論文

査読有り
2016年7月

Crown asymmetry in high latitude forests: disentangling the directional effects of tree competition and solar radiation

OIKOS
  • Tuomas Aakala
  • ,
  • Kenichiro Shimatani
  • ,
  • Toshihiro Abe
  • ,
  • Yasuhiro Kubota
  • ,
  • Timo Kuuluvainen

125
7
開始ページ
1035
終了ページ
1043
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1111/oik.02858
出版者・発行元
WILEY-BLACKWELL

Light foraging by trees is a fundamental process shaping forest communities. In heterogeneous light environments this behavior is expressed as plasticity of tree growth and the development of structural asymmetries. We studied the relative influence of neighborhood structure and directional solar radiation on horizontal asymmetry of tree crowns in late-successional high latitude (67-68 degrees N) forests in northern Fennoscandia. We described crown asymmetries as crown vectors (i.e. horizontal vectors from stem center to crown center), which we obtained from canopy maps based on crown perimeter measurements in the field. To disentangle the influence of the two main determinants, inter-tree competition and directionality of above-canopy solar radiation at high latitudes, we applied circular statistical models, utilizing cylindrical distributions, to these data consisting of orientations and intensities of crown asymmetry. At the individual tree level, our model predicted crown asymmetry vectors from the current stand structure, and the predictions became better when the intensity of asymmetry (i.e. crown vector length) was higher. Competition was the main determinant of crown asymmetry for 2/3 of trees, and the model predictions improved when we incorporated the directionality of solar radiation. At the stand-level, these asymmetries had resulted in a small increment of the projected canopy area and an increased regularity of spatial structure. Our circular statistical modelling approach provided a quantitative evaluation of the relative importance of directionality of solar radiation and neighborhood stand structure, showing how both of these factors play a role in formation of crown asymmetries in high latitude forests. This approach further demonstrated the applicability of circular statistical modeling in ecological studies where the response variable has both orientation and intensity.

Web of Science ® 被引用回数 : 11

リンク情報
DOI
https://doi.org/10.1111/oik.02858
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000379609600014&DestApp=WOS_CPL

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