Drought and eCO2 Effects on Oak Seedlings Growth, Soil Fertility, and Greenhouse Gases Fluxes

Title: Drought and eCO₂ Effects on Oak Seedlings Growth, Soil Fertility, and Greenhouse Gases Fluxes

 

Authors: Rehab Al Mutairi, Nicholas Kettridge and Sami Ullah

 

Objective/Purpose:

This study explores the impact of water stress legacy and elevated CO₂ on oak seedlings' growth, stomatal conductance, soil nutrient availability, and greenhouse gas (GHGs) fluxes. The research aims to unravel the intricate interplay of these factors under controlled glasshouse conditions.

 

Methods/Approach:

The experiment, conducted from mid-May to August 2023 at the University of Birmingham campus, involved oak seedlings grown under ambient CO₂ and elevated CO₂ chambers, subjected to two soil volumetric moisture levels (10% for drought, 30% for non-drought). Various parameters, including oak growth, stomatal conductance, soil nutrient availability, and GHGs flux, were measured and recorded throughout the three-month period. Additional analyses, including biomass, soil extracellular enzyme activities, microbial biomass of N and C, and net N mineralization, were conducted at the experiment's conclusion.

 

Key Findings/Results:

The study revealed compelling insights into the response of oak seedlings to drought stress and elevated CO₂ conditions. Under drought scenarios, both under ambient and elevated CO₂  environments, oak biomass and growth were notably diminished. Particularly, the roots exhibited a substantial increase in biomass, suggesting a coping strategy in search of water and nutrient resources of the seedlings. Stomatal conductance exhibited a decline under elevated carbon dioxide (eCO₂), indicating a water-saving mechanism employed by plants. Additionally, extracellular enzyme activities were impacted by environmental conditions: a reduction was observed under drought stress. This reduction in enzyme functions aligns with a concurrent decrease in nutrient availability, highlighting a correlation between nutrient levels and enzyme activity reduction during drought conditions.

 

Conclusion/Implications:

The findings underscore the vulnerability of oak seedlings to drought stress, highlighting the importance of soil moisture management for their optimal growth. Additionally, the differential response between ambient and elevated CO₂  levels emphasizes the need for nuanced considerations in future climate change scenarios. These insights contribute to our understanding of ecosystem responses to concurrent drought and elevated CO₂ conditions.

 

Keywords:

Oak seedlings, Drought stress, Elevated CO₂, Soil fertility, Greenhouse gas fluxes, Stomatal conductance, Biomass, Microbial biomass, Net N mineralization.