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

本研究是在13年生黄花木(Chamaecyparis obtusa(S.et Z.)结束。)。截至1988年6月，其树高为4.9m，地上1.0m处的茎周长为19.1 cm，材积为8.2dm^3。林木的地上部分被一个由0.2毫米厚的聚氯乙烯薄膜(约90%的光合作用有效辐射透过率)制成的同化室包围。利用温控器实现室内外温度的同步控制。用红外气体分析仪测定了燃烧室进出口空气中的CO_2含量。根据热流计的测量，白天进入燃烧室的空气量为60至120m^3h；-1；夜间为10至60m^3h；-1。地上部分的呼吸速率Rt(Gco&lt；@D22@&gt；D2 tree&lt；@d1-1@&gt；@d1-1@&gt；d1-1@&gt；d1与室内温度T(C)呈指数关系：R&lt；@D2T@&gt；D2=R&lt；@D20@&gt；D2.exp(K.T)，其中R&lt；@D20@&gt；D2和k是每个月特有的系数。呼吸的Q&lt；@D10@&gt；D2值(exp(10.k))冬季在2.5~3.0之间，温度变化在-1.5~10.5℃之间，而夏季在1.4~1.6之间，温度变化在18~30℃之间，这说明冬季的Q&lt；@D210@&gt；D2比夏季高。通过考虑上述R&lt；@D2T@&GT；D2-T关系式计算出的日净光合量与日呼吸速率相加。日总光合作用P&lt；@D2g@&gt；D2(Gco&lt；@D22@&gt；D2树&lt；@d1-1@&gt；d1 d&lt；@d1-1@&gt；d1)与日照度I(klx.hd&lt；@d1-1@&gt；d1)的关系表示为：1/Pg=A/2+B，其中A和B是每个月特有的系数。

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.