Changes In Landscape Dynamics Research Articles

Human-driven global geomorphic change

We synthesize evidence suggesting a chain of global cause-effect relationships, linking population and economic development with cumulative effects on changes in landscape dynamics, including denudation and sediment transport/deposition. Temporal trends in global patterns of geomorphic processes or process combinations such as denudation, sedimentation, or frequency of geomorphic disasters, appear to reflect growing human pressure. Erosion rates, intensified by anthropogenic factors, are currently one to two orders of magnitude greater than prior to the 20th century, and are growing further. Per capita human transfer of Earth materials has increased tenfold. A considerable increase in the frequency of disasters related to geomorphic processes has also taken place in just over half a century, outpacing changes in other natural disasters. It is especially significant that the ratio between the frequency of geomorphic (implying water/land interaction, obviously influenced by climate change) disasters and frequency of purely climate-related disasters has increased more than ten-fold since the early 20th century. The changes described in geomorphic processes (global geomorphic change) appear to respond mainly to land surface modification, which reflects a “Great Geomorphic Acceleration” after the mid-twentieth century. However, these stressors, characteristic of the “Anthropocene”, likely interact with climate change, increasing concerns about future implications for Earth surface dynamics and underscoring the need to not only reduce GHG emissions, but also improve land use practices, which modify the conditions of the terrain.

Typical vegetation dynamics and hydrological changes of Dongting Lake wetland from 1985 to 2020

Dongting Lake wetland provides important ecosystem functions for water regulation and biodiversity protection. However, the construction of the Three Gorges Dam has seriously affected the wetland hydrology and landscape. Therefore, it is of great significance to study the landscape dynamics of Dongting Lake wetland and its response to hydrological changes. Based on GEE cloud platform, this paper will obtain the long-term landscape dynamic changes of Dongting Lake wetland and analyze the influence of changes of multi-period water conditions on wetland landscape. The results show that, 1) From 1985 to 2020, the typical vegetation area of Dongting Lake wetland changed obviously on the whole lake scale. The evolution of wetland landscape pattern mainly occurred in East Dongting Lake, west of South Dongting Lake and north of West Dongting Lake. 2) According to the M-K method, the water level data of Dongting Lake showed a sudden change in 2003. This led to the decline of the annual water level of Dongting Lake and the decline of the water level during the wet season and retreating season. 3) The main hydrological variables affecting the change of the area of C. brevicuspis(Carex brevicuspis) and P. australis(Phragmites australis) in Dongting Lake wetland are the mean water level and minimum water level in wet season, and the mean water level, the minimum water level and the maximum water level in retreating season. This study can be used as a theoretical foundations to protect and restore the wetlands of Dongting Lake and manage the Three Gorges project.

Variação espaço-temporal (1938-2013) do uso e ocupação da terra na região do Saco da Fazenda, Itajaí-SC

O objetivo deste trabalho é a análise da variação temporal da cobertura de uso e ocupação do solo de uma região estuarina no litoral centro-norte do Estado de Santa Catarina, reconstruindo as alterações na dinâmica da paisagem em um período de 75 anos (1938 - 2013), além de calcular as variações do Índice de Uso e Ocupação do Solo (IUO) e do Índice de Cobertura Vegetal (ICV). Para a classificação digital de uso e ocupação do solo foi realizada uma classificação visual, em ambiente SIG. Os resultados indicaram que nas décadas de 30, 50 e 70 ocorreram as maiores transformações na área de estudo, sendo que a variação do IUO apontou um crescimento das áreas antropizadas e o ICV demonstrou uma redução das áreas com vegetação. Estudos desta natureza constituem-se ferramentas importantes para a tomada de decisão dos gestores municipais, na busca de um crescimento mais harmônico das cidades, compatibilizando as necessidades dos moradores por moradias e serviços públicos com os remanescentes naturais, que tem igual importância para a qualidade de vida da população.

Fire as a motor of rapid environmental degradation during the earliest peopling of Malta 7500 years ago

The Holocene colonisation of islands by humans has invariably led to deep-seated changes in landscape dynamics and ecology. In particular, burning was a management tool commonly used by prehistoric societies and it acted as a major driver of environmental change, particularly from the Neolithic onwards. To assess the role of early human impacts (e.g. livestock grazing, forest clearance and the cultivation of marginal land) in shaping “pristine” island landscapes, we here present a 350-year record of fire history and erosion from Malta, straddling the earliest peopling of the island. We show that recurrent anthropogenic burning related to Neolithic agro-pastoral practices began ∼7500 years ago, with well-defined fire-return intervals (FRI) of 15–20 years that engendered erosion and rapid environmental degradation. As early as the Neolithic, this study implies that, in sensitive insular contexts, just a few generations of human activities could rapidly degrade natural islandscapes.

Early Holocene to present landscape dynamics of the tectonic lakes of west-central Mexico

Paleoclimatic reconstructions from lake sediments of central Mexico indicate that the environmental conditions in the Holocene have oscillated from cool-dry to warm-wet, thus, landscape erosion rates have been modified accordingly. The Cenozoic tectonics and volcanic activity of west-central Mexico have produced a set of lakes in warmer and drier conditions compared to lakes of central Mexico. Nevertheless, the Holocene landscape dynamics for this area remains understudied. Using age-depth models, OSL and multi-element chemistry analysis of sediments in the lakes of San Marcos and Sayula we explore the landscape dynamics from early Holocene present of west-central Mexico. Our results indicate that the sedimentation rates in San Marcos Lake notably increased from 240 yr BP to the present. Since AD 1950 the sedimentation rate in Sayula Lake rose fourfold the rates of the last 2000 years. Analysis of OSL and chemistry of major elements of sediments indicates that IRSL/BLSL strongly correlates with Ti/Al (R2 = 0.93) and with the mean monthly rainfall (R2 = 0.70). We propose that the IRSL/BLSL can be used as a proxy to infer past changes in landscape dynamics. Analysis of climatic data from the 1950s to present indicates that rainfall, and consequently water runoff, is enhanced in summers free of ENSO conditions. Extreme one-day rainfall can, however, exceed mean seasonal rainfall and occur in all phases of ENSO. Droughts are particularly severe in the phase of La Niña. Our results indicate that the erosion rate in San Marcos Lake was high from ∼8000 to ∼7000 yr BP in a period coinciding with the advance and recession of glaciers in Central Mexico, however, the erosion rates in the last 165 years have surpassed the rates of the early to mid-Holocene. By constraining the age of sediment and using environmental proxies such as the Ti/Al and IRSL/BLSL from lake sediments of Sayula and San Marcos we present the first model of landscape dynamics of this part of Mexico from the Early Holocene to present times.

Biodiversity conservation in dynamic landscapes: trade‐offs between number, connectivity and turnover of habitat patches

Summary1. Many species are adapted to landscapes with characteristic dynamics generated by ongoing habitat destruction and creation. Climate change and human land use, however, may change the dynamics of these landscapes. Studies have repeatedly shown that many species are not able to cope with such changes in landscape dynamics. Conservation policies must, therefore, explicitly address this threat. The way in which management should be modified when formerly static landscapes become dynamic or when landscape dynamics change is unclear.2. Using an analytical formula for the rapid assessment of metapopulation lifetime in dynamic landscapes, we investigate if and how changes in one landscape attribute may be compensated by changes in another attribute to maintain species viability. We study such trade‐offs considering both spatial (number, connectivity of patches) and temporal (patch destruction and creation rates) landscape attributes.3. We show that increasing patch destruction can be compensated to a certain extent by improvements in other spatial and/or temporal landscape attributes. Focusing on trade‐offs between management options reveals two key factors essential for management decisions: First, the trade‐offs are generally nonlinear irrespective of considering spatial or temporal landscape attributes. Secondly, species can be grouped according to their response to particular management options.4. Synthesis and applications. We demonstrate the usefulness of an analytical formula for calculating trade‐offs between landscape attributes for a variety of landscapes and species. Two practical and robust management recommendations can be derived: (i) The nonlinearity of trade‐offs implies that the effectiveness of conservation measures depends explicitly on the current level of landscape attributes. It must, therefore, be taken into account in conservation decision making. In particular, the existing level of patch turnover is decisive: if it is already high, improvements in other landscape attributes are ineffective in maintaining species viability. Thus, monitoring the current level of landscape attributes is indispensable for effective biodiversity conservation. (ii) Compensation of increased patch destruction by increased patch creation is only suitable for species with high dispersal propensity adapted to variable environments (aside from habitat patch turnover). This implies that conservation policies which rely on such compensation, like offsetting and conservation banking, are feasible only for this type of species.

Analysis on Temporal and Spatial Changes of Landscape Pattern in Dalinor Lake Wetland

Abstract Using TM remote sensing images of Dalinor Natural Reserve in1995, 2000, 2004 and 2008 as a basic information sources, the wetland landscape spatial database for Dalinor Lake was built in this paper. By analyzing spatial variation of different types of wetland landscape and landscape pattern index variation, it revealed the landscape dynamic changes of Dalinor Lake Wetland. The results showed that the grasses grassland landscape is the advantage landscape type in the Dalinor, following by lake water wetland landscape type. From 1995 to 2008, the salt marsh landscape and sandy land landscape increased continuously. While the area of artificial paddy wetland landscape, lake water wetland landscape, swampy meadow landscape and sandy woodland landscape had a reducing trend; Patch density,shannon's diversity index and shannon's evenness index were continue to increase. However, the largest patch index,edge density index,area-weighted fractal dimension and dominance index had a decreasing trend as a whole. It showed that the overall landscape patches developed to small type, the degree of fragmentation and regional landscape heterogeneity increasing.

Mating system, reproduction mode and diaspore size affect metacommunity diversity

1 Metapopulation persistence and metacommunity diversity in patchy dynamic landscapes critically depend on efficient dispersal. Dispersal strategies could involve trade-offs that result in different species responses to habitat fragmentation, alteration in habitat quality and changes in landscape dynamics. 2 We studied spatial structuring in species richness of obligate epiphytic bryophytes in 135 deciduous forest patches in a largely coniferous landscape in Sweden. We tested the effects of forest patch size (0.01–15 ha), patch quality and present and historic connectivity (as revealed by air photographs) on species richness of species groups with different mating systems, reproduction modes and diaspore sizes. 3 Present connectivity to other deciduous forest patches had positive effects on richness of dioecious species with predominant asexual reproduction, whereas richness of monoecious species with predominant sexual reproduction was affected by historic connectivity only. The scale of spatial structuring in species richness increased with decreasing diaspore sizes. Forest patch quality affected richness of monoecious species reproducing sexually but not of dioecious species reproducing asexually. 4 Our results suggest shorter dispersal distances, but higher establishment rates, of large asexual diaspores than of small sexual ones. In monoecious species with sexual reproduction, it may take several decades from establishment to first spore production, and this may explain the strong effect of historic, but not present, forest patch connectivity on species richness of this group. This suggests a trade-off between dispersal distance and age at first reproduction, which may explain the parallel evolution of asexual reproduction and monoecism in species inhabiting patchy, transient habitats. 5 Synthesis. We conclude that dispersal success of metacommunity members is influenced both by species traits and habitat characteristics. In patch-tracking metacommunities, trade-offs in species traits may have evolved as a consequence of conflicting selection pressures imposed by habitat patchiness and dynamics. Syndromes of interrelated species traits imply that fairly small changes in habitat conditions may lead to distinct changes in metacommunity diversity: Species reproducing asexually may drastically decline with increasing distances among patches, whereas sexually reproducing species may decline with increasing patch dynamics.

Detecting Spatiotemporal Dynamic Landscape Patterns Using Remote Sensing and the Lacunarity Index: A Case Study of Haikou City, China

Quantifying the landscape pattern and its dynamics is essential for the monitoring and assessment of the ecological consequences of urbanization. As one of the Special Economic Zones, Haikou is one of the fastest growing regions among all Chinese cities, owing to rapid real estate development. Using a GIS-based land-use dataset from 1986, 1996, and 2000, in combination with a lacunarity index, we attempt to quantify the spatial pattern in the Haikou metropolitan area. After the landscape structure changes over the periods 1986–96 and 1996–2000 are analyzed, a Markov conversion matrix is applied in order to study the sources and destinations of landscape dynamic changes. The lacunarity index is calculated in order to measure the landscape dynamics, with respect to several major land-use types, at a range of spatial scales. The findings indicate that the leapfrog development of real estate and the rapid economic growth of Haikou City have had a great impact on the dynamic landscape patterns. From 1986 to 1996 urban land expanded dramatically and clustered, while cropland was encroached upon and fragmented. From 1996 to 2000, after the government had implemented the strict cropland protection measures, urban expansion and cropland misuse were controlled to a large degree, and a lot of cropland was reclaimed in certain areas. We investigate the dynamic landscape pattern and process, and their implications in policy and economic development.

Alvar Vegetation of Öland—Changes, Monitoring and Restoration

Alvars are habitats characterised by thin soils on limestone bedrock. The largest alvar area in the world is the Stora Alvaret, Oland (25,500 hectares), which is characterised by the presence of several plant communities of high conservation value. Emigration at the end of the nineteenth century reduced land-use intensity resulting in scrub encroachment, mainly by Juniperus communis L. This later accelerated, leading to abandonment because grazing in the low-productivity pastures was uneconomic. Monitoring in permanent plots over a twenty-year period (1971-91) showed an increase in juniper cover over time and a clear correlation with a decline of other vascular plant species. This resulted in a gradual loss of both a valuable mosaic structure and a high level of bio-diversity in the landscape. An EU funded LIFE project (1996-99), which examined the effects of grazing and scrub clearance, is outlined. Various management techniques were tested and evaluated, providing valuable information for the present large-scale restoration and management programme supported by the European Union agri-environment schemes. In 1994 less than 60% of the Stora Alvaret was grazed. By 2005 this had increased to 98%. The reintroduction of grazing has resulted in a significant increase in the abundance of twelve out of 72 vascular species in permanent plots (1997-2001). Sheep and cattle numbers increased in Oland during the last decade, whereas they decreased in Sweden as a whole over the same period. Sixteen nature reserves have been established in Stora Alvaret, and a functioning alvar pasture landscape has been re-established. Almost all alvars in Oland have been designated as Natura 2000 areas. Ejvind Ros?n (e-mail: eje.rosen? ebc.uu.se), Uppsala University, Plant Ecology, Evolutionary Biology Centre, Villav?gen 14, SE-752 36 Uppsala, Sweden. INTRODUCTION This paper gives an overview of the vegetation and land-use history of limestone areas, called alvars, on the island of ?land. The word alvar refers to large areas with various thin deposits of soils, both calcareous and silicious, overlying the bedrock. With a few exceptions these areas are not suitable for cultivation but have been used as pasture for thousands of years. Alvars are mainly located on the Swedish islands of ?land (Rosen 1982; Bengtsson et al. 1988) and Gotland in the Baltic (Ekstam and Forshed 2002), but they also occur in Estonia and western Russia (Partei et al. 1999; Znamenskiy et al. 2006). Similar alvar landscapes occur in the Great Lakes region of Canada and the USA (Catling and Brownell 1995; Stark et al. 2003). *As an abbreviation in the text Stora Alvaret is referred to as Alvar, while alvar is used as a general term. Most attention will be given to the largest area, Stora Alvaret (The Great Alvar)*, covering 25,500ha, located in the southern part of the island. It occupies about half the area of the World Heritage Area known as 'The Agricultural Landscape of Southern Oland'. A total of c. 35,000ha are classified as alvars, however, including smaller areas in the eastern and northern parts of the island (Fig. 1). Alvars on the eastern side are usually part of the more productive grasslands in the coastal zone, while alvars in the north are mostly small and isolated. The latter are mainly located on the western side of the island, which is higher and drier than in the east, but with moist to wet areas occurring in depressions in the bedrock. Interspersed sand and gravel deposits often support small woodlands. Until the 1820s Stora Alvaret was a large commonage. After land reform, nearby villages received their own share of alvar land, which was then usually separated by stone walls. Since then almost all land has been privately owned. Recent land use changes, e.g. overgrazing, abandonment of Biology and Environment: Proceedings of the Royal Irish Academy, Vol. 106B, No. 2, 387-399 (2006). ? Royal Irish Academy 387 This content downloaded from 157.55.39.164 on Thu, 07 Jul 2016 04:43:22 UTC All use subject to http://about.jstor.org/terms Biology and Environment Fig. 1 ? The location of alvars on ?land, with Stora Alvaret in the southern part. Inset shows the location of ?land in the SW part of the Baltic. ?land is part of Kalmar county. grazing, scrub encroachment, etc. have resulted in major changes in landscape dynamics and loss of valuable habitats. The results of different restoration methods and their impact on conservation, as well as monitoring, are presented. BACKGROUND TO THE ECOLOGY OF OLAND

Landscape dynamics and evolution of colonizer syndromes: interactions between reproductive effortand dispersal in a metapopulation

The evolutionary consequences of changes in landscape dynamics for the evolution of life history syndromes are studied using a metapopulation model. We consider in turn the long-term effects of a change in the local disturbance rate, in the maximal local population persistence, in habitat productivity, and in habitat fragmentation. We examine the consequences of selective interactions between dispersal and reproductive effort by comparing the outcome of joint evolution to a situation where the species has lost the potential to evolve either its reproductive effort or its dispersal rate. We relax the classical assumption that any occupied site in the metapopulation reaches its carrying capacity immediately after recolonization. Our main conclusions are the following: (1) genetic diversity modifies the range of landscape parameters for which the metapopulation is viable, but it alters very little the qualitative evolutionary trends observed for each trait within this range. Although they are both part of a competition/colonization axis, reproductive effort and dispersal are not substitutable traits: their evolution reflects more directly the change in the landscape dynamics, than a selective interaction among them. (2) no general syndrome of covariation between reproductive effort and dispersal can be predicted: the pattern of association between the two traits depends on the type of change in landscape dynamics and on the saturation level. We review empirical evidence on colonizer syndromes and suggest lines for further empirical work.