Land‐use legacies in a central Appalachian forest: differential response of trees and herbs to historic agricultural practices

Question: Are contemporary herb and tree patterns explained by historic land use practices? If so, are observed vegetation patterns associated with life‐history characteristics, soil properties, or other environmental variables? Location: Southeastern Ohio, USA. Methods: Using archival records, currently forested sites were identified with distinct land use histories: cultivated, pasture (but not plowed), and reference sites which appear to have never been cleared. Trees were recorded by size and species on twenty 20 m × 20 m plots; percent cover was estimated for each herb species in nested 10 m × 10 m plots. Environmental characteristics were noted, and soil samples analysed for nutrient availability and organic matter. Nonmetric multidimensional scaling ordination was performed separately on both tree and herb datasets to graphically characterize community composition among plots. Life‐history traits were investigated to explain observed compositional differences. Results: Vegetation patterns were explained by current environmental gradients, especially by land‐use history. Cultivated and pasture sites had similar tree composition, distinct from reference sites. Herb composition of pasture and reference sites was similar and distinct from cultivated sites, suggesting the ‘tenacity’ of some forest herbs on formerly cleared sites. Tilling removes rhizomatous species, and disfavors species with unassisted dispersal. These life‐history traits were underrepresented on cultivated sites, although ant‐dispersed species were not. Conclusions: Historic land‐use practices accounted for as much variation in species composition as environmental gradients. Furthermore, trees and herbs responded differently to past land‐use practices. Life‐history traits of individual species interact with the nature of disturbance to influence community composition.     

An integrated reconstruction of recent forest dynamics in a New England cultural landscape

Broad-scale patterns of vegetation response to three centuries of human disturbance in the northeastern United States are well understood, but stand-scale (0.1–10 ha) interactions between land-use history and the ecological processes underlying these patterns are not. Enduring legacies of land-use history, though pervasive in modern forests, are not always obvious or intuitive, particularly in the regenerating stands that cover most of the region. Focusing on a second-growth, post-agricultural landscape in Petersham, Massachusetts, this study integrates (i) a stand-scale sedimentary pollen and charcoal record, (ii) survey and dendroecological data from the surrounding forest, and (iii) analysis of historical documents describing site-specific ownership and land use history. We demonstrate the strength of this multifaceted approach to vegetation reconstruction on sites with long land-use histories that are typical of the modern landscape. We infer that periods of low and high intensity agriculture commenced around 1760 and 1850, respectively, and that the agricultural era was initiated and terminated by episodes of increased fire. Dendroecological data corroborate deed records and suggest that a portion of the forest regenerated and was used for small-scale timber production during the mid to late 1800s. Most of the forest established in the early 1900s, after which time the greatest disturbance was Cryphonectria parasitica (chestnut blight) induced mortality of Castanea dentata (American chestnut) and replacement by Betula (birch) species. This study highlights the potential to expand integrated historical ecological research into landscapes with lengthy histories of human disturbance and underscores the potential of this research to generate data with spatial and temporal resolution relevant to management and conservation efforts.     

Persistent land-use legacies increase small-scale diversity and strengthen vegetation–soil relationships on an unmanaged heathland

Land-use legacies are recognized determinants of vegetation dynamics and plant community assembly. The duration of these legacies and how they influence the structure of vegetation communities developing naturally in nutrient-poor ecosystems is not well understood. Here, we focus on the effects of increased nutrient availability from previous agricultural practices on multiple vegetation properties in a heathland where agriculture and domestic grazing ceased near 1870 and 1895, respectively. We compared diversity, compositional and functional properties of the vegetation responses to land-use legacies in the soil between areas with different agricultural histories (previously cultivated vs. uncultivated). Diversity measures were found to be higher in the previously cultivated soils. β-diversity was mainly driven by changes in species relative cover and increased with increasing nutrient availability in the cultivated area. Furthermore, functional traits related to nutrient acquisition (SLA and Leaf Nitrogen content) and the changes in vegetation composition were directly linked to soil properties only in the previously cultivated part of the heathland. Together these results revealed a shift to a deterministic control of the plant community, where increased nutrient availability leads to stronger associations between soil and vegetation properties. This suggests that as nutrients become available, niche differentiation and competitive interactions become the predominant underlying mechanisms structuring the community. Our study shows that land-use legacies of moderate intensity can alter the assembly mechanisms and diversity patterns in unmanaged vegetation that can be maintained after more than a century since cessation of agricultural practice. Identifying land-use legacies and understanding how they structure heathland communities can thus lead to management decisions adapted to the specific assembly mechanisms and result in a more effective management.     

Vegetation patterns in heterogeneous landscapes: The importance of history and environment

Abstract. Throughout the eastern United States, plant species distributions and community patterns have developed in response to heterogeneous environmental conditions and a wide range of historical factors, including complex histories of natural and anthropogenic disturbance. Despite increased recognition of the importance of disturbance in determining forest composition and structure, few studies have assessed the relative influence of current environment and historical factors on modern vegetation, in part because detailed knowledge of prior disturbance is often lacking. In the present study, we investigate modern and historical factors that control vegetation patterns at Harvard Forest in central Massachusetts, USA. Similar to the forested uplands throughout the northeastern United States, the site is physiographically heterogeneous and has a long and complex history of natural and anthropogenic disturbance. However, data on forest composition and disturbance history collected over the past > 90 years allow us to evaluate the importance of historical factors rigorously, which is rarely possible on other sites. Soil analyses and historical sources document four categories of historical land use on areas that are all forested today: cultivated fields, improved pastures/mowings, unimproved pastures, and continuously forested woodlots. Ordination and logistic regressions indicate that although species have responded individualistically to a wide range of environmental and disturbance factors, many species are influenced by three factors: soil drainage, land use history, and C:N ratios. Few species vary in accordance with ionic gradients, damage from the 1938 hurricane, or a 1957 fire. Contrary to our expectation that the effects of disturbance will diminish over time, historical land use predicts 1992 vegetation composition better than 1937 composition, perhaps because historical woodlots have become increasingly differentiated from post-agricultural stands through the 20th century. Interpretations of modern vegetation must consider the importance of historical factors in addition to current environmental conditions. However, because disturbances such as land use practices and wind damage are complex, it is often difficult to detect disturbance effects using multivariate approaches, even when the broad history of disturbance is known.     

Historic land use influences contemporary establishment of invasive plant species

The legacy of agricultural land use can have widespread and persistent effects on contemporary landscapes. Although agriculture can lead to persistent changes in soil characteristics and plant communities, it remains unclear whether historic agricultural land use can alter the likelihood of contemporary biological invasions. To understand how agricultural land-use history might interact with well-known drivers of invasion, we conducted factorial manipulations of soil disturbance and resource additions within non-agricultural remnant sites and post-agricultural sites invaded by two non-native Lespedeza species. Our results reveal that variation in invader success can depend on the interplay of historic land use and contemporary processes: for both Lespedeza species, establishment was greater in remnant sites, but soil disturbance enhanced establishment irrespective of land-use history, demonstrating that contemporary processes can help to overcome legacy constraints on invader success. In contrast, additions of resources known to facilitate seedling recruitment (N and water) reduced invader establishment in post-agricultural but not in remnant sites, providing evidence that interactions between historic and contemporary processes can also limit invader success. Our findings thus illustrate that a consideration of historic land use may help to clarify the often contingent responses of invasive plants to known determinants of invasibility. Moreover, in finding significantly greater soil compaction at post-agricultural sites, our study provides a putative mechanism for historic land-use effects on contemporary invasive plant establishment. Our work suggests that an understanding of invasion dynamics requires knowledge of anthropogenic events that often occur decades before the introduction of invasive propagules.     

Environmental causes and consequences of forest clearance and agricultural abandonment in central New York, USA

Aim Climate, topography and soils drive many patterns of plant distribution and abundance across landscapes, but current plant communities may also reflect a legacy of past disturbance such as agricultural land use. To assess the relative influences of environmental conditions and disturbance history on vegetation, it is important to understand how these forces interact. This study relates the geographical distribution of land uses to variation in topography and soils; evaluates the consequences of land‐use decisions for current forests; and examines the effects of agricultural land use on the chemical properties of forest soils. Location Tompkins County occupies 1250 km² in central New York's Finger Lakes region. Like much of eastern North America, this area underwent forest clearance for agriculture during the 1800s and widespread field abandonment and forest recovery during the 1900s. The current landscape consists of a patchwork of forests that were never cleared, forests that developed on old fields and active agricultural lands. Methods We investigated relationships among topography, soils and land‐use decisions by gathering information about land‐use history, slope, aspect, elevation, soil lime content, soil drainage and accessibility in a geographic information system (GIS). To assess the effects of agriculture on forest soil chemistry, we measured pH, organic matter content and extractable nutrient concentrations in field‐collected soil samples from 47 post‐agricultural and uncleared forests. Results Steeper slopes, less accessible lands and lower‐lime soils tended to remain forested, and farmers were more likely to abandon fields that were steeper, farther from roads, lower in lime and more poorly drained. Slope had by far the greatest impact on patterns of clearance and abandonment, and accessibility had a surprisingly strong influence on the distribution of land uses. The effects of other factors varied more, depending for example on location within the county. Current forest types differed accordingly in topography and soil attributes, particularly slope, but they also showed much overlap. Post‐agricultural and uncleared forest soils had similar chemical properties. Forests on lands abandoned from agriculture 80–100 years before had slightly higher pH and nutrient concentrations than adjacent, uncleared forests, but these changes were small compared to environmental variation across the county. Main conclusions Despite differential use of lands according to their topography and soils, the substantial influence of accessibility and the relatively small scale of land‐use decisions allowed for broad similarity among forest types. Thus, the topography and soil differences created by land‐use decisions probably contribute little to landscape‐level patterns of diversity. Subtle changes in forest soil chemistry left from past agriculture may nevertheless affect plant distribution and abundance at finer scales.     

Land use designation and vegetation community structure in the Adirondack uplands (New York,USA)

Question: Does forest vegetation community structure reflect legislative land use designations? Location: Adirondack Park, New York, USA. Methods: The Adirondack Park, located in northern New York State, is a mixture of public and private lands, with state‐owned Forest Preserve lands comprising ca. 42% of the 2.4 million ha, on which timber harvesting and many other forms of anthropogenic disturbance are prohibited. A survey of vegetation communities was conducted in eighteen upland catchments with differing land use history (managed and Forest Preserve), including overstory, understory, and dead wood (snags and downed woody debris) using randomly placed plots. Results: Mean overstory density and basal area were not significantly different between land uses, although mean overstory tree size was greater in Preserve catchments. Sapling densities were greater in managed catchments, while mean herb/shrub coverage was not affected by land use. Densities of 25% of common species were affected by land use, determined by GIS coverages constructed using an Inverse Distance Weighted estimation procedure. Discriminant Analysis of per‐plot plant community data correctly classified 89% of both managed and Preserve plots. Conclusion: The success of the Discriminant Analysis in classifying land uses based on vegetation communities indicates its potential utility of this method in comparing forest vegetation to a reference condition in this and other areas. The analysis suggests that at least 85 years is required for Adirondack up‐land catchments to recover following harvesting. Uncertainty in classification was related to heterogenous management and disturbance patterns within catchments.     

Vegetation dynamics of Mediterranean shrublands in former cultural landscape at Grazalema Mountains,South Spain

Plant community dynamics in Mediterranean basin ecosystems are mainly driven by an alternation of episodes of human intervention and land abandonment. As a result, a mosaic of plant communities has evolved following different stages of degradation and regeneration. Some authors has relate secondary succession to abandoned culture lands and regeneration to natural systems with abandonment of livestock or forestry exploitation. In this paper, the dynamics of shrublands in mid-mountain areas in the South of Spain after disturbance and land abandonment has been studied. The plant cover and 13 environmental variables of 137 selected sites on the Grazalema mountains was analysed to determine the vegetation pattern in relation to environmental factors and the succession types, either regenerative or secondary succession. The results show that today the Grazalema mountains have a heterogeneous vegetation pattern. Besides physical factors such as altitude or soil , human disturbance has modulated current vegetation patterns and dynamics. Two main types of vegetation dynamics can be distinguished in the study area. In areas affected by cutting, regeneration results in rich and dense shrub land, with resprouters as dominant species. In areas affected by recurrent wildfires or agriculture, secondary succession became dominant, resulting in less diverse shrubland, due to the dominance of seeders and decrease in resprouter species richness and cover.     

Slow recovery in desert perennial vegetation following prolonged human disturbance

Questions: How long may it take for desert perennial vegetation to recover from prolonged human disturbance and how do different plant community variables (i.e. diversity, density and cover) change during the recovery process? Location: Sonoran Desert, Arizona, USA. Methods: Since protection from grazing from 1907 onwards, plant diversity, density and cover of perennial species were monitored intermittently on ten 10 m × 10 m permanent plots on Tumamoc Hill, Tucson, Arizona, USA. Results: The study shows an exceptionally slow recovery of perennial vegetation from prolonged heavy grazing and other human impacts. Since protection, overall species richness and habitat heterogeneity at the study site continued to increase until the 1960s when diversity, density and cover had been stabilized. During the same period, overall plant density and cover also increased. Species turnover increased gradually with time but no significant relation between any of the three community variables and precipitation or Palmer Drought Severity Index (PDSI) was detected. Conclusions: It took more than 50 yr for the perennial vegetation to recover from prolonged human disturbance. The increases in plant species richness, density, and cover of the perennial vegetation were mostly due to the increase of herbaceous species, especially palatable species. The lack of a clear relationship between environment (e.g. precipitation) and community variables suggests that site history and plant life history must be taken into account in examining the nature of vegetation recovery processes after disturbance.     

Land-Use History as Long-Term Broad-Scale Disturbance: Regional Forest Dynamics in Central New England

Human land-use activities differ from natural disturbance processes and may elicit novel biotic responses and disrupt existing biotic-environmental relationships. The widespread prevalence of land use requires that human activity be addressed as a fundamental ecological process and that lessons from investigations of land-use history be applied to landscape conservation and management. Changes in the intensity of land use and extent of forest cover in New England over the past 3 centuries provide the opportunity to evaluate the nature of forest response and reorganization to such broad-scale disturbance. Using a range of archival data and modern studies, we assessed historical changes in forest vegetation and land use from the Colonial period (early 17th century) to the present across a 5000 km² area in central Massachusetts in order to evaluate the effects of this novel disturbance regime on the structure, composition, and pattern of vegetation and its relationship to regional climatic gradients. At the time of European settlement, the distribution of tree taxa and forest assemblages showed pronounced regional variation and corresponded strongly to climate gradients, especially variation in growing degree days. The dominance of hemlock and northern hardwoods (maple, beech, and birch) in the cooler Central Uplands and oak and hickory at lower elevations in the Connecticut Valley and Eastern Lowlands is consistent with the regional distribution of these taxa and suggests a strong climatic control over broad-scale vegetation patterns. We infer from historical and paleoecological data that intensive natural or aboriginal disturbance was minimal in the Uplands, whereas infrequent surface fires in the Lowlands may have helped to maintain the abundance of central hardwoods and to restrict the abundance of hemlock, beech, and sugar maple in these areas. The modern vegetation is compositionally distinct from Colonial vegetation, exhibits less regional variation in the distribution of tree taxa or forest assemblages defined by tree taxa, and shows little relationship to broad climatic gradients. The homogenization of the vegetation, disruption of vegetation-environment relationships, and formation of new assemblages appear to be the result of (a) a massive, novel disturbance regime; (b) ongoing low-intensity human and natural disturbance throughout the reforestation period to the present; (c) permanent changes in some aspects of the biotic and abiotic environment; and (d) a relatively short period for forest recovery (100–150 years). These factors have maintained the regional abundance of shade intolerant and moderately tolerant taxa (for example, birch, red maple, oak, and pine) and restricted the spread and increase of shade-tolerant, long-lived taxa such as hemlock and beech. These results raise the possibility that historical land use has similarly altered vegetation-environment relationships across broader geographic regions and should be considered in all contemporary studies of global change. Received 5 May 1997; accepted 5 August 1997.     

新疆玛纳斯河流域2000-2010年土地利用/覆盖变化及影响因素

在2000年和2010年两期遥感影像解译的基础上,从土地利用类型的结构、变化速率、变化方向及土地利用程度等方面分析了玛纳斯河流域土地利用的变化特征,并分析了影响土地利用变化的主要因素及不同因素之间的交互作用。结果表明:(1)近10年来,流域土地利用程度增强,人工绿洲呈扩张趋势,耕地和城乡工矿居民用地大量增加,林地和未利用地减少;上游地区草地和冰川积雪覆盖地面积增加。(2)耕地向内部外部双向扩张,主要来源于林地、荒漠和盐碱地;新增草地以山地裸地和山前荒漠的转变为主;林地主要转变为中游的耕地和城乡工矿居民用地及上游的草地和裸地;城乡工矿居民用地的增加主要来自荒漠、耕地和林地;未利用地变化以向人工绿洲土地类型的转变为主。(3)上游土地利用变化主要受气候变化的影响,降水量增加可能是冰川积雪面积扩张的主要原因;中游人类活动密集,耕地和城乡工矿居民用地扩张,荒漠植被退化;下游受气候和人类活动共同作用,尾闾湖泊萎缩,河岸和湖周植被退化。     

Effects of natural and anthropogenic gradients on native and exotic winter annuals in a southern California Desert

Native annual plant species constitute a large proportion of the plant diversity found in arid vegetation types within the southwestern United States; yet, little is known about controls on diversity patterns along natural and anthropogenic gradients. In this study we evaluated native species richness and exotic species cover across overlapping gradients of precipitation, wind, and N deposition in the Colorado Desert of southern California. Factors allowing native diversity to persist under high N deposition and high wind were also evaluated in a second, focused study at one end of the gradient. We found that gradients in precipitation, nitrogen deposition, and wind were the most important factors to native richness and exotic species cover across the landscape, while local heterogeneity in bare ground influenced richness and cover at the high deposition/windy, or high-disturbance, end of the gradient. Patterns of native diversity were evaluated across the gradients using non-metric multidimensional scaling, which showed diversity was split into two axes: one strongly correlated to precipitation and the other strongly correlated with disturbance factors. The disturbance factors were also positively associated with exotic grass and forb cover. In total, these results indicate that large-scale patterns in disturbance and exotic species cover negatively affect native annual plant species diversity but native species can also persist due to local heterogeneity.     

The application of multivariate land classification to vegetation survey in the Wicklow Mountains,Ireland

Multivariate land classification and land cover mapping by aerial photographic interpretation were used to model spatial variation of land cover in the Wicklow Mountains, Ireland and to structure a stratified random sampling programme of upland blanket bog vegetation. The total area of blanket bog with gully-erosion features was estimated as 33% of the area studied. Vegetation with hand peat-cutting patterns was estimated at 5%, and there was 35% undissected (intact) vegetation. There were differences between land classes in the estimated area of land cover with gully-erosion features or hand peat-cutting patterns.Sample vegetation quadrats, stratified by land class and aerial photographic land cover type, were grouped by their plant species composition. The groups represented ombrotrophic mire, soligenous mire and shrub heath vegetation. There was significant association between vegetation group and land class, related to variation in regional landscape type, but no significant association between vegetation group and the aerial photographic land cover types, undissected (intact) and dissected (gullied and cut-over) peats. It is proposed that the similarity of vegetation between undissected and dissected blanket bog is related to vegetation regeneration. The need to consider differences in vegetation distribution, composition and dynamics in ecological management strategies is emphasised. The study demonstrated the value of stratified random field sampling for cost-efficient regional ecological assessment in upland blanket bog landscapes typified by the Wicklow mountains, Ireland.     

喀斯特地区坡耕地与退耕地土壤有机碳空间异质性及其影响因素

利用网格采样(10 m×10 m),对比分析了典型喀斯特坡耕地(长期耕作)和退耕地(自然恢复)表层(0—15 cm)土壤有机碳(SOC)的空间变异特征,以期探究退耕恢复20a后SOC的空间异质性及其主要影响因素的变化。结果表明退耕地SOC含量(75.5 g/kg)显著高于坡耕地(15.1 g/kg),为坡耕地的5.0倍,说明自然恢复能显著提高SOC累积量;半变异函数分析结果表明退耕地基台值(521.7)为坡耕地(25.7)的14.9倍,说明退耕地SOC空间异质性远大于坡耕地。坡耕地和退耕地SOC的主要影响因子存在较大差异,土地覆盖类型、坡位、岩石出露率以及三者的交互作用显著控制着坡耕地SOC的空间格局,其贡献率分别为9.1%、6.3%、4.6%以及17.0%;土壤水分、坡度、岩石出露率以及三者的交互作用显著控制退耕地SOC的空间格局,其贡献率分别为26.0%、10.7%、7.2%以及3.6%;尽管岩石出露率对坡耕地和退耕地SOC的空间格局均有显著影响,但坡耕地SOC的主要控制因子为土地覆盖类型以及各因子的交互作用,而退耕地的主要控制因子为土壤水分。以上研究表明随着植被恢复和物种多样性增加,喀斯特坡地SOC的累积量和空间异质性增强,自然因素对SOC空间格局影响凸显,而岩石出露率始终控制SOC空间格局。     

京津冀地区城市化对植被覆盖度及景观格局的影响

定量研究了2000—2010年,京津冀地区植被覆盖度及其景观格局的动态变化,揭示了城市化进程对植被景观的干扰过程及生态质量的影响。结果表明:(1)2000—2010年,城市化进程显著是京津冀城市群土地变化的一大特点,人工表面面积从2000年的1.79×10~4km~2增加至2.16×10~4km~2,增幅高达21.16%;(2)京津冀平均植被覆盖度呈增加趋势但不显著(P=0.46),存在明显的时空动态差异。在覆盖度结构上形成了以中低和中植被覆盖度为主导的格局;(3)从景观空间格局变化来看,中低、高覆盖度区域植被景观更加破碎,而低、中等覆盖度区域的植被面积增加,景观破碎度减小;尤其是低植被覆盖度为主的城市区域,景观格局变化幅度大,表现为绿地面积有所增加,景观破碎化程度降低,生态质量有所改善;(4)在整个研究区范围,城市化对区域植被覆盖度存在负面影响,表现为城市化程度与区域平均植被覆盖度存在负相关(P=0.08);但是在低植被覆盖度的区域(主要为城市区域),城市化程度与植被覆盖面积呈显著正相关(P0.001),表明城市区域在城市化进程中植被覆盖面积有所提高,生态质量有所改善,与城市化过程中,日益重视城市绿地的建设有关。     

Evaluation of the Degraded Riparian Ecosystems in the Geum River Watershed in Korea

Riparian vegetation, an important mediator of land–water interactions, provides habitat for animals and other organisms; however, riparian vegetation zones have been altered by agricultural and urban development in Korea. This riparian vegetation survey was conducted to obtain information vital for the ecological restoration and management of the Korean Geum River ecosystem. At 100 study sites, along the Geum River, we recorded the vegetation of the Geum riparian zone. We then surveyed the riparian vegetation associations in the area and overlaid those areas corresponding to trees, shrubs, perennial herbs, annual herbs, exotic plants, cultivated lands, and damaged lands on a geographical map. We also reconstructed the cross-sectional landscape. The mean values of vegetation diversity, exotic plant area (%), annual plant area (%), and species richness were 6.47 ± 0.26, 5.44 ± 1.01, 11.98 ± 1.20, and 22.69 ± 0.93, respectively. The landscape elements of the herbaceous plants were more spread out, compared with those of the woody plants, and 23 sites were composed strictly of herbs. Our results indicate significant differences in vegetation structure among the study sites. For example, at some sites, exotic plants, cultivated lands, and damaged lands dominated the landscape comprising 25.7, 62, and 68.9%, respectively, of the area. The riparian landscape reference model suggested by these results may be applied to studies of other well-conserved riparian zones. We propose that the material pathways and transport of organisms from land to water at Geum River depend on the patchy distribution of these diverse landscape elements.     

Plant Community Recovery Following Restoration in Semiarid Grasslands

The Conservation Reserve Program (CRP) is an extensive land use in the United States, which restores cultivated land to perennial vegetation through seeding. Low precipitation and high potential evapotranspiration are major limitations to the establishment and growth of seeded species in semiarid regions. We tested the rate of development of plant functional types across a chronosequence of restored fields using a model of plant succession. We also determined how the seeding of non‐native (introduced) relative to native perennial grasses influenced plant community recovery. In contrast to the native shortgrass steppe (SGS), recently seeded CRP fields had high cover of annuals, forbs, C₃, and introduced species. The seed mix determined which perennial grasses dominated the plant community within 18 years, but slow establishment prolonged early seral stages, allowed for the spread of colonizing perennial grasses, and limited recovery to less than half the canopy cover of undisturbed shortrass steppe. Species density declined in restored fields as seeded perennial grass cover increased and was lower in CRP fields seeded with introduced compared to native perennial grasses. Plant community composition transitioned to C₄ and native species, even if fields were not seeded with these species, and was modified by shifts in the amount and seasonality of precipitation. Thus, in semiarid CRP fields, we found that the potential for recovery depended on time since CRP enrollment, seed mix, and climatic variability. Full recovery, based on similarity to vegetation cover and composition of undisturbed SGS, requires greater than 20 years.     

Traditional Livelihoods,Conservation and Meadow Ecology in Jiuzhaigou National Park,Sichuan, China

Jiuzhaigou National Park (JNP) is a site of global conservation significance. Conservation policies in JNP include the implementation of two national reforestation programs to increase forest cover and the exclusion of local land-use. We use archaeological excavation, ethnographic interviews, remote sensing and vegetation surveys to examine the implications of these policies for non-forest, montane meadows. We find that Amdo Tibetan people cultivated the valley for >2,000 years, creating and maintaining meadows through land clearing, burning and grazing. Meadows served as sites for gathering plants and mushrooms and over 40 % of contemporary species are ethnobotanically useful. Remote sensing analyses indicate a substantial (69.6 %) decline in meadow area between 1974 and 2004. Respondents report a loss of their “true history” and connections to the past associated with loss of meadows. Conservation policies intended to preserve biodiversity are unintentionally contributing to the loss of these ecologically and culturally significant meadow habitats.