分类： 生物学 >> 植物学 提交时间： 2018-01-22
摘要： Bamboo species—the only herbal trees—have unique structural and physiological characteristics that differ from those of other tree taxa. However, the role of night-time water use in bamboo is poorly understood and has rarely been investigated. We studied day- and night-time sap flow response to culm age and rhizome structure in three age levels (juvenile, mature, and senescent) of Phyllostachys pubescens growing in the Nankun Mountain Natural Reserve, South China. We found that sap flow density and whole-tree hydraulic conductance decreased with culm age. After cutting, day-time sap flow and night-time water recharge decreased obviously. In addition, night-time water recharge accounted for the largest proportion (up to 30%) of total daily transpiration in senescent normal bamboos. Therefore, our study indicates that the connected rhizome system and night-time water recharge played significant roles in water compensation during the day and at night in bamboos. Night-time water recharge is especially critical to senescent bamboos because of their weaker transpiration due to the lower whole-tree hydraulic conductance and those are more dependent on night-time water recharge for fulfilling their whole-day water consumption needs.
分类： 生物学 >> 生态学 提交时间： 2017-07-18
摘要： Apparent activation energy (Ea) is one of the most important and sensitive parameters that control soil organic C (SOC) decomposition in prevailing earth system models (ESMs). The variation of apparent Ea is affected by multiple soil environmental factors, among which soil moisture exerts a strong effect. Aiming to better inform temperature sensitivity parameterization in ESMs, here we examined the relationship between apparent Ea and soil moisture with both incubation experiment and field measurement in subtropical forests. We found that apparent Ea declined as soil moisture increased, consistently in both incubation and field experiments. We speculated that this phenomenon was due to altered microbial community composition from changing soil moisture. Our results suggest that future warming and changing precipitation would significantly affect the decomposition of recalcitrant carbon pools in subtropical forests. Lacking representation of the impact of soil moisture on SOC decomposition temperature sensitivity in current ESMs might have biased climate projection.
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