摘要:

AbstractA numerical floristic analysis of samples across a monsoon forest‐savanna boundary, from an area that had been actively protected from fire for 15 years, at Weipa, northern Australia, revealed three communities: (i) a monsoon forest with a low closed canopy composed mainly of tree species with extra‐Australian tropical affinities and a sparse ground layer; (ii) an ecotone with a distinct closed microphyll shrub layer beneath the open canopy of savanna trees; and (iii) a savanna dominated byEucalyptus tetrodonta. The development of the ecotone has occurred since fire protection and is of limited extent within the fire protected block. The monsoon forest occurred on soils with significantly higher concentrations of bauxitic pisoliths than the other two communities. Soils under the monsoon forest had significantly higher concentrations of total K, S, C, N, exchangeable K and Ca, and higher pH and electrical conductivity than for soils of either of the other communities. A positive relationship between woody basal area and concentrations of surface soil total P, N, C, exchangeable Ca, CEC and gravel was detected across a 20 m transect from the ecotone community into the savanna. The invasion of monsoon forest seedlings was greatest in the ecotone, with few occurring in the savanna. It appears that the expansion of the monsoon forest requires the development of a layer of shrubs. The mechanism of this facilitation is unclear, although the possible role of nutrient enrichment by the shrubs requires further investigat

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1991.tb01486.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractTo assess the ecological consequences of selective logging in the major rainforest areas in Australia, past studies are reviewed with respect to the following: recovery of stand structure; regeneration capacity; individual tree growth and species composition of stands; hydrologie impact; floristics; wildlife; soil nutrient levels; fire susceptibility; and incursion of weeds and diseases.Although rainforest logging has become a sensitive issue in the community and its effects are of concern to ecologists, relatively few scientific studies of selective logging have been published. Thus, the full nature and extent of ecological changes to Australian rainforests due to this form of disturbance cannot yet be determined. However, some cautious interpretation of the studies that have been completed is possible.Following a single selective logging, the changes indicated by individual studies often appeared to be relatively minor. It is suggested that many of these effects are not extensive or irreversible and might not persist beyond structural recovery of the rainforest. However, two changes were identified as likely to persist beyond structural recovery. These are: a post‐logging difference in the proportional representation of major overstorey tree species and a reduction in the numbers of large‐diameter trees.Further, results indicate that more extensive and longer‐lasting changes may result from multiple selective loggings, especially if the time between successive loggings is short. Even with light logging intensities, a conservative interval of at least 60 years between selective loggings, to allow canopy and below‐canopy conditions to be restored, is indicated.Apart from disturbance frequency, the studies reviewed raise questions as to whether long‐term natural disturbance effectsper seare distinguishable from long‐term selective logging effects. A need for further work is highlighted.Overall, there appears to be a distinction between the recovery capability of the more northerly mainland rainforests and those of Tasmania. Slower growth in the more southerly rainforests, compounded by a geographical susceptibility to summer drought, increases the possibility of fire damage following select

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1991.tb01487.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1991.tb01488.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Book Reviewed in this article:Threatened Plants of New ZealandCatherine M. Wilson and David R. GivenThe Greenhouse EffectA. Henderson‐Sellers and R. Blo

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1991.tb01489.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY