Subdominant species distribution in microsites around two lifeforms at a desert grassland-shrubland transition zone

TitleSubdominant species distribution in microsites around two lifeforms at a desert grassland-shrubland transition zone
Publication TypeJournal Article
Year of Publication2004
AuthorsHochstrasser T., Peters DC
JournalJournal of Vegetation Science
Volume15
Pagination615-622
Date PublishedOctober 1, 2004
ARIS Log Number157294
Keywordsannual, Bouteloua eriopoda, dominant plant, ECOTONE, functional group, Larrea tridentata, scale, shrub invasion, spatial heterogeneity
AbstractIn many vegetation types, plant species diversity is dependent on the abundance of subdominant plants in microsites around dominant plants. Our objective was to compare subdominant abundance in microsites around dominant grasses and shrubs in the same landscape context. We investigated the distribution of subdominant plants in three microsites (canopy, canopy edge and interspace) around individual shrubs (creosotebush, Larrea tridentata) and grasses (black grama, Bouteloua eriopoda) at a grassland-shrubland transition zone that has been encroached by shrubs within the past 50-100 years. Subdominant plants were sampled using plots of variable size according to microsite type and dominant plant size. Contrary to our expectations, subdominant species abundance was higher in microsites around creosote shrubs than in microsites around black grama. Furthermore, differences in species abundance and composition were higher among microsites around grasses than among microsites around shrubs. The distribution of subdominants was mostly explained by their phenological characteristics, which indicates the importance of temporal variation in resources to their persistence. This detailed study of coexistence patterns around dominants revealed ecological contrasts between two dominant lifeforms, but other factors (such as disturbances) have to be taken into consideration to evaluate landscape-scale diversity.
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