ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00001.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.tb00002.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

We now recognize that humans have the power to alter the planet irreversibly, on a global scale. Humans must be concerned with the condition of the planet that is passed to future generations.2

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA general model is presented describing ecosystem degradation to help decide when restoration, rehabilitation, or reallocation should be the preferred response. The latter two pathways are suggested when one or more “thresholds of irreversibility” have been crossed in the course of ecosystem degradation, and when “passive” restoration to a presumed predisturbance condition is deemed impossible. The young but burgeoning field of ecological restoration, and the older field of rehabilitation and sustainable range management of arid and semiarid lands (ASAL), are found to have much in common, especially compared with the reallocation of lands, which is often carried out without reference to pre‐existing ecosystems. After clarifying some basic terminology, we present 18 vital ecosystem attributes for evaluating stages of degradation and planning experiments in the restoration or rehabilitation of degraded ecosystems. Finally, we offer 10 hypotheses concerning ecological restoration and rehabilitation as they apply to ASAL and perhaps to all terrestrial e

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAdequately evaluating the success of coastal tidal marsh restoration has lagged behind the actual practice of restoring tidally restricted salt marshes. ASpartina‐dominated valley marsh at Barn Island Wildlife Management Area, Stonington, Connecticut, was tidally restricted in 1946 and consequently converted mostly toTypha angustifolia.With the re‐introduction of tidal flooding in 1978, much of the marsh has reverted toSpartina alterniflora.Using a geographical information system (GIS), this study measures restoration success by the extent of geographical similarity between the vegetation of the restored marsh and the pre‐impounded marsh. Based on geographical comparisons among different hydrologic states, pre‐impounded (1946), impounded (1976), and restored (1988) tidal marsh restoration is a convergent process. Although salt marsh species currently dominate the restored system, the magnitude of actual agreement between the pre‐impounded vegetation and that of the restored marsh is only moderate. Further restoration of the salt marsh vegetation may be limited by continued tidal restriction, marsh surface subsidence, and reduced accretion rates. General trends of recovery are identified using a gradient approach and the geographic pattern’ of vegetation change. In the strictest sense, if restoration refers only to vegetation types that geographically replicate preexisting types, then only 28% of the marsh has been restored. Restoration in a broader sense, however, representing the original salt marsh vegetation regardless of spatial position, amounts to 63% restored. Unrestored marsh, dominated byTypha angustifoliaandPhragmites australis, remains at 37%. By emphasizing trends during vegetation recovery, this evaluation technique aims to understand the restoration process, direct future research goals, and ultimately aid in future restorati

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA series of experiments designed to demonstrate the potential of using managed, attached algal production to permanently remove excess phosphorus from agricultural run‐off is described. The experiments were carried out on a secondary canal in the New Hope South region of the Florida Everglades Agricultural Area from October, 1991, to May, 1992. Natural algal populations of periphyton, including species of the generaCladophora, Spirogyra, Enteromorpha, Stigeoclonium, and a variety of filamentous diatoms such asEunotiaandMelosira, were grown on plastic screens in raceways, under a wave surge regime. Considerable biomass production of algae occurred, and the resulting algal canopy also trapped plankton and organic particulates from the water column. A seven‐ to eight‐day harvest interval was determined to be optimal, and both hand harvesting and vacuum harvesting were employed. The vacuum device is applicable to large scale‐up. In source water having total phosphorus concentrations of 0.012–0.148 ppm, mean macro‐recovery dry biomass production levels of 15–27 g/m2/day were achieved. The lower rates occurred in the winter, the higher rates in the late spring. Two techniques were employed to reduce losses of fine material at harvest during the March to May period. Gravity sieving increased mean dry production levels to 33–39 g/m2/day. The mean phosphorus content of harvested biomass ranged from 0.34% to 0.43%. Total phosphorus removal rates during the spring period of average solar intensity and low nutrient supply, by methods demonstrated in this study, ranged from 104 to 139 mgTP/m2/day (380–507 kgP/ha/year). Over the incoming nutrient range studied, phosphorus removal was independent of concentration and was 16.3% of total phosphorus for 15 m of raceway. Up‐stream‐downstream studies of overflowing water chemistry (total P, total dissolved ‐P, orthophosphate ‐P) showed highly ‐significant reductions of all phosphorus species. Total phosphorus reduction closely correlated with phosphorus yield from biomass removal. Yearly, minimum phosphorus removal rates are predicted that are 100–250 times that achieved both experimentally and in long‐term, large‐area wetland systems. Engineering scale‐up to systems of

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractExperiments were conducted in the field and the greenhouse to determine whether vesicular‐arbus‐cular mycorrhizae affect growth and competition between the native perennialStipa pulchraand the introduced annualAvena barbata.Soils in the greenhouse were steam‐sterilized, and in the field they were treated with the fungicide benomyl.Stipa pulchrashowed decreased shoot dry mass and increased root mass when inoculated, whileA. barbatashowed the opposite response, increased shoot mass and decreased root mass. MycorrhizalA. barbataalso produced more seeds. Mycorrhizae did not alleviate the negative effects of competition ofA. barbataonS. pulchra, as has been demonstrated for other pairs of weedy and nonweedy species. The same three species of mycorrhizal fungi were present in annual and perennial grasslands, but their relative composition was different. When inoculum from the two grassland types were tested in the field, the fungal species began to revert within five months to the species composition found in grasslands of the host plant. This indicates that, once annual grassland has been revegetated with the nativeS. pulchra, the original fungal species composition may return relatively quickly. WhereA. barbatadominates, inoculation with mycorrhizal fungi alone will not suffice for establishingS. pulchra, and the usual practices for control of weed competition need to be emp

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractGlasshouse trials, using trickle irrigation and increasing levels of NaOH‐induced alkalinity, identified species that could be expected to tolerate the high‐pH conditions of bauxite processing waste residue sites. Of 29 taxa tested, the most tolerant wereCasuarina obesa, Melaleuca lanceolata, M. armillaris, M. nesophila, Eucalyptus loxophleba, E. halophila, E. platypus, Tamarix aphylla, and a particular clone ofE. camaldulensis; E. spathulata, E. tetragona, E. preissiana, E. gomphocephala, E. diptera, and E. occidentalisproved to be relatively sensitive to severe alkaline conditions. Tolerance appeared to relate to an ability to maintain root membrane function, nutrient uptake balance, and ultimately root tissue structure while under increasing levels of alkalinity stress. Species normally inhabiting alkaline soils tended to have increased growth rates in nutrient irrigation conditions between pH 8 and 10 compared with control plants irrigated with nutrient solutions of pH values near 7.4. However, once the irrigation solutions reached pH 12 and the buffering capacity of the soil appeared to be exceeded, the condition of susceptible plants rapidly declined and death followed. Sensitive plants initially showed symptoms related to nutrient deficiency, followed by wilting and death as the root systems failed. Field trial conditions in the bauxite residue impoundments at Kwinana, Western Australia, include soils with pH values as high as 11.00. In general, the relative survival and growth of seedlings after eight months were predicted by the response under glasshouse trial conditions. Appropriately designed stress trials can be important ecological techniques in choosing species most capable of surviving difficult environmental conditions in the rehabilitation of damaged landsca

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractResults are presented using vegetative shoots and bryophyte sods to restore floristically impoverished high arctic wet sedge‐moss meadows that had suffered intense damage from vehicle activity during the period 1960–1967. Clonal transplants ofCarex aquatilisvar.stans, a native sedge, were planted with and without bryophyte sods in vehicle ruts in 1972. After nearly two decades, there was less Carex cover in the planted ruts with flowing water than in the contiguous controls. This pattern was slightly reversed in planted plots with standing water. Reinvasion ofEriophorum angustifoliumoccurred in treated ruts, but cover was less in both treatments than in controls in 1990. The unexpected recruitment ofEriophorum scheuchzerifrom the seed bank in moss‐sodded plots is discussed in terms of its local and regional importance. Total plant cover in restored ruts was nearly equal to that of controls, but biomass was somewhat less than that in control plots. Plots with bryophytes were environmentally distinct, due primarily to increases in organic mat depth relative to controls. After 18 years, restoration efforts resulted in increased plant cover in treated ruts compared to naturally recovering ruts.The composition of no two patches of vegetation is precisely the same [and] neither are the seed banks. Successsion on different patches of disturebed ground in the same locality frequently proceeds quite differently because of such differences.—J. Miles,Vegetation Dynami

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00009.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Books reviewed in this article:The Earth in Transition: Patterns and Processes of Biotic Impoverishment.A collection of papers from a symposium held in Woods Hole, Massachusetts, October 1986. George M. Woodwell, editorRestoration of Aquatic Ecosystems: Science, Technology, and Public Policy.National Research Council.

ISSN:1061-2971    

DOI:10.1111/j.1526-100X.1993.tb00010.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY