Linking macrodetritivore distribution to desiccation resistance in small forest fragments embedded in agricultural landscapes in Europe

Purpose

Most of the agricultural landscape in Europe, and elsewhere, consists of mosaics with scattered fragments of semi-natural habitat like small forest fragments. Mutual interactions between forest fragments and agricultural areas influence ecosystem processes such as nutrient cycling, a process strongly mediated by the macrodetritivore community, which is however, poorly studied. We investigated macrodetritivore distribution patterns at local and landscape-level and used a key functional trait (desiccation resistance) to gain mechanistic insights of the putative drivers.

Methods

Macrodetritivores were sampled in forest edges-centres of 224 European forest fragments across 14 landscapes opposing in land use intensity. We used a multilevel analysis of variance to assess the relative contribution of different spatial scales in explaining activity-density and Shannon-diversity of woodlice and millipedes, together with a model-based analysis of the multivariate activity-density data testing the effect on species composition. Secondly, we tested if desiccation resistance of macrodetritivores varied across communities at different spatial scales using linear mixed effect models.

Results

Forest edge-centre and landscape use intensity determined activity-density and community composition of macrodetritivores in forest fragments, while fragment characteristics like size and continuity were relatively unimportant. Forest edges and higher intensity landscapes supported higher activity-density of macrodetritivores and determined species composition. Forest edges sustained woodlouse communities dominated by more drought tolerant species.

Conclusions

Landscape use intensity and forest edges are main drivers in macrodetritivore distribution in forest fragments with desiccation resistance a good predictor of macrodetritivore distribution. Key functional traits can help us to predict changes in community structure in changing landscapes.

     

Simultaneous reduction in incidence of Bemisia tabaci (Hemiptera: Aleyrodidae) and Sylepta derogata (Lepidoptera: Pyralidae) using velvetleaf,Abutilon theophrasti as a trap crop

Journal of Pest Science - Trap cropping is a useful tool in sustainable pest management. Trap crops usually target a single species or genus of insect pests. In this study, we assessed the...     

Limitations of soil microbial biomass carbon as an indicator of soil pollution in the field

The size of the soil microbial biomass carbon (SMBC) has been proposed as a sensitive indicator for measuring the adverse effects of contaminants on the soil microbial community. In this study of Australian agricultural systems, we demonstrated that field variability of SMBC measured using the fumigation-extraction procedure limited its use as a robust ecotoxicological endpoint. The SMBC varied up to 4-fold across control samples collected from a single field site, due to small-scale spatial heterogeneity in the soil physicochemical environment. Power analysis revealed that large numbers of replicates (3-93) were required to identify 20% or 50% decreases in the size of the SMBC of contaminated soil samples relative to their uncontaminated control samples at the 0.05% level of statistical significance. We question the value of the routine measurement of SMBC as an ecotoxicological endpoint at the field scale, and suggest more robust and predictive microbiological indicators.     

The use of reclaimed water in electric power stations and other industrial facilities

There has been much recent progress in the use of reclaimed water (treated municipal sewage plant effluent) for use in the cooling circuits of electric utility plants and other industrial facilities. In the greater Los Angeles area, reclaimed water has been used industrially for over 25 years but some major new projects have been initiated in 1995. By using reclaimed water, electric utility generating stations and other industrial facilities can reduce their need for water from higher quality water sources which can then be conserved for other purposes, such as municipal drinking water. This paper presents an overview of the factors required to successfully use reclaimed water as makeup to recirculating cooling systems. The primary focus is on the possible effects on equipment relative to corrosion, deposition and biological fouling and on the required changes in water treatment. Implementation of the use of this water in some new projects began in May 1995. The paper provides some of the latest available results on the use of this water. The pretreatment process for ammonia removal and chlorination practices is also discussed.     

Congenital diffuse hyperplastic goiter associated with perinatal mortality in 11 captive-born bottlenose dolphins (Tursiops truncatus).

Diffuse hyperplastic goiter was diagnosed by histopathology in 11 perinatal bottlenose dolphins (Tursiops truncatus) that died at four separate zoos and aquaria. Thyroid morphology of these animals was compared with the histologically normal thyroids of two stranded wild bottlenose dolphin calves, a neonate and a 2-mo-old calf. Histologic changes included reduced follicular luminal diameter, markedly reduced or absent luminal colloid, hypertrophy of follicular epithelium, and follicular dysplasia. The etiology of the thyroid gland lesion was not identified. Cause of death was not determined for most of these animals, but they were presumed to have died from metabolic derangements associated with the thyroid lesion, drowning, or dystocia.     

Effects of gas-supersaturated water on Rana catesbeiana tadpoles

Rana catesbeiana tadpoles were exposed to gas supersaturated water which resulted in inflation of the gastrointestinal tract with gas. Affected tadpoles floated on the surface, either with their left sides elevated or on their backs. These clinical signs, similar to those of gas bubble disease, could be reversed by reducing the dissolved gas levels. Based on post-exposure observation for 30 days, a 4-day exposure to a ΔP of 160 to 170 mm Hg had no effect on survival. A 10-day exposure increased mortality and the levels of systemic Aeromonas hydrophila bacteria, the etiology of a serious amphibian disease, “Redleg”. Bacterial levels returned to control levels after a 6-day recovery period.     

A scale-sensitive connectivity analysis to identify ecological networks and conservation value in river networks

Existing methods for connectivity analysis still encounter difficulties in explaining functional relationships between network structure and ecological patterns over larger territories or complex structures like dendritic river networks. We propose a method that addresses the problem of scale and resolution in the connectivity analysis of dendritic network structures, illustrated here for the re-colonization of the French Loire river basin by the European otter. The ecological niche factor approach is applied to infer favourable habitat in the river network based on large scale data of land use and hydro-morphology of river segments for the entire river basin. These analyses identified the stressors to the riparian zone of channel straightening, urbanisation and forest fragmentation as the principal factors explaining otter occurrence. Using this estimate of habitat favourability, we used the Integral Index of Connectivity to quantify habitat availability and connectivity in the dendritic river network. When we calculate the integral index of connectivity over different spatial extents by constraining network distances, the scale-sensitivity of the network’s connectivity emerges. Accounting for high mobility by entering larger network distances in the analysis identifies conservation networks and priorities mainly in downstream parts of the river basin, whereas with smaller network distances, more restricted high quality areas in central and upstream parts are highlighted. The presented approach performed better than distribution modelling approaches in explaining species occurrence over the river network and confirms the crucial aspect of connectivity in otter re-colonization.