Abies georgei var. smithii is a dominant species playing an important role in protecting biodiversity and sustaining the forestry ecosystems in Southeastern Tibetan Plateau. Stem sap flows of five different diameters ...Abies georgei var. smithii is a dominant species playing an important role in protecting biodiversity and sustaining the forestry ecosystems in Southeastern Tibetan Plateau. Stem sap flows of five different diameters at the breast height(DBH) A. georgei var. smithii samples were monitored continuously with the thermal dissipation probe for the entire growing period in order to understand the water transportation mechanism and the effects of environmental factors on its transpiration and growth. Relative environment factors, temperature and humidity of air, photosynthetically active radiation, rainfall, and wind speed, soil moisture, etc. were measured by the automatic weather stations. Diurnal and seasonal variations in sap flow rate with the different stem diameters and their correlations with meteorological factors were analyzed. The diurnal change in sap flow velocity showed a single-peak curve at the daily time scale, whereas a lower sap flow velocity can be observed in the largest DBH sample tree at night. The maximum average velocity was observed in August, whereas the minimum velocity was observed in January, and a large amount of water evaporated in summer owing to the higher sap flow velocity. In addition, sap flow velocity was closely related to changes in the micrometeorological factors, with average sap flow velocity showing significant linear correlations with air temperature, photosynthetically active radiation, rainfall, and vapor pressure deficit of air and soil moisture. Therefore, some measures, improving the light and temperature conditions, should be taken for protecting A. georgei var. smithii population in the Tibetan Plateau.展开更多
In order to explore the relationship between the time processes of solar radiation and sap flow, sap flow velocity （SFV） of Platycladus orientalis and Pinus tabulaeformis, effective solar radiation （ESR） and other...In order to explore the relationship between the time processes of solar radiation and sap flow, sap flow velocity （SFV） of Platycladus orientalis and Pinus tabulaeformis, effective solar radiation （ESR） and other environmental factors were synchronously monitored for one year in the Beijing Western Mountains by using a thermal dissipation probe （TDP） system and an automatic weather station. Results showed significant differences between changes in diurnal characteristics of ESR and sap flow in sunny days during three seasons. Starting times of sap flow occurred generally 1.5-3 hours later than those of solar radiation and there were small differences between Platycladus orientalis and Pinus tabulaeformis. But peak times and stopping times of sap flow varied considerably with large contrasts in ESR. The duration of sap flow showed clear differences among the seasons owing to the variable rhythms of climate factors in Beijing. Fluctuation amplitude in the duration of sap flow remained relatively stable during the autumn but changed greatly during spring and summer. Changes in diurnal sap flow velocity of both Platycladus orientalis and Pinus tabulaeformis were about 0-3 hours later than those of ESR but with the same configuration. The start of sap flow was mainly induced by the sudden intensification of ESR （sunrise effect）. Seasonal models of SFV indicated that a cubic equation had the best fit. It was more practical to simulate seasonal water consumption models of trees with ESR. In further investigations, these models should be optimized.展开更多
利用热扩散式边材液流探针和Watch dog 小气候观测仪对延庆县上辛庄水土保持站山杨(Populusdavidiana)边材液流速率及其与环境因子的关系进行了观测研究。结果表明,山杨树干边材液流曲线呈宽峰状,表现出明显的昼夜变化和季节变化规律,...利用热扩散式边材液流探针和Watch dog 小气候观测仪对延庆县上辛庄水土保持站山杨(Populusdavidiana)边材液流速率及其与环境因子的关系进行了观测研究。结果表明,山杨树干边材液流曲线呈宽峰状,表现出明显的昼夜变化和季节变化规律,日出后7:00-8:00时液流开始上升,并于13:00-16:00 时达到峰值,然后迅速下降,19:00时速度变慢,至次日日出之前液流微弱,时断时续;7 月份进入雨季,液流速率提高,8 月份由于持续干旱,有所下降,进入9月份,地形雨增加,含水量湿度提高,液流速率又重新上升,10 月份山杨生长变慢,液流速率明显下降。同时,分析了液流速率的波动规律与主要气象因素波动的相关性。展开更多
Using thermal dissipation probe(SF-G), a sample tree’s diurnal sap flow velocity and sap flow density at different trunk heights were monitored in the Quercus acutissima plantation in the Forestry Centre of Taishan A...Using thermal dissipation probe(SF-G), a sample tree’s diurnal sap flow velocity and sap flow density at different trunk heights were monitored in the Quercus acutissima plantation in the Forestry Centre of Taishan Academy of Forestry Science in spring and autumn. 5 days data both in spring and autumn were selected, and spatial variation of trunk water pondage and sap flow was analyzed. In spring, the peak value was higher and fluctuated acutely, and the peak time appeared early and lasted longer than that in autumn. Sap flow velocity at upper trunk section was higher than that at mid and lower trunk section. In autumn, however, sap flow flux at the three trunk sections was very small and similar. Sap flow movement was lagged in order from the lower trunk to upper trunk by 60～120 min in autumn. Spring trunk poundage fluctuated sharply and extended greatly than that in autumn. The relative trunk water restoring time in spring was about 20 h, and 10～12 h longer than that in autumn.展开更多
基金supported by the Tibetan Natural Scientific Foundation of China (13-28)Tibetan Linzhi National Forest Ecological Research Station (2012-LYPT-DW-016)+1 种基金Promotion Plan of Plateau Basic Ecological Academic Team Abilitysupported by CFERN&GENE Award funds on ecological paper
文摘Abies georgei var. smithii is a dominant species playing an important role in protecting biodiversity and sustaining the forestry ecosystems in Southeastern Tibetan Plateau. Stem sap flows of five different diameters at the breast height(DBH) A. georgei var. smithii samples were monitored continuously with the thermal dissipation probe for the entire growing period in order to understand the water transportation mechanism and the effects of environmental factors on its transpiration and growth. Relative environment factors, temperature and humidity of air, photosynthetically active radiation, rainfall, and wind speed, soil moisture, etc. were measured by the automatic weather stations. Diurnal and seasonal variations in sap flow rate with the different stem diameters and their correlations with meteorological factors were analyzed. The diurnal change in sap flow velocity showed a single-peak curve at the daily time scale, whereas a lower sap flow velocity can be observed in the largest DBH sample tree at night. The maximum average velocity was observed in August, whereas the minimum velocity was observed in January, and a large amount of water evaporated in summer owing to the higher sap flow velocity. In addition, sap flow velocity was closely related to changes in the micrometeorological factors, with average sap flow velocity showing significant linear correlations with air temperature, photosynthetically active radiation, rainfall, and vapor pressure deficit of air and soil moisture. Therefore, some measures, improving the light and temperature conditions, should be taken for protecting A. georgei var. smithii population in the Tibetan Plateau.
文摘In order to explore the relationship between the time processes of solar radiation and sap flow, sap flow velocity （SFV） of Platycladus orientalis and Pinus tabulaeformis, effective solar radiation （ESR） and other environmental factors were synchronously monitored for one year in the Beijing Western Mountains by using a thermal dissipation probe （TDP） system and an automatic weather station. Results showed significant differences between changes in diurnal characteristics of ESR and sap flow in sunny days during three seasons. Starting times of sap flow occurred generally 1.5-3 hours later than those of solar radiation and there were small differences between Platycladus orientalis and Pinus tabulaeformis. But peak times and stopping times of sap flow varied considerably with large contrasts in ESR. The duration of sap flow showed clear differences among the seasons owing to the variable rhythms of climate factors in Beijing. Fluctuation amplitude in the duration of sap flow remained relatively stable during the autumn but changed greatly during spring and summer. Changes in diurnal sap flow velocity of both Platycladus orientalis and Pinus tabulaeformis were about 0-3 hours later than those of ESR but with the same configuration. The start of sap flow was mainly induced by the sudden intensification of ESR （sunrise effect）. Seasonal models of SFV indicated that a cubic equation had the best fit. It was more practical to simulate seasonal water consumption models of trees with ESR. In further investigations, these models should be optimized.
基金重庆市教育委员会科学技术研究项目“三峡水库消落带土地利用变化对土壤抗侵蚀的影响研究”(KJQN202000502)重庆师范大学基金项目“酸沉降和土壤施加磷对马尾松林碳氮磷化学计量特征的影响研究”(20XLB005)中挪国际合作项目“N_(2)O emissions from N saturated subtropical forest in South China”(193725/S30)。
文摘Using thermal dissipation probe(SF-G), a sample tree’s diurnal sap flow velocity and sap flow density at different trunk heights were monitored in the Quercus acutissima plantation in the Forestry Centre of Taishan Academy of Forestry Science in spring and autumn. 5 days data both in spring and autumn were selected, and spatial variation of trunk water pondage and sap flow was analyzed. In spring, the peak value was higher and fluctuated acutely, and the peak time appeared early and lasted longer than that in autumn. Sap flow velocity at upper trunk section was higher than that at mid and lower trunk section. In autumn, however, sap flow flux at the three trunk sections was very small and similar. Sap flow movement was lagged in order from the lower trunk to upper trunk by 60～120 min in autumn. Spring trunk poundage fluctuated sharply and extended greatly than that in autumn. The relative trunk water restoring time in spring was about 20 h, and 10～12 h longer than that in autumn.
