森林立地学会誌 森林立地47(1), 2005, 1〜7
Jpn.J.For.Environment
47(1), 1-7 2005
数種の落葉広葉樹とスギの幼齢林分における乾性沈着量と溶脱量について
佐々木重行
福岡県森林林業技術センター
スギ,センダン,ユリノキ,ヤマザクラ,ケヤキの5樹種の幼齢林分で林外雨,林内雨および樹幹流の量と含まれる溶存成分の濃度(Cl-, NO3-, SO42-, NH4+, K+, Ca2+, Mg2+, Na+およびpH)を測定した。これらに含まれる成分量から養分収支法により乾性沈着量,溶脱量の推定を行い樹種特性について検討した。乾性沈着量は各樹種とも,アニオン量とカチオン量はほぼ同じであった。スギの乾性沈着量は全成分とも落葉広葉樹4樹種より2〜4倍多かった。これは,スギが常緑であることと葉の構造が立体的であることなどが原因と考えられた。溶脱量は広葉樹4樹種がスギよりも多かった。溶脱量はカチオンが明らかに多かった。特に,ユリノキのMg2+,Ca2+は林地への供給量の80%以上が溶脱によるものであった。また,ケヤキでは林内雨+樹幹流によるCl-の供給量が多く,これは溶脱によるものと推定された。また,広葉樹では林外雨による供給量以上に溶脱している成分があった。
Shigeyuki Sasaki: Dry deposition and canopy leaching in young stands of some deciduous trees and Japanese cedar.
Dissolved
elements of rain water, throughfall and stemflow in Japanese cedar (Cryptomeria
japonica) and stands of four deciduous trees, Chinaberry (Melia
azedarach), Tulip tree (Liriodendron tulipifera), Wild cherry tree (Purnus
jamasakura) and Japanease zelkova (Zelkova serrat) stands were
analyzed for 1 year. Analyzed elements were Cl-,
NO3-, SO42-, NH4+,
K+, Ca2+, Mg2+, Na+ and pH. The
amount of dry deposition and canopy leaching were estimated by the material
balance approach. Anoins and cations in dry deposition were almost in
equilibrium in the five spices. This equilibrium between anions and cations was
mostly maintained in dry deposition. The annual amounts of dry deposition in
Japanese cedar were two to four times higher than in the deciduous trees. On
the other hand, the annual amounts of canopy leaching in the four deciduous
trees were much higher than in Japanese cedar, especially in the case of Tulip
tree, where more than 80% of Mg2+, Ca2+ was supplied the
forest soil by canopy leaching. In Japanese zelkova, throughfall and stemflow
contained enriched Cl-, which is believed to have derived from
canopy leaching. It was found that some elements supplied to forest soil,
especially cations were enriched by canopy leaching in deciduous stands.
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