Impact of litter quality and soil nutrient availability on leaf decomposition rate in a semi-arid grassland of Northeast China   总被引：4，自引：0，他引：4  

Lu-Jun Li  De-Hui Zeng  Zhan-Yuan YuZhi-Ping Fan  Dan YangYun-Xia Liu 《Journal of Arid Environments》2011,75(9):787-792

It was hypothesized that litter with higher N concentration would decompose faster than that with lower N concentration and that increased soil nutrient availability would stimulate litter decomposition. To examine the interspecific differences in decomposition rate of leaf litter in relation with differences in litter chemistry and soil nutrient availability, senescent leaves of four species Pennisetum flaccidum, Artemisia scoparia, Chenopodium acuminatum and Cannabis sativa, and soil samples with different fertilization treatments (no fertilization, N, P, and N + P fertilizations, respectively) were collected from a sandy grassland in Northeast China and incubated under laboratory conditions. The decomposition rate of leaf litter was determined by measuring the CO₂ emission during decomposition of litter. We found remarkable interspecific differences in leaf decomposition rates. Moreover, rates of litter decomposition at different incubation stages were correlated with different litter quality indices. The rate of litter decomposition was positively correlated with initial litter N concentration in the initial stage of the incubation, whereas it was negatively correlated with litter N and P concentrations in the late stage. Responses of litter decomposition to soil nutrient availability differed among species. Our results suggest that both indirect changes in litter quality through shifts of species composition/dominance and direct changes in soil nutrient availability under nutrient addition conditions could affect litter decomposition and consequently C and nutrient cycling of grassland ecosystems.  相似文献   

Comparing biodiversity between protected savanna and adjacent non-protected farmland in the southern Kalahari     

Bernd Wasiolka  Niels Blaum 《Journal of Arid Environments》2011,75(9):836-841

In this study we investigated the effect of different land use options (wildlife versus livestock) on species richness of plants and reptiles in the protected Kgalagadi Transfrontier Park (KTP) versus adjacent non-protected farmland within the same savanna habitat type (Aoub dune veld) in the southern Kalahari, South Africa. Our results show that both plant and reptile species richness as well as plant cover and reptile abundance was significantly higher in the protected KTP than in the non-protected farmland. The higher proportion of shrub but lower proportions of perennial grass cover, herb cover, and herb species richness in the farmland can be explained by higher stocking rates and the differences in feeding behaviour between native wild ungulates (e.g. Antidorcas marsupialis, Oryx gazella) and livestock (mainly sheep). The reptile’s prey availability and microhabitats (perennial grass tussocks and rodent burrows) for thermoregulation and protection against predators were significantly lower in the farmland. To conclude, our results clearly show that long term effects of different land use options (wildlife in protected KTP versus extensive livestock production in the non-protected farmland) even within the same habitat type have led to significant changes in vegetation composition, availability of microhabitat structures and in the reptile community.  相似文献   

Spatial patterns of the soil seed bank and extant vegetation across the dry Minjiang River valley in southwest China     

Y.J. Li  W.K. Bao  N. Wu 《Journal of Arid Environments》2011,75(11):1083-1089

The medium-scale spatial patterns of soil seed banks (SSBs) and extant vegetation and the roles of abiotic factors are poorly understood. We selected the dry Minjiang River valley of southwest China to investigate SSB structure and corresponding extant vegetation in a medium-scale size (200-230 km long, 3-4 km wide) at eight sites across the valley using a germination method and field surveys. We found that, there was low seed density and species number in SSB and less coverage and litter thickness for community in extant vegetation at central sites compared with transitional sites across the dry valley; Quercus spp. occurred frequently in extant vegetation at transitional sites, while Caryopteris spp., Jasminum spp., Rabdosia parvifolia, Sophora davidii, Campylotropis spp., and Bauhinia faberi var. Microphylla was present frequently at central sites; Carex spp. and Artemisia spp. occurred frequently in SSB at transitional sites, while Ajania spp., Poa spp., and Fagopyrum caudatum was present more frequently at central sites. Hierarchical cluster analysis and Kendall’s correlation showed that the spatial variation of both SSB and extant vegetation had significant correlation with rainfall and air evaporation.  相似文献   

Living on the edge? - On the thermobiology and activity pattern of the large herbivorous desert lizard Uromastyx aegyptia microlepis Blanford, 1875 at Mahazat as-Sayd Protected Area, Saudi Arabia     

T.M. Wilms  P. WagnerM. Shobrak  D. RödderW. Böhme 《Journal of Arid Environments》2011,75(7):636-647

Field active body temperatures (T_b) and operative temperatures (T_e) were assessed in a population of Uromastyx aegyptia microlepis at Mahazat as-Sayd Protected Area, Saudi Arabia. In summer T_b ranged between 23.2 and 47.2 °C, in winter between 23.0 and 45.1 °C and in spring between 25.5 and 45.9 °C. There is a significant difference between respective T_b and T_e distributions which suggests that U. a. microlepis is an active thermoregulator. Above ground activity is very variable between seasons, with the highest activity level in spring. In winter the animals showed an unimodal activity profile. In spring and summer the lizards exhibit bimodal activity profiles with afternoon activity being generally lower than morning activity levels. Species distribution models were calculated to estimate the future impact of global warming on this taxon. Estimates on the basis of temperature data suggest that the range size on the Arabian Peninsula might be stable but with a remarkable decrease of environmental suitability of up to 70-80%. Based on a synthesis of thermo-ecological data and species distribution models we consider climate warming as a potential threat to the survival of the species.  相似文献   

Fire and ecosystem heterogeneity: A mediterranean case study     

Pua Kutiel 《地球表面变化过程与地形》1994,19(2):187-194

The response of a Mediterranean ecosystem to fire is summarized in this paper. The results were obtained over a 3-year period at sites with a known fire history on Mt Carmel, Israel. The results give some idea of the complexity and variability of the ecosystem response to fire, and about factors that could determine these responses. It also shows how fire increases species and landscape diversity.  相似文献   

Assessing regional differences in predation of endangered species: Implications from Texas populations of the endangered star cactus (Astrophytum asterias)     

《Journal of Arid Environments》2013

Understanding threats to endangered species is one of the most critical components of implementing a successful recovery plan. For the endangered star cactus Astrophytum asterias, both mammalian and insect herbivory have been documented as a major threat to populations in Mexico. Herein, we focus on populations of A. asterias in Texas, examining how mortality threats differ from populations found in Mexico as well as among sites within Texas. Our study supports insect and mammalian herbivory as a major threat to A. asterias in Texas, with reductions in population sizes ranging between 16 and 54%. However, our study highlights that both regional and local differences can influence rates of mortality even in a range-restricted species such as A. asterias and highlights the need to assess threats at both of these levels for effective development and implementation of endangered species recovery plans.  相似文献   

The effects of enclosures and land-use contracts on rangeland degradation on the Qinghai–Tibetan plateau     

《Journal of Arid Environments》2013

Rangeland degradation on the Qinghai–Tibetan Plateau is a growing concern, often attributed to climate change and overgrazing. A minority of researchers have suggested instead that degradation may be caused by changes in land management, particularly enclosures and the contracting of long-term rangeland use rights to households. However, these claims have been hampered by a lack of empirical evidence. This field experiment is the first to compare rangeland conditions over time in the case of different management regimes on the Qinghai–Tibetan Plateau, specifically single-household versus multi-household management. A survey of vegetation properties in Maqu County, Gansu province in 2009, and repeated in 2011, examined the differences between single- and multi-household management in terms of vegetation biomass, cover, and species richness. In 2009, the biomass of the sedge group under multi-household management was significantly higher than that under single-household management. In 2011, biomass, vegetation cover, and species richness were all significantly higher under multi-household management than single-household management. These data suggest the flaws of the tragedy of the commons assumptions underlying single-household management.  相似文献   

Adaptive management,international co-operation and planning for marine conservation hotspots in a changing climate     

《Marine Policy》2015

The aim of this study is to predict changes in the distribution and extent of habitat forming species defined as “Priority Marine Habitats” (PMHs) in the North-East (NE) Atlantic under future scenarios of climate-induced environmental change. A Species Distribution Modelling method was used for each PMH to map the potential distribution of “most suitable” habitat. The area and percentage cover was calculated within each country׳s Exclusive Economic Zone for the baseline (2009) and the projected (2100) years. In addition, a conservation management score was calculated based on the number of PMHs that co-occur in assessment units. Overall, this study reveals the potential for movement and/or change in the extent of some PMHs across the NE Atlantic under an increased ocean temperature scenario (4 °C) by 2100. There are regional differences in the predicted changes and some countries will experience greater/different changes than others. The movement of biodiversity hotspots (where one or more PMHs occur in the same broad area) provides both opportunities and risks for conservation management that are discussed. Co-operation between neighbouring countries and marine regions will require substantial enhancement in order to provide a robust adaptive management strategy going forward.  相似文献   

Habitat suitability and protection status of four species of amphibians in the Dominican Republic     

《Applied geography (Sevenoaks, England)》2015

Hispaniola Island has both a high level of amphibian endemism, and a high level of habitat degradation due to agriculture, infrastructure development, and extractive industries. The objective of this work was to evaluate the capacity of Dominican Republic's current network of protection to maintain the habitat of four species of amphibians endemic to Hispaniola (Osteopilus pulchrilineatus, Osteopilus vastus, Hypsiboas heilprini, and Eleutherodactylus flavescens). Spatial analysis was performed to relate observations of the target species to environmental factors using a maximum entropy algorithm (Maxent). Results of this analysis produced maps of probability of occurrence for each species. Analysis of habitat degradation was based on a change analysis of vegetation, by evaluating trends in the normalized difference vegetation index (NDVI) between 2000 and 2011. Results show that forest loss and species habitat loss within protected areas are smaller but similar to those extracted for the country as a whole, suggesting that the current protected area network is not effective for the maintenance of the habitat of the amphibians analyzed. Enforcement of established protection and restoration within current protected areas could facilitate the protection of up to 25.7% of target amphibian habitat. The methodologies presented here can be applied to measure biodiversity offset effectiveness.  相似文献   

Mapping the stray domestic cat (Felis catus) population in New Zealand: Species distribution modelling with a climate change scenario and implications for protected areas     

《Applied geography (Sevenoaks, England)》2015

Species distribution models of stray cats were developed using two types of occurrence data: (i) a combined dataset of stray cats and cat colonies in Auckland and projected to the wider New Zealand area; and (ii) population density as an analogue for country-wide stray cat occurrence. These occurrence data, together with sets of environmental variables were used as input to the Maxent modelling tool to produce maps of suitability for the species. Environmental variables used in the models consist of current bioclimatic conditions, and a future climate scenario (RCP8.5 for year 2070 CCSM model). Commonly occurring bias in the modelling process due to latitude, the area for selecting background points in model evaluation, inherent spatial autocorrelation of occurrence points, and correlated bioclimatic variables were explicitly addressed. Results show that the North Island consistently provide more suitable areas for stray cats with increased suitability in a high emission climate change condition. Key protected areas at risk from the increased suitability to stray cats are also presented.  相似文献