森林立地学会誌 森林立地43〈1),2001,1〜81

Jpn.J.For.Environment 43(1),1-8  2001

 

Differences of soil properties between evergreen broad-leaved

and pine forests in northern Okinawa Island, Japan

 

Xiaoniu Xu *

The United Graduate School of Agricultural Siences, Kagoshima University,

Kagoshima 890-0065, Japan(鹿児島大学大学院連合農学研究科)

Eiji Hirata,Yoshihiro Tokashiki,Tsutomu Enoki and Takeo Shinohara

Faculty of agriculture, University of the Ryukyus, Nishihara,

Okinawa 903-0213, Japan(琉球大学農学部)

 

 Abstract

This study sought to determine the effects of forest type on soil properties. Two forest types were evergreen broad-leaved forest and pine plantation. The level of organic C and total N were similar in the mineral soil under both forest types. The surface mineral soil (A and/or AB horizons) under pine plantation had high pH, high exchangeable Ca2+, low exchangeable Al3+ and available P compared to evergreen broad-leaved forest. No differences occurred for exchangeable K+ and Na+ between both forest types. Exchangeable K+, Ca2+, and Mn2+ showed a steep decrease with depth, while Al3+ and Na+ exhibited little change in both forests. Soil pH increased with depth under evergreen broad-leaved forest, but kept constant under pine plantation. Also, evergreen broad-leaved forest had lower bulk density, and higher total porosity in surface soil horizons than pine plantation. However, there were no differences for physical and chemical properties of lower soil be horizons (B2 horizons) between both forest types. The cluster analysis indicated that the differences in surface soil horizons between the two forest types were contributed to the effects of different forest composition.

Key Word: cluster analysis; exchangeable base; forest type; physical property; soil nutrient; subtropical forest

 

徐小牛・平田永二・渡嘉敷義浩・榎木勉・篠原武夫:沖縄島北部における常緑広葉樹林とリュウキュウマツ林の土壌の理化学性比較

林相の違いが土壌の養分特性に及ぼす影響について検討するために、沖縄東北部における常緑広葉樹林及びリュウキュウマツ林の鉱質土壌層の理化学的性質を調べた。常緑広葉樹林の土壌有機炭素及び全Nは、マツ林との差が認められなかった。表層土壌のpH及び交換性Ca2+は、マツ林が高く、交換性Al3+及び有効性Pは、逆に常緑広葉樹林の方が高くなっていた。また、交換性K+及びNa+は、両者ほとんど差がなかった。土壌pHは、常緑広葉樹林では下層にいくほど高くなるが、マツ林ではほぼ一定となった。物理性については表層土壌の容積重は、常緑広葉樹林のほうが小さかった。孔隙組成からみると、常緑広葉樹林では粗孔隙率が細孔隙率より高く、マツ林では逆に細孔隙率が高くなっていた。しかしながら、下層(B2層)土壌の理化学的性質については、常緑広葉樹林とマツ林に違いが見られなかった。クラスター分析による解析では、林相の違いが、表層土壌の性質に大きく影響することが示唆された。


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