CO_2 gas-exchange of a whole fores-tree in the field

本研究以13年树龄的白木（Chamaecyparis obtusa (S. et Z.)）人工林中的一棵代表性乔木为研究对象。Endl)。1988年6月，树高为4.9 m，地上1.0 m处茎周长为19.1 cm，茎体积为8.2 dm^3。林木的地上部分用0.2 mm厚的聚氯乙烯薄膜（光合有效辐射透过率约为90%）制成的同化室封闭。通过温度控制器使室内温度与室外温度同步。用红外气体分析仪测定了气室进出口空气中的CO_2含量。用热流量计测量，进入腔室的空气量白天为60 ~ 120m ^ 3h ^<-1>，夜间为10 ~ 60m ^ 3h ^<-1>。用光度传感器测量牙冠上方的辐射量。地上部分的呼吸速率RT （gCO<@D22@>D2 tree<@D1-1@>D1 h<@D1-1@>D1）与室内温度T (C)呈指数相关：R<@D2T@>D2 = R<@D20@>D2.exp(k)。T)，其中R<@D20@>D2和k是每个月的特定系数。呼吸作用的Q<@D10@>D2值（exp(10.k)）在冬季为2.5 ~ 3.0，温度变化为-1.5 ~ 10.5 C；在夏季为1.4 ~ 1.6，温度变化为18 ~ 30 C。说明冬季的Q<@D210@>D2值高于夏季。日总光合作用的计算方法是将日呼吸的净增益加到日呼吸的净增益上，日呼吸的净增益根据上述R<@D2T@>D2 - T关系式计算。日总光合作用P<@D2g@>D2 （gCO<@D22@>D2 tree<@D1-1@>D1 d<@D1-1@>D1）与日照度I （klx.h d<@D1-1@>D1）的关系式为：1/Pg =A/2 + B，其中A和B为各月特定系数。

This research was conducted on a representative tree within a 13-year-old plantation of hinoki (Chamaecyparis obtusa (S. et Z.) Endl.). The tree height, stem girth at 1.0 m aboveground, and stem volume were respectively 4.9 m, 19.1 cm, and 8.2 dm^3 as of June, 1988. The aboveground part of the forest-tree was enclosed with an assimilation chamber made of polyvinyl chloride films 0.2 mm thick (ca.90% transmissivity of photosynthetically active radiation). Temperature inside the chamber was synclonized with that outside the chamber by means of a temperature controller. CO_2 content in air at the inlet and outlet of the chamber was determined with an infrared gas analyzer. The amount of the air entering the chamber was 60 to 120 m^3 h^<-1> in the daytime, while 10 to 60 m^3 h^<-1> in the nighttime, as measured with a thermal flow meter. Radiation was measured above the crown using a photometric sensor.The respiration rate RT (gCO<@D22@>D2 tree<@D1-1@>D1 h<@D1-1@>D1 of the aboveground part was exponentially related to the temperature T ( C) inside the chamber: R<@D2T@>D2 = R<@D20@>D2.exp(k.T), where R<@D20@>D2 and k are coefficients specific to each month. The Q<@D10@>D2 value ("exp(10.k)) for respiration was in the range from 2.5 to 3.0 during the winter season with the temperature variation of -1.5 to 10.5 C, while from 1.4 to 1.6 during the summer season with the temperature variation of 18 to 30 C. This fact shows that the Q<@D210@>D2 has high values in the winter season than in the summer season. The daily gross photosynthesis was assessed from adding the net gain to the daiuly respiration, which was calculated from considering the above equation of the R<@D2T@>D2 - T relation. The relationship between the daily gross photosynthesis P<@D2g@>D2 (gCO<@D22@>D2 tree<@D1-1@>D1 d<@D1-1@>D1) and the daily illuminance I (klx.h d<@D1-1@>D1) was formulated in the form: 1/Pg =A/2 + B, where A and B are coefficients specific to each month.