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1.
The Chinese government applies the term ‘tree crops’ (jingjilin) to a bundle of tree species with uses other than timber production, defining this category as a component of national forest statistics. Tree crops may displace either farmland or forestland, and can be a promising livelihood option for smallholders. The overall impact of this particular policy on natural forest growth remained unanswered. In the general expansion trend of tree cover in southern China, tree crops could compete for land with natural forests, their cultivation may pose environmental trade-offs with natural forest cover. However, in a context of large labor flows from countryside to cities, tree crops could provide promising opportunities for dealing with on-farm labor shortages and generating income for disadvantaged populations remaining in rural communities, then promoting remaining natural forest quality through alternative livelihoods process. There is a knowledge gap to thoroughly investigate tree crops’ impact on natural forest change both conceptually and empirically, especially a mechanism verification of the alternative livelihood hypothesis. Thus, we construct a framework assessing land use competition and alternative livelihood effects together to assess overall impacts of tree crop cultivation on natural forests. Our dataset combines forest resource inventory data and provincial social-economic factors for a panel analysis of contributions to change in natural forest cover, density, and stock in China’s biodiversity-rich southern provinces. Results show tree crop cover is negatively associated with natural forest extent, but positive associated with change in natural forest density, while the relationship with change in natural forest stock is insignificant. Further tests of mechanisms support the hypothesis that tree crops benefit disadvantaged rural populations, providing an alternative livelihood. Defining tree crops as forest in China obscures important patterns, particularly a trade-off between tree crops and natural forest cover and a possible synergy with natural forest density mediated by alternative livelihood processes. Policy makers should enact specific policies to incentivize natural forest recovery in the southern collective forest zone and reconsider the appropriateness of defining tree crops as forest. Concentration and intensification of tree crop production on suitable lands may have the potential to benefit both forests and impoverished populations.  相似文献   

2.
Tropical deforestation and forest degradation are among the top global threats to biodiversity, carbon storage and rural livelihoods, but the social processes underlying these changes remain difficult to observe across large spatial scales and in data-poor contexts such as tropical Africa. We link longitudinal survey data from agricultural households in rural Uganda to high-resolution satellite data on forest cover change, and use this linked dataset to investigate processes at two scales: tree planting and harvesting at the parcel scale, and deforestation and reforestation at the community scale. This multi-scale analysis reveals that tree planting is more common on parcels with secure tenure, by educated heads and in isolated communities. Deforestation is highest in land-rich, agrarian communities with low population density and high baseline forest cover. These results provide explicit evidence that the social drivers of forest change in Uganda vary across scales, indicating a need for additional multi-scale studies.  相似文献   

3.
Strict enforcement of forest protection and massive afforestation campaigns have contributed to a significant increase in China's forest cover during the last 20 years. At the same time, demographic changes in rural areas due to changes in reproduction patterns and the emigration of younger population segments have affected land-use strategies. We identified proximate causes and underlying drivers that influence the decisions of farm households to plant trees on former cropland with Bayesian networks (BNs). BNs allow the incorporation of causal relationships in data analysis and can combine qualitative stakeholder knowledge with quantitative data. We defined the structure of the network with expert knowledge and in-depth discussions with land users. The network was calibrated and validated with data from a survey of 509 rural households in two upland areas of Yunnan Province in Southwest China. The results substantiate the influence of land endowments, labor availability and forest policies for switching from cropland to tree planting. State forest policies have constituted the main underlying driver to the forest transition in the past, but private afforestation activities increasingly dominate the expansion of tree cover. Farmers plant trees on private incentives mainly to cash in on the improved economic opportunities provided by tree crops, but tree planting also constitutes an important strategy to adjust to growing labor scarcities.  相似文献   

4.
Most industrial countries have experienced a transformation of land use: from decreasing to expanding forest areas, the so-called forest transition. Outside closed forests, European rural landscapes exhibit a diversity of tree-based agricultural systems, but the question of whether this forest transition has also affected ‘trees outside forests’ has rarely been studied. The aim of this study is to analyze the spatial-temporal dynamics of farm trees and woodlands in an agricultural landscape in Eastern Germany from 1964 to 2008, based on aerial photographs and digital orthophotos. Taking a landscape ecological perspective, we quantify farm tree dynamics, disentangle processes of gain and loss in the socialist and post-socialist periods of Eastern Germany, and assess differences in ecosystem services provided by farm trees. A substantial increase of overall tree cover by 24.8% was observed for the selected time period, but trajectories have been disparate across different farm tree classes. The increase in tree cover was stronger in steep valleys than on hills and plateaus, indicating a significant interdependence between topography and trajectories of change. Patch numbers of farm trees did not increase, which suggests that the expansion of tree cover is mostly due to a spatial expansion of previously existing tree patches. Overall net gains in tree cover were rather similar during the socialist and post-socialist eras. The general increase in tree cover was accompanied by increase in agriculture-related ecosystem service provision, but the increase in pollination and pest control services was much lower than that in water purification services. These findings present the first empirical evidence from an industrialized country that there is also an ongoing ‘forest transition’ outside closed forests. Potential, partially counteracting drivers of change during the socialist and post-socialist periods have mainly been related to farm policies and the environmental consciousness of land users and society as a whole.  相似文献   

5.
One of the main causes of tropical forest loss is conversion to agriculture, which is constantly increasing as a dominant land cover in the tropics. The loss of forests greatly affects biodiversity and ecosystem services. This paper assesses the economic return from increasing tree cover in agricultural landscapes in two tropical locations, West Java, Indonesia and eastern Bangladesh. Agroforestry systems are compared with subsistence seasonal food-crop-based agricultural systems. Data were collected through rapid rural appraisal, field observation, focus groups and semi-structured interviews of farm households. The inclusion of agroforestry tree crops in seasonal agriculture improved the systems’ overall economic performance (net present value), even when it reduced understorey crop production. However, seasonal agriculture has higher income per unit of land area used for crop cultivation compared with the tree establishment and development phase of agroforestry farms. Thus, there is a trade-off between short-term loss of agricultural income and longer-term economic gain from planting trees in farmland. For resource-poor farmers to implement this change, institutional support is needed to improve their knowledge and skills with this unfamiliar form of land management, sufficient capital for the initial investment, and an increase in the security of land tenure.  相似文献   

6.
目的 研究“退耕还林”“退牧还草”及“镰刀弯”等生态政策实施以来西辽河流域植被覆盖时空变化趋势及驱动因素,探究各类驱动因子对区域植被覆盖的影响,为区域生态建设和环境保护提供参考。方法 文章采用像元二分模型,估算西辽河流域植被覆盖度,归纳了植被覆盖变化的驱动因素,利用一元线性回归和Pearson相关系数等方法,定性定量分析2000—2018年西辽河流域植被覆盖时空变化趋势及其与气候、地形、农村居民点分布和土地利用变化等驱动因子的响应关系。结果 19年来,西辽河流域植被覆盖度呈波动增加趋势。分区看,农区植被覆盖度最高,其次是半农半牧区,牧区植被覆盖度最低。全区植被覆盖空间变化趋势较为稳定,96.63%面积植被覆盖无明显变化,2.07%面积植被覆盖极显著改善,1.30%面积植被覆盖显著改善,基本无退化区域。结论 (1)植被覆盖度与降水、气温因子正向相关,降水对植被覆盖度的影响高于气温。(2)高程、坡度和农村居民点密度均与植被覆盖度正向相关,其中农区人类农业种植活动正向促进作用要大于生产建设活动的负向抑制作用。(3)林地和作物种植面积长势的增加促进了全区植被覆盖的改善。“退耕还林”和“镰刀弯”生态实施促进了全区植被覆盖的改善,但“退牧还草”生态工程效益有待提高。应注重区域植被覆盖变化监测与预警,充分发挥生态政策的积极导向作用,优化生态工程实施结构,提高生态脆弱区抵御风险能力。  相似文献   

7.
The Central American Dry Corridor (CADC) is a trans-border region characterized by climatic and ecological continuities. It is expected to experience rising aridity and severe hydro-climatic events due to climate change. Subsistence agriculture and other rural livelihoods to which land cover is central are widely practiced in this impoverished territory of approximately eleven million people.The CADC’s land cover was profiled to determine: a) how it differs from Non-CADC areas, and b) the role of land use in shaping these differences. Spatial autocorrelation analysis using satellite data showed that forest cover is a third less prevalent in the CADC than in the Non-CADC while the share of mosaic vegetation and mosaic cropland is nearly double. A naturally prevalent cover type in the CADC, tropical dry forest (TDF), has been largely eliminated.The significantly lesser proportion of forest and greater percentage of coverage consistent with agriculture and ranching implicate land use conversion, specifically deforestation for agricultural expansion and cattle ranching, in shaping CADC land coverage. The process began in the mid-1800s when small-scale agriculturalists migrated to the region followed by large-scale export crop and beef production, primarily for international markets. Deforestation peaked after WWII, concluding by the 1990s with the conversion of most woodlands. Similar patterns now threaten forests along the Caribbean coast.Traditional land use practices cannot sustain local communities or preserve the resource base, thereby contributing to rural outmigration. Adopting sustainable practices and promoting livelihoods strategies leading to forest regeneration will be fundamental for CC adaptation in the CADC.  相似文献   

8.
Recent land cover change estimates show overall decline of tropical forests at the regional and global scales caused by multiple social, cultural and economic factors. There is an overall concern on the prevailing land use practices, such as shifting cultivation and extraction of forest materials as agents of forests losses, but also new, emerging land uses are threatening tropical forests. Understanding of the long-term development and driving forces of forest changes are needed, especially at local levels where many decisions on forest policies and land uses are made. This paper addresses the importance of such information for improved estimates of forest dynamics by studying local level land cover and land use changes during the last 50–70 years in the Eastern African tropical island of Zanzibar, Tanzania. The paper discusses the role of traditional and new land uses mainly subsistence farming, tourism and government interference through tree planting, in the long-term development of the forests at the village level. The material for the study is gathered from the interpretation of archival maps and aerial photographs combined with contemporary digital aerial photographs. The analyses are based on the mapping, spatial sampling and spatio-temporal change trajectory analysis (LCTA) of forest land cover, forest land uses and settlement patterns with GIS and statistics. Six distinct forest land cover change trajectories were identified and these illustrate dynamic and heterogeneous nature of the forests. Closed forest cover has dominated throughout due to cyclical land use patterns, but over 70% of the land area has been continuously transforming between closed, semi-open and open land cover conditions. Land use turnover rates indicate that hardly any forest areas are left untouched from the forces, which remove and re-establish forest vegetation in the long run. Land cover and land use change trajectories are spatially fragmented in the studied landscape. Majority of forest loss-gain dynamics is caused by shifting cultivation, while forest losses are most dramatic along the coast, where traditional and new land uses meet and land uses pressures are highest. The study suggests that landscape change trajectory analyses, where contemporary and historical information on land uses and land cover changes are spatially linked, can provide valuable aspects into local level forest land use planning and management strategies. For the case study, the findings suggest the following key forest management strategies for consideration: (1) establishment of a protected forest/scrubland in participation with the local stakeholders, especially the farmers, (2) promotion of areas for permanent agricultural practices, while simultaneously introducing management controls in the traditional slash-and-burn farming areas, and (3) promoting new livelihood opportunities for the farmers, who have traditionally been dependent on forest resources, meanwhile introducing alternatives for fuel wood for cooking.  相似文献   

9.
This project examines the relationship between migration, population, and economic processes, and forest cover change in Mexico from 2001 to 2010. Using multiple regression analyses with remotely-sensed, significant (p < 0.10) change in woody vegetation from 2001 to 2010 as our dependent variable, we explore how environmental, migration, demographic, and economic indicators at the national and sub-national biome scales are associated with forest cover change. Results highlight the importance of international migration in forest cover change, demonstrating that international (and internal) migration processes should also be included in LU/CC research and deforestation policy.  相似文献   

10.
Exurban communities—a significant form of urban sprawl—can transform natural land cover. Exurban development refers to an expansion of communities located outside a city and its suburbs. One of the main reasons these settlements develop is a desire by residents to live closer to nature and developers’ recognition of the profitability of addressing this desire. Additionally, exurbs can become prosperous regions settled by people with high income. However, exurban development not only directly affects community patterns, but also species patterns, habitat reduction and disconnection, as well as land cover and land use alterations. The purpose of this paper is a quantitative analysis of the land cover transformation and forest fragmentation in Post-Soviet Russia, based on an empirical case study of the city of Kurgan. This case study also contributes to the overall research of urban sprawl in Russian provinces by adding to the discussion of homeowners’ behavior, regional environmental policies, and their role concerning the impacts of exurban settlements on the natural environment. This paper uses remote sensing imagery, census data, and primary data to analyze land cover change due to the emergence of exurban communities around Kurgan, Russia, with specific emphasis on the changes to native vegetation resulting from human behavior and stakeholder preferences.  相似文献   

11.
甘肃省酒泉市近年来经济发展迅速,但生态环境也遭到一定程度的破坏;拟通过对其土地利用和覆盖变化的研究,为环境保护与经济协调发展提供决策支持;依据肃州区1988~2000年土地利用变更调查数据,对该区域LUCC进行分析,确定了土地利用类型的转移概率矩阵,并用马尔柯夫链模型预测了该区LUCC趋势。结果表明,肃州区土地利用将呈现耕地、水域和建设用地增加,林地、草地和未利用土地减少的发展趋势。  相似文献   

12.
Human societies constantly interact with the environment through mutual feedbacks and adaptations. The aim of this research was to analyze human and environmental dimensions so as to understand how the dynamic processes of land use and land cover change are contributing to the increase of forest cover observed between 1985 and 2011 in the Paraíba Valley, Brazil. The forestry sector, based on eucalyptus plantations, is given particular attention due to its role in these change processes. Multi-layer perception neural network (MPNN) models were adopted to evaluate the influence of independent variables in the process of the forest transition. Based on the model's results, we conclude that the process is conditioned by a set of biophysical and socioeconomic variables that operate during different historical periods and in different landscape settings. The proximity of Atlantic forest remnants was influential in the forest transition for the three periods analyzed: 1985–1995, 1995–2005, and 2005–2011. In the first period of change (1985–1995), topography was most influential. Between the periods of 1995–2005 and 2005–2011, the proximity to eucalyptus plantations was an important factor, indicating a high probability of native forest recovery occurring in the vicinity of these monocultural areas. The forest transition tends to occur in areas less suitable for agriculture at the outset, but as these areas are replaced by forest cover, socioeconomic drivers such as farm credit and economic development play important roles in forest recovery.  相似文献   

13.
Research on the dynamics of tropical forest land use and cover change (LUCC) has focused on the three scenarios: (1) deforestation/degradation; (2) settled, degraded areas in recovery, and (3) sparsely settled, expansive, intact forest. Through examination of a central Quintana Roo, Mexico case study we propose a fourth scenario of a ‘sustainable landscape’: an inhabited, productively used, forested landscape that nonetheless shows little change or net gains in forest cover over the last 25 years. We use Landsat images to demonstrate a low incidence of net deforestation, 0.01% for the 1984–2000 period, the lowest recorded deforestation rate for southeastern Mexico. Institutional innovations such as an agrarian reform process that established large common property forests for non-timber forest product extraction, and later innovations such as sustainable forest management institutions have driven the outcome of low net deforestation, added to multiple organizational processes that promote sustainable land use.  相似文献   

14.
Humans have altered land cover for centuries, and land-cover change is a main component of global change. Land use transition trajectories, such as the forest transition theory (i.e. switch from deforestation to stable or increasing forest cover), relate long term changes in land use to gradual changes in underlying drivers, such as economic development, demographic change, and urbanization. However, because only few studies examined land change over centuries, it is not clear how land cover changes during very long time-periods which are punctuated by shifts in socio-economics and policies, such as wars. Our goal here was to examine broad land change patterns and processes, and their main driving forces in Central and Eastern Europe during distinct periods of the past 250 years. We conducted a meta-analysis of 66 publications describing 102 case study locations and quantified the main forest and agricultural changes in the Carpathian region since the 18th century. These studies captured gradual changes since the peak of the Austro-Hungarian Empire up to the accession to the European Union of most of the formerly socialist countries in the study region. Agricultural land-use increased during the Austro-Hungarian Empire in 70% of the case studies, but dropped sharply during and especially after the collapse of the Socialism (over 70% of the cases). The highest rates of abandonment occurred between 1990 and 2000. The Carpathian region experienced forest transition during the Interwar period (93% of the cases), and the forest expansion trend persisted after the collapse of Socialism (70% of the cases). In terms of the drivers, institutional and economic factors were most influential in shaping deforestation and agricultural expansion, while socio-demographics and institutional shifts were the key drivers of land abandonment. Our study highlights the drastic effects that socio-economic and institutional changes can have on land-use and land-cover change, and the value of longitudinal studies of land change to uncover these effects.  相似文献   

15.
Systematic conservation planning (SCP) seeks to propose new reserves through a scientifically rigorous process using databases and research selection algorithims. However, SCP exercises have been criticized for “knowing but not doing”, i.e. not implementing the proposed reserve. But there is an additional problem that can be called “knowing but not knowing”, knowing things from databases, but not knowing crucial contextual information about community-based social processes that have supported the high forest cover and biodiversity detected. Examined here is how a common property region of the Sierra Norte of Oaxaca, Mexico has maintained high forest cover in the absence of public protected areas, while multiple SCP exercises have advocated for the creation of public protected areas in communal tropical montane cloud forests and pine forests as strategies for biodiversity conservation and resilience to climate change. Methods included archival research, review of community documents, focus group interviews, semi-structured interviews, participant observation, land use transects, and GIS analysis and remote sensing. Conservation in the region originally occurred because of low population densities, steep slopes and a lack of agricultural subsidies, supported by locally adapted agricultural practices. In the 1990s, a transition from passive to active conservation took place with land use zoning plans, community conservation rules, community forestry enterprises and payments for environmental service programs that consolidated a trend towards high, unthreatened forest cover. Today, the study communities have an average of 88.3% forest cover, with 61% of that in informal conservation based on community land use zoning and rules and another 14% governed by forest management plans approved by the Mexican government. We argue that truly systematic conservation plans would seek to understand how communities in the region are already managing forests for conservation. It is pointless and uninformed to advocate for top-down conservation interventions of forests that are already robustly conserved and resilient to climate change due to community action.  相似文献   

16.
Prevention and mitigation of the progressive spread of artificialization are key goals of environmental protection policies leading to the establishment of protected areas. Artificialization processes can be effectively assessed by analyzing land cover and land use changes, which put in evidence different kinds of processes that spur a decrease in natural areas and an increase in artificial ones. In this article, we first analyze land cover change processes by developing transition matrices using the simplified Land and Ecosystem Account taxonomy, and next we compare and contrast processes that take place in areas characterized by different levels of environmental protection, which we identify as follows: natural protected areas, sites of the European Natura 2000 network, and unprotected areas. We take the Italian island of Sardinia as a case study, since a system of national and regional parks and an extensive Natura 2000 network have been established in this region, and analyze and compare land cover change processes over more than twenty years (i.e. between 1990 and 2012). Our results highlight significant implications for the definition and implementation of planning policies aiming at preventing or mitigating artificialization processes within the island. However, the methodological approach here proposed can be applied in other European regional contexts so as to tailor planning policies to the local characteristics of ongoing land cover transition processes.  相似文献   

17.
Desertification and land degradation are worldwide problems affecting soil, vegetation and the livelihoods of rural populations. Bowal (plural bowé) is a particular form of degraded land that occurs in tropical regions and leads to the exposure of ferricretes, which are unsuitable for farming. Bowé are more common on farmland and degraded savanna. Changes in land use/land cover were used to map a region of 6.7 million ha in northern Benin, West Africa in 1975, 1990 and 2010. The changes observed during these periods (1975–1990, 1990–2010 and 1975–2010) were used to predict the occurrence of bowé in the period up to 2050 using Markovian chain analysis. The results showed a considerable change in land use/land cover during the three periods. The types of land on which bowé occur (farmland and degraded savanna) increased in northern Benin by 5.4% per year during the period 1975–1990 and 9.5% per year during the periods 1990–2010, while the natural vegetation (forest, woodland and tree savanna) decreased by the same amount. The future scenarios also predicted the same trend. In the period 1975–1990, 1.28 million ha (26%) of natural vegetation was converted to degraded savanna and farmland while 2.23 million ha (53%) of natural vegetation was converted to degraded savanna and farmland in the period 1990–2010. Based on the dynamics recorded during the period 1975–1990 and 1990–2010 respectively, a total of 1.28 million ha (26% of the natural vegetation that was present in 1975) and 1.29 million ha (31% of the natural vegetation that was present in 1990) will be converted to farmland and degraded savanna in the study area by 2050.Thus bowalization will persist and increase in the period up to 2050. The natural vegetation could disappear if protection and restoration measures are not taken. It is thus important to take measures to stop the degradation and to implement programs to restore soils on bowé based on the soil and water conservation techniques used on highly degraded West African soils, such as zaï pit and stone rows with grass strips. Some native plants species adapted to bowalization and resistant to climate change in northern Benin (e.g. Asparagus africanus, Andropogon pseudapricus and Combretum nigricans) should be used in association with soil and water conservation techniques on bowé.  相似文献   

18.
基于Radarsat 2全极化数据的多种雷达植被指数差异分析   总被引:1,自引:0,他引:1  
[目的]雷达植被指数(Radar Vegetation Index,RVI)作为评价雷达影像植被分布与生长状态的重要指标,对植被生长动态监测具有重要意义。然而,不同算法的雷达植被指数对于同一地物类型的表征往往存在一定的差异。文章通过对比分析3种常用RVI在多种类型地物上的差异,为其在SAR影像特征提取、分类、识别等应用提供指导性意见。[方法]实验基于武汉市Radarsat-2全极化数据,结合Google earth历史影像和实地调研数据,选取林地、灌丛、草地、耕地、水生植被、建筑、道路、裸地、湖泊、河流10种典型地物样本,从样本折线图分布、类内标准差等方面,对分别通过H/A/alpha分解、Freeman分解和后向散射系数计算得到的3种常用雷达植被指数Van_RVI、Freeman_RVI和Kim_RVI进行了测算分析。[结果] 3种雷达植被指数有着相似的折线图走势,对植被的监测能力良好,但对于不同地物的敏感性稍有差异:Freeman_RVI对林地等高密度植被区域敏感程度较高; Van_RVI对耕地与林地、灌木与林地具有一定的区分性; Kim_RVI对水体与建筑的敏感程度较高。[结论] Freeman_RVI对高密度植被识别能力最好,可用于林地提取、森林制图; Van_RVI对植被与非植被的区分能力最好,适用于植被提取; Kim_RVI数据预处理计算速度最快,但提取精度不高,可用于应急制图。  相似文献   

19.
The role of land tenure and Mennonites as drivers of deforestation in the Central Yucatan Peninsula has not been empirically assessed. We evaluate different drivers and their relationship to forest cover change between 1986 and 2015 and assess how land tenure and Mennonite communities impact forest cover loss in the Municipality of Hopelchen, Campeche, Mexico. This study shows that forest cover loss has increased in the last decade (2005–2015), and that land tenure regime type is associated with this loss. Throughout the study period, statistical comparisons show rates of forest cover loss were significantly higher in private and federal property compared to forests in ejidos (communal property). Forest cover loss in Mennonite private property was also significantly higher than in non-Mennonite owned private property. The role of land tenure and the expansion of the agroindustrial production model as major drivers of forest cover loss in the region provide important insight into developing municipal land use plans and conservation strategies to reduce deforestation. Programs, incentives and policy directed towards forest conservation in the region that typically target ejido communities, will need to consider the growing trend of private property expansion within federal lands and work more closely with private property owners including Mennonite communities if deforestation reduction programs are to be successful.  相似文献   

20.
We model Central American migrant-sending household agricultural practices given labor losses and the concomitant infusion of remittances. Under the new economics of labor migration (NELM) framework, it is hypothesized that smallholder farm households invest remittance income in their land either to increase crop production or to transition to cattle ranching. We test this hypothesis by developing a combination of multivariate logistic, Poisson and beta regression techniques using Latin American Migration Project data to determine how agricultural land use change compared among migrant and non-migrant households in Costa Rica, El Salvador, Guatemala, and Nicaragua. Results indicate that a rise in months spent abroad and remittances returned do not translate into a higher percentage of farm sales, intensification or transition to cattle ranching – counter to NELM. However, farmers are investing remittances to increase row crop and pasture land holdings. These findings suggest remittance investments in quantitative increase rather than qualitative change in land use practices. Given the expansive land demands supporting low intensity smallholder agriculture and cattle, and the land degradation cattle precipitate particularly, the trend does not augur well for the sustainability of rural landscapes increasingly transformed by international remittances. Appropriate policies to champion coupled human-land system sustainability in Central America might usefully consider viable land use alternatives to remittance investments dedicated to crop and pasture expansion.  相似文献   

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