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321.
Min B. Rayamajhi Thai K. Van Paul D. Pratt Ted D. Center 《Wetlands Ecology and Management》2006,14(4):303-316
Melaleuca quinquenervia dominates large areas of the Florida Everglades in the southeastern USA where it has transformed sedge-dominated marshes
into melaleuca forests. Despite its prevalence, very little is known about the ecology and stand dynamics of this invasive
tree. We delineated large-, intermediate-, and small-tree stands in non-flooded, seasonally flooded and permanently flooded
areas of Florida in 1997, measured their biological attributes, and then quantified litterfall components for 3–4 year periods.
Melaleuca wood components and mature seed-capsules comprised the largest and the smallest portions of aboveground biomass,
respectively, while leaves, fine stems, mature fruits, bud scales, floral structures, and residues represented decreasingly
smaller fractions of the litter during the succeeding year. Dry weight proportion of leaves in litter was greatest (80.9%)
in non-flooded and least (69.1%) in permanently flooded habitats. It was also greatest in small (85.6%) and least in large
(64.7%) tree stands. Reproductive structures and mature-fruit fractions in litter were highest in large-tree stands whereas
the bud-scale fraction showed no relationship to tree size. Seasonally flooded habitats had the most litterfall, wherein small-,
intermediate-, and large-tree stands generated 0.662, 0.882, and 1.128 kg m−2 yr−1, respectively. Dry weight of stems, leaves, bud–scales, floral structures, and mature fruit fractions in litter increased
as the predominant size of the trees in the stand increased. Total annual litter production was highest during 1999–2000.
Leaf fall occurred year-round with maximal amount during April, July, and October. Highest amounts of bud scales and floral
structures fell during October–January, which corresponded with flushes of vegetative growth and major flowering events. Overall,
melaleuca alone accounted for nearly 99% of the total litterfall dry weight in all habitats and months sampled. The amount
of non-melaleuca litter was greater in small-tree stands than in intermediate- or large-tree stands. Litterfall data of this
nature will be helpful in detecting changes occurring in melaleuca canopies in response to biological control impact and in
prescribing site-specific management strategies. 相似文献
322.
323.
The human gene for aromatic L-amino acid decarboxylase (DDC) was previously assigned to chromosome 7 by analysis of a panel of somatic cell hybrids. We report here refinement of this localisation, by in situ hybridisation, to 7p13-->p11. 相似文献