Temporal patterns of land-use change and carbon storage in China and tropical Asia

Evaluating the annual sources and sinks of carbon from land-use changehelps constrain other terms in the global carbon cycle and may help countries choose how to comply with commitments for reduced emissions. This paper presents the results of recent analyses of land-use change in China and tropical Asia. The original forest areas are estimated to have covered 546×106 ha in tropical Asia and 425×106 ha in China. By 1850, 44% of China's forests had been cleared, and another 27% was lost between 1850 and 1980, leaving China with 13% forest cover (29% of the initial forest area). Tropical Asia is estimated to have lost 26%of its initial forest cover before 1850 and another 33% after 1850. The annual emissions of carbon from the two regions reflect the different histories over the last 150 years, with China's emissions peaking in the late 1950s (at 0.2-0.5 Pg C@a-1) and tropical Asia's emissions peaking in 1990s (at 1.0 Pg C@a-1). Despite the fact that most deforestation has been for new agricultural land, the majority of the lands cleared from forests in China are no longer croplands, but fallow or degraded shrublands. Unlike croplands, the origins of these other lands are poorly documented, and thus add considerable uncertainty to estimates of flux before the 1980s. Nevertheless, carbon emissions from China seem to have decreased since the 1960s to nearly zero at present. In contrast, emissions of carbon from tropical Asia were higher in the 1990s than that at any time in the past.     

Temporal patterns of land-use change and carbon storage in China and tropical Asia

Evaluating the annual sources and sinks of carbon from land-use change helps con-strain other terms in the global carbon cycle and may help countries choose how to comply with commitments for reduced emissions. This paper presents the results of recent analyses ofland-use change in China and tropical Asia. The original forest areas are estimated to have cov-ered 546×10~6 ha in tropical Asia and 425×10~6 ha in China. By 1850, 44% of China's forests had been cleared, and another 27% was lost between 1850 and 1980, leaving China with 13% forestcover (29% of the initial forest area). Tropical Asia is estimated to have lost 26% of its initial forestcover before 1850 and another 33% after 1850. The annual emissions of carbon from the two regions re-flect the different histories over the last 150 years, with China's emissions peaking in thelate 1950s (at 0.2-0.5 Pg C·a~(-1)) and tropical Asia's emissions peaking in 1990s (at 1.0 Pg C·a~(-1)). Despite the fact that most deforestation has been for new agricultural land, the majority ofthe lands cleared from forests in China are no longer croplands, but fallow or degraded shrublands.Unlike croplands, the origins of these other lands are poorly documented, and thus add consider-able uncertainty to estimates of flux before the 1980s. Nevertheless, carbon emissions from China seem to have decreased since the 1960s to nearly zero at present. In contrast, emissions of car-bon from tropical Asia were higher in the 1990s than that at any time in the past.     

Tracing the future of epidemics: Coincident niche distribution of host animals and disease incidence revealed climate-correlated risk shifts of main zoonotic diseases in China

Climate has critical roles in the origin, pathogenesis and transmission of infectious zoonotic diseases. However, large-scale epidemiologic trend and specific response pattern of zoonotic diseases under future climate scenarios are poorly understood. Here, we projected the distribution shifts of transmission risks of main zoonotic diseases under climate change in China. First, we shaped the global habitat distribution of main host animals for three representative zoonotic diseases (2, 6, and 12 hosts for dengue, hemorrhagic fever, and plague, respectively) with 253,049 occurrence records using maximum entropy (Maxent) modeling. Meanwhile, we predicted the risk distribution of the above three diseases with 197,098 disease incidence records from 2004 to 2017 in China using an integrated Maxent modeling approach. The comparative analysis showed that there exist highly coincident niche distributions between habitat distribution of hosts and risk distribution of diseases, indicating that the integrated Maxent modeling is accurate and effective for predicting the potential risk of zoonotic diseases. On this basis, we further projected the current and future transmission risks of 11 main zoonotic diseases under four representative concentration pathways (RCPs) (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) in 2050 and 2070 in China using the above integrated Maxent modeling with 1,001,416 disease incidence records. We found that Central China, Southeast China, and South China are concentrated regions with high transmission risks for main zoonotic diseases. More specifically, zoonotic diseases had diverse shift patterns of transmission risks including increase, decrease, and unstable. Further correlation analysis indicated that these patterns of shifts were highly correlated with global warming and precipitation increase. Our results revealed how specific zoonotic diseases respond in a changing climate, thereby calling for effective administration and prevention strategies. Furthermore, these results will shed light on guiding future epidemiologic prediction of emerging infectious diseases under global climate change.     

Emissions of carbon from forestry and land-use change in tropical Asia

The net emissions of carbon from forestry and changes in land use in south and southeast Asia were calculated here with a book-keeping model that used rates of land-use change and associated per hectare changes in vegetation and soil to calculate changes in the amount of carbon held in terrestrial ecosystems and wood products. The total release of carbon to the atmosphere over the period 1850–1995 was 43.5 PgC. The clearing of forests for permanent croplands released 33.5 PgC, about 75% of the total. The reduction of biomass in the remaining forests, as a result of shifting cultivation, logging, fuelwood extraction, and associated regrowth, was responsible for a net loss of 11.5 PgC, and the establishment of plantations withdrew from the atmosphere 1.5 PgC, most of it since 1980. Based on comparisons with other estimates, the uncertainty of this long-term flux is estimated to be within ±30%. Reducing this uncertainty will be difficult because of the difficulty of documenting the biomass of forests in existence >40 years ago. For the 15-y period 1981–1995, annual emissions averaged 1.07 PgC y^–1, about 50% higher than reported for the 1980s in an earlier study. The uncertainty of recent emissions is probably within ± 50% but could be reduced significantly with systematic use of satellite data on changes in forest area. In tropical Asia, the emissions of carbon from land-use change in the 1980s accounted for approximately 75% of the region’s total carbon emissions. Since 1990 rates of deforestation and their associated emissions have declined, while emissions of carbon from combustion of fossil fuels have increased. The net effect has been a reduction in emissions of CO₂ from this region since 1990.     

Seasonality in human zoonotic enteric diseases: a systematic review

Background

Although seasonality is a defining characteristic of many infectious diseases, few studies have described and compared seasonal patterns across diseases globally, impeding our understanding of putative mechanisms. Here, we review seasonal patterns across five enteric zoonotic diseases: campylobacteriosis, salmonellosis, vero-cytotoxigenic Escherichia coli (VTEC), cryptosporidiosis and giardiasis in the context of two primary drivers of seasonality: (i) environmental effects on pathogen occurrence and pathogen-host associations and (ii) population characteristics/behaviour.

Methodology/Principal Findings

We systematically reviewed published literature from 1960–2010, resulting in the review of 86 studies across the five diseases. The Gini coefficient compared temporal variations in incidence across diseases and the monthly seasonality index characterised timing of seasonal peaks. Consistent seasonal patterns across transnational boundaries, albeit with regional variations was observed. The bacterial diseases all had a distinct summer peak, with identical Gini values for campylobacteriosis and salmonellosis (0.22) and a higher index for VTEC (Gini = 0.36). Cryptosporidiosis displayed a bi-modal peak with spring and summer highs and the most marked temporal variation (Gini = 0.39). Giardiasis showed a relatively small summer increase and was the least variable (Gini = 0.18).

Conclusions/Significance

Seasonal variation in enteric zoonotic diseases is ubiquitous, with regional variations highlighting complex environment-pathogen-host interactions. Results suggest that proximal environmental influences and host population dynamics, together with distal, longer-term climatic variability could have important direct and indirect consequences for future enteric disease risk. Additional understanding of the concerted influence of these factors on disease patterns may improve assessment and prediction of enteric disease burden in temperate, developed countries.     

Increasing synergistic effects of habitat destruction and hunting on mammals over three decades in the Gran Chaco

Habitat destruction and overexploitation are the main threats to biodiversity and where they co-occur, their combined impact is often larger than their individual one. Yet, detailed knowledge of the spatial footprints of these threats is lacking, including where they overlap and how they change over time. These knowledge gaps are real barriers for effective conservation planning. Here, we develop a novel approach to reconstruct the individual and combined footprints of both threats over time. We combine satellite-based land-cover change maps, habitat suitability models and hunting pressure models to demonstrate our approach for the community of larger mammals (48 species > 1 kg) across the 1.1 million km² Gran Chaco region, a global deforestation hotspot covering parts of Argentina, Bolivia and Paraguay. This provides three key insights. First, we find that the footprints of habitat destruction and hunting pressure expanded considerably between 1985 and 2015, across ~40% of the entire Chaco – twice the area affected by deforestation. Second, both threats increasingly acted together within the ranges of larger mammals in the Chaco (17% increase on average, ± 20% SD, cumulative increase of co-occurring threats across 465 000 km²), suggesting large synergistic effects. Conversely, core areas of high-quality habitats declined on average by 38%. Third, we identified remaining priority areas for conservation in the northern and central Chaco, many of which are outside the protected area network. We also identify hotspots of high threat impacts in central Paraguay and northern Argentina, providing a spatial template for threat-specific conservation action. Overall, our findings suggest increasing synergistic effects between habitat destruction and hunting pressure in the Chaco, a situation likely common in many tropical deforestation frontiers. Our work highlights how threats can be traced in space and time to understand their individual and combined impact, even in situations where data are sparse.     

Vulnerability of African mammals to anthropogenic climate change under conservative land transformation assumptions

Recent observations show that human‐induced climate change (CC) and land transformation (LT) are threatening wildlife globally. Thus, there is a need to assess the sensitivity of wildlife on large spatial scales and evaluate whether national parks (NPs), a key conservation tools used to protect species, will meet their mandate under future CC and LT conditions. Here, we assess the sensitivity of 277 mammals at African scale to CC at 10′ resolution, using static LT assumptions in a ‘first‐cut’ estimate, in the absence of credible future LT trends. We examine the relationship between species' current distribution and macroclimatic variables using generalized additive models, and include LT indirectly as a filter. Future projections are derived using two CC scenarios (for 2050 and 2080) to estimate the spatial patterns of loss and gain in species richness that might ultimately result. We then apply the IUCN Red List criteria A3(c) of potential range loss to evaluate species sensitivity. We finally estimate the sensitivity of 141 NPs in terms of both species richness and turnover. Assuming no spread of species, 10–15% of the species are projected to fall within the critically endangered or extinct categories by 2050 and between 25% and 40% by 2080. Assuming unlimited species spread, less extreme results show proportions dropping to approximately 10–20% by 2080. Spatial patterns of richness loss and gain show contrasting latitudinal patterns with a westward range shift of species around the species‐rich equatorial zone in central Africa, and an eastward shift in southern Africa, mainly because of latitudinal aridity gradients across these ecological transition zones. Xeric shrubland NPs may face significant richness losses not compensated by species influxes. Other NPs might expect substantial losses and influxes of species. On balance, the NPs might ultimately realize a substantial shift in the mammalian species composition of a magnitude unprecedented in recent geological time. To conclude, the effects of global CC and LT on wildlife communities may be most noticeable not as a loss of species from their current ranges, but instead as a fundamental change in community composition.     

人为热排放对城市热环境的影响研究展望

全球范围的城市扩张和能源消耗,导致人为热在不同时间和空间尺度上影响地表热环境,人为热排放与城市热岛的关系受到广泛关注。通过国内外文献总结源清单法、数值模拟法和能量平衡方程等3种人为热估算方法的优缺点,评价人为热研究在城市、区域和全球尺度的主要进展和区别,归纳出现有研究在城市尺度多关注人为热的时间动态变化,区域和全球尺度研究则更关注人为热的空间差异,以及人为热对于全球变暖的贡献和人类的适应对策。从中发现人为热研究中存在的问题和不足,包括研究尺度和研究方法匹配性、研究结果的验证和比较、人为热排放与景观功能的联系、人为热排放强度和周期对气温的影响机制等。根据现存问题提出多学科集成、人为热与景观功能耦合、时空尺度选择、数据获取等4个方面的建议,有助于在理论和方法方面深化和拓展城市人为热研究。     

Ecological effects of non‐native species in marine ecosystems relate to co‐occurring anthropogenic pressures

Predictors for the ecological effects of non‐native species are lacking, even though such knowledge is fundamental to manage non‐native species and mitigate their impacts. Current theories suggest that the ecological effects of non‐native species may be related to other concomitant anthropogenic stressors, but this has not been tested at a global scale. We combine an exhaustive meta‐analysis of the ecological effects of marine non‐native species with human footprint proxies to determine whether the ecological changes due to non‐native species are modulated by co‐occurring anthropogenic impacts. We found that non‐native species had greater negative effects on native biodiversity where human population was high and caused reductions in individual performance where cumulative human impacts were large. On this basis we identified several marine ecoregions where non‐native species may have the greatest ecological effects, including areas in the Mediterranean Sea and along the northwest coast of the United States. In conclusion, our global assessment suggests coexisting anthropogenic impacts can intensify the ecological effects of non‐native species.     

Facultative mutualisms: A double‐edged sword for foundation species in the face of anthropogenic global change

Ecosystems worldwide depend on habitat‐forming foundation species that often facilitate themselves with increasing density and patch size, while also engaging in facultative mutualisms. Anthropogenic global change (e.g., climate change, eutrophication, overharvest, land‐use change), however, is causing rapid declines of foundation species‐structured ecosystems, often typified by sudden collapse. Although disruption of obligate mutualisms involving foundation species is known to precipitate collapse (e.g., coral bleaching), how facultative mutualisms (i.e., context‐dependent, nonbinding reciprocal interactions) affect ecosystem resilience is uncertain. Here, we synthesize recent advancements and combine these with model analyses supported by real‐world examples, to propose that facultative mutualisms may pose a double‐edged sword for foundation species. We suggest that by amplifying self‐facilitative feedbacks by foundation species, facultative mutualisms can increase foundation species’ resistance to stress from anthropogenic impact. Simultaneously, however, mutualism dependency can generate or exacerbate bistability, implying a potential for sudden collapse when the mutualism's buffering capacity is exceeded, while recovery requires conditions to improve beyond the initial collapse point (hysteresis). Thus, our work emphasizes the importance of acknowledging facultative mutualisms for conservation and restoration of foundation species‐structured ecosystems, but highlights the potential risk of relying on mutualisms in the face of global change. We argue that significant caveats remain regarding the determination of these feedbacks, and suggest empirical manipulation across stress gradients as a way forward to identify related nonlinear responses.     

Beyond Disciplinary Boundaries: Leptospirosis as a Model of Incorporating Transdisciplinary Approaches to Understand Infectious Disease Emergence

Leptospirosis is a zoonotic infectious disease of global significance. Political, economic, demographic, ecologic, and other anthropogenically driven environmental changes have fueled the reemergence of this disease in industrialized and developing countries, and in both urban and rural settings. We argue that conventional disciplinary, even interdisciplinary, research methods are not sufficient to elucidate the complex mechanisms and causal relationships among the myriad factors responsible for infectious disease emergence. To address the significant gaps in the field of leptospirosis, an integrated research agenda is needed to guide successful public health remediation of the disease. Based on both working group analysis of literature and newly obtained information, we describe cross-disciplinary collaborative approaches that allow a novel approach to understand leptospirosis emergence with regard to mountain-to-sea ecosystems in Hawai‘i and other region-specific ecosystems. Leptospirosis research is a model for how complementary disciplines in the social, cultural, ecological, and biomedical sciences can optimally interact towards a higher understanding of emerging infectious diseases.     

A systematic review of adaptive wildlife management for the control of invasive,non-native mammals,and other human–wildlife conflicts

1. We are entering an era where species declines are occurring at their fastest ever rate, and the increased spread of non-native species is among the top causes. High uncertainty in biological processes makes the accurate prediction of the outcomes of management interventions very challenging. Adaptive management (AM) offers solutions to reduce uncertainty and improve predictability so that the outcomes of interventions can continuously improve.
2. We quantitatively assess the extent to which AM is used for managing vertebrates, with a focus on invasive non-native species (INNS). Using the Web of Science, we evaluated 3992 articles returned by the search terms ‘adaptive management’ or ‘adaptive harvest management’ against seven recommended elements of AM (engagement with stakeholders, defining objectives, forecasting and estimating uncertainty, implementing management, monitoring populations, adjusting management in response to monitoring, and improving forecasting and reducing uncertainty in response to monitoring populations).
3. The use of AM for vertebrates was reported in 56 (1%) of the evaluated studies; including four for managing INNS. Of these, ten studies excluding INNS and no studies of INNS management implemented all seven recommended elements of AM. Those elements infrequently implemented were as follows: the use of analysis or models to forecast and represent uncertainty (44%) and the feedback of monitoring data to improve forecasting and reduce uncertainty (25%).
4. Complete active AM has rarely been implemented and reported for managing INNS, despite the significant advantages it offers. Among studies purporting to have implemented AM, most did not use analyses or models to forecast and represent uncertainty, while most defined objectives, implemented management, and monitored populations.
5. Improvements to ongoing control programmes and much broader adoption of the AM approach are required to increase the efficiency and success of INNS management campaigns and reduce their negative impacts on native species.

     

流域土地利用变化对不同重现期洪水的影响——以奉化江皎口水库流域为例

土地利用变化对流域洪水过程产生显著影响,并导致设计洪水发生变化。为进一步指导流域防洪及水库洪水设计,以浙东沿海奉化江皎口水库流域为例,应用HEC-HMS水文模型模拟分析土地利用/覆被变化(LUCC)对不同重现期暴雨洪水事件的影响。结果表明,流域内1985—2003年土地利用变化引起不同重现期洪水过程与洪水量级发生改变,其中,洪量和洪峰均增加,洪量较洪峰变化明显。LUCC对小洪水过程影响更明显,5年一遇以上洪水的洪峰和洪量分别平均增加3%和7.6%,而小于2年一遇洪水的洪峰和洪量分别平均增加5.41%和11.91%。同时,LUCC使100年、50年和25年一遇洪水重现期分别提前了15、6a和2a,即其对量级最高的特大洪水的重现期影响最大。此外,不同的土地利用转变方式对洪水的影响程度不一,其中,林地向裸地转变对洪水影响最大,林地向灌草地转变次之,林地向耕地变化对洪水影响最小,且这种差异性在低重现期洪水表现更明显。     

基于土地利用变化的祁连山地区生态系统服务价值演化分析

祁连山生态环境保护是建设我国西部生态安全屏障的关键环节,而核算祁连山生态系统服务价值是制定合理有效的生态环境保护措施的有力依据。然而受气候变化和人类活动的共同影响,祁连山地区生态环境问题依旧突出,亟需对该地区生态系统服务价值开展研究以服务后期生态环境建设。基于此目的,使用1990-2020年祁连山地区土地利用数据,运用土地利用动态度、土地利用转移矩阵揭示该地区土地利用变化规律。并使用生态系统服务价值评估模型测算了祁连山地区生态系统服务价值,探究了其动态变化过程,并明确了各土地利用类型与生态系统服务价值变化之间的内在联系。结果表明:(1)1990-2020年,草地和荒漠是祁连山地区最主要的土地利用类型,单一土地利用动态度分别为水域 > 湿地 > 耕地 > 荒漠 > 草地 > 林地。草地和耕地以及草地和荒漠相互转化成为该地区最主要的土地利用变化特征;(2)祁连山地区生态系统服务价值呈持续增加趋势,由1990年的7231.36亿元增加至2020年的7836.07亿元,在空间上呈现出东高西低的变化趋势。生态系统服务价值构成主体主要为水域、草地和林地,单项生态系统服务价值以水文调节和气候调节为主,反映了调节服务是祁连山地区生态系统的主要功能;(3)水域、草地和湿地这3种土地利用类型是近30年祁连山地区生态系统服务价值变化的主要贡献因子。1990-2020年,祁连山地区生态系统服务价值对土地利用的敏感性总体呈增加态势(1.48%-7.91%),土地利用变化对该地区生态系统服务价值的影响逐步增强。系统揭示了过去30年祁连山地区生态系统服务价值的演变及其与土地利用变化的内在联系,重点阐释了水域、草地、林地和湿地对该地区生态系统服务价值和生态环境保护的重要性,可为祁连山地区生态产品价值实现及生态保护管理等提供基础科技支撑。     

土地利用变化的时空分异特征及驱动机制——以北京市海淀区、延庆县为例

研究土地利用变化的时空分异规律和机制对认识人类活动在全球变化中的作用机制具有重要意义.选择北京市海淀区、延庆县作为研究区,利用1992、2002年的遥感影像数据,采用转移矩阵法和多元线性回归法,分析了1992～2002年海淀区、延庆县土地利用变化的时空分异特征及其驱动机制.研究表明:①1992到2002年间,海淀区、延庆县土地利用变化的差异主要表现在:海淀区建设用地扩展速度明显高于延庆县,且内部改造强烈;延庆县农业用地面积减少程度明显低于海淀区,且有明显的内部结构调整;海淀区原有建设用地开始转变为林地. ②1992到2002年间,海淀区土地利用变化主要外在驱动力包括人口增长、第二产业(高新技术)、第三产业(房地产)的发展及北京市总体规划政策;最主要内在因素为前期土地利用方式;延庆县土地利用变化的主要外在驱动力包括非农业人口的增长、第三产业(旅游业)的发展、农业结构调整及生态建设;最主要内在因素为地形因素. ③海淀区土地利用变化是政策主导,延庆县土地利用变化是经济发展主导.     

On the role of small mammals in mediating climatically driven vegetation change

Biotic and abiotic processes jointly influence natural systems, yet opportunities to integrate studies of both processes are uncommon. For two decades we have excluded different subsets of the small mammal community from a series of plots near a grassland-desert ecotone in the northern Chihuahuan Desert. These studies spanned a period of historically high winter rainfall, allowing us to distinguish the effects of climate and small mammals on the composition and patch structure of vegetation. Removal of only kangaroo rats ( Dipodomys ) or of all small mammals led to increased cover of large herbaceous vegetation. The size of vegetative patches increased in all plots but this increase was three times greater where all rodents were removed. Thus, the activity of small mammals that forage under and near shrub canopies appear to significantly inhibit the expansion of existing vegetative patches, and may have a stronger influence on habitat structure than previously recognized.     

Bat responses to climate change: a systematic review

Understanding how species respond to climate change is key to informing vulnerability assessments and designing effective conservation strategies, yet research efforts on wildlife responses to climate change fail to deliver a representative overview due to inherent biases. Bats are a species-rich, globally distributed group of organisms that are thought to be particularly sensitive to the effects of climate change because of their high surface-to-volume ratios and low reproductive rates. We systematically reviewed the literature on bat responses to climate change to provide an overview of the current state of knowledge, identify research gaps and biases and highlight future research needs. We found that studies are geographically biased towards Europe, North America and Australia, and temperate and Mediterranean biomes, thus missing a substantial proportion of bat diversity and thermal responses. Less than half of the published studies provide concrete evidence for bat responses to climate change. For over a third of studied bat species, response evidence is only based on predictive species distribution models. Consequently, the most frequently reported responses involve range shifts (57% of species) and changes in patterns of species diversity (26%). Bats showed a variety of responses, including both positive (e.g. range expansion and population increase) and negative responses (range contraction and population decrease), although responses to extreme events were always negative or neutral. Spatial responses varied in their outcome and across families, with almost all taxonomic groups featuring both range expansions and contractions, while demographic responses were strongly biased towards negative outcomes, particularly among Pteropodidae and Molossidae. The commonly used correlative modelling approaches can be applied to many species, but do not provide mechanistic insight into behavioural, physiological, phenological or genetic responses. There was a paucity of experimental studies (26%), and only a small proportion of the 396 bat species covered in the examined studies were studied using long-term and/or experimental approaches (11%), even though they are more informative about the effects of climate change. We emphasise the need for more empirical studies to unravel the multifaceted nature of bats' responses to climate change and the need for standardised study designs that will enable synthesis and meta-analysis of the literature. Finally, we stress the importance of overcoming geographic and taxonomic disparities through strengthening research capacity in the Global South to provide a more comprehensive view of terrestrial biodiversity responses to climate change.     

广西滨海区域景观格局分析及土地利用变化预测

研究滨海湿地景观动态及其发展趋势对于维持沿海地区可持续发展具有重要意义。利用移动窗口法分析广西滨海湿地景观格局时空变化,同时提取珍珠湾、茅尾海和丹兜海典型区进一步分析景观变化趋势,最后采用土地利用变化模型(Land Change Modeler,LCM)预测区域未来的景观演化趋势。结果表明,2000—2014年间,草地、乔木园地和常绿阔叶灌木林面积减少,而工业用地面积明显增加。研究区总体的景观异质性变化不大,破碎化趋势不明显。比较景观格局指数发现,边缘密度和多样性指数的空间分布特征相似,多样性指数较大的区域,边缘密度也大,并且多集中于珍珠湾、茅尾海和研究区的中东部。3个典型区的格局变化趋势相似,景观多样性指数降低而均匀度增加,其中,湿地斑块数目减少且所占面积比也减少。LCM模型结果表明,至2020年,草本湿地与森林灌丛湿地面积进一步降低,而工业用地和居民区则持续增长;其中,3个典型区土地利用变化均受到了工业发展的影响,以珍珠湾土地利用动态度最高,茅尾海其次,而丹兜海最小。当前,区域景观的变化明显降低了湿地植被的质量,加强湿地植被保护,限制工业区域的无序发展是维持区域生境完整和安全的有效途径。     

云南省抚仙湖和杞麓湖流域土地利用变化对水质的影响

基于遥感技术和相关性分析方法对云南省2个典型高原湖泊抚仙湖和杞麓湖流域土地利用与湖泊水质关系进行了研究.结果表明:1989-2005年2个流域森林(灌丛)和建筑用地大量增长,荒地和农田有所减少,杞麓湖的污染程度比抚仙湖严重,2个湖泊的水质都呈下降趋势;湖滨200 m左右的缓冲带变化明显,且比流域其它土地利用变化对水质影响更大;城镇化和密集的农业耕作产生的面源污染是影响湖泊水质状况持续下降的重要因素,2个湖泊流域的土地利用结构不同也导致二者之间水质的差异.