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1.
The maleo (Macrocephalon maleo) is an endemic bird of Sulawesi that lays eggs in communal nesting grounds incubated by solar or geothermal sources. In recent years, maleo nesting grounds have become increasingly vulnerable to threats associated with the growing human population of the island. Consequently, the maleo has become one of the most imperiled bird species in Indonesia and is classified as Endangered on the IUCN Red List. We report on the 2004 status of maleo nesting grounds in North Sulawesi focusing on the Bogani Landscape, the region in and around Bogani Nani Wartabone National Park, where the nesting grounds are concentrated. We compare our results to those of a similar study in 1990-1991, examining changes in nesting ground status in relation to habitat and land use factors such as protection status, geographic position (coastal or inland), and distance to forest, human settlements, and roads. Nesting grounds were more likely to be abandoned if they were: (a) in coastal areas; (b) near settlements and roads; and (c) not in protected areas. Binary logistic regression identified connectivity between nesting grounds and forest in 1991 as the best predictor of whether or not sites were abandoned by maleo over the next 12 years; a loss of local continuity between nesting grounds and forest is associated with a sixfold increase in the probability of abandonment. Access to forest was itself highly correlated with other variables examined, and thus represented a composite index of threats to maleo. The application of this model to the 2004 data identified six active nesting grounds that are at high risk of abandonment in the near future, seven at intermediate risk, and five at low risk. These results offer conservationists priorities for future maleo conservation. 相似文献
2.
H. Alphan 《Land Degradation \u0026amp; Development》2012,23(3):278-292
This study classified land cover conversions by using quantitative change detection methods in the eastern Mediterranean coastal wetlands of Turkey. Three Landsat TM scenes acquired in 1984, 1998 and 2007 were analysed using image pairs of consecutive dates. The amounts of change were calculated for the periods from 1984 to 1998 and from 1998 to 2007, using binary change masks and supervised image classifications, in which eleven a priori defined land cover classes were used. Change areas accounted for 14.81 and 15.64 per cent of the total area, in the first and second periods, respectively. Conversions from/to sand dunes, mud flats and afforestation were by far the most extensive changes. Sand dunes and mud flats decreased, while afforestation and agriculture areas increased in the 23‐year period between 1984 and 2007. Five types of qualitative change were identified on the basis of land cover transformations within and between natural and anthropogenic systems. Type I changes, which indicated conversions from (semi)natural to anthropogenic systems, took place as agricultural expansion over coastal sand dunes, while Type II changes mostly occurred within agricultural systems. Type III changes included changes in human uses, leading to conversions from one anthropogenic system to another. Conversions between semi(natural) systems such as salt marshes and mud‐flats were typical Type IV changes. Type V changes were mainly due to conversions from agriculture to wetland categories or other semi(natural) cover types. Implications of these changes were discussed for management of coastal environmental resources. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
3.
Steffen Oppel André F. Raine John J. Borg Helen Raine Elsa Bonnaud Karen Bourgeois André R. Breton 《Biological conservation》2011,(9):2255-2263
Many seabird species are experiencing population declines, with key factors being high adult mortality caused by fishery by-catch and predation by introduced predators on nesting islands. In the Mediterranean, both of these pressures are intensive and widespread. We studied the adult survival of an endemic Mediterranean seabird, the Yelkouan shearwater (Puffinus yelkouan), between 1969–1994 and 2007–2010 in Malta and between 2004–2010 in France using mark–recapture methods. Mean annual survival probabilities for breeding adults were below 0.9 for all colonies and periods. Between 1969–1994, annual survival for adults of unknown breeding status was on average 0.74 (95% confidence interval: 0.69–0.80) in Malta, possibly as a result of various human disturbances (including illegal shooting), light pollution and fisheries by-catch. Over the period 2004–2010, we found strong support for variation in adult survival probabilities between breeders and non-breeders, and islands with and without introduced predators in France. Survival probabilities for non-breeders (0.95, 0.81–1.0) appeared to be higher than for breeders (0.82, 0.70–0.94), but were imprecise partly due to low recapture probabilities. In Malta, we found evidence for heterogeneity in survival probabilities between two unknown groups (probably breeders and non-breeders), and seasonal variation in survival probability. Birds were more likely to survive the period including the peak breeding season than an equally long period during which they roam widely at sea. Although annual adult survival probability was still low (0.85, 0.58–1.0), colony protection measures appear to have reduced mortality at nesting cliffs. A population model indicated that colonies in France and Malta would currently require continuous immigration of 5–12 pairs per year to maintain stable populations. Our estimates of adult survival probabilities over the past four decades are consistent with overall population declines. Threats to Yelkouan shearwaters require immediate management actions to avoid ongoing population declines in the western Mediterranean. 相似文献
4.
Annual soil losses in southern Italy can exceed 100–150 t ha− 1 year− 1. Where erosion on agricultural land is particularly severe, land use change and afforestation are frequently seen as the most appropriate means of reducing erosion risk. However, the overall effectiveness of afforestation in reducing soil erosion remains uncertain, due to the poor development of the forest cover in some areas, leading to significant areas with sparse tree cover, and the erosional impact of forest harvesting, which commonly involves clearcutting. The study reported here addresses this uncertainty and focuses on two small catchments (W2 and W3) located in Calabria, southern Italy, for which measurements of suspended sediment yield are available. Both the catchments originally supported a rangeland vegetation cover and they were planted with eucalyptus trees in 1968. Currently, only catchment W3 supports a continuous forest cover. In catchment W2 the forest cover is discontinuous and there is a significant area of the catchment (ca. 20%) where the tree cover is sparse and the vegetation cover is dominated by natural grasses. Two additional erosion plots were established within catchment W2 in 1991, in order to explore the effect of the density of the tree cover on soil erosion. Information on the sediment yields from the two catchments and the plots for 10 storm events that occurred during the period December 2005–December 2006 and associated information on the 137Cs and excess 210Pb of the sediment, have been used to investigate the effectiveness of afforestation in reducing sediment mobilisation and net soil loss from the catchments involved. The results demonstrate that the areas of greatest soil loss are associated with the slopes where the tree cover is discontinuous, and that forest harvesting by clearcutting causes significant short-term increases in sediment mobilisation and sediment yield. These findings, which are consistent with previous work undertaken within the same area, emphasize the importance of vegetation cover density in influencing rates of soil loss in the study catchments. The study also provided a useful demonstration of the potential for using measurements of the 137Cs and 210Pbex content of sediment, in combination with more traditional sediment monitoring, to investigate sediment sources and to compare the sediment dynamics of catchments subjected to different land management practices. 相似文献
5.
[目的]分析华东地区土地覆被变化过程对土壤水分的影响,以期能够揭示土地覆被变化对土壤水分的影响机理.[方法]应用MODIS三级土地覆被产品MCD12Q1,采用轨迹分析方法描述20032010年耕地和林地轨迹变化过程;选择基于AMSR-E土壤水分数据的降尺度反演结果作为描述土壤水分变化的数据,研究华东地区土地覆被变化对土壤水分的影响.[结果](1)每种土地覆被类型均有3种轨迹变化形式:研究年限内面积增加的轨迹、面积减少的轨迹、研究年限内未发生面积变化的轨迹;(2)在耕地和林地3种轨迹变化过程中,土壤水分含量均表现出下降的趋势.(3)在林地的3种轨迹变化过程中,土壤水分含量大小顺序为:未发生轨迹变化的林地＞林地面积增加的轨迹＞林地面积减少的轨迹;在耕地的3种轨迹变化过程中,土壤水分含量大小排序为:耕地面积减少的轨迹＞耕地面积增加的轨迹＞未发生轨迹变化的耕地;(4)耕地、林地轨迹变化过程对土壤水分的影响均与时间年限有关,至少需要7 a林地土壤水分含量达到最大值,此时耕地土壤水分含量达到最小值.[结论]作为华东地区主要的土地覆被类型,耕地和林地在2003-2010年的所有变化轨迹过程中,土壤水分均呈现下降趋势,且土壤水分随着育林年限和耕种年限的增长分别增加和减小,并在第7 a分别达到最大和最小. 相似文献
6.
Soil organic matter (SOM) was monitored at five research sites along a climatic transect extending from the Judean Mountains (mean annual rainfall 700 mm; annual mean temperature 17 °C) to the Dead Sea (mean annual rainfall < 100 mm; annual mean temperature 23 °C) in Israel. At four sites, representing four climatic regions, Mediterranean (site GIV), semi-arid (site MAL), mildly arid (site MIS) and arid (site KAL), four to eight soil samples were taken four times a year, in January, March, May and September, from 1992 through 1993 and 1994 and in April and August 2000. In the last 2 months soil samples were also taken from another site (MAB) in the semi-arid area. Comparison between the sites along the climatic transect shows that, except for site MAB, SOM increased significantly in both 0–2 cm and 2–10 cm, from the arid site, through the mildly arid site and the semi-arid site, to the Mediterranean site. Analysis of SOM temporal patterns of the two semi-arid sites (MAL and MAB) shows significant change from the normal SOM pattern in both the regional scale and the soil profile scale in one site (MAB). The a-normal pattern of SOM and the low soil aggregate stability at MAB indicates land degradation and it is attributed to overgrazing. 相似文献
7.
古尔班通古特沙漠人工梭梭林群落生态特征研究 总被引：3，自引：0，他引：3
为探究古尔班通古特沙漠南缘莫索湾地区33年来人工梭梭林群落(依靠天然降水)的生态特征,本文对两种造林技术(积雪-客沙造林和秋灌造林)人工梭梭林地梭梭的长势、草本植物、土壤水分进行了调查和监测。结果表明:(1)积雪-客沙造林和秋灌造林梭梭至今生长良好,目前植株高度和冠幅均大于2 m和2 m~2,当年新生枝条长度均大于20 cm;初始造林梭梭存活率较高,分别为40%和63%;经过自然更新,现有密度均有所提高,人工林形成异龄复层混交林,林下生长有不同优势种的草本植物;土壤含水量均2.00%,能够满足梭梭生长。(2)由于两种造林技术的土地处理方式和初期水分供给量不同,导致两种林地梭梭生长、林下草本植物盖度和多样性以及天然更新梭梭植株数量均有很大差异,整体秋灌造林地的状况优于积雪-客沙造林地。(3)两种造林技术对于当地生态条件均有很好的适应性,虽然积雪-客沙造林密度相对较低,但优于自然植被状况,且造林成本低;秋灌造林密度较大,天然更新植株数量较多,但造林成本高,后期生长较缓慢,需要采取一定的人工措施调整密度。综上可知,积雪-客沙造林和秋灌造林梭梭目前生长均较稳定,后者对该区生态条件适应性更强。 相似文献
8.
为了解青海东部黄土高原寒区退耕还林地人工林的水分生产力水平,2001—2003年对青海省大通县退耕还林的人工林进行了群落蒸散测算、标准地生物量调查和解析木分析,并研究了青杨灌木混交林、白桦紫果云杉混交林、华北落叶松纯林、紫果云杉纯林、白桦纯林等11种林分类型退耕还林人工林的林木水分生产力。结果表明:1)3 000株/hm2左右密度的林分是该区较为适宜的造林密度标准;2)在目前的技术经济水平条件下,2 1003333株/hm2密度的青杨灌木混交林成林、白桦纯林、紫果云杉纯林和白桦紫果云杉混交林水分生产效率居所有林分之首,其水分生产力指标可作为该地区常规造林技术条件下乔木成林的水分生产力标准;3)3000株/hm2左右密度的青杨灌木混交林、白桦紫果云杉混交林、紫果云杉纯林和白桦纯林成林的水分生产潜力基本达到了目前当地林木的最大生产能力。表明上述林分类型的造林模式可作为今后退耕还林工程和林业生态工程建设的发展方向。 相似文献
9.
K.S. Gopi Sundar 《Biological conservation》2011,144(12):3055-3063
In countries with high human populations, using agricultural areas as multifunctional systems to produce food for humans and retain wildlife may be an efficient conservation strategy for many species. Inclusion of natural habitat and species requirements on agricultural landscapes explicitly into planning processes are precluded by lack of information on drivers of species persistence. Climate change is an additional emerging complexity, and adaptation plans for agricultural landscapes are biased towards intensification to secure long-range food production. I examine the conservation potential of an agricultural landscape in two districts of Uttar Pradesh, north India where agricultural intensification and altered rainfall patterns are predicted to occur. I assess stressors affecting breeding success over eight years of two large waterbirds of conservation concern – Sarus Cranes and Black-necked Storks. Both species had high breeding success that improved with total rainfall and more wetlands in breeding territories. Agricultural and township expansions deteriorated territory quality and reduced breeding success. Sarus Crane populations were predicted to decline relatively rapidly if development activities continued to displace breeding pairs. Black-necked Storks appeared resilient over the long-term notwithstanding reduced breeding success in low-rainfall years. Waterbird nesting habitats (wetlands and trees) were retained in Uttar Pradesh as community lands by villages and by state government via legal provisions suggesting the utility of multiple conservation approaches. Incorporating species requirements explicitly, alongside traditional land use practices conducive for habitat conservation, into adaptation planning and conservation policy will be necessary to retain long-term multifunctionality of such agricultural landscapes. 相似文献
10.
11.
Land reclamation using clay and sand materials has been used to increase land area in Singapore. Although some of these areas are put to immediate use, others are ear-marked for future development. in the latter instances, in the interim period, afforestation measures involving some treatment of the land have been adopted. This paper discusses the process of afforestation at two sites with different but poor soils and the performance of the different species of trees planted (which are now 12 years old). the benefits of such an afforestation exercise are convincing and a similar but less expensive process could be adopted to afforest reclaimed lands or rehabilitate derelict lands in developing countries to provide wood for fuel or other purposes. 相似文献
12.
[目的]解决黄河三角洲地区盐碱地改良造林绿化的难点。[方法]分析黄河三角洲目前的盐碱地资源和特点,阐述盐碱地改良与造林绿化现状。在此基础上,依据前人的技术和研究成果,结合作者多年来盐碱地生态改良的研究与实践。[结果]提出了适宜黄河三角洲盐碱地造林绿化的关键技术:(1)利用传统方法造林绿化改良盐碱地;(2)重视新技术和新成果的应用。[结论]利用盐碱地造林绿化关键技术,实现黄河三角形洲滨海盐碱地改良是切实可行的。 相似文献
13.
GIS-based assessment of land suitability for optimal allocation in the Qinling Mountains, China 总被引：14，自引：0，他引：14
A GIS-based method was used to assess land suitability in the Qinling Mountains, Shaanxi Province of China through simultaneous consideration of physical features and current land use. Through interpretation of Landsat TM images and extensive field visits the area was modeled into 40 land types in five altitudinal zones （valleys and gullies, hillsides and terraces, foothills, mid-mountain, and sub-alpine mountain）. Then, a suitability score was assigned to five physical factors （climate, hydrology, topography, soil, and vegetation）. Next, their integrated overall suitability value scores were compared with the observed land cover to determine whether it should be reallocated a new use. Results showed that the five suitability classes of agriculture, forest, grassland, farmland-woodland, and scrub-pasture had altitudinal stratification and a total of 1 151 km^2 （8.89%） of lands on the northern slopes of the Qinling Mountains had to be reallocated. To achieve this reallocation, 657 km^2 of arable land should be reduced, and forest, grassland and scrub-pasture increased by 615 km^2, 131 km^2 and 405 km^2, respectively. Implementation of these recommended land reallocations should help achieve suitable use of land resources and prevent land degradation. 相似文献
14.
Sebastian Wolf Werner EugsterCatherine Potvin Nina Buchmann 《Agricultural and Forest Meteorology》2011,151(8):1139-1151
Pasture and afforestation are land-use types of major importance in the tropics, yet, most flux tower studies have been conducted in mature tropical forests. As deforestation in the tropics is expected to continue, it is critical to improve our understanding of alternative land-use types, and the impact of interactions between land use and climate on ecosystem carbon dynamics. Thus, we measured net ecosystem CO2 fluxes of a pasture and an adjacent tropical afforestation (native tree species plantation) in Sardinilla, Panama from 2007 to 2009. The objectives of our paired site study were: (1) to assess seasonal and inter-annual variations in net ecosystem CO2 exchange (NEE) of pasture and afforestation, (2) to identify the environmental controls of net ecosystem CO2 fluxes, and (3) to constrain eddy covariance derived total ecosystem respiration (TER) with chamber-based soil respiration (RSoil) measurements. We observed distinct seasonal variations in NEE that were more pronounced in the pasture compared to the afforestation, reflecting changes in plant and microbial activities. The land conversion from pasture to afforestation increased the potential for carbon uptake by trees vs. grasses throughout most of the year. RSoil contributed about 50% to TER, with only small differences between ecosystems or seasons. Radiation and soil moisture were the main environmental controls of CO2 fluxes while temperature had no effect on NEE. The pasture ecosystem was more strongly affected by soil water limitations during the dry season, probably due to the shallower root system of grasses compared to trees. Thus, it seems likely that predicted increases in precipitation variability will impact seasonal variations of CO2 fluxes in Central Panama, in particular of pasture ecosystems. 相似文献
15.
Major declines in the abundance of vultures and other scavenging raptors in and around the Masai Mara ecosystem, Kenya 总被引：1，自引：0，他引：1
Munir Z. Virani Corinne Kendall Peter Njoroge Simon Thomsett 《Biological conservation》2011,(2):746-752
Vulture population declines have been noted in West and Southern Africa, but have not been assessed in East Africa. Roadside transects conducted in 1976 and 1988 were compared with surveys done from 2003–2005 in and around Masai Mara National Reserve, Kenya. Staggering declines in abundance were found for seven of eight scavenging raptors surveyed. No Egyptian vultures were seen during recent transects. We compared trends between the ungulate migration and non-migration season among three land use types (reserve, buffer, and grazed) and among the species surveyed to establish the causes of declines in scavenging raptors. Large declines during the ungulate migratory period suggest that most scavenging raptor species are declining well beyond the area of study. For all species, except Hooded vultures, substantial declines outside of the reserve indicate an important role of land use change in causing observed declines. In addition, significant declines of populations of Gyps species in the reserve itself, especially during the migration season, provide evidence that human activities occurring in other parts of the species’ range such as poisoning of carcasses may be causing their decline. Declines found in this study suggest that at a minimum African white-backed, Rüppell’s, and Hooded vultures should be relisted as Vulnerable. Management actions that limit land use change around the reserve combined with a countrywide ban on carbamate pesticides will be important for conserving keystone members of the scavenging guild. Future research should further examine possible causes of these declines and quantify the effect of reduced scavenging raptor abundance on scavenging efficiency. 相似文献
16.
[目的]为满足乌兰布和沙漠绿洲防护林体系构建对优良造林树种选择的要求,对多个品种速生杨在乌兰布和沙区绿洲的适应性进行评价。[方法]以北抗、08、中林等系列的20个引进速生杨品种为研究对象,当前主要造林树种新疆杨为参照,运用系统聚类分析和多因素模糊综合评判方法对20种速生杨在乌兰布和沙漠绿洲地区生长初期适应性进行综合评价。[结果]08-01,创新、中林2005,北抗16-22,08-02,08-03,中林315,08-07,天黑、京2等10个品种在速生性、成活状况、抗病虫害能力方面均明显优于新疆杨;京6,北抗16-27,Simplot,08-09,08-08,08-14等6个品种各项评价指标与新疆杨接近;辽宁杨(鲁×山)、北抗16-8,08-04,DN-34等4个树种综合评价适应性低于新疆杨。[结论]08-01等10个品种能够在乌兰布和沙漠绿洲地区良好生长,可以作为该区造林和植物资源收集储备的备选树种。京6等6个品种综合评价适应性中等,辽宁杨(鲁×山)等4个品种适应性较差,无法在该区正常生长。 相似文献
17.
试验表明,在干旱的黄土丘陵区采用覆盖造林技术,覆盖物选用普通农用塑料薄膜和草类,覆盖塑料薄膜与对照相比,成活率提高幅度分别为2％～17％和17.1％～32％;覆草提高成活率的幅度低于覆膜。试验结果还表明,覆盖不仅能显著促进当年苗木的生长,而且也能促进幼林的生长,其原因主要是提高了林地的土壤水分。 相似文献
18.
Luis V. García Cristina Ramo Cristina Aponte Adela Moreno María T. Domínguez Lorena Gómez-Aparicio Ramón Redondo Teodoro Marañón 《Biological conservation》2011,(2):764-771
Conservation management conflicts frequently arise when an overpopulation of a protected organism has negative effects on other valuable elements in the same ecosystem. We studied the interactions between a colony of protected tree-nesting wading birds and a remnant population of centenarian cork oaks that was part of the formerly dominant forests in the Doñana Biological Reserve (SW Spain). A significant increase in the tree mortality rates has been recorded in areas that are yearly influenced by the bird colony.We analysed a cohort of surviving trees using a gradient of nesting bird influence. Tree-nesting history, bird isotopic signature (δ15N), tree health-related parameters (defoliation, δ13C and leaf surface coverage by faeces) and several soil variables were evaluated. Bird influence was related to increased soil salinity. This increase correlated to increased water-use efficiency for the leaves and to crown defoliation, suggesting that the heavily occupied trees are under higher stress and in poorer health condition than the unoccupied ones. We tested structural equations models (SEM) that were based on hypothesised bird effects on the health of the trees. Soil-mediated effects of the nesting birds best explained the symptoms of the declining health of the trees, whereas the percent of leaves’ surface that was covered by faeces did not improve the fitted SEM model.For the reserve’s managers, a challenging trade-off exists between preserving the relict trees, which have a high genetic diversity and a key ecological role in these savannah-like ecosystems, and maintaining the current nesting area for these protected, but expanding, wading birds. 相似文献
19.
Bedrock surfaces in the Ouachita Mountains, Arkansas, exposed by spillway construction and which had not previously been subjected to surface weathering environments, developed 15–20 cm thick soil covers in less than three decades. All open bedrock joints showed evidence of weathering and biological activity. Rock surfaces and fragments also showed evidence of significant weathering alteration. The results suggest a soil production function whereby weathering and increases in thickness are initially rapid. The rapid initial rate (5 to 10 mm year− 1) is facilitated by a weathering-favorable regional climate, local topography favoring moisture and sediment accumulation, and aggressive vegetation colonization. The ages of the trees on the bedrock benches suggests that a short period (< 10 years) of pedogenic site preparation is necessary before trees can become established. Initial chemical weathering within newly-exposed rock fractures in resistant sandstone strata and chemical weathering of weak shale layers, coupled with accumulation of organic and mineral debris in fractures and microtopographic depressions facilitates plant establishment, which accelerates local weathering rates. 相似文献
20.
盐池县沙漠化土地动态变化影响因素分析 总被引：3，自引：0，他引：3
通过分析宁夏盐池县土地沙漠化的资料和5个时期的陆地卫星遥感影像,研究了1961—2005年间该县的土地沙漠化动态变化规律,探讨了影响土地沙漠化动态变化的因素。研究表明:1983—1989年是盐池县土地沙漠化趋势急剧扩大的阶段;2001—2005年,除固定沙漠化土地面积在小幅增加外,流动、半固定和总的沙漠化土地面积均在减少。影响土地沙漠化动态变化的因素包括降水量、蒸发量等,但起决定性作用的是退耕还林还草、草地禁牧、禁止乱砍乱挖和植树造林等措施。 相似文献