Appendix 2. Total water vapor flow from forests/woodlands, wetlands, and grasslands, with data and references for calculation and classification of subgroups.

Biome	Subgroup	Climatic zone	Areaa (103 km2)	nb	ET (mm/yr)			Water vapor flow (km3/yr)			Referencesc
					Mean	Low	High	Mean	Low	High
Forest	taiga	boreal	11,560	3	401	380	420	4636	4393	4855
					420						L'Vovich (1979)
					403						Black et al. (1996)
					380						Frank and Inouye (1994)
	predominantly coniferous	temperate	3500	4	487	395	580	1705	1383	2030
					543						Frank and Inouye (1994)
					395						Tiktak and Bouten (1994)
					430						Running et al. (1989)
					580						Yin (1993)
	predominantly deciduous	temperate	8500	4	729	588	964	6199	4998	8194
					588						Frank and Inouye (1994)
					620						Yin (1993)
					745						Luxmoore (1983)
					964						Moran and O'Shaugnessy (1984)
	woodland/woody savanna	temperate	5200	3	416	300	530	2165	1560	2756
					300						Angell and Miller (1994)
					530						L'Vovich (1979)
					419						Joffre and Rambal (1993)
	dry/deciduous/seasonal	tropical/subtropical	7400	2	792	783	800	5857	5794	5920
					783						San José et al. (1995)
					800						L'Vovich (1979)
	wet	tropical/subtropical	5300	3	1245	880	1493	6600	4664	7913
					880						L'Vovich (1979)
					1363						Frank and Inouye (1994)
					1493						Leopoldo et al. (1995)
	savanna/woodland, dry	tropical/subtropical	12,700	2	882	870	894	11,201	11,049	11,354
					870						L'Vovich (1979)
					894						Frank and Inouye (1994)
	wet	tropical/subtropical	1300	3	1267	1100	1500	1647	1430	1950
					1100						L'Vovich (1979)
					1500						L'Vovich (1979)
					1200						L'Vovich (1979)
Subtotal			55,460					40,009	35,271	44,972
Wetland	bog	boreal	651	3	221	200	260	144	130	169	Frank and Inouye (1994)
					202
					200						Rouse (1982)
					260						L'Vovich (1979)
	bog	temperate	488	4	674	456	1020	329	223	498
					456						Boeye and Verheyen (1992)
					490						Mitsch and Gosselink (1993)
					730						Gilvear et al. (1993)
					1020						Mitsch and Gosselink (1993)
	swamp	temperate	41	3	843	670	720	35	27	30
					670						Mitsch and Gosselink (1993)
					1139						Gehrels and Mulamoottil (1990)
					720						Mitsch and Gosselink (1993)
	swamp	subtropical	16	5	1127	930	1277	18	15	20
					930						Mitsch and Gosselink (1993)
					1032						Yin and Brook (1992)
					1317						Dolan et al. (1984)
					1080						Mitsch and Gosselink (1993)
					1277						Abtew (1996)
	swamp d	tropical	508	1	1656	1408	1904	841	715	967	Schaeffer-Novelli et al. (1990)
					1656
Subtotal			1704					1366	1110	1684
Grassland	cool grassland	temperate	6940	16	410	130	633	2843	900	4393
					130						Branson et al. (1969)
					190						Sims et al. (1978)
					205						Liang et al. (1989)
					276						Bokhari and Singh (1974)
					339						Scott and Sudemyer (1993)
					413						Frank and Inouye (1994)
					417						Sims et al. (1978)
					422						Roberts and Roberts (1992)
					450						L´vovich (1979)
					450						Sims et al. (1978)
					450						Stephenson (1990)
					480						Bokhari and Singh (1974)
					530						Sims et al. (1978)
					571						Frank and Inouye (1994)
					600						Stephenson (1990)
					633						Bokhari and Singh (1974)
	warm and hot grassland e	tropical	17,300	7	599	403	862	10,356	6967	14,913
					403						Le Houerou (1984)
					466						Lieth (1975)
					500						L´vovich (1979)
					596						Misra (1979)
					655						Carlson et al. (1990)
					708						Laurenroth (1979)
					862						Weltz and Blackburn (1995)
	montane grassland	temperate	650	4	655	430	951	426	280	618
					430						Sims et al. (1978)
					440						Sims et al. (1978)
					799						Holdsworth and Mark (1990)
					951						Holdsworth and Mark (1990)
	montane grassland f	tropical	650	1	600	402	798	390	261	519
					600						L´vovich (1979)
	dry shrubland	tropical	4000	2	270	225	315	1080	900	1260
					225						Stephenson (1990)
					315						Stephenson (1990)
Subtotal			29,540					15,095	9308	21,702

^a Surface areas for grasslands and forest/woodlands are based on Olson et al.(1983), and for wetlands on Matthews (1983), because total spatial coverage of wetlands corresponds roughly with Olson's database, whereas Matthews' has a finer classification of wetlands categories.
^b Here, n refers to the number of references.
^c For references, see Appendix 4.
^d Low/high values are based on a coefficient of variation of +/- 15%.
^e When annual precipitation P < 600 mm/yr, we assumed that ET = P (i.e.. that there is no blue water flow). This assumption is valid for dry grasslands on a large spatial scale (Le Houerou 1984). For grassland systems with P > 600 mm/yr, 20% runoff was assumed. These assumptions were made due to lack of data on ET from grasslands in tropical regions.
^f Low/high values are based on a coefficient of variation of +/- 33%, which is the average standard deviation of the grassland subgroups with more than two references.