ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1994.tb00052.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1994.tb00053.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractExtensive areas of the tropics have been converted into pasture for cattle ranching. Frequently, abandoned pasture does not revert to forest. The goal of this project was to identify barriers to lowland moist forest regeneration in highly degraded grasslands in the Sierra Nevada de Santa Marta, Colombia. The barriers we considered were seed source, seed predation, competition with grasses, microclimate and soil limitations on plant growth, and fire. Seed dispersal into the grasslands is limited to within 10 meters of forest fragments, but this barrier can be overcome by sowing seeds and planting seedlings and by establishing perches to attract dispersers. In these degraded grasslands, seed predation was lower than in the adjacent forest patches, and there was no evidence that grasses inhibited the establishment of woody species. The most important barrier was the severe degradation of the soils. In much of the area, theAandBhorizons have been eroded away, leaving saprolite at the soil surface. Seedlings of two fast‐growing pioneer species,Ochroma pyramidaleandCochlospermum vitifolium, grew to a maximum height of only 2.5 and 12 cm, respectively, during the first eight months. The slow plant growth in the degraded grassland soils compared to forest soils was associated with lower levels of cation‐exchange capacity, calcium, magnesium, and potassium. Even if these barriers could be overcome, the frequent and extensive use of fire in the region must be controlled to avoid killing established woody pla

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1994.tb00054.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractBiological resources can be more usefully incorporated into many aspects of restoration ecology. During the planning and design stage, the wide genotypic variation in natural plant populations must be recognized and exploited. This will ensure that genotypes used on a site are best adapted to local conditions and have a greater probability of survivorship than arbitrarily chosen material. Also, certain unusual genotypes can be located using the principles of evolutionary ecology and can be installed in areas with extreme conditions, such as soils contaminated with heavy metals, in areas where rapid colonizing ability (high seed set and/or clonal growth) is particularly advantageous, or where soils are of poor quality. Similarly, where high herbivore pressure is a threat to restoration, genotypes that are well defended, chemically or mechanically, against animal enemies should be selected to initiate the restoration process. The nursery industry can be encouraged to supply an ecologically wider selection of material for restoration, originating from local biological reserves and natural habitats. During the management phase of a restoration, local natural habitats are critical as reservoirs of biological control agents, seed sources for plant species, and members of higher trophic levels and additional plant species needed during succession. Mutualists such as pollinators, seed dispersers, and mycorrhizal fungi are vital to the success of a restoration project, and these must invade from nearby natural habitats or must be deliberately introduced. During the evaluation phase of restoration, local natural areas should be used as templates of community composition and structure from which one measures success. A functioning restoration project will interact biologically with surrounding areas, the exchange of species and genes being particularly important. Analysis of the microbial and invertebrate communities that have invaded the installed plant community may be useful and accurate determinants of ecological function. For these latter stages of the restoration process, the value of preserving local habitat remnants is high and complements their usefulness as a source of ecologically precise material for installation.

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1994.tb00055.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe feasibility of measuring soil salinity with electromagnetic induction (EM) for determining riparian restoration potential was investigated on a 28‐hectare plot at the Bosque del Apache National Wildlife Refuge in central New Mexico. The plot was cleared of exoticTamarix chinensis(saltcedar), surveyed and gridded into 1370.2 hectare sections. Soil samples and EM measurements were taken at each section. We compared laboratory‐determined ECevalues from the soil samples with ECavalues calculated from the EM measurements using a model developed by Rhoades et al. (1990). Direct comparison of ECevalues determined from the two methods yields a low correlation due to sample‐size differences but the calculated ECawas able to accurately predict whether the measured ECewould lie above or below some threshold value. An assessment of general site suitability for riparian restoration with electromagnetic induction has proven to be a rapid, accurate, and cost‐effective alternative to intensive soil s

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1994.tb00056.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA study of spider (Araneae) communities was conducted in rehabilitated bauxite mines at the Jarrahdale mine site of Alcoa of Australia Ltd. and in the nearby native jarrah (Eucalyptus marginata) forest in southwest Western Australia. The study was conducted from March to August 1993 in five rehabilitated sites of different age and method of rehabilitation and in two forest sites. A variety of collection methods was used, including pitfall trapping, litter sampling, sweep netting, tree beating, and visual searching. These methods were the same as those carried out in a previous study of some of these areas in 1983. We collected 151 spider species belonging to 102 genera and 34 families. We examined the relationship between various habitat features, including the age and method of rehabilitation, of the spider communities present. It was found that leaf litter depth and cover and vegetation density had a significant positive influence on recolonization by the various spider guilds. The age and method of rehabilitation were found to influence different vegetational and habitat features; these, in turn, influenced the spider communities. Thus, the older a rehabilitated site the greater the species richness of both plants and spiders. We compared these results with those of the 1983 study to determine the spider succession of the aging rehabilitation. The spider communities and guild composition were found to change as the vegetation matured, from a dominance of pioneer species to a community of species requiring less harsh conditions. By comparison with the pre‐1983 rehabilitation, the latest method of rehabilitation increased the rate of recolonization by both plants and spider

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1994.tb00057.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractFire is a common but poorly understood disturbance in the forested ecosystems of the Sierra Madre Occidental of Mexico. In this study, fire history, forest structure (density, species composition, regeneration, forest floor fuels, herbaceous cover, and age of pines), and the dendrochronological tree‐ring record were measured at two unharvested 70‐ha pine‐oak sites near Ojito de Camellones, Durango, Mexico. Study sites were matched in slope, aspect, elevation, slope position, and plant composition, but they differed in fire history since 1945 and in forest structure. The long‐term mean fire intervals (MFI) for all fires at both sites up to 1945 were similar—4.0 years at Site 1 (1744–1945) and 4.1 years at Site 2 (1815–1945)—but Site 1 burned only three times at the site margins since 1945 while Site 2 had 9 fires that scarred two or more sample trees and 15 total fires since 1945. Density measurements and age and diameter distributions showed that Site 1 was dominated by numerous, younger, smaller trees (mean total basal area of 23.4 m2/ha and 2730 trees/ha), while Site 2 had fewer, older, larger trees (basal area of 37.2 m2/ha, 647 trees/ha). Large, rotten fuel loading and duff depth were also greater at Site 1. Because regeneration averaged 6200 stems/ha at Site 1 and 8730 stems/ha at Site 2 (no significant difference), forest density at Site 2 was not limited by regeneration capability. The distributions of overstory diameter and pine age at both sites indicate that tree establishment occurred in pulses, with the largest cohort of trees establishing at Site 1 following the 1945 fire. The dense regeneration and heavy fuel accumulation at Site 1 are likely to support a switch from the former low‐intensity fire regime to a high‐intensity, stand‐replacing fire across the site when the next suitable combination of ignition and weather occurs. Baseline quantitative information on fire frequency and ecological effects is essential to guide conservation or restoration of Madrean forests and may prove valuable for restoration of related fire‐dependent ecosystems that have experienced extended fire exclusion els

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1994.tb00058.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Books reviewed in this article:Perspectives on Biodiversity: Case Studies of Genetic Resource Conservation and Development.Christopher S. Potter, foci 1. Cohen, and Dianne Janczewski, editors

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1994.tb00059.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY