The U.S. National Vegetation Classification (NVC) employs an eight-level hierarchy, which integrates the basic aspects of vegetation (species composition, structure, environmental correlation, and geographic distribution), through a standardized set of rules of nomenclature. The descriptive units are defined quantitatively through analysis of field samples and these samples can be compared to existing data sets using vegetation data archives such as VegBank to determine their relationships. Creators of the NVC assume that vegetation defining novel ecosystems can be determined using knowledge of distributional origin of component species and by comparing vegetation aspects at a given time and place. Divergence from known conditions could be described through the presence of non-native species within the structural aspects of vegetation stands and how those novel indicators have affected change in natural processes or how anthropogenic influences on vegetation have brought upon these changes. The NVC uses the term “ruderal” to define vegetation that is driven by high frequency processes such as fire, mechanical clearing, or flooding. Fine scale ruderal vegetation associations can be nested within alliances of largely non-ruderal vegetation or much broader suites of ruderal groups or macrogroups. Can this terminology and other components of the NVC be used to effectively define and track multiple types of novel vegetation? Through exploration of the current content of the NVC I explore the possible ways it can be used to clarify the extent and types of vegetation that may be considered “novel”.
Results/Conclusions
Many ruderal vegetation types are tied to anthropogenically reduced or increased natural disturbance frequencies. Some of these are identified in the descriptions of the existing vegetation types. Others require further clarification before they can be defined as novel. Novel vegetation can also be identified by the unusual increase or decrease in cover of key indicator species, such as increase in extent of shade tolerant tree species cover in forests reduced fire frequencies. Novel vegetation conditions can be monitored and tracked using resampling and re-mapping techniques but this may vary in success based on intensity and resolution of the techniques. These techniques are proving to be valuable to demonstrate and clarify the rapidly change palette of vegetation throughout the nation. However, there are further refinements necessary to facilitate the definitions of novel ecosystems through vegetation and increase the importance of the NVC as a tool to quantify their significance to ecologists and land managers.