樟子松固沙林带间植被恢复及其对林草界面作用的响应   总被引：1，自引：0，他引：1  

姜丽娜  杨文斌  姚云峰  卢琦  杜敏  王琳琳 《中国沙漠》2011,31(2):372-378

调查了海拉尔市巴音岱林场不同分布格局、不同带间距的人工樟子松林带内植被恢复过程及物种多样性的差异,分析了林草界面生态学效应,研究了林草界面对带间植被自然恢复的作用。结果表明,宽的带间距带内物种多样性和生物量变化曲线出现了两个高峰,而窄的带间距带内只有一个高峰,说明该地区林带之间距离不应小于12 m;当林带之间距离为16~28 m时草本物种多样性出现最大值。植被恢复效果表现为带间距12 m差于带间距24 m,虽然都差于天然植被,但边际效应大大地加速了群落演替的进程。研究区樟子松林草界面边缘效应影响域为20 m, 其小尺度范围内生境异质性也很明显。行带式造林带间距离不应大于40 m,超出边缘效应影响域不利于带间植被恢复。  相似文献   

Response of regeneration diversity of <Emphasis Type="Italic">Carex Lasiocarpa</Emphasis> community to different water levels in Sanjiang Plain,China     

Li Wang  Changchun Song  Jinming Hu  Tao Yang 《中国地理科学(英文版)》2010,20(1):37-42

The species diversity at the regeneration stage, inflenced by different water levels, is important for community composition in the later growing season. Regeneration diversity of Carex lasiocarpa community under different water levels was studied at two stages, recruitment and adult, in the Sanjiang Plain, Heilongjiang Province, China. The results showed that, at the two growing stages, important value of C. lasiocarpa population and species richness of the community decreased with the increasing water level, while the Simpson and Shannon-Wiener diversity indexes and Pielou evenness index increased. Under different water levels, community diversities were higher at the recruitment stage, while population important values of C. lasiocarpa were higher at the adult stage. Indexes in vegetation evaluation must be chosen prudentially for successful restoration and effective management of wetlands, and especially for wetland restoration, the optimal time should be selected according to the restoration objectives and costs.  相似文献   

2007-2008年云南高原湖泊鱼类多样性与资源现状   总被引：1，自引：0，他引：1  

袁刚  茹辉军  刘学勤 《湖泊科学》2010,22(6):837-841

为了解云南高原湖泊鱼类资源及多样性现状,于2007-2008年对云南高原11个大型湖泊进行了2次调查.共鉴定鱼类39种,隶属于7目13科33属,鲤形目鱼类最多,占65.0%.其中共调查到土著鱼类14种,外来鱼类25种.在种数上,外来鱼类已经成为各湖泊的主体.在鱼类区系上,由高原鱼类区系向长江中下游鱼类区系演变.主要经济鱼类年龄结构以0+和1+鱼为主.分析表明,土著鱼类多样性与海拔和湖泊面积密切相关.土著鱼类物种数在中等海拔(1700-1800m)处最高,并与湖泊面积呈显著正相关.最后根据调查结果,提出了一些保护建议.  相似文献   

Six decades of agricultural land use change in Bangladesh: Effects on crop diversity,productivity, food availability and the environment, 1948–2006     

Sanzidur Rahman 《Singapore journal of tropical geography》2010,31(2):254-269

This paper provides a detailed analysis of agricultural land use change in Bangladesh over a 59‐year period (1948–2006) and examines how these have impacted crop diversity, productivity, food availability and the environment. The key findings of the analysis are: first, land use intensity has increased significantly over this period, mainly from the widespread adoption of a rice‐based Green Revolution technology package beginning in the early 1960s; second, contrary to expectation, crop diversity too has increased; third, although land productivity has increased significantly, declines in the productivity of fertilizers and pesticides raise doubts over sustaining agricultural growth; fourth, food availability has improved, with a reversal in the dietary energy imbalance in recent years despite a high population growth rate; and finally, the production environment has suffered with widespread soil nutrient depletion experienced in many agroecological regions. The policy implication points towards crop diversification as a desired strategy for agricultural growth to improve resource economy, productivity and efficiency in farming in Bangladesh.  相似文献   

广东肇庆西江珍稀鱼类省级自然保护区鱼类多样性   总被引：10，自引：4，他引：6  

李捷  李新辉  谭细畅  李跃飞  何美峰  罗建仁  林建志  苏少芳 《湖泊科学》2009,21(4):556-562

2006-2008年对西江珍稀鱼类自然保护区江段进行鱼类组成与生境调查,共采集鱼类81种,隶属于11且25科69属.其中洄游鱼类8种,外来种6种,土著淡水鱼类67种.以种类数及其多样性指数分析,表明西江保护区鱼类种类多样性较高.优势种是鲮鱼、赤眼鳟、广东鲂,主要经济鱼类为广东鲂、赤眼鳟、鲮鱼、黄尾鲴、花鰶,珍稀濒危物种有花鳗鲡.珠江长臀鮠、台细鳊及多种珠江水系特有鱼类.保护区鱼类生态类型多样,以定居性、杂食性和底栖鱼类为主.保护区江段水文动力条件独特,河床底质结构复杂,是西江鱼类栖息、产卵的理想场所,栖息地破坏、过度捕捞等是保护区鱼类生物多样性的主要胁迫因素.  相似文献   

Mountain pastures, environmental degradation, and landscape remediation: The example of a Mediterranean policy initiative     

T. Lasanta  J. Arnez  M.P. Errea  L. Ortigosa  P. Ruiz-Flao 《Applied geography (Sevenoaks, England)》2009,29(3):308-319

Since the 1950s the Spanish Mediterranean mountains have undergone a process of population decline, abandonment of land by farmers, and a reduction in livestock pressure. These changes have involved pasture loss as a result of the spread of scrub and an increase in the incidence of fires. To avoid these negative outcomes the regional administration of La Rioja (Spain) has implemented scrub clearance programs. Between 1986 and 2005 a total of 23,668 ha were cleared, particularly on abandoned fields where the processes of vegetation succession had led to the dominance of Genista scorpius and Cistus laurifolius. Pasture regeneration as a result of scrub clearing of areas dominated by G. scorpius has resulted in a productivity rise from 6666 to 12,983 Mj/ha/year, whereas productivity of areas dominated by C. laurifolius has risen from 2435 to 9741 Mj/ha/year. The clearing of scrub needs to be recognized as a significant factor contributing to the control of fire. Scrub clearing has had positive results in La Rioja, leading to a reduced incidence of fires in recent years. Between 1996 and 2005 only 155 ha/year was burnt, compared with 1541 ha/year over the period from 1976 to 1985. Scrub clearing appears to be an appropriate means of management in marginal mountainous areas without the need for large investments of time and money.  相似文献   

茂兰喀斯特森林林隙物种多样性的动态规律   总被引：5，自引：0，他引：5  

龙翠玲 《山地学报》2009,27(3)

分析了茂兰喀斯特森林不同大小和发育阶段林隙物种多样性的动态变化规律。结果表明：林隙中乔木、灌木、草本和藤本植物的多样性指数H′在140～210 m2时最大,随林隙面积的进一步扩大,H′呈下降趋势。乔木、灌木和草本的多样性指数H′在林隙形成的20～30 a间达最大值,随林隙年龄的增加而减小。藤本植物的多样性指数H′在林隙形成初期至40 a时逐渐增加,在40 a时达最大值,最大值出现时间较其他生长型滞后。各生长型物种丰富度指数R1和均匀度指数J的变化趋势总体上与物种多样性指数相一致,生态优势度λ值与物种多样性指数几乎相反。乔木和藤本植物的多样性指数随林隙大小和年龄的变化趋势较灌木和草本植物和缓,灌木和草本植物对林隙环境的时空变化最为敏感。  相似文献   

Effects of grazing and climate change on species diversity in sandy grassland, Inner Mongolia, China     

HaLin Zhao  oshiya Okuro  RuiLian Zhou  YuLin Li  XiaoAn Zuo  Gang Huang 《寒旱区科学》2009,1(1):0030-0038

To understand the effects of animal grazing activities and climate change on sandy grassland vegetation in northern China, a field grazing and protected enclosure experiment was conducted from 1992 through 2006 in Horqin Sand Land, Inner Mongolia. The results showed that (1) the grazing was primary responsible for changes of the vegetation richness and diversity in the grazing grassland and that changing climate was the main reason for changes in the species richness and diversity in the grassland protected from grazing; (2) light and moderate grazing can promote restoration of the richness and the diversity in the degraded grassland, and heavy grazing could result in a decrease of the richness and diversity; (3) heavy grazing can result in significant decrease of the perennial diversity, and moderate and light grazing promotes increase of the perennial diversity; the grazing, whether heavy or moderate and light grazing, was beneficial to increase of the annual diversity; (4) heavy grazing was not beneficial to diversity of Graminean and Chenopodiaceae, and moderate and light grazing was favorable the diversity of Compositae and Chenopodiaceae; (5) the warm-humid climate was favorable to increase of the richness and the diversity, and the warm-drought climate could result in decease of the richness and the diversity; (6) increased precipitation was favorable to perennial diversity and the diversity of Graminean, Leguminosae, and Compositae, and decreased precipitation had few effects on the annual diversity and Chenopodiaceae diversity.  相似文献   

内蒙古荒漠-草原过渡带灌木群落特征     

宋兆斌  辛智鸣  朱雅娟 《中国沙漠》2022,42(2):104-112

荒漠-草原过渡带是草原逐渐被荒漠取代的区域.沿阿拉善左旗-乌拉特后旗调查灌木群落,分析植物群落的结构和物种多样性,以期为生物多样性保育提供理论依据.结果表明:该荒漠-草原过渡带有62种植物,隶属于18科、47属,禾本科、藜科、豆科和菊科的植物较多.植物主要由灌木和多年生草本构成,以旱生植物为主,主要包括红砂(Reaum...  相似文献   

基于Theil指数的广东省入境旅游经济时空差异研究     

王建军 《地域研究与开发》2012,31(1):99-103,115

运用Theil指数定量评价了1990-2009年广东省入境旅游经济时空尺度上的市际、地带间和地带内差异变化状况,其结论如下:(1)在时间尺度上,广东入境旅游经济市际差异Tp、地带内差异Twr演变呈逐渐收敛趋同的阶梯状下降趋势;珠三角地带间及地带内差异也呈阶梯状下降,东翼、西翼、山区地带间及地带内演变趋势不明显.(2)在空间尺度上,广东省入境旅游经济发展存在非均衡性,市际差异Tp主要来源于地带内差异Twr的贡献,尤其是珠三角地带内差异的贡献;珠三角与东翼、西翼、山区地带间差异较大,而东翼、西翼、山区地带间差异很小,地带间差异Tbr指数珠三角＞东翼＞山区＞西翼.引入区域分离Separation(缩写为SEP)指数来定量比较广东省四大地带入境旅游经济分离收敛的空间变化规律,并对广东省入境旅游经济发展提出相关建议.  相似文献