In case of pines a higher annual rainfall (more than 1200 mm) facilitates nutrient absorption. But certain species show a negative relationship between their growth and rainfall. In such case how the carbon sequestration will get affected? How can we explain this phenomenon?
Water use efficiency threshold for terrestrial ecosystem carbon sequestration in China under afforestation
By: Gao, Yang; Zhu, Xianjin; Yu, Guirui; et al.
AGRICULTURAL AND FOREST METEOROLOGY Volume: 195 Pages: 32-37 Published: SEP 15 2014
This is a question of optimum water content of soils. Too much water and other biotic interactions begin to take over inhibiting growth. Presumably if the plants are growing more slowly then less carbon is going bvelow ground, however it could also be that the roots have a faster turnover in water logged soils leading to the possibility of more carbon going below ground despite smaller standing biomass. You would need to design some field experiments to answer this question. Stable isotope tracers may help in teasing out what is going on.
Temperate forests are predicted to play a key role as important sinks for atmospheric carbon dioxide, which could be enhanced by nitrogen (N) deposition. The investigation is based at the Harvard Forest (MA) as part of a now 15-year long N amendment study. Foliar N content in red pine (Pinus resinosa) of the high N treatment has significantly increased, but this increase was accompanied by a de-coupling of the photosynthesis–N relationship. In addition needle longevity in the high N trees was significantly lower compared to the control trees. Conifers of the high N treatment did not use the surplus of N to optimize the amount of photosynthetically active metabolites. Instead N accumulated as soluble protein (other than Rubisco), amino acids and chlorophyll. Photosynthetic capacity in the control trees was about 50% higher than in the fertilized trees. These results indicate that the increase in leaf N is not accompanied by a greater capacity for carbon assimilation in the high N treatment. Using a simple model (PnET-Day) of canopy photosynthesis and carbon allocation, we assessed the long-term effect of these physiological changes on ecosystem carbon balance. The model results emphasize and reinforce the large difference between rates of carbon accumulation predicted to occur if net photosynthesis remained linearly related to foliar N concentration, and rates measured in the field.....
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