Small rainfall pulses affected leaf photosynthesis rather than biomass production of dominant species in semiarid grassland community on Loess Plateau of China

Abstract

In the semiarid region Loess Plateau of China, rainfall events, typically characterised as pulses, affect photosynthesis and plant community characteristics. The response of dominant species and grassland community to rainfall pulses was evaluated through a simulation experiment with five pulse sizes (0, 5, 10, 20 and 30 mm) in the semiarid Loess Plateau of China in June and August of 2013. The study was conducted in a natural grassland community dominated by Bothrichloa ischaemum (L.)Keng and Lespedeza davurica (Lax.) Schindl. In June, the leaf photosynthetic rate (Pn), transpiration rate, stomatal conductance, intercellular CO2 concentration of both species and soil water content increased rapidly after rainfall pulses. B. ischaemum was more sensitive to the pulses and responded significantly to 5 mm rainfall, whereas L. davurica responded significantly only to rainfall events greater than 5 mm. The magnitude and duration of the photosynthetic responses of the two species to rainfall pulse gradually increased with rainfall sizes. The maximum Pn of B. ischaemum appeared on the third day under 30 mm rainfall, whereas for L. davurica it appeared on the second day under 20 mm rainfall. Soil water storage (0–50 cm) was significantly affected under 10, 20 and 30 mm rainfall. Only large pulses (20, 30 mm) increased community biomass production by 21.3 and 27.6% respectively. In August, the effect of rainfall on the maximum Pn and community characteristics was generally not significant. Rainfall pulses affected leaf photosynthesis because of a complex interplay between rainfall size, species and season, but might not induce a positive community-level feedback under changing rainfall patterns.

Photosynthetic Properties of Miscanthus condensatus at Volcanically Devastated Sites on Miyake-jima Island

“…The rainfall in June and October were higher than in other months ( Figure A1 , Appendix A ). These are consistent with the previous finding that temporal rainfall may help plant growth [ 55 , 56 ], and indicate that M. condensatus in BL are more sensitive to water deficits. Water deficit is another factor that limits growth, and probably had a large effect on M. condensatus grown in newborn soil.…”

Responses in gross primary production of Stipa krylovii and Allium polyrhizum to a temporal rainfall in a temperate grassland of Inner Mongolia, China

“…The A net of B. gracilis and B. eriopoda increased by 2.2-and 1.8-fold after a 10.0-mm rainfall, respectively. Xiong et al (2017) conducted a study in a semi-arid grassland in Shaanxi Province, China, in which the community was dominated by Bothriochloa ischaemum (C 4 grass) and Lespedeza davurica (C 3 subshrub). The peak net photosynthetic rates of B. ischaemum and L. davurica increased by 1.5-and 1.2-fold after a 10.0-mm rainfall in June, respectively.…”

Soil Moisture Availability at Early Growth Stages Strongly Affected Root Growth of Bothriochloa ischaemum When Mixed With Lespedeza davurica

“…Grasslands play a key role in improving ecological environment in the semiarid and arid regions ( Niu et al, 2016 ; Xiong et al, 2017 ). Rainfall, as the main resource of soil moisture, greatly affects the development of natural grasslands in such areas ( Zhu et al, 2014 ; Gao et al, 2015 ).…”

“…The excellent performance of cassava yield is attributed to the quick recovery of its adventitious root elongation under dramatic fluctuation in soil moisture conditions ( Subere et al, 2009 ). Moreover, root morphological response to soil water improvement is also affected by antecedent soil water contents ( Ogle and Reynolds, 2004 ; Xiong et al, 2017 ; Zhao et al, 2017 ). Tap roots of shrubs distributed in the semiarid Patagonia steppe did not always respond to large precipitation events, only when the 30–60 cm soil layer was relatively dry where their roots distributed ( Golluscio et al, 1998 ).…”

“…Root growth and morphological response to soil moisture fluctuation are also affected by interspecific or intraspecific competition as well as root types ( Ogle and Reynolds, 2004 ; Xiong et al, 2017 ; Zhao et al, 2017 ). Intercropping or mixture of plants with contrasting root traits, such as legume shrub (taproot system)–grass (fibrous root system) mixture, could alleviate intraspecific competition and promote root growth, RSA, and TRL in dry environments, compared with pure stand of the same species ( Xu et al, 2012 , 2015 ; Qiu and Li, 2016 ).…”