Resprouting of herbs in disturbed habitats: is it adequately described by Bellingham-Sparrow's model?

摘要

Severe disturbances may result in a partial or complete removal of above-ground parts of plants. This is usually followed by establishment of new populations from seeds, either persisting in the seed bank or imported from the outside. Alternatively, vegetative resprouting from plant organs surviving the disturbance may ensure development of the plant cover. The later process has received relatively little attention so far. However, its role in re-establishment of severely disturbed vegetation has been recently considered by several authors (Noble and Slatyer 1980, Walker and Chapin 1987. Fahrig ct al. 1994, Bond and Midgley 2001. Dietz et al. 2002). The dominant role of resprouting ( = vegetative regeneration) in vegetation establishment on severely disturbed sites has been appreciated by authors dealing with a single life form (woody plants; Bell 2001. Del Tredici 2001) or studying response of vegetation to disturbance within a plant community (weeds on arable land, water plants communities: Wehsarg 1954. Barrat-Segretain el al. 1998, Combroux et al. 2001). A broader concept covering plant regeneration across several environments and plant groups is so far missing. A promising step forward was made by Bellingham and Sparrow (2000; referred to henceforth as B&S) who developed a graphic model showing frequency distribution of resprouting plants along gradients of disturbance frequency and severity. They found that this distribution is unimodal. According to their model species with a resprouting strategy (i.e. preferentially investing their resources into storage of assimilates and into a bud bank and resprouting after a disturbance) are more abundant at intermediate severity and frequency of disturbance than plants with a seeding strategy (i.e. preferentially investing into seed production). The latter arc favoured when disturbance is moderate and rare (trees) or strong and frequent (annuals). B&S discussed in their paper only woody plants and virtually all examples given concerned trees and shrubs. This resulted in a misunderstanding of their model by Pausas (2001) who applied it to woody plants only. However, the model by B&S does not preclude herbaceous plants (sec their Fig. 3).