Presettlement Vegetation of Two Prairie Peninsula Counties
Presettlement Vegetation of Two Prairie Peninsula Counties
复制标题
草原半岛两县预安置植被
作者：
C. Rodgers;R. C. Anderson
根据原始的土地普查记录（1821- 1824），伊利诺伊州麦克莱恩和梅森县的预定居植被包括四种植被类型（草原、稀树草原、开放森林和封闭森林），根据树木密度进行区分。利用四分之一法对调查记录中的信息进行改进，估计了各植被类型中树木分类群的密度、优势度、频率和重要性值。麦克莱恩县的预定居植被以草原为主（89.5%）。以白栎（Quercus alba）为主的稀树草原、开阔林和闭林分别占总植被的5.4%、1.8%和3.3%。今天，该县约有0.9%的土地仍被森林覆盖。Mason县的预定居植被为67.7%的草原、14.4%的稀树草原、4.3%的开放森林和9.0%的封闭森林。湖泊和沼泽占全县面积的4.6%。预定居林以黑栎（Q. velutina）为主。目前，该县约有2%的面积是森林。在这两个县，森林地区都出现在与溪流、河流、冰川冰碛和沙丘相关的崎岖地形上。植被类型与土壤关联关系显著相关。一般来说，在预定居时期，森林土壤与草原土壤不同。
Based on the original General Land Survey records (1821-24), the presettlement vegetation of McLean and Mason Counties, Illinois, included four vegetation types (prairie, savannah, open forest, and closed forest), separated on the basis of tree density. Density, dominance, frequency, and Importance Values were estimated for tree taxa in each vegetation type by applying a modification of the quarter method to the information in the survey records. The presettlement vegetation of McLean County was mostly prairie (89.5%). Savannah, open forest, and closed forest, dominated by white oak (Quercus alba), comprised 5.4%, 1.8%, and 3.3%, respectively, of the total vegetation. About 0.9% of the county is still forested today. The presettlement vegetation of Mason County consisted of 67.7% prairie, 14.4% savannah, 4.3% open forest, and 9.0% closed forest. Lakes and swamps covered 4.6% of the county. Presettlement forests were dominated by black oak (Q. velutina). Presently, about 2% of the county is forested. In both counties, forested areas occurred on rugged topography associated with streams, rivers, glacial moraines, and sand dunes. Significant associations were found between vegetation types and soil associations. Generally, the soils in the forests differed from those in the prairies in presettlement times.