Predation of potential insect pests in oil palm plantations,rubber tree plantations,and fruit orchards

In human‐modified landscapes, important ecological functions such as predation are negatively affected by anthropogenic activities, including the use of pesticides and habitat degradation. Predation of insect pests is an indicator of healthy ecosystem functioning, which provides important ecosystem services, especially for agricultural systems. In this study, we compare predation attempts from arthropods, mammals, and birds on artificial caterpillars in the understory, between three tropical agricultural land‐use types: oil palm plantations, rubber tree plantations, and fruit orchards. We collected a range of local and landscape‐scale data including undergrowth vegetation structure; elevation; proximity to forest; and canopy cover in order to understand how environmental variables can affect predation. In all three land‐use types, our results showed that arthropods and mammals were important predators of artificial caterpillars and there was little predation by birds. We did not find any effect of the environmental variables on predation. There was an interactive effect between land‐use type and predator type. Predation by mammals was considerably higher in fruit orchards and rubber tree than in oil palm plantations, likely due to their ability to support higher abundances of insectivorous mammals. In order to maintain or enhance natural pest control in these common tropical agricultural land‐use types, management practices that benefit insectivorous animals should be introduced, such as the reduction of pesticides, improvement of understory vegetation, and local and landscape heterogeneity.     

Do exotic pine plantations favour the spread of invasive herbivorous mammals in Patagonia?

Changes in land use patterns and vegetation can trigger ecological change in occupancy and community composition. Among the potential ecological consequences of land use change is altered susceptibility to occupancy by invasive species. We investigated the responses of three introduced mammals (red deer, Cervus elaphus; wild boar, Sus scrofa; and European hare, Lepus europaeus) to replacement of native vegetation by exotic pine plantations in the Patagonian forest‐steppe ecotone using camera‐trap surveys (8633 trap‐days). We used logistic regression models to relate species presence with habitat variables at stand and landscape scales. Red deer and wild boar used pine plantations significantly more frequently than native vegetation. In contrast, occurrence of European hares did not differ between pine plantations and native vegetation, although hares were recorded more frequently in firebreaks than in plantations or native vegetation. Presence of red deer and wild boar was positively associated with cover of pine plantations at the landscape scale, and negatively associated with mid‐storey cover and diversity at the stand scale. European hares preferred sites with low arboreal and mid‐storey cover. Our results suggest that pine plantations promote increased abundances of invasive species whose original distributions are associated with woodlands (red deer and wild boar), and could act as source or pathways for invasive species to new areas.     

A review of the ecosystem functions in oil palm plantations,using forests as a reference system

Oil palm plantations have expanded rapidly in recent decades. This large‐scale land‐use change has had great ecological, economic, and social impacts on both the areas converted to oil palm and their surroundings. However, research on the impacts of oil palm cultivation is scattered and patchy, and no clear overview exists. We address this gap through a systematic and comprehensive literature review of all ecosystem functions in oil palm plantations, including several (genetic, medicinal and ornamental resources, information functions) not included in previous systematic reviews. We compare ecosystem functions in oil palm plantations to those in forests, as the conversion of forest to oil palm is prevalent in the tropics. We find that oil palm plantations generally have reduced ecosystem functioning compared to forests: 11 out of 14 ecosystem functions show a net decrease in level of function. Some functions show decreases with potentially irreversible global impacts (e.g. reductions in gas and climate regulation, habitat and nursery functions, genetic resources, medicinal resources, and information functions). The most serious impacts occur when forest is cleared to establish new plantations, and immediately afterwards, especially on peat soils. To variable degrees, specific plantation management measures can prevent or reduce losses of some ecosystem functions (e.g. avoid illegal land clearing via fire, avoid draining of peat, use of integrated pest management, use of cover crops, mulch, and compost) and we highlight synergistic mitigation measures that can improve multiple ecosystem functions simultaneously. The only ecosystem function which increases in oil palm plantations is, unsurprisingly, the production of marketable goods. Our review highlights numerous research gaps. In particular, there are significant gaps with respect to socio‐cultural information functions. Further, there is a need for more empirical data on the importance of spatial and temporal scales, such as differences among plantations in different environments, of different sizes, and of different ages, as our review has identified examples where ecosystem functions vary spatially and temporally. Finally, more research is needed on developing management practices that can offset the losses of ecosystem functions. Our findings should stimulate research to address the identified gaps, and provide a foundation for more systematic research and discussion on ways to minimize the negative impacts and maximize the positive impacts of oil palm cultivation.     

Interactions between changes in land cover and potential of ecosystem services in Lithuania at temporal and spatial scale

The growing interest in ecosystem services is mainly related to land use changes. The aim of the study is to analyse spatial-temporal changes in the capacity to supply of ES in Lithuania based on land use changes in 1990–2018. The results show some balance between loss and gains of ecosystem services capacity due to land use changes. Decrease in heterogenous agricultural areas had negative impact on provision of ecosystem integrity and services. Considerable increase in scrubland and herbaceous vegetation areas significantly increased the ecosystem service potential. The conversion of former agricultural land to less intensively managed ecosystems enhance the potential of valuable habitats for biodiversity and ecosystem services associated with natural grasslands, moors and heathland, transitional woodland shrubs. The urbanization process along with increase in urban fabric areas had little effect on ESs potential since artificial vegetated areas had compensated the loss of ESs due to increased areas of urbanized ecosystems. Despite the area of open spaces slightly increased, this led to decrease of provision of ESs. Temporal changes in overall ESs capacity indicated an increase in Lithuania over the last two decades. Given the observed dynamic context of land cover, the structure of ecosystem services may face potential threats from land use change due to urban development and agricultural activities.     

海南岛主要森林类型时空动态及关键驱动因子

天然林,橡胶林和浆纸林之间转化是海南岛森林生态系统演变的主要形式.以海南岛1988年(建省),1998年(提出生态省建设)和2008年(目前)3个年代的天然林,橡胶林和浆纸林遥感解译为基础,分析了三者的格局动态及关键驱动因子,得到以下结论:(1)1988-1998和1998-2008年间,天然林总面积呈现先明显增加(增加面积10.76万hm2),后明显减少(减少面积20.03万hm2)特点;橡胶林呈先小幅下降(下降面积7.14万hm2),后大幅度增加(增加面积20.03万hm2)的变化特点,浆纸林则一直呈增加的趋势;(2)三者年动态变化率在1998-2008年间最大(1.335％),1988-2008年间次之(0.965％),1988-1998年间最小(0.490％);(3)1988-1998年天然林空间范围转化呈内部增加,外部扩展的特征,增加的部分主要来自橡胶林和其他用地类型,同时,浆纸林空间转化呈局部增加和橡胶林呈局部减少的特点;1998-2008相比1988-1998年间,天然林空间范围呈外缘收缩,内部减少的特点,橡胶林和浆纸林则呈内外部都扩张的特点.类型间转化天然林向橡胶林,浆纸林和其他类型用地转化较明显;(4)不同时期的林地面积变化主要受政策,农业人口,农林产品市场价格等外在因素的作用,同时也受到道路,高程和坡度等内在因素的影响.最后,从林业监督,生态补偿,市场调节等角度提出海南省林业发展建议.     

基于LUCC的江苏省生态系统服务价值时空变化特征研究

江苏省作为资源环境容量有限但经济发展迅速的典型代表,在可持续发展背景下,开展土地利用变化、生态系统服务变化及其价值时空变化的研究,以期为缩小区域经济差异进行科学土地整治提供理论依据。首先基于1995-2015年间研究区经济发展重要时间节点的土地利用/覆被变化（LUCC）数据分析土地利用变化情况,然后引入评估计分理论动态研究生态系统服务变化,最后通过修正当量因子计算生态系统服务价值并应用空间自相关与热点分析方法研究其时空变化特征。结果表明：（1）耕地、建设用地和水体为研究区主要土地利用类型,总覆盖度达到90%以上;2005-2015年土地利用变化速度显著;苏南地区土地利用较为丰富。（2）对比各景观类型,森林是具有更多功能的生态系统;2015年功能属性总得分高于1995年,但生态功能得分由5分降至2分。（3）1995-2015年江苏省生态系统服务价值从1258.19亿元减少为1208.74亿元,苏南地区生态系统服务价值变化较大。据预测至2022年,生态系统服务价值会跌到1.35亿元。     

樟子松固沙林林水关系研究进展及对营林实践的指导

中国有着世界上最大面积的人工林, 如何维持人工林的可持续性已成为气候变化背景下需要面对的重大挑战。樟子松(Pinus sylvestris var. mongolica)以其抗旱、抗寒、耐贫瘠等优良特性成为中国北方生态治理中最主要的常绿针叶树种之一, 近70年来发挥了巨大的防风固沙与生态固碳功能。然而, 随着林分的生长与气候变化, 樟子松人工固沙林正经历着越来越严峻的环境胁迫, 部分地区出现了林分“早衰”或死亡的现象, 引起了人们对樟子松固沙林适应与应对气候变化能力的担忧。该文在回溯樟子松基本生物学特征与引种推广历史, 系统总结近年来樟子松林林水关系研究新成果的基础上, 全面分析了樟子松固沙林林水关系存在的主要矛盾, 并提出了基于林水关系相协调的林分经营措施的调整: 由倡导防护功能为主的单一目标向包含林分稳定性、生态固碳功能、可持续发展等多目标平衡方向调整; 由以沙地森林景观培育为主向以良好土壤生境培育为主的方向调整; 由倡导天然更新为主向以人工造林与天然更新相结合的世代更新方向调整。在立足于北方沙地脆弱生境与气候变化客观现实的基础背景下, 应坚持樟子松在固沙林生态系统演化过程中的先锋种与建群种地位, 基于“以水定绿”原则, 采取“隔行带伐+再造林”等方式开展林分密度动态调控, 促进林分向异龄林结构演化, 促进樟子松固沙林生态服务的优质化和生态固碳功能的最大化。     

Ecological and environmental effects of land use change in rapid urbanization: The case of hangzhou,China

Land use changes sharply under rapid urbanization, yet its ecological and environmental effects are often neglected in land use decisions. Using the case of Hangzhou, China, we analyze the ecological and environmental effects of land use changes, including ecosystem services value (ESV) and carbon emissions, based on Landsat TM images from 1995, 2000, 2005, 2010, and 2014. We found significant ecological and environmental effects of land use changes under rapid urbanization. The value of ecosystem services in Hangzhou decreased from 546.7 million USD in 1995 to 448.97 million USD in 2014, and the ratio of ESV to GDP decreased from 5.8% to 0.6%. The net carbon emissions associated with land use changes increased from 4.26 million tons in 1995 to 15.10 million tons in 2014, mainly due to the increase of built-up land carbon emissions and the decrease of forest land carbon sink. The ESV is unevenly distributed spatially and low ESV spread from the central to the peripheral area. We use scenario analysis to illustrate that economic growth and environmental protection could be coordinated by bringing ecological and environmental effects into land use decisions.     

Bird community responses to afforested eucalyptus plantations in the Argentine pampas

Land-use change driven by human population growth and economic activity will continue to impact both natural habitats and land currently being used for food, fiber, and fuel production. The effects of this conversion on economically important ecological services will in large part depend on how native biodiversity responds to these changes. We investigated how agriculture-related land use change influences the avian community in northeastern Argentina by examining common agricultural land uses (pasture/annual crops, young and mature large-scale eucalyptus plantations, mixed-use farms with citrus, blueberry and small stands of eucalyptus) and remnant native espinal savannas. In this region, afforested eucalyptus plantations represent a new land-use change from the land cover of pasture with intermixed annual crops that has dominated the region. In this mosaic, we used point counts to assess how avian diversity and community structure differed between land uses. Bird species richness was lowest in older plantations and highest in the espinal savanna, with the other land uses having intermediate richness. Abundance trends followed the same pattern, with low overall abundance in the plantations, intermediate levels for pasture/annual crops, and highest abundance in the espinal. Distinct bird community assemblages were strongly associated with each land use, and between young and mature eucalyptus stands. Birds can be useful indicators for biodiversity as a whole, and the depopulated and depauperate avian community within the eucalyptus plantations will likely lead to reduced provision of many ecosystem services in this region if the spatial extent of plantations continues to expand.     

西双版纳土地利用/覆盖变化与地形的关系

 土地利用/覆盖变化是全球变化研究的重要领域。该文利用6个时期的MSS/TM/ETM影像和1:50 000DEM数据分析了1976~2007年西双版纳地区不同地形下的土地利用/覆盖变化动态, 结果表明: 1)31年间, 该区土地利用/覆盖变化剧烈, 有林地面积由1976年的69.0%下降到2007年的43.6%, 橡胶园面积由1976年的1.3%增加到2007年的11.8%; 2)有林地在海拔1 600 m以下不断减少, 而橡胶园的海拔分布上限则持续增加, 由1976年的1 000 m上升至2007年的1 400 m, 面积在400~1 000 m处占优。农业用地主要分布在海拔400～600 m, 在600 m之上迅速减少; 3)各坡度带上的有林地面积逐年减少, 橡胶园则逐年增加, 而灌木林与旱地则先升后降; 橡胶园、农业用地等主要分布在坡度较缓的区域, 坡度越大, 有林地越多; 1988年后, 橡胶园面积在坡度5°以下基本保持不变, 但在坡度大于5°的区域持续扩张; 4)坡向对橡胶园与农业用地等分布的影响较大, 南坡的橡胶发展最为迅速, 且有向北坡发展的趋势。有林地在北坡分布比例较大, 旱地在北坡分布比例较小。人口增加与橡胶园和茶园等经济种植园的不断扩展是导致西双版纳土地利用/覆盖变化的直接因素。要实现西双版纳的可持续发展, 必须控制经济种植园的盲目扩张, 科学合理垦殖, 保护热带森林。     

A landscape‐based approach for assessing spatiotemporal impacts of forest biomass‐based electricity generation on the age structure of surrounding forest plantations in the Southern United States

Forest plantations support several ecosystem services including biodiversity conservation. Establishment of a forest biomass‐based industry could significantly change the age structure of forest plantations located in its vicinity and thus, could lead to a possible loss of biodiversity. Therefore, this study assesses spatiotemporal impacts of a forest biomass‐based power plant on the age structure of surrounding forest plantations at landscape level. A cellular automata approach was adopted and interactions between economic objectives of forest landowners and a power plant owner punctuated by forest growth and management characteristics were considered. These spatiotemporal impacts were jointly assessed for four separate scenarios and four different power plant capacities using appropriate landscape‐level indices. Slash pine (Pinus elliotti L.) was selected as a representative species. Results indicate that the age structure of surrounding forest plantations continuously fluctuates with respect to each year of power plant operation. However, the age structure, once disturbed, never becomes comparable to the original age structure. We also found that the mature plantations were harvested during early years of power plant operation and were never observed again for the remaining years of power plant operation. This was particularly true for high capacity power plants. Similarly, high value of selected spatial index at the end of power plant life for a high capacity power plant relative to the original low value of the same index indicates aggregation of remaining plantation ages at landscape level. Establishment of low capacity forest biomass‐based power plants and adoption of an integrated regional level planning approach could help in maintaining original age structure characteristics of surrounding forest plantations to a large extent. This might help in sustaining various ecosystem services including biodiversity conservation obtained from forest plantations in a long run.     

Forest transition in Vietnam and its environmental impacts

This study assesses the presence of a forest transition – that is, a shift from net deforestation to net reforestation – in Vietnam during the 1990s, and describes its key attributes relevant for global environmental change issues. Using Fuzzy Kappa and other indicators, we compared forest cover estimates and spatial patterns from global and national land cover maps from the early and late 1990s, and compiled other available statistics for years before and after that period. This showed that a forest transition indeed occurred in Vietnam: the forest cover dropped to 25–31% of the country area in 1991–1993, and then increased to 32–37% in 1999–2001. The reforestation occurred at a higher rate than deforestation in the previous decades, and was due in similar proportions, to natural forest regeneration and to planted forests. The carbon stock in forests followed a similar transition, decreasing to 903 (770–1307) Tg C in 1991–1993, and then increasing to 1374 (1058–1744) Tg C in 2005. However, forest density declined during the same period, with an increasing proportion of young and degraded forests. The effects on habitats measured with landscape pattern indices were contrasted: in several regions, the reforestation decreased forest fragmentation, while in others, clearing of old‐growth forests continued and/or forest fragmentation increased. This shows that a transition in forest area is not sufficient to rehabilitate the different ecosystem functions and services of forests. Other forest transitions exist in Tropical Asia and in Latin America. Knowledge about the causes, pattern and environmental impacts of the forest transition in Vietnam is therefore relevant to understand possible emerging regional trends that would have implications for global environmental change.     

赣南地区土地利用格局及生态系统服务价值的时空演变

江西省的赣南地区是典型的南方山地丘陵区,属于赣江流域重要的生态屏障区,生态保护的意义重大。以赣南为研究区域,基于1990—2015年间的6期遥感影像,利用遥感、地理信息技术和空间统计的方法,计算了该区域土地利用动态度,对不同生态用地所提供的生态系统服务价值进行评估,分析了生态系统服务价值时空差异的驱动因素,并将人均GDP、人口密度和城市化率3个因素与生态系统服务价值进行空间相关性分析。结果表明:(1)1990—2015年间,赣南地区综合土地利用动态度持续上升,各用地类型的综合土地利用动态度从0.06上升到0.13。(2)1990—2015年间赣南地区共减少生态系统服务价值20.42×10~8元,处于下降趋势,其中森林的生态系统服务价值损失最大。研究区调节服务价值最高,其供给服务较低,该地区森林覆盖率高,耕地分散是造成该结果的主要原因。(3)人均GDP、人口密度和城市化率3个因素是生态系统服务价值变化的主要驱动因素且与生态系统服务价值的局部空间相关性高度一致。城市化率越高,生态系统服务价值越低,并形成局部低-高型和高-高型集聚分布。本研究为合理布局和保护我国南方丘陵地区的生态用地,发挥赣南地区的生态屏障作用提供了理论依据和决策支持。     

Comparison of phenology trends by land cover class: a case study in the Great Basin, USA

Direct impacts of human land use and indirect impacts of anthropogenic climate change may alter land cover and associated ecosystem function, affecting ecological goods and services. Considerable work has been done to identify long‐term global trends in vegetation greenness, which is associated with primary productivity, using remote sensing. Trend analysis of satellite observations is subject to error, and ecosystem change can be confused with interannual variability. However, the relative trends of land cover classes may hold clues about differential ecosystem response to environmental forcing. Our aim was to identify phenological variability and 10‐year trends for the major land cover classes in the Great Basin. This case study involved two steps: a regional, phenology‐based land cover classification and an identification of phenological variability and 10‐year trends stratified by land cover class. The analysis used a 10‐year time series of Advanced Very High Resolution Radiometer satellite data to assess regional scale land cover variability and identify change. The phenology‐based regional classification was more detailed and accurate than national or global products. Phenological variability over the 10‐year period was high, with substantial shifts in timing of start of season of up to 9 weeks. The mean long‐term trends of montane land cover classes were significantly different from valley land cover classes due to a poor response of montane shrubland and pinyon‐juniper woodland to the early 1990s drought. The differential response during the 1990s suggests that valley ecosystems may be more resilient and montane ecosystems more susceptible to prolonged drought. This type of regional‐scale land cover analysis is necessary to characterize current patterns of land cover phenology, distinguish between anthropogenically driven land cover change and interannual variability, and identify ecosystems potentially susceptible to regional and global change.     

Spillover of Insects from Rain Forest into Adjacent Oil Palm Plantations

Conversion of natural forest to oil palm plantations is a major threat to biodiversity in Southeast Asia. The retention of natural forest habitats within plantations has been proposed as a method to reduce biodiversity losses in agricultural areas, and we examined whether forest areas resulted in spillover of species into adjacent oil palm plantations. We sampled ants and butterflies along two 2‐km transects across an ecotone from plantation into adjacent forest in Sabah, Malaysian Borneo. Species richness of both taxa was reduced in plantations, but to a greater extent in butterflies (54% reduction) than in ants (25% reduction). Butterfly diversity increased in plantations with increasing proximity to forest primarily due to spillover of ‘vagrant’ forest species (whose larval host plants do not occur in plantations), although richness of species that could potentially breed in plantations also increased near to forest. By contrast, ants showed no spillover effects and were less sensitive to land‐use changes, with much higher levels of similarity in species assemblages across habitats than for butterflies. Our results for butterflies suggest that despite the negative impacts of plantations on diversity, proximity to forest could improve diversity in adjacent plantations for some taxa. Spillover of forest species implies that retaining forest areas within plantations may be important for facilitating dispersal of some species through the landscape.     

基于土地利用变化和生态系统服务的海岸带生态安全综合评价——以胶州湾为例

以土地利用为主的陆域开发活动能改变近海环境质量,并影响和改变原有海岸带生态系统服务功能的供给模式,对海岸带生态安全产生一定的负面影响.目前在海岸带生态系统研究领域较多采用陆地生态系统研究模式,未能真正体现海岸带作为海陆结合的独立的环境体系的特点,并缺乏对陆域活动驱动与生态系统服务功能响应和生态安全实现之间复杂关系的科学解释.本研究基于海岸带生态系统服务的空间异质性和流动性特点,以“土地利用变化(LUCC)-生态系统服务(ES)-生态系统安全”为研究主线,构建海岸带生态安全评价模型,探讨以土地覆被变化为主的陆域活动对海岸带生态系统服务功能和区域生态安全的影响机理及其时空变异规律.从模型的评价结果上看,作为生态安全系统中主要压力表征的胶州湾陆域土地利用变化,与相应海域内的生态系统服务状况和生态安全状态呈现出一定的相关性和趋势性.随着环胶州湾地区城市化进程中大量用地流转为城乡建设用地,胶州湾中相应海域的生态系统服务状态下降,进而带来该海域生态安全状态恶化.本文所提出的基于压力-状态-响应(PSR)框架的海陆结合的生态安全评价模型,以探讨陆域活动对海岸带生态系统服务功能和区域生态安全的影响及其时空变异规律为目的,可以克服目前研究中只关注陆域部分而忽视陆域活动与海域部分之间的联系和相互影响的缺陷,对海岸带生态安全评价研究具有一定的改进作用.     

Regional ecosystem health response to rural land use change: A case study in Lijiang City,China

Quantitative analysis of the response of ecosystem health to rural land use change is required to comprehend the human-nature coupling mechanism and to explore the process of global environmental change, which can interpret the ecological effects of regional land use and land cover change comprehensively. However, the existing regional ecosystem health assessment largely ignored either the internal connection of ecosystem health to land use patterns or the internal representation of ecosystem services to ecosystem health. Using Lijiang City of China as a study area, the average normalized difference vegetation index (NDVI), landscape metrics, and ecosystem elasticity coefficient based on different land use types were used as quantitative indicators. Then the coefficient of spatial neighboring effect was introduced to characterize the adjacency effect on ecosystem services, and to generate the index of integrated ecosystem health. The results showed the change of land use was close to 30% at county level from 1986 to 2006, and forest land was the primary land use type. With respect to the declining physical health of ecosystems in all the four counties, the integrated health experienced a slight increase in Lijiang County. The vast majority of towns’ ecosystem physical health and integrated health declined, while more than 70% of towns did not change distinctly. Ecosystem physical health had distinct influence on the integrated ecosystem health, and ecosystem vitality was the main factor affecting the condition of physical health. Emphasized in the interconnection of pattern and process, this study provided an ecosystem health approach to assessing the integrated ecological effects of regional land use change.     

Woody vegetation dynamics in the tropical and subtropical Andes from 2001 to 2014: Satellite image interpretation and expert validation

The interactions between climate and land‐use change are dictating the distribution of flora and fauna and reshuffling biotic community composition around the world. Tropical mountains are particularly sensitive because they often have a high human population density, a long history of agriculture, range‐restricted species, and high‐beta diversity due to a steep elevation gradient. Here we evaluated the change in distribution of woody vegetation in the tropical Andes of South America for the period 2001–2014. For the analyses we created annual land‐cover/land‐use maps using MODIS satellite data at 250 m pixel resolution, calculated the cover of woody vegetation (trees and shrubs) in 9,274 hexagons of 115.47 km², and then determined if there was a statistically significant (p < 0.05) 14 year linear trend (positive—forest gain, negative—forest loss) within each hexagon. Of the 1,308 hexagons with significant trends, 36.6% (n = 479) lost forests and 63.4% (n = 829) gained forests. We estimated an overall net gain of ~500,000 ha in woody vegetation. Forest loss dominated the 1,000–1,499 m elevation zone and forest gain dominated above 1,500 m. The most important transitions were forest loss at lower elevations for pastures and croplands, forest gain in abandoned pastures and cropland in mid‐elevation areas, and shrub encroachment into highland grasslands. Expert validation confirmed the observed trends, but some areas of apparent forest gain were associated with new shade coffee, pine, or eucalypt plantations. In addition, after controlling for elevation and country, forest gain was associated with a decline in the rural population. Although we document an overall gain in forest cover, the recent reversal of forest gains in Colombia demonstrates that these coupled natural‐human systems are highly dynamic and there is an urgent need of a regional real‐time land‐use, biodiversity, and ecosystem services monitoring network.     

Forest Transition in Xishuangbanna,Yunnan

Forest transition is a process of overall forest cover from net loss to net gain over time. Forest transition especially the process after turning point from deforestation to reforestation has inspired lots of researches for its potential to improve environmental services. China has undergone forest transition since the 1980s. However, in tropical China, deforestation was still existed, while the overall forest cover increased greatly. To investigate this issue, we conducted this research by classifying overall forest into natural forest and plantation in Xishuangbanna, which has undergone forest transition and deforestation and overall forest cover increasing. We found that natural forest continues decreasing while overall forest cover increasing and plantation expansion in forest transition. The forest transition in Xishuangbanna was found to be a tree cover transition, which was mainly contributed by large plantation expansion. In Xishuangbanna, deforestation is still undergoing after its overall forest cover transition occurred in 1988. The general overall forest definition used by forest transition will not be able to recognize deforestation when natural forests are displaced by plantations because the overall forest cover remains unchanged or even increasing. We therefore recommended to classify forest types in forest transition researches.     

不同土地覆被格局情景下多种生态系统服务的响应与权衡——以雅砻江二滩水利枢纽为例

在二滩水库集水区,按照当地生态政策发展以坡度为指标构建了10种未来土地覆被格局情景,研究生态系统减轻水库泥沙淤积、减轻水库面源污染、产水发电服务及价值对未来覆被格局的响应程度,并兼顾相关产业收益的变化,权衡各种情景格局的服务效益,优选利益相关方福祉提升幅度最大的情景格局。结果表明:1)现有土地覆被格局对减轻水库泥沙淤积功效的发挥不合理,而以退耕还林政策指导区域土地覆被格局变化,对集水区减轻河道和水库泥沙淤积具有较好功效。10种情景下,保沙价值的高低关系同入库泥沙量正好相反,遵循"随地表林地和草地面积比例的增加,保沙价值增加"的规律。随产沙总量的增加,高产沙强度像元呈现从水库周边逐渐向中上游蔓延的趋势。2)退耕还林政策单纯以坡度作为指标,指导土地覆被的转化,对集水区减轻水环境磷素非点源污染功效较差。除了全为未利用地覆被的情景10,余下9类情景模拟的入库磷素量及过滤磷素经济价值的高低关系完全一致,呈农田草地林地的规律。随入库磷素总量的增加,高强度磷素输出像元从雅砻江流域源区和大河湾区,逐渐蔓延扩散至集水区整个水网。3)随着集水区地表林地覆盖面积比例的减少,集水区生态系统总发电净利润值增加,且高净利润像元呈现从冕宁和喜德县的东部逐渐向整个集水区东南部乃至整个下游蔓延的趋势。4)从减轻对环境的负效应以及提升利益相关方福祉的角度,以坡度6°上下划分林地和耕地的情景5和以坡度15°和6°为阈值划分林草农的情景3为除极端的情景外,综合指标提升最高的两种情景。