The homogenizing influence of agriculture on forest bird communities at landscape scales

Landscape Ecology - Agricultural expansion is a principal driver of biodiversity loss, but the impacts on community assembly in agro-ecosystems are less clear, especially across regional scales at...     

Using acoustic telemetry and snorkel surveys to study diel activity and seasonal migration of round goby (Neogobius melanostomus) in an estuary of the Western Baltic Sea

In just two decades, round goby Neogobius melanostomus (Pallas) has dispersed throughout most of the Baltic and the North American Great Lakes. It thrives in shallow sheltered areas, where it is impacting native fauna. In Denmark, researchers, governmental institutions and fishers have joined in an effort to establish a sustainable round goby fishery. To do so, basic information about the movement of round goby is essential, so the movements of 50 round gobies were tracked using acoustic telemetry. The results revealed that activity took place mainly at night and seasonal migrations were common. The most frequent migration behaviour observed was a seaward return migration during winter, which was further confirmed by a snorkel survey. Tracking data also revealed riverine upstream dispersal. The results demonstrate that the round goby can be mapped using telemetry, and it is suggested that fishing for round goby may improve efficiency by targeting seasonal migration corridors.     

The potential drivers in forming avian biodiversity hotspots in the East Himalaya Mountains of Southwest China

Little has been published to describe or interpret Asian biodiversity hotspots, including those in the East Himalayan Mountains of Southwest China (HMSC), thus making necessary a review of the current knowledge. The Pliocene and Pleistocene geological and glacial histories of the Asian continent differ from those of Europe and North America, suggesting different mechanisms of speciation and extinction, and, thus, different responses to climate changes during the Quaternary glaciations. This short review summarizes potential drivers in shaping and maintaining high species richness and endemism of birds in the HMSC. The geographical location at the junction of different biogeographical realms, the wide range of habitats and climates along the extensive elevational range, the complex topography and the distinct geological history of this region have probably contributed to the evolution of an exceptionally species‐rich and endemic‐rich, specialized montane avian fauna. The Mountain systems in the HMSC may have provided refugia where species survived during the glacial periods and barriers for preventing species dispersal after the glacial periods. More studies are required to further test this refugia hypothesis by comparing more cold‐tolerent and warm‐tolerent species.     

Mechanical site preparation effects on understory plant diversity in the Piedmont of the southern USA

Diversity of understory vegetation was compared among four intensities of site preparation and an adjacent 50-year-old pine-hardwood forest. The study site was a six-year-old loblolly pine (Pines taeda) plantation in the lower Piedmont of Georgia. Species richness and Shannon diversity indices were used to evaluate vine and woody (trees and shrubs) species diversity. Biomass distribution was compared among four plant categories: vines, forbs, grasses, and woody. Moderate intensity treatments (chainsaw and shear and chop) consistently ranked highest overall in diversity, with the mature pine-hardwood forest ranking lowest. Distribution of the four plant categories was not significantly affected by intensity of site preparation.Alabama Agricultural Experiment Station Series No. 9-892325P.     

Contributions of woody and herbaceous vegetation to tropical savanna ecosystem productivity: a quasi-global estimate

To estimate the relative contributions of woody and herbaceous vegetation to savanna productivity, we measured the 13C/12C isotopic ratios of leaves from trees, shrubs, grasses and the surface soil carbon pool for 22 savannas in Australia, Brazil and Ghana covering the full savanna spectrum ranging from almost pure grassland to closed woodlands on all three continents. All trees and shrubs sampled were of the C3 pathway and all grasses of the C4 pathway with the exception of Echinolaena inflexa (Poir.) Chase, a common C3 grass of the Brazilian cerrado. By comparing the carbon isotopic compositions of the plant and carbon pools, a simple model relating soil delta 13C to the relative abundances of trees + shrubs (woody plants) and grasses was developed. The model suggests that the relative proportions of a savanna ecosystem's total foliar projected cover attributable to grasses versus woody plants is a simple and reliable index of the relative contributions of grasses and woody plants to savanna net productivity. Model calibrations against woody tree canopy cover made it possible to estimate the proportion of savanna productivity in the major regions of the world attributable to trees + shrubs and grasses from ground-based observational maps of savanna woodiness. Overall, it was estimated that 59% of the net primary productivity (Np) of tropical savannas is attributable to C4 grasses, but that this proportion varies significantly within and between regions. The C4 grasses make their greatest relative contribution to savanna Np in the Neotropics, whereas in African regions, a greater proportion of savanna Np is attributable to woody plants. The relative contribution of C4 grasses in Australian savannas is intermediate between those in the Neotropics and Africa. These differences can be broadly ascribed to large scale differences in soil fertility and rainfall.     

Rocky Mountain ecosystems: diversity, complexity and interactions

The interior west of North America provides many opportunities to study ecosystem responses to climate change, biological diversity and management of disturbance regimes. These ecosystem responses are not unique to the Rocky Mountains, but they epitomize similar scientific problems throughout North America. Better management of these ecosystems depends on a thorough understanding of the underlying biology and ecological interactions of the species that occupy the diverse habitats of this region. This review highlights progress in research to understand aspects of this complex ecosystem.     

Ecology of Armillaria species on silver fir (Abies alba) in the Spanish Pyrenees

? We describe the distribution and the ecology of three Armillaria species observed in silver fir (Abies alba) forests of the Pyrenees.

? We surveyed the presence and abundance of Armillaria above and belowground in 29 stands. Isolates were identified by the PCR-RFLP pattern of the IGS-1 region of their ribosomal DNA. We measured several ecological and management parameters of each stand in order to describe Armillaria infected sites.

? Armillaria cepistipes was the most abundant of three species observed. Armillaria gallica was dominant in soils with a higher pH and at lower elevations. Armillaria ostoyae seemed to be more frequent in stands where A. alba recently increased its dominance relative to other forest tree species. Thinning activities correlated with an increased abundance of Armillaria belowground. In 83% of the stands the same Armillaria species was observed above and belowground.

? It seems that in a conifer forest, A. cepistipes can be more frequent than A. ostoyae, a virulent conifer pathogen. Since logging is related to a higher abundance of Armillaria in the soil, the particular Armillaria species present in a given stand could be considered an additional site factor when making management decisions.