Showing papers on "Vegetation (pathology) published in 1985"

Fractal dimension of vegetation and the distribution of arthropod body lengths

Abstract: Following Mandelbrot1, recent studies2–6 demonstrate that some natural surfaces are fractal. Here we show that transects across vegetation are fractal, and consider one possible consequence of this observation for arthropods (mainly insects) living on plant surfaces. An important feature of a fractal curve or surface is that its length or area, respectively, becomes disproportionately large as the unit of measurement is decreased1. This suggests that if vegetation has a fractal structure, there is more usable space for smaller animals living on vegetation than for larger animals. Hence, there should be more individuals with a small body length than a large body length. We show that this is the case, and that relative numbers of small and large individual arthropods collected from vegetation are broadly consistent with theoretical predictions originating from the fractal nature of vegetation7 and individual rates of resource utilization.

Bottomland Vegetation Distribution along Passage Creek, Virginia, in Relation to Fluvial Landforms

Abstract: Persistent distribution patterns of woody vegetation within the bottomland forest of Passage Creek, Virginia, were related to fluvial landforms, channel geometry, streamflow characteristics, and sediment—size characteristics. Vegetation patterns were determined from species presence as observed in transects and traverses on landforms developed along the stream. Distinct species distributional patterns were found on four common fluvial geomorphic landforms: depositional bar, active—channel shelf, floodplain, and terrace. Independent hydrologic characteristics (flow duration and flood frequency) were determined for each of the landforms. Vegetation data were analyzed by binary discriminant analysis, principal components analysis, and detrended correspondence analysis. Results and related field observations suggest that certain species are significantly associated with specific fluvial landforms. Vegetation patterns appear to develop more as a result of hydrologic processes associated with each fluvial landform rather than from sediment—size characteristics. Flood disturbance may be an important factor in maintaining the vegetation patterns, which may therefore be used as indicators for particular hydrogeomorphic site conditions.

North American vegetation patterns observed with the NOAA-7 advanced very high resolution radiometer. [North America

Abstract: Spectral vegetation index measurements derived from remotely sensed observations show great promise as a means to improve knowledge of land vegetation patterns. The daily, global observations acquired by the Advanced Very High Resolution Radiometer, a sensor on the current series of U.S. National Oceanic and Atmospheric Administration meteorological satellites, may be particularly well suited for global studies of vegetation. Preliminary results from analysis of North American observations, extending from April to November 1982, show that the vegetation index patterns observed correspond to the known seasonality of North American natural and cultivated vegetation. Integration of the observations over the growing season produced measurements that are related to net primary productivity patterns of the major North American natural vegetation formations. Regions of intense cultivation were observed as anomalous areas in the integrated growing season measurements. These anomalies can be explained by contrasts between cultivation practices and natural vegetation phenology. Major new information on seasonality, annual extent and interannual variability of vegetation photosynthetic activity at continental and global scales can be derived from these satellite observations.

Relationships between soil and vegetation in a tropical rain forest in French Guiana

Abstract: We describe a new method to observe and map morphological and functional characteristics of soil. Drainage and surface hydromorphy were mapped in eleven plots including 16.8 hectares. In the same plots, all trees over 20 cm DBH were inventoried. Structural data of the vegetation are correlated to soils characteristics as well as the frequencies and densities of 32 taxa.

Vegetation succession on the dunes near Oostvoorne the Netherlands since 1934, interpreted from air photographs and vegetation maps

Abstract: The vegetation succession on the dunes near Oostvoorne, The Netherlands has been followed by means of a novel combination of repeated large-scale vegetation mapping and air photograph interpretation. Vegetation units have been discerned on the formation level because these could be distinguished fairly easily on the photographs and because the rates of change are appropriate to the time interval chosen. Nineteen formations were distinguished. Five 1:6250 maps were constructed, reflecting the formation pattern in 1934, 1943, 1959, 1972 and 1980. An overlay with 2736 grid points at 25 m field distance was used to quantify changes in the formation pattern.

Hawai'i's Terrestrial ecosystems : preservation and management

Abstract: 3 Introduction 4 Methods 6 Background on Hawai'i Forest Bird Survey 6 Vegetation Mapping 8 Assessment of Status of Native Vegetation 9 Analysis of Endangered Species Data 9 Results 10 Current Status of Major Native Vegetation Units 10 Summary of Endangered Species Found Within Study Area 16 Discussion 17 Factors Responsible for Degradation of Native Habitats 17 Recovery Potential for Damaged Native Ecosystems 18 Conservation Strategies 18 Acknowledgements 19

Vegetation and soils of burrowing owl nest sites in Conata Basin, South Dakota

Abstract: On caracterise la vegetation et les sols des Terriers abandonnes de Cynomys ludovicianus et utilises pour nidifier par Athene cunicularia et on les compare avec ceux des terriers non occupes par l'oiseau

Further investigation on the causes of disorder of the coastal vegetation in the park of San Rossore (central Italy)

Abstract: The deterioration of the pine-woods on the tyrrhenian coast of Italy can be ascribed to a synergism between surfactants and sodium chloride. The destruction of epieuticular wax in pine needles has been revealed by the electron microscope. Data on acid rain are reported.