Changes In Land-use Intensity Research Articles

Deep‐sea coral record of human impact on watershed quality in the Mississippi River Basin

AbstractOne of the greatest drivers of historical nutrient and sediment transport into the Gulf of Mexico is the unprecedented scale and intensity of land use change in the Mississippi River Basin. These landscape changes are linked to enhanced fluxes of carbon and nitrogen pollution from the Mississippi River, and persistent eutrophication and hypoxia in the northern Gulf of Mexico. Increased terrestrial runoff is one hypothesis for recent enrichment in bulk nitrogen isotope (δ15N) values, a tracer for nutrient source, observed in a Gulf of Mexico deep‐sea coral record. However, unambiguously linking anthropogenic land use change to whole scale shifts in downstream Gulf of Mexico biogeochemical cycles is difficult. Here we present a novel approach, coupling a new tracer of agro‐industrialization to a multiproxy record of nutrient loading in long‐lived deep‐sea corals collected in the Gulf of Mexico. We found that coral bulk δ15N values are enriched over the last 150–200 years relative to the last millennia, and compound‐specific amino acid δ15N data indicate a strong increase in baseline δ15N of nitrate as the primary cause. Coral rhenium (Re) values are also strongly elevated during this period, suggesting that 34% of Re is of anthropogenic origin, consistent with Re enrichment in major world rivers. However, there are no pre‐anthropogenic measurements of Re to confirm this observation. For the first time, an unprecedented record of natural and anthropogenic Re variability is documented through coral Re records. Taken together, these novel proxies link upstream changes in water quality to impacts on the deep‐sea coral ecosystem.

“交通廊道蔓延”视角下山地城市典型样带空间格局梯度分析

PDF HTML阅读 XML下载 导出引用 引用提醒 “交通廊道蔓延”视角下山地城市典型样带空间格局梯度分析 DOI: 10.5846/stxb201305211130 作者: 作者单位: 重庆工商大学,重庆工商大学,重庆工商大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41101155，41101503，41301351）；教育部人文社科项目（12XJCZH005）；重庆市高等学校青年骨干教师资助计划（2011） Spatial pattern gradient analysis of a transect in a hilly urban area in China from the perspective of transportation corridor sprawl Author: Affiliation: 1. Department of Land Resource Management,Chongqing Technology and Business University,400067,Chongqing,China, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:空间可达性的强弱在一定程度上决定着土地利用变化的方向和强度，因此交通的廊道作用对城市化进程发挥着重要作用。以重庆市轨道交通三号线沿线双侧各3000 m缓冲样带为研究区，采用面向对象分类方法将四期Landsat TM/ETM遥感影像进行土地利用制图，选择核密度估算、指数分析和梯度分析的空间分析方法，研究交通廊道的变化及其对区域空间格局变化的影响。研究表明，研究期内，样带空间的组分和格局发生了较为明显的变化。道路的空间变化和区域空间格局的变化表现出较为明显的梯度性：道路密度、土地利用的变化强度随距离交通主干道距离的远近依次减弱，道路密度等级范围内的土地利用变化强度随等级的降低出现由弱到强再转弱的特征。 Abstract:The improvement of accessibility determines the intensity of land use change. In the past 20 years in China, the development of transportation has accelerated the process of urbanization and land use change. A 6-km distance between two sides of the Chongqing Rail Transit Line 3 was selected as the study area. The research focused mainly on the following key points: (1) how the spatial pattern changed during the study period; (2) how the spatial characteristics of the traffic network changed in the hilly area during the period of rapid development; and (3) how the gradient characteristics of land use changed at different road-density-levels.Chongqing Rail Transit Line 3 was selected as the control line of the study transect. Line 3, the longest single monorail in the world by track length, runs north-south and links districts separated by the two main rivers in Chongqing, the Yangtze (Chángjiāng) and the Jialing (Jiālíngjiāng). Six buffer zones of 500 m (totaling 3 km) were generated along each side of the line.The object-based classification of remote sensing data was applied to map land use. Kernel density estimation (KDE), landscape indices, and gradient analysis were adopted to determine the corridor effect on regional land use. Gradient analysis based on landscape metrics analysis is widely used to study landscape pattern changes in response to rapid urbanization. To discover the relationship of traffic networks and changes in urban patterns of the study area, several landscape metrics were computed along the transect that crosses Chongqing.The results indicate that built-up areas and arable land were the most changed land use types. The urban area expanded from 6550.20 hm2 to 21077.37 hm2. Conversely, the arable land decreased from 27884.07 hm2 to 15929.10 hm2. The changes of road location and land use showed an obvious gradient character, whereby road density and intensity of land use decreased as the distance to Transit Line 3 increased. The transfer of land use changed from weak to strong then to weak.The traffic corridor effect was obvious in Chongqing, a typical hilly city in China. The Chongqing traffic transect in this study clearly illustrates the relationship between regional traffic conditions and urban development. The comparison of buffer zones, road density levels, and land use is an effective way to identify the network character and ecological problems caused by rapid urbanization. This study also effectively quantified the impact of traffic expansion on shaping urban character. 参考文献 相似文献 引证文献

Land-use change in the Atlantic rainforest region: Consequences for the hydrology of small catchments

Summary The Atlantic forest of Brazil is one of the most endangered ecosystems in the world. Despite approximately 500 years of intense land-use change in this biome, the influence of land-use changes on hydrological processes have yet to be investigated in-depth. To bridge this gap, we studied various features of three small catchments covered by pristine original montane cloud forest, pasture, and eucalyptus for 2 years (January 2008–December 2009), including the hydraulic properties of soils, throughfall, overland flow and streamflow processes. The forest saturated hydraulic conductivity (Ksat) was higher near the soil surface (0.15 m depth) compared to eucalyptus and pasture. As a consequence, higher overland flow generation in terms of volume was observed in pasture and eucalyptus. Despite this increase in overland flow generation, overland flow coefficients (overland flow: precipitation ratio) were substantially low throughout the study period with slightly higher values in 2009. These low overland flow coefficients were attributed to the large predominance of low rainfall intensities (

Level of Urbanization and Land Use/Land Cover Landscape Pattern of Relationship Analysis

On the basis of analysis of the development of urbanization and land use change in Zhengzhou City in2004-2010, The drive mechanism of the intensity of land use change in the research context of rapid urbanization, To explore the degree of land use change human driving factors, Drive and build a model, The results show that: Unit of agricultural land and the ratio of the output value of the land for construction as well as population density and land use intensity positive correlation, Making land use intensity tends to increase, The population density growth, Urbanization of the population and economic non-farm is the main driving factor for the intensity of land use change. And then proceed to the analysis of the spatial pattern of Zhengzhou City, Investigate the level of urbanization and land use / cover the relationship between landscape pattern.

Stream Discharge in Tropical Headwater Catchments as a Result of Forest Clearing and Soil Degradation

AbstractTropical Africa is affected by intense land-use change, particularly forest conversion to agricultural land. In this study, the stream discharge of four small headwater catchments located within an area of 6 km2 in western Kenya was examined for 2 years (2007 and 2008). The four catchments cover a degradation gradient ranging from intact forest to agricultural land under maize cultivation for 5, 10, and 50 years. The runoff ratio (e.g., annual catchment discharge expressed as a percentage of rainfall) increased with increasing duration of cultivation from an average of 16.0% in the forest to 32.4% in the 50-yr-old agricultural catchment. Similarly, the average runoff ratio due to the stormflow component was 0.033 in the forest and increased gradually to 0.095 with increasing duration of cultivation. The conversion from forest to agricultural land in the first 5 years caused about half of the total observed increases in runoff ratio (46.3%) and discharge in relation to rainfall (50.6%). The other half of the changes in discharge occurred later during soil degradation after forest clearing. With increasing duration of cultivation, soil bulk density ρb at a depth of 0–0.1 m increased by 46%, while soil organic carbon (SOC) concentrations and total porosity decreased by 75% and 20%, respectively. The changes in hydrological responses that occurred in the initial years after forest clearing may suggest a significant potential for improved land management in alleviating runoff and enhanced storm flow and moisture retention in agricultural watersheds.

Effects of land use intensity on soil nutrient distribution after reclamation in an estuary landscape

The effects of time on the evolution of land use intensity and soil nutrients distribution were studied in a reclamation zone of the Yangtze Estuary. Land use types were grouped into five intensity levels according to the extent of human disturbance. We used the “space for time substitution” method to test the impact of time on changes in land use intensity after reclamation and found that land use levels increased quickly within the first 35 years, then slowed. Soil salinity was relatively higher in aquaculture ponds than that in areas with other types of land cover due to the use of saline water from underground and the sea. Soil organic matter, available phosphorous and nitrate nitrogen were relatively high in agricultural fields, while nitrate nitrogen was highly variable in agricultural fields. The variations of all four soil properties in the built-up zone were much higher than those in the other land use groups. The spatial distribution of different nutrients is the combined effect of time and land use post reclamation. The results will provide a sound basis for future land use planning of newly reclaimed land, and for further studies on ecological consequences of salt marsh reclamation.

The Detection and Analysis of Land Use Change in the Laoha River Basin During the Past Four Decades

On the basis of the multiple remote sensing images of Landsat MSS,TM and ETM+ and other auxiliary data,two classification approaches of decision tree and support vector machine were applied to land use/cover classifications in the semiarid Laoha river basin over the past 40 years since the 1970s.The land use changes and their spatial distribution were analyzed quantitatively and mapped with GIS techniques.The results show that land use/cover maps in 1976,1989,1999 and 2007 could be generated based on the implementation of support vector machine classification with satisfying results.The analysis shows that land use has changed very obviously in the study area over the last 40 years.The areas of water body and grassland have decreased while rural and urban areas increased persistently.The cultivated land area has increased substantially.Forest land and fallow land have changed in fluctuation with a decrease on the whole.It's obvious that the most remarkable change has been the interconversion of lands for agriculture(cultivated land),for forestry(forest land),and for animal husbandry(grassland).Moreover,the spatial distribution of the conversion was greatly different in different periods.An analysis of the intensity of land use changes indicates that the highest annual rate of land use change has been increased gradually and the annual intensity has been spatially heterogeneous.Moreover,the suburbs surrounding Chifeng city always have changed intensively during the past decades,suggesting the persistent urbanization of Chifeng city.

How a socio-ecological metabolism approach can help to advance our understanding of changes in land-use intensity

How a socio-ecological metabolism approach can help to advance our understanding of changes in land-use intensity

Challenges for land system science

While considerable progress has been made in understanding land use change, land system science continues to face a number of grand challenges. This paper discusses these challenges with a focus on empirical land system studies, land system modelling and the analysis of future visions of land system change. Contemporary landscapes are contingent outcomes of past and present patterns, processes and decisions. Thus, empirical analysis of past and present land-use change has an important role in providing insights into the socio-economic and ecological processes that shape land use transitions. This is especially important with respect to gradual versus rapid land system dynamics and in understanding changes in land use intensity. Combining the strengths of empirical analysis with multi-scale modelling will lead to new insights into the processes driving land system change. New modelling methods that combine complex systems thinking at a local level with macro-level economic analysis of the land system would reconcile the multi-scale dynamics currently encapsulated in bottom-up and top-down modelling approaches. Developments in land use futures analysis could focus on integrating explorative scenarios that reflect possible outcomes with normative visions that identify desired outcomes. Such an approach would benefit from the broad and in-depth involvement of stakeholders in order to link scientific findings to political and societal decision-making culminating in a set of key choices and consequences. Land system models have an important role in supporting future land use policy, but model outputs require scientific interpretation rather than being presented as predictions. The future of land system science is strongly dependent on the research community's capacity to bring together the elements of research discussed in the paper, via empirical data collection and analysis of observed processes, computer simulation across scale levels and futures analysis of alternative, normative visions through stakeholder engagement.

Arable land use intensity change in China from 1985 to 2005: evidence from integrated cropping systems and agro economic analysis

SUMMARYA cropping system is the consequence of environmental and socio-economic conditions that determine the intensity of agricultural land use. Accurate information on regional land use intensity and changes in land use intensity is important for food security and sustainable resource management in China. Therefore, a better understanding of the spatial and temporal changes in arable land use intensity (ALUI) based on the cropping system used is essential to comprehend the changes in land use and the sustainability of the food system. The purpose of the present study was to investigate the spatial difference in ALUI and how it has changed in China by comparing data on cropping systems from 1985 and 2005. The basic cropping system data were acquired from the 1985 reference book and the 2005 national land use investigation. The ALUI was defined by the application of inputs (irrigation water and fertilizer) to arable land and the duration of disturbances (the duration of cultivation and the frequency of cropping), and it was calculated using the information entropy approach at the cropping region scale (cropping region being defined by the geographical and climatic conditions at the beginning of the 1980s). Spatial and temporal changes in the ALUI in China over the past two decades were observed and analysed. The results indicated a clear pattern in ALUI, increasing from the north to the south in 2005. Furthermore, the ALUI significantly increased after the 1980s, but the rate of increase was lower in the south than in the north. The most intensive land use in 1985 was in the area of the lower reach of the Yangtze and Huai Rivers, and it expanded northwards towards the Huang-Huai-Hai plain in 2005. The large increase in intensity in the northern single-cropping regions was strongly associated with a rapid increase in inputs and longer duration of cultivation. Decreases in duration of cultivation and planting area helped slow the ALUI increase in multiple cropping regions, which were concentrated in coastal and economically developed regions where more fertile soil and suitable climates existed, allowing the growth of multiple crops. These results suggested that a decrease in the planting area and a slow increase in the ALUI in the lower reaches of the Yangtze River, South China, Southeast China and Northeast China should be of concern, but land use in some western regions should maintain the land production capacity to build sustainable cropping. In the future, it will be necessary to produce more food in a more sustainable way.

Land-use changes and carbon sequestration through the twentieth century in a Mediterranean mountain ecosystem: Implications for land management

Ecosystems in the western Mediterranean basin have undergone intense changes in land use throughout the centuries, resulting in areas with severe alterations. Today, most these areas have become sensitive to human activity, prone to profound changes in land-use configuration and ecosystem services. A consensus exists amongst stakeholders that ecosystem services must be preserved but managerial strategies that help to preserve them while ensuring sustainability are often inadequate. To provide a basis for measuring implications of land-use change on carbon sequestration services, changes in land use and associated carbon sequestration potential throughout the 20th century in a rural area at the foothills of the Sierra Nevada range (SE Spain) were explored. We found that forest systems replaced dryland farming and pastures from the middle of the century onwards as a result of agricultural abandonment and afforestation programs. The area has always acted as a carbon sink with sequestration rates ranging from 28,961 t CO 2 year −1 in 1921 to 60,635 t CO 2 year −1 in 1995, mirroring changes in land use. Conversion from pastures to woodland, for example, accounted for an increase in carbon sequestration above 30,000 t CO 2 year −1 by the end of the century. However, intensive deforestation would imply a decrease of approximately 66% of the bulk CO 2 fixed. In our study area, woodland conservation is essential to maintain the ecosystem services that underlie carbon sequestration. Our essay could inspire policymakers to better achieve goals of increasing carbon sequestration rates and sustainability within protected areas.

The shrinking ark: patterns of large mammal extinctions in India

Mammal extinctions are widespread globally, with South Asian species being most threatened. We examine local extinctions of 25 mammals in India. We use historical records to obtain a set of locations at which each species was known to have been present at some time in the last 200 years. We then use occupancy estimation models to draw inferences about current presence at these same locations based on field observations of local experts. We examine predictions about the influence of key factors such as protected areas, forest cover, elevation, human population density and cultural tolerance on species extinction. For all 25 species, estimated local extinction probabilities (referenced to a 100 year time frame) range between 0.14 and 0.96. Time elapsed since the historical occurrence record was an important determinant of extinction probability for 14 species. Protected areas are positively associated with lower extinction of 18 species, although many species occur outside them. We find evidence that higher proportion of forest cover is associated with lower extinction probabilities for seven species. However, for species that prefer open habitats (which have experienced intensive land-use change), forest cover alone appears insufficient to ensure persistence (the complement of extinction). We find that higher altitude is positively associated with lower extinction for eight species. Human population density is positively associated with extinction of 13 species. We find that 'culturally tolerated' species do exhibit higher persistence. Overall, large-bodied, rare and habitat specialist mammals tend to have higher extinction probabilities.

Recent trends in nutrient concentrations in Estonian rivers as a response to large-scale changes in land-use intensity and life-styles

The aim of the study was assessment of changes in nutrient concentrations in Estonian rivers as a response to improved wastewater treatment and substantial reductions in the use of fertilisers and number of livestock during the past 15-20 years. A Mann-Kendall test and flow adjusted technique to assess recent trends have been used. Statistical analysis covered time series of 53 sampling sites on 40 rivers and streams in different hydro-geographical regions and varying human pressures. The results indicate a statistically significant downward trend in nitrogen concentration in 18 sampling stations during the studied period; only very few showed an upward trend. These decreases in total nitrogen (TN) relate mainly to (i) substantial reductions in the use of fertilisers, (ii) decreased area of agricultural land, (iii) decreased point source load and (iv) increased self-purification capacity of soil-water systems. The concentration of phosphorus decreased only in 13 locations, despite of efforts to improve the efficiency of wastewater treatment. Moreover, in seven locations the concentration of phosphorus was increasing. This increase in total phosphorus (TP) probably relates to the low treatment efficiency of small wastewater treatment facilities as well as to the raised ground water table due to insufficient maintenance of drainage systems that favour transport of soil P to water bodies. Accordingly, the ratio of nitrogen and phosphorus had both decreasing and increasing trends.

Modelling the effects of land-use change on runoff and sediment yield for a meso-scale catchment in the Southern Pyrenees

The Southern Pre-Pyrenees experienced a substantial land-use change over the second half of the 20th century owing to the reduction of agricultural activities towards the formation of a more natural forest landscape. The land-use change over the last 50 years with subsequent effects on water and sediment export was modelled with the process-based, spatially semi-distributed WASA-SED model for the meso-scale Canalda catchment in Catalonia, Spain. It was forwarded that the model yielded plausible results for runoff and sediment yield dynamics without the need of calibration, although the model failed to reproduce the shape of the hydrograph and the total discharge of several individual rainstorm events, hence the simulation capabilities are not yet considered sufficient for decision-making purposes for land management. As there are only a very limited amount of measured data available on sediment budgets with altered land-use and climate change settings, the WASA-SED model was used to obtain qualitative estimates on the effects of past and future change scenarios to derive a baseline for hypothesis building and future discussion on the evolution of sediment budgets in such a dryland setting. Simulating the effects of the past land-use change, the model scenarios resulted in a decrease of up to 75% of the annual sediment yield, whereas modelled runoff remained almost constant over the last 50 years. The relative importance of environmental change was evaluated by comparing the impact on sediment export of land-use change, that are driven by socio-economic factors, with climate change projections for changes in the rainfall regime. The modelling results suggest that a 20% decrease in annual rainfall results in a decrease in runoff and sediment yield, thus an ecosystem stabilisation in regard to sediment export, which can only be achieved by a substantial land-use change equivalent to a complete afforestation. At the same time, a 20% increase in rainfall causes a large export of water and sediment resources out of the catchment, equivalent to an intensive agricultural use of 100% of the catchment area. For wet years, the effects of agricultural intensification are more pronounced, so that in this case the intensive land-use change has a significantly larger impact on sediment generation than climate change. The WASA-SED model proved capable in quantifying the impacts of actual and potential environmental change, but the reliability of the simulation results is still circumscribed by considerable parameterisation and model uncertainties.

Establishing a minimum dataset for soil quality assessment based on soil properties and land-use changes

To assess soil quality, a minimum dataset (MDS) of soil properties has to be proposed commonly through calculating the total load of each candidate soil parameter on all of the qualified principal components by use of principal component analysis (PCA) and Norm-value computation. Considering intensive land-use changes, the method introduced in this study on MDS establishment integrates the quantified contributions of land-use type and land-use duration on each soil parameter by using multivariate analysis and mean multiple comparison. In this way, a MDS maximally representing all candidates with minimal loss of the soil quality information contained by those non-MDS soil parameters is established. The MDS proposed can not only well integrate the quantified influence of land-use changes and land-use duration on soil parameters, but is also quite flexible and extendable with the potential to be extrapolated to assess soil quality in other regions. Based on two sets of soil database obtained separately in 1985 and 2004, two MDSs established are compared with each other. It is found that only quite a small change in MDS components occurs during a 20-year period. For a better assessment of soil quality, it seems necessary to examine on what kind of temporal scale and how much MDS will change for a site-specific area with intensive land-use changes.

Grassland diversity related to the Late Iron Age human population density

1 Species-rich semi-natural grasslands in Europe developed during prehistoric times and have endured due to human activity. At the same time, intensive grassland management or changes in land use may result in species extinction. As a consequence, plant diversity in semi-natural calcareous grasslands may be related to both historical and current human population density. 2 We hypothesize that current vascular plant diversity in semi-natural calcareous grasslands is positively correlated with the Late Iron Age (c. 800-1000 years ago) density of human settlements (indicated by Late Iron Age fortresses and villages) due to enhancement of grassland extent and species dispersal, and negatively correlated with current human population density due to habitat loss and deterioration. 3 We described the size of the community vascular plant species pool, species richness per 1 m(2) and the relative richness (richness divided by the size of the species pool) in 45 thin soil, calcareous (alvar) grasslands in Estonia. In addition to historical and current human population density we considered simultaneously the effects of grassland area, connectivity to other alvar grasslands, elevation above sea level (indicating grassland age), soil pH, soil N, soil P, soil depth, soil depth heterogeneity, geographical east-west gradient, precipitation and spatial autocorrelation. 4 Both the size of the community species pool and the species richness are significantly correlated with the Late Iron Age human population density. In addition, species richness was unimodally related to the current human population density. The relative richness (species 'packing density') was highest in the intermediate current human population densities, indicative of moderate land-use intensity. 5 Community species pool size decreased non-linearly with increasing soil N, and was highest at intermediate elevation. Small-scale richness was greater when sites were well connected and when the elevation was intermediate. Spatial autocorrelation was also significant for both species pool size and small-scale richness. 6 In summary, human land-use legacy from prehistoric times is an important aspect in plant ecology, which could be an important contributor to the current variation in biodiversity. (Less)

Impacts of land-use change on biodiversity: An assessment of agricultural biodiversity in the European Union

The objective of this study is to assess land-use intensity and the related biodiversity in agricultural landscapes of the EU25 for the current situation (2000), and explore future trends, based on the four EURURALIS scenarios up to 2030. Data from the Farm Accountancy Data Network (FADN) were used to classify farm types in 100 regions of the EU15, according to agricultural intensity. For the ten New Member States (EU10), which are not yet considered by the FADN, country level data were used to obtain similar farm types. Three processes were considered for the assessment of future trends in agricultural land-use intensity: (1) land-use change, (2) conversion into organic farming, and (3) changes in productivity of crop and grassland production. An ecosystem quality value was attributed to each farm type according to dose-effect relationships between pressure factors and biodiversity compared to the value for an undisturbed situation. The biodiversity in agricultural landscapes was then calculated as the average ecosystem quality multiplied by the relative area size of each farm type within a region. A similar method of attributing ecosystem quality values to other land-use types allowed comparison between different land-use types. Referring to the current situation, results indicate the lowest ecosystem quality values to be found in intensively used agricultural areas in lowlands (e.g. The Netherlands and northern France) and irrigation systems (e.g. Greece), whereas relatively high values are found in Spain and the New EU Member States. Scenario results show that for the A1 scenario (Global economy), the highest loss in ecosystem quality will take place in all regions in croplands and grasslands. The B2 scenario (Regional communities) provides the best opportunities to improve ecosystem quality of agricultural landscapes. In most scenarios, agricultural land is decreasing, while the remaining agricultural areas tend to be used more intensively. The negative impact of intensification on biodiversity is partly set off by (active or spontaneous) nature development on abandoned agricultural areas, but the overall trend seems to be generally negative. The strength of this methodology is that it provides a quick overview of land-use intensity change and biodiversity trends. Through the use of this farm-type level of analysis we have provided a good picture of the differences in land-use intensity and the related biodiversity between the EU regions and the scenarios.

Changes in landscape spatial pattern in the highly developing state of Selangor, peninsular Malaysia

In Malaysia, rapid changes in land use invariably portrayed have a relationship with environmental degradation. However, this has always been stated without any quantitative measurement for understanding the relationship in order to describe implications for land use planning and management. To understand the relationship this study addresses landscape pattern and landscape type responses to changes in land use in the state of Selangor, Malaysia as a case study. Three land use maps representing the years of 1966, 1981 and 1995 were used in this study. These maps were divided into 100 grid squares with each grid square has 10 km × 10 km dimension. These grid squares were used as a sampling unit for land use and landscape pattern change analyses. Based on proportion of land use categories, the landscape type of each grid square was determined. Results show that between 1966 and 1981 only one land use category significantly changed ( p < 0.05) in its proportion compared to five land use categories between 1981 and 1995. This indicates that human land use intensity increased between 1981 and 1995. As response to the intensity of land use change, fragmentation (measured by number of patches and mean patch size metrics) and diversity (measured by relative patch richness metric) of the state's landscape increased from 1981 to 1995. Changes in land use also influenced the landscape types and its dynamic of change. Two categories of landscape types; human landscape (cropland, semi-natural and mixed landscapes) and natural landscape (forest and wetland landscapes) characterized the state landscape. Based on the number of grid squares human landscape increased over the period, whereas natural landscape decreased. Between 1966 and 1981, change from one landscape type to another was predominantly occurred in human landscape. Between 1981 and 1995, change was mainly occurred in the natural landscape. Developmental activities might have been less intense in the human landscape, but they had a much greater impact on the natural ecosystem. This study also revealed the potential of landscape type as a reference for land evaluation and complement to landscape metric as measurement for monitoring changes in a landscape. Finally, we conclude that it is important to understand the changes of land use intensification and its effects on landscape pattern as well as landscape types and their dynamic of change in order to describe the implications for land use planning and management.

Response of small New England ponds to historic land use

This palaeolimnological study addresses whether the timing, magnitude and nature of lake-ecosystem changes closely track changes in land-use intensity and forest cover in the watershed, and the extent to which lakes retuni to pre-disturbance states following the substantial long-term declinie in human activity that is typical for much of the rural eastern United States. Land-use intensity in the watersheds increased rapidly witlh European settleminent and forest clearance, peaked in the mid-nineteenth century when 60-80% of the land was cleared for agriculture, and then declined to the present as natural reforestation resulted in 65-90% forest cover. Land-use intensity in the three watersheds studied ranged from limited logging to extensive clearance for pasturing and to total clearance for pasture and tillage. In contrast to many studies in which human activity continues to increase throughout the settlement period, all three watersheds now support mature, growing forest and are in their most natural condition in the last 200 years. Dated cores from three ponds were analysed for pollen, fossil chironomids, percenit organic matter and sedimentation changes to compare lake and vegetation change among sites. Increased sedimenit-accumulation rates and small increases in productivity occurred in all lakes during the settlement period. Both tremain higher thani pre-settlement levels, indicating that despite lengthy periods without disturbance and a return to completely forested conditions, the systems and sediment records have not returned to pre-disturbance states. In contrast with results from many other palaeolimnological studies, the magnitude of lake response was slight, probably due to the low intensity of nineteenth-century agriculture and the small watershed sizes.

Are agricultural land-use models able to predict changes in land-use intensity?

Land-use and land-cover change research needs to pay more attention to processes of land-cover modification, and especially to agricultural land intensification. The objective of this paper is to review the different modelling approaches that have been used in land-use/land-cover change research from the perspective of their utility for the study and prediction of changes in land-use intensification. After clarifying the main concepts used, the different modelling approaches that have been used to study land-use change are examined, case study evidence on processes and drivers of land-use intensification are discussed, and a conclusion is provided on the present ability to predict changes in land-use intensity. The analysis suggests there are differences in the capability of different modelling approaches to assess changing levels of intensification: dynamic, process-based simulation models appear to be better suited to predict changes in land-use intensity than empirical, stochastic or static optimisation models. However, some stochastic and optimisation methods may be useful in describing the decision-making processes that drive land management. Case study evidence highlight the uncertainties and surprises inherent in the processes of land-use intensification. This can both inform model development and reveal a wider range of possible futures than is evident from modelling alone. Case studies also highlight the importance of decision-making by land managers when facing a range of response options. Thus, the ability to model decision-making processes is probably more important in land-use intensification studies then the broad category of model used. For this reason, landscape change models operating at an aggregated level have not been used to predict intensification. In the future, an integrated approach to modelling — that is multidisciplinary and cross-sectoral combining elements of different modelling techniques — will probably best serve the objective of improving understanding of land-use change processes including intensification. This is because intensification is a function of the management of physical resources, within the context of the prevailing social and economic drivers. Some of the factors that should be considered when developing future land-use change models are: the geographic and socio-economic context of a particular study, the spatial scale and its influence on the modelling approach, temporal issues such as dynamic versus equilibrium models, thresholds and surprises associated with rapid changes, and system feedbacks. In industrialised regions, predicting land-use intensification requires a better handling of the links between the agriculture and forestry sectors to the energy sector, of technological innovation, and of the impact of agri-environment policies. For developing countries, better representation of urbanisation and its various impacts on land-use changes at rural-urban interfaces, of transport infrastructure and market change will be required. Given the impossibility of specific predictions of these driving forces, most of the modelling work will be aimed at scenario analysis.