首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 203 毫秒
1.
The limited spatial scales of many bird–habitat studies restrict inference regarding large scale bird–habitat relationships. A potential solution to this challenge is integrating the USFS Forest Inventory and Analysis (FIA) and USGS Breeding Bird Survey (BBS) databases. We describe a methodology for integrating these databases into a uniform dataset for modeling bird–habitat relationships at multiple spatial scales. We accumulated route-level BBS data for four species guilds (canopy nesting, ground-shrub nesting, cavity nesting, early successional), each containing a minimum of five bird species. We developed 43 forest variables at the county level using FIA data from the 2000 inventory cycle within 5 physiographic regions in 14 states. We examined spatial relationships between the BBS and FIA data at three hierarchical scales: (1) individual BBS routes, (2) FIA units, and (3) physiographic sections. At the BBS route scale, we buffered routes at 100 m, 1 km, and 10 km radii, intersected these buffers with county boundaries, and developed weighted averages for each forest variable within each buffer width. Weights were a function of the percent of area each county had within a buffer. We calculated 29 landscape structure variables from 1992 National Land Cover Data (NLCD) imagery using Fragstats within each buffer width. At the BBS route scale, we developed models relating variations in bird occupancy and abundance to forest and landscape structure within each buffer width using classification and regression trees (CART). We aggregated the FIA variables to the FIA unit and physiographic section scales and recalculated the landscape variables within each unit and section using NCLD imagery resampled to a 400 m pixel size. We used regression trees (FIA unit scale) and general linear models (GLM, physiographic section scale) to relate variations in bird abundance to the forest and landscape variables. At the BBS route scale, 80% of the best CART models accounted for >50% of the variation in bird occupancy and abundance. Among FIA units and physiographic sections, the regression trees accounted for an average of 54.1% and the GLMs accounted for an average of 66.3% of the variability in bird abundance, respectively. This methodology shows promise for integrating independent databases for evaluating bird–habitat relationships across broad spatial extents, and the hierarchical nature of these models provides a potentially consistent means of evaluating management options at varying spatial scales.  相似文献   

2.
森林风景资源是森林旅游开发的物质基础,其空间分布的离散度调查是森林旅游开发建设的前提条件。通过对福建省森林风景资源调查,把福建省的森林风景类型划分为10大类43亚类,并进一步分析全省的主要森林景观类型的时空分布、景观多样化变化,为福建省森林旅游发展规划以及森林旅游景区开发建设提供参考依据。  相似文献   

3.
森林景观计量评价与福建森林景观的开发应用研究综述   总被引:9,自引:0,他引:9  
兰思仁 《华东森林经理》2001,15(4):53-57,42
归纳总结出对现实森林景观进行计量化评价的实用方法,该方法由森林景观的三个评价内容加权求和而成,即森林景观美景度(SB)、视觉吸收力(VAC)和风景敏感水平(SL)三部分。以福州国家森林公园为研究实例,运用该方法对公园的各种森林景观类型(专类园)进行计量评价,评价结果与实际情况相一致。在此方法基础上,探讨了森林景观资产评估方法,阐述了福建省森林景观的地理概述和不同森林景观类型的分布格局,进行福建省森林旅游区划和游览路线的组织和开发,为福建省森林生态旅游的深化发展提供理论和科学依据。  相似文献   

4.
Large areas assessments of forest biomass distribution are a challenge in heterogeneous landscapes, where variations in tree growth and species composition occur over short distances. In this study, we use statistical and geospatial modeling on densely sampled forest biomass data to analyze the relative importance of ecological and physiographic variables as determinants of spatial variation of forest biomass in the environmentally heterogeneous region of the Big Sur, California. We estimated biomass in 280 forest plots (one plot per 2.85 km2) and measured an array of ecological (vegetation community type, distance to edge, amount of surrounding non-forest vegetation, soil properties, fire history) and physiographic drivers (elevation, potential soil moisture and solar radiation, proximity to the coast) of tree growth at each plot location. Our geostatistical analyses revealed that biomass distribution is spatially structured and autocorrelated up to 3.1 km. Regression tree (RT) models showed that both physiographic and ecological factors influenced biomass distribution. Across randomly selected sample densities (sample size 112 to 280), ecological effects of vegetation community type and distance to forest edge, and physiographic effects of elevation, potential soil moisture and solar radiation were the most consistent predictors of biomass. Topographic moisture index and potential solar radiation had a positive effect on biomass, indicating the importance of topographically-mediated energy and moisture on plant growth and biomass accumulation. RT model explained 35% of the variation in biomass and spatially autocorrelated variation were retained in regession residuals. Regression kriging model, developed from RT combined with kriging of regression residuals, was used to map biomass across the Big Sur. This study demonstrates how statistical and geospatial modeling can be used to discriminate the relative importance of physiographic and ecologic effects on forest biomass and develop spatial models to predict and map biomass distribution across a heterogeneous landscape.  相似文献   

5.
The sustained increase in the global food demand has favoured the recent expansion of industrial agriculture into neotropical dry forest ecosystems, with resulting changes in their extent and spatial configuration. Based on Landsat satellite images, we analyzed changes in forest cover and landscape configuration over an area of 600 by 100 km located in NW Argentina (Tucumán and Salta provinces) in four periods between 1972 and 2007. The study area, one of the most active deforestation frontiers of South American dry forest, was divided into six relatively homogeneous sectors in terms of land property structure and biophysical characteristics. During the study period 1.4 millions hectares of dry forest were cleared. Deforestation started in the 1970s as a result of technological changes and increasing rainfall; continued (with spatial and temporal fluctuations) during the 1980s and 1990s in association to the sustained global demand of soybean, and was accelerated (to ca. 100,000 ha year−1) between 2001 and 2007 following the global increase in commodity prices, and the national peso devaluation. We described the landscape structure using eight landscape indices, summarized as one synthesis value: the Euclidian distance across the seven dimensions from a theoretical non-fragmented situation. In areas with soil limitations deforestation resulted in relatively stable, highly fragmented landscapes. In contrast, the sites with regional coarser-scale limitations (rainfall), deforestation produced a less fragmented landscape where agriculture concentrates in sites with high rainfall. Sites with no limitations for agriculture tend to a largely deforested landscape with few small and poorly connected forest patches. The land properties size seems to influence some indices of fragmentation, but the synthetic index of fragmentation suggests an overall convergence of fragmentation patterns towards a similar configuration across different biophysical and land tenure conditions.  相似文献   

6.
Fuel treatments for reducing fire risk are necessarily tied to the landscape structure including forest composition and configuration. Thus understanding the relationships between landscape structure and burn severity is important for developing guidelines and management strategies for fire-resilient forests. The goal of this study was to investigate the relationship between landscape structure as described by spatial pattern metrics and burn severity at the landscape and class levels. In 2000, a mostly severe fire burned 16,210 ha of dense forest located in Samchuck on the east coast of the Korean peninsula. Spatial pattern metrics including patch density, largest patch index, mean shape index, area-weighted mean shape index, Euclidean nearest neighborhood distance, and Shannon's diversity index, as well as topographic characteristics of slope and elevation, were correlated with burn severity based on delta Normalized Burn Ratio (dNBR) assessments. Regression tree analysis was also carried out with the same variables to avoid spatial autocorrelation and to reveal the relative importance of variables to burn severity. The results of this study strongly suggest that both composition and configuration of the forest cover patches are closely tied to burn severity. In particular, both the correlation analysis and regression tree analysis indicated that the area of red pine tree forest cover was the most significant factor in explaining the variance of burn severity. Topography and spatial configuration of forest cover patches were also significantly related to burn severity. The heterogeneity of forests also had a significant influence on burn severity. To reduce fire risk and increase the fire resilience of forests, forest managers and agencies need to consider enhancing the heterogeneity of forests when implementing fuel treatment schemes. However, such fuel treatments for landscape structure may only be effective under moderate weather conditions.  相似文献   

7.
In this study, we identified the distribution characteristics of a mixed forest of coniferous and broad-leaved trees (a typical forest type in Hokkaido, Japan) using landscape metrics and topographic factors, and attempted to apply this knowledge to examine forest management. This approach provides a new perspective (i.e., the landscape structure) on forest management, which traditionally has been determined on the basis of individual forest stands. We first created a cover type map of the study area by means of aerial photo interpretation. The characteristics of each cover type identified from the photographs were determined using landscape metrics for each cover class. We digitized a forest administrative map (1:20,000 scale) using 20-m contours, and imported this into GIS software to produce a terrain model; on this model, we overlaid the cover types. Our examination of landscape metrics showed that most of the natural forest could be managed similarly. However, our examination of topographic characteristics revealed exceptions (e.g., areas that are difficult to regenerate) that will require particular attention when managing the natural forest. Based on the information we obtained, we proposed a guideline for sustainable forest management. From the land cover map, we proposed an “improved” cover type map to illustrate the development of a high growing stock of forest based on forest management. We compared the current cover map with the “improved” cover map and demonstrated that the improved form would have more significant effects on fauna that do not recognize differences in the proportion of the dominant species types than on those that can recognize these differences. Our results show how the information obtained using landscape metrics and terrain models is an essential tool for various stages of forest management planning.  相似文献   

8.
以贵州省森林公园自然类景观资源为评价对象,对森林公园的生物、地文、水文、天象四大自然类景观资源进行了定性评价.结果表明,独具特色的喀斯特植被,多种多样的森林类型、繁多的珍稀植物种类等构成了丰富的生物景观资源;典型的喀斯特地貌以及独具特色的丹霞地貌景观等构成了地文景观资源;瀑布、泉、湖泊、水库等水文景观资源表现出清秀潋滟等特点;旭日朝晖、夕阳晚霞、苍山如海、云移峰动等天象景观丰富而绚丽.  相似文献   

9.
金沟岭林场森林景观分类及景观变化研究   总被引:7,自引:1,他引:7       下载免费PDF全文
以吉林省汪清林业局金沟岭实验林场为例,介绍了一种基于森林资源二类调查数据的森林景观类型划分方法。划分景观要素类型的因子一级为土地覆盖类型,二级为优势树种组。在景观分类的基础上分析了1987-1997年10a问金沟岭实验林场森林景观空间格局变化。1987年和1997年主要的景观要素类型为针阔混交林、针叶混交林、落叶松林和阔叶混交林,1987年的斑块个数为592块,1997年为946块。斑块个数大幅度增加,反映出森林景观破碎化的趋势。10a问,景观多样性指数和相对丰富度指数降低,优势度指数有所增加。文章对营林活动对森林景观变化的影响进行了初步分析,发现景观类型变化较大的林班也是作业强度比较大的林班,景观斑块数量变化最大的林班也是作业强度比较大的林班。  相似文献   

10.
黑龙江省林火规律研究Ⅱ.林火动态与格局影响因素的分析   总被引:19,自引:0,他引:19  
胡海清  金森 《林业科学》2002,38(2):98-102
本文对在大尺度 (5 0 0km2 以上 )上影响黑龙江省林火的因素及其影响途径进行了分析。结果表明 ,年林火次数 (人为火次数 )与林业人口正相关 ,林火面积与人口无关。干燥度的空间差异对林火燃烧率格局有正向影响。林火特征与气候因子之间没有线性关系。黑龙江省林火次数和面积对年均温和降水量的响应可归纳为旋转的单叶双曲面和双叶抛物面两种模式。林火特征的周期与年均温、年降水量的周期关系很大。黑龙江省森林类型对林火次数、面积的影响在省级区划尺度上不显著的。较高的管理水平显著减少林火。林火次数、面积与了望塔数量、消防车数量及通讯覆盖率等无线性关系  相似文献   

11.
Forest cover and land use change directly impact biological diversity worldwide, contribute to climate change and affect the ability of biological systems to support human needs by altering ecosystem services. Given the forest land use characteristics and ecosystem types in Luang Namtha Province, Lao PDR, the forest cover and land cover category of Luang Namtha Province were divided into six classes, i.e., current forest (CF), potential forest (PF), other wooded areas (OW), permanent agricultural land (PA), other non-forest areas (NF) and water (W). In first instance, earlier geographic information data (GIS data) of forest cover and land use during 1992 and 2002 was obtained from the Ministry of Agriculture and Forestry (MAF), Lao PDR. Two steps of forest land use change assessment were conducted by the MAF, i.e., plot sampling on satellite image maps (SIMs) to detect the changes of forest cover and land use during 1992 and 2002 for the entire Luang Namtha Province and field verification in order to identify causes of the changes. Secondly, dynamic information of the forest land cover changes during this ten-year period was calculated by means of map algebra in ArcGIS 9.2. Thirdly, based on the theory of ecosystem service functions and the service function values of different global ecosystems, the value of the six forest cover and land use categories in the province was obtained. Finally, ecological environmental effects, produced by the regional land cover changes over the study period, were calculated.  相似文献   

12.
福建省森林景观类型及地理分布概述   总被引:2,自引:1,他引:2  
福建省自然地理条件优越 ,生物多样性繁多 ,森林景观类型丰富。本文根据森林景观类型等级系统 ,将福建省森林景观划分为 10个森林景观组和 4 0多个森林景观型 ,概述了各类森林景观的不同特征及其地理分布状况 ,为全省森林旅游区划及合理改造和配置森林景观类型提供理论依据  相似文献   

13.
1IntroductionLandscapeisaregionconsistingofmanydifferenthetero-ecosystems.Theindividualeco-system抯structureandfunctionoflandscapewillchangeunderdifferentspatialandtemporalconditions,becausetheyareaffectedbyvariousfactors,suchasexchangeprocessofenergy,mattersandorganisms,biologicalandabiologicalactions,andhumanactivities.Landscapedynamicchangeisoneofthekeyresearchissuesoflandscapeecology(FormanandGodron1986,NavehandLiebermann1993,Sun1995).Itisgenerallyreflectedbyquantitativelyanalyzinglandsc…  相似文献   

14.
Central Rondônia is one of the most deforested regions in the Brazilian Amazon and contains areas at different stages of degradation forming a gradient from mature forest to highly urbanized and built-up areas. Regional data from satellite imagery are available from the 1980s, but apart from studies that quantify deforestation, the broad-scale landscape dynamics of Rondônia have not been examined well. This paper assesses the landscape changes between 1984 and 2002 in a watershed located in the central region of the state of Rondônia, Brazil, which has undergone systematic and rapid deforestation due to introduction of pasture that began in the 1970s. Bi-annual Landsat TM/ETM+ images from 1984 to 2002 were classified into three broad land cover types: mature forest, secondary forest, and pasture, resulting in a time series of land-use/land-cover maps. Landscape changes were evaluated by computing a cross tabulation between years, transition rates, and landscape metrics related to size, density, connectivity, configuration, and deforested patches distribution related to patch size and spatial proximity to roads and old pastures. Transition probability functions were fitted to the temporal series to predict land-use changes for the next 10 years, for three different scenarios: (1) continued land-use change; (2) eliminating clear-cutting and selective logging; and (3) eliminating clear-cutting, selective logging, and secondary vegetation clearing. Current land-use transitions cannot be sustained beyond the next 10–15 years. A more sustainable scenario for the region requires a major reduction of deforestation activities, implementing the “permanent preservation area” policy along riversides, and controlling land-use transitions at balanced levels. We recommend that forest managers in regions facing similar deforestation pressures should strive to maintain at least 35% mature or primary forest, because landscape fragmentation proceeds rapidly below this critical threshold.  相似文献   

15.
This paper addresses the effects of economic transition policies on forestry in China. The effects of de-collectivization and market liberalization on the forest land area and timber harvest are studied using panel data from four provinces covering the period 1978–1995. Fixed effects ordinary least squares models for forest land cover and annual harvests per hectare are estimated, allowing for differences across provinces and prefectures in northern and southern China. The results show that land tenure reform in general has had a positive effect on forest land expansion, but the absolute size of the effects varies from province to province. The positive impact of the reform on timber harvesting has not taken place at the cost of forest land cover. The claim that market liberalization leads to over-harvesting of forest resources in developing countries is not supported by our results.  相似文献   

16.
In Maine and other heavily forested states, existing land cover maps quickly become dated due to forest harvesting and land use conversion; therefore, these maps may not adequately reflect landscape properties and patterns relevant to current resource management and ecosystem studies. By updating an older land cover product (the 1993 Maine GAP map) using Landsat imagery and established forest change detection techniques, we demonstrate a practical and accurate means of providing contemporary, spatially explicit forest cover data needed to quantify landscape change. For a 1.8 million hectares study area in northern Maine, we quantify the accuracy of forest harvest classes and compare mapped harvest and regeneration area between the 2004 GAP update product and the 2004 Maine Landcover Dataset (MeLCD), a map recently developed in coordination with the 2001 National Land-Cover Database (NLCD). For the period 1995–2004, the overall harvest/non-harvest accuracy of the GAP update map is 87.5%, compared to 62.1% for the MeLCD. Producer and user accuracy for harvest detection is 92.4% and 89.7%, respectively for the GAP update, and 48.8% and 92.5% for the MeLCD. Mapped harvest area differs considerably, reflecting a systematic under-representation of recent harvest activity on the part of the MeLCD. By integrating older land cover data, the GAP update retains the forest disturbance legacies of the late 1970s through the early 1990s while simultaneously depicting 2004 forest composition for harvested and regenerating stands. In contrast, the MeLCD (and 2001 NLCD) over-represents the area and connectivity of older forest (undisturbed since the late 1970s), and provides no forest composition information for mapped forest regeneration. Systematic misclassification of forest age classes and harvest history has serious implications for studies focused on wildlife habitat modeling, forest inventory, and biomass or carbon stock estimation. We recommend the integration of older land cover data and time-series forest change detection for retention of harvest or disturbance classes when creating new forest and land cover maps.  相似文献   

17.
Forest landscape restoration (FLR) is a process that aims to regain ecological integrity and enhance human well-being in deforested or degraded forest landscapes. To ensure that restoration efforts are successful, the first step is to understand the dynamics of the forest landscape and the dominant forces responsible for its change. Taking Yong’an city, Fujian province in China as a case for study, this paper constructed a Markov model to predict the dynamics of the forest landscape based on sample-plot data of Continuous Forest Inventory at a county level. The study area was divided into eight landscape element types based on FLR, including approximated primary forest, secondary broad-leaved forest, secondary forest of Pinus massoniana, natural bamboo forest, planted forest, non-timber product forest, degraded forest land and non-forestry land. The analysis showed the following: (1) the extent of reforestation of planted forest, non-timber product forest and secondary forest of Pinus massoniana would be greater than that of deforestation of approximated primary forest, broad-leaved secondary forest and natural bamboo forest. Therefore, the total area covered by forest would increase steadily. (2) Conversely, conversion among different landscape element types would occur frequently and have high transition proportions. (3) Remarkable decrease of the extent of approximated primary forest, together with the conversion from degraded forest land to secondary forest, would probably result in the decline of forest volume. (4) Forest productivity in the meantime will not be maintained or enhanced because of the conversion from secondary forest to planted forest. These results suggest that the direct and underlying driving force of landscape dynamics should be understood and addressed in the upcoming studies for remnant approximated primary forest protection, secondary forest management and degraded forest land rehabilitation. The conclusion is that the Markov model can be used to analyze the forest landscape dynamics for FLR based on sample-plot survey data of Continuous Forest Inventory at a county level.  相似文献   

18.
Many studies have recently been devoted to the study of landscape change, and some have even focused on an analysis of the dynamics of forest cover change. However, few of the studies have worked on a methodology for making a detailed investigation of long-term forest change dynamics based on historic cartographic sources. The goal of this study is to further develop a method for analyzing long-term changes in forest cover on the basis of old maps and orthophoto maps in the GIS environment. The study area is located in Central Bohemia, to the east of Kutná Hora, a UNESCO World Heritage Site. The area consists of 21 cadastral units with a total area of 113 km2. The maps of the First (1780), Second (1851) and Third Military Surveys (1877) and the present-day orthophotomap (2007) of the Czech Republic were used as data resources. Source data have been processed in GIS. Forest cover is the subject of our study. However, the term is perceived from a broader perspective. What we call forest cover in our study refers to forest wood elements and other wood species in the landscape. In this study, forest cover has been structurally considered as a whole, without dividing it into the two categories mentioned. We counted the extent of the forest cover in each particular time horizon in hectares and as a percentage of the area under study, also the absolute changes in forest cover between the individual time horizons in hectares as well as the intensity of the changes in forest cover in hectares per year. The spatial changes in forest cover were evaluated in a GIS environment using specialized features to analyze spatial variation. The forest cover occupied 16.60% (1,880 ha) of the total area in the First Military Survey (1780). In 2007, the proportion was slightly higher at 16.64% (1,884 ha). More than half of all forest land (53%) from the time of the Second Military Survey (1851) survived until 2007. Not only the information on absolute changes but also the information on the rate of change is of great importance. The old Military Survey maps and the orthophotomap enable us to carry out studies of long-term changes in forest cover. However, the geodetic inaccuracy of the First Military Survey maps precludes reliable and exact quantification of the landscape changes between the First Military Survey and the Second Military Survey, and also between the First Military Survey and present-day (orthophoto map). These maps cannot be used for evaluating forest cover changes on the level of individual plots. The method presented in our paper may contribute to a better understanding of the long-term dynamics of forest land, covering a period of more than 250 years. This knowledge can be applied in forest management planning procedures. Apart from their application in forestry, the methods presented in this study may be of interest for historians and biologists.  相似文献   

19.
Forest communities across the landscape of the Central Hardwood Forest Region are experiencing a transition from dominance by oak (Quercus) and hickory (Carya) to maple (Acer) driven largely by a prolonged period of fire suppression. In many cases, this shift in community composition, structure, and function is considered undesirable as oak-hickory forests are valued for timber, wildlife habitat, and natural heritage. Considerable management and restoration efforts target the restoration of oak-hickory forest communities, yet treatments have yielded varying degrees of success. In some cases, difficulties in meeting targets may be due to ecological thresholds created by complex vegetation-environment interactions that maintain the maple-dominated community state. We examined direct and indirect interactions among vegetation layers and environmental gradients for the mature, second-growth forest communities of the Ironton Unit of the Wayne National Forest (WNF) in southeastern Ohio. Using a stratified random approach, we identified 72 study communities with trees at least 70 years old and without evidence of recent disturbance. Within these communities, we sampled all overstory vegetation on two-four 500 m2 plots and recorded saplings and ground-flora species in nested sub-plots. At each plot, we also collected soil samples for physical and chemical analyses and recorded physiographic variables. Our first objective was to describe the Ironton forest landscape, where communities were likely transitioning from oak to maple. To identify such patterns, we used ordination analyses that relate species occurrence to implied environmental gradients. Our second objective was to use the relationships to develop a structural equation model (SEM) to quantify the strength of pathways among the canopy, sapling, and ground-flora vegetation layers and environmental factors (e.g., soil chemistry and physiographic position). Our results indicate that the forest landscape of the Ironton Unit of the WNF is at a transition point with communities dominated by either oak or maple, and a sapling layer dominated by maple. Maple may be most likely to replace oak and hickory in the canopies of communities at mid- and lower-slope positions with intermediate soil moisture. This transition will likely have cascading effects throughout the sapling and ground-flora layers, which SEM demonstrates are directly influenced by the canopy. We believe the simultaneous consideration of direct and indirect interactions shaping vegetation structure and composition using techniques such as SEM will advance understanding of the current transition from an oak-hickory to a maple-dominated forest landscape. This information will contribute to the continued improvement of appropriate forest management and ecosystem restoration techniques for the Central Hardwood Forest Region, including those designed to shift the dominance of forest communities from maple to oak.  相似文献   

20.
White-tailed deer (Ododcoileus virginiana) can substantially affect the structure and species composition of a forest. The tolerance of a forest community to browsing may vary by type as a result of varying biotic and abiotic factors of the environment. To date, no studies have compared the effects of browsing among forest communities within a physiographic region. We investigated the effects of browsing on vegetation structure and woody seedling composition in three forest types (oak–hickory, Virginia pine–eastern red cedar, bottomland hardwood) in Manassas National Battlefield Park (MNBP), Virginia, USA. We compared forb cover, vertical plant cover (0–1.5 m tall), and survival of tagged seedlings in 10 exclosed (2 m × 6 m) and 10 unexclosed plots in each forest type during a 5-year period. No differential effects of browsing were found among forest types. In all forest types, deer (67 deer/km2) suppressed forb and vertical plant cover to levels less than would be expected in the absence of deer. Seedling survival rates of most species were significantly reduced by browsing. By the 4th year of the study, box elder (Acer negundo), hickory (Carya spp.), and red maple (Acer rubrum) had been eliminated from unexclosed plots, and red and white oaks (Quercus spp.) dramatically reduced. Ash (Fraxinus spp.), black cherry (Prunus serotina), and hackberry (Celtis occidentalis), although significantly impacted, remained the most abundant species throughout the study. These findings suggest that white-tailed deer may be modifying the structure of the forest interior to the extent that it adversely affects wildlife species dependent on a dense understory to thrive. We predict that the future composition of forests in MNBP will shift towards stands with fewer species and a greater dominance of ash, black cherry, and hackberry, particularly in the oak–hickory and bottomland hardwood forests, where the majority of current dominants are most affected.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号