[Spatiotemporal characteristics of photosynthetically active radiation in understory of Korean pine and broadleaved mixed forest in Changbai Mountains].
Based on the data of three years successive automatic measurement with five horizontal quantum PAR sensors, this paper studied the spatiotemporal characteristics of photosynthetically active radiation (PAR) in the understory of Korean pine and broadleaved mixed forest in Changbai Mountains, in contrast with above-canopy PAR. It was found that the annual dynamics of above-canopy PAR showed two or more peaks, which was mainly affected by the weather conditions such as cloudy, foggy and rainy events. The annual dynamics of understory PAR followed the same trend of above-canopy PAR in non-growth season, but was steady and lower in numerical value in growth season. On clear days, larger differences were observed in the diurnal variation and frequency distribution of the understory PAR. As for the spatial variation of the understory PAR, the coefficient of variation (CV) was smaller in non-growth season (about 0.15) than in growth season (> 0.22), with the greatest in August. On the clear days in growth season, the understory PAR had a greater spatial variation when the solar elevation angle was between 38 degrees and 48 degrees (at 9:00-10:00 or 13:00-14:00).
Yuan
Feng-Hui
FH
Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
Guan
De-Xin
DX
Wu
Jia-Bing
JB
Wang
An-Zhi
AZ
Shi
Ting-Ting
TT
Zhang
Xiao-Jing
XJ
D000531:Altitude; D002681:China; D017753:Ecosystem; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects*; D028223:Pinus / Q000254:growth & development / Q000502:physiology*; D013472:Sunlight; D014197:Trees / Q000254:growth & development / Q000502:physiology*; D014887:Weather