Showing papers on "Undergrowth published in 1988"

Forest Communities and Patterns

Abstract: The vegetation of the Coweeta Basin is traditionally included in the oak-chestnut association (Braun 1972). However, since chestnut (Castanea dentata) has been lost as a dominant due to the chestnut blight, the area is probably more correctly classified as belonging to the oak-hickory association. The plant communities in the basin are typically diverse for the southern Appalachians and are distributed in a reasonably predictable mosaic over the highly varied topography in relation to moisture gradients (Day and Monk 1974). The composition and structure of many of these communities are apparently still changing and are dynamic. The predominant species composition is a mix of deciduous oaks with a commonly abundant evergreen undergrowth of Rhododendron maximum and mountain laurel (Kalmia latifolia). (Species authority throughout this paper follows Radford et al. (1964).)

Birds Lost from a Giant Sequoia Forest during Fifty Years

Abstract: Not all forest bird species breeding on Redwood Mountain, Tulare County, California in the 1930s are still there in the 1980s. Over the 50 Years virgin aiant seauoia forest of the saddle and east slope (within Rings Canyon NationalPark) remains unchanged but has lost the Olive-sided Flycatcher (Contopus borealis). The mixture of old and secondgrowth sequoias of Whitaker’s Forest, where pines and undergrowth were removed and snags eliminated, is missing the Mountain Quail (Oreortyx pictus), Flammulated Owl (Otus flammeolus), Northern Pygmy-Owl (Glaucidium gnoma), Spotted Owl (Strix occidentalis), Hairv Woodnecker (Picoides villosus). and Olive-sided Flvcatcher. Thouah unchanaed todav. the Xparian alders of Eshom Creek on the west slope have lost Swainso& Thrush~Catha& ustulatus). Drastic logging by Sequoia National Forest has driven all of the above from the west slope ponderosa pine forest that surrounds Whitaker’s Forest. New birds established at Whitaker’s Forest by 1986 are the Common Raven (Corvus corax), House Wren (Troglodytes aedon), and Lincoln’s Sparrow (Melospiza lincolnii). Intrusion of Brown-headed Cowbirds (Molothrus ater) has begun without yet affecting two abundant species of vireos. The Pileated Woodpecker (Dryocopus pileatus) is reduced; the Winter Wren (Troglodytes troglodytes) has greatly increased. I attempt to explain avifaunal changes by comparing habitats over the 50-year interval. Disappearance of the flycatcher and thrush from unchanged, prime habitat must be caused by destruction of corresponding forests in Central America, where these birds maintain their winter territories.

Allelopathic exclusion of understorey by a few multi-purpose trees

Abstract: SUMMARY The floristic composition and biomass of the understorey was assessed in three 4-year old multi-purpose tree species. Compared to 29 species in the open, Leucaena leucocephala harboured only 5, Eucalyptus tereticornis 12, and Casuarina equisetifolia 18. The dry weight of the ground cover was also considerably restrained under the trees and the proportional reduction was comparatively less in C. equisetifolia. Suppression of ground vegetation is ascribed to allelopathic affects rather than to physical competition for light, water and nutrients. Of the three tree species, C. equisetifolia proved less injurious to the undergrowth. In contrast to the other trees the dominant species under L. leucocephala was L. leucocephala itself, indicating its lack of autotoxicity.