VALUING PLANTS IN NATURAL AREAS

The introduction and spread of non-native plant species is currently a management concern in many natural areas of the United States. Beyond the assumptions that native plants are superior to non-natives or that natives may be competitively displaced, few people have attempted to understand hidden factors that define this type of biological invasion as problematic. One such hidden factor is the discrete time frame associated with European settlement of the New World. Presettlement plant communities, presumably comprising all native plant species, provided a baseline for ecologists to judge or value human-directed change in these communities (i.e., the presettlement state of vegetation took on historical significance). In this context, biological invasion is viewed negatively because it is linked to human activity and because it may change the composition of existing plant communities. The human enterprise of natural area protection establishes situations where biological invasion is unavoidable. Thus, new attitudes toward non-native plants need to be developed or altered, or emerging ecological processes associated with invasion need to be understood, and anthropic systems with high numbers of non-native plants need to be considered for natural area designation.