Plant life history traits of rare versus frequent plant taxa of sandplains: Implications for research and management trials

I apply a comparative, functional group approach to coastal sandplain grassland taxa in order to examine whether rare plant species share certain aspects of rarity and life history characters that are distinct from their more common, co-occurring congeners in these habitats. I compiled a comparative data set containing 16 variables describing biogeographic distributions, level of imperilment, habitat specialization, vegetative versus sexual reproduction, seed dispersal, and dormancy of 27 closely-related pairs of plant species that contrast in their abundance (infrequent versus common) in coastal sandplain grasslands. Frequent and infrequent species were paired within genera (or closely related genera) and thus distributed equivalently across families to control for phylogenetic bias. Paired comparisons revealed that infrequent species were intrinsically rarer range-wide, and exhibited a narrower range and more habitat specialization than their common relatives. A classification tree distinguished infrequent species from common species on the basis of higher habitat specialization, larger seed size, smaller plant height, less reliance less on vegetative (colonial) reproduction, and tendency toward annual or biennial life history. Research and management steps to reduce competition from larger-satured, colonial, perennial species are recommended for these infrequent species. Basic research involving more species and more data on ecophysiological characters, demography, and competitive interactions are needed to identify critical life history traits that will influence responses to particular management regimes. (C) 2006 Elsevier Ltd. All rights reserved.