ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01294.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe vegetation associated with sandy alkaline pans and surrounding acidic peats in south‐west Tasmania is described. The upper margins of the pans are characterized by sharp environmental discontinuities, with pH changes of more than 3 units in only 20 cm being recorded. Classification and ordination of quadrats by plant species associated with a typical pan showed that five distinct communities are evident, but that these form a gradational series which reflects the altering edaphic status of the sites during infilling of the pans. The pH, drainage and redox characteristics of the substrates are among the factors determining the frequency of particular species at any stage of the progression. Frequency histograms for plant species in and around the pans indicate that many of the species respond individually to changing p

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01295.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractArthropods found associated with field populations of the Western Australian red‐ink sundew, Drosera erythrorhiza,were evaluated for their trophic relationship to the plant in a bushland site of the Spearwood Dunes System near Perth. The major prey ofDroseraleaves was the collembolan, Hypogastrura vernalis,whose presence in the Perth metropolitan area is a new record for Australia. Additional arthropods found associated withDroseraincluded primary consumers and opportunistic predators that scavenge captured prey items.Physical models ofDroseraleaves were placed in the field and used to estimate potential leaf capture rate immediately prior toDroserasenescence. These data were coupled with nitrogen (N), phosphorus (P), and potassium (K) analysis of soil, Droseracomponents and insect prey to determine thatH. vernalispopulations in the study area were sufficient to supply 100% of the observed sundew N and P pool, but a negligible proportion of the K pool. Soil sources of K exceeded any potential contribution of insect

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01296.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractPrevious studies of the ecology and regeneration strategies ofAraucaria cunninghamiiandA. hunsteiniiin New Guinea rainforests have treated these species as ecologically identical and disagree concerning their ability to maintain a stable population size in forest communities dominated by angiosperms. Vegetation data from a number of 0.5 ha forest sites in New Guinea are analysed in order to characterize forest types and their environmental regimes in the altitudinal zone from 700 to 1500 m a.s.l. Particular attention is paid to forests containing Araucaria species. Nodal component analysis identifies a number of distinct forest types or ‘series’, each dominated by a different species. Continuity analysis displays the location of sites and species in non‐linear ordination space.Subsequent regression of environmental data on the position of sites in ordination space shows that forest types are separated along gradients related to altitude and rainfall on the one hand, and soil nutrient concentrations on the other.A. cunninghamiiis generally found in wetter and less nutrient‐rich sites thanA. hunsteinii.The analysis of species presence data, as opposed to quantitative data, shows that whilst forest types are easily differentiated according to their dominant species, changes in floristic composition are subtle along the altitudinal and other gradients rec

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01297.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractConventional pattern analysis and segregation analysis were used to investigate the hypothesis that young and mature individuals ofAraucaria hunsteiniiwere not usually found growing in close association whilst the distribution of young and mature individuals ofA. cunninghamiiwas essentially random. It was considered that this pattern reflected a difference in regeneration strategy between the two species, A. hunsteiniibeing a gap regenerator andA. cunninghamiia shade‐tolerant species. A seedling growth‐experiment using three different shade treatments and four temperature treatments tested this hypothesis further. Results show thatA. hunsteiniiis more dependent on high light intensity thanA. cunninghamiifor the production of biomass.A. cunninghamiiproduces more biomass thanA. hunsteiniiunder all treatment conditi

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01298.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractAnnual litter fall, nutrient concentrations in litter components and annual weight of nutrients in litter fall have been estimated for karri forest stands aged 2, 6, 9 and 40 years and in mature forest. The weight of litter falling annually increases with stand age, ranging from 1.13 t/ha in 2‐year‐otd regeneration to 9.45 t/ha in mature forest. This increase is due mainly to greater amounts of twigs, bark and fruit falling in older stands. Leaf fait is relatively independent of stand age once the canopy of regenerating stands closes and the understorey has developed.Concentrations of N, P, K, S and Mn in karri leaf litter differ significantly between sites and the differences appear to be related to stand age. Highest levels of these elements are found in karri leaf litter from the youngest stand and the concentrations decrease with increasing stand age. The amounts of annual litter fall and of nutrients cycling in litter are among the largest reported for Australian forests. In particular cycling of Ca, K and Mg in mature karri forest is greater than has been reported for any other eucalypt forest. Karri forest understorey plays a key rote in nutrient cycling in these ecosystems, contributing 30–70% of the weight of many of the nutrients in the leaf component of titter. Understorey leaf material is particularly important in the cycling of N, S and the micro‐nutrients Cu

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01299.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe influence of animals on patterns of seed dispersal has not been well explored, despite the importance of seed dispersal in plant population biology. Furthermore, the exploitation of animals as dispersal agents has been considered one reason for the replacement of gymnosperms by angiosperms in the Cretaceous. We studied seed dispersal in a cycad, Macrozamia riedlei,and showed that in the absence of animals, ripe seeds drop directly beneath the parent not more than 40 cm from the base. Several animals eat the fleshy outer integument of the seeds, and possums(Trichosurus vulpecula),transport seeds up to 24 m from the parent. The postdispersal positioning of seeds gave a log density‐log distance relationship ofy = 7.20 – 2.85x (r2= 0.96, N = 17).Effective local dispersal may have contributed to the persistence of cycads in the world flora for the last 200 million ye

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01300.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe distribution of cattle and red kangaroos among the major communities of a 170 km2paddock in central Australia was determined from 108 and 82 air surveys respectively over a four and a half year period. Fifty‐nine surveys of each species were used in this report. Changes in use of the communities by the two species were analysed in relation to forage conditions using linear regression techniques. The two species showed trends in time of use of the open and wooded communities. Kangaroos used the mulga‐perennial community (grovedAcaciawoodland with a shrub and perennial grass understorey) during good forage conditions and moved to the drought refuge open communities when forage conditions deteriorated. Cattle, on the other hand, used the open communities during good forage conditions and tended to move to the mulga communities and the hills when drought began. Mulga‐annual (ungrovedAcaciawoodland with short grass and forb understorey) was the only major community which showed no clear linear relationship between kangaroo use and forage conditions. This might be a buffer area from which kangaroos come and go as other areas become more attractive as feeding areas. Cattle, however, show some preference for mulga annual during medium forage conditions. There appears to be little spatial interaction by the two species except during drought when kangaroos concentrate on the open communities and some cattle continue to feed in these communities. Community selection seems to be determined mainly by forage conditions, as there is no evidence that one species attracts or repels the other in spatial terms. In the conditions observed, the two species successfully coexisted with some control of numbers of cattle b

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01301.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA new method of species (inverse) classification of vegetation data, i.e. classification of species into groups with similar ecological tolerances, is presented which overcomes the problems of species abundance distorting the results. The algorithm TWO‐STEP is based on the use of an asymmetric measure of dissimilarity:wherei, jare species,his the stand,nis the total number of stands, and xihis the amount of speciesiin standh.The algorithm uses the rows of the asymmetric dissimilarity matrix generated as above to form a second symmetric dissimilarity matrix using the measure:wheremis the number of species andkthe species.Flexible sorting is applied to generate a species classification. Comparison of results after applying the TWO‐STEP algorithm and a standard alternative to an artificial data set demonstrates its efficacy. TWO‐STEP also shows considerable advantages over previous analyses for a Queensland rainforest data set (quantitative) and an English heath (qualitative) data set. Normalization of species data appears advantageous for quantitative data

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01302.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA new model for population growth as a branching process is described. It requires knowledge of the population's age‐specific survivorship and fecundity curves. The total population size at any time is calculated by summing across all branches of the tree representing the population's lineage and thus the model also allows the lineage of the developing population to be traced. Use of the model is demonstrated by a hypothetical example. The model could be of particular value in tracing the phylogenetic development of populations and/or specie

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1982.tb01303.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY