Earlier events :: 2014 :: STUDENT Talks

Dry forest seedlings do not alter above-ground biomass in response to a pulsed watering regime

Presented by
Lalitha Krishnan
Ncbs
Authors
Lalitha Krishnan, Mahesh Sankaran

Introduction: What conservation problem or question does your study address?

Dry deciduous forests are a very threatened ecosystem due to land-use change. Climate change induced changes in rainfall to more pulsed regimes, may further threaten dry forests by increasing the intra-seasonal droughts they have to endure, which will affect seedling survival. This study aims to investigate the response of tropical deciduous dry forest trees to more pulsed rainfall regimes using functional traits as predictors of performance.

Methods: What were the main research methods you used?

We conducted a large pot experiment which included 19 species of dry forest tree seedlings which were subjected to 2 rainfall treatments; a control (watered every 3 days) and a pulsed treatment (watered every 12 days), which received the same total amount of water, only frequency of application differed. There were 25 plants of each species in each treatment making a total of 950 seedlings. During the experiment growth measurements were taken every 3 weeks and chlorophyll fluorescence measurements, as an indicator of plant stress, were taken one day prior to watering. After 4 months samples were collected for SLA, LDMC, stomatal density, and SRL and all the plants were harvested and dried for total biomass and root:shoot ratio measurements.

Results: What are your most important results?

We found that plants barely changed their above-ground biomass, and did not show differences in stress levels as measured by chlorophyll fluorescence. Functional traits (SLA and LDMC) were poor predictors of above-ground growth. However the plants did invest below-ground in roots, and we found that root biomass did increase during the experiment. We also found relationships between total biomass and several other functional traits.

Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?

This study has demonstrated that functional traits are a useful tool that can be used to predict how different species will respond to changes rainfall and other environmental variables. We measured the predictive power of different functional traits in response to rainfall changes. These functional traits can be used in forest regeneration projects to aid in selecting appropriate species that may perform better under projected climate conditions of the future.