Landscape structure and the disturbance regime at three rural regions in Hiroshima Prefecture,Japan

Using the vegetation maps of island, inland and mountainous rural regions in Hiroshima Prefecture in western Japan, landscape structures in terms of the size and number of patches are compared, and the characteristics of the disturbance regimes creating each landscape are discussed. Landscape structure in the island rural region is the most heterogeneous, because factors which alter the landscape structure are the most complex. This heterogeneity is established and kept by the agricultural land uses and natural disturbances such as forest fire and pine-disease. At the mountainous rural region, the landscape mosaic is characterized by the relatively large patches composed of conifer plantations and secondary deciduous oak forests. This is the result of the forestry. The inland region landscape is the most homogeneous, because factors which alter landscape structure are now absent. The complex of the physical, biological and anthropogenic forces makes the landscape unique to each region.     

Effects of fire frequency on plant communities and landscape pattern in the Massif des Aspres (southern France)

Fire frequency can affect pattern and diversity in plant communities and landscapes. We had the opportunity to study changes due to recurring wildfires on the same sites over a period of 50 years in the Massif des Aspres (southern France). The study was carried out in areas occupied byQuercus suber andQ. ilex series. A comparison of historical and cartographical documents (vegetation maps covering a 50 year interval and an accurate map of major wildfires during this period) allowed us to determine the changes occurring over time with or without fire action. Plant communities were grouped into three main vegetation types: forests, treed shrublands and shrublands. The passage of three successive wildfires on the same site led to a decrease in forest areas and an increase in shrublands; however, shrublands were already present before the first fire of the period under consideration. Less frequent fire occurrence induced more complex heterogeneity and greater landscape diversity. In the study region as a whole, with or without fire action, a significant decrease in forest surfaces was recorded, whereas there was an increase of unforested communities such as treed shrublands and shrublands. In some parts of the Massif fires increased the homogeneity of the landscape, in other parts they created a greater heterogeneity and diversity of plant communities.     

Evolving core-periphery interactions in a rapidly expanding urban landscape: The case of Beijing

We characterized and analyzed the dynamics of a rapidly expanding urban landscape of Beijing Municipality, based on the Hierarchical Regional Space (HRS) model. We focused on ecological processes such as flows of energy, materials and population between the urban core and its periphery, and how these processes co-evolved with urbanization. We treated the HRS as an alternative to the cellular automata (CA) approach to characterizing and modeling of landscape dynamics. With LANDSAT data, we showed that the urban area of Beijing expanded from 269 km² to 901 km² in the period from 1975 to 1997, an increase of 2.35 times in 22 years. Meanwhile, a number of secondary urban centers formed on areas that used to be sparsely populated around the city. These secondary centers quickly expanded and ultimately merged with each other and with the urban core. The changes in spatial pattern and organization were accompanied by evolution of urban functions and particularly the interactions between the urban core and its periphery. We demonstrated a dramatic increase in dependence of the urban core on the periphery as well as the cores influence on the periphery with a case analysis of the vegetable supply to Beijing. The tightening link between the city and its periphery reinforces the urbanization process and further drives the transformation of the regions landscape. We conclude that the HRS model is capable of characterizing the patterns and processes of complex and dynamic landscapes such as the case of Beijing, and this model has great potential for quantitative modeling of human dominated landscapes as well.This revised version was published online in May 2005 with corrections to the Cover Date.     

Consequences of less intensive farming on the landscape: an example of vegetation dominance by Chaerophyllum aureum in the meadows of a Pyrenean valley in France

The impact of agricultural practices on the dynamics of weed invasion in a rural landscape was studied by describing the spatial distribution of Chaerophyllum aureum populations colonising less intensive managed hay meadows. Polyphenol compounds were used as individual markers to identify the structure of C. aureum diversity, in terms of its scale and patterns, within and between fields along the bottom of a Pyrenean valley. The results revealed, firstly, the existence of a dominant `genotype' successfully colonising the entire area, and secondly, the maintenance of high levels of polyphenol diversity within five different populations. This spatial arrangement of `genetic' population diversity was obviously not related to the natural reproduction and dispersal patterns of this species, but to human practices of hay production, the principal effect of which is to mix seeds of different genetic origin and thus accelerate and amplify the colonisation process of adapted `genotypes'.     

Modelling the effects of landscape pattern and grazing regimes on the persistence of plant species with high conservation value in grasslands in south-eastern Sweden

Semi-natural grasslands in Sweden are threatened by land-use change and lack of management with attendant risk to their biodiversity. We present a model to explore the effects of grazing frequency and intensity on plant species persistence, and the relative effects of grassland size and pattern. We used a landscape modelling platform, LAMOS (LAndscape MOdelling Shell), to design a landscape model of vegetation dynamics incorporating the effects of local succession, dispersal and grazing disturbance. Five plant functional groups (PFG), representing various combinations of persistence and dispersal character, light requirements and disturbance responses, were defined to model species dynamics. Based on old cadastral maps three different landscapes were designed representing specific time-layers, i.e., a historical (17th to 18th century), a pre-modern (1940s) and a present-day landscape. Simulations showed that a threshold was crossed when grasslands decreased in area to about 10–30% of the modelled area, and as a consequence the biomass of grassland-specific PFGs was strongly reduced. These competition sensitive groups did not persist in the model even with intense grazing in the present-day landscape, where grasslands occupy 11% of the total area. However, all grassland species would have been able to persist in the historical landscape, where grasslands occupied 59% of the total area, even without grazing. Our results suggest that continuous but low-intensity grazing is more positive for grassland PFGs than discontinuous but highly intensive grazing. This effect was particularly strong when the frequency and/or intensity of grazing dropped below a threshold of 20%. Simulations using three landscape maps designed to explore effects of further fragmentation and habitat loss showed that the spatial pattern of remaining grasslands is important for the persistence of grassland-specific PFG. The model presented here is an advance towards more realistic grazing models to explore the effects of prescribed grazing and landscape fragmentation on the persistence species or plant functional groups.This revised version was published online in May 2005 with corrections to the Cover Date.     

Ownership and ecosystem as sources of spatial heterogeneity in a forested landscape,Wisconsin, USA

The interaction between physical environment and land ownership in creating spatial heterogeneity was studied in largely forested landscapes of northern Wisconsin, USA. A stratified random approach was used in which 2500-ha plots representing two ownerships (National Forest and private non-industrial) were located within two regional ecosystems (extremely well-drained outwash sands and moderately well-drained moraines). Sixteen plots were established, four within each combination of ownership and ecosystem, and the land cover on the plots was classified from aerial photographs using a modified form of the Anderson (U.S. Geological Survey) land use and land cover classification system.Upland deciduous forests dominated by northern hardwoods were common on the moraines for both ownerships. On the outwash, the National Forest was dominated by pine plantations, upland deciduous forests, and upland regenerating forests (as defined by <50% canopy coverage). In contrast, a more even distribution among the classes of upland forest existed on private land/outwash. A strong interaction between ecosystem and ownership was evident for most comparisons of landscape structure. On the moraine, the National Forest ownership had a finer grain pattern with more complex patch shapes compared to private land. On the outwash, in contrast, the National Forest had a coarser grain pattern with less complex patch shapes compared to private land. When patch size and shape were compared between ecosystems within an ownership, statistically significant differences in landscape structure existed on public land but not on private land. On public land, different management practices on the moraine and outwash, primarily related to timber harvesting and road building, created very different landscape patterns. Landscape structure on different ecosystems on private land tended to be similar because ownership was fragmented in both ecosystems and because ownership boundaries often corresponded to patch boundaries on private land. A complex relationship exits between ownership, and related differences in land use, and the physical environment that ultimately constrains land use. Studies that do not consider these interactions may misinterpret the importance of either variable in explaining variation in landscape patterns.     

The change of a satoyama landscape and its causality in Kamiseya,Kyoto Prefecture,Japan between 1970 and 1995

We focused on patterns of land use in a particular satoyama landscape (Japanese traditional rural landscape, comprised of an integral social and ecological network of a village and its surroundings, such as agricultural lands, open forestlands and forests), and the effects of human activities upon them during Japan’s economic growth of the last few decades. Changes of landscape patterns and their probable causes were traced since the beginning of the 1900s to the present, and clarified. Societal, economic and technological changes, especially those that occurred after 1970, were considered the focal points from which major landscape changes developed. We compared the spatial features, patterns of land use and landscape diversities of each land unit, defined in terms of both their natural and man-made conditions for the year 1970, to those of 1995. We found land-use diversity to be strongly related to changes in the patterns of land use, with a decrease in diversity for all land units after 1970. Diversity of forest-age distribution on the other hand, increased. These changes, with the complex, changing patterns of each land unit, could be explained by differences in accessibility from the village and variations in the topography, as well as land ownership of the land units. We selected those land units found to have responded to these factors between 1970 and 1995, and classified them into four types of pattern changes, determined mainly by accessibility and topography.This revised version was published online in May 2005 with corrections to the Cover Date.     

Cooling and humidifying effect of plant communities in subtropical urban parks

Urban vegetation has been proved to play an important role in mitigating the heat island effect. However, it is not clear how independent small-scale plant communities affected the microclimate. In this paper, the effects of fifteen plant communities on temperature and relative humidity were investigated from November 2010 to October 2011 in urban parks in subtropical Shenzhen City, China. The canopy density, canopy area, tree height and the background climate conditions under plant communities were measured. The effects of small-scale plant communities on temperature and relative humidity were the most significant at 1400–1500 h during the day. The temperature reduction and relative humidity increase due to small-scale plant communities were higher in summer, followed by autumn, spring and winter. As compared to the control open sites, the temperature reduction due to plant communities ranged from 2.14 °C to 5.15 °C, and the relative humidity increase ranged from 6.21% to 8.30%. We found that multilayer plant communities were the most effective in terms of their cooling and humidifying effect, while bamboo groves were the least effective. Regression results revealed that four factors, namely canopy density, canopy area, tree height and solar radiation, had significant influence on temperature reduction and relative humidity increase.     

Spatial patterns of sand pine invasion into longleaf pine forests in the Florida Panhandle

Land use practices since European settlement have had profound effects on the composition and structure of certain forested ecosystems in the southeastern U.S. Coastal Plain. One significant change since the turn of the century has been the invasion of upland pine forests by sand pine in the state of Florida panhandle and peninsula. This study quantified sand pine extent and expansion and examined links between sand pine distribution and environmental factors in the Florida panhandle. Geographic information system analysis using aerial photographs (1949 and 1994) showed sand pine expansion and also increased canopy cover of sand pine over time. There was a high rate of conversion of longleaf pine to sand pine from 1949 to 1994 (44%), and conversion of sparse sand pine stands to dense sand pine stands (69%). Therefore, widespread changes in the Florida landscape were evident during a relatively short time period. Adjacency analyses showed a strong negative association between longleaf pine and dense sand pine and a positive association between riparian vegetation and dense sand pine. Distribution of sand pine across elevation demonstrated that sand pine expanded inland and upland into longleaf-pine forests. In 1949, sand pine was selectively located on sites below 30 m in elevations; by 1994, sparse and moderately dense sand-pine stands were found at all elevations. Thus, any area that may receive an input of sand pine seeds, most notably from riparian areas, is vulnerable to establishment.     

Metapopulation genetic structure and migration pathways in the land snail Helix aspersa: influence of landscape heterogeneity

The spatial genetic structuring of the land snail Helix aspersa was investigated for 32 colonies within an intensive agricultural area, the polders of the Bay of Mont-Saint-Michel (France). Given the habitat patchiness and environmental instability, the setting of H. aspersa colonies meets the broader view of a metapopulation structure. The identification of extrinsic barriers to migration and their impact on the genetic distribution was addressed through the genotyping of 580 individuals using a combined set of enzyme and microsatellite loci. To evaluate the distance as well as the direction over which the spatial genetic arrangement occurs, two-dimensional spatial autocorrelation analyses, Mantel tests of association and multivariate Mantel correlograms were used. Different connectivity networks and geographical distances based on landscape features were constructed to evaluate the effect of environmental heterogeneity and to test the adequacy of an isolation by distance model on the distribution of the genetic variability. Genetic divergence was assessed using either classical IAM-based statistics, or SMM-based genetic distances specifically designed to accommodate the mutational processes thought to fit microsatellite evolution (IAM: Infinite Allele Model; SMM: Stepwise Mutation Model). Genetic distances based only on genetic drift yielded the most plausible biologically meaningful interpretation of the observed spatial structure. Applying a landscape-based geographical distance which postulates that migration arises along roadside verges, hedges or irrigation canal embankments gave a better fit to an isolation by distance model than did a simple Euclidean distance. The progressive decline of genetic similarity with physical distance appeared to be environmentally induced, leading to functional migration pathways.This revised version was published online in May 2005 with corrections to the Cover Date.     

Temporal and spatial changes in an area of the New Jersey Pine Barrens landscape

In order to document the extent of landscape fragmentation for a section of the New Jersey Pine Barrens region, we have used satellite image and spatial analysis to monitor landscape change between 1972 and 1988. Land-cover patterns were quantified by mean, number, and size of patches; and amount of edges between land cover types. During the intervening sixteen year period, fractal dimension, diversity, and contagion generally decreased while dominance, disturbance and edges increased, indicating a trend to a more dissected and disturbed landscape. There was an increase in the number of forest patches and a significant decrease in the average size of forest patches. In contrast, the mean patch size for the non-forest category has increased as a result of a coalescence of patches. The landscape fragmentation is shown by a downward shift in the distribution of forest patches by size class. These changes in landscape pattern have implications for many ecological processes and resources. Management practices need to consider landscape fragmentation in the Pinelands National Reserve in order to preserve the essential character of the Pine Barrens landscape.     

Land-use changes in Illinois,ASA: The influence of landscape attributes on current and historic land use

The Illinois Geographic Information System was used to compare the soil and landscape attributes of the State with its historic vegetation, current land use, and patterns of land-use change over the past 160 years. Patch structural characteristics among land types in four geographic zones were also compared. The assessment of patch characteristics revealed a highly modified State with most land patches controlled by human influences and relatively few by topographic and hydrologic features. Correlation and regression analyses determined the relationships of land type and abundance within each of 50 general soil associations to properties of the soil associations - typically slope, texture, organic matter, productivity index, and available waterholding capacity. The distribution of the historic vegetation of the State and its current deciduous forests and nonforested wetlands related moderately (r² 0.44) to various landscape attributes. Urban and other highly modified land types were less closely related.     

Evaluating the effects of changes in landscape structure on soil erosion by water and tillage

Landscape structure, or the spatial organization of different land units, has an impact on erosion and sedimentation on agricultural land. However, current erosion models emphasize the temporal, and less the spatial, variability of relevant parameters so that the effects of changes in landscape structure have hitherto not been studied in detail. Therefore, a spatially distributed water and tillage erosion model that allows the incorporation of landscape structure is presented. The model is applied to three study sites in the Belgian Loam Belt where significant changes in landscape structure occurred over the last fifty years. Erosion rates were shown to change by up to 28% however, with decreases as well as increases occurring. These could be explained by the interaction of changes in land use with changes in the position of field boundaries. Thus, landscape structure is an important control when the effect of environmental change on erosion risk is to be assessed.     

Rates and patterns of landscape change in the Central Sikhote-alin Mountains,Russian Far East

We used Landsat imagery and GIS to quantify the rates and patterns of landscape change between 1972 and 1992 for a 734,126 ha forested study area in the central Sikhote-alin Mountains of the Russian Far East. The study area includes a portion of the Sikhote-alinskiy Biosphere Reserve which is a part of the United Nations international Man and the Biosphere (MAB) reserve network. Wildfire is a major disturbance agent throughout the area and timber harvesting outside the reserve is also important. Maximum likelihood classification of the satellite imagery identified four broad cover types (hardwood, conifer, mixed and non-forest) in 1992 and changes among them between 1972 and 1992. We used multi-temporal principal components analysis to describe the magnitude and direction of landscape change for six watersheds that represent a range of ecological histories and disturbance regimes. Overall, forest cover declined from 90.4% in 1972 to 77.2% in 1992. The disturbance rate was more than twice as high in conifer than in hardwood forests. The rate of disturbance outside the reserve was three times that inside. While the rates of disturbance are not markedly higher than those recorded from other temperate forests, there has recently been a large alteration in the disturbance regime which will lead to a general transformation of forest composition and structure in the study area if the trend continues.     

Cumulative effects of roads and logging on landscape structure in the San Juan Mountains,Colorado (USA)

In the southern Rocky Mountains of temperate North America, the effects of Euro-American activities on disturbance regimes and landscape patterns have been less ubiquitous and less straightforward in high-elevation landscapes than in low-elevation landscapes. Despite apparently little change in the natural disturbance regime, there is increasing concern that forest management activities related mainly to timber harvest and to the extensive network of roads constructed to support timber harvest, fire control, and recreation since the late 1800s have altered disturbance regimes and landscape structure. We investigated the magnitude of change in landscape structure resulting from roads and logging since the onset of timber harvest activities in 1950. We found limited evidence for significant impacts in our study area when all lands within the landscape were considered. The relatively minor changes we observed reflected the vast buffering capacity of the large proportion of lands managed for purposes other than timber (e.g., wilderness). Significant changes in landscape structure and fragmentation of mature forest were, however, evident on lands designated as suitable timberlands. Roughly half of the mature coniferous forest was converted to young stands; mean patch size and core area declined by 40% and 25%, respectively, and contrast-weighted edge density increased 2- to 3-fold. Overall, roads had a greater impact on landscape structure than logging in our study area. Indeed, the 3-fold increase in road density between 1950–1993 accounted for most of the changes in landscape configuration associated with mean patch size, edge density, and core area. The extent of area evaluated and the period over which change was evaluated had a large impact on the magnitude of change detected and our conclusions regarding the ecological significance of those changes. Specifically, the cumulative impact on landscape structure was negligible over a 10-year period, but was notable over a 40-year period. In addition, the magnitude of change in landscape structure between 1950–1993 varied as a function of landscape extent. At the scale of the 228000 ha landscape, change in landscape structure was trivial, suggesting that the landscape was capable of fully incorporating the disturbances with minimal impact. However, at intermediate scales of 1000–10000 ha landscapes, change in landscape structure was quite evident, suggesting that there may be an optimal range of scales for detecting changes in landscape structure within the study area.     

Spatial pattern of coniferous and deciduous forest patches in an Eastern North America agricultural landscape: the influence of land use and physical attributes

In agricultural landscapes, most studies have investigated the influence of the spatial pattern of forest patches on other ecological phenomena and processes, such as animal movement and biodiversity. However, few have focused on explaining the spatial pattern of the forest patches themselves. Understanding how these patterns relate to the processes that generate them is fundamental in developing a sound theory of landscape ecology, and in devising rational management strategies. In this paper, the pattern of the overall forest patches, as well as the pattern of deciduous and coniferous patches in an agricultural landscape of Southern Quebec, Canada, were analyzed and related to landscape physical attributes and land use, using remote sensing, geographic information systems and statistical methods. Results show that the role of landscape physical attributes on forest patch pattern has been modified by land use. In the study area, coniferous or deciduous patches are not associated with a specific surface deposit. In addition, physical attributes explain only a small proportion of the abundance of conifers on past abandoned land compared with land-use factors. Physical attributes only indirectly influence the forest pattern because they strongly influence the land-use practices. Our results reveal a conifer recovery process with the abandonment of agricultural land. On past abandoned land, conifers expand with increasing stand age, mostly by invasion from neighboring coniferous patches. Spatially, coniferous patches are usually located on the margins of the overall forest patches, and they are connected to non-forest land-use types such as crop and pasture, the latter being the most important. By showing the importance of some coniferous forest types that did not exist in the precolonial forest, a new perspective emerges when landscape, especially, land-use dynamics are taken into account.     

Rates and patterns of landscape change between 1972 and 1988 in the Changbai Mountain area of China and North Korea

Satellite imagery was used to quantify rates and patterns oflandscape change between 1972 and 1988 in the Changbai MountainReserve and its adjacent areas in the Peoples Republic of Chinaand North Korea. The 190,000 ha Reserve was established as anInternational Biosphere Reserve by The United Nations Educational,Scientific and Cultural Organization (UNESCO) in 1979. It is themost important natural landscape remaining in Chinastemperate/boreal climate. The images used in this research cover atotal area of 967,847 ha, about three-fourths of which is in China.Imagery from 1972 and 1988 was classified into 2 broad cover types(forest and non-forest). Overall, forests covered 84.4% of thestudy area in 1972 and 74.5% in 1988. Changes in forest coverwithin the Reserve were minimal. The loss of forest cover outsidethe Reserve appears to be strongly associated with timberharvesting at lower elevations. Landscape patterns in 1988 weremore complex, more irregular, and more fragmented than in 1972.This is one of the few studies to assess landscape changes acrosstwo countries. The rates and patterns of forest-cover loss weredifferent in China and North Korea. In North Korea, extensivecutting appears to have occurred prior to 1972 and this hascontinued through 1988 while in China, most cutting appears to haveoccurred since 1972.     

Historic landscape change and habitat loss: the case of black grouse in Lower Saxony,Germany

The declines of many specialist bird species in the agricultural landscapes of Central Europe have resulted in small and isolated populations. In the case of the black grouse, a ground-nesting bird species with large spatial requirements, empiric evidence about underlying landscape changes is scarce. In this study, we examined land cover and land cover changes in a farmland-forest mosaic in eastern Lower Saxony, Germany and how they affect occurrence and persistence of black grouse. Spatial information came from historic topographic maps from 1958 to 1975. The results show profound conversions of habitat to forest and farmland but also an increase in settlement area. Habitat conversions and suburbanization were negative correlates of black grouse persistence. Habitat models from before and after a decline period differed in some of the predictors and suggest black grouse habitat to be more diverse before the land cover changes. Our study confirms that land use factors at a landscape scale extent contribute to explain black grouse occurrence and thus can complement important small scale factors like the quality and size of individual habitat patches. Results also show that landscape factors affect black grouse distribution predominantly from an area much greater than an individual black grouse home range. Our models may be further evaluated on present-day landscapes and might be used to evaluate large-scale habitat availability for black grouse.