干旱区生态环境知识资源中心

Estimation of root distributions in natural systems remains challenging due to the difficulties in excavation and easy breakage of fine roots. Identifying lateral fine root distribution is necessary to determine the potential exploitation of spatially and temporally variable nutrient supplies that characterize most arid ecosystems. We estimated this potential by taking field measurements of lateral root distribution of the small herbaceous perennial Cryptantha flava (A. Nels.) Payson using N-15-enriched nutrient solutions wicked into the soil at various distances from study plants. Leaves were subsequently harvested from these plants and analyzed for N isotopic ratios. C. flava plants were capable of N uptake at distances of greater than 1.0 in from the outer edge of their aboveground canopy. The considerable lateral root neighborhood area of C. flava increases the amount of spatially variable N that is exploitable in these low-N soils. The ability to acquire spatially variable N and rapidly translate N uptake into photosynthetic carbon gain are traits that aid C. flava in maintaining its position as a successful subordinate competitor in a community dominated by larger, woody perennials.