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As an important part of ecological hydrology, transpiration is the basis for analyzing forest water cycle and healthy growth, and important for forest protection and scientific management. We used thermal diffusion probes (TDP) to continuously monitor sap flow of Picea crassifolia in the Qilian Mountains from 2017 to 2018 to explore water consumption of P. crassifolia, and analyze the main controlling factors for the growth and transpiration of spruce. The results showed that the instantaneous change of P. crassifolia sap flow showed a single-peak curve in sunny days, a multi-peak or double-peak curve in cloudy days, and basically no obvious regularity in rainy days. The sap flow density of Qinghai spruce was consistent with the dynamics of solar radiation. The sap flow started earlier and ended later on sunny days, and lasted for 12 to 14 hours. Due to the high altitude (2700 m), low air temperature, and low vapor pressure difference (VPD) in this area, the overall sap flow density was low, with an average of (0.86±0.49) kg · d-1. On the hourly scale, the instantaneous rate of sap flow was significantly affected by solar radiation and VPD. On the daily scale, soil temperature and soil moisture content of the 0-40 cm layer were significantly related to sap flow density. The spruce sap flow density decreased with the decreases of solar radi-ation, air temperature, and VPD. In the high-altitude forest area of Qilian Mountains, lower soil and air temperature as well as lower VPD and solar radiation were the causes of low sap flow in Picea crassifolia in this area. [ABSTRACT FROM AUTHOR]

Grasslands in Qilian Mountains plays an important role in maintaining the ecological security of western China. To understand soil physical and chemical properties and the distribution characteristics of vegetation, as well as their correlation in different types of grasslands in Qilian Mountains, we measured soil moisture, nutrient content, bulk density, particle composition, and vegetation characteristics in seven types of grassland in Qilian Mountains. The fractal dimension of soil particles, soil organic carbon, total nitrogen and total phosphorus storages in 0-40 cm soil layer, and plant diversity index were calculated. The results showed that there were significant differences in soil physical and chemical properties and vegetation characteristics among different grassland types. Compared with other types of grassland, alpine meadow had higher soil water, nutrient and clay content, but lower bulk density and sand content. Soil organic carbon, total nitrogen and total phosphorus storages in 0-40 cm layer ranged from 3084 to 45247, 164 to 2358 and 100 to 319 g· m-2, respectively, with high contents of organic carbon and total nitrogen and low content of total phosphorus. There was a significant positive correlation between soil total phosphorus storage and plant diversity index, indicating that soil total phosphorus content was the key factor affecting grassland plant diversity in Qilian Mountains. Compared with other grassland types, alpine meadow in Qilian Mountains had better vegetation status, soil moisture, and nutrient conditions. [ABSTRACT FROM AUTHOR]

As an important part of ecological hydrology, transpiration is the basis for analyzing forest water cycle and healthy growth, and important for forest protection and scientific management. We used thermal diffusion probes (TDP) to continuously monitor sap flow of Picea crassifolia in the Qilian Mountains from 2017 to 2018 to explore water consumption of P. crassifolia , and analyze the main controlling factors for the growth and transpiration of spruce. The results showed that the instantaneous change of P. crassifolia sap flow showed a single-peak curve in sunny days, a multi-peak or double-peak curve in cloudy days, and basically no obvious regularity in rainy days. The sap flow density of Qinghai spruce was consistent with the dynamics of solar radiation. The sap flow started earlier and ended later on sunny days, and lasted for 12 to 14 hours. Due to the high altitude (2700 m), low air temperature, and low vapor pressure difference (VPD) in this area, the overall sap flow density was low, with an average of (0.86±0.49) kg·d -1 . On the hourly scale, the instantaneous rate of sap flow was significantly affected by solar radiation and VPD. On the daily scale, soil temperature and soil moisture content of the 0-40 cm layer were significantly related to sap flow density. The spruce sap flow density decreased with the decreases of solar radiation, air temperature, and VPD. In the high-altitude forest area of Qilian Mountains, lower soil and air temperature as well as lower VPD and solar radiation were the causes of low sap flow in Picea crassifolia in this area.

Grasslands in Qilian Mountains plays an important role in maintaining the ecological security of western China. To understand soil physical and chemical properties and the distribution characteristics of vegetation, as well as their correlation in different types of grasslands in Qilian Mountains, we measured soil moisture, nutrient content, bulk density, particle composition, and vegetation characteristics in seven types of grassland in Qilian Mountains. The fractal dimension of soil particles, soil organic carbon, total nitrogen and total phosphorus storages in 0-40 cm soil layer, and plant diversity index were calculated. The results showed that there were significant differences in soil physical and chemical properties and vegetation characteristics among different grassland types. Compared with other types of grassland, alpine meadow had higher soil water, nutrient and clay content, but lower bulk density and sand content. Soil organic carbon, total nitrogen and total phosphorus storages in 0-40 cm layer ranged from 3084 to 45247, 164 to 2358 and 100 to 319 g·m -2 , respectively, with high contents of organic carbon and total nitrogen and low content of total phosphorus. There was a significant positive correlation between soil total phosphorus storage and plant diversity index, indicating that soil total phosphorus content was the key factor affec-ting grassland plant diversity in Qilian Mountains. Compared with other grassland types, alpine meadow in Qilian Mountains had better vegetation status, soil moisture, and nutrient conditions.