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Vegetation Map (vegetation + map)

Distribution by Scientific Domains

Earth and Environmental Science	66%
Life Sciences	27%

Selected Abstracts

Modeling landscape patterns of understory tree regeneration in the Pacific Northwest, USA

APPLIED VEGETATION SCIENCE, Issue 2 2001
Michael C. Wimberly
Abstract. Vegetation maps serve as the basis for spatial analysis of forest ecosystems and provide initial information for simulations of forest landscape change. Because of the limitations of current remote sensing technology, it is not possible to directly measure forest understory attributes across large spatial extents. Instead we used a predictive vegetation mapping approach to model Tsuga heterophylla and Picea sitchensis seedling patterns in a 3900-ha landscape in the Oregon Coast Range, USA, as a function of Landsat TM imagery, aerial photographs, digital elevation models, and stream maps. Because the models explained only moderate amounts of variability (R2 values of 0.24,0.56), we interpreted the predicted patterns as qualitative spatial trends rather than precise maps. P. sitchensis seedling patterns were tightly linked to the riparian network, with highest densities in coastal riparian areas. T. heterophylla seedlings exhibited complex patterns related to topography and overstory forest cover, and were also spatially clustered around patches of old-growth forest. We hypothesize that the old growth served as refugia for this fire-sensitive species following wildfires in the late 19th and early 20th centuries. Low levels of T. heterophylla regeneration in hardwood-dominated forests suggest that these patches may succeed to shrublands rather than to conifer forest. Predictive models of seedling patterns could be developed for other landscapes where georeferenced inventory plots, remote sensing data, digital elevation models, and climate maps are available. [source]

Tracking Fragmentation of Natural Communities and Changes in Land Cover: Applications of Landsat Data for Conservation in an Urban Landscape (Chicago Wilderness)

CONSERVATION BIOLOGY, Issue 4 2001
Yeqiao Wang
Within the metropolis survive some of the world's best remaining examples of eastern tallgrass prairie, oak savanna, open oak woodland, and prairie wetland. Chicago Wilderness is more than 81,000 ha of protected areas in the urban and suburban matrix. It also is the name of the coalition of more than 110 organizations committed to the survival of these natural lands. The long-term health of these imperiled communities depends on proper management of the more extensive, restorable lands that surround and connect the patches of high-quality habitat. Information critical to the success of conservation efforts in the region includes (1) a current vegetation map of Chicago Wilderness in sufficient detail to allow quantitative goal setting for the region's biodiversity recovery plan; (2) quantified fragmentation status of the natural communities; and (3) patterns of land-cover change and their effects on the vitality of communities under threat. We used multispectral data from the Landsat thematic mapper (October 1997) and associated ground truthing to produce a current vegetation map. With multitemporal remote-sensing data (acquired in 1972, 1985, and 1997), we derived land-cover maps of the region at roughly equivalent intervals over the past 25 years. Analyses with geographic information system models reveal rapid acceleration of urban and suburban sprawl over the past 12 years. Satellite images provide striking visual comparisons of land use and health. They also provide banks of geographically referenced data that make quantitative tracking of trends possible. The data on habitat degradation and fragmentation are the biological foundation of quantitative goals for regional restoration. Resumen: En Chicago hay una concentración de comunidades naturales globalmente significativas sorprendentemente alta. En la metrópolis sobreviven algunos de los mejores ejemplos mundiales remanentes de praderas de pastos orientales, sabanas de roble, bosques abiertos de roble y humedales de pradera. Chicago Wilderness es más de 81,000 ha de áreas protegidas en la matriz urbana y suburbana. También es el nombre de una coalición de más de 110 organizaciones dedicadas a la supervivencia de esas tierras naturales. La salud a largo plazo de estas comunidades amenazadas depende del manejo adecuado de las tierras, más extensas y restaurables, que rodean y conectan a los fragmentos de hábitat de alta calidad. La información crítica para el éxito de los esfuerzos de conservación en la región incluye: (1) un mapa actualizado de la vegetación de Chicago Wilderness con suficiente detalle para que la definición de metas cuantitativas para el plan de recuperación de la región sea posible; (2) cuantificación de la fragmentación de las comunidades naturales y (3) patrones de cambio de cobertura de suelo y sus efectos sobre la vitalidad de las comunidades amenazadas. Utilizamos datos multiespectrales del mapeador temático Landsat (octubre 1997) y verificaciones de campo asociadas para producir el mapa actualizado de vegetación. Con datos de percepción remota multitemporales (obtenidos en 1972, 1985 y 1997), derivamos los mapas de cobertura de suelo en la región en intervalos equivalentes en los últimos 25 años. El análisis de los modelos SIG revela una rápida aceleramiento del crecimiento urbano y suburbano en los últimos 12 años. Las imágenes de satélite proporcionan comparaciones visuales notables del uso y condición del suelo. También proporcionan bancos de datos referenciados geográficamente que hacen posible el rastreo de tendencias cuantitativas. Los datos de degradación y fragmentación del hábitat son la base biológica de metas cuantitativas para la restauración regional. [source]

A new method of vegetation,climate classification in China

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2008
Sun Yanling
Abstract Coefficient C is a synthetic index from the third correlative equation, which represents the state of moisture in a region and may be used for assigning vegetation zonality. The third correlative equation is a new equation concerning heat and water balance from knowledge of evaporation on land. In this article, coefficient C and accumulated temperature over 5 °C (AT5) are combined to predict the distribution of vegetation zones in China. Predictions of vegetation distribution are made using observational climate data interpolated into a 25 × 25 km grid. The overall impression from examining the resulting vegetation map is that the location and distribution of vegetation zones in China are predicted fairly well. Comparison between the predicted vegetation map and the vegetation regionalization map are based on Kappa statistics and indicate very good agreement for the cold,temperate coniferous forest zone, the subtropical evergreen broadleaved forest zone, and the temperate mixed coniferous,broadleaved forest zone. Agreement is good for the warm,temperate deciduous broadleaved forest zone, the temperate steppe zone, the temperate desert zone, and the Tibetan high-cold plateau zone. Agreement between the regionalization map and the produced map is fair for the tropical rainforest and monsoon forest zone. Compared with those produced by the Holdridge, Thornthwaite, Penman, and the Kira models, as well as the Budyko method, the Kappa statistics in this article are all better except for the cold,temperate (boreal) coniferous forest zone and the temperate desert zone. The results are particularly superior for the Tibetan high-cold plateau zone. Coefficient C provides important information for predicting the distribution of vegetation zones in China, and this article attempts to study vegetation,climate classification on a large scale using coefficient C and AT5. Copyright © 2007 Royal Meteorological Society [source]

Predicting avian patch occupancy in a fragmented landscape: do we know more than we think?

JOURNAL OF APPLIED ECOLOGY, Issue 5 2009
Danielle F. Shanahan
Summary 1.,A recent and controversial topic in landscape ecology is whether populations of species respond to habitat fragmentation in a general fashion. Empirical research has provided mixed support, resulting in controversy about the use of general rules in landscape management. Rather than simply assessing post hoc whether individual species follow such rules, a priori testing could shed light on their accuracy and utility for predicting species response to landscape change. 2.,We aim to create an a priori model that predicts the presence or absence of multiple species in habitat patches. Our goal is to balance general theory with relevant species life-history traits to obtain high prediction accuracy. To increase the utility of this work, we aim to use accessible methods that can be applied using readily available inexpensive resources. 3.,The classification tree patch-occupancy model we create for birds is based on habitat suitability, minimum area requirements, dispersal potential of each species and overall landscape connectivity. 4.,To test our model we apply it to the South East Queensland region, Australia, for 17 bird species with varying dispersal potential and habitat specialization. We test the accuracy of our predictions using presence,absence information for 55 vegetation patches. 5.,Overall we achieve Cohen's kappa of 0·33, or ,fair' agreement between the model predictions and test data sets, and generally a very high level of absence prediction accuracy. Habitat specialization appeared to influence the accuracy of the model for different species. 6.,We also compare the a priori model to the statistically derived model for each species. Although this ,optimal model' generally differed from our original predictive model, the process revealed ways in which it could be improved for future attempts. 7.,Synthesis and applications. Our study demonstrates that ecological generalizations alongside basic resources (a vegetation map and some species-specific information) can provide conservative accuracy for predicting species occupancy in remnant vegetation patches. We show that the process of testing and developing models based on general rules could provide basic tools for conservation managers to understand the impact of current or planned landscape change on wildlife populations. [source]

The impact of cattle ranching on large-scale vegetation patterns in a coastal savanna in Tanzania

JOURNAL OF APPLIED ECOLOGY, Issue 3 2003
M. W. Tobler
Summary 1The success of large-scale cattle ranching in African savanna vegetation has often been limited by problems of bush encroachment and disease (in particular trypanosomiasis spread by tsetse flies). Mkwaja Ranch, occupying an area of 462 km2 on the coast of Tanzania, is a recent example of a large ranching enterprise that failed within the savanna environment. It was closed in 2000 after 48 years of operation. In this paper we describe the main vegetation types of the area (excluding closed forest vegetation) and relate their patterns of distribution to the former use of the ranch for cattle. 2The study area comprised the former ranch and parts of the adjacent Saadani Game Reserve, which had not been grazed by cattle for many years and had never been used for large-scale ranching. Following field surveys, 15 distinct types of grassland and bush vegetation were defined and a vegetation map was created using a Landsat TM satellite image. A multispectral classification using the maximum likelihood algorithm gave good results and enabled all 15 vegetation types to be distinguished on the map. 3Two main spatial trends were detected in the vegetation. One was a large-scale decrease in the cover of bushland from the most intensively used parts of the ranch through more extensively used areas to the game reserve; this trend was attributed to differences in management history as well as to climatic and topographic factors. A second trend was a radial vegetation pattern associated with the enclosures where cattle were herded at night. High amounts of three bushland types [dominated by (i) Acacia zanzibarica, (ii) Dichrostachys cinerea, Acacia nilotica or Acacia mellifera and (iii) Terminalia spinosa] occurred in a zone between 300 and 2500 m from the paddocks, with a peak in bush density at about 900 m (mean value for 18 paddocks). In contrast, bushland dominated by Hyphaene compressa was scarce close to the paddocks and became more abundant with distance. There was also a radial trend in the grassland communities: close to the paddocks there was short grass vegetation containing many ruderals and invasive weedy species, while the tall grassland types with species such as Hyperthelia dissoluta and Cymbopogon caesius occurred further away in the areas less affected by cattle. 4Synthesis and applications. The intensive modern livestock ranching as practised on Mkwaja Ranch proved to be unsustainable both economically and ecologically. In the end, the biggest problem faced by the ranch managers was not controlling disease, as had originally been feared, but preventing the spread of bush on pasture land. The results of our study demonstrate just how severe the problem of bush encroachment was, especially in areas close to paddocks. An important lesson for management is that grazing patterns need to be taken into consideration when determining the sustainable stocking rate for an area. To reduce the risk of bush encroachment in grazing systems with focal points such as paddocks or watering points, stocking rates need to be lower than in systems with a more uniform grazing distribution. [source]

The Circumpolar Arctic vegetation map

JOURNAL OF VEGETATION SCIENCE, Issue 3 2005
Donald A. Walker
Abstract. Question: What are the major vegetation units in the Arctic, what is their composition, and how are they distributed among major bioclimate subzones and countries? Location: The Arctic tundra region, north of the tree line. Methods: A photo-interpretive approach was used to delineate the vegetation onto an Advanced Very High Resolution Radiometer (AVHRR) base image. Mapping experts within nine Arctic regions prepared draft maps using geographic information technology (ArcInfo) of their portion of the Arctic, and these were later synthesized to make the final map. Area analysis of the map was done according to bioclimate subzones, and country. The integrated mapping procedures resulted in other maps of vegetation, topography, soils, landscapes, lake cover, substrate pH, and above-ground biomass. Results: The final map was published at 1:7 500 000 scale map. Within the Arctic (total area = 7.11 × 106 km2), about 5.05 × 106 km2 is vegetated. The remainder is ice covered. The map legend generally portrays the zonal vegetation within each map polygon. About 26% of the vegetated area is erect shrublands, 18% peaty graminoid tundras, 13% mountain complexes, 12% barrens, 11% mineral graminoid tundras, 11% prostrate-shrub tundras, and 7% wetlands. Canada has by far the most terrain in the High Arctic mostly associated with abundant barren types and prostrate dwarf-shrub tundra, whereas Russia has the largest area in the Low Arctic, predominantly low-shrub tundra. Conclusions: The CAVM is the first vegetation map of an entire global biome at a comparable resolution. The consistent treatment of the vegetation across the circumpolar Arctic, abundant ancillary material, and digital database should promote the application to numerous land-use, and climate-change applications and will make updating the map relatively easy. [source]

Iteratio: calculating environmental indicator values for species and relevés

APPLIED VEGETATION SCIENCE, Issue 3 2010
W. J. Holtland
Abstract Question: Is it possible to translate vegetation maps into reliable thematic maps of site conditions? Method: This paper presents a new method, called Iteratio, by which a coherent spatial overview of specific environmental conditions can be obtained from a comprehensive vegetation survey of a specific area. Iteratio is a database application which calculates environmental indicator values for vegetation samples (relevés) on the basis of known indicator values of a limited number of plant species. The outcome is then linked to a digitalized vegetation map (map of plant communities) which results in a spatial overview of site conditions. Iteratio requires the indicator values of a minimum of 10,20% of the species occurring. The species are given a relative weight according to their amplitudes: species with a narrow range are weighted stronger, species with a broad range are weighted weaker. Conclusion: The method presented here enables a coherent assessment of site conditions on the basis of a vegetation survey and the indicator values of a limited number of plant species. [source]

Life on the edge , to which degree does phreatic water sustain vegetation in the periphery of the Taklamakan Desert?

APPLIED VEGETATION SCIENCE, Issue 1 2010
Helge Bruelheide
Abstract Questions: Do the vegetation-specific patterns in the forelands of river oases of the Taklamakan Desert provide clues to the degree to which a vegetation type depends on unsaturated soil moisture, brought about by extensive floodings, or phreatic water? Location: Foreland of the Qira oasis on the southern rim of the Taklamakan Desert, Xinjiang Uygur Autonomous Region, China. Methods: A vegetation map was prepared using a SPOT satellite image and ground truthing. Measurements of soil water contents were obtained from a flooding experiment and transformed into water potentials. Sum excedance values were calculated as the percentage of days on which different thresholds of soil water potentials were transgressed. Groundwater depth was mapped by drilling 30 groundwater holes and extrapolating the distances to the whole study area. Results: The vegetation was characterized by only six dominant or codominant species: Alhagi sparsifolia, Karelinia caspia, Populus euphratica, Tamarix ramosissima, Calligonum caput-medusae and Phragmites australis. The vegetation patterns encountered lacked any linear features typical of phreatophytes, thus not allowing direct conclusions on the type of the sustaining water sources. Soil water potentials never transgressed a threshold of pF 5 (,10 MPa) in horizons above the capillary fringe during periods without inundation, thus representing water not accessible for plants. Depth to the groundwater ranged between 2.3 and 17.5 m among plots and varied between 1.7 and 8.0 m within a plot owing to dune relief. The seven main vegetation types showed distinct niches of groundwater depths, corresponding to the observed concentric arrangement of vegetation types around the oasis. Conclusions: Inundation by flooding and unsaturated soil moisture are irrelevant for the foreland vegetation water supply. Although distances to the groundwater table can reach about 20 m, which is exceptionally large for phreatophytes, groundwater is the only water source for all vegetation types in the oasis foreland. In consequence, successful maintenance of oasis foreland vegetation will crucially depend on providing non-declining ground water tables. [source]

Spatial variability of above-ground net primary production in Uruguayan grasslands: a remote sensing approach

APPLIED VEGETATION SCIENCE, Issue 1 2010
S. Baeza
Abstract Question: How does above-ground net primary production (ANPP) differ (estimated from remotely sensed data) among vegetation units in sub-humid temperate grasslands? Location: Centre-north Uruguay. Methods: A vegetation map of the study area was generated from LANDSAT imagery and the landscape configuration described. The functional heterogeneity of mapping units was analysed in terms of the fraction of photosynthetically active radiation absorbed by green vegetation (fPAR), calculated from the normalized difference vegetation index (NDVI) images provided by the moderate resolution imaging spectroradiometer (MODIS) sensor. Finally, the ANPP of each grassland class was estimated using NDVI and climatic data. Results: Supervised classification presented a good overall accuracy and moderate to good average accuracy for grassland classes. Meso-xerophytic grasslands occupied 45% of the area, Meso-hydrophytic grasslands 43% and Lithophytic steppes 6%. The landscape was shaped by a matrix of large, unfragmented patches of Meso-xerophytic and Meso-hydrophytic grasslands. The region presented the lowest anthropic fragmentation degree reported for the Rio de la Plata grasslands. All grassland units showed bimodal annual fPAR seasonality, with spring and autumn peaks. Meso-hydrophytic grasslands showed a radiation interception 10% higher than the other units. On an annual basis, Meso-hydrophytic grasslands produced 3800 kg dry matter (DM) ha,1 yr,1 and Meso-xerophytic grasslands and Lithophytic steppes around 3400 kg·DM·ha,1·yr,1. Meso-xerophytic grasslands had the largest spatial variation during most of the year. The ANPP temporal variation was higher than the fPAR variability. Conclusions: Our results provide valuable information for grazing management (identifying spatial and temporal variations of ANPP) and grassland conservation (identifying the spatial distribution of vegetation units). [source]

Implications of 19th century landscape patterns for the recovery of Fagus crenata forests

APPLIED VEGETATION SCIENCE, Issue 2 2005
Shinya Ohtani
Abstract Questions: What is the effect of the 19th century (pre-industrialization) landscape pattern on the recovery of climax forests in cool-temperate mountain areas dominated by Fagus crenata (Japanese beech)? Location: Secondary forests on Mt. Daisen, western Japan. Methods: Vegetation patterns before and after industrialization were obtained from maps drawn in 1898 and 1979. Tree measurements were made in 12 plots in 1997. Correlation between current Fagus crenata dominance and forest edge in the 19th century was analysed using an S-shaped regression curve. Fagus juvenile density was counted in the plots, and distances from each plot to the five nearest mother trees were measured to determine the dispersal kernel. Results: Secondary grassland covered a substantial area in 1898, whereas forest covered most of the area in 1997. Fagus was dominant in places in the interior forest 100 years ago, and mature Fagus trees were absent in secondary forests that had been grasslands in 1898. The expected number of juveniles decreased to one individual per 100 m2 at 43.5 m from the mother tree. Conclusions: The pre-industrialization landscape greatly affected recovery of Fagus forest. Forests found on the 1898 vegetation map might have acted as refugia for Fagus. The limited dispersal ability of Fagus suggests that it would take many generations (several hundred years) for Fagus forests to recover at the centre of what had been grasslands in the 19th century. [source]

Enhancing a regional vegetation map with predictive models of dominant plant species in chaparral

APPLIED VEGETATION SCIENCE, Issue 1 2002
Janet Franklin
Abstract. Data from more than 900 vegetation plots surveyed in the evergreen shrublands of southern California were used to develop predictions of the distributions of eight dominant shrub species for a 3880 km2 region. The predictions, based on classification tree (CT) models, were validated using independent field data collected during a vegetation survey conducted in the 1930s. Presence and absence were correctly predicted an average of 75% of the time for the eight species. At the same time, these models minimized false positives, so that presence was predicted in the correct proportion of the cases for most species. The areal proportion of the landscape on which the species were predicted to occur was in the same rank order, and of the same magnitude, as their frequency (proportion of plots in which they occurred) within the field data sets. Predictive maps of species presence were overlaid and combined with an existing regional vegetation map. The shrub species ,assemblages' that resulted from this procedure had analogs with vegetation series defined using field data in previous studies. The resulting multiple species map will be used in a landscape simulation model of fire disturbance and succession. [source]

Landscape Patterns of Tropical Forest Recovery in the Republic of Palau,

BIOTROPICA, Issue 4 2001
Bryan A. Endress
ABSTRACT A GIS (geographic information systems) database was constructed from aerial photographs, a vegetation map, and topographic map data of the Ngeremeduu Bay Drainage Area (NBDA), Palau, to examine relationships between upland land cover dynamics, environmental variables, and past land use. In 1992, 82.9 percent of the NBDA was forest, 16.6 percent was grassland, and 0.5 percent consisted of village areas. Between 1947 and 1992, there was a 11.2 percent reduction of grassland area primarily due to a 10.9 percent increase in forest cover. These land cover changes led to larger, more continuous stretches of forest and numerous, highly fragmented grassland patches. Significant relationships (P 0.001) were found between the spatial distribution of forest and grassland cover and slope, elevation, soil pH, and percent soil organic matter. These patterns, however, may have resulted from past farm site selection rather than from ecological relationships. Our results indicate that areas of forest expansion were significantly (P 0.001) associated with the location of abandoned agricultural communities. In addition, over 92 percent of areas of forest expansion occurred within 100 m of established forest. These results suggest that the proximity of established forest facilitate forest recovery following human disturbance. [source]

Assessing the relationship between forest types and canopy tree beta diversity in Amazonia

ECOGRAPHY, Issue 4 2010
Thaise Emilio
Planning of conservation priorities has often taken mapped forest types as surrogates for biological complementarity. In the Brazilian Amazon, these exercises have given equal weight to each forest type as if they were all equally distinct. Here, we examine floristic similarity between forest types to assess the reliability of vegetation maps as a surrogate for canopy tree-community composition. We analyzed floristic differences at the genus level between twelve Amazonian forest types using 1184 one-hectare inventories of large trees with three complementary approaches. First, we compared a map of floristic composition, from a uni-dimensional NMDS ordination of the inventories, with a map of coarser-level forest types commonly recognized as distinct by classification systems across Amazonia. Using Mantel and means-difference tests, we next examined the distance-decay of floristic similarity for all paired samples and for the pairs drawn from within and between twelve more finely divided forest types. Finally, we examined the degree of floristic separation of each pair of the twelve forest types using non-parametric analysis of variance. Maps of floristic composition and coarse-level forest types were highly congruent. At the finer level of classification, similarity was only slightly higher when pairs were drawn from the same versus from different forest types. This was true for all geographic distances. Nonetheless, eighty percent of the 66 paired combinations of forest types were significantly different in the unreduced genus-space and nearly half showed little or no overlap in a two-dimensional ordination. Three types were most distinct from all others: white sand, seasonally dry, and bamboo-dominated forests. Here, we show that forest types exhibit variable degrees of separation. For this reason, treating all fine-level forest types as equally distinct results in poor representation of canopy tree beta diversity. We recommend explicitly considering the degree of floristic separation between all forest types , as presented here for Amazonian flora , as a way to improve the use of this biodiversity surrogate. [source]

Iteratio: calculating environmental indicator values for species and relevés

Landscape-scale detection and mapping of invasive African Olive (Olea europaea L. ssp. cuspidata Wall ex G. Don Ciferri) in SW Sydney, Australia using satellite remote sensing

APPLIED VEGETATION SCIENCE, Issue 2 2009
P. Cuneo
Abstract Question: Is satellite imagery an effective tool for mapping and examining the distribution of the invasive species Olea europaea L. ssp. cuspidata at a regional landscape scale? Location: Southwest Sydney, Australia. Methods: Remote sensing software was used to classify pixels of Olea europaea L. ssp. cuspidata (African Olive) and major vegetation types from satellite imagery, using a "supervised classification" technique across a 721 km2 study area in the Cumberland Plain region of western Sydney. A map of African Olive distribution was produced from the image analysis and checked for accuracy at 337 random locations using ground observation and comparison with existing vegetation maps. The African Olive distribution data were then used in a GIS analysis with additional spatial datasets to investigate the relationship between the distribution of African Olive and environmental factors, and to quantify the conservation threat to endangered native vegetation. Results: A total area of 1907 ha of dense African Olive infestation was identified, with an omission error of 7.5% and a commission error of 5.4%. African Olive was found to occur on the steepest slopes (mean slope 14.3°) of the vegetation classes examined, with aspect analysis identifying a high prevalence on south- and southwest-facing slopes. The analysis also quantified the level of African Olive infestation in endangered ecological communities, with Western Sydney Dry Rainforest (25% affected) and Moist Shale Woodland (28% affected) identified as most vulnerable to African Olive invasion. Conclusion: The distribution of African Olive can be efficiently mapped at a landscape scale. This technique, used in association with additional spatial datasets, identified African Olive as a significant environmental weed in SW Sydney, occupying a greater area than previously recognised and threatening several endangered native vegetation communities. [source]

Long-term effects of nitrogen deposition on vegetation in a deciduous forest near Munich, Germany

APPLIED VEGETATION SCIENCE, Issue 3 2007
M. Bernhardt-Römermann
Vascular plants: Wisskirchen & Haeupler (1998); bryophytes: Koperski et al. (2000) Abstract Question: What are the main reasons for changes in the spatial distribution of vegetation types during the last four decades? Location: Isolated small deciduous forest; surrounded by farmland in the northeast of Munich (Germany). Methods: Based on sequential vegetation mapping from the last four decades the spatial development of the vegetation was analysed. Additionally, environmental parameters (soil parameters, PAR, N-deposition) have been analysed to describe the different vegetation types. Results: By linking the vegetation types to environmental parameters, it was possible to identify N-deposition as the most important factor for the changes. In the 1960s to 1980s the replacement of vegetation types adapted to N-poor conditions by N-rich vegetation was very fast. A vegetation type containing species signifying soil impoverishment vanished totally, another vegetation type indicating nutrient poor conditions decreased dramatically. However, since 1985 up to now the decrease of N-poor vegetation types has slowed, but is still ongoing. As a reason for the decreased rate of replacement, we stressed changes in the vertical structure: From 1961 to 1985 both N-deposition as well as changes in vertical vegetation structure seem to be important. Since 1985 up to now only minor changes in vertical structure could be found; changes are mainly due to N-availability. Conclusion: In this paper, the limitations of different methods to detect vegetation changes are discussed. We focus on the potentials of historical vegetation data and vegetation maps. It is shown that valuable information on N-induced vegetation changes can be retrieved from historical vegetation data. [source]

Soil fertility evolution and landscape dynamics in a Mediterranean area: a case study in the Sant Llorenç Natural Park (Barcelona, NE Spain)

AREA, Issue 2 2009
Jordi Nadal
The cartography of land covers was used to study fertility and soil evolution in a mountainous Mediterranean area during the anthropocene period (Crutzen P J 2002 Geology of mankind Nature 415 23). The aim was to determine changes in fertility as agricultural lands were abandoned in the 14 000 hectare area that constitutes Sant Llorenç del Munt Natural Park in a pre-coastal Catalan mountain range (north-eastern Iberian Peninsula). The analysis of land covers using vegetation maps, orthorectified images and aerial photography has allowed us to differentiate six vegetation groups: holm-oak wood, pine grove, oak wood, scrub, active agricultural fields and abandoned agricultural fields. The anthropic covers over the past 100 years were subdivided into five categories: active fields and those abandoned over four time periods. Study variables include field shape (concave, convex, flat), orientation (north, south) and slope (ranging from 12º to 24º). The parameters used for the physical-chemical soil analysis included organic material, phosphorous and potassium; fertility was classified based on groups, types and classes. The results indicate that even when the visual appearance of certain landscapes is similar, the edaphic characteristics may be very different. Changes induced by human disturbance share this phenomenon. Therefore, land management should be considered globally, taking into account vegetation, soils and water as interdependent factors, since it is their interaction that produces landscape and most affects its evolution over time. [source]