Carbohydrate dynamics of three dominant species in a Chinese savanna under precipitation exclusion

Abstract

The potential impact of drought on the carbon balance in plants has gained great attention. Non-structural carbohydrate (NSC) dynamics have been suggested as an important trait reflecting carbon balance under drought conditions. However, NSC dynamics under drought and the response mechanisms of NSC to drought remain unclear, especially in water-limited savanna ecosystems. A precipitation exclusion experiment was performed to simulate different drought intensities in a savanna ecosystem in Yuanjiang valley in southwestern China. Growth, total NSC concentration and diurnal change of NSC were determined for the leaves and non-photosynthetic organs of three dominant species (Lannea coromandelica, Polyalthia cerasoides and Heteropogon contortus) throughout the growing season. Drought significantly reduced the growth of all the three species. Total NSC concentration averaged ~8.1%, varying with species, organ and sampling period, and did not significantly decrease under drought stress. By contrast, the diurnal change of NSC in these three species increased under drought stress. These results indicate that these three dominant species did not undergo carbon limitation. Thus, relative change in NSC is a more sensitive and effective indicator than carbon reserves in evaluation of plant carbon balance. These findings provide new insights for the understanding of carbon balance and the mechanisms of carbon starvation.

Patterns in nonstructural carbohydrate contents at the tree organ level in response to drought duration

“…Therefore, NSCs in gymnosperms and angiosperms may respond differently to drought (Johnson et al, 2012). However, the impact of drought stress on NSCs is still inconclusive: Some studies have found NSCs reduction in trees under drought (Adams et al, 2013; Galiano, Martínez‐Vilalta, & Lloret, 2011; Piper, 2011), some studies have found that drought stress has no significant effect on NSCs levels (Gruber, Pirkebner, & Florian, 2012; Jin et al, 2018), and other studies have shown NSCs increase under drought (Correia et al, 2018; Crous et al, 2011; Liu et al, 2019).…”

“…The effects of drought on NSCs are related to drought characteristics such as intensity and duration (Anderegg & Anderegg, 2013; Jin et al, 2018; Sala, Woodruff, & Meinzer, 2012). The impact of slight or moderate drought on trees is a gradual process with a slow formation of cavitation followed by slow repair.…”

Precipitation reduction alters herbaceous community structure and composition in a savanna

“…Precipitation reduction experimental plots were set up using rainout shelters, which were described in more detail in Jin, Li, Liu, Liu, Zhang, Sha, et al. (a). The rainout shelters were constructed with a steel frame (7 m in height) and covered with transparent 1.2‐mm polyethylene sheets (permitting over 85% penetration of photosynthetically active radiation) to reduce the net input of precipitation to the soil.…”

“…In order to disentangle the effects of declines in precipitation on plant community structure and composition of savannas, a precipitation manipulation experiment was conducted. Precipitation reduction significantly decreased the growth of woody species in this savanna ecosystem, but the community composition of the overstorey remained unchanged (Jin, Li, Liu, Liu, Zhang, Sha, et al., a). We know little about the impact of precipitation reduction on the community dynamics of the understorey herbaceous layer, so a four‐year study was performed to explore the response of the herbaceous community to declines in precipitation.…”

Response of net primary productivity to precipitation exclusion in a savanna ecosystem

“…The study was conducted at the Yuanjiang Savanna Ecosystem Research Station (23°27′N, 102°10′E, and 551 m above sea level) of the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, in Yunnan province of southwestern China. The soil in the region is classified as ferralic cambisol according to the FAO classification (Jin et al, 2018). Dominant species in this savanna are Lannea coromandelica, Polyalthia cerasoides, Campylotropis delavayi and Heteropogon contortus (Jin and Ou, 2000).…”