Microhabitat distribution of two Florida scrub endemic plants in comparison to their habitat‐generalist congeners

Abstract

Habitat-specialist species may be restricted to a narrower range of microhabitats than habitat-generalist species. We addressed this hypothesis by comparing microhabitats of two pairs of congeners that differ in habitat specificity and co-occur in one distinct habitat type, Florida rosemary scrub. We characterized microhabitats of rosemary scrub specialists, Polygonella basiramia and Lechea cernua, their habitat-generalist congeners, Polygonella robusta and Lechea deckertii, and random points in the rosemary scrub habitat. Plants of both habitat specialists occurred in microhabitats with significantly more bare sand than plants of habitat-generalist species and random points. Plants of all four species occurred in microhabitats that were farther from dominant shrubs, Ceratiola and Quercus spp., than random points. Seedlings of both habitat specialists grew larger in bare sand microhabitats, whereas ground lichens and litter did not affect seedling growth of the habitat generalists. As the time since fire increases, bare sand cover decreases, Ceratiola density increases, Quercus density remains constant, and shrubs become taller. Physical characteristics, such as soil temperature, soil carbon, and soil moisture, differ slightly with respect to microhabitat. Our results suggest that P. basiramia and L. cernua are specialized on bare sand microhabitats that characterize their preferred habitat, rosemary scrub. Microhabitat specialization may limit the distribution of these rare species.

An improved phylogeny of the Andean tit-tyrants (Aves, Tyrannidae): More characters trump sophisticated analyses

“…First, generalists are more likely to persist through climate shifts and vicariant events due to their broader distributions, larger population sizes (Newman and Pilson, 1997), broader physiological limits (Kellerman et al, 2009), and lower demographic variability (Maliakal-Witt 2004). Second, taxa on the west slope of the Andes and in rain-shadow valleys generally have broader elevational distributions, and these environments exhibit greater climatic heterogeneity across latitudes, elevations, and seasons (Sarmiento, 1986).…”

Effects of forest structure and microhabitat on the distribution and flowering of a rare understory plant, Actaea elata

“…In this study, microhabitat is defined as the ecological conditions that immediately encompass an individual (as in Menges et al, 1999;Svenning, 1999;Maliakal-Witt et al, 2005). To assess the importance of the microhabitat for both plant distribution and the flowering of A. elata individuals, we measured several environmental variables at the four largest populations in 2006.…”

“…Understanding the optimal environmental conditions for endangered species is important because many species' distributions are directly affected by humans (especially through habitat loss and deterioration, Venter et al, 2006) and high natural ecological specificity has been shown to limit the distribution of a number of rare plant species (Hodgson, 1986;Harrison, 1997;Maliakal-Witt et al, 2005). Identifying optimal environmental conditions and managing endangered species in forest ecosystems can be challenging because understory environments change often, for example, through timber harvesting (Maschinski et al, 1997) or as succession proceeds (Valverde and Silvertown, 1998;Lehtila et al, 2006).…”

Germination studies on three critically endangered endemic angiosperm species of the Kashmir Himalaya, India

“…For example, narrow endemic plant species occur in alpine habitats that are characterised by steep slopes, rocky substrate, fewer coexisting species and lower and sparser vegetation (Baskin and Baskin 1988;Matthews et al 1993;Wolf 2001;Lavergne et al 2003). Such habitats represent ecological 'islands' (Pigott and Walters 1954;Maliakal-Witt et al 2005) or 'local refuges' for the persistence of narrow endemic plant species (Albert et al 2001). In addition to other attributes, seed dormancy in the species with restricted distribution can serve to synchronise their germination with favourable environmental conditions in otherwise inhospitable habitats and hence increases the probability of seedling survival and establishment (Baskin and Baskin 1998).…”