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Showing papers on "Undergrowth published in 1983"


Journal ArticleDOI
01 Dec 1983-Ecology
TL;DR: The variety of activity patterns exhibited by birds on moisture and vegetation gradients clearly demonstrates the complexity of dynamics that affect assemblage attributes and undermines the recent perception of a dichotomy between equilibrium (deterministic) and nonequilibrium (stochastic) assemblages.
Abstract: Both physical and biological processes shape species assemblages (communities) For birds, vegetation structure has long been assumed to be the dominant factor in habitat selection, especially along successional gradients While vegetation may be important as a proximate factor, detailed knowledge of ultimate factors governing habitat selection is required Gradients of microcli- mate, especially temperature and moisture, may be such an ultimate factor through direct physiolog- ical pressures on birds or indirectly through distribution and availability of food resources We doc- umented the existence of gradients of both vegetation structure and microclimate in the undergrowth of seasonally humid forest in central Panama To assess the relative importance of these gradients in shaping local avian distribution, birds were netted in undergrowth (up to 3 m above ground) during 2-wk periods in dry (March) and wet (July) season for 4 yr (1979-1982) A total of 3037 captures of 95 species was recorded during that period Although patterns of species richness and capture rate are relatively simple, species composition and other assemblage attributes are complex and difficult to interpret without careful evaluation of the dynamics of individual species The variety of activity patterns exhibited by birds on moisture and vegetation gradients clearly demonstrates the complexity of dynamics that affect assemblage attributes Overall, birds are more active at dry sites and at sites with intermediate shrub density However, activity levels change with time, suggesting that avian activity reflects a dynamic process of habitat selection Though no food resource data are available at present, the general pattern of habitat use on diurnal time scales for several guilds suggests that birds track microclimatic optima for physiological reasons Habitat selection processes are both ex- tremely complex and variable in time and space for the avifauna of tropical forest undergrowth Indeed, the scale of study in space and time is important in determining the conclusion of a study The recent perception of a dichotomy between equilibrium (deterministic) and nonequilibrium (stochastic) assemblages is undermined by these results Habitat selection in birds produces dynamic (nonequilibrium) assemblages in space and time However, these are not stochastic assemblages Each species seeks habitat optima in the context of current environmental conditions on diurnal, seasonal, and between-year time scales Thus, instead of nonequilibrium and stochastic assemblages, the avifaunas of tropical forest undergrowth are nonequilibrium but relatively predictable from knowl- edge of current environmental conditions

228 citations


Journal ArticleDOI
TL;DR: It was made clear by germination and growth tests that pine toxic substances inhibit the germination of low frequency species more than high frequency species in a red pine forest and that these substances are contained in descending concentration in fresh and fallen leaves, roots, pine forest soil, and pine rain.
Abstract: Correlation between the distributional frequency of undergrowth species of red pine forest and their germination and growth effected by pine extracts and leachates was found. It was made clear by germination and growth tests that pine toxic substances inhibit the germination and growth of low frequency species more than high frequency species in a red pine forest and that these substances are contained in descending concentration in fresh and fallen leaves, roots, pine forest soil, and pine rain. The concentration of pine toxic substances in extracts or leachates was affected by extracting or leaching within a given period of time, requiring a few hours for extracts or a few days for leachates. The amount of dry weight inhibition of the undergrowth treated by pine leachates was expressed as a growth inhibition index (GII) for the comparison of tolerance in various species. GII is a relative value (%) of the test groups against the control and it is an exponential function of the amount of pine toxic substances affecting the dry weight of the undergrowth. The substances were analyzed by paper and gas chromatography. Benzoic acid and 11 phenolic acids were identifed by gas chromatography. Benzoic acid was considered to be a key factor of allelopathy in the red pine forest.

50 citations



Journal ArticleDOI
TL;DR: Hylophylax naevia of moderately dense forest undergrowth and H. punctulata of open swamp undergrowth tend to sally for arthropods in low foliage rather than sally to the ground among large ant-following antbirds.
Abstract: Hylophylax naevia of moderately dense forest undergrowth and H. punctulata of open swamp undergrowth tend to sally for arthropods in low foliage rather than sally to the ground among large ant-following antbirds. They and related Hypocnemoides melanopogon of swamp understory edges are also limited by their microhabitat niches in following ants. Myrmoderus ferrugineus and M. loricatus, ground-walking small antbirds seemingly derived from Hylophylax, follow ants infrequently, probably because ants, large ant-following birds, and predators would attack them if they did so.

6 citations


Journal ArticleDOI
TL;DR: Compared to those obtained during simultaneous studies on the resting site preferences of G. p.
Abstract: A study of the resting site preferences of Glossina palpalis gambiensis in an area of a gallery forest in the Northern Guinea Savanna of Mali, infested exclusively by G. p. gambiensis was conducted in February, 1980 (hot dry season). Five site-types were compared: fallen logs, boles, undergrowth, tree canopies and branches. Distribution of resting flies was as follows: fallen logs (55.62%), boles (35.24%), undergrowth (8.4%), tree canopies (0.61%) and branches (0.00%). Most of the flies were collected during the periods 06.00–09.00 (37.47%) and 09.00–12.00 hr (46.5%). On boles, 86.06% of flies were found below 1.0 m and no flies were collected above 2.0 m. These results are compared to those obtained during simultaneous studies on the resting site preferences of G. p. gambiensis in an area along the same gallery forest, with mixed G. p. gambiensis and G. morsitans submorsitans infestation. Possible reasons for the differences observed are discussed.

2 citations