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1.
Impacts of artisanal gold mining systems on soil and woody vegetation in the semi‐arid environment of northern Ethiopia 
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下载免费PDF全文 Hailemariam Meaza Mushir Ali Zbelo Tesfamariam Niguse Abebe 《Singapore journal of tropical geography》2017,38(3):386-401
Gold mining is a tremendously important economic activity in rural districts of Ethiopia. We assessed the impacts of artisanal gold mining on soil and woody vegetation in northern Ethiopia. Estimation of soil loss, plant inventory, group discussions and transect studies were used to address the research questions. We employed t‐test to compare woody species and soil loss between mined and unmined sites. Moreover, we ran one‐way ANOVA to compare the average volume of soil loss among the mining sites. The study shows that gold mining removed colossal volumes of soil from the mining landscape with a significant difference among gold mining sites (P ≤ 0.05). Soil loss between the mined and unmined sites was also significant (P ≤ 0.05). Moreover, gold mining destroyed massive tracts of vegetation. Woody species encountered at plot level decreased from artisanal gold mined to unmined sites (P ≤ 0.05). Moreover, dead trees and exposed tree roots were higher in mined than the unmined areas (P ≤ 0.05). This discouraged regeneration and recruitment of woody vegetation. To conclude, gold mining system converted vegetated sites and farmlands into dysfunctional landscape. Therefore, we suggest that combined rehabilitation efforts are required to overcome the challenges of artisanal gold mining on sustainable land management in northern Ethiopia. 相似文献
2.
古尔班通古特沙漠生境对植物群落格局的影响 总被引：16，自引：0，他引：16
沿87o37'09"~88o24'04"E纵穿古尔班通古特沙漠,对44o14'04"~45o41'52"N的范围进行11个样地的地貌景观调查、植被分布参数采集和土壤取样。研究区统计到的植物种数占古尔班通古特沙漠文献资料中植物种数的1/3,出现的植物群落构建了该沙漠大面积成片分布的荒漠植被景观。调查发现,随着宏观生境的空间变化,植物群落作相应的演替。在此基础上,利用因子分析 (PCA)和相关分析 (CA) 查明了沙漠风沙土理化属性,如土壤养分、盐分、水分、碱性 (pH) 等微生境的异质性仅对沙漠植被草本层片的多样性 (PIE草) 产生显著影响。同时,这些微生境因相互拮抗使沙漠环境处于暂时的脆弱平衡之中。 相似文献
3.
This paper reports a geomorphologic landscape investigation, vegetation survey and soil sampling at 14 sites across the Gurbantunggut Desert between 87°37′09"-88°24′04"E and 44°14′04"-45°41′52′Nl. The study encountered 8 species of low trees and shrubs, 5 of perennial herbs, 8of annual plants and 48 of ephemeral and ephemeroid plants. These species of plants represent one-third of the species found in the Gurbantunggut Desert, and their communities make up a large proportion of desert vegetation with great landscape significance. In the investigation we found that the plant communities are accordingly succeeded with the spatial variation of macro-ecoenvironment.Using Principal Component Analysis (PCA) and Correlation Analysis (CA) we found that the micro-ecoenvironment heterogeneity of aeolian sandy soil′s physical and chemical properties such as soil nutrient, soil moisture, soil salt, pH etc. only impacted the diversity of herb synusia (PIEherb) of the desert, with a negative correlation. Meanwhile, the impact of microhabitat on the plant community pattern with an antagonistic interaction made vegetation′s eco-distribution in a temporary equilibrium. 相似文献
4.
QIAN Yibing WU Zhaoning ZHANG Liyun SHI Qingdong JIANG Jin TANG Lisong 《地理学报(英文版)》2004,14(4):447-455
1IntroductionStudy on the interrelationship between vegetation patterns and their habitat heterogeneity is important to recover and rehabilitate the desert vegetation, stabilize the desert ecosystem and prevent desert expansion. Domestic and foreign researchers have carried out many studies on this topic (Archer etal., 2002; Bolling etal., 2000; Chen etal., 2003; Dasti etal., 1994; Gu etal., 2002, Li etal., 2001; Li etal., 2001; Liang etal., 2003), which have used and refined statistic tech… 相似文献
5.
韩国的乡村林木处于偏远村庄附近,单独的树木或一片树林,往往构成风水因素。乡村林木也有野生动物生境的功能,有益于农业生物多样性。本文中,乡村林木分为4种类型(天然林、半天然林、半人工林、人工林)23个主要树种(优势种或次优势种)。赤松(Pinus densiflora)在50个地点是优势种,光叶榉(Zelkova serrata)在45个地点为优势种。乡村林木立地植物共分125科、519属、1081种。尽管乡村林木占地面积极小,占100 000 km2韩国国土面积的0.00278%,但这种生态系统具有重要的生物多样性和生境保护功能。乡村林木不仅是保育生物多样性的一个基础,还能为韩国提供生态系统服务。 相似文献
6.
This paper reports a geomorphologic landscape investigation, vegetation survey and soil sampling at 14 sites across the Gurbantunggut Desert between 87o37'09'-88o24'04'E and 44o14'04'-45o41'52'N. The study encountered 8 species of low trees and shrubs, 5 of perennial herbs, 8 of annual plants and 48 of ephemeral and ephemeroid plants. These species of plants represent one-third of the species found in the Gurbantunggut Desert, and their communities make up a large proportion of desert vegetation with great landscape significance. In the investigation we found that the plant communities are accordingly succeeded with the spatial variation of macro-ecoenvironment. Using Principal Component Analysis (PCA) and Correlation Analysis (CA) we found that the micro-ecoenvironment heterogeneity of aeolian sandy soil's physical and chemical properties such as soil nutrient, soil moisture, soil salt, pH etc. only impacted the diversity of herb synusia (PIEherb) of the desert, with a negative correlation. Meanwhile, the impact of microhabitat on the plant community pattern with an antagonistic interaction made vegetation's eco-distribution in a temporary equilibrium. 相似文献
7.
E. Thomas I. Vandebroek P. Van Damme P. Goetghebeur D. Douterlungne S. Sanca S. Arrazola 《Journal of Arid Environments》2009,73(9):854-861
A quantitative ethnobotanical study was conducted in the semi-arid Bolivian Andes community of Apillapampa to evaluate the impact of site accessibility on the diversity and perceived usefulness of (sub-)woody plants. Vegetation was sampled in thirty-six transects of 50 × 2 m2, whereas data on plant uses were obtained from 13 local Quechua participants. Accessibility of sample sites correlated negatively with plant diversity, but positively with perceived usefulness. Hence, in spite of being less diverse, vegetation of more accessible sites was perceived as more useful to people than vegetation of more remote and also more diverse sites. This result contributes to the validity of the widely accepted notion that “more accessible plant resources are more useful to people”, not only at the level of individual plant species, but also for entire vegetation communities. In this respect, our finding that people attribute an equal usefulness to the vegetation of two local ecological zones (i.e. prepuna and puna) most likely reflects their similar accessibility from the village centre, which is located on the edge between both zones. 相似文献
8.
Soil water deficit and vegetation restoration in the refuse dumps of the Heidaigou open-pit coal mine, Inner Mongolia, China 总被引：1，自引：0，他引：1
The sustainability of ecosystem restoration of refuse dumps in open-pit coal mines depends on plant species selection, their configuration, and the optimal usage of water resources. This study is based on field experiments in the northern refuse dump of the Heidaigou open-pit coal mine in Inner Mongolia of China established in 1995. Eight plant configurations, including trees, shrubs, grasses, and their combinations, as well as the adjacent community of natural vegetation, were selected. The succession of the revegetated plants, soil water storage, the spatiotemporal distribution of plant water deficits degree and its compensation degree were also studied. Results indicated that the vegetation cover (shrubs and herbaceous cover), richness, abundance, soil nutrients (soil organic matter, N and P), and biological soil crust coverage on the soil surface are significantly influenced by the vegetation configurations. The average soil water storage values in the shrub+grass and grass communities throughout the growing season are 208.69 mm and 206.55 mm, which are the closest to that of in the natural vegetation community (215.87 mm). Plant water deficits degree in the grass and shrub+grass communities were the lowest, but the degrees of water deficit compensation in these configuration were larger than those of the other vegetation configurations. Differences in plant water deficit degree and water compensation among the different configurations were significant (P<0.05). Plant water deficit degrees were predominantly minimal on the surface, increased with increasing soil depth, and remained stable at 80 cm soil depth. The soil moisture compensation in the natural vegetation, shrub+grass, and grass communities changed at 10%, while that in other vegetation communities changed between 20% and 40%. Overall, we conclude that the shrub+grass and grass configuration modes are the optimal vegetation restoration models in terms of ecohydrology for future ecological engineering projects. 相似文献
9.
Communal rangelands provide diverse ecosystem services to millions of pastoralists and agro-pastoralists. Resettling destitute communities into hitherto uninhabited communal rangelands and forests, a common practice throughout Sub-Saharan Africa, is a threat to the sustainable use of range and forest land resources. In order to understand the effect of resettlement on a semi-arid woodland in northwestern Ethiopia, satellite imagery of 23 resettlement villages taken over a period of fourteen years, and woody vegetation floristic data for three old resettlements, three new resettlements, two refugee camps and one protected area were analyzed using ANOVA and canonical correspondence analysis (CCA). The normalized differential vegetation index (NDVI) and canopy cover around all village types decreased with disturbance gradients, while the magnitude of change varied according to the type of settlement. Limited canopy cover was observed in refugee camps and new resettlements, compared to old resettlements and protected areas. Woody vegetation height class showed a J shaped distribution in all sites except refugee camps (RC), indicating a decline in vegetation. CCA showed that variables like site type, altitude and disturbance gradient significantly affected the diversity of woody species at the different sites. Comparison of individual species responses to disturbances indicated that low fodder value invaders like Dichrostachys cinerea, and many Acacia species were increasing in proportion and coverage at the expense of some multipurpose species including Tamarindus indica, Diospyros mespiliformis, and Pterocarpus lucens. In the absence of regulated vegetation use, resettlements result in a decline in overall vegetation cover and a shift in floristic diversity in favor of invasive species. 相似文献
10.
在半干旱沙区植物天然更新过程中,种子萌发、幼苗出土是植物种群维持和实现更新的关键阶段。通常认为,在这一阶段,土壤水分和土壤种子库是主要制约因素。分别对流动沙丘迎风坡与丘间低地过渡带的出土幼苗密度与土壤种子库密度和土壤水分进行二元相关分析。结果表明,生长季的出土幼苗密度与土壤种子库密度的相关性未达到显著水平（P>0.05）;出土幼苗密度与土壤水分呈显著正相关（P<0.05）,而且,幼苗密度随土壤水分呈对数增加。这说明,在植被入侵流动沙丘迎风坡与丘间低地过渡带裸沙的过程中,土壤水分是主要的制约因素,而土壤种子库的制约作用则没有表现出来,植被自然恢复更多地依赖于从沙丘附近植物群落传播来的种子。 相似文献
11.
J.A. Eccard W.R.J. Dean M.C. Wichmann S.M. Huttunen E. Eskelinen K.A. Moloney F. Jeltsch 《Journal of Arid Environments》2006,64(4):604-615
Recent extensive harvesting of large, often dead Acacia trees in arid savanna of southern Africa is cause for concern about the conservation status of the arid savanna and its animal community. We mapped vegetation and nests of the Black-tailed Tree Rat Thallomys nigricauda to assess the extent to which the rats depend on particular tree species and on the existence of dead, standing trees. The study was conducted in continuous Acacia woodland on the southern and eastern edge of the Kalahari, South Africa. Trees in which there were tree rat nests were compared with trees of similar size and vigour to identify the characteristics of nest sites. Spatial analysis of tree rat distribution was conducted using Ripley's-L function. We found that T. nigricauda was able to utilize all available tree species, as long as trees were large and old enough so that cavities were existing inside the stem. The spatial distribution of nest trees did not show clumping at the investigated scale, and we therefore reject the notion of the rats forming colonies when inhabiting continuous woodlands. The selection of a particular tree as a nest site was furthermore depending on the close proximity of the major food plant, Acacia mellifera. This may limit the choice of suitable nest sites, since A. mellifera was less likely to grow within a vegetation patch containing a large trees than in patches without large trees. 相似文献
12.
在福建洋口林场4年生的杉木人工林建立固定试验标准地．选择修枝木,每年对其进行1次修枝,修枝强度为修去4种规定树干直径（6cm、8cm、10cm和12cm）以下的所有枝条．修枝试验后2年,随着修枝强度的增加,杉木的生长量明显降低．修枝强度为6cm（密度1200株·hm^-2）的修枝木的平均树高、平均胸径和平均单株材积增长量均显著低于不修枝木．修枝后2年,各修枝处理杉木林林下植物的覆盖度、生物量、总的物种数,灌木层、草本层和总体Shannon-Wiener指数均高于未修枝的对照,但藤本层植物在修枝时被大量劈除,其种类数量、多样性指数却低于对照．闽北生产力较高的4年生、密度1200株·hm^-2的杉木幼林进行修枝,推荐的修枝强度为10cm或12cm． 相似文献
13.
黄土高原丘陵沟壑区植被恢复重建后的物种多样性研究 总被引：39，自引：0，他引：39
黄土高原丘陵沟壑区是我国物种多样性研究相对较薄弱的地区。目前关于该区植被恢复重建后的物种多样性研究尚未见报道。研究该区植被恢复重建后的物种多样性对退化生态系统的植被恢复重建具有重要的指导意义。本文选取6个物种多样性指数对纸坊沟流域主要的天然及人工群落物种多样性进行了研究，研究发现：天然灌木林物种多样性最高，均匀度最大，人工乔木林和天然草本的物种多样性及均匀度接近，人工灌木林的多样性和均匀度最小。人工林纯林（包括纯乔木林、纯灌木林及单一乔灌混交林）具有很强的抵抗其它乔灌物种入侵和定居的能力，对林下草本也有很强的控制能力。因此，要建造一个具有较高物种多样性的群落，在建造初期就要选择多物种混交，并注意初值密度。 相似文献
14.
Assessing Natural and Cultural Determinants of Urban Forest Quality in Nanjing (China) 总被引：1，自引：0，他引：1
《自然地理学》2013,34(5):455-473
This study assessed underlying natural and cultural determinants of tree health and ways to improve urban forest performance in compact Nanjing city. Two groups of factors were investigated: (1) habitat conditions, including planting site, ground-cover, land cover, and district; and (2) tree traits, including species provenance and seasonality, and tree dimensions. A stratified sampling strategy selected 6351 trees for detailed assessment. The data were analyzed by multivariate logistic regressions. Institutional, park-garden and industrial trees with more open-space sites with vegetated ground-cover performed better than roadside and residential ones. Poor trees in confined residential sites deviated from those in other cities. Park-garden sites did not always nurture meritorious, large and diversified trees. District differentiation in tree performance was related to land cover. Exotic and evergreen species grew better than indigenous and deciduous, offering hints on species-habitat matching. Detailed field and statistical analyses could yield tree-environment information to enhance urban forestry research and management. 相似文献
15.
Gufu Oba Inger Nordal Nils C. Stenseth Jrn Stave Charlotte S. Bjor Josphat K. Muthondeki William K. A. Bii 《Journal of Arid Environments》2001,47(4):499
In the arid zone of central Turkana, north-western Kenya, where soil salinity affects 15–20% of the rangelands, growth performances of trees planted in saline soil rehabilitation trials have not been evaluated. Tree-planting trials have emphasised exotic species over indigenous ones. However, advantages and disadvantages of promoting exotic tree species have not been examined. The current study was aimed at evaluating growth performance of seven exotic and nine indigenous tree species used in saline soil rehabilitation trials. The tree species were established from 6-month-old saplings using microcatchments (FT1) from 1988 through 1990 and pitting treatment (FT2) from 1989 through 1992. The soils in FT1 and FT2 treatments were moderately to highly saline. The exotic tree species produced greater cover and volume during the first year (FT1) but by the second year, production was not sustained due to greater mortality (FT1 & FT2). The indigenous species in general had higher survival rates. Relative growth rates (RGR) of exotic and indigenous species did not differ (FT1 & FT2). Tree mortality was negatively correlated with RGR for exotic species in FT1 but not for indigenous ones. However, changes in plant performance were not in response to salinity alone. Rather, water scarcity superimposed on soil salinity might have influenced plant growth performance. Greater water and salinity stress and subsequently greater mortality in exotic species provided a more convincing reason for promotion of indigenous tree species. In the future, knowledge of salinity distribution and selection of indigenous species to match this will be a better way of rehabilitating sites affected by soil salinity in the arid zone of central Turkana, north-western Kenya. 相似文献
16.
黄土丘陵区坡面尺度上不同植被格局下植物群落和土壤性质研究 总被引：1，自引：0，他引：1
通过对黄土丘陵沟壑区陕西延安羊圈沟小流域坡面上退耕还林还草后形成的林地(单一种植刺槐人工林)、草地(单一的撂荒草地)、草地-林地-草地(上坡位和下坡位撂荒草地,中坡位种植刺槐人工林)及林地-草地-林地(上坡位和下坡位种植刺槐人工林,中坡位为撂荒草地)四种不同的植被格局下植物物种多样性及土壤理化性质变化的研究,旨在揭示植被恢复过程中,坡面上植被不同的空间配置模式对植物物种的组成及土壤环境变化的影响.研究发现,4种植被格局下植物物种的多样性以单一的撂荒草地坡面最高,人工林的种植一定程度上影响了林下植物物种多样性的恢复,但整个灌木和草本的群落结构4种植被格局之间均未达到极不相似水平.土壤有机碳及总氮含量均以坡面上草地-林地-草地的空间配置格局最高且有机碳存在显著差异,而撂荒草地则在土壤水分的保持及改善土壤pH值上优于其他3种植被格局. 相似文献
17.
Changes in soil nutrients, vegetation structure and herbaceous biomass in response to grazing in a semi-arid savanna of Ethiopia 总被引：1，自引：0，他引：1
The effect of grazing was studied on vegetation structure, herbaceous biomass, basal and bare ground covers, together with soil nutrient concentrations in two locations in an Ethiopian semi-arid savanna. The lightly grazed sites had significantly higher herbaceous diversity, total abundance, basal cover and aboveground biomass, and a lower percentage of bare ground compared with the heavy grazed sites. Grazing pressure had no effect on the density and number of woody species as well as on the proportion of encroaching woody species. The light grazing sites had higher organic carbon, phosphorus and exchangeable bases, and therefore a higher pH and higher electrical conductance, indicating an improved soil nutrient status compared with heavy grazing sites, mainly attributed to the higher basal cover and standing biomass at light grazed sites, and the export of nutrients through grazing and dung collection from the heavily grazed sites. There were significantly higher soil nutrients, species diversity, aboveground biomass and basal cover in the light grazing sites compared with heavy grazing sites. We concluded that changes in herbaceous vegetation, standing biomass and soil compositions are caused by interactions between grazing, soil and vegetation, and these interactions determine the transitions of semi-arid savannas. 相似文献
18.
Oligotrophic bacteria have been isolated from many habitats, yet environmental regulation of their distributions in soil has not been elucidated. To address the issue of environmental influence upon oligotrophic distributions, Chihuahuan Desert soils were sampled from five sites along an elevational and vegetational gradient within Big Bend National Park during January and August of 2002 and 2003. Soils were diluted and plated on oligotrophic media, and plates were incubated at 15, 25, 35, 45 and 60 °C. Additionally, measurements of soil organic matter, pH, moisture, extractable nitrate, extractable ammonium and microbial biomass carbon were collected for each sample to relate oligotrophic bacterial distributions to soil nutrient and edaphic characteristics. Analysis of variance indicated significant site, season, incubation-temperature and interaction effects on total oligotroph numbers. Canonical correspondence analysis and multiple regressions indicated that all soil-chemistry variables significantly influenced discrete morphologies of oligotrophs. Oligotroph distributions were most congruent with soil-chemistry variation in three sites, whereas oligotrophic diversity in two sites did not adhere closely to measured environmental variables. While vegetation type may structure oligotroph communities at the two mid-elevational sites, abiotic constraints are drivers in low-desert sites. 相似文献
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20.
以黑河中游人工绿洲边缘天然草地及其转变的人工梭梭灌木林（21 a）、人工杨树林（28 a）、人工樟子松林（33 a）和农田（开垦27 a和100 a）为研究对象,基于6种研究样地中小型土壤动物群落的调查数据,采用多变量排序和通径分析等方法,研究了土地利用/覆被变化与管理措施对中小型土壤动物群落及其主要类群演变的耦合效应。主要结果是:①将天然草地转变为未实施管理措施的人工梭梭灌木林后并未引起土壤动物群落组成、数量和物种多样性的显著变化,而转变为实施管理措施的杨树和樟子松人工林及农田后,导致了土壤动物群落组成、数量和物种多样性的变异,证实了土地覆被变化对中小型土壤动物群落的作用及其效应受管理措施的强烈调控。②土壤动物群落的演变过程受土地覆被变化与灌溉和施肥管理的共同影响,其中灌溉的贡献率最大,是关键驱动因子。③不同土壤动物类群对土地覆被变化和管理耦合作用的响应不同。灌溉对跳虫、甲螨和革螨的个体数量和物种丰富度的直接影响和总效应最大;施肥对辐螨的个体数量和物种丰富度的直接影响和总效应最大;灌溉和施肥对稀有类群的个体数量和物种丰富度的直接影响和总效应均较大,具同等重要的作用。结论是,土地覆被变化与管理耦合作用通过改变土壤水文和生态环境条件驱动了中小型土壤动物群落的演变过程。 相似文献