.e., they are autochthonous species), whereas bird-dispersed seeds arriving in grassland and shrubby patches are produced outside (i.e., allochthonous) and are mostly woody species. Birds are important seed dispersers among vegetation types in this landscape but they have different effects in each one. The four characteristics studied, as well as the landscape approach of this research, allowed us to detect spatial and temporal patterns that otherwise would have remained undetected.

Bats are hosts of a high taxonomic diversity of ectoparasites. Six hundred eighty seven insect species have been reported as bat ectoparasites, belonging to orders Dermaptera, Lepidoptera, Diptera and Siphonaptera (Marshall 1982). This study lists an inventory of bat ectoparasites found in fragments of Tropical Dry Forest on the Caribbean coast of Colombia. The study was conducted in the Department of Cordoba in four farms with fragments of Tropical Dry Forest. Bats were captured using mist nets and were collected and stored in plastic bags for subsequent examination in the laboratory. Ectoparasites were stored in alcohol and identified using a stereo microscope and taxonomic keys. Two hundred fifty one bats belonging to 21 species were captured. The most abundant family was Phyllostomidae, followed by Emballonuridae, Noctilionidae, Vespertilionidae and Molossidae. Twelve genera of ectoparasites were found, belonging to families Streblidae, Nycteribiidae and Polyctenidae. Streblidae was the most abundant family and included the largest number of species. Thirty five percent of bats examined were hosts to at least one ectoparasite species. In this study, carried out in fragments of tropical dry forest in Cordoba, Colombia, we recorded dipterans in 17 out of 21 bat species. Hemypteran ectoparasites of the family Polyctenidae were found in Molossus molossus only. Eighty seven individual dipterans were found among 51 Carollia perspicillata specimens, which is consistent with the high parasitism levels previously reported. The bat species C. brevicauda, P. discolor, U. bilobatum and C. perspicillata carried the highest number of ectoparasite species.

Fragmentation drives tropical forest fragments to early successional states: A modelling study for Brazilian Atlantic forests

Tropical forest fragmentation results in habitat and biodiversity loss and increased carbon emissions. Here, we link an increased likelihood of tropical forest loss to decreasing fragment size, particularly in primary forests. The relationship holds for protected areas, albeit with half the rate of loss compared with all fragments. The fact that disturbance increases as primary forest fragment size decreases reflects higher land use pressures and improved access for resource extraction and/or conversion in smaller fragments. Large remaining forest fragments are found in the Amazon and Congo Basins and Insular Southeast Asia, with the majority of large extent/low loss fragments located in the Amazon. Tropical areas without large fragments, including Central America, West Africa, and mainland Southeast Asia, have higher loss within and outside of protected areas. Results illustrate the need for rigorous land use planning, management, and enforcement in maintaining large tropical forest fragments and restoring regions of advanced fragmentation.

Abstract: Tropical forests are becoming increasingly fragmented, threatening the survival of the species that depend on them. Small, isolated forest fragments will lose some of their original species. What is uncertain is how long this process of faunal relaxation will take. We compiled data on birds in five tropical forest fragments in Kakamega Forest, Kenya, of known date of isolation. We then predicted the original and eventual species richness of these fragments and, from this difference, the eventual species losses. Expressing the losses to date as a fraction of eventual losses suggests that faunal relaxation approximates an exponential decay with a half‐life of approximately 50 years for fragments of roughly 1000 ha. In other words, in the first 50 years after isolation, tropical forest fragments of this size suffer half of the total number of extinctions that they are likely to experience. This result sets the time scale over which humanity must take conservation action in fragmented tropical forests, may aid efforts to set priorities, and indicates how high the future global extinction rate will be.

Area use by white-lipped and collared peccaries ( Tayassu pecari and Tayassu tajacu) in a tropical forest fragment

Landscape-level impact of tropical forest loss and fragmentation on bird occurrence in eastern Guatemala

Lessons in ecology and conservation from a tropical forest fragment in Singapore

Introduction Tropical rainforests are renowned for their ecological complexity and the seeming ubiquity of coevolved relationships among species (Janzen 1969; Gilbert 1980). Unfortunately, these forests are being destroyed and fragmented at alarming rates, to the extent that many tropical protected areas are becoming virtual islands in a sea of heavily degraded land (Laurance & Bierregaard 1997; DeFries et al . 2002). The future of tropical biodiversity will be largely determined by the extent to which natural ecological processes and communities can be maintained in isolated fragments of forest. Here I summarize available information on the alteration of biotic interactions, such as predation and key symbioses like pollination and seed dispersal, in fragmented tropical forests. This review is necessarily preliminary, given the great diversity of species and ecological interactions in the tropics and the fact that the alteration of biotic linkages is among the most poorly understood consequences of habitat fragmentation. Initial impacts of fragmentation Forest fragmentation leads to the reduction and isolation of remnant forest patches. Although each fragmented landscape is unique, a common pattern is that most forest fragments in human-dominated landscapes are small, ranging in size from a hectare or less to a few hundred hectares (Gascon et al . 2000; Cochrane & Laurance 2002). The biota of such small forest patches are expected to be vulnerable to edge effects and many other negative consequences of fragmentation (e.g. Laurance et al . 1998, 2002).

Amazonian rainforests sustain some of the richest tree communities on Earth, but their ecological and evolutionary responses to human threats remain poorly known. We used one of the largest experimental datasets currently available on tree dynamics in fragmented tropical forests and a recent phylogeny of angiosperms to test whether tree communities have lost phylogenetic diversity since their isolation about two decades previously. Our findings revealed an overall trend toward phylogenetic impoverishment across the experimentally fragmented landscape, irrespective of whether tree communities were in 1-ha, 10-ha, or 100-ha forest fragments, near forest edges, or in continuous forest. The magnitude of the phylogenetic diversity loss was low (<2% relative to before-fragmentation values) but widespread throughout the study landscape, occurring in 32 of 40 1-ha plots. Consistent with this loss in phylogenetic diversity, we observed a significant decrease of 50% in phylogenetic dispersion since forest isolation, irrespective of plot location. Analyses based on tree genera that have significantly increased (28 genera) or declined (31 genera) in abundance and basal area in the landscape revealed that increasing genera are more phylogenetically related than decreasing ones. Also, the loss of phylogenetic diversity was greater in tree communities where increasing genera proliferated and decreasing genera reduced their importance values, suggesting that this taxonomic replacement is partially underlying the phylogenetic impoverishment at the landscape scale. This finding has clear implications for the current debate about the role human-modified landscapes play in sustaining biodiversity persistence and key ecosystem services, such as carbon storage. Although the generalization of our findings to other fragmented tropical forests is uncertain, it could negatively affect ecosystem productivity and stability and have broader impacts on coevolved organisms.

Abstract: The tropical dry forest is under constant threat from many anthropic activities which are conducted indiscriminately, modifying the forest, and therefore, affecting species that are closely related to its phenology, such as longhorned beetles (Cerambycidae). The spatio-temporal variation of the cerambycid diversity in two fragments of tropical dry forest (Reserva Campesina la Montaña and La Flecha) in the Caribbean region of Colombia was analyzed. At each locality, four squared plots were delimited, and the beetles were collected with fruit traps, beating sheets and manual capture, and with light traps in the center. Five hundred eighty-seven specimens representing 128 species were collected, of which members of the tribe Ectenessini (Cerambycinae) were the most abundant. At the subfamily level, Cerambycinae was the most abundant (465 specimens) and diverse (73 species), followed by Lamiinae and Prioninae. The highest values of richness (110 species), abundance (428), biomass (21.18 g), and as well as the highest values of true diversity (1D= 73.44, 2D= 34.30) were found during the first precipitations. Regarding beta diversity, temporal variation was determined and mainly explained by a high percentage of turnover (&gt; 70%). Lastly, the high diversity of Cerambycidae was associated with high values of relative humidity and canopy cover during the rainy season. This showed that the structure of the cerambycid community in the tropical dry forest of the Caribbean region of Colombia depends on these variables, which are closely related to precipitation.