Showing papers on "Undergrowth published in 1980"

Demography of an undergrowth palm in littoral Cameroon.

Abstract: This study of Podococcus barteri in Cameroon, equatorial West Africa, shows that the longevity of this small palm is in the range of 63-74 years. Seasonality is more pronounced in flowering than in leaf production. Adults produce one leaf per year, each lasting about five years in the crown. Proliferation by stolons begins many years before flowering. The leafy stolons may grow two-eight or more years before establishing the ramets. Inflorescence development, flowering, and seed maturation take about 1.4 years. Only 0.08 percent of the ovules become mature seeds. A stage projection matrix gives the annual population growth rate as 1.2 percent. The growth index X is more sensitive to changes in mortality of juveniles and young adults than of seeds-seedlings, mature-old adults, or stolons. Mortality at several stages of sexual reproduction and the size advantage of ramets account for the greater importance of cloning to population dynamics, although the relative energetics have not been assessed. IN LOWLAND WET FORESTS, the occasional disruption of the deep-shade and sunfleck environment by falling trees results in luxuriant growth of many species. Tree-fall gaps have been considered the main organizing feature of population and community dynamics (Aubreville 1938, Jones 1956, Whitmore 1975, Hartshorn 1978). The pattern of spatial and size distributions of many species reflects the focus of their establishment and/or maturation in gaps, but other species do not conform (e.g., Richards and Williamson 1975). The comparatively sparse plant cover of the long-enduring, abysmal gloom of the floor of mature forest has been largely ignored even in vegetation studies, and the growth and reproductive behavior of this flora is virtually unknown despite its accessibility. Palms are a particularly abundant part of this lower stratum, and convenient to study as their geometric simplicity much facilitates observation and analysis of their behavior. Even for relatively longlived species, demographic projections can be made from short-term observations (Hnatiuk 1977, Van Valen 1975 based largely on Bannister 1970). In contrast to the diversity of small palms in Malayan and American forests (Whitmore 1973, Moore 1973a), there are only two species in mature forest undergrowth in Africa. Podococcus barteri is occasionally common in the littoral region of Cameroon, growing in clusters often of 10-4 or 10-3 ha, with stem densities up to seven per m2. The habit, distribution, growth, and reproduction of Podococcus will be described here, with the purpose of assessing seasonality, the time scales relevant to individual life history, the stability of the population (of plant modules, not genets), and its sensitivity to disturbance of existing growth, reproduction, and mortality schedules. Demographic treatment of long-lived woody plants lags far behind that of herbs (Harper 1977), and is of particular interest for Podococcus as a species of the mature phase of lowland forest, and one which both clones and produces seed.

Dry-matter production of two species of bamboo (chusquea culeou and c. tenuiflora) in south-central chile

Abstract: SUMMARY (1) In south-central Chile, bamboos of the genus Chusquea often dominate the undergrowth of the mainly broad-leaved rain forests, and where these forests have been burned or logged they frequently form dense thickets in which tree regeneration is greatly impeded. (2) Standing crop and above-ground net primary production were estimated for a pure stand of C. culeou at 700 m altitude, and standing crop for C. tenuiflora in the understorey of a mixed Nothofagus betuloides-N. pumilio forest near the timberline at 1040 m in the Andes. (3) Above-ground biomass of the Chusquea culeou thicket and the C. tenuiflora undergrowth was approximately 156-162 t ha- 1 and 13.0 t ha- 1, respectively. (4) The annual above-ground net primary production for the C. culeou thicket was approximately 10.0-1 1.4 t ha- 1.

Distribution of Feeding Activity of the Eastern Grey Kangaroo, Macropus Giganteus, in Coastal Lowland of South-East Queensland.

Abstract: In an area of coastal lowland managed by the Forestry Department of Queensland, habitats differed in the density, height and species composition of their undergrowth. In natural habitats Themeda australis made up the bulk of the diet of M. giganteus, but in firebreaks a range of grasses was eaten. Kangaroos actively fed only in habitats with open undergrowth, and in these habitats the density of faecal pellets correlated with the abundance of food present. Dense undergrowth restricted use of habitat even for movement. The abundance of food and the height and density of the undergrowth in contiguous habitat influenced the abundance of sightings on firebreaks. Firebreaks create a new source of abundant food. Prescribed burning attracts kangaroos to habitats by opening up dense undergrowth and encouraging the growth of grass.