Parallel functional and stoichiometric trait shifts in South American and African forest communities with elevation

The Amazon and Congo basins are the two largest continuous blocks of tropical forest with a central role for global biogeochemical cycles and ecology. However, both biomes differ in structure and species richness and composition. Understanding future directions of the response of both biomes to environmental change is paramount. We used one elevational gradient on both continents to investigate functional and stoichiometric trait shifts of tropical forest in South America and Africa. We measured community-weighted functional canopy traits and canopy and topsoil delta N-15 signatures. We found that the functional forest composition response along both transects was parallel, with a shift towards more nitrogen-conservative species at higher elevations. Moreover, canopy and topsoil delta N-15 signals decreased with increasing altitude, suggesting a more conservative N cycle at higher elevations. This cross-continental study provides empirical indications that both South American and African tropical forest show a parallel response with altitude, driven by nitrogen availability along the elevational gradients, which in turn induces a shift in the functional forest composition. More standardized research, and more research on other elevational gradients is needed to confirm our observations

Landscape context mediates the relationship between plant functional traits and decomposition

Aims: It has been well demonstrated that several interacting endogenous and exogenous factors influence decomposition. However, teasing apart the direct and indirect effects of these factors to predict decomposition patterns in heterogenous landscapes remains a key challenge. Methods: At 157 locations in a temperate forest, we measured decomposition of a standard substrate (filter paper) over two years, the landscape context in which decomposition took place, and the functional composition of the woody species that contributed leaf litter to the forest floor where litter bags were placed. We tested for direct and indirect effects of landscape context and direct effects of forest functional composition on decay using structural equation modelling. Results: We found that landscape context had direct effects on decay and indirect effects on decay via its influence on the functional composition of the surrounding forest. Forest functional composition also had direct effects on decay, but these effects decreased or disappeared completely over time. Moreover, community weighted mean trait values were better predictors of decay than functional dispersion of leaf traits, and leaf nitrogen content and carbon content were better predictors of decay than leaf dry matter content or leaf toughness. Conclusions: Our results highlight the importance of an integrative approach that examines the direct and indirect effects of multiple factors for understanding and predicting decomposition patterns across heterogenous landscapes

Marked decline in forest-dependent small mammals following habitat loss and fragmentation in an Amazonian deforestation frontier

Agricultural frontier expansion into the Amazon over the last four decades has created million hectares of fragmented forests. While many species undergo local extinctions within remaining forest patches, this may be compensated by native species from neighbouring open-habitat areas potentially invading these patches, particularly as forest habitats become increasingly degraded. Here, we examine the effects of habitat loss, fragmentation and degradation on small mammal assemblages in a southern Amazonian deforestation frontier, while accounting for species-specific degree of forest-dependency. We surveyed small mammals at three continuous forest sites and 19 forest patches of different sizes and degrees of isolation. We further sampled matrix habitats adjacent to forest patches, which allowed us to classify each species according to forest-dependency and generate a community-averaged forest-dependency index for each site. Based on 21,568 trap-nights, we recorded 970 small mammals representing 20 species: 12 forest-dependents, 5 matrix-tolerants and 3 open-habitat specialists. Across the gradient of forest patch size, small mammal assemblages failed to show the typical species-area relationship, but this relationship held true when either species abundance or composition was considered. Species composition was further mediated by community-averaged forest-dependency, so that smaller forest patches were occupied by a lower proportion of forest-dependent rodents and marsupials. Both species richness and abundance increased in less isolated fragments surrounded by structurally simplified matrix habitats (e.g. active or abandoned cattle pastures). While shorter distances between forest patches may favour small mammal abundances, forest area and matrix complexity dictated which species could persist within forest fragments according to their degree of forest-dependency. Small mammal local extinctions in small forest patches within Amazonian deforestation frontiers are therefore likely offset by the incursion of open-habitat species. To preclude the dominance of those species, and consequent losses of native species and associated ecosystem functions, management actions should limit or reduce areas dedicated to pasture, additionally maintaining more structurally complex matrix habitats across fragmented landscapes

Habitat Associations of Macro-Staphylinids (Coleoptera: Staphylinidae) at Alice L. Kibbe Life Science Station, Hancock County, Illinois

Habitat associations of size-selected (≥ 5 mm length) rove beetles (Coleoptera: Staphylinidae), hereafter referred to as “macro-staphylinids,” were studied in west-central Illinois forest and prairie habitats in 2005 using pitfall traps. Habitats sampled included oak-hickory forest last burned in spring 2004, oak-hickory forest burned in spring 2005, oak-hickory forest unburned for 5+ years, unburned early successional forest, reconstructed prairie last burned in spring 2004, and reconstructed prairie burned in spring 2005. A total of 361 macrostaphylinids, representing 12 species, were collected, with Philonthus caerulipennis (Mannerheim), Platydracus maculosus (Gravenhorst), Platydracus fossator Gravenhorst, Platydracus zonatus (Gravenhorst), and Tachinus fimbriatus Gravenhorst comprising 94% of all macro-staphylinids collected. Fewest numbers of macro-staphylinids were collected in prairie habitats, particularly the prairie burned in spring 2005. A multi-response permutation procedure revealed significant variation in species composition among habitats, with relatively large differences between burned and unburned forest habitats and between forest and prairie habitats. Within-habitat variation in species composition was relatively high in the prairie and recently burned forest habitats. Indicator species analysis revealed a significant association of Philonthus asper Horn with the early successional forest, and four species had relatively high indicator values for multiple forest habitats, with fire playing a potentially important role in some cases. More intensive sampling and larger sample sizes are needed to clarify these potential habitat associations

Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient

We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

A comparison of presettlement and modern forest composition along an elevation gradient in central New Hampshire

Tree species composition is influenced not only by edaphic and climatic factors but also by natural and human-caused disturbances. To understand interactions among these influences, we compared forest species composition data from the time of European settlement with modern data. We derived elevation data for 2529 trees mapped by early land surveys (1770–1850) across a 1000 m elevation gradient in central New Hampshire and compared these with modern data (2004–2009) from the Forest Inventory and Analysis program (123 plots containing 2126 trees) and from permanent plots representing case studies of different land-use histories. Spruce and beech are much less abundant today at all elevations than they were prior to settlement, while maples and birches have increased. Fir, hemlock, pines, and oaks have changed little in distribution, although pines and oaks increased in abundance somewhat. Land-use history (agriculture below 500 m and cutting of various intensities at all elevations) is likely the primary explanation for these shifts, although climate change is also an important factor for some. A clearer understanding of presettlement forest composition improves our ability to separate the relative importance of natural and human-driven influences on the species composition of today’s forests

Does degradation from selective logging and illegal activities differently impact forest resources? A case study in Ghana

Degradation, a reduction of the ecosystem’s capacity to supply goods and services, is widespread in tropical forests and mainly caused by human disturbance. To maintain the full range of forest ecosystem services and support the development of effective conservation policies, we must understand the overall impact of degradation on different forest resources. This research investigates the response to disturbance of forest structure using several indicators: soil carbon content, arboreal richness and biodiversity, functional composition (guild and wood density), and productivity. We drew upon large field and remote sensing datasets from different forest types in Ghana, characterized by varied protection status, to investigate impacts of selective logging, and of illegal land use and resources extraction, which are the main disturbance causes in West Africa. Results indicate that functional composition and the overall number of species are less affected by degradation, while forest structure, soil carbon content and species abundance are seriously impacted, with resources distribution reflecting the protection level of the areas. Remote sensing analysis showed an increase in productivity in the last three decades, with higher resiliency to change in drier forest types, and stronger productivity correlation with solar radiation in the short dry season. The study region is affected by growing anthropogenic pressure on natural resources and by an increased climate variability: possible interactions of disturbance with climate are also discussed, together with the urgency to reduce degradation in order to preserve the full range of ecosystem functions

Changes in the silver fir forest vegetation 50 years after cessation of active management

Knowledge of the vegetation and the monitoring of its changes in preserved areas is an essential part of effective conservation policy and management. The aim of this study was to assess the effectiveness of traditional methods of conservation of silver fir forests. The study analyses the changes in the structure and species composition of a temperate forest excluded from the commercial silvicultural management for 50 years, and since then protected as a nature reserve. The study is based on a comparative analysis of phytosociological reléves made on permanent plots in 1961, 1982, 1994 and 2011. PCA and ecological indicator values were analyzed, as well as characteristic species based on an indicator value (IndVal) index. Results revealed significant and dynamic changes in the forest structure and composition. The mixed coniferous-broadleaved forest with Abies alba and diverse ground flora, considered in the 1960s as valuable and worthy of conservation, was found to have been anthropogenically transformed and unstable. Significant reduction in the human impact was followed by spontaneous regeneration of oak–hornbeam forest. However, the directional process of changes in vegetation was modified by such silvicultural treatments as selective cutting of trees and gap creation, all intended for silver fir maintenance. The results show that Carpinus betulus effectively outcompeted Pinus sylvestris, Picea abies, Quercus robur and A. alba. Changes in the forest overstory and understory caused temporal changes in the habitat conditions reflected in changes in the ground vegetation composition. The proportion of light-demanding and oligotrophic species significantly decreased, while the contribution of species with a wide ecological amplitude, i.e. more shade-tolerant and nutrient-demanding – increased. The share of A. alba was reduced. Species defined in this study as most valuable, should be actively protected, or selection of conservation targets should be re-evaluated

Characterizing forest fragmentation : Distinguishing change in composition from configuration

This project was funded by the Government of Canada through the Mountain Pine Beetle Program, a three-year, $100 million program administered by Natural Resources Canada, Canadian Forest Service. Additional information on the Mountain Pine Beetle Program may be found at: http://mpb.cfs.nrcan.gc.ca.Forest fragmentation can generally be considered as two components: 1) compositional change representing forest loss, and 2) configurational change or change in the arrangement of forest land cover. Forest loss and configurational change occur simultaneously, resulting in difficulties isolating the impacts of each component. Measures of forest fragmentation typically consider forest loss and configurational change together. The ecological responses to forest loss and configurational change are different, thus motivating the creation of measures capable of isolating these separate components. In this research, we develop and demonstrate a measure, the proportion of landscape displacement from configuration (P), to quantify the relative contributions of forest loss and configurational change to forest fragmentation. Landscapes with statistically significant forest loss or configurational change are identified using neutral landscape simulations to generate underlying distributions for P. The new measure, P, is applied to a forest landscape where substantial forest loss has occurred from mountain pine beetle mitigation and salvage harvesting. The percent of forest cover and six LPIs (edge density, number of forest patches, area of largest forest patch, mean perimeter area ratio, corrected mean perimeter area ratio, and aggregation index) are used to quantify forest fragmentation and change. In our study area, significant forest loss occurs more frequently than significant configurational change. The P method we demonstrate is effective at identifying landscapes undergoing significant forest loss, significant configurational change, or experiencing a combination of both loss and configurational change.PostprintPeer reviewe

Insect diversity and composition during the wet and dry seasons in three forest types of Johor, Malaysia

The insect diversity and abundance in three forest types namely: Endau Rompin (pristine lowland forest) Gunung Ledang (pristine highland forest) and Bukit Soga (degraded lowland forest) in Johor, Malaysia were studied. The study focused on 10 common insect orders. The objectives are (1) to investigate the composition and abundance of insect morphospecies in three forest types; (2) to compare the composition and abundance of insect morphospecies in the wet and dry seasons in three forest types; and (3) to determine the dominant insect of the study sites. There were four sampling methods employed as baited pitfall traps, aerial net, manual collection and sweep net. The sampling methods were employed three days in each location. The different insects sampled, were higher during the wet season as compared to the dry season (diversity and abundance). Although Bukit Soga lowland a degraded forest had the highest diversity of 52; and abundance of 112,081 individuals, it had the lowest Shannon weiner index of species diversity and lowest evenness of (H’1.09 and evenness of 0.28). Gunung Ledang, had lowest species diversity of 32 and abundance of 1,695 individuals but had the highest H’of 2.34 and highest evenness of 0.68. Endau Rompin had 46 species diversity and abundance of 70,821individuals and H’of 1.17and evenness of 0.30. In highland forest the most diverse dominant insects were the butterflies (Lepidoptera: Rhopalocera). Meanwhile ant, (Hymenoptera: Formicidae) was more diverse in lowland forest than the highland forest. In all the three locations, ant was most abundant. Since Jaccard similarity index was low between Gunung Ledang and Bukit Soga (0.22); and between Gunung Ledang and Endau Rompin (0.27) it is concluded that altitude had a greater effect on insect diversity. This is supported by a two ways ANOVA analyses that showed insect diversity and abundance between the two lowland forests (Endau Rompin and Bukit Soga) and highland forest (Gunung Ledang) are significantly different. Difference between the lowland forests was not significant. Generally, effect of wet and dry seasons has no clear impact on diversity but abundance was higher during wet season especially for ants (Hymenoptera: Formicidae)