刈割和封育对松嫩草原碱化羊草草地土壤跳虫群落的影响

应用类群数、个体密度和多样性指数等多个群落参数,研究刈割活动和围栏封育对松嫩草原碱化羊草草地土壤跳虫群落特征的影响.本研究共捕获土壤跳虫1 086只,分别隶属于8科18属.研究结果表明,围栏封育能够提高草地土壤跳虫的类群数、个体密度和多样性,其中个体密度提高最为迅速和显著;但长期刈割活动造成恶化的土壤理化环境对跳虫类群数量增长和群落食物网的复杂性与稳定性的提高制约是长期的;凋落物的存在与否对草地土壤跳虫群落有较大的影响,其中凋落物的累积有助于退化草地土壤跳虫群落的恢复,而凋落物的流失可能会使草地土壤跳虫群落进一步退化.     

围栏封育对草地土壤养分改良效果的研究进展

围栏封育是目前较为普遍的一种退化草地恢复措施,不仅有利于植被的恢复,也有利于土壤养分的改善。本文综述了了国内近年有关围栏封育对草地土壤有机质、氮、磷和钾含量影响的相关研究成果,归纳概括了影响封育改良土壤养分含量的因素,指出了今后的研究方向,为我国退化草地封育效益合理性研究和指导草地利用提供一定的基础资料和科学依据。     

围栏封育对半干旱区植物群落稳定性的影响

以宁夏回族自治区盐池县柳杨堡人工封育区植被为研究对象,利用法国生态学专家Godron提出的方法测定植被稳定性.结果表明:研究区的5个样地(核心区、边缘区、外围区、新翻区和对照区)植物群落的稳定比分别为38/62、34/66、34/66、41/59和36/64,与稳定点20/80均有很大差距,表明柳杨堡封育区的植被群落不...     

干旱荒漠区封育沙地植被群落特征变化研究

以天然植被围栏封育和人工种植+围栏封育措施下沙地植物群落为对象,以无封护的流动沙地做对照,研究了不同恢复措施对沙地群落物种组成及结构变化的影响.结果表明,(1)封育15 a后,人工种植+围栏封育区侵入物种的丰富度随演替的进展已达12种,其中猪毛菜7.562株/m~2,碟果虫实3.233株/m~2,雾冰藜3.017株/m~2,沙米1.615株/m~2,狗尾草1.112株/m~2.种类组成及生活型结构在向天然植被围栏封育区植物群落靠近,但两者间仍表现出较大差异.(2)在类型组成上,两种封育措施区差异主要表现在优势科及各科种类数量上.(3)在综合多样性特征上,两种措施区草被层的Shannon指数和丰富度指数存在显著差异,而其余各指数两者差异均不显著,但天然植被围栏封育区灌木层的生态优势度指数较高.(4)群落的相似性指数表明,两种封育措施间的植物群落差距较大,且2种封育措施下的植物群落与植被呈零星状分布的无封护措施的流动沙地相比,生态差距均十分显著,这表明封育可明显促进沙地植被的多样性恢复,其中人工种植对沙地植物群落物种多样性恢复的作用是相对缓慢而渐进的.     

黄土区封育和放牧草地物种多样性和地上生物量对氮素添加的响应

氮素添加对草地生态系统地上生物量具有普遍促进作用,但对解释引起物种多样性丧失的机制仍存在较大争议。本研究以黄土高原半干旱区长期封育和连续放牧草地为对象,通过设置不同氮素添加水平来探索两种典型的草地管理方式下群落地上生物量、物种多样性、群落组分结构对氮素添加的响应及其异同以及物种多样性与地上生物量的关系,并研究这些响应的潜在生态学机制。结果显示,1)氮素添加显著提高长期封育草地地上生物量的同时降低了物种多样性;放牧草地群落地上生物量、物种多样性对氮素添加的响应与封育草地相同,但其响应程度均小于封育施肥草地;2)草地群落物种多样性随地表凋落物生物量增加而降低,随植被透光率增加而升高; 3)封育施肥草地Shannon-Wiener多样性指数与地上生物量存在显著线性负相关关系,而放牧施肥草地的物种多样性与地上生物量不存在显著的相关关系。以上结果表明放牧能够减缓施肥对物种多样性的负效应,在轻微降低物种多样性的前提下显著提高群落地上生物量,是一种合理的草地管理方式。     

农牧交错带不同封育时间对植物特征值及多样性的影响

为研究我国北方农牧交错带不同封育时间对干旱、半干旱草原植物特征值及多样性的影响,同时探索农牧交错带草原封育周期,本研究选取位于我国农牧交错带的宁夏盐池人工封育草原为研究对象,采用样方调查法,于每年7-8月份(植物生长季节)对封育区植被生长状况进行调查,调查内容包括:植物名称、植物种数、株数、盖度、高度、地上生物量(鲜重)等。运用生态学、地统计学原理,结合Biodiversity Pro、Microcal Origin等生态学统计软件对外业数据进行处理、分析,结果表明:封育2-3年后植物群落优势种优势地位得到巩固,而一些伴生种则在竞争中消失;封育区植物特征值在封育2-3年后达到最大,如地上生物量(鲜重)在封育3年达到最大值,为6907.75kg/hm2,此后呈下降趋势;封育区主要植物重要值及植物物种多样性均在封育2-3年后出现最大值,此后也不同程度地呈下降趋势。     

封育条件下白茅繁殖对策研究

在对云南马龙县退化山地草甸围栏封育恢复过程中,白茅Imperata cylindrical是草地中优势植物,在整个群落的演替过程中有着重要影响。因此,对封育条件下白茅的无性繁殖器官根茎特征变化进行研究具有非常重要的意义。研究结果表明：封育使3个退化梯度形成了3个不同的生态系统群落。在轻度退化封育区,白茅的根茎随封育时间的延长而变长,分蘖枝数无明显变化,但枝条密度随封育时间的延长而逐年增加,封育促进了该区白茅无性繁殖。在中度和重度退化封育区,白茅的根茎随封育时间的延长而变短、变细,重度退化封育区变化差异极显著（P＜0.01）,中度退化封育区变化差异显著（P＜0.05）,分蘖枝数减少,封育使白茅无性繁殖在中度和重度退化区受到抑制。     

草地利用和管理方式对地木耳生物量的影响

地木耳(Nostoc commune)是一种固氮蓝藻,其固氮活性是可逆的,在天然草地氮素循环中起着非常重要的作用。本研究分析了放牧、刈割、烧荒以及围封对地木耳生长动态的影响,以期为合理利用和管理天然草地提供理论依据。结果表明,围栏封育样地地木耳的生物量最高,适度放牧和刈割样地次之,重度放牧显著抑制了地木耳生长,其总生物量仅相当于围栏封育的11.2%～35.1%;烧荒处理当年地木耳生长受到抑制,但随着凋落物的积累,其生长量逐渐增加;地木耳生物量与凋落物、立枯物的量呈显著正相关（P<0.05）,凋落物和立枯物的量是影响地木耳生长的主要因素。因此,适度放牧和围栏封育有利于草地固氮蓝藻--地木耳的生长和增加草地氮素供应。     

Effectiveness of electro-fencing for restricting the ranging behaviour of wildlife: a case study in the degazetted parts of Akagera National Park

Several national parks on the African continent have been fenced to mitigate human–wildlife conflict, but the effectiveness of different fencing strategies seems to vary between regions. Here, we assessed the effectiveness of electro-fencing for restricting movement patterns of several wild ungulates in Akagera National Park (NP), Rwanda. Following the turmoil of the Rwandan genocide and civil war (1991–1995), large numbers of returning war refugees brought about an increasing pressure on land use, after which considerable parts of the western Akagera NP and adjacent Mutara Game Reserve were degazetted, followed by the construction of an electric fence in 2013 and a helicopter-based game-drive of ungulates into the modern park. We conducted distance sampling of wildlife and domestic livestock in the Uruhita plain – now no longer part of Akagera NP but bordering the modern Akagera NP to the west – for extended periods of time (2010–2015) before and after fencing. For abundant species population densities could be calculated, whereas for other species encounter frequencies are reported. We report on continuously high cattle densities, and increasing encounter frequencies of sheep/goats in the Uruhita plain. We found decreasing densities of zebra (Equus quagga) and decreasing encounter frequencies of waterbuck (Kobus ellipsiprymnus), stagnant encounter frequencies in the case of topi (Damaliscus lunatus jimela) and stagnant densities of impala (Aepyceros melampus). The latter species can jump fences, and we argue that competitive release and reduced predation may be the prime factors leading impala to (temporarily) exploit grasslands outside the modern national park.     

Agroforestry and soil conservation needs of smallholders in Southern Zambia

An agroforestry and soil conservation needs assessment survey conducted in southern Zambia revealed valuable insight into needs, constraints and development options as perceived by smallholders themselves. Inadequate efforts to conserve soil are due to technical and socio-economic factors, they do not result from a lack of awareness of the widespread erosion threat. Fruit tree planting, windbreak establishment as well as the protection of the natural Faidherbia albida regeneration in cropland are popular agroforestry interventions whose positive effects are widely acknowledged. Forty-two perennial species were found to directly contribute to people's diet. Although local fuelwood and fodder shortages as well as the need for fencing are recognized only few respondents envisage agroforestry solutions such as fuelwood and fodder tree planting or live fencing. Most smallholders are interested in tree planting but have so far only planted few trees. Those planted are usually exotic fruit trees. Drought hardly, termite and browse resistant perennials adapted to smallholder tree planting must be provided by the extension services. The widespread exclusion of women from decision making and the lack of tenure security hampers female participation in agroforestry development and consequently threatens sustainable development altogether.