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Vegetation patterns and processes of natural regeneration in periodically flooded riparian forests in the Central Valley of California.

I-Yun Mandy. Tu University of California, Davis. 2000

Dissertation Abstracts International 61-12B.

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題名:
Vegetation patterns and processes of natural regeneration in periodically flooded riparian forests in the Central Valley of California.
著者: I-Yun Mandy. Tu
University of California, Davis.
主題: Biology, Botany; Biology, Ecology
所屬期刊: Dissertation Abstracts International 61-12B.
描述: Riparian forests in California Central Valley bottomlands are typically highly disturbed habitats that have been altered by changes in hydrology, land-use practices, and exotic species invasion. Today, only small, disjunct patches of pristine, mature forest remain. This study identified several forests along the Cosumnes River (the only undammed river remaining in California's Central Valley) to be used as reference sites of undisturbed healthy forests. The vegetation composition and spatial structure, as well as regeneration of native woody species were examined. Changes in community composition over time, in both the standing vegetation and in the seed bank, were also investigated.
From these forests, three plant associations were described using the Braun-Blanquet classification procedure. These associations represent different stages of forest development, and were characterized by species composition, physiognomy, and age. Multivariate analyses determined that stand elevation alone, at this particular scale, was not an adequate predictor of community composition. Rather, soil substrate composition was critical in determining species distributions. Total species diversity increased with forest age. Further, native plant species diversity was more allied with total species diversity over time, as the ratio of native to exotic species also increased.
An evaluation of regeneration rates of native woody species showed that natural inputs of seeds and vegetative growth are adequate to sustain the current composition and structure of these forests. In the earliest stage of forest development, input from branch fragments of Populus fremontii and Salix spp. onto a newly created sandbar was shown to be six times more important than recruitment from seeds. In older forests with a closed canopy, seedlings of Fraxinus latifolia, Acer negundo, and Quercus lobata survived at rates which suggest that current mature tree densities will be sustained. Additionally, the role of the soil seed bank in forest regeneration was determined to be vital, especially for herbaceous species. Over successional time, however, the role of the permanent (vs. transient) soil seed bank becomes less important in forest regeneration dynamics, as native perennial species, which typically rely on vegetative propagation, become dominant.
出版者: Thesis (Ph.D.)--University of California, Davis, 2000.
建立日期: 2000
格式: 181 p..
語言: 英文
識別號: ISBN0493056041
資源來源: NUTN ALEPH

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Vegetation patterns and processes of natural regeneration in periodically flooded riparian forests in the Central Valley of California.

I-Yun Mandy. Tu University of California, Davis. 2000

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