Twedt Daniel J, Uihlein William B, Elliott A Blaine
USGS-Patuxent Wildlife Research Center, 2524 South Frontage Road, Suite C, Vicksburg, MS 39180, USA.
Conserv Biol. 2006 Feb;20(1):100-10. doi: 10.1111/j.1523-1739.2005.00303.x.
The historical area of bottomland hardwood forest in the Mississippi Alluvial Valley has been reduced by >75%. Agricultural production was the primary motivator for deforestation; hence, clearing deliberately targeted higher and drier sites. Remaining forests are highly fragmented and hydrologically altered, with larger forest fragments subject to greater inundation, which has negatively affected many forest bird populations. We developed a spatially explicit decision support model, based on a Partners in Flight plan for forest bird conservation, that prioritizes forest restoration to reduce forest fragmentation and increase the area of forest core (interior forest >1 km from "hostile" edge). Our primary objective was to increase the number of forest patches that harbor >2000 ha of forest core, but we also sought to increase the number and area of forest cores >5000 ha. Concurrently, we targeted restoration within local (320 km2) landscapes to achieve > or =60% forest cover Finally, we emphasized restoration of higher-elevation bottomland hardwood forests in areas where restoration would not increase forest fragmentation. Reforestation of 10% of restorable land in the Mississippi Alluvial Valley (approximately 880,000 ha) targeted at priorities established by this decision support model resulted in approximately 824,000 ha of new forest core. This is more than 32 times the amount of core forest added through reforestation of randomly located fields (approximately 25,000 ha). The total area of forest core (1.6 million ha) that resulted from targeted restoration exceeded habitat objectives identified in the Partners in Flight Bird Conservation Plan and approached the area of forest core present in the 1950s.
密西西比河冲积平原历史上的低洼硬木林面积已减少了75%以上。农业生产是森林砍伐的主要动因;因此,砍伐行为特意针对地势较高且较干燥的区域。现存森林高度破碎化,水文状况也发生了改变,较大的森林碎片遭受的洪水淹没程度更高,这对许多森林鸟类种群产生了负面影响。我们基于森林鸟类保护的“携手同行”计划,开发了一个空间明确的决策支持模型,该模型将森林恢复工作按优先顺序排列,以减少森林破碎化并增加森林核心区域(距“不利”边缘1公里以上的内部森林)的面积。我们的主要目标是增加拥有超过2000公顷森林核心区域的森林斑块数量,但我们也试图增加面积超过5000公顷的森林核心区域的数量和面积。同时,我们将局部(320平方公里)景观内的恢复工作作为目标,以实现森林覆盖率达到或超过60%。最后,我们强调在恢复工作不会增加森林破碎化的地区,恢复地势较高的低洼硬木林。按照这个决策支持模型确定的优先顺序,对密西西比河冲积平原10%的可恢复土地(约88万公顷)进行重新造林,产生了约82.4万公顷的新森林核心区域。这比通过随机选址的田地重新造林增加的核心森林面积(约2.5万公顷)多32倍以上。有针对性的恢复工作所形成的森林核心区域总面积(160万公顷)超过了“携手同行”鸟类保护计划中确定的栖息地目标,接近20世纪50年代时的森林核心区域面积。