Assessment of Stand Types for Phosphorus Acquisition and Internal Utilization Efficiency in a Desert Plant Blepharis sindica (T. Andres.)1

摘要

Impact of stand types (monoculture and polyculture) on phosphorus acquisition efficiency and their subsequent internal utilization efficiency were determined at species level, in a seratonious arid endangered plant, Blepharis sindica. At pure stand phosphorus acquisition efficiency (PAE) was recorded higher during pulse event (rain) while at mixed stand it was recorded more during non-pulse event (summer). This indicates that at pure stand this species rapidly full-fill their P demand during high soil P availability (pulse event), but at mixed stand due to presence of other life forms this species have adjusted their P acquisition efficiency during non-pulse (low soil P), when other associate probably not able to do this. Ordination analysis shows lack of correlation between PAE and PUTIL, indicates that selection of one of these should not affect the other. Regression analysis between P variables and community factors revealed that at species level dominance of B. sindica reflects with its higherP acquisition efficiency; however as the community diversity (Richness, Shannon and Weaver index and evenness) increases the P internal utilization and PUE were inhibited. Thus it can be concluded that both P internal utilization and PUE of B. sindica are largely influenced with temporal factors (Increase and decrease of community diversity during pulse and non-pulse events, respectively). This plant achieved their effective nutrient use through temporal partitioning, through which it full-fill their Prequirements during low resource availability (non-pulse event). Both soil organic carbon and carbon to nitrogen ratio supports PAE in linear fashions. Similarly soil pH also monotonically supports PAE, while soil organic carbon monotonically inhibits QUTIL. The greater nutrient uptake and uptake efficiency in a pure stand reflects narrow niche width of B. sindica and hence it can be conclude that the impact of life-form diversity on nutrient use efficiency is not a static phenomenon.