63 resultados para reserves

em Chinese Academy of Sciences Institutional Repositories Grid Portal


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Elevational and latitudinal patterns of species richness for birds and mammals were compared with human population density in relation to nature reserve designation in two areas of Yunnan Province, China. Results suggest that species richness is not the same for the two areas. In Gaoligongshan Region, species richness is inversely correlated with elevation and altitude, while reserve designation is positively correlated with elevation and latitude. In Jingdong County, reserve designations are positively correlated with elevation, but species richness shows no clear trends. In general, the present situation is strongly influenced by human activities. It appears that reserve designation is mismatched with species richness in Gaoligongshan Region, while there is a better fit between the two in Jingdong County. In both areas, however, it appeared that reserves were located primarily in order to reduce conflict with humans rather than to maximize conservation of biodiversity, probably because humans were responsible for forest-especially primary forest-destruction and degradation in the low-lying areas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Ministry of Science and Technology of China [2008BAK47B02, 2008BAC44B04, 2008BAK50B06, 2008BAC43B01, 2006BAC08B06]

Relevância:

10.00% 10.00%

Publicador:

Resumo:

制作含水率与采出程度关系理论曲线常采用相渗曲线法和流管法两种方法.在采用相渗曲线法制作理论曲线时,采用统计回归分析相对渗透率与含水率的关系,导致在低含水饱和度时期含水率偏高,在高含水饱和度时期含水率偏低的问题,解决的方法是直接使用实验数据点计算.将体积波及系数取常数往往会得出"中低含水期开发效果较差,高含水期开发效果较好"的通用结论,解决的方法是分析体积波及系数与井网系统、流度比、渗透率变异系数的关系,建立统计关系式.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Layered steam injection, widely used in Liaohe Oilfield at Present, is an effective recovery technique to heavy oil reserves. Which makes the steam front-peak push forward uniformly, the amount of steam injection be assigned rationally, and the effect of injection steam be obtained as expected. To maintain a fixed ratio of layered steam injection and solve the problem of nonadjustable hole diameter with the change of layer pressure in the existing injectors, a new method is proposed in this paper to design layered steam injectors based on the dynamic balance theory. According to gas-liquid two-phase flow theory and beat transfer theory, the energy equation and the heat conduction equation in boreholes are developed. By analyzing the energy equilibrium of water-steam passing through the injector hole, we find an expression to describe the relation between the cross-sectional area of injector hole and the layer pressure. With this expression, we provide a new set of calculation methods and write the corresponding computer program to design and calculate the main parameters of a steam injector. The actual measurement data show that the theoretically calculated results are accurate, the software runs reliably, and they provide the design of self-adjustable layered steam injectors with the theoretical foundation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Layered steam injection, widely used in Liaohe Oilfield at present, is an effective recovery technique to heavy oil reserves. Which makes the steam front-peak push forward uniformly, the amount of steam injection be assigned rationally, and the effect of injection steam be obtained as expected. To maintain a fixed ratio of layered steam injection and solve the problem of nonadjustable hole diameter with the change of layer pressure in the existing injectors, a new method is proposed in this paper to design layered steam injectors based on the dynamic balance theory According to gas-liquid two-phase flow theory and heat transfer theory, the energy equation and the heat conduction equation in boreholes are developed. By analyzing the energy equilibrium of water-steam passing through the injector hole, we find an expression to describe the relation between the cross-sectional area of injector hole and the layer pressure. With this expression, we provide a new set of calculation methods and write the corresponding computer program to design and calculate the main parameters of a steam injector. The actual measurement data show that the theoretically calculated results are accurate, the software runs reliably, and they provide the design of self-adjustable layered steam injectors with the theoretical foundation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

草地在世界各种不同的气候带和土壤类型区均有分布,约占陆地面积的24%。尽管二十世纪中叶以来,人类通过各种措施,使氮素由大气圈进入生物圈的量已经翻了一翻,但是,草地生态系统由于没有得到足够的氮素补充,其生产力至少是季节性地受到氮素的制约。我国草原生态系统的退化与氮素匮乏已经引起了广泛重视。尽管一些研究者的工作已经涉及到氮素循环的一些方面,但是关于草原生态系统的氮素平衡过程的系统研究迄今尚未开展。地下器官中贮藏养分的积累是多年生牧草抵御不良环境条件的物质保障,碳水化合物是我国典型草原植物重要的贮藏营养物质。但是关于我国草原生态系统贮藏养分的研究还相当匮乏。值得一提的是,不合理的人类活动也加剧了草地生态系统氮素的损失,甚至对全球环境和人类健康产生了重要影响。为此,我们在中国科学院内蒙古草原生态系统定位研究站的羊草样地设计了氮素添加试验,采用15N稀释法对典型草原羊草群落的氮素吸收利用、氮素平衡进行了研究,并就氮素添加条件下,植物氮素利用与植物竞争的关系、氮素吸收分配与牧草生物产量与品质的关系进行了探讨。同时采用高效液相色谱对羊草群落植物贮藏碳水化合物的种类与含量进行了测定。 15N稀释法的试验结果表明:我国典型草原羊草群落吸收的氮素平均16.41%来源于肥料,83.59%来源于土壤。氮素添加不仅显著促进了羊草群落地上器官对肥料氮索和土壤氮素的吸收量,而且促进了地下器官对肥料氮素和土壤氮素的吸收量。生物量达到最大时,羊草群落吸收的氮素分配到地下器官中的比例平均为74.85%,分配到地上器官中的比例平均为25.15%。植物吸收的肥料氮素在地上和地下器官之间的分配比例约各占50%。 在我国典型草原羊草群落,植物对肥料氮素的回收率仅为31.61%,氮素添加显著影响羊草群落植物对肥料氮素的回收,随着氮素添加量的提高,地上和地下植物器官对肥料氮素的回收量均显著提高。凋落物的肥料氮素回收率为2.92%,地下凋落物的回收率显著高于地上凋落物。肥料氮素的土壤存留率为36.16%,主要分布在地表至40cm的土层范围内(>95%)。各土层存留的标记肥料氮素量均随着氮素添加量的增加而显著提高。肥料氮素的当季损失率为21.77%-43.38%。风险:收益分析表明,在本试验条件下,添加5.25gN/m2与28gN/m2的处理风险大于收益,添加17.5g/m2的处理风险最低,收益最高,在草原生态系统的管理中可以参考。 为了了解羊草群落植物的竞争能力是否对羊草群落植物的相对多度有影响,我们对不同盖度的10个物种的15N吸收速率、15N分配、植物组织氮素含量、单株生物量、根/冠比、氮素生产力等反映植物竞争能力的指标进行了测定和分析。发现向根系的氮素分配比例、根/冠比、和氮素生产力与植物的相对盖度显著正相关,向地上器官的氮素分配比例、氮素吸收速率与相对盖度呈显著负相关,而植物组织氮素含量、和单株生物量与植物相对盖度无关。 试验前,我们认为氮素吸收速率应该与植物的相对多度显著正相关,但是本试验发现却是显著负相关。这一结果说明,高的氮素吸收速率并不能代表较高的竞争能力,而是稀少植物能够与优势植物共存的一种生理机制。 氮素的吸收与分配显著地影响牧草的生物产量和品质。氮素添加提高了羊草生物量,促进了生物量向地上器官的分配比例,降低了向根系的分配比例,使根/冠比显著降低。氮素添加促进了羊草对氮素的吸收以及向茎叶中的分配比例,降低了向根系的分配比例,提高了羊草各器官的氮素含量和地上器官的蛋白质含量,对根系的蛋白质含量无显著影响。本试验条件下,氮素添加水平为17.5gN/m2时,羊草根、茎、叶生物产量均最高。与17.5gN/m2的处理相比较,添加28gN/m2的处理,羊草的生物产量以及牧草蛋白质含量均无显著差异。初步认为,本实验条件下,17. 5gN/m2是较为适宜的氮素添加量。 地下器官中贮藏养分的积累是多年生牧草抵御不良环境条件的物质保障,碳水化合物是我国典型草原植物重要的贮藏营养。采用高效液相色谱(HPLC)对羊草群落地下器官的贮藏性碳水化合物进行了分析。结果表明,羊草群落地下贮藏碳水化合物种类主要包括甘露糖醇、果聚糖、蔗糖、葡萄糖和果糖。其中甘露糖醇是最主要贮藏碳水化合物,约占60%;其次是果聚糖,约占30%。氮素添加量对羊草群落地下贮藏碳水化合物有显著影响。在0~50 g NH4N03. m-2.yr-1范围内,随着氮素添加量的增加,总糖、果聚糖、甘露糖醇的含量均逐渐升高。氮素添加时期对羊草群落地下贮藏碳水化合物含量亦有显著影响。7月初(雨季)添加氮素比4月份(牧草开始返青)更有利于牧草地下贮藏碳水化合物的积累。 对羊草根茎中的贮藏性碳水化合物的测定结果表明,羊草根茎中的贮藏碳水化合物组分主要包括果聚糖、甘露糖醇、蔗糖、葡萄糖和果糖。其中果聚糖是最主要贮藏碳水化合物,约占60%:其次是甘露糖醇,约占20%。氮素添加量对羊草根茎中的贮藏碳水化合物有显著影响。在0~17.5 g N/m2范围内,随着氮素添加量的增加,总糖、果聚糖、甘露糖醇的含量均逐渐升高。氮素添加时期对羊草根茎中的贮藏碳水化合物的含量亦有显著影响。在7月初添加氮素比4月份添加氮素更有利于贮藏碳水化合物的积累。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The Hainan gibbon (Nomascus hainanus) is one of the most endangered primates in the world, confined to mature natural forest in Hainan Island, China. We assessed changes in habitat condition on the island between 1991 and 2008, using vegetation maps generated by remote-sensing images. We defined forest suitable for gibbons based on composition, tree size and canopy cover. During the 17-year period, the area of suitable gibbon forest decreased by 540 km(2) (35%) across the whole island, and by 6.3 km(2) (7%) in the locality of the sole remaining gibbon population at Bawangling National Nature Reserve. The forest patches large enough (>1 km(2)) to support a gibbon group decreased from 754 km(2) to 316 km(2) in total area, and from 92 to 64 in number. Suitable natural forest was mainly replaced by plantations below 760 m, or degraded by logging, grazing and planting of pines above 760 m. Meanwhile, forests in former confirmed gibbon areas became more fragmented: mean area of patches decreased by 53%. We mapped the patches of natural forest in good condition which could potentially support gibbons. We recommend a freeze on further expansion of plantations between core patches at Bawangling, Jiaxi-Houmiling and Yinggeling Nature Reserves in accordance with forest protection regulations; establishment of nature reserves in currently unprotected natural forest patches elsewhere in line with the local government's nature reserve expansion policy; and active natural-forest restoration between remaining fragments at Bawangling. (C) 2010 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

 采用聚类分析测定云南地区9 个国家自然保护区珍稀濒危哺乳动物分布格局的相似性。以编码为 1 的有物种分布及编码为0 的无物种分布作为二元状态,建立二元数据列联表,应用类与类的空间距离Dpq聚类。 结果表明,珍稀濒危哺乳动物的分布未出现纬度梯度变异,横断山区省为一类,西南区省和华南区省与云南动物地 理区划系统基本一致,相邻保护区无量山与哀牢山分别为一类。在保护区之间应建立生物廊道,以促进物种基因 的交流,扩大面积较小的保护区,合并面积相对小的保护区。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The South China tiger Panthera tigris amoyensis is the rarest of the five living tiger subspecies, the most critically threatened and the closest to extinction. No wild South China tigers have been seen by officials for 25 years and one was last brought into captivity 27 years ago. The 19 reserves listed by the Chinese Ministry of Forestry within the presumed range of the tiger are spatially fragmented and most are too small to support viable tiger populations. Over the last 40 years wild populations have declined from thousands to a scattered few. Despite its plight and occasional anecdotal reports of sightings by local people, no intensive field study has been conducted on this tiger subspecies and its habitat. The captive population of about 50 tigers, derived from six wild-caught founders, is genetically impoverished with low reproductive output. Given the size and fragmentation of potential tiger habitat, saving what remains of the captive population may be the only option left to prevent extinction of this tiger subspecies, and even this option is becoming increasingly less probable. This precarious dilemma demands that conservation priorities be re-evaluated and action taken immediately to decide if recovery of the wild population will be possible.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is currently limited to the middle and lower reaches of the Yangtze River from Yichang to Shanghai, China, and the adjoining Poyang and Dongting Lakes. Its population size has decreased remarkably during the last several decades due to the heavy impact of human activities, including overfishing of prey species, water development projects that cause attendant habitat loss and degradation, water pollution, and accidental deaths caused by harmful fishing gear and collisions with motorized vessels. It was estimated that the number of remaining individuals was down to approximately 1800 in 2006, a number that is decreasing at a rate as high as 5% per year. Three conservation measures - in situ and ex situ conservation and captive breeding have been applied to the protection of this unique porpoise since the early 1990s. Seven natural and two "semi-natural" reserves have so far been established. Since 1996, a small group of finless porpoises has been successfully reared in a facility at the Institute of Hydrobiology of the Chinese Academy of Sciences; three babies were born in captivity on July 5, 2005, June 2, 2007 and July 5, 2008. These are the first freshwater cetaceans ever born in captivity in the world. Several groups of these porpoises caught in the main stream of the Yangtze River, or rescued, have been introduced into the Tian'e-Zhou Semi-natural Reserve since 1990. These efforts have proven that, not only can these animals survive in the area, they are also to reproduce naturally and successfully. More than 30 calves had been born in the reserve since then, with one to three born each year. Taking deaths and transfers into account, there were approximately 30 individuals living in the reserve as of the end of 2007. Among eight mature females captured in April 2008, five were confirmed pregnant. This effort represents the first successful attempt at off-site protection of a cetacean species in the world, and establishes a solid base for conservation of the Yangtze finless porpoise. A lesson must be drawn from the tragedy of Chinese River Dolphin (Lipotes vexillifer), which has already been declared likely extinct. Strong, effective and appropriate protective measures must be carried out quickly to prevent the Yangtze finless porpoise from becoming a second Chinese River Dolphin, and save the biodiversity of the Yangtze River as a whole.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The effects of organic-rich sediment and sulfide exposure on Hydrilla verticillata were investigated. The organic richness of sediment was simulated by adding sucrose into sediments, and sulfide exposure was conducted by adding sodium sulfide to plant roots. The length, biomass and density of shoot reduced in the sucrose-amended sediments, and the largest reduction occurred in the highest 1.0% addition treatment by 84.2%, 56.7% and 92.4%, respectively. However, the 0.1% addition treatment stimulated the growth of root. The effects of below-ground sulfide exposure on the physiological activities of H. verticillata were determined by adding sulfide to the below-ground tissue. Significantly inhibitory effects of sulfide were observed on plant photosynthesis, root carbohydrate and nitrogen synthetic reserves. The net photosynthetic rates, soluble carbohydrate and soluble protein contents in root were reduced by 104%, 71.8% and 49.8%, respectively, in the 0.6 mM sulfide treatment.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Despite it is widely acknowledged that the ability to hydrolyze dissolved organic matter using extracellular phosphatases is diverse in fresh water phytoplankton, the competition within single species related to presence and quantity of cell-surface-bound phosphatases has not been examined in natural conditions yet. Here, we studied phytoplankton species competition in a freshwater reservoir during an in situ experiment. A natural plankton community, with the exclusion of large zooplankton, was enclosed in permeable dialysis bags inside two large containers of different bioavailable phosphate concentrations. Phytoplankton species biomass and the abundance of bacteria were determined in purpose to compare the development of enclosed microbial communities. Total and cell-surface-bound phosphatase activities in the phytoplankton were investigated using the Fluorescently Labelled Enzyme Activity (FLEA) technique that allows for direct microscopic detection of phosphatase-positive cells and, with image cytometry, enables quantification of phosphatase hydrolytic capacity. Production of extracellular phosphatases was not completely inhibited or stopped in the phosphate-enriched environment, phytoplankton cells only showed the activity less often. Under the phosphate-nonenriched conditions, the production of phosphatases was enhanced, but active species did not proliferate amongst phytoplankton assemblage. Further, specific growth rates of the phosphatase-positive species in the non-enriched environment were lower than the same phosphatase-positive species in phosphate-enriched environment. Interestingly, the phosphatase-positive cells of Ankyra ancora increased their size in both treatments equally, although the population in phosphate-enriched environment grew much faster and the cell-specific phosphatase activity was lower. We hypothesize that brand new daughter cells had sufficient phosphorus reserves and therefore did not employ extracellular phosphatases until they matured and needed extra bioavailable phosphorus to support their metabolism before cell division. Based on presented in situ experiment, we propose that the ability to hydrolyze organic polymers and particles with cell-surface-hound phosphatases is advantageous for longer persistence of given population in a phosphate-scarce environment; although phosphatase-positive species cannot dominate the reservoir phytoplankton solely because of specific phosphorus-scavenging strategy.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Transgenic animals with improved qualities have the potential to upset the ecological balance of a natural environment. We investigated metabolic rates of 'all-fish' growth hormone (GH) transgenic common carp under routine conditions and during starvation periods to determine whether energy stores in transgenic fish would deplete faster than controls during natural periods of starvation. Before the oxygen uptake was measured, the mean daily feed intake of transgenic carp was 2.12 times greater than control fish during 4 days of feeding. The average oxygen uptake of GH transgenic fish was 1.32 times greater than control fish within 96 h of starvation, but was not significantly different from controls between 96 and 144 h of starvation. At the same time, GH transgenic fish did not deplete energy reserves at a faster rate than did the controls, as the carcass energy contents of the two groups following a 60-d starvation period were not significantly different. Consequently, we suggest that increased routine oxygen uptake in GH transgenic common carp over that of control fish may be mainly due to the effects of feeding, and not to an increase in basal metabolism. GH transgenic fish are similar to controls in the regulation of metabolism to normally distribute energy reserves during starvation. (c) 2008 Published by Elsevier B.V.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background, Aim and Scope. There are two species of fresh water cetaceans surviving in the Yangtze River system in China: Baiji (Lipotes vexillifer) and Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis). As a result of the expansion of human activities on the river, their distribution ranges appear to be decreasing and in the case of the Baiji, are even being restricted to several sections. The Baiji is the world's most critically endangered cetacean species with a population estimated at only a few tens of individuals. The Yangtze finless porpoise is the world's only freshwater-adapted population of the species, and it has been estimated that only around 1,000 individuals remain in the river system. In order to prevent the extinction of Baiji and a sharp decline in the abundance of the porpoise, in situ conservation (i.e. in the river) and two ex situ conservation (i.e. in semi-natural reserves and in captivity) strategies were proposed and have been implemented since the early 1990s. In view of both the severely endangered status of the animals and the severely degraded conditions of their habitats, the feasibility and actual status of these two strategies are raised for discussion. Main Features. The threats faced by the cetaceans are mainly from the unfettered exploitation of the river's resources. In the past 20 years, five nature reserves have been established along the river. Imposing maximum prohibition of harmful and illegal fishing methods in the reserves might prolong the process of extinction of these cetaceans in the wild, but so far, the administrative measures taken in the reserves have not yet kept the abundance from sharply declining. As human use of the river and its resources is expected to intensify for many decades into the future, the ability of the river to continue to support these species is certainly undecided. Therefore, rescuing animals from the river and establishing viable breeding populations in semi-natural reserves, in which the environment is similar to the main stream of the river, and in captivity, has to be considered urgently as the short-term goal of ex situ strategies. Since the abundance of porpoises is higher than that of the Baiji, we have first established breeding populations of them in the semi-natural reserves and in captivity. But, considering the extremely low density of Baiji in the river, an immediate range-wide Yangtze Baiji survey is an urgent need for locating and capturing sufficient Baiji for successfully establishing a breeding population of them in semi-natural reserves. Results. Two semi-natural reserves (in Shishou, Hubei Province, and Tongling, Anhui Province) have been set up along the river in order to establish breeding populations of the Baiji and the porpoises. So far, several small groups of porpoises that were caught in the main stream of the river have successively been introduced into the semi-natural reserves. Under careful management, these animals in both of the semi-natural reserves not only survive, but can also reproduce naturally and successfully. At least one or three calves were born in each reserve each year. Additionally, a breeding group of porpoises is being established at the Baiji Dolphinarium at the Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan. There are presently four adults and one calf living in the Dolphinarium. The calf, born in July, 2005, is the first captive bred Yangtze Finless Porpoise in the world. In preparation for the range-wide Yangtze cetacean survey, a 9-day pilot expedition on the river near Wuhan was conducted in March, 2006, in order to develop methods for locating the Baiji. No Baiji were expected to be seen in such a short period but about 40 porpoise sightings were observed. Results of the pilot survey indicated that traditional visual and acoustical survey methods for cetaceans should be adapted to find the elusive Baiji in the river. Currently, the range-wide Yangtze cetacean survey is in preparation. The survey will cover over 1,700 km of the Yangtze River from Yichang to Shanghai, and is expected to provide detailed information on Baiji and porpoise numbers and distribution patterns in the river. Discussion. Although the short-term goal of ex situ conservation is to rescue cetaceans from the river and to establish viable breeding populations in semi-natural reserves and in captivity, the long-term goal of releasing the animals back into the river when the threats have decreased and the natural environment has been improved, should not be neglected. Moreover, the in situ conservation efforts in the natural reserves, and even in the entire Yangtze River system, including the lakes, should not be ignored or abandoned at any time. The activities contributing to the conservation of the Baiji and the porpoise in the wild have the incidental effect of benefiting the entire Yangtze ecosystem and other rare threatened species. The dynamics of the groups of porpoises in semi-natural reserves should be monitored continually, in order to guide the establishment of breeding groups of Baiji in these semi-natural reserves in the near future. Conclusions. Under the existing severely degraded conditions of the Yangtze system, the sharply fall populations of Baiji and porpoises will not be suspended in the foreseeable future. Therefore, ex situ conservation should be emphasized, and the severely threatened Baiji in the river should be removed and translocated to semi-natural reserves for establishing viable breeding populations. The successful program of capturing, translocating and maintaining finless porpoises in the Shishou semi-natural reserve has demonstrated its adequacy as an ex situ environment for cetaceans. Following the successful pilot survey in the river, the immediate range-wide Yangtze cetacean survey is proposed and is in preparation. The range-wide survey is expected to ensure that any remaining Baiji can be found reliably and captured successfully after the survey. Recommendations and Perspectives. During the range-wide survey, not only the Baiji but also the porpoise as well as their habitats should be investigated based on visual and acoustical methods that adapted to the river and the animals. Meanwhile, the current risk levels to the Baiji and porpoises should be evaluated at each area where Baiji or porpoises can be reliably sighted. Any capture efforts should be targeted on the most threatened areas, or where there is maximum risk of injury or death. The immediate track of the Baiji should be carried out once a Baiji is sighted during the range-wide survey in order to obtain the movement route of the animals, which is crucial information for the successful capture operation. Additionally, the need to establish new semi-natural reserves for the porpoises should be placed on the agenda of local and central governments in the near future.