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1.
Protected areas have had significant impacts on local communities primarily through the physical removal of people. In some instances, people continue to live within protected areas due to the inability of the state to evict them. The restrictions on livelihoods placed on people living inside protected areas lead to in situ displacement. We show how conservation enclosures in the Biligiri Rangaswamy Temple Tiger Reserve have produced a class of people that the state ‘lets die’ by banning customary practices such as fire use, hunting and harvesting of forest produce. Using longitudinal ethnographic, socio‐economic and ecological data, we demonstrate that conservation policy has alienated indigenous forest dwellers from their agricultural and forest‐land. The outcomes of conservation policy include dispossession through increased crop losses, reduced income from agriculture and forest produce, as well as a forest that is dominated by weeds due to fire suppression. The ban on hunting in particular has increased wildlife densities, which has enabled the state to accumulate revenues through the establishment of wildlife tourism facilities. All in all, centralized protected area governance has changed the relationships among people, forest and the state in a way that has produced adverse effects for both livelihoods and the ecosystem.  相似文献   

2.
The most pervasive threats to biological diversity are directly or indirectly linked to the road networks. For this reason, over the last few decades, interest in the study of the ecological characteristics of the edges associated with roads has increased. This work aims to investigate the effect of roads as a human-induced disturbance on the plant diversity in two managed Mediterranean forest sites, focusing on the responses of plants species richness, evenness, composition and taxonomic diversity.A stratified random sampling was performed in two protected areas located in Tuscany, Central Italy. The species richness, composition and abundance were measured in 53·20 × 20 m plots. Ordinary Least Square and quantile regressions were used to study the effect of the roads on species richness, evenness and taxonomic distinctness, and redundancy analysis was used to examine the species composition. Generalized linear models in conjunction with an Information Criterion-based approach to model selection were used to test the role of road distance in the structure of forest plant biodiversity.Our findings indicated a clear relationship between road distance and different plant biodiversity facets, which showed its maximum effect in the first 0–20 m forest-to-road segment and a mitigation after the 200 m threshold. Furthermore, the presence and abundance of many key forest species, such as Fagus sylvatica and Abies alba, were influenced more by the road distance than by other environmental gradients. The few remnants of core forest habitats in the Mediterranean basin highlight the need to recognize that road construction and maintenance have several ecological implications and accordingly require long-term monitoring programs.  相似文献   

3.
The purpose of this study was to elucidate the floristic and structural characteristics of simple alluvial fan vegetation of southern Sinai and to relate them to environmental variation. The main question addressed was: how does the floristic composition of fan habitats, species richness and life-form vary in relation to environmental change? Thirty-seven alluvial fans, randomly selected in two mainwadis(WadiFeiran andWadiDahab) were analysed quantitively. Two-way Indicator Species Analysis (TWINSPAN) classification and Canonical Correspondence Analysis (CCA) were applied in successive stages of the data analysis to describe vegetational variation in relation to physical gradients. Seven main clusters of fans were defined on the basis of environmental variation. These clusters are divided into three main groups of species richness. Species richness varied along a moisture gradient. The richest fans were the driest habitats, indicating that maximum species richness did not occur at high moisture availability. The moisture gradient is a complex gradient correlated with elevation, slope, climatic aridity, soil texture and the nature of the soil surface. Fine sand, silt plus clay and calcium carbonate showed significant differences between the internal groups and subgroups of the first and second level of the TWINSPAN classification.  相似文献   

4.
The Royal Belum forest reserve is one of the oldest tropical rainforests in the world and it is one of the largest virgin forest reserves in Malaysia. However, not many studies have been conducted to understand the ecology of this forest. In this study we estimated the aboveground biomass (AGB) of the forest using diameter at breast height (DBH) and height of trees (h ), tree species and hemispherical photographs of tree canopy. We estimated AGB using five allometric equations. Our results demonstrated that the AGB given by the one tree species specific allometric equation does not show any significant differences from the values given by the non‐tree species specific allometric equations at tree and plot levels. The AGB of Intsia bijuga species, Koompassia malaccensis species and Shorea genera were comparatively higher, owing to their greater wood density, DBH and h. This has added importance because some of these species are categorized as threatened species. Our results demonstrated that mean AGB values in this forest (293.16 t ha‐1) are the highest compared to some studies of other areas in Malaysia, tropical Africa and tropical Bazilian Amazonia, implying that the Royal Belum forest reserve, is an important carbon reservoir.  相似文献   

5.
《自然地理学》2013,34(6):481-498
A number of studies have elucidated the distributional patterns of various components of Southern Appalachian forests. The evergreen understory here is composed largely of a dominant ericaceous shrub, Rhododendron maximum L., which is believed to be expanding and inhibiting the development of other species with consequent impacts on overall forest structure and composition. We use a GIS and logistic regression to examine this less-studied forest element in the Coweeta Hydrological Laboratory, North Carolina, over a 17-year period to determine whether expansion is occurring and, if so, whether it can be predicted based on terrain characteristics. We examine two adjacent, physically similar basins with differing degrees of experimental manipulation in the 20th century in an attempt to examine the role of environmental and historical factors in determining spatial patterns of persistence, expansion, and decline of the evergreen understory. Results indicate that significant expansion of the evergreen understory occurred in both basins during the period 1976-1993, and that stream proximity, topographic setting, and elevation are related to patterns of evergreen-understory dynamics. Patterns differ between the two basins, suggesting that disturbance and differing land-use histories are also influential. Predictive power of models based on terrain factors alone ranges from <10% to >50%.  相似文献   

6.
The transformation of tropical ecosystems by humans have resulted in forest loss, which, in turn, have caused negative impacts on biodiversity and the provisioning of ecosystem services. There is an urgent need to plan the restoration of these human-modified landscapes, using methodological approaches that consider key processes occurring at different spatial scales while engage local community participation, offering them the best possibilities of tangible benefits. In this study, was evaluated the landscape spatial pattern and local conservation status of existing forest remnants, showing an analysis of possible restoration scenarios for a human-modified landscape in La Montaña, an indigenous region in southwestern Mexico. Therefore, landscape and local scale approaches were linked to identify specific landscape elements where efforts to improve connectivity must be concentrated. Also, this approach allowed finding a set of species from reference sites that showed the best socioecological characteristics to be used in different restoration strategies. As expected, La Montaña region showed a spatial pattern typical of highly human-modified landscapes, i.e., several small (<21 ha) and irregular forest remnants with strong forest edge effects. Furthermore, these small and irregular forest fragments displayed forest structure, diversity and composition characteristics similar to those communities disturbed by selective harvesting or in an early successional phase. However, about 100 of woody species were found inside the fragments, some with important potential to provide ecosystem services. The landscape connectivity was very low, and an analysis of possible restoration scenarios showed that is equally important to restore the productive areas as well as open forest, to recover up to 47% of landscape connectivity. In this sense, it was proposed a productive restoration strategy to enrich open forests and create biodiversity-friendly habitat in agricultural areas, using species with high socioecological potential. We believe that the same approach could be applied to other highly human-modified tropical landscapes with similar socioecological problems.  相似文献   

7.
Species composition and factors that control the distribution of freshwater swamp forests in West Africa are largely unknown. To achieve this, 24, one‐hectare forest plots were established to assess the tree species (DBH ≥ 10 cm) distribution across the ecosystem. A total of 138 species within 100 genera and 41 families were distributed across the forest plots and 47 species were identified as indicator species. These indicator species were used to constrain the species‐environmental categories across three broad habitat types: the disturbed freshwater zone, the mangrove‐freshwater transition zone and the intact freshwater zone. While 40 species are associated with one of the three forest categories, seven of them coexisted in disturbed and mangrove‐freshwater zones. Disturbance (local factors) was identified as the most important determinant of the species distribution followed by the climatic factors. Future climate predictions for the locations are quite variable and suggest that some species may be non‐viable as the ecosystem's composition may alter. While the indicator species provides insights on the species‐environment relationships, and is useful for informing forest conservation and planning, their tendency to continually co‐exist with others and provide vital functions is dependent on how sustainably the people use them.  相似文献   

8.
Natural regeneration of abandoned farmland in several areas within the catchments of the Sydney Water Board has been very slow. Several hypotheses have been put forward to explain the fact that natural reforestation has not occurred, even after up to 50 years of abandonment. This study examines regeneration in relation to substrate, soil types and soil chemistry. The abandoned farmlands occur on four main soil types: (i) eutrophic krasnozem, now occupied mainly by bracken fern (Pteridium esculentum) associated with young seedlings of Eucalyptus and Acacia; (ii) mesotro‐phic yellow earth, now occupied by blady grass (Imperata cylindrica), with few tree seedlings and scattered, dead Acacia trees; and (iii) mesotrophic alluvial soil, and (iv) oligotrophic lithosol, which both support stands of Acacia. The soil properties of the krasnozem and the yellow earth appear to be suitable for tree establishment and growth, and do not differ from similar soils in nearby areas currently under cultivation or supporting undisturbed forest. Poor forest establishment in these soils might be the result of frequent fires and biotic factors such as competition from the bracken and blady grass sward. The lack of eucalypt reforestation of the poorer soils might be explained by their poorer fertility, perhaps tolerated better by the Acacia species.  相似文献   

9.

The goal of this research was to implement an optimization model that allows definition of best management strategies in the forest sector. The case study is depicted in a coniferous stand (silver fir—Abies alba Mill.) of Tuscany (central Italy). Four ecosystem services were quantified from biophysical (timber produced, carbon stored, ecosystem diversity, recreational function) and economic (total economic value of the above parameters) perspective. The indicators are aggregated through a multi-objective approach (compromise programming). In the framework of forest seen as complex adaptive systems, different management strategies can lead to emergent reaction of forest functions. Due to nonlinear and non-continuous interactions as well as to the presence of feedbacks and loops among environmental and socioeconomic forest components, results are optimized by means of differential evolution and particle swarm algorithm. The genetic algorithm was applied to minimize the distance from ideal point. The best value of the decision variable (rotation period) was defined for different scenarios based on compensatory level of criteria, constraints and presence/absence of forest thinning. Conflicting trends and trade-offs are highlighted when different criteria were optimized. Among outputs, thinning intervention seems to reduce the performance of several criteria in the study area. Strengths and weaknesses of the model as well as potential future improvements are finally discussed.

  相似文献   

10.
Invasive plant species are a growing concern in many regions of the world, yet little information is available on the effects of habitat type and distance to urban settlements on the ability of alien plants to become established. We studied plant communities from the arid steppes to the Andean forest within two national parks and surroundings, in northwestern Patagonia, Argentina. Alien and native vascular plant species were sampled using 90 × 100 m2 plots and analyzed in relation to both climatic and environmental variables and distance to urban centres. We also compared life-forms of alien and native species. Precipitation and distance to an urban centre were important determinants of alien species community richness and composition, and shrubland sites had significantly more alien species than forest or steppe sites. Alien flora (15% of the species) was composed of a higher proportion of annuals and biennials than native flora. Our results suggest that precipitation, distance to source population, and anthropogenic disturbance influence the invasion process in this region, together with the availability of open niches. This work stresses the importance of monitoring invasive species in natural reserves, and of considering habitat types as well as idiosyncratic characteristics of the non-natives for developing management strategies.  相似文献   

11.
辽东山地老秃顶子古冰缘地貌植物种群生态位特征   总被引：1，自引：0，他引：1  
伏捷  孙才志  张华  何红  祝业平  王颖 《地理研究》2018,37(4):731-741
基于48块样地的群落调查数据,以样地代表多种资源的综合状态,以物种重要值作为生态位计测的状态指标,采用Levins指数与Schoener指数,对辽东山地老秃顶子古冰缘地貌植物群落乔木层、灌木层及草本层植物的生态位特征进行了系统研究。结果表明：① 乔木层内臭冷杉（Abies nephrolepis）生态位宽度最大,为泛化乔木种;臭冷杉与长白鱼鳞云杉（Picea jezoensis var. komarovii）的生态位重叠值高达0.616,共优生存于暗针叶林中。② 灌木层内生态位宽度较大的狗枣猕猴桃（Actinidia kolomikta）、单花忍冬（Lonicera subhispida）、大翅卫矛（Euonymus macropterus）和关东丁香（Syringa velutina）为落叶阔叶林和针阔混交林下的泛化种;狗枣猕猴桃与单花忍冬的生态位重叠值高达0.610。③ 草本层内生态位宽度较大的东北羊角芹（Aegopodium alpestre）、荨麻叶龙头草（Meehania urticifolia）、酢浆草（Oxalis corniculata）为研究区泛化草本植物;东北羊角芹与荨麻叶龙头草的生态位重叠值高达0.702。  相似文献   

12.
A floristic quadrat study of sparsely wooded plains on western Melville Island was conducted and used to define and describe floristic and structural vegetation types and identify their associated environmental correlates. The results were compared with an existing land‐unit survey of the area in order to identify the relative merits of these schemes for conservation planning. All schemes identify a range of broad structural types including Acacia shrubland, Grevillea pteridifolia low woodland, Lophostemon lactifluus low woodland, and Banksia dentata low woodland. However, some of the structural and land‐unit types are composed of two plant communities with distinctive environmental relations. Despite being structurally distinctive, some community types are floristically indistinguishable from surrounding forest dominated by Eucalyptus miniata and E. tetrodonta. The number of species captured by randomly selecting sites from each classificatory type revealed little difference between schemes. All the classificatory approaches were less effective at species capture than a simple iterative procedure. Some of the plant communities seem to be unique and require preservation initiatives in the face of current forestry operations and planned horticultural development.  相似文献   

13.
Forest‐transition theory suggests that economic development eventually leads to forest recovery, but there is great uncertainty about the existence, the characteristics, and the mechanisms of forest transitions that might be occurring under current socioeconomic conditions. A case study in a small region of highland Mexico finds agricultural abandonment and forest regeneration, but also forest degradation due to woodcutting. A discussion locates those findings in the international political economy of agriculture and emigration in Mexico, which are substantially different from the conditions associated with forest recovery in developed countries. Although regional forest transitions are possible in marginal agricultural areas such as that studied here, their environmental implications depend on the evolution of social institutions coordinating rural people's environmental actions.  相似文献   

14.
片断化热带雨林土壤种子库初步研究   总被引：4，自引：1，他引：3  
唐勇  曹敏  白昆甲 《山地学报》2000,18(6):568-571
通过萌发实验研究片断化热带雨林的森林土壤种子库的储量、种类组成以及种子的分布。结果表明,在厚度为10cm的土壤中,受次生植被隔离的城子龙山雨林片段土壤种子库储量达到6494±155粒/m2,高于连续森林的4585±235粒/m2。而受人工植被隔离的曼仰广龙山雨林片段由于缺乏种源,土壤种子库储量较低,仅达到3505±43粒/m2。土壤种子库中的种子种类也以城子龙山为最多,达到69种。从土壤种子库的水平分布看,受次生植被影响的城子龙山和迁地保护区从林缘至林内种子储量呈下降的趋势,而需子龙山隔离程度较高、受人畜干扰严重,森林内外土壤种子库储量显差异不显著。  相似文献   

15.
树轮稳定同位素比率是研究气候变化与环境演变的有效代用资料,耦合分析树轮稳定同位素记录的信息可揭示森林生态系统碳—水—氮时空变化特征及相互作用,反映环境变化对植物特定化合物的生理影响。树轮稳定氮同位素比率（δ15N）与树木生长的环境条件密切相关,其变化可以反映长时间尺度森林生态系统氮循环的动态特征,弥补监测资料的不足。本文综述了树轮稳定氮同位素的分馏机理与测定方法,解析了树轮δ15N在样品预处理和测试中需要关注的问题,系统梳理与归纳了基于树轮δ15N进行气候变化、环境演变和人类活动氮排放研究的进展。指明中国树轮稳定氮同位素研究潜力及其在未来亟需着重发展的方向,旨在推动森林生态系统氮循环时空特征深入研究。  相似文献   

16.
A treeline can respond to climate change by shifting position, infilling, increasing recruitment, and increasing radial growth. More studies from understudied areas and their associated species are needed to understand treeline structure and dynamics. We established two transects of 20 m width and 120 m length (100 m above and 20 m below the forestline) in the Betula utilis subalpine forest of the Dhorpatan Hunting Reserve in Western Nepal. All individuals of B. utilis within the transects were classified into three height classes – trees (>2 m), saplings (0.5–2 m), and seedlings (<0.5 m) – and measured for morphometric features. Tree-ring cores were collected for age structure analysis. B. utilis forms an abrupt treeline in the region, and the mean forestline and treeline elevations were 3893 and 3898 m, respectively. The average age (57 yr) of trees at the treeline ecotone suggests a young stand. Poor regeneration was observed above the forestline in both transects when compared to below the forestline. Low regeneration at the treeline ecotone suggests site-specific biotic and abiotic controlling factors. Seedling and sapling establishment above the forestline is limited by a lack of moisture, absence of suitable microsites, and presence of herbivores.  相似文献   

17.
Patterns of association of three columnar cactus species with potential nurse plants and rocks were examined in Organ Pipe Cactus National Monument, Arizona. Close spatial associates of cacti are often called “nurses” because they provide a less extreme microclimate for cactus seedlings, which improves survival rates. Of the three cacti, Carnegiea gigantea had the greatest frequency of association with nurse plants. Stenocereus thurberi, which is common on steep hillslopes where rocks and crevices offer numerous protected microsites for seedling establishment, was associated with nurse rocks more frequently than were the other two species. Lophocereus schottii showed the lowest frequency of association with nurses. In the Monument, L. schottii reproduces primarily through vegetative propagation, which reduces the need of small cacti for protection from nurses. Species most frequently associated with the three cacti were among the dominant species where each cactus occurred except that sparsely foliated species were associated with cacti less frequently than expected. This pattern supports previous claims that structural characteristics are more important than species identification in providing cacti with enhanced chances for survival. It also suggests that at a landscape scale, population dynamics of columnar cacti are more closely linked to patterns of overall vegetation change than to population fluctuations of a particular species that acts as a nurse. [Key words: northern Sonoran Desert, cactus establishment, nurse plants.]  相似文献   

18.
From July 2008 to August 2008, 72 leaf samples from 22 species and 81 soil samples in the nine natural forest ecosystems were collected, from north to south along the North-South Transect of Eastern China (NSTEC). Based on these samples, we studied the geographical distribution patterns of vegetable water use efficiency (WUE) and nitrogen use efficiency (NUE), and analyzed their relationship with environmental factors. The vegetable WUE and NUE were calculated through the measurement of foliar δ 13C and C/N of predominant species, respectively. The results showed: (1) vegetable WUE, ranging from 2.13 to 28.67 mg C g-1 H2O, increased linearly from south to north in the representative forest ecosystems along the NSTEC, while vegetable NUE showed an opposite trend, increasing from north to south, ranging from 12.92 to 29.60 g C g-1 N. (2) Vegetable WUE and NUE were dominantly driven by climate and significantly affected by soil nutrient factors. Based on multiple stepwise regression analysis, mean annual temperature, soil phosphorus concentration, and soil nitrogen concentration were responding for 75.5% of the variations of WUE (p<0.001). While, mean annual precipitation and soil phosphorus concentration could explain 65.7% of the change in vegetable NUE (p<0.001). Moreover, vegetable WUE and NUE would also be seriously influenced by atmospheric nitrogen deposition in nitrogen saturated ecosystems. (3) There was a significant trade-off relationship between vegetable WUE and NUE in the typical forest ecosystems along the NSTEC (p<0.001), indicating a balanced strategy for vegetation in resource utilization in natural forest ecosystems along the NSTEC. This study suggests that global change would impact the resource use efficiency of forest ecosystems. However, vegetation could adapt to those changes by increasing the use efficiency of shortage resource while decreasing the relatively ample one. But extreme impacts, such as heavy nitrogen deposition, would break this trade-off mechanism and give a dramatic disturbance to the ecosystem biogeochemical cycle.  相似文献   

19.
贵州中部地区有大型菌物168种,隶属31科,64属．分属于阔叶林型、针叶林型、针阔混交林型．其中担子菌154种,57属,28科;子囊菌14种,7属,5科．  相似文献   

20.
Species ranges are often represented using polygons, with the attendant issues that they show uniform ranges with abrupt boundaries and can overestimate species ranges. We demonstrate that such uniform species ranges can be supplemented by mapping the gradational variation in species turnover across a landscape. Directional variation in species turnover for 15 skink species (Reptilia: Scincidae) and topographic and climatic turnover in south-eastern Australia were measured using directional moving window analyses, rotated through 360°. The resultant species turnover maps were compared with published polygon range maps for two species within the group (Liopholis whitii and L. inornata). We also assessed how the relationships between species and environmental turnover varied in areas of low or high species turnover. Continuous transitions between distinct areas of low and high species turnover were mapped. Low turnover comprised only 19% of the L. whitii polygon species range within the study area extent. These low turnover areas were more densely populated by L. whitii (67% of observations), whereas areas of medium to high turnover contained substantially fewer observations (25%). Regions with the highest species turnover contained only 6% of observations. L. inornata observations were also clustered in low species turnover areas. Averaged climatic and elevation values were higher in low-turnover areas despite their close adjacency to high-turnover zones. The environmental turnover in low species turnover regions was also lower than in high-turnover areas. Correlations between environmental turnover and low species turnover areas were positive, whereas the opposite relationship applied in high species turnover areas. We identified both abrupt and gradual distributional breaks between separate reptile assemblages; an example of the latter is located in the Hunter Valley in the south-eastern coastal region. This break has been mapped using solid, uniform lines in species ranges and thus implicitly as an abrupt break. Environmental conditions may be more favourable to skinks in low-turnover areas. Since L. whitii and other skink species have very large populations in low-turnover areas, other squamate species may also be more likely to occur in these areas. This has potential implications for conservation prioritisation. The turnover maps used here can supplement the information provided about reptile distributions by the equivalent polygon ranges. This approach can be applied to point occurrence data for any taxonomic group or any similar georeferenced diversity data set.  相似文献   

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