洪湖湖区土地利用／土地覆盖时空格局研究

利用1987,1993和1998年的遥感影像资料,研究了江汉平原洪湖湖区土地利用／土地覆盖的时空变化,土地覆盖类型分为水体,湖滩植被,洪泛地,农田,裸地和居民地6类,运用GIS（Arc/Info)软件,将不同时期的土地利用／土地覆盖的格局进行了清晰的空间表达;通过叠加3个不同时段的影像分类图,计算出各种土地利用／土地覆盖类型转变成其他类型的比例,在1987－1993年期间,水体和洪泛地的面积分别增加了15．54％和9．62％,而1993－1998年期间这两种类型的变化较小,分别为0．58％和3．19％,农田面积从1987年的577．62km^2减少到1998年的188．58km^2,减少约2／3,在研究期间,裸地面积没有明显变化,湖潍植被的面积在1987－1993年期间降低18．60%,而在1993－1998年期间增加8．47％,土地利用／土地覆盖状况的变化与湖区退田还湖及降雨状况的年际变化有关。     

Change and Continuity in a Pastoralist Community in the High Peruvian Andes

Pastoralists of the high Andes Mountains raise mixed herds of camelids and sheep. This study evaluates the land use of herdsmen who are confronted by both socioeconomic and climate changes in Huancavelica, central Peru. Land use/ land cover change (LULCC) was measured through satellite imagery, and pastoralists’ capacity to adapt to socioenvironmental changes was evaluated through interviews and archival research. The most dynamic LULCCs between 1990 and 2000 were large increases in wetlands and a loss of permanent ice. We conclude that the people’s responses to these changes will depend on availability of institutions to manage pastures, other household resources, and perceptions of these biophysical changes. Socioenvironmental change is not new in the study area, but current shifts will likely force this community to alter its rules of access to pastures, its economic rationales in regards to commodities produced, and the degree of dependence on seasonal wage labor. In this scenario, households with a greater amount of livestock will fare better in terms of assets and capital that will allow them to benefit from the increasing presence of a market economy in a landscape undergoing climate change.

Effectiveness of natural protected areas to prevent land use and land cover change in Mexico

This study evaluated the extent to which natural protected areas (NPAs) in Mexico have been effective for preventing land use/land cover change, considered as a major cause of other degradation processes. We developed an effectiveness index including NPA percentage of transformed areas (agriculture, induced vegetation, forestry plantations, and human settlements) in 2002, the rate and absolute extent of change in these areas (1993–2002), the comparison between rates of change observed inside the NPA and in an equivalent surrounding area, and between the NPA and the state(s) in which it is located. We chose 69 terrestrial federal NPAs, decreed before 1997, that were larger than 1,000 ha, not urban/reforested with non-native vegetation, not islands and not coastal strips, and estimated the extent of transformed areas using 1993 and 2002 land use/land cover maps. Over 54% of NPAs were effective, and were heterogeneously distributed by management categories: 65% of Biosphere Reserves, 53% of Flora and Fauna Protection Areas, and 45% of National Parks. 23% of NPAs were regarded as weakly effective, and the remaining 23% as non-effective. We recognize the importance of NPAs as a relevant conservation instrument, as half of NPAs analyzed (particularly biosphere reserves) prevented natural vegetation loss compared with their geographic context. Our results suggest that conservation based on NPAs in Mexico still faces significant challenges. Our approach can be expanded for evaluating the effectiveness of NPA in other regions, as land use/land cover maps are now available almost worldwide.     

海南岛海莲红树林的钙镁累积和循环

本文是海南东寨港红树林研究的一部分,主要讨论55年生海莲林的Ca、Mg元素的累积和生物循环。试验结果表明,在海莲群落现存量中,含有Ca、Mg总量分别为3258.1和597.9kg·ha~(-1),其中地上部分别为1891.9和247.1kg·ha~(-1),地下部分别为1366.2和350.8kg·ha~(-1)。该群落的Ca、Mg元素的生物循环中,年吸收量分别为382.0和100.4kg·ha~(-1),存留量131.3和20kg·ha~(-1),归还量为250.7和80.4kg·ha~(-1)。Ca的周转期为13年,较Mg8年为慢。     

Extent and spatial patterns of grass bald land cover change (1948–2000), Oregon Coast Range,USA

Globally, temperate grasslands and meadows have sharply declined in spatial extent. Loss and fragmentation of grasslands and meadows may impact biodiversity, carbon storage, energy balance, and climate change. In the Pacific Northwest region of North America, grasslands and meadows have declined in extent over the past century. Largely undocumented in this regional decline are the grass balds of the Oregon Coast Range, isolated grasslands in a landscape dominated by coniferous forests. This study was conducted to quantify the spatial extent and patterns of grass bald change. Five balds in the Oregon Coast Range were evaluated using historical aerial photographs and recent digital orthophoto quadrangles (DOQ). Over the time period of study (1948/1953 to 1994/2000), bald area declined by 66%, primarily from forest encroachment. The number and average size of bald vegetation patches declined, while edge density increased. Tree encroachment into balds was inversely related to distance from nearest potential parent trees. Spatial patterns of bald loss may result from a forest to bald gradient of unfavorable environmental conditions for tree establishment and/or seed dispersal limitation. Species dependent on balds may be at risk from loss of bald area and increased fragmentation, although metrics of habitat fragmentation may not reflect species-specific habitat requirements. Tree encroachment patterns and increased bald edge densities suggest increasing rates of bald loss in the future. The remote sensing nature of this study cannot determine the fundamental causes of bald decline, although prior research suggests climate change, cessation of native burning, successional changes in response to prior wildfires, and cessation of livestock grazing all may have potential influence.     

近十年卧龙地区流域土地覆盖/利用变化分区对比研究

土地利用与生态系统保护之间的矛盾直接影响着卧龙保护区及周边地区的土地覆盖变化,为考察人类活动对卧龙地区土地覆盖/利用变化的影响,对近十年卧龙两流域土地覆盖/变化进行了分区对比研究,结果表明,卧龙地区两流域及其分区土地覆盖/利用变化趋势有所不同。主要差异表现在:①寿溪、渔子溪流域虽然林地面积均有所增加,但林地破碎化程度远远高于渔子溪。灌丛在寿溪流域的比重减少而在渔子溪流域增加。②分区比较的结果为,林地的增加主要发生在寿溪保护区的外部和渔子溪保护区内部,草地的减少主要发生在两流域保护区内部。③两流域总体土地利用变化率随河谷缓冲带的扩张变化趋势相反。④两流域各类型转移概率不同导致未来转移方向的不同。Markov模型预测,未来十年渔子溪流域林地、灌丛的增加和草地的减少仍较明显,寿溪流域林地面积继续增加,农田、灌丛继续减少。     

Biodiversity impact analysis in northwest Yunnan, southwest China

This paper reports the main findings of a study on the factors threatening biodiversity in northwest Yunnan, a global biodiversity hotspot in China and home to over five million people. The research was based on eight site-level case studies. The main driving forces of biodiversity loss are livelihood activities, including agricultural production, livestock grazing and the collection of fuel wood, construction timber and NTFPs. Behind these specific drivers are underlying factors including changes in demography, market conditions, resource tenure policies and development policies and projects. Some change in land cover has been due to specific trigger events, the most significant of which reflect national policy changes. At the site level, a range of biophysical and socio-cultural factors influence the specific outcomes that any particular factor may have. The paper suggests some specific redressive measures and general implications for research and policy.     

An Assessment of Trends in the Extent of Swidden in Southeast Asia

Swidden systems consisting of temporarily cultivated land and associated fallows often do not appear on land use maps or in statistical records. This is partly due to the fact that swidden is a diverse and dynamic land use system that is difficult to map and partly because of the practice of grouping land covers associated with swidden systems into land use or land cover categories that are not self-evidently linked to swiddening. Additionally, in many parts of Southeast Asia swidden systems have changed or are in the process of changing into other land use systems. This paper assesses the extent of swidden on the basis of regional and national sources for nine countries, and determines the pattern of changes of swidden on the basis of 151 cases culled from 67 articles. Findings include (1) a majority of the cases document swidden being replaced by other forms of agriculture or by other livelihood systems; (2) in cases where swiddening is still practiced, fallow lengths are usually, but not always, shorter; and (3) shortened fallow length does not necessarily indicate a trend away from swidden since it is observed that short fallow swidden is sometimes maintained along with other more intensive farming practices and not completely abandoned. The paper concludes that there is a surprising lack of conclusive data on the extent of swidden in Southeast Asia. In order to remedy this, methods are reviewed that may lead to more precise future assessments.     

洪湖围垦的生态经济损益调查分析

围湖造田原是人类改造衰老湖泊的生产活动,但到七十年代却成为时髦,耗费巨大劳力和资财,所围之田往往颗粒无收,湖泊资源严重丧失,此时已由积极一面向消极、破坏一面转化,人们尝到大自然抛回来的苦果。笔者以湖北省最大的洪湖遭受强烈围垦为例,粗略分析围湖造田以后的经济损益及其在整个湖区生态学方面的综合反应与效果,敬祈指正。一、分析围湖造田利弊应有生态经济学观点围湖造田是人们作用于自然环境,造就人工环境的生产活动,若遵循自然规律合理进     

气候波动和土地覆盖变化对广东省植被净初级生产力的相对影响

为深入理解人类活动对陆地生态系统的影响,采用CASA(Carnegie-Ames-Stanford Approach)模型估算广东省2000、2005和2010年实际植被净初级生产力(Net primary productivity,NPP),并基于情景模拟法估算气候和土地覆盖类型稳定条件下的植被NPP,对气候波动和土地覆盖变化在植被NPP变化中的相对贡献进行了研究。结果表明:太阳辐射对植被NPP具有显著的正向控制作用,气温与植被NPP表现为显著负相关,降水不是该区域植被生长的限制性因子;各气候因子与植被NPP的相关性具有季节和区域差异性。在气候不变条件下,土地覆盖变化整体上增加了NPP,对NPP变化的相对贡献与城市扩张格局相类似,不同生态区存在差异性,以珠三角区的贡献最大。总之,气候波动对NPP变化的相对贡献较为复杂,取决于气候因子的波动特征以及与NPP的相关性;其它因子(城市热岛、农耕活动和园林管理等)对NPP变化的相对贡献存在很多不确定性,整体上增加了NPP。     

<Emphasis Type="Italic">Daphnia galeata</Emphasis> in the deep hypolimnion: spatial differentiation of a “typical epilimnetic” species

One of the most serious threats to tropical mangrove ecosystems caused by shrimp farming activities is the poor management of pond waste materials. We hypothesise that mangroves can tolerate chemical residues discharged from shrimp farms and can be used as biofilters, but the capability of mangroves to cope with solid sediments dredged from shrimp ponds is limited. Our study in Pak Phanang, Thailand, confirmed that the excess sediments discharged from nearby shrimp ponds reduced mangrove growth rates and increased mortality rates. A series of transformed multi-temporal satellite images was used in combination with the field data to support this claim. In addition, a comparison between four dominant mangrove species revealed that Avicennia marina could tolerate sedimentation rates of >6 cm year⁻¹, while Bruguiera cylindrica tolerated sedimentation rates of 5 cm year⁻¹ (total sediment depth = 25 cm) before dying, while Excoecaria agallocha and Lumnitzera racemosa performed intermediate. This outcome implied that in our situation A. marina and to lesser extent E. agallocha and L. racemosa could be more effective as biofilters than B. cylindrica, as they may survive the sedimentation longer in the disposal areas. Further studies on the impact of sedimentation and chemical pollution of shrimp farm wastes on mangrove mortality and growth are required.     

新疆焉耆盆地人类活动与气候变化的效应机制

通过对新疆焉耆盆地及其周边近40a(1973—2014)的气候变化趋势检测、LUCC和生物量估算,探讨气候变化和人类活动的生态效应机制,研究区域陆地生态系统演变及其归因。分析结果表明:(1)焉耆盆地山区和平原区降水变化都有明显的突变点,并呈现增加趋势,蒸发量在山区减少,在平原区波动性减少趋势;(2)LUCC分析表明,山区裸地面积减少5.40%,冰川面积减少3.36%,高地植被面积增加8.76%;同时平原区天然绿洲面积增加1.96%,沙漠面积减少1.62%,水域面积减少1.30%,人工绿洲面积增加15.41%,湿地面积增加1.27%;(3)山区陆地生态系统对区域气候变化非常敏感,其中降水变化是决定山区地表植被生存状态和分布的重要因素;(4)人类活动的推动作用和有益气候变化的支撑是绿洲平原区生态系统好转的原因,其中人口急剧增加和社会经济快速发展,导致绿洲平原区生态系统结构及其时空分布的主要因素。焉耆盆地及其周围区域陆地生态系统的演变对气候变化和人类活动有明显的时空尺度效应,其反应程度各不相同。