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'flcathcring of Ixinelal soil mil rock provides sax nutrients but relevant data on rates of noztht;xting per unit ama under ficlc conditions are unavailable. Wference a betnean inputs and outputs of nutrients for a site .my be taken only as a rough guide to wecthring rates because of the coaplexity of eaoh system, the usu~lly lob; pmcision in wtjaaulls~~ent of system cqononts a:!the existence of long-tern trends in sone oompments. None of the most relevant available input and output dzta for a.fforested catchments, four quoted in Likens et al., (1967) and one in Jmes (19?1), include estincltr;.? of dl possible nutrient inputs and outputs. Although prduction of coqloto nutrient balance sheets for forests is difficult, car,sidemtiofi of av&luble data above as EL whole leads to the conclusion that managed fomst systcns tend to accumlnte nutrients and do not deplete the soil of nutrients excessively as swestetl by hmie (1956) who under-rated the importance of the various nutricnt inputs to the fomst. Rennie prduced some cseful dnt~ on average nutrient uptakes by trees nnd parts of tmes over 50 and. -100 ycar3 and we have wed these on a ndified besis to outimte re~oval a? nutrients in tree stens during forestry operatiorla (Table 6). Bede used published data on yield,- nutriont caposition and dIY weights of trees in European forests as a bcsis for his calaulz-klons, the data coming fro^ 42 originG1 st~ies includhg trees in growtl-1 clcsses I - V on prcdoclinmtly acid s d y soils and soao base-rich soils, Data vmre grouped into p,ines (two species), other conif~rs (the aPec$es) and hardwoods (ei&t species). Rennie did not explain fUZy why he sepamted off pin8 data fror, oth:..r data, but he implied that this was because loa nutrient denand mas expected for this group
Our estjm~tes of nutrient removal (Table 6) exclude brush timber of less thm 7 cm in diameter. If brush tiahor ras removed frm thc aite, the values given would have to be inoreased by about 37-5s ((~a), 54-615 (K) and 69-8% {P). Figures produced by otbr aubhors for individual nutrients for othclr sites (~vington, 1962) &en differ nw3erLcally h r n those given in Tables 5 and G but &l agree in stressing the low percentage of nutriont u?take removed in timber, Itennie did not provide data on N removal so rough estimes of loss jn trunk tiber wen) obtained *am K or Ca loss and the r
Page 1 and 2: Efl:.6 C'f B. r88$ 0tdl.r675 Lrled
Page 3: Content s Introductlon Paee( " ) 't
Page 6 and 7: As pa& of an ecological system, suc
Page 8 and 9: to the ground per unit area and per
Page 10 and 11: sepamte from changes associated wit
Page 12 and 13: 8 worEng oh heather moor, birch and
Page 14 and 15: laboratory incubation studies, comp
Page 16 and 17: 12 d m use of the herbage prductiol
Page 18 and 19: 200000 kg 1 M) ha-'. Grant (pars. o
Page 20 and 21: Pressures exerted on soils and vege
Page 22 and 23: Appreciable mechar~icel damage to v
Page 24 and 25: mtedals, by carbon dioxiae produoed
Page 26 and 27: Although the eWect of tree litter o
Page 28 and 29: B h s (Xersonal com~unication) has
Page 30 and 31: . . harmless and it is the subseque
Page 32 and 33: the soil. pXua vegetation will be a
Page 36 and 37: stressed, nutrients are ruuoved fim
Page 38 and 39: )4 In gener:r1, t!€e roots extond
Page 40 and 41: Some evidence suggests that natural
Page 42 and 43: The effect of tre-g varies with age
Page 44 and 45: Assessment of the importance of the
Page 46 and 47: Fo=sts have an appreciable influeno
Page 48 and 49: 5 '.i .} .X it h H 5e ^5^5 sF^^ n e
Page 50 and 51: a F ..i^8. E -J EE 'E oo o -c4 4 lr
Page 52 and 53: fa!16 J. Part of the nutriont buege
Page 54 and 55: Table 5 hrt of the nutrj-ent bud.go
Page 56 and 57: ISFXRE}, CL S Alsxaniler, V. (197f)
Page 58 and 59: Coulson, C. 3,, Davies, R. I. & Lev
Page 60 and 61: Egner, lI. & Eriksson, n. 0955-196A
Page 62 and 63: Iia.rt, R. A. de J. (1968). Stuert
Page 64 and 65: Lid.dl.o, li. J. & trioore, K. c. (
Page 66 and 67: Pa6e, e. (1968). sone eff€cts of
Page 68 and 69: Stewart, J. B. & Olivcr', S, A, (19
Page 70: wLIde, S. A- (1958), Forest Soits,

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