Leaf and Community Photosynthetic Carbon Assimilation of Alpine Plants Under in-situ Warming

Abstract

The Tibetan Plateau is highly sensitive to elevated temperatures and has experienced significant climate warming in the last decades. While climate warming is known to greatly impact alpine ecosystems, the gas exchange responses at the leaf and community levels to climate warming in alpine meadow ecosystems remain unclear. In this study, the alpine grass, Elymus nutans, and forb, Potentilla anserina, were grown in open-top chambers (OTCs) for 3 consecutive years to evaluate their response to warming. Gas exchange measurements were used to assess the effects of in-situ warming on leaf- and community-level photosynthetic carbon assimilation based on leaf photosynthetic physiological parameters. We introduced a means of up-scaling photosynthetic measurements from the leaf level to the community level based on six easily measurable parameters, including leaf net photosynthetic rate, fresh leaf mass per unit leaf area, fresh weight of all plant leaves in the community, the percentage of healthy leaves, the percentage of received effective light by leaves in the community, and community coverage. The community-level photosynthetic carbon assimilation and productivity all increased with warming, and the net photosynthetic rate at the leaf level was significantly higher than at the community level. Under elevated temperature, the net photosynthetic rate of E. nutans decreased, while that of P. anserina increased. These results indicated that climate warming may significantly influence plant carbon assimilation, which could alter alpine meadow community composition in the future.

Cleaning up black carbon using plant strategies

“…The implementation required is regeneration in the form of pruning branches, twigs, and leaves. Leaf pruning is a must with the aim of increasing gas and particulate assimilation capacity (61,62). The assimilation capacity includes the absorption of carbon dioxide, which carries various gaseous pollutants.…”

Seed Dormancy and Seedling Ecophysiology Reveal the Ecological Amplitude of the Threatened Endemism Picris willkommii (Schultz Bip.) Nyman (Asteraceae)

“…Therefore, it is not surprising that the basal rosette can grow and accumulate energy reserves during autumn and winter, on the many days with favorable temperatures at this time of year in the area where Picris willkommii lives. The drop in net photosynthesis begins at 25 °C, possibly due to an increase in respiration [ 51 , 52 , 53 ], while increasing transpiration and decreasing water use efficiency. This demonstrates its adaptation to the temperature regime of its natural range [ 52 , 54 ] and is related to the beginning of the senescence process in late spring.…”

“…However, in order to be able to compete successfully against other species, it may need higher light intensities. In addition, the fact that more than 800 μmol m –2 s –1 of photons are needed to reach maximum photosynthetic rates, the optimal WUE is achieved from 550 μmol m –2 s –1 of photons, and the stabilization of Ci occurs from 500 μmol m –2 s –1 , it would indicate that above 500 μmol m –2 s –1 there are no limitations in the carboxylic function in chloroplasts, but between 500 and 800 μmol m –2 s –1 , there could still be some stomatal limitation for photosynthesis [ 53 ].…”

Warming affects leaf light use efficiency and functional traits in alpine plants: evidence from a 4-year in-situ field experiment

“…E. nutans predominantly occupies the upper part of the community and grow in full-sun conditions, while the leaves of P. anserina were restricted to the lower parts of the community close to soil surface. Consequently, they display distinct resource utilization patterns, particularly in terms of light and soil nutrients ( Zhou et al., 2021 ). The upper leaf layer within the canopy typically absorbs light beyond its saturation point and dissipates excess energy through heat dissipation mechanisms.…”

“…The OTC had a 6.4 m 2 surface area, a height of 2 m, a bottom side length of 1.15 m, and a regular octagon form with an outside diameter of 3 m. Open areas (OAs) were developed as control regions with characteristics comparable to those of the OTCs. The detailed layout of the experimental design was mentioned in our previous articles ( Zhou et al., 2021 ).…”