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231.
CATHRYN H. GREENBERG AIMEE LIVINGS TOMCHO J. DREW LANHAM THOMAS A. WALDROP JOSEPH TOMCHO ROSS J. PHILLIPS DEAN SIMON 《The Journal of wildlife management》2007,71(6):1906-1916
Abstract: We compared the effects of 3 fuel reduction techniques and a control on breeding birds during 2001-2005 using 50-m point counts. Four experimental units, each >14 ha, were contained within each of 3 replicate blocks at the Green River Game Land, Polk County, North Carolina, USA. Treatments were 1) prescribed burn, 2) mechanical understory reduction (chainsaw-felling of shrubs and small trees), 3) mechanical + burn, and 4) controls. We conducted mechanical treatments in winter 2001-2002 and prescribed burns in spring 2003. Tall shrub cover was substantially reduced in all treatments compared to controls. Tree mortality and canopy openness was highest in the mechanical + burn treatment after burning, likely due to higher fuel loading and hotter burns; tree mortality increased with time. Many bird species did not detectably decrease or increase in response to treatments. Species richness, total bird density, and some species, including indigo buntings (Passerina cyanea) and eastern bluebirds (Sialia sialis), increased in the mechanical + burn treatment after a 1-year to 2-year delay; eastern woodpewees (Contopus virens) increased immediately after treatment. Hooded warblers (Wilsonia citrina), black-and-white warblers (Mniotilta varia), and worm-eating warblers (Helmitheros vermivorus) declined temporarily in some or all treatments, likely in response to understory and (or) leaf litter depth reductions. Densities of most species affected by treatments varied with shrub cover, tree or snag density, or leaf litter depth. High snag availability, open conditions, and a higher density of flying insects in the mechanical + burn treatment likely contributed to increased bird density and species richness. In our study, fuel reduction treatments that left the canopy intact, such as low-intensity prescribed fire or mechanical understory removal, had few detectable effects on breeding birds compared to the mechanical + burn treatment. High-intensity burning with heavy tree-kill, as occurred in our mechanical + burn treatment, can be used as a management tool to increase densities of birds associated with open habitat while retaining many forest and generalist species, but may have short-term adverse effects on some species that are associated with the ground- or shrub-strata for nesting and foraging. 相似文献
232.
CATHRYN H. GREENBERG DOUGLAS J. LEVEY DAVID L. LOFTIS 《The Journal of wildlife management》2007,71(2):321-335
ABSTRACT Fleshy fruit is a key food resource for both game and nongame wildlife, and it may be especially important for migratory birds during fall and for resident birds and mammals during winter. Land managers need to know how land uses affect the quantities and species of fruit produced in different forest types and how fruit production varies seasonally and as young stands mature. During June 1999-April 2004, we quantified fleshy fruit abundance monthly in 31 0.1-ha plots in 2 silvicultural treatments: 1) young 2-age stands with low basal area retention, created by shelterwood-with-reserves regeneration cuts (R; harvested 1998–1999); and 2) uncut mature closed-canopy stands (M) in 2 common southern Appalachian, USA, forest types (upland hardwood and cove hardwood [CH] forests). Over the 5-year study period, total dry pulp biomass production was low and relatively constant in both M forest types (x̄ = 0.5-2.0 kg/ha). In contrast, fruit production increased each year in R, and it was 5.0 to 19.6 times greater in R than in M stands beginning 3–5 years postharvest. Two disturbance-associated species, pokeweed (Phytolacca americana) and blackberry (Rubus allegheniensis), produced a large proportion of fruit in R but showed different patterns of establishment and decline. Huckleberry (Gaylussacia ursina) recovered rapidly after harvest and was a major producer in both silvicultural treatments and forest types each year. Several herbaceous species that are not associated with disturbance produced more fruit in CHR. Few species produced more fruit in M than in R. Fruit production by most tree species was similar between R and M, due to fruiting by stump sprouts in R within 1–3 years postharvest. Fruit availability was highest during summer and early fall. American holly (Ilex opaca), sumac (Rhus spp.), and greenbriar (Smilax spp.) retained fruit during winter months but were patchy in distribution. In the southern Appalachians, young recently regenerated stands provide abundant fruit compared to mature forest stands and represent an important source of food for wildlife for several years after harvest. Fruit availability differs temporally and spatially because of differences in species composition, fruiting phenology, and the dynamic process of colonization and recovery in recently harvested stands. Land managers could enhance fruit availability for many game and nongame species by creating or maintaining young stands within forests. 相似文献