摘要:

AbstractEstimates of leaf damage by insect herbivores are presented for 25 species of mangrove plants, comprising canopy and understorey species. Leaf area loss was highly variable among the species sampled, with means ranging from 0.3 to 35.0% of expanded leaf area. There was also great variability amongst leaves within species, and the mean coefficient of variation for leaf loss from the 25 species was 266%. Of the 12 species sampled at more than one site in North Queensland, eight exhibited small, but significant, between‐site differences in herbivory. In general, it did not appear that height in the canopy influenced herbivory. For the dominant mangrove forest community type at Missionary Bay, an estimated mean of 2.1% of leaf production, or 11 g m‐2per year, entered the direct grazing pathway. This very low figure is compared with estimates from other studies on mangrove forests and estimates from a variety of Australian terrestrial fore

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00921.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractIn a 3 year study of the cattle egret at a heronry of 3500 nests in south‐east Queensland, 34% of eggs in 711 nests observed failed to survive to become fledglings (11 day old chicks). Fledgling mortality seemed much lower. The main sources of mortality were crow predation on eggs, failure of the incubated egg to develop fully, starvation of nestlings and tick infestation of nestlings. These were of about equal importance overall but their individual magnitudes varied considerably among the three seasons. The pattern of infestation of the cattle egret chick with the tickArgas (Persicargas) robertsiand the effect of this on chick health are described. An account is given of the other sources of morbidity also. The heronry appeared to be producing a net surplus of young despite these losse

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00922.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe hypothesis that stemflow is important in contributing to the nutrient requirements of nikau palmRhopalostylis sapidaindividuals is examined. Stemflow directs many times more sodium, potassium, calcium and magnesium to the base of the palm than is required for annual net production. There are three sources for nutrients found in stemflow: (1) atmospheric inputs (wet and dry deposition); (2) foliar leaching; and (3) alien litter leaching and decomposition. Sources I and 3 together, representing nutrient input, contribute substantially more nutrients than are required for net annual production in mature individuals.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00923.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractObservations in tropical lowland rainforests damaged by Cyclone Winifred on 1 February 1986 suggest that the disturbance has been followed by an unusual burst of flowering. Fifty‐four species of concurrently flowering shrubs and trees were recorded in early March along a 4 km road transect in a cyclone‐damaged forest. Approximately 80% of the smaller tree and shrub species observed were flowering. Twelve species which had flowered and fruited prior to the cyclone flowered again. Some species which normally flower following periods of partial or complete deciduousness in the drier months of the year flowered after being defoliated by the cyclone. Widespread defoliation of the rainforests, together with the hot, dry weather which followed the cyclone, exposed the understorey layers to abrupt increases in temperature, insolation, and water stress. It is postulated that these environmental changes may have effected the synchronization of flowering of a larger number of species than would normally occur. It is suggested that longterm changes in the species composition of the damaged forests as a result of coincidences of seed availability and regenerative space may oc

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00924.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractLitter decomposition, soil respiration and soil chemical and biochemical properties were examined at three contrasting sites in karri(Eucalyptus diversicolorF. Muell.) forest of south‐western Australia. The study sites were: a recently clearfelled area (site CF2) which had been subjected to a slash regeneration burn following clearing; a pole‐stand regrowth forest about 40 years old which had been regularly burnt by cool, prescribed fires (site RB40); and a pole‐stand regrowth forest about 40 years old which had remained unburnt for many years (site UB40).Leaf litter of uniform composition lost 40–54% of its original dry weight after decomposing for 82 weeks on the forest floor. A composite exponential model, with separate decay functions for labile and more resistant litter components, described rate of weight loss better than a simple exponential decay model. Labile components of litter were released at similar rates at the three sites. Decomposition of resistant litter components was slower (half‐life = 271 weeks) at the recently clearfelled site than at the two pole‐stand sites (half‐lives = 119 and 149 weeks). The order in which nutrients were released from decomposing litter, Na>Cl>K>Mg>S>Ca>N>P, was similar at each site. The rate of release of the more mobile elements Na, Cl, K, Mg and S, was also similar at each site. Changes in the amounts of Ca, N and P in decomposing litter differed between the three sites and the differences were related to the amounts of these nutrients in surface soil at each site.Annual soil respiration decreased in the order site CF2 = site UB40>site RB40. Seasonal variation in respired CO2was partly explained by variation in soil moisture and temperature. Soil carbohydrase activity at the recently clearfelled site was significantly lower than at the two well vegetated pole‐stand sites. The differences between sites in enzyme activities were related to differences in the amounts of organic C in surface soils of the three sites.The amount of organic C in surface soil (0–15 cm) was 25–36% lower at the recently clearfelled site than at the two well vegetated pole‐Stand sites. Site disturbance during clearing, and combustion of soil organic matter by the subsequent slash regeneration burn, probably account for part of this difference. However, reduced inputs of organic matter in litterfall, slower rates of surface litter breakdown and increased rates of microbial mineralization of soil organic matter on recently clearfelled areas may also contribute substantially to deplet

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00925.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractCommunity descriptions and distributions of the dominant subtidal macroalgae were recorded for the D'Entrecasteaux Channel, Tasmania. These were related to the major environmental parameters of light, water movement, substrate and depth.Six communities were recognized subjectively:(1) Durvillaea, (2) Phyllospora, (3) Macrocystis, (4) Ecklonia, (5) Fucoid and (6) Seagrass‐Cauterpa.These divisions were supported by cluster analysis of data from Tinderbox, a site at the northern end of the Channel.Detrended correspondence analysis of community data suggested that light was the principal factor (Axis 1), followed by water movement, in determining species distributions at Tinderbox.The algal communities determined are consistent with the generalized scheme proposed by Edgar (1984) for this area and are indicative of cold temperate waters and the Maugean subprovinc

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00926.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractSpecies of the hypogeous fungus genus.Mesophelliahave been shown to form ectomycorrhiza withEucalyptus diversicolorand improve seedling growth. Since the morphology of these fungi increases their dependence on animal mycophagy for spore dispersal, these results imply a tripartite interrelationship between eucalypts, hypogeous fungi and marsupials which parallels the North American interrelationship between ectomycorrhizal pine, hypogeous fungi and rodents. An understanding of the independent but analogous interrelationships on the two continents has implications for forest management, especially in regard to the effects of forest conversion on other members of the ecosystem.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00927.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractIn the subalpine tract of the Bogong High Plains (37°S, 147°E; altitude 1600–1800 m a.s.l.) the vegetation consists of a mosaic of snow gum(Eucalyptus pauciflora)woodland, heathland, grassland and wetland communities. Classification (polythetic‐agglomerative) and ordination (principal co‐ordinates analysis) of quadrat data from heathlands and grasslands on relatively well drained sites allowed the identification of four main heathland and grassland vegetation units. These units may be ranked in a structural and floristic continuum, from closed heath variously dominated byProstanthera cuneata, Orites lancifoliaandPhebalium squamulosumto closed heath dominated byP. squamulosumandGrevillea australis,open grassy heath ofG. australisandPoa hiemata.and grassland ofP. hiemata.The transition fromProstantheraclosed heath toPoagrassland is correlated with gradients of decreasing steepness and rockiness of terrain, and increasing exposure an

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00928.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractGrassy woodland, grassy shrubland, grassy sedgeland, tussock grassland and grassland are extensive on basalt, limestone and fine‐textured Quaternary deposits, are occasional on dolerite, granite and fine‐grained sedimentary rocks, but are absent from the siliceous mountains of Tasmania. With the exception of limestone lithosols, the grassy communities are confined to relatively deep soils with a low surface rock cover. Much of the area of the grassy communities below the climatic treeline has clearly been forest in the recent past, although some of the higher subalpine plains seem likely to have been grassy at least since the peak of the Last Glacial. The first axis of an ordination of floristic data from 190 quadrats had at one extreme the grassy communities which most resembled in their species composition the sedgelands and sclerophyll shrub woodlands of the west of Tasmania, and at the other extreme the grassy woodlands on relatively fertile, well drained sites in the centre and east of Tasmania. The second axis was correlated with altitude, probably inversely reflecting the growing season. The third axis was related most closely to a soil drainage index. Many of the 15 communities recognized from a polythetic divisive classification of the quadrats have highly local distributions. Six of the communities are totally unreserved and four are poorly reserved. An iterative method is used to develop a minimum reservation strategy involving seven ar

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00929.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Bioturbation, rainwash and texture contrast soils: An evaluation of transporting processes on soil genesis in the Sydney Basin G. S. HumphreysSome aspects of the role of bioturbation in soil formation in south‐eastern Australia P. B. MitchellPlant water relations and community water use in aBanksiawoodland near Perth, Western Australia Jonathan DoddThe pre‐mining assessment of a coal mining lease north of Esperance, Western Australia Paul G. van der Mo

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00930.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY