Understanding Plant Phenology and its Drivers in a Tropical Semi-arid Landscape

Abstract

Monitoring the phenology of the primary producers of an ecosystem can reveal the dynamics of an ecosystem. This study was conducted in a semi-arid ecosystem in Andhra Pradesh, where moisture is severely limiting, but the landscape still boasts a large diversity. A total of 18 species of trees and shrubs have been monitored fortnightly at the study site for their leaf, flower and fruit phenology since December 2007. This provided a 6-year long-term dataset to describe phenological patterns and examine the relationship between climate and phenology. Majority of the plants were deciduous. Deciduousness of all plants was found to be between the months of February and May. Leaf flush followed shortly after. Flowering in most of the species followed subsequently after leaf flush. Fruiting was observed to happened mostly in the monsoons, and ripe fruits of majority of the plants were concentrated in the dry phase of the year. I further characterised the seasonality in the populations' phenophases. Synchrony and consistency of populations were analysed for their ecological and evolutionary consequences. Leaf flush was found to be more synchronous than flowering and Trees were found to be more consistent than shrubs. Individual consistencies with respect to the population, were explored to further understand population level synchrony. Most species hinted at some level of individual consistency. Leaf flush of inconsistent populations were positively correlated to the first day of rainfall. An irrigation experiment was conducted on two species to verify causality. No response was observed for irrigation. Monitoring phenology can shed light on the plants relationship with both, the abiotic factors, and their biotic interactions.