Diazotrophs Show Signs of Restoration in Amazon Rain Forest Soils with Ecosystem Rehabilitation.

Biological nitrogen fixation can be an important source of nitrogen in tropical forests that serve as a major CO2 sink. Extensive deforestation of the Amazon is known to influence microbial communities and the biogeochemical cycles they mediate. However, it is unknown how diazotrophs (nitrogen-fixing microorganisms) respond to deforestation and subsequent ecosystem conversion to agriculture, as well as whether they can recover in secondary forests that are established after agriculture is abandoned. To address these knowledge gaps, we combined a spatially explicit sampling approach with high-throughput sequencing of nifH genes. The main objectives were to assess the functional distance decay relationship of the diazotrophic bacterial community in a tropical forest ecosystem and to quantify the roles of various factors that drive the observed changes in the diazotrophic community structure. We observed an increase in local diazotrophic diversity (α-diversity) with a decrease in community turnover (β-diversity), associated with a shift in diazotrophic community structure as a result of the forest-to-pasture conversion. Both diazotrophic community turnover and structure showed signs of recovery in secondary forests. Changes in the diazotrophic community were primarily driven by the change in land use rather than differences in geochemical characteristics or geographic distances. The diazotroph communities in secondary forests resembled those in primary forests, suggesting that at least partial recovery of diazotrophs is possible following agricultural abandonment.IMPORTANCE The Amazon region is a major tropical forest region that is being deforested at an alarming rate to create space for cattle ranching and agriculture. Diazotrophs (nitrogen-fixing microorganisms) play an important role in supplying soil N for plant growth in tropical forests. It is unknown how diazotrophs respond to deforestation and whether they can recover in secondary forests that establish after agriculture is abandoned. Using high-throughput sequencing of nifH genes, we characterized the response of diazotrophs' β-diversity and identified major drivers of changes in diazotrophs from forest-to-pasture and pasture-to-secondary-forest conversions. Studying the impact of land use change on diazotrophs is important for a better understanding of the impact of deforestation on tropical forest ecosystem functioning, and our results on the potential recovery of diazotrophs in secondary forests imply the possible restoration of ecosystem functions in secondary forests

Increasing turnover through time in tropical forests

Tree turnover rates were assessed at 40 tropical forest sites. Averaged across inventoried forests, turnover, as measured by tree mortality and recruitment, has increased since the 1950's, with an apparent pantropical acceleration since 1980. Among 22 mature forest sites with two or more inventory periods, forest turnover also increased. The trend in forest dynamics may have profound effects on biological diversity

Temporal variation in abundance and diversity of butterflies in Bornean rain forests: opposite impacts of logging recorded in different seasons

We used traps baited with fruit to examine how the temporal variation of butterflies within primary forest in Sabah, Borneo differed between species. In addition, we compared patterns of temporal variation in primary and selectively logged forest, and we tested the hypothesis that selective logging has different recorded impacts on species diversity of adults during the wet monsoon period and the drier remaining half of the year. Species of Satyrinae and Morphinae had significantly less-restricted flight periods than did species of Nymphalinae and Charaxinae, which were sampled mainly during the drier season. especially in primary forest. Species diversity of adults was significantly higher during the drier season in primary forest, but did not differ between seasons in logged forest. As a consequence, logging had opposite recorded impacts on diversity during wetter and drier seasons: primary forest had significantly higher diversity than logged forest during the drier season but significantly lower diversity than logged forest during the wetter monsoon season. The results of this study have important implications for the assessment of biodiversity in tropical rain forests, particularly in relation to habitat disturbance: short-term assessments that do not take account of seasonal variation in abundance are likely to produce misleading results, even in regions where the seasonal variation in rainfall is not that great

Tropical forest remnants as shelters of avian diversity within a tourism development matrix in Yucatan Peninsula, Mexico

Tropical forests have undergone extensive transformation because of increasing tourism development, in addition to historic clearing for agricultural and cattle grazing activities. Altogether, these activities have had an important effect on bird diversity, reducing the habitat available to many species. In this study, the role of tropical forest remnants located between different land use types was evaluated for species diversity, composition, and distribution of the bird community at Akumal region in Quintana Roo, Mexico. Point counts were used to quantify the avifauna by habitat, and Shannon´s and Simpson´s diversity index were used to determine bird diversity. Additionally, bird species were classified according to seasonality and trophic guild by type of habitat. A total of 160 species and 50 families was recorded, of which 100 species were permanent residents, 47 winter visitors and 11 transients. Mature tropical forest and tropical forest remnants had higher species richness than those of modified environments. This study supports the importance of tropical forest remnants as shelters for bird species in landscapes with tourism developments, and the relevance of these remnants to maintaining high bird diversity

Tree species diversity, distribution and population structure in a tropical dry deciduous forests of Chhatisgarh, India

Tree species diversity, distribution and population structure of tropical forests of Bharnawapara wildlife sanctuary was investigated. The study analyzed the structure of a tropical dry deciduous forest in Chhatisgarh at different sites i.e. closed natural forest, open natural forest and plantation forests of teak. The study was conducted by laying 30 quadrats, each 10 m × 10 m in size at different sites. In total, 246 trees belonging to 28 species of 17 families were recorded from 0.3 ha sampling area. Density ranged between 520 to 990 trees ha-1 subsequently, basal area ranged between 21.50 to 47.30 m2 ha-1. The dominant tree species was Cleistanthus collinus with an importance value index (IVI) of 57.70. Other important species were Terminalia tometosa (IVI 47.10), Lagerstroemia parviflora (36.92), Diospyros melanoxylon (28.42) and Madhuca indica(26.03). The Shannon-Wiener index (H?) ranged between 0.19 to 3.35 and Simpson’s index (C) between 0.12 to 0.95 indicating high tree species diversity of tropical dry deciduous forests. It is evident from the study that natural forest has an edge over plantation forest in terms of species diversity, dominance and richness. Tree species diversity, distribution and population structure provide baseline information for conservation and management of tropical dry deciduous forests in India. Efforts are needed to conserve the natural forest for their diversity and existence. They can also be supplemented with plantation forests to lower the biotic pressure

Distinctive soil archaeal communities in different variants of tropical equatorial forest

Little is known of how soil archaeal community composition and diversity differ between local variants of tropical rainforests. We hypothesized that (1) as with plants, animals, fungi, and bacteria, the soil archaeal community would differ between different variants of tropical forest; (2) that spatially rarer forest variants would have a less diverse archaeal community than common ones; (3) that a history of forest disturbance would decrease archaeal alpha- and beta-diversity; and (4) that archaeal distributions within the forest would be governed more by deterministic than stochastic factors. We sampled soil across several different forest types within Brunei, Northwest Borneo. Soil DNA was extracted, and the 16S rRNA gene of archaea was sequenced using Illumina MiSeq. We found that (1) as hypothesized, there are distinct archaeal communities for each forest type, and community composition significantly correlates with soil parameters including pH, organic matter, and available phosphorous. (2) As hypothesized, the “rare” white sand forest variants kerangas and inland heath had lower archaeal diversity. A nestedness analysis showed that archaeal community in inland heath and kerangas was mainly a less diverse subset of that in dipterocarp forests. However, primary dipterocarp forest had the lowest beta-diversity among the other tropical forest types. (3) Also, as predicted, forest disturbance resulted in lower archaeal alpha-diversity—but increased beta-diversity in contrast with our predictions. (4) Contrary to our predictions, the BetaNTI of the various primary forest types indicated community assembly was mainly stochastic. The possible effects of these habitat and disturbance-related effects on N cycling should be investigated

Diversity of Soil Macro Insect in Alas Purwo National Park, Banyuwangi, East Java, Indonesia

Indonesia is the second largest mega biodiversity of the world. One of the forest resources are soil insects. Soil insects improved the soil physical properties, added organic material content, and used as bio-indicator of environmental conditions of conservation areas, forests, or mountains. The aim of this research was to get information about the diversity, dominance, and similarity index of soil macro insect in Alas Purwo National Park, Banyuwangi, East Java, Indonesia in 2017. Locations were selected based on purposive random sampling considering 2 habitat types; coastal forest path and tropical rain forest path. The method of this research was used pitfall trap. Insects were identified at Laboratory of Ecology, Biology Department, Faculty of Science and Technology, Airlangga University, Surabaya. The results showed that the diversity index of soil insects in the coastal forest path was 1.611 and in path of tropical rain forest was 0.855. It means that the diversity of soil macro insect in coastal forest path were medium and in path of tropical rain forest was low. The Dominancy index of coastal forest path was 0.334 and in path of tropical rain forest was 0.433. It means that the community was stable, there was no species domination. The similarity index of soil insects in both paths have a 58.8%, was a unity of the same community

Bee diversity responses to forest and open areas in heterogeneous Atlantic Forest

Agriculture driven landscape changes has caused worldwide forest loss and fragmentation, seriously affecting biodiversity and ecosystem services, amongst which pollination is remarkably important. Bees are an essential pollinator group for forest plant populations and food production in tropical landscapes. They are also dependent on forested environments which are essential to maintain their diversity and pollination services. We analyzed bee diversity in contrasting forest and adjacent non-forest patches to evaluate if bees can use complementary non-native environments in heterogeneous altered tropical landscapes. The effect of landscape level heterogeneity and forest amount on bee diversity was also assessed. Our hypothesis was that bee communities would be more rich and diverse inside the forest understory, but due to supplementary foraging behaviors they would be more abundant in non-forested areas where flower availability is higher. We actively sampled bees visiting flowers within forest patches and in surrounding non-forest open areas between the Cantareira and Mantiqueira mountain ranges in São Paulo, Brazil. We found higher bee richness and diversity in open areas than in forest patches, partially denying our initial hypothesis but supporting that bees are more abundant in non-forest areas. We found strong indication that landscapes with higher amount of forest and environmental heterogeneity can provide more resources for bees through resource complementation processes, maintaining their diversity in the landscape. The presence of forest patches close to crop and open areas is of utmost importance for the conservation of bees and pollination services with important consequences for land management in tropical environments