天目山柳杉树干液流动态及其与环境因子的关系

Dynamics of Stem Sap Flow of Cryptomeria fortunei and Its Relation to Environmental Factors in Mount Tianmu National Nature Reserve

以浙江临安天目山森林生态定位观测站160年生柳杉古树为研究对象,于2007年12月—2008年11月,采用热扩散技术对柳杉树干液流进行连续监测,同步测定相关环境因子,研究了树干液流速率的日变化、季节变化及其与各环境因子的关系。结果表明:晴天和阴天,柳杉树干液流速率日变化均呈现为单峰曲线,最大值一般出现在13:30—15:00,而雨天则无明显的日变化规律;冬、春、夏、秋季柳杉日液流量分别为(44.92±3.76)kg/d、(62.86±3.86)kg/d、(56.59±3.85)kg/d、(53.47±3.55)kg/d;在不同月份,柳杉月液流量存在差异,1月份最小为1 064.30 kg,5月份最大为2 122.62 kg,全年柳杉树干液流总量为19 853.19 kg。回归分析表明,树干液流与环境因子的关系随不同的研究尺度而不同,影响瞬时液流速率的环境因子主要是空气温度和10 cm深处的土壤温度,影响日液流量的环境因子主要是光合有效辐射,影响月液流量的环境因子主要为空气温度和光合有效辐射。

At the Forest Ecosystem Monitoring Station of Mount Tianmu in Lin＇an City,Zhejiang Province（30°20′N,119°23′E）,a 160-year-old Cryptomeria fortunei tree was selected and its sap flow velocity was measured using thermal dissipation probe（TDP,Hukseflux Ltd.,The Netherlands）method from December 31,2007 to November 30,2008.During the same time period,several environmental variables were measured.The aim of this study was to evaluate the diurnal and seasonal variability of stem sap flow velocity in C.fortunei and its relation to environmental factors.A single peak pattern was observed for the daily changes in sap flow velocity of individual C.fortunei tree in fine and overcast days with the peak time occurring at 13：30—15：00,while no significant variation and regular change pattern of sap flow velocity were found in rainy days.The daily sap flow was（44.92±3.76）,（62.86±3.86）,（56.59±3.85） and（53.47±3.55）kg/d in winter,spring,summer and autumn,respectively.The monthly sap flow volume was the lowest in January,1 064.30 kg and the highest in May,2 122.62 kg.The total annual sap flow value was 19 853.19 kg.Regress analysis showed that the relationship between sap flow velocity and environmental factors varied with temporal scales.The major factors that affected stem sap flow at less hour scale were air temperature and soil temperature at depth of 10 cm,but on daily scale solar radiation was the major influencing factor,and on monthly scale air temperature and solar radiation were the major influencing factors.