Persistence of Gunnison’s prairie dog colonies in Arizona, USA

Although the five species of prairie dogs (Cynomys spp.) are recognized as important components of grassland ecosystems in western North America, they have experienced major population declines due to poisoning, outbreaks of sylvatic plague, recreational shooting, and habitat conversion. From May 2000 to October 2001, we investigated 270 colonies of Gunnison’s prairie dog (Cynomys gunnisoni) in Arizona. Because these colonies were classified as active in previous surveys (1987, 1990-1994, 1998), we were able to examine their persistence. Most (70%) of the colonies became inactive between the initial and recent surveys, with colony extinctions spanning our study area. Colony persistence was positively associated with the persistence of the nearest neighboring colony but was not associated with major vegetation type, distance to nearest neighboring colony, or initial size of the colony. The amount of area occupied by individual colonies varied between surveys, sometimes dramatically. We found little evidence that the reduction in active colonies was due to poisoning, recreational shooting, or habitat conversion. Rather, direct and indirect evidence suggest plague is the primary factor negatively impacting Gunnison’s prairie dog populations in Arizona. Currently, there is no way to control or prevent plague outbreaks in Gunnison’s prairie dog populations. To mitigate the effects of localized plague outbreaks on the overall population of this species, we suggest that Gunnison’s prairie dog be reintroduced to public lands throughout its historical range.     

拉西瓦水电站建设对区域景观格局与生境质量的影响

评价水电站建设对景观格局与生境质量的影响对改善当地生态环境质量、减少水土流失具有重要意义。以拉西瓦水电站周边区域为研究区,基于2000年、2005年、2010年、2015年土地利用和DEM等数据,利用移动窗口法分析水电站建设各时期景观格局指数的时空演变规律,结合InVEST模型研究生境质量的时空分布特征,探究水电站建设对周边区域景观格局与生境质量造成的影响。在此基础上,采用空间自相关方法分析生境质量的时空聚集模式,探讨高原地区水电站建设对周边区域生境质量时空聚集造成的影响。结果表明:(1)在2005—2010年水电站建设中期,景观格局指数空间分布发生明显变化,2000—2005年水电站建设前期与2010—2015年水电站建设后期几乎不变。(2)研究区的生境质量数值为0.3～0.7,在2005—2010年水电站建设中期,"中等"生境质量的面积占比由35.15%变成45.26%,"良好"生境质量的面积占比由48.23%变成40.28%。(3)2000年、2005年、2010年、2015年4期生境质量的Moran’s I均为正值,在空间上呈现非随机性,"高—高"空间聚集主要为河流与裸土地地区,"低—低"空间聚集为稀疏草地与建设用地地区,2005—2010年在水电站位置的西北区域,"不显著"空间聚集转为"低—低"空间聚集。     

Landscape effects on black-tailed prairie dog colonies

Black-tailed prairie dogs (Cynomys ludovicianus) increasingly compete for available habitat with human development in the Colorado Front Range. Because the effects of increased urbanization on prairie dog colonies are unknown, we studied how landscape context affects prairie dog density in Boulder County, Colorado, USA. We used burrow density as a proxy for prairie dog density because these variables were correlated at our study sites (r=0.60). Using remotely sensed data and a GIS, we quantified percent urbanization, road density, and the percentage of other prairie dog colonies in the surrounding landscape at 200, 1000, and 2000 m from the perimeter of 22 prairie dog colonies, and compared burrow density with each landscape variable at each scale. We also calculated Akaike's information criterion (AIC) to determine the most parsimonious models predicting burrow density. Ranges of burrow densities and prairie dog densities in Boulder County were higher than in other studies using similar methodology. Within Boulder County, burrow density was significantly higher in colonies surrounded by greater density of roads. The degree to which prairie dog colonies were immediately surrounded by unsuitable habitat, i.e. the “boundedness” of the colony, was negatively correlated with colony area and positively correlated with burrow density. A model based on boundedness, the density of roads at the 2000 m scale, and the amount of prairie dog colonies at the 200 m scale explained 73% of the variance in prairie dog burrow density. However, a non-linear model including boundedness and the squared term of road density at the 2000 m scale had the lowest AIC value of all linear and non-linear models, indicating a possible threshold effect of urbanization on prairie dog density. Urbanization may have several implications for prairie dog persistence. Increased prairie dog density in urbanized landscapes may be related to the Refuge effect, i.e. decreased predator abundance. If higher prairie dog density increases competition for available resources, habitat quality may decline leading to population decline in highly urbanized landscapes. Furthermore, if dispersal is reduced in urbanized landscapes, then these colonies may not be recolonized after local extirpation from plague epizootics. Alternatively, urbanized colonies may be effectively isolated from plague vectors and reservoir hosts, which could result in a lower frequency of plague epizootics when compared to non-urbanized colonies.     

Beaver (Castor canadensis) mitigate the effects of climate on the area of open water in boreal wetlands in western Canada

Shallow open water wetlands provide critical habitat for numerous species, yet they have become increasingly vulnerable to drought and warming temperatures and are often reduced in size and depth or disappear during drought. We examined how temperature, precipitation and beaver (Castor canadensis) activity influenced the area of open water in wetlands over a 54-year period in the mixed-wood boreal region of east-central Alberta, Canada. This entire glacial landscape with intermittently connected drainage patterns and shallow wetland lakes with few streams lost all beaver in the 19th century, with beaver returning to the study area in 1954. We assessed the area of open water in wetlands using 12 aerial photo mosaics from 1948 to 2002, which covered wet and dry periods, when beaver were absent on the landscape to a time when they had become well established. The number of active beaver lodges explained over 80% of the variability in the area of open water during that period. Temperature, precipitation and climatic variables were much less important than beaver in maintaining open water areas. In addition, during wet and dry years, the presence of beaver was associated with a 9-fold increase in open water area when compared to a period when beaver were absent from those same sites. Thus, beaver have a dramatic influence on the creation and maintenance of wetlands even during extreme drought. Given the important role of beaver in wetland preservation and in light of a drying climate in this region, their removal should be considered a wetland disturbance that should be avoided.     

The conservation status of Townsend's shearwater Puffinus auricularis auricularis

Townsend's shearwater (Puffinus auricularis auricularis) is an endangered seabird endemic to the Revillagigedo Archipelago. It nested on Socorro, Clarion, and San Benedicto Islands. It was extirpated by the Barcena volcano on San Benedicto in 1952, and there are no recent indications of nesting. Introduced mammals—pigs and rabbits—preyed on them and destroyed habitat at Clarion; shearwaters were extirpated by 1988, and no breeding attempts have been reported since. Our results confirm that Socorro holds the last breeding grounds. We found breeding colonies above 800 m and a minimum population of 1100 individuals. This represents a significant reduction in distribution and population size. Intensive cat predation at Socorro could potentially kill ca. 350 females per season, and sheep progressively destroy nesting areas. Population projections suggest that demographic instability could occur in less than 100 years under severe predation and habitat degradation. Only low predation rates would allow population persistence for more than 150 years in spite of a declining population. Thus, the immediate eradication of all introduced mammals is necessary to prevent the extinction of this seabird.     

汉江上游1988-2007年间景观格局变化分析

为研究陕西省境内汉江流域水电开发后区域景观格局时空演变,根据1988,2000和2007年汉江上游地区遥感影像,通过遥感解译,利用GIS缓冲区分析分别研究了汉江上游整体和500,1 000,5 000m缓冲区内景观格局变化。结果表明:(1)汉江上游1988年以来水域呈持续增加趋势,耕地呈现持续"落势",全时段景观格局处于不平衡态,双向转换较频繁。但有向着有利于区域生态改善方向转变的趋势。(2)从景观破碎化、景观形状和景观多样性3个角度分析了研究区景观格局变化,1988-2000年该区景观格局破碎化程度增加,形状趋向复杂,景观趋向多样化;2000-2007年该区景观破碎化程度减小,形状趋向规则化,景观多样性减小,表明景观格局向着有利于区域生态改善的方向转变。(3)汉江上游水电7级梯度开发对沿河500m缓冲区内景观格局影响最显著。     

No evidence of a plant extinction debt in highly fragmented calcareous grasslands in Belgium

Long transient times in response to decreasing habitat area and increasing isolation may cause the present plant species distribution to reflect the historical rather than the present landscape configuration, resulting in a so-called extinction debt. To investigate how plant species richness is shaped by both present and historical landscape configuration and local environmental conditions in fragmented calcareous grasslands, 64 sites in Southern Belgium were surveyed for their total species richness and environmental characteristics. Species were subdivided in specialist and generalist groups and the former were clustered into emergent groups (EGs) according to 16 relevant life-history traits. Four specialist emergent groups were derived: orchids, rosette species, annuals and half-rosette species. Both specialist and generalist species richness increased with present fragment area, while present fragment connectivity only affected the number of specialist species. This trend was maintained for most EGs, although habitat area was mostly more important than connectivity. All species groups responded to an insolation gradient, except EGs of rosette and annual species. Differential response to fragmentation among emergent groups could be interpreted in terms of dispersal and persistence traits. No relation between species richness and historical area or connectivity was found, making an extinction debt unlikely. Hence, present-day variation in plant species diversity seems to be no legacy of past landscape configuration. Our results clearly indicate that plant species may be quickly lost in response to new fragmentation events. To restore plant diversity, management should focus both on mitigating landscape fragmentation and restoring habitat quality.     

Extirpation, colonization, and habitat dynamics of a keystone species along an urban gradient

Using 5 years of patch occupancy data for 384 habitat fragments, we evaluated population and habitat dynamics of the black-tailed prairie dog in urban habitat remnants in the rapidly developing landscape of Denver, CO, USA. Specifically, we evaluated the landscape factors, including fragment area, age, and connectivity, that characterize the habitat fragments most likely to be colonized by prairie dogs, as well as those experiencing local extinctions. In addition, we determined which patch types were most often removed by land development. Sites in proximity to colonies were more likely to be colonized by prairie dogs. Local extinctions were most common on isolated colonies, and older and more isolated colonies were more likely to be extirpated by human activity. In general, smaller and older habitat patches were at the highest risk of being lost to land development. Our results provide observations of dynamic changes to the distribution of a potential keystone species in an urban area, which can be used to inform island biogeographic and metapopulation models for wildlife persistence in developing landscapes. Although populations are currently in decline, most local extinctions are the direct result of human activity, and we suggest that prairie dogs in this area can persist with appropriate management.     

Anthropogenic determinants of primate and carnivore local extinctions in a fragmented forest landscape of southern Amazonia

Habitat fragmentation has been shown to influence the abundance, movements and persistence of many species. Here, we examine the effects of forest patch and landscape metrics, and levels of forest disturbance on the patterns of local extinction of five primate and 14 carnivore species within 129 forest patches in a highly fragmented forest landscape of southern Brazilian Amazonia. Classic habitat area effects were the strongest predictors of species persistence, explaining between 42% and 55% of the overall variation in primate and carnivore species richness. Logistic regression models showed that anthropogenic disturbance, including surface wildfires, timber extraction and hunting pressure, had detrimental effects on the persistence of some species over and above those of fragment size. Different species ranged in their responses from highly sensitive to highly tolerant to forest fragmentation. Patterns of local extinction documented here were by no means chance events, and the nestedness of the overall species-by-site matrix was highly nonrandom in terms of the sets of species extirpated from the most to the least species-rich forest patches.     

喀斯特石漠化生态系统服务价值对生态治理的响应——以贵州花江峡谷石漠化治理示范区为例

为揭示喀斯特石漠化生态系统服务功能价值对生态治理的响应,以贵州花江峡谷为例,将提供产品、涵养水源、保持土壤、土壤肥力、固碳释氧5项功能作为服务价值评估指标,选择生态治理两个时段(前期2000—2005年、后期2005—2010年),基于实测与调查数据,采用物质量和价值量相结合的方法对生态系统服务价值进行了估算。研究区10 a的生态系统类型变化过程中,发生转变的面积14.29 hm2,占总面积的27.7%。其中林分、灌丛、其他生态系统面积有所增加,而耕地、裸岩荒地面积大幅度减少。2000—2005年研究区生态系统类型发生转变的面积11.83 hm2,占土地总面积的22.9%,主要变化区域集中在河岸两侧实施退耕还林区域。2005—2010年研究区生态系统类型发生转变的面积仅占总面积的4.8%,与上一阶段相比转变强度明显降低,变化区域较为分散。研究区生态治理后系统服务价值显著增加,2000—2010年共增加9.61×107元,其中前期增额占18.2%,后期占81.8%。前期年均增长3.49×106元,后期年均增长1.57×107元,后期生态服务价值增长更为显著。其中固定CO2、释放O2价值,产品供给价值和土壤肥力都是服务价值主要组成部分。功能价值的增加一方面源于服务价值低的生态系统向服务价值高的演变(10年间研究区耕地和裸岩荒地向经济生态系统转出868.60 hm2),另一方面归功于生态系统内部服务价值的增加,其贡献率大于80%,是驱动服务价值变化的主导因素。生态治理后生态系统类型间发生明显的空间转变,转变强度、场所与所实施生态治理工程的数量、区域密切相关。治理后生态系统类型间发生转变时间响应较快(前期转变面积占总转变面积的83.0%),但主要服务功能恢复期后才大幅度增加(后期增加功能价值占总增额的81.8%),相比较服务价值变化响应有一定滞后性。     

Effect of the landscape context on the density and persistence of a predator population in a protected area subject to environmental variability

Protected areas are the most important tool for the conservation of biodiversity. However, many species are area-demanding and their populations seldom meet their space requirements in reserves. In this context, the unprotected exterior becomes an important part of their home range, and variations in habitat quality of the surroundings of a protected area might affect the dynamics of populations. Using a spatially explicit simulation model, we studied the effect of the surrounding landscape of a protected area on the density and persistence of a predator population inhabiting inside the reserve in different conditions of environmental variability. We simulated individuals of a predator population, their herbivorous prey and a vegetative substrate in a landscape comprised of a square protected area and different types of habitat quality outside the reserve. We studied the combination of three substrate qualities of protected area (inside) with three of the landscape context and three levels of variability of productivity. Our results showed that there were strong effects of both the relative quality of the surrounding landscape and of the environmental variability on the density and persistence of the simulated population inside the protected area. More importantly, we showed that complex patterns emerge when spatial heterogeneity and temporal variability interact with population dynamics. Specifically, under high environmental variability, when the protected area had a high habitat quality, the highest population persistence was not attained when the exterior was also of high quality, but when the surroundings had an intermediate quality. The latter result suggests that, under the mentioned conditions, small enhancements in the quality of the matrix may have, for some species, better effects on increasing persistence in small reserves than large and costly enhancements.     

南京市江北地区景观格局演变及驱动力分析

以南京市江北地区为研究对象,基于遥感及地理信息技术,利用江北地区1988年、1995年、2000年和2006年TM5数据以及2013年TM8数据,运用景观生态学原理,选取斑块数量、平均斑块面积、边缘密度、平均分维度指数、香农多样性指数、香农均匀度指数等进行分析,探讨南京市江北地区近25年景观格局演变特征及驱动力。结果表明:1988—2013年江北地区景观格局发生较大变化,城建用地、林地面积增加,耕地面积减少,其他略有波动;在人类干扰作用下,斑块聚合度与斑块结合度呈现下降趋势,多样性指数与均匀度指数呈现上升趋势,破碎化程度增加。人口增加、经济增长、工业发展及产业结构调整是南京市江北地区景观格局演变的主要驱动力。     

The relative importance of patch habitat quality and landscape attributes on a declining steppe-bird metapopulation

Metapopulation theory is one of the most popular approaches to identify the factors affecting the spatial and temporal dynamics of populations in fragmented habitat networks. Habitat quality, patch area and isolation are mainly focused on when analyzing distribution patterns in fragmented landscapes. The effects of landscape heterogeneity in the non-occupied matrix, however, have been largely neglected. Here, we determined the relative importance of patch quality and landscape attributes on the occurrence, density and extinction of the Dupont’s lark (Chersophilus duponti), an endangered steppe passerine whose habitat has been extremely reduced to highly isolated and fragmented patches embedded in a mainly unsuitable landscape matrix. Habitat patch quality, measured in terms of vegetation structure, grazing pressure, arthropod availability, predator abundance, and inter-specific competition, did not affect occurrence, density or extinction. At the landscape scale, however, the species’ occurrence was principally determined by the interactions among patch size, geographic isolation and landscape matrix. Isolation had the main independent contribution to explaining the probability of occurrence, followed by landscape matrix composition and patch size. The species’ density was negatively correlated to patch size, suggesting crowding effects in small fragments, while extinction events were exclusively related to isolation. Our findings suggest that landscape rather than local population characteristics are crucial in determining the patterns of distribution and abundance of non-equilibrium populations in highly fragmented habitat networks. Consequently, conservation measures for these species should simultaneously involve patch size, isolation and landscape matrix and apply to the entire metapopulation rather than to particular patches.     

山东沿海地区土地利用和景观格局变化

为分析和预测山东省沿海区域土地利用和景观格局变化,该文将景观格局指数作为评价土地利用变化模拟模型的基本指标;基于RS和GIS技术分析2000-2010年土地利用和景观格局的变化特征,并尝试CA-Markov模型预测土地利用变化,发现其在景观格局预测方面的不足,因而探索和提出Spatial-Markov模型,该模型不仅适合于土地利用变化模拟,也适合于景观格局过程分析。具体包括:1)基于2000、2005和2010年的Landsat影像进行土地利用分类,分析10a间土地利用和景观格局的变化特征,表明:耕地面积不断减少,城镇和农村居民点用地不断扩张而占用大量耕地,草地等又不断开垦为耕地;区域景观格局破碎化趋势显著,人为干扰加剧,各种景观类型的分布向均匀化发展;2)基于Logistic-CA-Markov模型,以11个变量、2000和2005年土地利用分类图为基础,模拟的2010年土地利用图与观测值相比较,虽然得到的Kappa系数较高(0.8530),但难以支持对景观格局特征的预测和分析;3)提出Spatial-Markov模型,基于2000和2005年土地利用分类图模拟2010年土地利用,模拟结果的Kappa系数高达0.8872,且景观格局指数也与观测值非常接近,因此,选择该模型预测2015和2020年的土地利用和景观格局;4)预测结果表明,2010-2020年间耕地面积将继续减少,城镇、农村居民点将继续保持快速增长的态势;景观尺度除了分形维数,其他指数保持2000-2010年间的变化趋势,而在类型尺度,除水域和未利用地外,各种景观类型多个景观指数将总体保持原有的变化趋势。该研究可为山东沿海区域土地利用规划提供参考,并为土地利用预测研究提供了一种新的方法。     

21世纪初科尔沁沙地沙漠化对区域气候变化的响应

利用2000—2013年生长季MODIS-NDVI时间序列遥感数据和降水、气温、蒸发和风速等气象数据,研究21世纪初科尔沁沙地沙漠化动态变化及其对区域气候变化的响应关系。结果表明:21世纪初,科尔沁沙地沙漠化经历了逆转-发展-逆转的过程,轻度和中度沙漠化土地面积呈显著下降趋势,重度和极重度沙漠化土地面积呈下降趋势但不显著。未沙漠化土地主要分布在研究区西北部,轻度和中度沙漠化土地广泛分布在研究区南部、东部和北部,重度和极重度沙漠化土地主要分布在西南部。2000—2013年,科尔沁沙地降水量呈上升趋势,气温、蒸发量和起沙风日数呈下降趋势,斜率分别为8.34 mm/a、-0.04℃/a、-23.56 mm/a和-1.7 d/a,其中蒸发量和起沙风日数下降趋势较为显著;近14 a来,科尔沁沙地沙漠化主要受水热条件的影响,尤其是在2000—2005年、2009—2013年2个时期,降水增多、蒸发减少,区域气候较湿润,研究区沙漠化2次逆转;此外,沙漠化受气候影响具有地域差异性,受气候影响较大的地区主要集中在研究区东部和东南部地区。研究可为科尔沁沙地沙漠形成机理分析及沙漠化防治工作提供理论依据。     

Alleviating impacts of anthropogenic activities by traditional conservation measures: can a small reef reserve be sustainedly managed?

Zoning schemes that are becoming an important management tool in large marine reserves, are difficult to implement in small reef areas. At the 3.4 km long reef of Eilat (Red Sea), a small (ca. 350 m of coastline) enclosure strategy has been enforced since 1992, while the remaining reef was left open to intense human activities. Here we have investigated for 2.5 y three populations of the branching coral Stylophora pistillata (3605 colonies) in a locality within the enclosed area (site NR) and in two areas open to the public, by tossing random quadrats at the shallow lagoonar zone (0.5-1.5 m depth). In the two open sites we found significantly higher levels of colony breakage (14-34% vs. 4-9% in the enclosed site), lower partial mortality levels of colonies (in the first 1.5 y; 7-9% vs. 23-30% at NR), higher recruitment (up to 3.0 vs. up to 0.9 colonies/m 2), 50% reduction in coral life span (10 vs. 20 y) and an estimated extinction period of 9-10 y for new cohorts as compared to >20 y in the enclosed site. Average colony size and maximal colony size were about half in the open sites. Live coverage fluctuated widely in all sites but was 3 times higher in the enclosed area (1.0-3.0% vs. 0.3-1.1%). Log-transformed size frequency distributions revealed, at the open sites, a shift from small towards medium-size classes and at the enclosed site, a shift from larger to medium size classes. We conclude that the enclosure of a limited core zone, although improved some ecological parameters, was not sufficient to compensate for stress imposed by anthropogenic activities. It is suggested to employ active restoration approaches, such as the “gardening concept”, as supplementary management tools.     

2000-2020年昌吉州东部平原区地下水位埋深对土地利用及干旱时空演变的动态响应

联合土地利用与覆被变化及气象干旱综合分析区域地下水位埋深变化及其动态响应关系,明晰地下水位埋深变化的阶段性主导因素,对地下水超采地区综合治理和地下水资源有效管控具有现实意义。选取昌吉州东部平原区2000-2020年78眼地下水监测井月尺度地下水位埋深数据资料及5期遥感影像数据并结合同期多尺度标准化降水蒸散发指数SPEI,分析不同时空尺度地下水位埋深对土地利用/覆被变化及SPEI的动态响应规律,探讨研究区土地利用变化与干旱变化趋势对地下水埋深变化的综合影响。结果表明：研究区21年间地下水位埋深表现出不显著变化(2000-2005年)-显著增大(2005-2014年)-变缓(2014-2017年)-持续增大(2017-2020年)的变化特征,整体呈持续增大动态趋势,空间分布呈北向南逐渐增大特征;同期土地利用类型面积发生了显著变化,耕地为其主要的土地利用类型,面积呈持续增加趋势,分形维数呈现出先降低(2000-2005年)后升高(2005-2010年)再降低(2010-2020年)的变化特征;SPEI年际动态变化呈显著干旱趋势变化特征,年尺度序列在2012年、2017年发生突变,2016年开...     

Agricultural intensification and loss of matrix habitat over 23 years in the West Wimmera, south-eastern Australia

The global trend toward more intensive forms of agriculture is changing the nature of matrix habitat in agricultural areas. Removal of components of matrix habitat can affect native biota at the paddock and the landscape scale, particularly where intensification occurs over large areas. We identify the loss of paddock trees due to the proliferation of centre pivot irrigation in dryland farming areas as a potentially serious threat to the remnant biota of these areas. We used a region of south-eastern Australia as a case study to quantify land use change from grazing and dryland cropping to centre pivot irrigation over a 23-year period. We also estimated rates of paddock tree loss in 5 representative landscapes within the region over the same period. The total area affected by centre pivots increased from 0 ha in 1980 to nearly 9000 ha by 2005. Pivots were more likely to be established in areas which had originally been plains savannah and woodlands containing buloke (Allocasuarina luehmannii), a food source for an endangered bird. On average, 42% of paddock buloke trees present in 1982 were lost by 2005. In the two landscapes containing several centre pivots, the loss was 54% and 70%. This accelerated loss of important components of matrix habitat is likely to result in species declines and local extinctions. We recommend that measures to alleviate the likely negative impacts of matrix habitat loss on native biota be considered as part of regional planning strategies.     

赣州市生境质量和景观格局间时空非平稳性关联

在城市化的高速推进造成景观破碎、威胁生境质量的大背景下,赣州市较好地实现了经济发展与生态保护并行。为探明赣州市景观格局对生境质量的驱动机理,回答“怎样的景观格局有利于生态保护”这一问题,该研究以赣州市为研究区,对其2000—2020年的生境质量进行空间测度并分析其时空跃迁动态特征;分析其景观格局演变特征,并基于时空地理加权回归模型（geographically and temporally weighted regression,GTWR）探明二者关联机制。结果表明：赣州市生境质量呈现“四周高,中部低”的空间分布特征,2000—2020年整体均处于较高水平,呈现积极协同进步的空间动态特征;赣州市景观格局维持在较稳定状态,人造地表扩张优先占用非林非水地类,且与水域增量存在空间伴随;生境质量与景观格局间关联呈现显著的时空非平稳性特征;散布与并列指数（interspersion juxtaposition index ,IJI）显示人造地表、林地和水域交错分布可能降低人造地表对生境质量的负向影响。该研究以提升生境质量为目标,探明了10 km×10 km格网尺度下赣州市各景观格局指数的最优驱动阈值区间,人造地表总面积占比全域应控制在0.68%之内,最大斑块占林地总面积比不宜低于9.8%,且林地总面积占比全域应控制在7.8%之内,斑块IJI指数应大于20%,草地和水域斑块IJI指数应控制在60%内以及超出13%。研究结果可为对国土空间规划和其他区域的生态管理决策提供参考。     

生态移民安置区土地利用景观格局的稳定性研究——以宁夏回族自治区红寺堡区为例

[目的]探讨2005,2010和2015年3个时期红寺堡生态移民安置区土地利用景观格局特征,根据景观格局指数分析景观格局稳定性的变化,为生态移民后续产业发展提供参考。[方法]通过构建土地利用景观格局稳定性评价模型,利用红寺堡区2005,2010和2015年3期数据,从景观类型组成、斑块特征和景观异质性3个方面分析景观格局稳定性,并对主因子进行探测。[结果]近10a来,红寺堡区土地利用景观格局发生了较大变化,主要景观间的转换较为频繁,且表现为单向转换的特征;整体的景观格局稳定性下降,草地和耕地是红寺堡区主要的景观类型,是调控土地利用格局稳定性的主要组成部分。地理探测结果表明,面积、面积比、斑块个数、斑块数比、斑块密度、平均值和标准差在3个时期都对景观稳定性有较大影响,而其他指标的变动较明显,波动较大,整体上对景观稳定性的影响较小。[结论]2005—2015年,红寺堡区土地利用景观格局稳定性变化明显,不同时期、不同阶段的土地利用景观格局的稳定性变化也不相同。