Nitrogen deposition promotes tree growth and drives photosynthetic allocation into wood in temperate and boreal forests

Nitrogen deposition promotes tree growth and drives photosynthetic allocation into wood in temperate and boreal forests

Distribution of 25 experimental sites for N addition in temperate and boreal forests around the world. Credit: Zhu Feifei

Human activities have greatly increased emissions of reactive nitrogen (N) into the atmosphere, resulting in increasing global atmospheric nitrogen deposition. Existing experiments on stimulated nitrogen deposition are mainly performed in forests with low background nitrogen deposition, where treatment durations are often short. In China, nitrogen inputs have remained stable at a relatively high level over the past ten years. Our understanding of how tree growth responds to long-term nitrogen supply is limited.

Photosynthetic carbohydrate allocation between different tree organs is an important factor determining the carbon (C) storage capacity of the forest. Nitrogen deposition can affect the allocation of photosynthesis and thus affect the carbon sink capacity of the forest.

A research group led by Prof. Fang Yunting from the Institute of Applied Ecology of the Chinese Academy of Sciences conducted experiments on stimulated nitrogen deposition in larch forest and mixed forest of Qingyuan Forest, the national observation and research station. They monitored tree growth and waste production responses over the period 2014–2021 to detect nitrogen effects on tree growth and carbon allocation.

They also performed meta-analysis on tree growth and carbon distribution data from other stimulated nitrogen deposition experiments in temperate and boreal forests worldwide to investigate whether there are general effects of nitrogen deposition.

According to the researchers, eight years of simulated nitrogen input (50 kg N ha-1 Year-1) increased total biomass gain by 24% in both larch and mixed forest. The CN response of the total biomass was 11 and 10 kg carbon per kg nitrogen in the two forests, respectively.

Furthermore, nitrogen additions increased total litterfall production (9%) and leaf litterfall production (14%) in mixed forest, and the beneficial effect decreased with treatment time. Nitrogen additions increased the ratio of woody biomass gain to litter production (by 34% in larch forest and 8% in mixed forest) in both forests, indicating a stronger promoting effect of nitrogen on woody biomass gain than on litter production.

By integrating tree growth data from nitrogen addition experiments in other temperate and boreal forests worldwide, they found a pattern similar to that in the Qingyuan forests: the simulated nitrogen deposition increased woody biomass increment and leaf litter production by 24% and 9%, on average.

These results imply that nitrogen deposition promotes tree growth and may shift aboveground tree carbon allocation towards woody tissue over foliage in temperate and boreal forests around the world, conducive to enhancing the stable carbon sink of forests in the context of climate change such as global warming is.

This study entitled “Effects of nitrogen deposition on carbon allocation between wood and leaves in temperate forests” was published in plants, people, planet.

More information:
Meixia Gao et al, Effects of nitrogen deposition on carbon allocation between wood and leaves in temperate forests, plants, people, planet (2022). DOI: 10.1002/ppp3.10341

Provided by the Chinese Academy of Sciences

Quote: Nitrogen Deposition Promotes Tree Growth and Drives Photosynthetic Allocation in Wood in Temperate and Boreal Forests (2022, November 21) Retrieved November 21, 2022 from https://phys.org/news/2022-11-nitrogen-deposition-tree -growth- photosynthate.html

This document is protected by copyright. Except for fair trade for the purpose of private study or research, no part may be reproduced without written permission. The content is for informational purposes only.


#Nitrogen #deposition #promotes #tree #growth #drives #photosynthetic #allocation #wood #temperate #boreal #forests

Leave a Comment

Your email address will not be published. Required fields are marked *