Does habitat loss affect the communities of plants and insects equally in plant–pollinator interactions? Preliminary findings

Habitat loss is a major threat to biodiversity and ecosystem function. As habitats are lost, one factor affecting their community structures is the niche-width demand of species, which ranges from specialist to generalist. This study focused on specialist and generalist species in plant–pollinator interactions and tested the hypothesis that plant and pollinator communities become more generalized as habitat loss increases. The study was made in seven selected sites in southern Ontario, Canada, at the level of landscape that is characterized by distributed forests within intensively managed agricultural fields. We quantified both the degree of habitat loss and the degree of specialization/generalization for each of the plant and insect communities using a sampling method of hexagonal transects. Regression analysis indicated a significant relationship between the increase of habitat loss and the shift to generalization in insect, but not in plant, communities. Our results suggest that, in plant–pollinator interactions, insect communities are more sensitive and/or quicker than plant communities to respond to the effects of habitat loss.     

Estimating species – area relationships by modeling abundance and frequency subject to incomplete sampling

Models and data used to describe species–area relationships confound sampling with ecological process as they fail to acknowledge that estimates of species richness arise due to sampling. This compromises our ability to make ecological inferences from and about species–area relationships. We develop and illustrate hierarchical community models of abundance and frequency to estimate species richness. The models we propose separate sampling from ecological processes by explicitly accounting for the fact that sampled patches are seldom completely covered by sampling plots and that individuals present in the sampling plots are imperfectly detected. We propose a multispecies abundance model in which community assembly is treated as the summation of an ensemble of species‐level Poisson processes and estimate patch‐level species richness as a derived parameter. We use sampling process models appropriate for specific survey methods. We propose a multispecies frequency model that treats the number of plots in which a species occurs as a binomial process. We illustrate these models using data collected in surveys of early‐successional bird species and plants in young forest plantation patches. Results indicate that only mature forest plant species deviated from the constant density hypothesis, but the null model suggested that the deviations were too small to alter the form of species–area relationships. Nevertheless, results from simulations clearly show that the aggregate pattern of individual species density–area relationships and occurrence probability–area relationships can alter the form of species–area relationships. The plant community model estimated that only half of the species present in the regional species pool were encountered during the survey. The modeling framework we propose explicitly accounts for sampling processes so that ecological processes can be examined free of sampling artefacts. Our modeling approach is extensible and could be applied to a variety of study designs and allows the inclusion of additional environmental covariates.     

Forest biodiversity,ecosystem functioning and the provision of ecosystem services

Forests are critical habitats for biodiversity and they are also essential for the provision of a wide range of ecosystem services that are important to human well-being. There is increasing evidence that biodiversity contributes to forest ecosystem functioning and the provision of ecosystem services. Here we provide a review of forest ecosystem services including biomass production, habitat provisioning services, pollination, seed dispersal, resistance to wind storms, fire regulation and mitigation, pest regulation of native and invading insects, carbon sequestration, and cultural ecosystem services, in relation to forest type, structure and diversity. We also consider relationships between forest biodiversity and multifunctionality, and trade-offs among ecosystem services. We compare the concepts of ecosystem processes, functions and services to clarify their definitions. Our review of published studies indicates a lack of empirical studies that establish quantitative and causal relationships between forest biodiversity and many important ecosystem services. The literature is highly skewed; studies on provisioning of nutrition and energy, and on cultural services, delivered by mixed-species forests are under-represented. Planted forests offer ample opportunity for optimising their composition and diversity because replanting after harvesting is a recurring process. Planting mixed-species forests should be given more consideration as they are likely to provide a wider range of ecosystem services within the forest and for adjacent land uses. This review also serves as the introduction to this special issue of Biodiversity and Conservation on various aspects of forest biodiversity and ecosystem services.     

The PTH/PTHrP receptor can delay chondrocyte hypertrophy in vivo without activating phospholipase C

One G protein-coupled receptor (GPCR) can activate more than one G protein, but the physiologic importance of such activation has not been demonstrated in vivo. We have generated mice expressing exclusively a mutant form of the PTH/PTHrP receptor (DSEL) that activates adenylyl cyclase normally but not phospholipase C (PLC). DSEL mutant mice exhibit abnormalities in embryonic endochondral bone development, including delayed ossification and increased chondrocyte proliferation. Analysis of the differentiation of embryonic metatarsals in vitro shows that PTH(1-34) and forskolin inhibit, whereas active phorbol ester stimulates, hypertrophic differentiation. Thus, PLC signaling via the PTH/PTHrP receptor normally slows the proliferation and hastens the differentiation of chondrocytes, actions that oppose the dominant effects of PTH/PTHrP receptors and that involve cAMP-dependent signaling pathways.     

High-rate thermophilic methane fermentation on short-chain fatty acids in a down-flow anaerobic packed-bed reactor

In order to maximize the efficiency of methane fermentation on short-chain fatty acids, growth media containing acetic acid and butyric acid as major carbon sources were supplied to a thermophilic down-flow anaerobic packed-bed reactor. The organic loading rate (OLR) to the reactor ranged from 0.2 to 169 kg-dichromate chemical oxygen demand(CODcr)/m³-reactor/day, corresponding to a hydraulic retention time (HRT) of between 1.4 h and 20 days. Stable methane production was maintained at HRTs as short as 2 h (OLR=120 kg-CODcr/m³/day), with the short-chain fatty acids in the feed almost completely removed during the process. The apparent substrate removal efficiency, determined from the total CODcr values in the influent and effluent, was 75% at short HRTs. However, the actual substrate removal efficiency must have been greater than 75%, since a fraction of substrate was also utilized in microbial cell synthesis, and these cells were part of the measured total CODcr.     

Spatial and temporal influences of conifer planted forests on the orchard pest Plautia stali (Hemiptera: Pentatomidae)

Land use changes have generally been considered a local matter, but they are becoming an issue of much wider concern as changes in the use of non-agricultural lands occasionally generate nationwide agricultural pest problems. Plautia stali Scott is a serious pest in orchards, and the widespread distribution of this pest is likely associated with the expansion of planted coniferous forests in Japan. An experiment was conducted on 29 study sites in diverse areas of planted coniferous forest in central Japan, and the abundance of P. stali was monitored over four seasons for 3 years. Results revealed that the optimum radius required to cause an effect on the area surrounding the conifer planted forest was up to 4 km—specifically, 2,000, 400, 1,500, and 200 m in April, June, August, and October, respectively. Positive correlations were observed between conifer planted forests and the collected numbers of P. stali in April, June, and August. These temporal scales provide a direct evaluation of the landscape effects of a conifer planted forest on population dynamics, and this information will contribute to the development and improvement of area-wide P. stali management.