Differences in land cover interpretation in landscapes rich in cover gradients: reflections based on the <Emphasis Type="Italic">montado</Emphasis> of South Portugal

This paper contributes to the discussion on current issues in methodologies of mapping land cover in the agro-silvo-pastoral landscapes of the Mediterranean. These landscapes, characterized by intermixed land use and indefinite boundaries, require particular attention in applying the patch-corridor-matrix model when classifying patches and their delineation. In a case study area in southeast Portugal, mainly characterized by agro-silvo pastoral systems, the land cover for 1990 has been mapped. The paper discusses the consequences of the complexity of some Mediterranean land use systems for land cover mapping dealing with detailed landscape dynamics. Within this scope a land cover mapping project in a small case study area is compared with the mapping undertaken within a national land cover database. Both studies were carried out on the same scale and through visual interpretation of aerial photographs. Differences in land cover classification and allocation are explored using matrix with levels of agreement. Recommendations for future land cover mapping projects are: the application of fuzzy approaches to land cover mapping in agro-silvo-pastoral landscapes should be explored and land cover classifications should be standardized in order to enhance consistency between databases. On the other hand, the fuzziness of the boundaries in this kind of landscapes is inherent to the system and should be accepted as such. The accompanying uncertainties should be taken into account when undertaking landscape analysis on the basis of land cover data.     

文峪河流域土地利用/覆被变化及其驱动力分析

土地利用/覆被变化对于区域的自然、经济和生态发展有着深刻的影响,土地变化驱动力研究是土地利用/覆被变化的核心问题之一。为了探讨中西部小流域的土地覆被变化特征及其驱动因子组成与驱动方式,以山西省文峪河流域为研究对象,基于RS与GIS平台,分析流域2000—2018年土地利用/覆被变化情况;利用马尔柯夫模型预测未来土地利用结构;选取自然因子、区位建设因子、社会经济因子,利用Logistic回归的建模方法分析流域的土地利用/覆被驱动力。结果表明,流域整体耕地、林地、草地面积有所减少,水域、建设用地、其他用地类型面积增加,不同地类的变化速度、土地转移情况不同,流域整体土地变化速度较快,利用程度提高,有序化程度下降,均匀度增加。预测结果显示,耕地、林地、草地、其他用地面积下降,水域、建设用地面积增加,除耕地、建设用地外,其余地类面积变化较小。自然因子、区位建设因子和社会经济因子对研究区土地利用/覆被变化都具有显著的驱动作用。流域的土地利用/覆被在过去18年间经历了快速、复杂的变化,自然因子对土地变化具有基础性、长远性的影响,短时间尺度上区位建设因子与社会经济因子是影响土地变化的主要驱动力量。     

应用遥感图片对西班牙Guadalteba地区灌木土地退化的评估

自然(资源)土地覆盖信息对分析和理解当前的陆地形式,尤其是对面临着环境日益恶化的研究区起着重要的作用。本研究综合应用Aster遥感数据和现地实际情况,完善西班牙Guadalteba地区2001年的土地覆盖图,将精度从47％提高到70％。综合土地覆盖图反映了该地区的植物类型分布和目前的自然(资源)土地覆盖状况。基于该图,自然(资源)土地覆盖图显示了自然(资源)和农业用地的当前分布,灌木土地退化图表明了各种灌木区的分布位置及其退化的不同等级,并作了进一步分析和讨论。最终的成果图揭示,Guadalteba地区许多以灌木分布为主导形式的土地已经被改用为农业和其他用途用地。由于人类活动的干扰而导致该地区大部分土地退化,使灌木覆盖仅占约9％的土地面积。图4表3参8。     

Changes of forest land use and ecosystem service values along Lao-Chinese border: A case study of Luang Namtha Province, Lao PDR

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.     

衡阳盆地土地利用/覆盖变化及模拟

以2003年、2013年两期森林资源二类调查小班数据以及2009年森林资源年度更新数据为基础,提取出衡阳盆地2003、2009、2013年三期土地利用/覆盖数据,在IDRISI17.0软件支持下,利用提取出的矢量数据进行空间叠加运算,得出土地利用/覆盖类型空间转移矩阵,分析了2003—2013年间衡阳盆地土地利用/覆盖类型的面积变化和结构变化情况。现状结果显示:2003—2013年,衡阳盆地内草地、林地和未利用地面积均有下降,耕地、建设用地、园地和水域面积均有所增加。基于CA-Markov模型模拟出2023年土地利用/覆盖情景。模拟出2023年衡阳盆地的土地利用/覆盖情景,并依据数量Kappa系数、位置Kappa系数和标准Kappa系数检验模拟精度。模拟结果显示:2013—2023年间,衡阳盆地内的林地将向草地、耕地和水域转化,耕地则更多的转化为园地和未利用地,部分林地、耕地和水域将继续向建设用地转换。     

国际土地利用与土地覆盖变化对生态环境影响的研究

土地利用与土地覆盖变化作为全球变化的一个重要内容,对全球生态环境产生了巨大的影响,一方面通过影响气候、土壤、水文以及地貌而对自然环境产生了深刻的影响,另一方面则造成了生态系统的生物多样性、物质循环与能量流动以及景观结构的巨大变化,使得生态系统的结构和功能发生了改变。文中介绍了国际上土地利用与土地覆盖变化对生态环境影响的最新研究进展,并对相关研究在未来的发展进行了探讨。     

Deforestation and loss of bushland and grassland primarily due to expansion of cultivation in mainland Tanzania (1995–2010)

Information on land use and cover changes (LUCC) is important for planning of conservation and development and thus ensure forest sustainability. The current paper assesses LUCC for the whole of the mainland Tanzania. The analyses were done using land use and cover maps covering the whole of mainland Tanzania for 1995 and 2010. For 1995, forest, bushland, grassland, cultivation and other land use and cover (built up areas, bare land, etc.) covered 43.5%, 19.8%, 23.5%, 11.2%, and 2.0% of the study area, respectively. For 2010, the same land use and cover classes covered 38.0%, 14.5%, 6.9%, 36.5%, and 4.1% of the study area, respectively. The annual rate of deforestation was 320,067 ha, which is equivalent to 0.9%. Bushland and grassland were lost at 313,745 and 969,982 ha/year, respectively. Most forest was converted to cultivation and least to other land use and cover. In conclusion, the net changes were deforestation and loss of bushland and grassland primarily due to expansion of cultivation. Further research on how to reduce or halt expansion of cultivation may shed light on improving sustainability of forest, bushland, and grassland in mainland Tanzania.     

Land use/land cover change dynamics and drivers in a low-grade marginal coffee growing region of Veracruz,Mexico

In the state of Veracruz, Mexico, lowland and marginal coffee growing regions have been particularly vulnerable since the 1989 coffee crisis. Government programs have promoted production diversification as a strategy to improve local incomes and conserve environmentally beneficial shade-tree coffee agroforests. We present results on land use/land cover dynamics in the municipality of Zozocolco de Hidalgo from 1973 to 2006. The municipality is recognized for its indigenous population and poverty, and currently, diversification efforts are being implemented. Our study combines remote sensing and GIS analyses, binary logistic regression and econometric modeling, as well as socioeconomic surveys to evaluate land use/land cover change (LULCC) dynamics and explore potential environmental and socioeconomic drivers. Results show that tree cover and coffee agroforests had largely been conserved during the first decade after the coffee crisis. But, recent trends indicate loss of tree cover in coffee agroforests and their conversion mostly to pasture. Land use/land cover drivers are largely explained by spatially explicit environmental variables such as slope and elevation. Relevant socioeconomic variables such as distance to markets and land use profitability were not significantly related to land use changes in Zozocolco. Surveys revealed that many households had converted coffee agroforests to pasture or agriculture in the past decade and others intended on renting or selling their agroforest plots, mostly for conversion to pasture. Diversification programs may not be sufficient to stem deforestation in lowland and marginal coffee growing regions. Moreover, information about locally varying socioeconomic and cultural contexts needs to be strongly considered in order to formulate effective strategies.     

我国土地利用动态预测与模拟研究新进展

指出了随着土地利用/覆被变化研究的深入和3S技术的发展,土地利用变化的预测和模拟研究取得了很大的进展,涌现出许多建模方法,有力地推动了土地利用/覆被变化研究的发展。通过对典型性研究进行梳理,总结了近年我国在这一领域的研究状况和存在的一些问题,并对发展方向进行了展望,以期为该领域研究提供参考。     

Characterizing changes in land cover and forest fragmentation from multitemporal Landsat observations (1993-2018)in the Dhorpatan Hunting Reserve,Nepal

Natural forces and anthropogenic activities greatly alter land cover,deteriorate or alleviate forest frag-mentation and affect biodiversity.Thus land cover and forest fragmentation dynamics have become a focus of concern for natural resource management agencies and biodiversity con-servation communities.However,there are few land cover datasets and forest fragmentation information available for the Dhorpatan Hunting Reserve (DHR) of Nepal to develop targeted biodiversity conservation plans.In this study,these gaps were filled by characterizing land cover and forest frag-mentation trends in the DHR.Using five Landsat images between 1993 and 2018,a support vector machine algorithm was applied to classify six land cover classes:forest,grass-lands,barren lands,agricultural and built-up areas,water bodies,and snow and glaciers.Subsequently,two landscape process models and four landscape metrics were used to depict the forest fragmentation situations.Results showed that forest cover increased from 39.4％ in 1993 to 39.8％ in 2018.Conversely,grasslands decreased from 38.2％ in 1993 to 36.9％ in 2018.The forest shrinkage was responsible for forest loss during the period,suggesting that the loss of for-est cover reduced the connectivity between forest and non-forested areas.Expansion was the dominant component of the forest restoration process,implying that it avoided the occurrence of isolated forests.The maximum value of edge density and perimeter area fractal dimension metrics and the minimum value of aggregation index were observed in 2011,revealing that forests in this year were most fragmented.These specific observations from the current analysis can help local authorities and local communities,who are highly dependent on forest resources,to better develop local forest management and biodiversity conservation plans.     

Impacts of Deforestation and Land Cover Change on Mountain Soils in Hrazdan,Armenia

The impacts of deforestation and land cover change upon underlying soils were examined on one hillside in central Armenia. Soil characteristics in three land cover areas—forest, coppice, and pasture—were recorded and soil samples were analyzed. Deforestation and land cover change were found to increase erosion rates. From soil horizon and structural characteristics, it can be estimated that 40 cm of soil have been lost in the pasture and 20 cm have been lost in the coppice compared to the forest. Soil organic carbon was also affected by deforestation and land cover change. Compared to the forest (4.7% organic carbon), both the coppice (3.7%) and the pasture (3.4%) had lower values. Phosphorus, potassium, and nitrogen content varied and may have been affected by erosion, animal deposition, differing amounts of vegetative residues present, differing organic matter decomposition rates, and differing hydrological processes. Deforestation was also found to change the species composition of seedlings and saplings in the coppice in comparison to the forest, reducing oak numbers and increasing hornbeam recruitment.     

Inclusion of forest harvest legacies, forest type, and regeneration spatial patterns in updated forest maps: A comparison of mapping results

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.     

生态毯覆盖对若尔盖沙化草地土壤环境及植被恢复的影响

为遏制若尔盖草原沙化进一步蔓延,急需开展草地沙化治理模式研究.试验选取若尔盖草原半固定沙地和流动沙地为研究对象,分析了生态毯覆盖对两种沙地类型土壤环境、植物群落盖度和生物量的影响.结果表明:生态毯覆盖1 a后,有效提高了沙地植物群落盖度和生物量,流动沙地中生态毯覆盖的群落盖度和生物量较对照处理的增量高于半固定沙地,半固定沙地生态毯覆盖的群落盖度和生物量分别是对照处理的1.20倍和1.19倍,而流动沙地则分别为对照的4.74倍和2.83倍;生态毯覆盖均降低了两种类型沙地的土壤温度,增加了土壤水分,提高了土壤最大持水量;生态毯覆盖对两种类型沙地土壤电导率的改善效果一致,均比对照高0.01 ms·cm-1;半固定沙地中生态毯覆盖和对照处理的土壤容重相同,流动沙地中生态毯覆盖的土壤容重较对照处理低0.02 g·cm-3;生态毯覆盖初期对流动沙地的恢复效果优于半固定沙地.生态毯覆盖对土壤环境指标的影响均未达到显著水平,可能是由于试验年限较短所致.     

内蒙古沙漠化土地概况及发展变化分析

内蒙古沙漠化土地面积占总土地面积的 2 6.5% ,沙漠化土地分布范围涉及 8盟 4市 76个旗 (县、区 )。沙漠化土地面积仍在扩大 ,但速度明显减缓 ,且固定和半固定沙地所占比例明显上升     

Impact of human and environmental factors on land cover changes of an oak silvopastoral system

Silvopastoral systems integrate the complexity of forestry and forage-livestock management in an economically and ecologically sustainable way. However, these systems have undergone intensive pressure over the past decades caused by changes in land uses, as well as, in local socioeconomic priorities that suppressed traditional practices such as livestock grazing. These changes have caused land cover spatiotemporal diversifications whose effects were investigated in a traditional oak silvopastoral system at western Greece. In order to investigate the effect of human activities over the study area, the spatiotemporal land cover changes in conjunction with human and animal population changes and the environmental factors altitude, soil depth, inclination and rock type were analyzed. Also, forest-crown density changes were examined as a complimentary factor for the investigation of human intervention in the study area. Data about land-cover changes were derived from aerial orthorectified photographs of years 1945 and 2008, complimented by maps of environmental factors. Data digitization was implemented by the use of ArcGis. Based on the data analysis it derives that land cover changes are mainly attributed to direct human intervention. Environmental factors affect the ecosystem in two ways; first by affecting the location, type and intensity of human activities in the area, for example, soil depth determines where land is more productive and so predetermines the location, type and intensity of agricultural activities. Secondly, in the areas without or with minimal human intervention, environmental factors affect directly the land cover in conjunction with natural species necessities and their antagonistic capabilities.

     

Impacts of economic reforms on rural forestry in China

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.     

Effects of changes in land use and land cover on sediment discharge of runoff in a typical watershed in the hill and gully loess region of northwest China

Land use plays a much more important role than other factors, such as climate, soil properties, topographic features, vegetation coverage, human activities and others, in affecting soil erosion and sediment discharge. In order to understand the effects of changes in land use on sediment discharge and to provide a theoretical basis for land use planning, management and ecological restoration, we used the controlled Qiaozidong watershed and the uncontrolled Qiaozixi watershed in the third sub-region of the Loess Plateau as examples and analyzed the effects of land use and land cover on the discharge of sediments. The results show that the impact of land use and land cover on the annual amount of sediment discharge is significant. Compared with the uncontrolled watershed during similar periods, the amount of sediment discharged from the controlled watershed was reduced by 44%, 75% and 86%, respectively, in wet, normal and dry years. In the controlled watershed, compared with the period from 1986 to 1994, the amount of sediments discharged was less during the period from 1995 to 2004. The impact of land use and land cover on sediment discharge demonstrated characteristics of seasonal fluctuation. The effects of sediment reduction in the controlled watershed were greater than those in the uncontrolled watershed in May and September. In the controlled watershed, the reduction effect coincided with the distribution of rainfall. The amount of discharged flood sediments is closely correlated with rainfall, rainfall intensity in a 60 min period and the volume of flood. The rainstorm-runoff process and the rainstorm-sediment discharge process demonstrate that land cover has a strong regulatory and control function in the flood process and sediment discharge in rainstorms. For the controlled watershed, given the same precipitation frequency distribution, the average amount of sediment discharged during the land use period from 1995 to 2004 was less than that during the earlier land use period from 1986 to 1994 under every recurrent period. __________ Translated from Journal of Beijing Forestry University, 2007, 29(6): 115–122 [译自: 北京林业大学学报]     

基于ETM＋影像融合的土地覆盖分类研究——以蓬安县为例

借助ERDAS软件,运用遥感数据融合技术对四川省蓬安县进行基于ETM＋融合影像的土地覆盖分类初步研究。研究中采用相同的训练样本区及最大似然法分类方法,对融合前后影像分别进行土地覆盖分类,通过对分类影像的Producers Accuracy,Users Accuracy,Kappa Accuracy三者的精度数据对比分析,上述的影像融合方法对提高土地覆盖分类的精度较为明显;就3种融合方法及重采样方式而言,乘积法融合法和立方卷积重采样法相对更为可取。     

Effects of roads,topography, and land use on forest cover dynamics in the Brazilian Atlantic Forest

Roads and topography can determine patterns of land use and distribution of forest cover, particularly in tropical regions. We evaluated how road density, land use, and topography affected forest fragmentation, deforestation and forest regrowth in a Brazilian Atlantic Forest region near the city of São Paulo. We mapped roads and land use/land cover for three years (1962, 1981 and 2000) from historical aerial photographs, and summarized the distribution of roads, land use/land cover and topography within a grid of 94 non-overlapping 100 ha squares. We used generalized least squares regression models for data analysis. Our models showed that forest fragmentation and deforestation depended on topography, land use and road density, whereas forest regrowth depended primarily on land use. However, the relationships between these variables and forest dynamics changed in the two studied periods; land use and slope were the strongest predictors from 1962 to 1981, and past (1962) road density and land use were the strongest predictors for the following period (1981–2000). Roads had the strongest relationship with deforestation and forest fragmentation when the expansions of agriculture and buildings were limited to already deforested areas, and when there was a rapid expansion of development, under influence of São Paulo city. Furthermore, the past (1962) road network was more important than the recent road network (1981) when explaining forest dynamics between 1981 and 2000, suggesting a long-term effect of roads. Roads are permanent scars on the landscape and facilitate deforestation and forest fragmentation due to increased accessibility and land valorization, which control land-use and land-cover dynamics. Topography directly affected deforestation, agriculture and road expansion, mainly between 1962 and 1981. Forest are thus in peril where there are more roads, and long-term conservation strategies should consider ways to mitigate roads as permanent landscape features and drivers facilitators of deforestation and forest fragmentation.     

National Forest Policy in India: Critique of Targets and Implementation

For any country, the forest policy is an important guideline to maintain forest resources and their interaction with other land uses. India devised its first National Forest Policy (NFP) back in 1894. There has been a paradigm shift from timber production to forest conservation followed by community-based agroforestry and social forestry bringing a change in perspective towards forest resources. This change has been socio-economic, cultural and ecological. Since the 1952 NFP, there has been an advocacy for 33% forest cover with a 60% forest cover in mountainous and hilly regions. This objective was reiterated in the NFP 1988 and also confirmed in the National Forestry Commission report in 2006. This paper reviews the probable reasons for these targets. This paper also analyzes forest cover trends at state level and assesses the likelihood of meeting the prescribed policy targets under present perspective of land use practices. Only three Indian states meet the prescribed policy, while three more have the potential to do so, if their state wasteland area is afforested. Among the rest, a few states may achieve the 33% goal provided land conversion to tree cover is not hindered, and adequate resources are available at state level. The Planning Commission (XI Five-year Plan, 2007–12) has emphasized inclusion of other natural ecosystems (including treeless areas and trees outside forests) to forest cover. The paper also examines the above prescribed targets in light of the Planning Commission recommendations. It is argued that that the NFP should be re-visited and revised to meet the targets, along with setting a more realistic and attainable target for Indian forest and tree cover.