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1.
Increasing population in the forest zone of Cameroon has led to reduction of fallow periods and to diminution of per capita cropping land area. Alley farming is a promising technology for the zone; however, its large scale adoption depends on host of factors of which an important one is tree and land tenure. For this reason, a study was conducted in 1990 to determine implication of national land legislation and customary land and tree tenure on the adoption of alley farming in the forest zone of Cameroon.Despite national laws purposing to regulate land and tree use, ownership rights to land and trees are largely determined by customary tenure rules. According to the forest zone customs, land is passed on from father to son when the father dies. Owners of inherited lands have full rights on lands and these rights are rarely revoked. Women do not own lands but are allowed to crop any piece of their husband's land as long as they stay married. Despite the lack of land ownership, women might still readily adopt alley farming because they are primarily concerned about food crop production and the amount of land to be given to their sons in the future.Study funded by the International Livestock Center for Africa (ILCA), Addis-Abeba, Ethiopia, and technically supervised by the Land Tenure Center (LTC), University of Wisconsin, Wisconsin USA. 相似文献
2.
Woody plants diversity and possession in small-scale tree and shrub growing practices among farmers of central highland Ethiopia
were assessed by using a complete census of the trees and shrubs existing on farmers’ lands. The future prospects of diversity
and possession of woody plants in the agricultural landscapes were also investigated by using the farmers’ species preferences
and seedling demands as indicators. Comparisons were made across wealth classes, proximity clusters to a nearby state forest
and land uses. It was found that 27 tree and 21 shrub species exist on lands of the studied households. With increasing wealth
status of the households, the tree and shrub species richnesses increased. Tree and shrub species richnesses were highest
in boundary plantings and homesteads respectively. Small-scale woodlots had the highest number of tree stems while homesteads
contained the highest number of shrub stems. The number of tree stems a household possesses is strongly influenced by distance
from the state forest, family size, educational level of the household head and number of iron-roofed houses owned. And, the
shrub stems possession is significantly influenced by wealth status, distance from the state forest, land holding size, family
size, livestock holding, age of wife and possession of off-farm income sources. The species preference analysis and seedling
demand computations indicated that the woody species diversity is less likely to change in the future because there is no
difference between the currently existing species and the preferred ones. Nonetheless, the number of tree and shrub stems
on the farmers’ holdings could increase if the seedling demands of the preferred woody species are met. 相似文献
3.
以2003年和2019年剑湖保护区土地利用调查数据为基础数据,使用Excel软件进行了剑湖保护区2003年和2019年土地利用面积数据以及2003~2019年土地利用变化面积数据统计,并利用ArcGIS软件制作了2003年和2019年剑湖保护区土地利用分布图。结果表明:2003年13种土地利用类型面积从大到小的排序为乔木林地、旱地、湖泊水面、灌木林地、水田、其他林地、农村宅基地、水库水面、果园、坑塘水面、其他草地、沼泽地和采矿用地,2019年19种土地利用类型面积从大到小的排序为乔木林地、旱地、湖泊水面、灌木林地、水田、农村宅基地、水库水面、公路用地、沼泽地、其他草地、坑塘水面、果园、其他林地、河流水面、水浇地、机关团体用地、采矿用地、仓储用地和设施农用地。2006年和2019年,湖泊水面仅有分布于金华坝中的剑湖水域,沼泽地仅分布在剑湖湖滨带区域,水库水面仅有分布于山地区中的玉华水库水域,坑塘水面为仅分布于剑湖周边的鱼塘,水田、水浇地和河流水面全部分布于金华坝中剑湖的周边地区,旱地、农村宅基地和公路用地主要分布在金华坝中剑湖和山地区中玉华水库的周边区域,果园和其他林地主要分布在剑湖东面金华坝与周边山地区的过渡地段,乔木林地、灌木林地和其他草地主要分布在山地区,采矿用地仅分布在剑湖东北面靠近金华坝的山地区,机关团体用地仅有分布于剑湖环湖路外金龙河西侧的剑湖保护区管护局所在地,仓储用地仅有分布于剑湖西面环湖路外的堆矿场地,设施农用地呈现无规律分布特征。2003~2019年,呈减少的2种类型面积从大到小的排序为旱地和其他林地,呈增加的17种类型面积从大到小的排序为:灌木林地、乔木林地、公路用地、农村宅基地、沼泽地、其他草地、坑塘水面、水田、湖泊水面、河流水面、果园、水浇地、机关团体用地、采矿用地、仓储用地、水库水面和设施农用地。 相似文献
4.
5.
Ricardo Ribeiro Rodrigues Tiago Egydio Barreto Cristina Yuri Vidal 《Forest Ecology and Management》2011,261(10):1605-1613
The complex interactions among endangered ecosystems, landowners’ interests, and different models of land tenure and use, constitute an important series of challenges for those seeking to maintain and restore biodiversity and augment the flow of ecosystem services. Over the past 10 years, we have developed a data-based approach to address these challenges and to achieve medium and large-scale ecological restoration of riparian areas on private lands in the state of São Paulo, southeastern Brazil. Given varying motivations for ecological restoration, the location of riparian areas within landholdings, environmental zoning of different riparian areas, and best-practice restoration methods were developed for each situation. A total of 32 ongoing projects, covering 527,982 ha, were evaluated in large sugarcane farms and small mixed farms, and six different restoration techniques have been developed to help upscale the effort. Small mixed farms had higher portions of land requiring protection as riparian areas (13.3%), and lower forest cover of riparian areas (18.3%), than large sugarcane farms (10.0% and 36.9%, respectively for riparian areas and forest cover values). In both types of farms, forest fragments required some degree of restoration. Historical anthropogenic degradation has compromised forest ecosystem structure and functioning, despite their high-diversity of native tree and shrub species. Notably, land use patterns in riparian areas differed markedly. Large sugarcane farms had higher portions of riparian areas occupied by highly mechanized agriculture, abandoned fields, and anthropogenic wet fields created by siltation in water courses. In contrast, in small mixed crop farms, low or non-mechanized agriculture and pasturelands were predominant. Despite these differences, plantations of native tree species covering the entire area was by far the main restoration method needed both by large sugarcane farms (76.0%) and small mixed farms (92.4%), in view of the low resilience of target sites, reduced forest cover, and high fragmentation, all of which limit the potential for autogenic restoration. We propose that plantations should be carried out with a high-diversity of native species in order to create biologically viable restored forests, and to assist long-term biodiversity persistence at the landscape scale. Finally, we propose strategies to integrate the political, socio-economic and methodological aspects needed to upscale restoration efforts in tropical forest regions throughout Latin America and elsewhere. 相似文献
6.
The potential of the dry zone agro-ecosystem of southern Honduras to contribute to the conservation of Mesoamerican dry forest
tree diversity is evaluated. Four rural communities containing eight land uses were surveyed using rapid botanical sampling
resulting in the identification of 241 tree and shrub species. As a result of ordination analysis, it is concluded that the
land uses are relatively similar in their species composition, particularly maize fields (milpas), fallows, pastures and woodlots, because of the predominance of natural regeneration. Therefore all land uses might contribute
to local tree diversity conservation. Those land uses in which planting also contributes to diversity, home gardens (solares) and orchards, are more distinct; however the tree species found there are widespread and often exotics and thus not the usual
focus of conservation measures. Across the landscape the total complement of species considered a global priority for biodiversity
conservation is very low and therefore this agro-ecosystem does not represent a good place in which to implement dry forest
tree diversity conservation programmes. Instead its value is likely to be in the contribution that tree diversity makes to
rural livelihoods. Particular consideration is given to Swietenia humilis Zucc. (small leaved mahogany) and its status as a threatened species is questioned because of its abundance within this landscape
and its wide distribution.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
小陇山不同灌木林地改造模式林分树种多样性研究 总被引：2，自引：0，他引：2
生物多样性研究已经成为生态学研究的热点,而维持物种多样性是目前森林经营研究的一个主要内容。本文运用点抽样方法研究了甘肃小陇山5种不同的灌木林地改造模式的树种多样性。结果表明:带状割灌改造模式林分的树种较全面清理割灌模式丰富,Shannon-Wiener指数与Margalef指数较高,林分的树种多样性较高,林分内各树种分配较为均匀,带状割灌改造更有利于提高林分的树种多样性;在3种全面清理割灌改造模式中,改造日本落叶松模式虽然树种数与其它2种相同,但林分内树种分配均匀性差,集中性高。不同的改造模式对林分树种多样性的影响不同,这对提高和保持改造林分的物种多样性具有一定借鉴意义。 相似文献
8.
【目的】为了更好地利用半干旱黄土丘陵区的土地资源,促进该区域植被恢复,提高生物多样性,使区域生态环境有所改善。【方法】以半干旱黄土丘陵区龙滩流域的植被为研究对象,对该流域11种典型的土地利用类型(2种农地、自然荒草地、人工牧草地、撂荒草地、灌木林地、5种乔木林地)的植被物种组成和多样性进行了调查研究。【结果】流域内共调查到种子植物56科166属254种,其中裸子植物门3科7属13种,占流域总科、总属、总种的5.36%、4.22%、5.12%;被子植物门53科159属241种,占流域总科、总属、总种的94.64%、98.78%、94.88%。在被子植物门中,双子叶植物纲有50科134属205种,单子叶植物纲有3科25属36种,两纲物种分别占流域总种数的80.71%和14.17%,占该门物种总种数的85.06%和14.94%。不同土地利用类型植被多样性分析结果表明,物种丰富度表现为农地物种丰富度低,人工牧草地、撂荒草地和灌木柠条林地居中,乔木林地(山杏、山毛桃、油松、侧柏、青杨)和天然荒草地高;物种多样性表现为马铃薯农地的物种多样性低,覆膜农地、人工牧草地、撂荒草地及灌木柠条林地居中,自然荒草地和乔木林地比较高;物种均匀度表现为农地、撂荒草地、人工牧草地及灌木柠条林地的均匀度高,自然荒草地居中,乔木林地低。【结论】不同土地利用方式和植被演替恢复时间差异是产生植被多样性差异的基础,也是该区域植被恢复和物种多样性保护需要考虑的重要要素。 相似文献
9.
The highest deforestation and forest degradation rates in Africa occur in the dry forests and woodlands where pressure for land is increasing, poverty is rampant, livelihood options are few and climate change effects are severe. This paper examines factors that cause land and forest degradation in the Sahel and dry forests and woodlands of eastern and southern Africa and highlights some successful restoration practices, technologies and approaches. In the Sahel, enclosures are used to protect young growing trees while in East Africa enclosures are implemented on degraded land as a mechanism for environmental rehabilitation with a clear biophysical impact. The choice of techniques for rehabilitating specific degraded areas depends first on the priorities and management objectives of stakeholders followed by the costs and benefits associated with available rehabilitation techniques and the economic, social, and environmental values of the land resources in their current and desired future states. In the Sahel, sustainable land management is considered to be an imperative for their sustainable development and the practices include soil and water conservation activities and structures. In all regions, natural forest rehabilitation has used both natural and assisted regeneration to promote the growth of especially indigenous species through coppice regrowth and root suckers rather than seeds. Assisted regeneration was especially prevalent in the Sahel where indigenous tree species have been identified to dominate the degraded sites during early stages of secondary forest succession. The success of any rehabilitation activities depends on community-based natural resources management. In addition, the forest policies and their related policies need to be enabling in order to address issues of concern, including (1) the full participation of communities, (2) clear land and tree tenure and (3) equitable benefit sharing. 相似文献
10.
Martina M. Backes 《Agroforestry Systems》2001,50(2):119-132
In order to precisely assess the role of agroforestry for the conservation of (agro-)biological diversity there is a need
to adjust sampling methods used in plant sociology. This study is on the contribution of agroforestry land use to the in-situ conservation of indigenous trees within a typical East-African smallholder farming system in Western Kenya. A modified approach
to measuring species richness and abundance is presented. The selection of tree-rich structures was done according to management
patterns rather than considering syntaxonomic classifications from the vegetation science point of view. This approach, which
is better suited to the strongly human-influenced vegetation of agroecosystems, employs between-management unit diversity
measures to help evaluate abundance and constancy of species in particular management units.
The predominant off-farm vegetation patterns are riverine forests, rocky hillsides, hedgerows, wooded grassland relicts, woodlands or colline forest
relicts and tree groves whereas the noticeable tree-rich on-farm management units are homegardens, homesteads, life fences, coffee- and banana-groves and annual cropping fields. 98% out
of all indigenous tree species known from Bungoma, occur in off-farm lands. 53% of the indigenous tree species occur in tree rich on-farm management units while 47% of the indigenous trees are dependent on the maintenance of off-farm lands. Hedgerows embody the most promising secondary vegetation structure that shows ample potential to accommodate a wide
range of indigenous perennial species outside the natural vegetation formations. The pattern of distribution of various vegetation
structures, and the mixture with diverse tree-based on-farm plots are interesting features in regard to floristic and eco-diversity on a landscape level. In this respect, three areas
that show different population densities and distinct agro-historical conditions were compared. In regions of particular high
population density the degree of association of various functional land use forms and woodland structures – each characterised
by its own floristic make-up – is comparatively high. In contrast, in regions with less population but that were settled at
a later date, one encounters fewer stands of woody plants with lower numbers of species.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
Farm and Village Forest Use Practice in Ekiti State: Analysis of Government Policy and Tenure Issues
Joshua Kayode 《Journal of Sustainable Forestry》2013,32(4):321-328
This study analyzed the influence of government policy and tenure issues on farm and village forest use practices in Ekiti State, Nigeria. Three rural communities that were still far from urban influence were selected from each of the 16 local government areas of the state. In each community, 20 household heads were selected and interviewed with the aid of a semi-structured matrix. The interviews aimed at the determination of respondents' socioeconomic status, awareness and belief in the effectiveness or otherwise of the forest laws and regulations, land use, tenure and property rights. Results obtained revealed that the awareness of forest laws and regulations cut across the socio-economic categories. Most of these laws and regulations that were considered to be necessary could also constitute disincentives to sustainable forest development. Three types of land tenure niches—private holdings, commons, and government reserves—exist in the state. These led to land fragmentations in which individuals are now left with small holdings. Individuals with small and medium landholdings found it difficult to invest in tree planting; hence, they meet their subsistence use of wood and non-wood forest products from diverse sources. Individuals with large landholdings were found cultivating cash tree crops; timber species were not cultivated though their wildlings were preserved. Also, when land is let or leased out, tenants were not allowed to invest in tree planting on such land. 相似文献
12.
Luke C. N. Anglaaere Joseph Cobbina Fergus L. Sinclair Morag A. McDonald 《Agroforestry Systems》2011,81(3):249-265
Traditionally, most cocoa farms are established by removing the forest understorey and thinning the forest canopy so that
cocoa seedlings can grow into productive trees by utilising the forest rent of the newly cleared area and the shade provided
by the remaining trees. With the introduction of new hybrid cocoa varieties, there is a gradual shift towards the elimination
of shade trees in the cocoa landscape. Farmers have found it necessary to eliminate forest tree species to effect high performance
of these new varieties and as a result large areas of forested land are being lost, thereby posing a threat to biodiversity
A study was carried out in Atwima, a major cocoa farming district in the Ashanti region of Ghana, to assess the impact of
cocoa cultivation on tree diversity. The study also investigated farmers’ preferences for tree species retained on cocoa farms
as well as their traditional knowledge on tree species and their effect on cocoa cultivation. The assessment consisted of
identification and enumeration of all tree species with diameter at breast height greater than or equal to 10 cm, and was
carried out on one-hectare plots of: (a) Active Cocoa Farms (ACF), stratified into (i) Mature Cocoa Forest (MCF) and (ii)
Young Replanted Cocoa (YRC); (b) Fallow land (FL), and (c) Natural Forest (NF). A total of four one-hectare plots replicated
five times (or 20 ha) were enumerated. Tree diversity was more strongly influenced by landuse type than age of cocoa farm.
Fallow lands contained a higher tree diversity followed by natural forest, with the active cocoa farms, both mature and young,
containing the lowest variety of species. However, stem count was highest in the natural forest followed by FL and ACF. Generally,
stem counts of important tree species, as well as those classified as either endangered or vulnerable, were extremely low
in the landscape (0–2 per hectare), indicating a critical potential for conservation and rejuvenation. Farmers’ preference
for trees on cocoa farms was based on their usefulness. Three categories of trees emerged from their classification of trees
on cocoa farms: (i) naturally occurring trees that are very useful; (ii) naturally occurring species of minor economic use;
and (iii) naturally occurring tree species that are aggressive or incompatible with cocoa. Multistrata cocoa farms are a potential
niche for conservation, but given the current trends in cocoa replanting, future conservation strategies will have to focus
on identified targeted species which are of conservation concern, as well as those that are of value to farmers. 相似文献
13.
Land tenure and farm management efficiency: The case of smallholder rubber production in customary land areas of Sumatra 总被引：3，自引：1，他引：3
This study assesses the impact of land tenure institutions on the efficiency of farm management based on a case study of rubber
production in customary land areas of Sumatra, Indonesia. Using the modes of land acquisition as measures of land tenure institutions,
we estimated tree planting, revenue, income, and short-run profit functions, and internal rates of return to tree planting
on smallholder rubber fields. We find generally insignificant differences in the incidence of tree planting and management
efficiency (defined as residual profits) of rubber production between newly emerging private ownership and customary ownership.
This is consistent with our hypothesis that tree planting confers stronger individual rights, if land rights are initially
weak (as in the case of family land under customary land tenure systems). On the other hand, short-term profits are higher
on land that is rented through share tenancy. This result indicates that rubber trees are over-exploited under renting arrangements
due partly to the short-run nature of the land tenancy contracts and partly to the difficulty landowners face in supervising
tapping activities of tenants in spatially dispersed rubber fields.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
哀牢山植物多样性垂直分布格局 总被引：2，自引：0，他引：2
以设于哀牢山各植物群的样地调查材料为依据,分析了哀牢山东、西坡不同海拔高度地带性植物群落乔木层林木的高、径垂直分布特征,植物群落生物多样性指数的垂直分布态势。结果表明:该山地植物群落乔木层和灌木层的植物物种多样性沿海拔梯度呈单峰型分布格局,以中山湿性常绿阔叶林乔木层林木的最大和平均树高、最大胸径值和物种多样性指数最大;而灌木层植物物种多样性指数最大值出现在中山湿性常绿阔叶林带下的季风常绿阔叶林和半湿性常绿阔叶林带内;而草本层植物的物种多样性指数则沿海拔梯度上升呈整体减小的趋势;累加其植物群落乔、灌、草3层植物的物种多样性指数,哀牢山东、西坡植物群落的Shannon-Weiner指数和物种丰富度最大值出现在海拔高度2000 m左右。在相同海拔高度处,西坡植物群落的植物物种多样性高于东坡,季风常绿阔叶林的物种多样性大于半湿性常绿阔叶林,而山顶苔藓矮林的植物物种多样性最小。 相似文献
15.
于2017年5-8月对雷公山、高黎贡山和星斗山3个不同纬度自然保护区的秃杉Taiwania flousiana群落分别设20 m×50 m样地1个进行对比研究,探讨其动态规律。结果表明,3个保护区的秃杉群落中维管植物共有77科148属243种,其中雷公山的秃杉种群(重要值为0.363 5)占主要优势,其次是高黎贡山,星斗山的秃杉种群处于劣势;多样性优势度(d)指数和丰富度指数(d Ma)在乔木层为雷公山大于高黎贡山和星斗山,物种多样性指数(Dr,He’和H2’)在乔、灌、草的排序均为:雷公山>高黎贡山>星斗山,3个保护区的秃杉群落均匀度指数(Je)相差不大,都在0.70~0.95之间。根据吴征镒的中国种子植物属的分布区类型进行进行植物区系分析,3个保护区的秃杉群落的植物区系复杂,划分为24个类型,分布特点以热带分布属为主,温带分布属为辅,世界分布属最少;中国特有2属。 相似文献
16.
W. Bonou R. Gll Kakaï A.E. Assogbadjo H.N. Fonton B. Sinsin 《Forest Ecology and Management》2009,258(7):1084-1092
A study was carried out in the Lama forest reserve of Benin to characterize the habitat of Afzelia africana Sm., an endangered multipurpose tree species (found in African humid, dry forests and woodlands), in order to define a sustainable management strategy for its conservation. An estimation of species density was done on 100 square plots of 1 ha each, while tree height and dbh of all the species were measured on subplots of 50 m × 30 m within the 1 ha plots. The regenerations of A. africana (dbh < 10 cm) were counted in the diagonal quadrats of the principal plots. Presence–absence data of the species was subjected to multidimensional scaling and results showed four vegetation communities including: young fallow, old fallow, typical dense forest and degraded dense forest. Significant differences were noted between the four communities with respect to dendrometric parameters of the species. High values of these parameters were noted for the species in typical dense forest (5.2 stems/ha, 66.7 cm, 17.9 m, 7.9 m2/ha and 38.8% for the tree-density, the mean diameter, the mean height, basal area and basal area contribution of the species, respectively) whereas the lowest values were obtained for the old preforest fallow as far as the mean diameter (59.7 cm), the mean height (15.7 m) and the basal area contribution (27.7%) of the species were concerned. In general, the basal area of A. africana in the over vegetation types was less than 3 m2/ha. No A. africana tree was found in the young preforest fallow while more than 80% of A. africana trees were found in the typical dense forest community. Stem diameter and height structures of the species in all the four communities showed a left dissymmetric Gaussian shape and were well adjusted to Weibull distribution. 相似文献
17.
Diane Saint-Laurent Jean-Sébastien Berthelot Vernhar Gervais-Beaulac 《Agroforestry Systems》2018,92(6):1517-1534
A number of forests in agroforestry environments are at risk due to urban development or agricultural expansion. These forests often consist of patches of wooded areas scattered in the agricultural and urban grid, and often constitute green corridors that enable a flow between animal and plant species (migration corridors). This study evaluates the composition and structure of riparian forests in agroforestry areas that are subject to various natural and anthropogenic disturbances. This study aims to understand the dynamics of these riparian forest populations and evaluate the effects of the disturbances on the tree stands (e.g. floods, partial cutting), while taking into account their development over space and time based on a diachronic assessment from 1945 to 2010. Although these woodlands are subject to various disturbances, a fairly large diversity of tree species can be noted, and the regeneration of the saplings and small trees follows a normal growth curve (asymmetric) with a high contingency of young tree population comparable to a typical reverse-J distribution. However, lower densities are observed for riparian stands subject to frequent flooding, which could over time compromise recruitment and forest regeneration for some tree species (e.g. woody plants with weak adaptive strategies). The multivariate analyses (Redundancy Analysis and Canonical Correspondence Analysis) conducted over all the soil, environmental and forest data reveal that some variables are more strongly related to the composition of the forest populations, including pH, ground litter and soil drainage. However, these variables must still be considered as being part of a set of interacting soil conditions. Lastly, the future of these woodlands may appear uncertain because there are no government policies or measures to ensure their protection and preservation. 相似文献
18.
《Forest Ecology and Management》2004,190(1):15-31
The quantitative liana inventories made in five peninsular Indian independent forest sites, distributed in the Western Ghats, Eastern Ghats and on the Coromandel coast, were examined particularly with reference to site altitude and forest stature. Liana diversity totaled 148 species in 101 genera of 47 families, in a total sample of 47 ha. The coefficient of variability in species distribution among the five sites was used to identify an oligarchy in liana species by taking 55 abundant species from the species pool. Ordination analysis, based on presence–absence as well as relative density of liana species indicated a geographical differentiation among the five sites in both the ordinations with respect to site altitude. Liana density (stems>1.6 cm diameter) decreased with increasing altitude, whereas richness was highest at intermediate elevations. The mean liana density across the forest sites showed a weak negative correlation with forest stature. The lianas encountered in the five study sites fell under six climber types, of which twining was the chief climbing mechanism, both in terms of species diversity and density, and tendril climbers were more abundant in dry evergreen forests than in the wet evergreen forests. In liana diaspore dispersal modes, the majority of evergreen forest species possessed animal dispersal guilds, whereas wind-dispersal was prevalent in semi-evergreen and dry evergreen forests. 相似文献
19.
东莞大岭山村边自然次生林群落物种组成特征及其对区域物种库的贡献 总被引：9，自引：2，他引：7
对东莞大岭山村边自然次生林（俗称“风水林”）调查表明,群落组成种类复杂并富于热带性,1hm^2样地内共有维管束植物111种,隶属56科89属,其中以木本植物占绝对优势,有67种,占60．36％;群落中种子植物属为热带分布的共有74属,占总属数的92．5％。群落乔木可分三层,以越南山龙眼为主,其在各层的重要值分别为117．12％,129．44％和57．41％;灌木层以罗伞树和九节等为主;草本层植物以乔灌木小苗为主,草本植物仅沿阶草、海芋和半边旗等少数种类。群落木本植物的科、属、种对区域物种库的贡献率较大,分别为37．7％,25．6％和22．5％,以藤本植物的贡献率最高,接近50％,乔灌植物的贡献率也在20％左右．与鼎湖山季风常绿阔叶林比较．两者物种组成结构相似．但组成种娄仍有一定差距． 相似文献
20.
The tree species diversity, groundvegetation species richness, and soilcharacteristics were studied forEucalyptus camaldulensis woodlots and thenatural miombo woodlands in the Mukarakate Areaof Northeastern Zimbabwe. The woodlandcharacteristics were measured and soil sampleswere taken at a total of thirty-four miombowoodland plots and twenty-seven eucalyptusplantations.The number of tree species was significantlyhigher for the miombo woodland sites than forthe eucalyptus woodlots. The Berger-Parker andShannon-Wiener Index values for speciesdiversity were higher for the tree speciesfound on the miombo woodland sites. There wereno significant differences between theeucalyptus woodlots and the miombo woodlands inthe percentage of grass cover and the number ofgrass and herb species. The same grass and herbspecies were common in both the woodlots andthe woodlands. The older woodlots hadsignificantly more tree and herb species thanthe younger woodlots.Soil nutrient analyses showed no significantdifferences between the woodlots and thewoodlands regarding their available phosphorusand total nitrogen, but the total phosphorusand total carbon were higher for the miombowoodlands. The results suggest that E.camaldulensis woodlots established in areasthat were formerly fields and grazing areas inthe savannah-like conditions pertaining inSouthern Africa do not cause the loss ofspecies richness or soil nutrients. In heavilydeforested areas eucalyptus woodlots may evencontribute positively to the protection andpreservation of indigenous trees species andother flora. 相似文献