基于Markov过程的张掖绿洲土地利用预测

根据河西绿洲张掖市2002、2003和2004年3个时点的土地变更详查数据,应用马尔科夫过程模型预测了未来5年内河西绿洲张掖市土地利用结构变化.结果表明: (1) 2006～2010年5年间,河西绿洲张掖市耕地变为园地、林地、牧草地及建设用地.(2) 5年间河西绿洲张掖市土地利用类型面积变化幅度最大的是林地,土地利用类型主要转化表现为由耕地、园地、牧草地、建设用地、未利用土地向林地转化,其中耕地向林地转化的面积最大.     

One size does not fit all: The complex relationship between biodiversity and psychological well-being

Conserving urban biodiversity is often promoted as a ‘win-win’ nature-based solution that can help align public health and biodiversity conservation agendas. Yet, research on the relationship between biodiversity and psychological well-being reveals inconsistent and complex results. This body of research is also restricted to a few socio-cultural and environmental contexts and tends to ignore differences in individual characteristics, such as nature relatedness (i.e., emotional affinity to nature) and ecological knowledge, that can influence people’s experience of biodiversity. The aim of this interdisciplinary research is to explore the relationships between biodiversity and psychological well-being, and test the moderating effect of nature relatedness and ecological knowledge on these relationships. An ecological survey was conducted in 24 small urban gardens in Israel to measure the richness and abundance of birds, butterflies and plants, as well as land cover characteristics. In parallel, a social survey (close-ended questionnaires) was conducted in-situ to measure psychological well-being, nature relatedness, ecological knowledge, perceived species richness and socio-demographic variables. Psychological well-being measures were mostly associated with the cover of woody species, perceived species richness, and to a lesser extent, with actual species richness and abundance, for all taxa. Nature relatedness moderated these relationships. Respondents with high nature relatedness demonstrated positive well-being-richness relationships, while those with intermediate, or low nature relatedness showed no, or even negative relationships, respectively. Opposite relationships were recorded for bird abundance. Overall, individuals demonstrated poor ecological knowledge and this variable moderated only few relations between well-being measures, perceived butterfly richness and bird abundance. Our results demonstrate that one-size-does-not-fit-all when considering the relationship between psychological well-being and biodiversity, and that affinity to nature is a key moderator for this relationship. Designing urban green spaces that provide inclusive and meaningful nature experiences and foster emotional affinity to nature, is therefore key to aligning ecological and social objectives for sustainable urban planning.     

山西晋南地区近56a的气候变化特征、突变与周期分析

利用1954～2009年山西省晋南地区气候观测站平均气温和降水量资料,运用多年趋势线、Mann-Kendall突变检验、滑动t检验和小波分析等方法对晋南地区气候变化特征、突变以及周期特征进行了分析研究。结果表明：近56年来,山西晋南地区的气候有向干暖化转化的趋势。年平均气温上升趋势明显,其变化率为0.28℃/10a,尤...     

黑河中游湿地不同植物群落土壤有机碳分布及影响因素

湿地是全球碳循环重要组成部分之一,具有独特的生态环境效应和功能,对调节全球气候变化具有重要作用。本研究以黑河中游湿地为研究对象,基于实地采样数据、利用植物群落排序和结构方程模型等方法,分析不同植物群落土壤有机碳差异及影响因素。结果表明:湿地不同植物群落间土壤有机碳存在显著差异(P<0.05),土壤有机碳含量在3.56~4.30 g·kg^-1,呈现明显的表聚现象;土壤有机碳主要受容重、pH、土壤全氮、土壤水分、土壤速效氮、土壤盐分、优势物种盖度、总多度、总盖度、非禾本科草本盖度多种因素的影响,表明造成土壤有机碳变化的因素较为复杂;土壤理化性质对土壤有机碳变化的贡献为0.55,植物群落特征对土壤有机碳变化的贡献为0.22,表明在黑河中游造成各植物群落土壤有机碳变化的主要原因是土壤理化性质差异;土壤理化性质对土壤有机碳的影响有两种不同路径,一是土壤理化性质对土壤有机碳的直接影响,二是pH、盐分通过影响总多度从而影响土壤有机碳,表明在土壤有机碳变化的过程中,不仅仅有各影响因素单纯的直接作用,也有影响因素之间的间接作用。该研究结果对干旱区湿地土壤有机碳固存具有一定的参考价值。     

Decision support framework for assessment of non-point-source pollution of groundwater in large irrigation projects

Agriculture is the main non-point polluter of groundwater in irrigated areas as fertilizers and other agrochemicals are the main contaminants in the water that drains out of the root zone to recharge the aquifer. Nitrates from fertilizers, dissolved in percolation losses from rice fields, are the source of pollution considered. The concentration of nitrates in the percolated water depends on the distributed field water and nitrogen balances over the area. Its concentration in the groundwater depends on the total recharge, pollution loading, groundwater flow and solute transport within the aquifer. The development and application of a GIS based decision support framework that integrates field scale models of these processes for assessment of non-point-source pollution of groundwater in canal irrigation project areas is presented. The GIS is used for representing the spatial variations in input data over the area and map the output of the recharge and nitrogen balance models. The latter are used to provide the spatially distributed recharge and pollutant load inputs to the distributed groundwater flow and transport models, respectively. Alternate strategies for water and fertilizer use can be evaluated using this framework to ensure long-term sustainability of productive agriculture in large irrigation projects. The development and application of the framework is illustrated by taking a case study of a large canal irrigation system in India.     

绿洲土地利用/覆盖变化的社会经济与自然驱动力分析——以张掖市甘州区为例

本文以1986年至2004年间8年数据为基础,定量分析了绿洲区土地利用/覆盖变化的社会经济与自然驱动力。文中对各项指标进行了相关分析、主成分分析和回归分析,对社会经济和自然驱动力的11个指标综合分析和对比,确定绿洲区土地利用/覆盖变化的主要驱动因子,阐明干旱区绿洲土地利用/覆盖变化的驱动机制。结果表明:张掖市甘州区土地利用/覆盖变化驱动力的第一主成分、第二主成分的贡献率分别为74.303%和16.960%,反映出绿洲土地利用/覆盖变化驱动力因子的综合性与复杂性,其中,社会经济驱动力在张掖市甘州区LUCC中起到主导作用,自然驱动力相对来说作用较小。     

Vegetation color exposure differences at the community and individual levels: An explanatory framework based on the neighborhood effect averaging problem

Urban green spaces have multiple benefits, yet their distribution is often uneven. Studies on green inequality frequently adopt static exposure assessments, disregarding exposure during individual mobility, resulting in potential biases known as the neighborhood effect bias. Neighborhood effect averaging problem (NEAP) shows that exposure based on personal mobility tends to be average for all participants, compared to exposure based on residence. This study examines the NEAP in the context of green inequality by considering the ornamental value of green space, specifically vegetation color diversity. Considering that vegetation color can attract attention and has health benefits, we hypothesized that it is a key feature related to NEAP, as residents may compensate for poor residential environment by accessing better environmental quality during daily mobility. To investigate this, we compared vegetation color exposure at community and individual levels, assessing whether NEAP exists. Our findings suggest that while communities with high economic levels had significantly higher exposure to vegetation color diversity, the exposure at the individual level tended to be average. Moreover, NEAP appears to be more of an issue when considering vegetation color diversity compared to a measure of total green space such as green view index. We acknowledge that due to the responsiveness of survey, the survey sample includes a higher proportion of the well-educated and employed individuals with potentially higher mobility, which may influence the results. Overall, this study provides supporting evidence for NEAP in the context of vegetation color exposure, but not green view index, emphasizing the critical role of enhancing the ornamental value of green space and strengthening the quality of green space in improving green inequality.     

Management of runoff stored in small tanks for transplanted rice production in the mid-hills of Northwest Himalaya

Scarcity of water in upland areas limits the growing of transplanted rice and the yield of rice grown under rainfed conditions is very low. As the first priority for the use of runoff recycling based water resources is in the dry season followed by the monsoon season, a strategy has been developed to use the surplus water (occurring during the early monsoon season) to grow transplanted rice without compromising the dry season irrigation. Field experiments revealed that under the mid-hill conditions, transplanted rice can be grown as transplanted in 5 cm standing water and thereafter tainted, requiring only 3.0–3.5 cm of water with a yield reduction of about 25% as compared to generally recommended intermittent submergence (2 days after the disappearance of water) requiring 100–130 cm of water. However, the reduction in yield was not significant if 1 week of initial ponding just after transplanting was created. Based on rainfall-runoff analysis, graphs were developed for runoff and volume of water available in water tanks in different durations of early monsoon periods, command-catchment area ratio and the volume of water available after irrigation which is to be used in dry season, as a function of runoff curve numbers. These graphs can be consulted directly to plan irrigation systems for transplanted rice in upland areas.     

A quasi-experimental study on the impact of park accessibility on the mental health of undergraduate students

Public mental health issues have gained growing attention from academics and policymakers due to their increasing prevalence and multiple adverse and severe consequences. Although some studies have supported the benefits of parks on mental health, the causal relationship between park accessibility and mental health remains unclear. By converting a large cross-sectional sample of 22,060 undergraduates nationwide in China into a quasi-panel dataset, this study untangled the causal impact of park accessibility on mental health benefits. We employed a quasi-experimental research design and used a difference-in-difference (DID) model to estimate the causal effects of park accessibility on depression symptoms within varying buffer sizes (i.e., 0.5 km, 1 km, 1.5 km, and 2 km). Furthermore, propensity score matching (PSM) and the Heckman selection model were employed to mitigate the selection bias caused by the prior differences of the treatment group and the control group. The results revealed that park accessibility had a positive effect on mental health and that its influence decreased with increased buffer sizes. Regarding the gender and living-cost differences, park accessibility within the 0.5 km and 1 km buffers had a greater mental health impact on females than on males, and it had a greater impact on high-living cost undergraduates than on low-living cost undergraduates. To increase the mental health benefits of undergraduate students, this study suggests that the provision of parks within a 1 km radius buffer surrounding the campus should be a priority to improve the mental health of undergraduates.