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61.
程杰  呼天明  程积民 《生态学报》2010,30(10):2630-2638
植被是区域气候与环境的综合反映,研究特定地区草地植被与气候变化的关系,寻找影响植被变化的关键因子,是植被重建和生态环境恢复的前提。利用1957-2008年的气候数据和1982-2008年的植被定位监测资料,分析了黄土高原半干旱区的宁夏云雾山植被动态变化规律及其与温度和降水的关系。结果表明:51a来,该区年平均温度明显升高,而年平均降水量总体呈减少趋势,显示黄土高原地区气候暖干化趋势明显。统计分析表明,研究区年平均温度对植被的重要值年际变化有极显著影响(P0.01),而年降水量与植被的重要值呈极显著正相关(P0.01),表明气候持续干旱化对该区植被的生长有较大影响,该区降水的多寡是直接影响植被生长优劣的决定性因子,改善区域水分状况和封禁是推进植被恢复与重建的主要措施。  相似文献   
62.
The seed coat morphology, investigated in taxa representative of the main European groups ofAconitum, are in good agreement with the current taxonomy of the genus. The seed coat microcharacteristics (warty epidermal cells) are very constant. There is a trend for the reduction of longitudinal wings on the edges concomitant with the development of ridges and transverse wings on the faces. Another morphological progression leads from smooth to rugulose and eventually to transverse wing-bearing seed faces. A working hypothesis suggests an ecological adaptative significance to these changes.  相似文献   
63.
三峡水库的运行,改变了其坝下游的水沙情势,使坝下游沙洲生境呈现出明显的水淹强度梯度变化。阐明这一梯度变化下沙洲植被组成、分布和性状结构特征,是理解植被与沙洲稳定关系的基础,更是阐明三峡工程对长江中下游地区生态环境影响的核心内容之一。选取上荆江河段第一个江心洲-太平口心滩作为研究样地,通过植被组成和分布特征的调查,对不同水淹强度下群落物种组成、多样性和功能特征进行了深入分析。结果表明:太平口心滩植被组成以草本植物为主,稀布小型灌木川三蕊柳。调查共记录物种21科33属39种,以禾本科和菊科植物为主要优势种。轻微(20-40 d)和极强水淹强度(100+d)条件下的生境物种组成同其他水淹强度生境具有显著性差异,轻微水淹强度下牛鞭草和节节草为主要优势种,极强水淹强度下虉草为主要优势种。不同水淹强度下物种多样性指数差异显著,功能多样性指数和生物多样性指数趋势基本一致。随着水淹时间的延长,植被更倾向于表现出花果期位于出露期、植株高度更加低矮、须根系、进行营养繁殖的功能性状。江心洲植被的群落结构和功能性状特征都在水淹梯度下呈现出明显的梯度变化特征。这些研究结果表明水淹强度的梯度变化是沙洲植物群落变化的重要驱动因子,为进一步研究沙洲植物群落动态变化以及沙洲植被协同演替机制,明晰大坝影响下的生态环境变化提供重要依据。  相似文献   
64.
As we confront the current environmental crisis, determining the biophysical base (e.g., materials, energy, land, and water) of nations has become paramount. With advanced economies benefiting from the import of resource-intensive primary goods originating from poorer parts of the world, especially emerging nations, these are dilapidating their natural capital. Brazil is one of such emerging economies, whose mining and farming activities, propping up its export-led economic growth, exert great pressure on the environment. In particular, farming has been shown to have one of the world's greatest environmental impacts, especially as a consequence of land use associated with cattle ranching. Since a nation-wide evaluation of land-use types across the whole sectorial spectrum of the country's economy is still lacking, we used the most recently available Input–Output Economic Model for Brazil and the Ecological Footprint method to identify those economic sectors with the greatest potential for appropriating portions of the natural world.Our results show that: (i) the biggest chunk of Brazil's Ecological Footprint is due to its Carbon Footprint and, in particular, emissions from cattle; (ii) only a few economic sectors exhibit high Ecological Footprint values, chiefly those belonging to livestock farming and energy production based on fossil fuels; (iii) excluding the soybeans and slaughter sectors, export-oriented sectors have below-average Ecological Footprint values; and (iv) the percentage of Brazil's Ecological Footprint due to household consumption (excluding imports) is three times bigger than that attributable to exports, with sectors belonging to livestock farming contributing the most to such disparity.These results underscore that the environmental impact of the Brazilian economy can be drastically reduced by tackling the emission-intensive production processes of a few sectors only and disincentivizing the domestic consumption of a narrow range of products, especially with respect to the livestock segment.  相似文献   
65.
随着人民生活水平提高,物质生活富裕,传统家庭结构发生了变化和工作压力的增大,人际关系逐渐趋于淡化,使越来越多的人将感情投注于宠物身上,宠物与人类的关系已经发生了变化,人们越来越注重休闲生活情趣的培养,不再以追求温饱为主要目标,人与宠物间的依赖关系,随着时间的流逝而日益浓厚。饲养的犬猫不再扮演看门和捉老鼠的角色,而是人类休闲时的玩伴。在社会提倡人与人之间关爱的同时,也提升了人们对动物福利的理念,对社会的关爱和爱心,但他们迫切需要兽医医疗、疫病防控和饲养管理的指导。怎样将兽医知识教育公众并增加公众对饲养宠物的理解、对人兽共患病的认识,对所有影响动物福利问题的意识是我们的责任。伴随着宠物数量的增长,围绕宠物经济和宠物行业的发展催生了一些新兴的产业,这些产业带来的不仅是相关产品的诞生,我们看到了这些产业上升的空间和它的发展前途,成就了人们的就业和再就业,同时也给宠物行业带来了不可估量的经济效益,并对社会产生了巨大的社会价值和难以估计的经济产值。目前国内宠物市场已进入一个高速发展的时期,全球发达国家都将目光投向了中国日益增长的消费水平,这也标志着中国宠物市场发展的时机已经成熟。宠物市场涌现出的商机不可小觑,也正是我们看到的中国巨大的商机。以宠物为主题的产业日新月异,中国的宠物行业将迈上一个新的台阶。  相似文献   
66.
福建省生态保护重要性评价   总被引:1,自引:2,他引:1  
生态保护重要性是表征区域生态系统结构和功能重要性程度的综合指标,确定生态保护空间范围是协调保护与发展、保障生态服务持续供给的基础。在明确福建省生态本底和关键生态问题的基础上,综合分析生态服务功能重要性和生态敏感性,构建福建省生态保护重要性评价指标体系,识别具有重要保护意义的生态极重要地区,能够为优化生态保护策略、划定生态红线和主体功能区划提供技术支持。研究结果表明,福建省生态保护极重要区占福建省陆地总面积的38.94%,生态重要性空间格局基本沿福建省闽西大山带、闽中大山带与海岸带分布,其中生态服务功能极重要区面积为3.96万km~2,以生物多样性维护功能和水源涵养功能为主;生态极敏感性区面积占福建省陆地总面积的9.71%,水土流失是主要的生态问题,占福建省陆地总面积的8.93%,土地沙化极敏感区集中在海岸带附近,与海岸侵蚀极敏感区空间范围基本一致。研究建议,生态保护极重要区作为划定生态红线和重点生态功能区的依据,支撑福建省开展有针对性的生态保护,保障和维护生态安全。  相似文献   
67.
In cerebellum, 13 different GABA(A) receptor subunits are expressed. The number of different receptor subtypes formed in this tissue, their subunit composition and their quantitative importance so far has not been determined. In the present study, immunodepletion by immunoaffinity chromatography, as well as immunoprecipitation and western blot analysis was performed using 13 different subunit-specific antibodies to provide an overview on the subunit composition and abundance of GABA(A) receptor subtypes in mouse and rat cerebellum. Results obtained indicate that alpha1betaxgamma2, alpha1alpha6betaxgamma2, alpha6betaxgamma2, alpha6betaxdelta and alpha1alpha6betaxdelta are the major GABA(A) receptor subtypes present in the cerebellum. In addition, small amounts of alpha1betaxdelta receptors and a series of minor receptor subtypes containing alpha2, alpha3, alpha4, alpha5, gamma1 or gamma3 subunits are also present in the cerebellum. Whereas the abundance of alpha1alpha6betaxgamma2, alpha6betaxdelta and alpha1alpha6betaxdelta receptors is different in mouse and rat cerebellum, that of other receptors is quite similar in these tissues. Data obtained for the first time provide an overview on the GABA(A) receptor subtypes present in the cerebellum and represent the basis for further studies investigating changes in receptor expression and composition under pathological conditions.  相似文献   
68.
渤海东部海域秋季底层游泳动物种类组成及群落多样性   总被引:2,自引:0,他引:2  
根据2014年9月在渤海东部海域(37°40'—38°20'N、120°00'—121°20'E)进行的游泳动物底拖网调查数据,应用相对重要性指数、生物多样性指数、群落结构多元统计分析等方法对该海域游泳动物种类组成及群落多样性特征进行了分析。结果表明:调查海域共捕获游泳动物54种,以头足类枪乌贼(Loliolus spp.)为绝对优势种;游泳动物资源密度为28.82kg/h和5166尾/h。游泳动物种类Margalef丰富度指数(D)的变化范围为1.99—3.67,Shannon-Wiener多样性指数(H')变化范围为0.89—2.28,Pielou均匀度指数(J')变化范围为0.29—0.69。群落结构多元统计分析表明,渤海东部海域游泳动物群落结构以60%的相似性可划分为3个组群:长岛群岛海域组群(A组群)、龙口海域组群(B组群)和蓬莱海域组群(C组群);ANOSIM分析表明,组群之间差异极显著,两两之间差异亦极显著。受增殖放流影响,C组群资源密度和种类多样性均保持较高的水平,而A、B组群人为活动频繁,过度捕捞严重,对海域生态环境和渔业资源整体结构的破坏较大。  相似文献   
69.

Aim

Ideally, datasets for species distribution modelling (SDM) contain evenly sampled records covering the entire distribution of the species, confirmed absences and auxiliary ecophysiological data allowing informed decisions on relevant predictors. Unfortunately, these criteria are rarely met for marine organisms for which distributions are too often only scantly characterized and absences generally not recorded. Here, we investigate predictor relevance as a function of modelling algorithms and settings for a global dataset of marine species.

Location

Global marine.

Methods

We selected well‐studied and identifiable species from all major marine taxonomic groups. Distribution records were compiled from public sources (e.g., OBIS, GBIF, Reef Life Survey) and linked to environmental data from Bio‐ORACLE and MARSPEC. Using this dataset, predictor relevance was analysed under different variations of modelling algorithms, numbers of predictor variables, cross‐validation strategies, sampling bias mitigation methods, evaluation methods and ranking methods. SDMs for all combinations of predictors from eight correlation groups were fitted and ranked, from which the top five predictors were selected as the most relevant.

Results

We collected two million distribution records from 514 species across 18 phyla. Mean sea surface temperature and calcite are, respectively, the most relevant and irrelevant predictors. A less clear pattern was derived from the other predictors. The biggest differences in predictor relevance were induced by varying the number of predictors, the modelling algorithm and the sample selection bias correction. The distribution data and associated environmental data are made available through the R package marinespeed and at http://marinespeed.org .

Main conclusions

While temperature is a relevant predictor of global marine species distributions, considerable variation in predictor relevance is linked to the SDM set‐up. We promote the usage of a standardized benchmark dataset (MarineSPEED) for methodological SDM studies.
  相似文献   
70.
本文根据Fuzzy集理论,运用多级模型综合评判法,对巨峰系13个品种在江淮地区的经济性状表现作了评价。结果表明,江淮地区发展巨峰系葡萄,应以红伊豆三泽系红伊豆、藤稔三个早熟品种为主,还步缩小巨峰等中晚熟品种的比例。  相似文献   
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