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361.
缅甸达贡山风化壳型硅酸镍矿床   总被引:2,自引:0,他引:2  
程迁群  罗太旭 《云南地质》2009,28(4):420-424
矿床产于超基性岩顶部的风化壳硅镁镍矿层中,超基性岩方辉橄榄岩是成矿母岩和矿体直接载体。矿石为硅酸镍氧化矿石,镍以类质同象存在于硅酸盐矿物中。具有典型的风化壳型硅酸镍矿床特点。  相似文献   
362.
两种统计分析模型在CVM应用中的比较研究   总被引:8,自引:1,他引:7  
李华生  徐慧  彭补拙 《地理科学》2007,27(1):115-120
学术界普遍认为条件价值法(CVM)是生物多样性非使用价值评估的唯一方法,但其中存在许多问题需进一步完善。针对条件价值法评估结果的准确性和有效性问题,以安徽省鹞落坪国家级自然保护区为例,通过将以往一贯采用的单纯随机抽样评估模型与分层随机抽样评估模型结果的分析比较,认为分层抽样评估模型可在一定程度上提高评估结果准确性和有效性。  相似文献   
363.
A households′production behavior directly influences the quality of the environment and determines the successful development of nature reserves.Meanwhile,the households′production behaviors are complicated by interrelated factors,such as protection attitudes,resource endowment,and family wealth.This research evaluated households near the Crested Ibis National Nature Reserve in Shaanxi Province,acquiring data from 436 households around Yang County and Ningshan County in the south slope of Qinling Mountains,China.Based on the collected data,we developed a structural equation model to evaluate the coupling relationships among households′ protection attitudes,production behaviors,resource endowment,and family wealth.The results showed that:1) households with great resource endowment had more negative attitudes,probably due to their greater protection costs;2) the households with higher education levels had worse protection attitudes;3) the households with more family wealth were likely to use fewer fertilizers,pesticides,and firewood;4) the households with more resource endowment showed less production and management behaviors;5) the enhancement of households’ attitudes improved production behaviors to protection the environment,but the effects were not statistically significant.Our results provide a basis for the government’s protection policy making,exploring the effective management measures that are beneficial for both nature reserve management and community development.  相似文献   
364.
We investigated the quantity and quality 0f fallen l0gs in different Tsuga l0ngibracteata f0rest c0mmunities in the Tianba0yan Nati0nal Nature Reserve. We used redundancy analysis t0 determine the spatial distributi0n 0f fallen l0gs in the different f0rest c0mmunities and t0 analyze the relati0nships am0ng stand structure, t0p0graphic fact0rs and human disturbance. The v0lume, c0vered area, mean l0g length and number 0f fallen l0gs differed significantly am0ng f0rest types (P 〈 0.05), but mean diameter at breast height sh0wed n0 significant difference (P 〉 0.05). The l0g v0lume and c0vered area in different f0rest types sh0wed the f0ll0wing trend: T. l0ngibracteata pure f0rest 〈 T. l0ngibracteata + Olig0staehyum scabrifl0rur 〈 T. l0ngibraeteata + hardw00d 〈 Rh0d0dendr0n simiarum + T. l0ngibraeteata 〈 T. l0ngibraeteata + Phyll0stachys heter0cycla pubescens. The spatial distributi0n patterns 0f l0gs quantity and quality indicated that l0g v0lume and c0vered area were str0ngly affected by envir0nmental fact0rs in the f0ll0wing 0rder: human disturbance 〉 elevati0n 〉 sl0pe p0siti0n 〉 b0le height 〉 tree height 〉 sl0pe aspect 〉 density 〉 basal area 〉 sl0pe gradient. The relative c0ntributi0n 0f envir0nmental variables 0n the t0tal variance was t0p0graphy (76%) 〉 disturbance (42%) 〉 stand structure (35%). T0p0graphy and disturbance c0mbined explained 8.2% 0f the variance. Fallen l0~s auantitv and aualitvwere negatively related t0 elevati0n and sl0pe p0siti0n, and p0sitively ass0ciated t0 human disturbance. The l0g v0lume decreased fr0m n0rthern t0 s0uthern sl0pes. Envir0nmental fact0rs had the highest impact 0n class I (slightly decayed), and l0west impact 0n class V (highly decayed).  相似文献   
365.
Several previous studies have reported high levels of genetic differentiation between populations inside European Marine Reserves and their adjacent coastlines for a direct‐developing species. These studies suggest that sea loughs may not represent the most suitable sites for inclusion into Marine Protected Area (MPA) or Marine Reserve networks as they are not well connected to other populations. However, many marine species have pelagic larvae, and the connectivity of populations of such species inside sea loughs with non‐lough populations remains unknown. Here, I investigated the levels of gene flow between populations of the acorn barnacle Semibalanas balanoides inside and outside Strangford Lough, Northern Ireland; this species has a long‐lived pelagic larvae (4–6 weeks). There were no significant differences in the levels of genetic diversity between sea lough and non‐lough populations and no evidence for genetic differentiation between any of the populations examined; the populations appear well mixed and well connected, in contrast to what has been reported for a previous direct‐developing species.  相似文献   
366.
依据中国西北干旱区生态环境的特性和演化规律,从气候条件、土地资源、生境状态及人为干预4方面筛选12个指标,构建西北干旱区自然保护区生态脆弱性评价指标体系,并对各指标进行分级.采用层次分析法确定指标权重,建立生态脆弱性综合评价模型.在甘肃敦煌西湖自然保护区和苏干湖自然保护区应用表明,指标体系合理,模型适用.评价认为,西湖自然保护区目前总体状态为中,高度脆弱,苏干湖自然保护区为轻,中度脆弱.在原生脆弱性方面,两者等级相当,但西湖更脆弱;在次生脆弱性方面,西湖已受到显著影响,次生脆弱性严重.  相似文献   
367.
选择2005与2012年两期遥感影像,基于RS/GIS技术和转移矩阵数学模型,从景观转移方面对保护区景观要素时空变化进行定量分析,探讨了双河自然保护区在7年内土地利用格局及土地转化规律.结果表明,林地、灌木及草地之间转化较为突出,与保护区的环境因素有直接关系.沼泽、水域、居民地及裸土地因其面积基数小,类间转化量较小.旱田较活跃,除居民地外,其余6类景观都有面积转化为旱地.林地和草地相互转化较为活跃,灌木和林地相互转化较为活跃.研究结果可以为保护区的生态治理和可持续发展规划提供科学依据.  相似文献   
368.
In order to investigate the feasibility of reintroducing the South China tiger (Panthera tigris amoyensis) in the Jiangxi Matoushan National Nature Reserve, field surveys were conducted to assess prey distribution in the reserve. Twelve permanent transects were set in three distinct functional zones from February to April 2012 and May to July 2013. A total of 112 ungulate signs were recorded on these transects. In addition, 20 camera traps were used to survey ungulates and predators in 2012, while the following year we extended the survey site by using 30 cameras. Overall, 6641 capture events on 2930 camera days were obtained, presenting a variety of ungulate species: muntjak (Muntiacus muntjak), tufted deer (Elaphodus cephalophus), serow (Capricornis sumatraensis) and wild boar (Sus scrofa). Population structure and composition of ungulates was compared in different functional zones using a single factor of variance analysis in SPSS software. Significant differences in the distribution of ungulates were recognized between the core zone and experimental zone, but not in other zones due to differences in habitat types and management practices of the nature reserve. Using ArcGIS analysis and Salford Predictive Modeler software, we ran several predictive models to understand which areas are most suitable for ungulates. We conclude that muntjac and wild boar are mainly distributed in the experimental zone, serow are more common in the core zone, while tufted deer are located evenly in the three functional zones. Finally, suggestions for effective and feasible management strategies and techniques for Matoushan National Nature Reserve were recommended based on the results and analysis in this study.  相似文献   
369.
近30年珠穆朗玛峰国家自然保护区冰川变化的遥感监测   总被引:18,自引:2,他引:16  
利用1976、1988和2006年的3期陆地卫星遥感数据,采用面向对象的解译方法并结合专家知识分类规则自动提取珠穆朗玛峰国家自然保护区(以下简称珠峰保护区)3个时期的冰川信息,并利用遥感、地理信息系统和图谱的方法对冰川时空分布特征和变化及其原因与不确定性进行了分析。结果如下:(1)2006年珠峰保护区内冰川面积为2710.17±0.011km2,为研究区总面积的7.41%,主要分布在研究区南部海拔4700~6800m的高山区;(2)1976-2006年,珠峰保护区冰川持续退缩明显,总面积减少501.91±0.035km2,冰湖扩张迅速(净增加36.88±0.035km2);研究区南坡子流域冰川退缩率(16.79%)高于北坡子流域(14.40%);珠峰保护区冰川以退缩为主,退缩冰川主要分布于海拔4700~6400m,退缩区上限海拔为6600~6700m;(3)1976年以来,气温显著上升和降水减少是冰川退缩的关键因素。  相似文献   
370.
Reserve (or field) growth, which is an appreciation of total ultimate reserves through time, is a well-recognized phenomenon, particularly in mature petroleum provinces. The importance of forecasting reserve growth accurately in a mature petroleum province made it necessary to develop improved growth functions, and a critical review of the original Arrington method was undertaken. During a five-year (1992–1996), the original Arrington method gave 1.03% higher than the actual oil reserve growth, whereas the proposed modified method gave a value within 0.3% of the actual growth, and therefore it was accepted for the development for reserve growth models.During a five-year (1992–1996), the USGS 1995 National Assessment gave 39.3% higher oil and 33.6% lower gas than the actual growths, whereas the new model based on Modified Arrington method gave 11.9% higher oil and 29.8% lower gas than the actual growths. The new models forecast predict reserve growths of 4.2 billion barrels of oil (2.7%) and 30.2 trillion cubic feet of gas (5.4%) for the conterminous U.S. for the next five years (1997–2001).  相似文献   
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