CONSERVATION OF CHANGING LANDSCAPES: VEGETATION AND LAND‐USE HISTORY OF CAPE COD NATIONAL SEASHORE

The pervasive impact of historical land use is often underappreciated in the management and restoration of conservation areas and natural resources. We used historical and ecological approaches to determine the relative influences of past land use, fire, and site conditions on woodland vegetation patterns in Cape Cod National Seashore (CACO), the largest protected coastal landscape and area of sand-plain vegetation in New England. Coastal sand plains are the focus of intense conservation activity because they support uncommon plant and animal assemblages that are dynamic as a result of past disturbance and ongoing human impacts. CACO was predominantly wooded prior to extensive land clearance for historical ag- riculture. Historical maps and modern soil profiles indicate that by the mid-19th century, -44% of the area supporting sand-plain woodlands in CACO was plowed for crops or pasture, 42% was logged repeatedly but never cleared, and 14% was open and subjected to diverse uses. Relationships between modern vegetation and 19th-century land use are striking and largely independent of site conditions. Continuously wooded areas support pine-oak woodlands with abundant ericaceous shrubs, whereas previously plowed sites have less canopy oak, more pine, few ericaceous shrubs, and a distinct understory including the grass Deschampsia flexuosa and the shade-intolerant shrub Arctostaphylos uva-ursi. Current composition and historical sources suggest that past agriculture generated extensive heathland and grassland habitats, much of which has subsequently reforested. In contrast to many interpretations and management guidelines, the persistent influence of fire is prin- cipally on the canopy composition and structure of former woodlots. The results highlight a need (1) to integrate an understanding of past land use into ecological models underlying the management of biological reserves; and (2) to consider the use of management ap- proaches that mimic past agricultural practices in order to maintain and restore important sand-plain habitats.

在保护区和自然资源的管理与恢复中，历史土地利用的广泛影响往往未得到充分重视。我们运用历史和生态学方法，确定了过去土地利用、火灾和立地条件对科德角国家海岸（CACO）林地植被格局的相对影响。科德角国家海岸是新英格兰最大的受保护沿海景观和沙原植被区。沿海沙原是重点保护区域，因为它们拥有因过去的干扰和持续的人类影响而动态变化的珍稀动植物群落。在因历史上的农业活动而大规模开垦土地之前，CACO主要是林地。历史地图和现代土壤剖面显示，到19世纪中叶，CACO中支持沙原林地的区域约44%被开垦用于种植作物或作为牧场，42%被反复砍伐但从未开垦，14%是空地并用于多种用途。现代植被与19世纪土地利用之间的关系显著，且在很大程度上与立地条件无关。一直有树木的区域生长着有大量石南属灌木的松栎林，而以前开垦过的地方橡树树冠较少，松树较多，石南属灌木很少，并且下层植被独特，包括曲芒发草和不耐阴的熊果灌木。当前的植被组成和历史资料表明，过去的农业活动造就了大片的石南灌丛和草地栖息地，其中大部分后来又重新造林。与许多解释和管理指南不同的是，火灾的持续影响主要体现在以前林地的树冠组成和结构上。研究结果强调了两点需求：（1）将对过去土地利用的了解纳入生物保护区管理所依据的生态模型中；（2）考虑采用模仿过去农业实践的管理方法，以维护和恢复重要的沙原栖息地。