Water conservation

The differentiation of water use by plants explains the great diversity of Chinese subtropical forests

A mountain humid evergreen broadleaf forest in southwestern Yunnan. Credit: Song Liang

As a subtype of subtropical broadleaf forests, montane moist evergreen broadleaf forest (MMEBF), also known as montane cloud forest, is widely located in the mountainous regions of southwestern China. Water is a key factor in the formation and maintenance of the Chinese MMEBF. However, potential spatio-temporal water use patterns of coexisting trees in Chinese subtropical forests with distinct dry season have not been investigated so far.

In a study published in Agricultural and forest meteorologyresearchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences studied water uptake depths and leaf characteristics related to water use of three canopy tree species co-occurring dominants at different growth stages in a MMEBF in Yunnan, southwest China.

Using stable isotope techniques, researchers revealed the isotopic signatures of different water pools, as well as the spatial and temporal variations in water uptake by the roots of a subtropical forest in south- western China. The isotopic characteristics of the ecosystem’s water reservoirs (fog, soil, stream, lake and groundwater) confirmed the strong water conservation capacity of this subtropical forest.

An interspecific distribution of water acquisition was detected among tree species of similar ages in 2018 (a regular year), but they drew water from the ground at similar depths after experiencing a flood event. drought in 2019. The three dominant canopy tree species formed a niche separation in terms of vertical water acquisition from the soil, having different water use and water transport efficiencies. water, helps them to facilitate the coexistence of species in the MMEBF.

The researchers found a clear time lag of lower soil water content relative to the meteorological dry season, as well as a time lag effect between soil water dynamics and changing water sources. large and medium-sized trees in the MMEBF.

Moreover, the spatio-temporal distribution of water acquisition was observed between trees of different sizes. Tall trees mainly absorbed water from shallow soil layers, while middle trees absorbed soil water from both shallow (0–30 cm) and deep (30–140 cm) soil layers.

However, large and medium trees shifted their main sources of water to deeper soil layers in 2019, which were more water stressed than in 2018. Small trees relied solely on rainfall to recharge soil water from 0 to 30 cm.

“Our findings will provide a scientific basis to explain plant coexistence in terms of water use distribution,” said Song Liang of XTBG.

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More information:
Liang Song et al, Spatio-temporal differentiations in water use of coexisting trees of a subtropical evergreen forest in southwestern China, Agricultural and forest meteorology (2022). DOI: 10.1016/j.agrformet.2022.108862

Provided by Chinese Academy of Sciences

Quote: Differentiation of water use by plants explains the high diversity of Chinese subtropical forests (February 15, 2022) retrieved on February 15, 2022 from https://phys.org/news/2022-02-differentiation-high -diversity-chinese-subtropical.html

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