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Pressures exerted on soils and vegetation by agricultuml tr
Bayflel,n (197J) in{ioated paco longthB o? r5-7t ott for $alLera on Scottioh bj.U path8. lJreso velues ar.e con6ider€tly lalt€r than tho6o for sheep o! cattLe (15 ".d 45 cir !. /r. ). Further dil.oct co@lerisoo botwegD prE69u!,ea ex€rtod or. anoas couFactetl by grazlng aninsls anil Man i9 d.ifficuLt because of ilifforonoes 1n locoootion and 1n loceotorla bghavlou! ardcucrent\y LEpolsille because of laak of suitablo alrta fon: use of peths by sb66p ald oattlo or eve!6ge us6 of rhole areas ly !ran. The effoot of tr6.e!!ing by Mar1 dr soil anal vegotation has been mrc,b d.ocuDented ani. discusseA (Lid.dle, 1975, Lu11 1959, llarlen 1974; Speight, 197tt cf atso pp. J - 8) so only ell outtine of the iJ4)e6 of chaEgps rehj.ch occur rcill bo given here. Chsppel1 (19fl) rorting on chalk gre.lalanil, foubd that as trpepllng lncreaseal th€ so1l bulk d.ensity i,Dcreased. anal ra.ter stability of soi.1 aggregates, soil noiature co.'ltent aatl !tu&!era of soil ani.uals all alecredseil. Ch€4ica1 change6 rBre not 6iSnificant or cou]-l nct be testeil becaus€ of bulkfutg ctr sa!0plos but tenal€noies exi.sted. for increasea l-n pet'cebtag€ of ir'on in th6 rgduced (terrous) fotro, aEolurt of a@oniun l{ and peqc€ntage total N and. aearpaae! Lr1 s.eoturt of bitrato, perceotage or8anic C ard C/N tlatio. StoLla! C and N t!"onas l{etr folrna on sheap-paths by D:rj.!!g & naac]-iffe (1962). ooElosLtion of the sward. charges conaid€lably gn heavll.Jr tt'anpled. aleas (Bates 1915; Bayfi€ld., 1971 ; Chappelr, 1971i Daai,es,'19J8; Liddle & Br.8tgL.sdth, 1975t). This has beeo attriluted. to dlffer.enoos in tbe rEsistenco of diffsl9trt speoies to physical daaago (e.g. Bafoa, 1915) and, in tho responso of different er8. soll rooisture status (LiddJ-e & erei.g-SEith, s.trFcieg to changed soil ooDilLtlong 19Db) or soil tenpeletu'€ (Liad.b a Mooft, 1978). Vogetatlolr oover usually alecr€asos with tmnp1ln6 (!atos, 19r5) lut veeetation dj.v€roity es.y alecr€ase or i-ncrease d.opendtng on trenplln8 intonsity ana initial condition of tho !€Betetl-on (Irtddfe, 1975; VtaLaE, 1971 and FI. 5 - 8).
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 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 34 and 35: 'flcathcring of Ixinelal soil mil r
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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