Subalpine meadows in the Dongling Mountains (located at E115o26′-115o40′, N40o00′-40o05′) of Beijing, China are important
for tourism and the provision of ecosystem services. However, because of poor management serious degradation has occurred
on these subalpine meadows. The aim of this paper is to present a quantitative analysis of effects of tourism disturbance
and topography on the status and diversity of montane meadow communities and to provide direction for improved management.
Sixty quadrats of 2 × 2 m2 along 10 transects were set up to collect data on site characteristics and vegetation status. The relationships between community
composition and structure, species diversity, and tourism disturbance and topographic variables were analyzed by multivariate
methods (TWINSPAN and CCA). The results showed that eight meadow communities were identified by TWINSPAN. Most of them were
seriously degraded. The first CCA axis identified an elevation and tourism disturbance intensity gradient, which illustrated
that tourism disturbance and elevation were most important factors influencing meadow types, composition and structure. Some
resistant species and response species to tourism disturbance were identified and can be used as indicator species of tourism
disturbance. Species richness, heterogeneity and evenness were closely related to tourism disturbance and elevation. It is
concluded that tourism disturbance must be controlled to enable grassland rehabilitation to occur in the meadows. Measures
of effective management of the meadows were discussed. 相似文献
The Environmental Protection Agency has encouraged voluntary efforts at pollution prevention by facilities through participation in voluntary environmental programs (VEPs) such as the 33/50 program to reduce toxic releases. This paper examines the effectiveness of the 33/50 program in the adoption of pollution prevention practices and disentangles the effect of adoption from that of program participation on releases of 33/50 chemicals. Using facility-specific panel data and controlling for the endogeneity of program participation and pollution prevention adoption, we find that program participants were 38% more likely to adopt pollution prevention practices than non-participants. Program participants who adopted pollution prevention practices reduced their 33/50 releases by 52% compared to facilities that neither participated nor adopted pollution prevention. This indicates that VEPs that emphasize pollution prevention can play a complementary role in reducing toxic releases. 相似文献
Vibrio bacteria live in both marine and freshwater habitats and are associated with aquatic animals. Vibrio vulnificus is a pathogenic bacterium that infects people and livestock. It is usually found in offshore waters or within fish and shellfish. This study presents a comparative proteomic analysis of the outer membrane protein (OMP) changes in V. vulnificus proteins after stimulation with sewage from sewage drains. Using two-dimensional electrophoresis followed by MALDI-TOF MS/MS, 32 protein spots with significant differences in abundance were identified and characterized. These identified proteins were found to be involved in various functional categories, including catalysis, transport, membrane proteins progresses, receptor activity, energy metabolism, cytokine activity, and protein metabolism. The mRNA expression levels of 12 differential proteins were further assessed by qRT-PCR. Seven genes including carboxypeptidase, hemoglobin receptor, succinate dehydrogenase iron-sulfur subunit, ATP synthase subunit alpha, thioredoxin, succinyl-CoA synthetase subunit, and alanine dehydrogenase were downregulated upon stimulation, whereas the protein expression levels HupA receptor, type I secretion outer membrane protein, glutamine synthetase, superoxide dismutase, OmpU, and VuuA were upregulated. 1H NMR spectra showed 18 dysregulated metabolites from V. vulnificus after the sewage stimulation and the pathogenicity was enhanced after that.