Differential responses of net ecosystem exchange of carbon dioxide to light and temperature between spring and neap tides in subtropical mangrove forests.

Yiqi Luo,Qing Li,Hui Chen,Weizhi Lu,Guanghui Lin

doi:10.1155/2014/943697

Abstract

The eddy flux data with field records of tidal water inundation depths of the year 2010 from two mangroves forests in southern China were analyzed to investigate the tidal effect on mangrove carbon cycle. We compared the net ecosystem exchange (NEE) and its responses to light and temperature, respectively, between spring tide and neap tide inundation periods. For the most time of the year 2010, higher daytime NEE values were found during spring tides than during neap tides at both study sites. Regression analysis of daytime NEE to photosynthetically active radiation (PAR) using the Landsberg model showed increased sensitivity of NEE to PAR with higher maximum photosynthetic rate during spring tides than neap tides. In contrast, the light compensation points acquired from the regression function of the Landsberg model were smaller during spring tides than neap tides in most months. The dependence of nighttime NEE on soil temperature was lower under spring tide than under neap tides. All these results above indicated that ecosystem carbon uptake rates of mangrove forests were strengthened, while ecosystem respirations were inhibited during spring tides in comparison with those during neap tides, which needs to be considered in modeling mangrove ecosystem carbon cycle under future sea level rise scenarios.

Highlights

The importance of mangrove to global carbon cycle is well recognized [1,2,3], the processes and mechanisms controlling carbon exchange between mangrove forests and atmosphere and its response to tidal inundation are still poorly understood
The control experiments investigating the tidal effect on the photosynthesis and respiration process of mangrove were largely done at individual level [8,9,10,11]; it is quite difficult if not impossible to generate common mechanisms for large scale ecosystem CO2 exchange under different tidal inundation conditions
Previous analyses of eddy flux data in coastal wetlands revealed that tidal inundation significantly suppressed ecosystem respiration in spring tides comparing to neap tides [18, 19]

Summary

Introduction

The importance of mangrove to global carbon cycle is well recognized [1,2,3], the processes and mechanisms controlling carbon exchange between mangrove forests and atmosphere and its response to tidal inundation are still poorly understood. The control experiments investigating the tidal effect on the photosynthesis and respiration process of mangrove were largely done at individual level [8,9,10,11]; it is quite difficult if not impossible to generate common mechanisms for large scale ecosystem CO2 exchange under different tidal inundation conditions. Previous analyses of eddy flux data in coastal wetlands revealed that tidal inundation significantly suppressed ecosystem respiration in spring tides comparing to neap tides [18, 19].

Methods

Results

Conclusion