摘要:

AbstractPopulation differences in growth rate, drought resistance, and aspects of tissue water relations in seedlings of two neighbouring populations of E. viminalis on basalt and granite soils have been reported previously (Ladiges 1974a, b). The present work has confirmed these differences and field studies have related them to differences in edaphic factors.The granite soil supports the slower growing, more drought‐resistant population. Moisture contents for this soil were lower over a twelve‐month period than for the basalt soil. Estimated pF values for granitic top‐soil were higher and above 5 for six months of the year. During the drier months, leaf water potentials of mature trees on the granite were lower than for trees on the basalt and reached average values of ‐28 bars in March 1974.A comparison of open‐pollinated seedlings on two areas of granite, 0–4 km and 2–0 km from the trees on the basalt, suggested that there is a degree of gene flow between trees on the basalt and trees on the nearer granite site. The results therefore suggest some outcrossing in E. viminalis. Prior to 1900, stands on the basalt area were probably continuous with those on the more distant granite site and a degree of gene flow would have occurred.It appears that differential selection pressures have been primarily responsible for the population differences noted in growth rate and droug

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1976.tb01093.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe effect of mild fires on the soil fauna was examined in a Pinus pinaster plantation and in Jarrah (Eucalyptus marginata) and Karri (E. diversicolor) forests. In the pine plantation, litter decomposition ceases until four years after burning. In both native forests, species diversity and density are reduced after burning and do not recover their pre‐burning values during a normal prescribed burning rotation. Prescribed burning on a five to seven year rotation is likely to permanently simplify the litter fauna and flora, with far‐reaching effects on forest and hygi

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1976.tb01094.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractLitter decomposition rates and the population densities of soil microarthropods were measured in three Pinus pinaster stands thirty‐one, twenty‐three and eighteen years old, and on an area of native vegetation on sandy soil at Gnangara, W.A. Litter decomposition was faster in the soil than within the litter layer and was slowest at the litter surface. Decomposition was rapid in cool wet seasons and slow in hot, dry summers. Microarthropod population densities were similar on all sites (77–100 × 103/m2) but species diversity was greatest under native vegetation and least under the youngest pine stand. The impoverished soil micro‐fauna of the pine stands is unable to decompose pine or sclerophyll litter as fast as the full complement of soil microfauna in native ve

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1976.tb01095.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractTwo sampling methods for aphids are described. The first is a photographic method that allows sampling with replacement for use in field experiments and in which a linear regression technique is used to estimate the errors of sampling. The second method is a ranking procedure for sampling natural populations in which regressions of aphid numbers on ‘colony length’ are used to minimize b

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1976.tb01096.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractIsoneurothrips australis Bagnall lives in the flowers o, Eucalyptus trees. Knowing the mean number of thrips per flower, an estimate of the number of flowers was required so that the number of thrips in an isolated patch of scrub could be calculated. Flowers were sampled by two methods and the results compared and combined. The propriety of using probabilities higher than 0.05 for the calculation of confidence limits is discussed.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1976.tb01097.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe conflicting but informative literature relating to goats on Lord Howe Island (31° 35’5 159° 05’ E) is reviewed. Observations made in 1970–72 indicate that the effects of goats are localized. Invasion of goat camps by naturalized plants is widespread. Changes attributable to goats are considered and one well documented example is discussed in detail. The effects of goats and pigs are compared. Goats occupy different but overlapping habitats from pigs. A total of 228 goats was shot in an extermination programme. Overall density is 0·17 goats/ha but local densities may vary from 0·56 goats/ha to 26·34 goats/ha. Rumen content analyses indicate that goats are both selective and individualistic feeders. Naturalized plants are eaten in the same proportion as they occur in the flora. The relationship between naturalized weeds and goats appears to be

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1976.tb01098.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Book review in this articleMultivariate Analysis in Vegetation Research L. Orloci

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1976.tb01099.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Long‐term change in arid zone vegetation at Koonamore, South Australia M. D. CrispCatchment water balance studies on the wet tropical coast of North Queensland D. A. GilmourAssessment of arid‐zone vegetation using airphoto pattern Silvia E. B.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1976.tb01100.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY