Baltimore Ecosystem Study: Riparian vegetation data - 1 of 11 - 1999 and 2004 trees

This is one of 11 datasets generated in a study of riparian vegetation
in the Baltimore Ecosystem Study from 1999-2004. Comparisons of
vegetation between the rural/suburban (upper) and urban (lower)
sections of the watershed show distinct patterns across an urban to
rural gradient. In the lower, more urban section of the watershed,
wetland tree species are either absent or occur as small stems while
upland species are abundant, in mixed sizes. A comparison of the
number of wetland and upland species in the mostly urbanized Gwynns
Falls riparian zone with non-urbanized Piedmont floodplains throughout
Maryland shows approximately twice as many upland species in the urban
floodplain than in non-urbanized floodplains. The majority of shrubs
in riparian zones through the Gwynns Falls are upland species. For
herbaceous species, frequencies of upland and wetland species are
about equal in the upper and middle regions of the watershed, but
upland species are more common in the more urban lower floodplains by
a factor of greater than two.

本数据集为1999-2004年巴尔的摩生态系统研究（Baltimore Ecosystem Study）中针对河岸植被开展的专项研究所生成的11套数据集之一。对该流域农村/郊区（上游段）与城市（下游段）的植被开展对比分析，可观测到沿城乡梯度分布的显著植被格局差异。在城市化程度更高的下游流域段，湿地乔木物种要么完全缺失，要么仅以低矮茎干的个体存在；而旱地物种则数量丰富，且植株大小混杂不均。针对城市化程度较高的格温斯福尔斯（Gwynns Falls）河岸带与马里兰州全域未城市化的皮埃蒙特（Piedmont）洪泛平原的湿地、旱地物种数量进行对比后发现，城市洪泛平原的旱地物种数量约为未城市化洪泛平原的两倍。格温斯福尔斯河岸带中的绝大多数灌木均为旱地物种。对于草本植物而言，流域上游与中游区域的旱地和湿地草本物种出现频率大致相当，但在城市化程度更高的下游洪泛平原中，旱地物种的出现频率则高出两倍以上。