『Abstract
　Stemflow is a spatially localized point input of precipitation and solutes at the plant stem and is of hydrological and ecological significance in forested and agricultural ecosystems. The purpose of this review is to: (1) critically evaluate our current understanding of stemflow; (2) identify gaps in our present knowledge of stemflow; and (3) stimulate further research in areas where present knowledge is weak. The review begins by analyzing stemflow drainage and nutrient inputs under diverse vegetal cover. Stemflow inputs are then examined as a function of meteorological conditions, seasonality, interspecific and intraspecific differences among and within species, canopy structure, spatiality, and atmospheric pollutanta in urban environments. Stemflow modeling studies are also reviewed and evaluated. Stemflow yield and chemistry are the result of the interaction of the many complex variables listed. By analyzing each separately, it may be possible to isolate their individual affects on stemflow production and chemistry. A comprehensive understanding of each influencing factor would enable the accurate modeling of stemflow water and nutrient inputs into agricultural and forest soils which may result in the optimization of timber and crop harvests.
　Some areas where present knowledge is particularly weak are: (1) stemflow production and nutrient transfers in northern boreal forests (aspen, birch, conifers) and desert cacti; (2) chemical enrichment of stemflow from live trees charred by forest fires; (3) stemflow yield and nutrient inputs during the winter season; (4) intraspecific variation in stemflow production and chemistry; (5) stemflow chemistry from standing dead trees; (6) influence of canopy structure on stemflow chemistry; (7) understory stemflow generation and nutrient transfer; and (8) stemflow enrichment associated with insect infestations.

Keywords: Stemflow; Forest hydrology; Agricultural hydrology; Nutrient cycling; Canopy structure』

『樹幹流は、植物の幹での空間的に局所的な降水と溶質の点としてのインプットであり、森林および農業生態系において水文学的かつ生態学的に重要なものである。本レビューの目的は次のようなものである：（1）樹幹流についての我々の現時点での理解の程度を厳しく評価すること；（2）樹幹流についての我々の現在の知識の不一致を確認すること；そして（3）現在の知識が足りない領域の研究をさらに奨励すること。本レビューは、異なる植生における、樹幹流排出量と栄養インプットを分析することから始めている。樹幹流はそれから、水文条件、季節性、種間と種内での種間差と種内差、林冠構造、空間性、および都市環境での大気汚染の関数として検討されている。樹幹流モデル化研究もレビューされ評価されている。樹幹流生産量と化学的性質は、挙げられた多くの複雑な変数の相互作用の結果である。それぞれ別々に分析することによって、樹幹流生産量と化学的性質に対する個々の影響を分離することが可能かもしれない。各々の影響する要因を包括的に理解することは、木材や穀物の収穫量を最適化するように、農業と森林土壌への樹幹流水と栄養のインプットを正確にモデル化することを可能にするだろう。
　現在の知識が特に不足しているいくつかの領域は次のものである：（1）北方林（アスペン（ポプラ）、カバノキ、針葉樹（マツ・モミ））および砂漠のサボテンの樹幹流生産と栄養輸送；（2）森林火災で黒焦げになった生木からの樹幹流の化学的富化；（3）冬季における樹幹流生産量と栄養インプット；（4）樹幹流生産と化学的性質の種内変動；（5）立枯れ木からの樹幹流の化学的性質；（6）樹幹流の化学的性質への林冠構造の影響；（7）下層樹幹流の生成と栄養輸送；および（8）昆虫の侵入に伴う樹幹流の富化。』

1. Introduction
2. Stemflow measurement methods
　2.1. Measuring stemflow production and chemistry
　2.2. Interpreting stemflow studies
3. Stemflow hydrology and chemistry in different ecoregions
　3.1. Ecoregion and stemflow generation
　3.2. Ecoregion and stemflow chemistry
　3.3. Evaluation
4. Influence of meteorological conditions on stemlflow generation and chemistry
　4.1. Meterological conditions and stemflow yield
　4.2. Meterological conditions and stemflow chemistry
　4.3. Evaluation
5. Seasonality
　5.1. Stemflow yield and seasonality
　5.2. Seasonality and the chemical enrichment of stemflow
　5.3. Evaluation
6. Interspecific and intraspecific variation in stemflow hydrology and chemistry
　6.1. Interspecific stemflow generation
　6.2. Intraspecific stemflow generation
　6.3. Interspecific variation in stemflow chemistry
　6.4. Evaluation
7. Canopy structure
　7.1. Canopy structure and stemflow production
　7.2. Canopy structure and stemflow chemical enrichment
　7.3. Evaluation
8. Spariality of stemflow inputs
　8.1. Spatial variability of stemflow inputs
　8.2. Spatial variability of stemflow chemical inputs
　8.3. Spatial variability of stemflow inputs and geomorphological processes
　8.4. Evaluation
9. Pollutants and stemflow in forest nutrient cycles
　9.1. Stemflow chemistry and pollutants
　9.2. Stemflow and acidic deposition
　9.3. Evaluation
10. Stemflow modeling
　10.1. Stemflow modeling studies
　10.2. Evaluation
11. Conclusion
Acknowledgements
References

Table 1 Range of selected stemflow production values under diverse vegetation cover in tropical, temperate, semi-arid and atid ecorigions（熱帯、温帯、半乾燥帯、乾燥帯地域における異なる植生の樹幹流量についての代表的な値）

Vegetation type 植生型	Stemflow(％ of incident precipitation) 樹幹流（直接の降水量の％）	Reference 文献
Tropical montane rainforest	13.6	Herwitz(1986a)
Tropical rainforest	1.8	Lloyd and de Marques(1988)
Cacao plantation	1.99	Opakunle(1989)
Tropical dry forest	0.6-0.9	Kellman and Roulet(1990)
Tropical montane rainforest	<1.0	Veneklaas and Van Ek(1990)
Tropical rainforest	0.9-1.5	Marin et al.(2000)
Pine-hemlock-beech plots	1.2-9.6	Voigt(1960)
Pinus radiata plantation	3.1-3.9	Crockford and Khanna(1997)
Dry sclerophyll forest	4.8	Crockford and Richardson(1990b)
Subalpine balsam fir forest	3.0-8.0	Olson et al.(1981)
Northern red oak plantation	4.0	Durocher(1990)
Pinus radiata plantation	11.2	Crockford and Richardson(1990b)
Evergreen-broadleaf forest	14.0-20.0	Masukata et al.(1990)
Slash pine forest	0.94-10.4	Tang(1996)
Japanese pine forest	6.6-15.7	Taniguchi et al.(1996)
Chihuahuan desert shrubs	4.0-45.0	Mauchamp and Janeau(1993)
Semi-arid shrubs	0.76-5.14	Navar〔最初のaの頭に´〕(1993)
Chihuahuan desert shrubs	2.0-27.0	Martinez-Meza and Whitford(1996)
Cresotebushes	5.9-26.9	Whitford et al.(1997)
Thornscrub community	3.0	Navar〔最初のaの頭に´〕 et al.(1999)
Laurel forest	1.2-13.6	Aboal et al.(1999)
Mediterranean holm oak forest	2.6-12.1	Bellot et al.(1999)

Table 2 Range of selected stemflow enrichment values of K⁺ and Mg²⁺ in tropical, temperate, and Mediterranean ecoregions（熱帯、温帯、地中海地域における樹幹流のK⁺とMg²⁺の代表値 ）

Vegetation type 植生型	Stemflow　樹幹流		Reference 文献
	K+（kg／ha／年）	Mg2+（kg／ha／年）
Tropical rainforest	1.5-2.8	0.2-0.3	Jordan(1978)
Subtropical eucalypt forest	0.9	1.1	Westman(1978)
Tropical lowland dipterocarp	0.66	0.18	Radzi Abas et al.(1992)
Sessile oak forest	1.48	0.58	Carlisle et al.(1967)
Aspen-black spruce forest	0.01-2.8	0.006-0.5	Verry and Timmons(1977)
Sugar maple-yellow birch	0.8-1.25	0.04-0.05	Foster and Nicholson(1988)
Northern hardwood forest	0.9	0.06	Likens and Bormann(1995)a
Mediterranean holm oak forest	0.3-2.2	0.02-0.2	Bellot and Escarre(1991)
Mediterranean holm oak forest	0.5-2.6	0.06-0.3	Bellot et al.(1999)
a Stemflow nutrient input assumed to be 3％ of total throughfall and stemflow nutrient flux (Ragsdale et al., 1992).

Table 3 Acidic deposition and mean pH of incident bulk precipitation and stemflow（直接の降水および樹幹流についての酸性沈着物とpHの関係）

Area 地域	Species 樹木種	pH		Reference 文献
		Bulk precipitation 全降水	Stemflow 樹幹流
Southeastern Australiaa	Pinus radiata	5.30	4.24	Crockford et al.(1996a,b)
Northern Australiaa	Ceratopelatum virchowii	5.42	4.48	Herwitz(1991)
Northeastern Mexicoa	Quercus spp.	6.59	6.06	Silva and Rodriguez(2001)
Central Nova Scotiab	Acer saccharum	4.3	5.7	Freedman and Prager(1986)
Central Bohemiab	Fagus sylvatica	4.15	4.00	Skrivan〔rの頭にv〕 et al.(1995)
Western Japanb	Ilex rotunda	5.2	5.7	Takagi et al.(1997)
Southeastern Chinab	Cunninghamia lanceolata	6.31	4.14	HouBao et al.(1999)
Northern Bavariab	Fagus sylvatica	4.65	4.60	Chang and Matzner(2000)
a Site not exposed to significant acidic deposition. b Site exposed to significant acidic deposition.