Decision tree classification of land cover from remotely sensed data

Decision tree classification algorithms have significant potential for land cover mapping problems and have not been tested in detail by the remote sensing community relative to more conventional pattern recognition techniques such as maximum likelihood classification. In this paper, we present several types of decision tree classification algorithms arid evaluate them on three different remote sensing data sets. The decision tree classification algorithms tested include an univariate decision tree, a multivariate decision tree, and a hybrid decision tree capable of including several different types of classification algorithms within a single decision tree structure. Classification accuracies produced by each of these decision tree algorithms are compared with both maximum likelihood and linear discriminant function classifiers. Results from this analysis show that the decision tree algorithms consistently outperform the maximum likelihood and linear discriminant function classifiers in regard to classf — cation accuracy. In particular, the hybrid tree consistently produced the highest classification accuracies for the data sets tested. More generally, the results from this work show that decision trees have several advantages for remote sensing applications by virtue of their relatively simple, explicit, and intuitive classification structure. Further, decision tree algorithms are strictly nonparametric and, therefore, make no assumptions regarding the distribution of input data, and are flexible and robust with respect to nonlinear and noisy relations among input features and class labels.

Coupling of seagrass (Cymodocea nodosa) patch dynamics to subaqueous dune migratio

The coupling between patch dynamics - described by the patch growth (horizontal and vertical), patch mortality, and life-history of Cymodocea nodosa (Ucria) Aschers., and the disturbance caused by the migration of subaqueous dunes over the plants was examined in a shallow NW Mediterranean bay (Alfacs Bay) where this species maintains a patchy cover. C. nodosa shoots survived substantial burial rates (up to 2.4 mm/day) by growing vertically at rates proportional to, albeit four-fold slower than, burial rates. Patch death was caused by erosion as large subaqueous dunes migrated pass the plant patch. Patch growth was fastest over the progressing slope of the dunes ( similar to 2.5 m year super(-1)) and flowering was also stimulated by sand accretion. The time interval between the passage of consecutive dunes, which sets the time window available for patch development, ranged between 2 and 6 years. This time interval allowed C. nodosa to recolonize bare substrata, with patch formation occurring about half a year after the disturbance, and also allowed established shoots to complete their life-cycle and produce seeds and thus enable subsequent recolonization. The time windows available for patch development also set an upper limit to patch size of about 26 m. Significant cross correlations between dune topography and patch dynamics and plant flowering frequency provide evidence that the spatial heterogeneity in the vegetation is closely associated with the disturbance imposed by the migration of sand dunes. The migration of subaqueous dunes maintains C. nodosa in a continuous state of colonization involving spatially asynchronous patch growth and subsequent mortality, which is ultimately responsible for the characteristic patchy landscape of this Bay. 

陕北丘陵沟壑区撂荒地自然恢复植被的组成结构与数量分类

采用样带调查与TWINSPAN分类等方法,对陕北丘陵沟壑区延安、安塞和吴旗174个撂荒地样方的物种组成、出现频率与盖度、及群落类型进行了统计与分类。植被组成结构的统计结果表明:该区自然恢复的植被几乎一半是由禾本科、菊科、豆科和蔷薇科的物种组成,北温带、旧世界温带、世界与泛热带分布成分占到总物种数近75%,且以中旱生、中生和旱生的草本类植物为主,具有典型的温带地面芽植物气候特征。植被的数量分类表明:调查样方基本包括了该区自然恢复的主要植被类型,延安、安塞和吴旗的植被在1年生草本群落到多年生蒿禾类草本群落阶段,依次均以猪毛蒿(Artemisia scoparia)、赖草(Leymussecalinus)、长芒草(Stipa bungeana)、达乌里胡枝子(Lespedeza davurica)、铁杆蒿(Artemisia gmelinii)、茭蒿(Artemisia giraldii)、白羊草(Bothriochloa ischaemun)等为主要优势物种构成的不同组合的植物群落,且这些物种具有较高的盖度和频度;但在植被演替后期,不同植被带及阴阳坡的演替方向却发生了明显的变化。以延安为代表的森林带,阴坡可形成黄...

Spatial patterns and driving forces of land use change in China during the early 21st century

Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km x 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the "Grain for Green" policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of "Western Development", "Revitalization of Northeast", coupled with rapidly economic development during this period.

Uncertainties in estimates of cropland area in China: a comparison between an AVHRR-derived dataset and a Landsat TM-derived dataset

The large uncertainties in estimates of cropland area in China may have significant implications for major cross-cutting themes of global environmental change-food production and trade, water resources, and the carbon and nitrogen cycles. Many earlier studies have indicated significant under-reporting of cropland area in China from official agricultural census statistics datasets. Space-borne remote sensing analyses provide an alternative and independent approach for estimating cropland area in China. In this study, we report estimates of cropland area from the National Land Cover Dataset (NLCD-96) at the 1:100,000 scale, which was generated by a multi-year National Land Cover Project in China through visual interpretation and digitization of Landsat TM images acquired mostly in 1995 and 1996. We compared the NLCD-96 dataset to another land cover dataset at I-km spatial resolution (the IGBP DIScover dataset version 2.0), which was generated from monthly Advanced Very High Resolution Radiometer (AVHRR)-derived Normalized Difference Vegetation Index (NDVI) from April, 1992 to March, 1993. The data comparison highlighted the limitation and uncertainty of cropland area estimates from the DIScover dataset. (C) 2003 Elsevier Science B.V. All rights reserved.

Industrial development and land use/cover change and their effects on local environment: a case study of Changshu in eastern coastal China

The interactions among industrial development, land use/cover change (LUCC), and environmental effects in Changshu in the eastern coastal China were analyzed using high-resolution Landsat TM data in 1990, 1995, 2000, and 2006, socio-economic data and water environmental quality monitoring data from research institutes and governmental departments. Three phases of industrial development in Changshu were examined (i.e., the three periods of 1990 to 1995, 1995 to 2000, and 2000 to 2006). Besides industrial development and rapid urbanization, land use/cover in Changshu had changed drastically from 1990 to 2006. This change was characterized by major replacements of farmland by urban and rural settlements, artificial ponds, forested and constructed land. Industrialization, urbanization, agricultural structure adjustment, and rural housing construction were the major socio-economic driving forces of LUCC in Changshu. In addition, the annual value of ecosystem services in Changshu decreased slightly during 1990-2000, but increased significantly during 2000-2006. Nevertheless, the local environmental quality in Changshu, especially in rural areas, has not yet been improved significantly. Thus, this paper suggests an increased attention to fully realize the role of land supply in adjustment of environment-friendly industrial structure and urban-rural spatial restructuring, and translating the land management and environmental protection policies into an optimized industrial distribution and land-use pattern.

The characteristics of land cover and macroscopical ecology changes in the source region of three rivers in Qinghai-Tibet plateau during last 30 years

We obtained four phases of land cover spatial data sets by interpreting MSS images of middle and late 1970s and three phases of TM images of late 1980s, 2004 and 2008 based on field investigation in Three Rivers' Source Region. We analyzed the temporal and spatial characteristics of land cover and macro ecological changes in Three Rivers' Source Region in Qinghai-Tibet plateau since middle and late 1970s. Indicated by land cover condition index change rate and land cover change index, land cover and macroscopical ecological condition degenerated (7090 period Zc -0.63, LCCI -0.58)-obviously degenerated (9004 period, Zc -0.94, LCCI -1.76)-slightly meliorated (0408 period, Zc 0.06, LCCI 0.33). This course was jointly driven by climate change, grassland stocking pressure and implement of ecological construction project.