ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00020.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractWe studied the use of mineland wetlands by birds and the relationship between avian communities and wetland characteristics. Data were collected from 20 wetlands in Pike County, Indiana, and included wetland size, depth, water conductivity and salinity, aquatic macroinvertebrate abundance, vegetation, and bird use. Principal component analysis showed that physical variables could be explained by two principal component scores and that wetlands could be grouped on the basis of size and conductivity. Principal component analysis could not reduce vegetation variables to fewer principal component scores, meaning that wetland vegetation characteristics were independent of one another and did not show any trend. Most wetlands had low invertebrate density, and wetlands with higher invertebrate density had low invertebrate diversity. Wetlands with similar habitat characteristics (physical, vegetative, and invertebrate) did not necessarily show similarities in bird assemblages. Bird similarity index values ranged from 0 to 59%, implying that each wetland has its own bird community. Stepwise multiple regression analysis (α= 0.05) relating bird use and habitat characteristics showed that bird species richness increased with the species richness of submergent vegetation and was correlated negatively with the species richness of emergent vegetation. There was no significant relationship between bird species richness or bird species diversity and wetland size. The number of species within different avian guilds correlated with different habitat characteristics. The species richness of submergent plants was a factor that correlated positively with the number of species of several guilds (dabblers, wading birds, and plunge divers). Wetland age was not a factor that determined bird use

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00021.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe composition and structure of ant communities were used to assess the success of the preliminary restoration program at Ranger uranium mine in the seasonal tropics of northern Australia. Ants were surveyed at eight sites, including two relatively undisturbed control sits, within the Ranger lease. The revegetated sites represented a range of variables likely to influence restoration success: revegetation age (two, four, and eight years), proximity to undisturbed sites (which act as potential sources of recolonization), and burning treatment. Revegetation at most sites was dominated by fast‐growing species ofAcacia.There was a clear succession of ant species across revegetated sites. Initial colonization was by species ofIridomyrmex, but as plant cover and litter development increased these were replaced by broadly adapted, opportunist species, especially the introducedParatrechina longicornis. Ant recolonization was very slow at isolated sites, with only 12 species present after eight years (the oldest site available). This compares with 21 species after only four years at a site located close to potential sources of recolonization. The ant community at this site, however, was very similar to that at another site located close to colonization sources, but eight years old. Ant succession therefore appeared to have stalled at this point, with species richness and composition bearing little resemblance to that at control sites. The heavy shade and litter produced by acacias were considered to be the major impediment to further change. Results from a site that had undergone a prescribed burn after two years, thereby breaking dominance by acacias and allowing for the establishment of a wide variety of plant taxa, suggest that such management practices may promote further colonization by ant specie

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00022.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA model of ecosystem degradation and three possible responses to it—restoration, rehabilitation, and real‐location—is applied to ongoing projects in the arid mediterranean region of southern Tunisia, the subhumid mediterranean region of central Chile, and the semiarid tropical savannas of northern Cameroon. We compare both nonhuman and human determinants of ecosystem degradation processes in these contrasted regions, as well as interventions being tested in each. A number of quantifiable “vital ecosystem attributes” are used to evaluate the effects of ecosystem degradation and the experimental responses of rehabilitation on vegetation, soils and plant‐soil‐water relations. We argue that attempts to rehabilitate former ecosystem structure and functioning, both above‐ and below ground, are the best way to conserve biodiversity and insure sustainable long‐term productivity in ecosystems subjected to continuous use by people in arid and semi‐arid lands of “the South.” The success of such efforts, however, depends not only on elucidating the predisturbance (or slightly disturbed) structure and function of the consciously selected “ecosystem of reference,” but also on understanding and working with the socioeconomic, technical, cultural, and historical factors that caused the deg

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00023.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractGrass seeding is widely used for erosion control, but its consequences for soil and regeneration following fire have been measured only infrequently. This study investigates the effect of grass seeding on the type and extent of plant cover; soil moisture percentage; and moisture stress, survival, growth, and root‐tip and mycorrhiza formation ofPinus lambertiana(sugar pine) seedlings in a clearcut intensely burned by wildfire. One‐year‐old containerized sugar pine seedlings were planted in seeded and nonseeded areas in Spring 1988 and 1989 in the Longwood Fire area of southwest Oregon. In 1988, tree seedlings in grass‐seeded plots experienced intense competition from the grass, reduced root‐tip and mycorrhiza formation, low levels of soil moisture to meet evapotranspirational demand, high levels of mortality, and reduced growth. In 1989, however, the opposite was true: tree seedlings in nonseeded plots experienced competition from invading native annuals and perennials, low levels of soil moisture in summer, and higher levels of mortality. The studies we report here further indicate that, in an area characterized by extended summer drought, annual ryegrass impeded regeneration of sugar pine during the first season following the fire. Native species cover and richness have been significantly reduced in the seeded area and may affect long‐term soil stability, productivity, and conifer restoration. Seeding of annual ryegrass at high rates under these conditions would seem

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00024.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSoil microbial activity and soil nutrients were monitored on a revegetated coal surface mine in southwestern Wyoming from the initial planting in 1982 through 1987. Total soil nitrogen (N) and organic matter did not change during this period. However, despite no changes in available phosphorus (P) concentrations, the total P declined over 50% during the five‐year period, with no apparent reduction in the loss rates. The greatest loss was in the bound inorganic P pool. Moisture appeared not to limit microbial mass‐C. Microbial mass‐C was higher under shrubs than in interspaces and increased with time. Total organic matter did not increase. Thus, the ratio of microbial mass‐C to organic matter‐C increased during the study period. This suggests that the input of readily decomposable substrate may limit microbial activity. During the study period, all above‐ground litter was removed by wind. Root production in the surface soils was low and highly variable and, in this habitat, probably did not contribute largely to the organic matter status. These data suggest that despite an apparent recovery of many parameters used to indicate reclamation or restoration success, the soil‐bound P pools could be undergoing a loss. Microbial‐C and organic matter changes indicate a system that is not approaching equilibrium within the required monitoring period of most restoration efforts. These parameters could eventually reduce the recovery potential of

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00025.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00026.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Books reviewed in this article:Reintegrating Fragmented Landscapes towards Sustainable Production and Nature Conservation.R. J. Hobbs and D. A. Saunders. editorsRestoring Acid Waters: Loch Fleet 1984–1990.G. Howels, and T.R.K. Dalziel, edito

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00027.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY