Invasion of Prosopis juliflora in native arid grazing lands: competition and dominance

摘要

Explaining and predicting invasion is a multidimensional process involving many variables. To predict invasion by a particular species in any area, knowledge of component species, competition amongst them and disturbance is essential. Such relationship has been studied in grazinglands of Jamnagar district of arid coastal Gujarat. The relative importance values of species growing in sites having varying density and cover of Prosopis juliflora were plotted as Dominance Diversity curve (DD curve). Dominance diversity curves were logarithmic at all sites having P juliflora compared to log normal curve at sites without it. One tenth of abundance of P juliflora in this study emerged as a threshold beyond which it drastically changed dominance diversity relations. Actual relative abundance (RA) of species in sites with and without P juliflora was compared to assess competition effect. Study revealed that P juliflora has adversely affected abundance of climax species Acacia senegal in both types of habitats. Canopy cover analysis was carried out through Relative mixture response (Rm). Occurrence of this plant on both types of protected sites severely affected cover of Maytenus emarginata.