Download Full PDF - 41.38 MB - The Society of Irish Foresters

More documents

Recommendations

Info

IRISH FORESTRY included in the overall model. The final model had the form: where: Pi: probability of lodgepole pine regenerating naturally in subcompartment i, ~o,J": parameters fitted by regression, Xl, X 2 , .•. x,,: level of independent variable xn in subcompartment i. Results The second regression model included four factors and an intercept (Table 4). The four factors were: site exposure, drainage status, the percentage of the antecedent crop comprising lodgepole pine and whether or not the antecedent crop had been thinned (Table 5). The residual element of the model was not significant, indicating no significant lack of fit. Table 4. Analysis of variance offitted logistic regression model. Dependent variable Fitted terms Probability of natural regeneration occurrence Constant, exposure, drainage, % of antecedent crop comprising lodgepole pine and whether or antecedent crop thinned Summary of analysis Degrees of deviance mean deviance deviance ratio Regression freedom 8 76.26 9.5321 9.53 Residual 96 63.29 0.6593 Total 104 139.55 1.3418 Table 5. Parameter estimates for the variables in the natural regeneration probability model. Variable Parameter estimate Intercept 3.43 Exposure 1. Sheltered 0.00 2. Moderately exposed -2.97 3. Highly exposed -3.03 Drainage I. Good 0.00 2. Moderate -3.14 3, Poor -5.32 4, Very poor -4.64 Standard error t-value 1.71 2.00 1.18 -2.51 1.32 -2.30 0.92 -3.43 1.20 -4.43 1.36 -3.42 Probability >t 0.045 0.012 0.022 :0;0.001 :0;0.001 :0;0.001 34
IRISH FORESTRY Table 5. continued Variable Parameter Standard t-value Probability estimate error > t Proportion of lodgepole pine in antecedent crop 1. None 0.00 2. < 50% 1.22 1.66 0.74 0.461 3. > 50% 2.46 1.29 1.91 0.056 Thinned 1. No 0.00 2. Yes 1.73 1.05 1.65 0.099 The model showed that thinning increased the probability of natural regeneration after c1earfelling (Figure 1). Thinning the antecedent crop almost doubled the probability of natural regeneration occurring on both highly and moderately exposed sites, with moderate drainage and an antecedent crop of 100% lodgepole pine. On sheltered sites with similar 100 90 ~ ~ E 80 :s -; c tn 70 :§ I.'!! ell c 60 ell --+--- Thin tn ~ ---- No thin ell 50 c '5. ell '0 40 c. ell tn "C .2 30 '0 ~ 20 :0 (II .0 e 10 D.. 0 Sheltered Moderate High Wind exposure Figure 1. Combined effect of thinning and wind exposure on the probability of lodgepole pine regenerating naturally (assumes site is moderately drained and antecedent crop comprised 100% lodgepole pine). 35
Page 2 and 3: -----------------------------------
Page 4 and 5: -----------------------------------
Page 6 and 7: --------------------., Are You BARK
Page 8: GROWING QUALITY forests of the futu
Page 11 and 12: EDITORIAL Seeing the wood and the t
Page 13 and 14: IRISH FORESTRY Most bare-root plant
Page 15 and 16: IRISH FORESTRY Phenology of shoot g
Page 17 and 18: IRISH FORESTRY Data analyses All da
Page 19 and 20: IRISH FORESTRY 60 Seedling height E
Page 21 and 22: IRISH FORESTRY The date of wrenchin
Page 23 and 24: IRISH FORESTRY Root collar diameter
Page 25 and 26: IRISH FORESTRY addition, root growt
Page 27 and 28: IRISH FORESTRY Rook, D.A. 1971. Eff
Page 29 and 30: IRISH FORESTRY 3. maintain rural em
Page 31 and 32: IRISH FORESTRY enhance the organic
Page 33 and 34: IRISH FORESTRY Figure 1. Normal can
Page 35 and 36: IRISH FORESTRY In Britain in simila
Page 37 and 38: IRISH FORESTRY 3. natural regenerat
Page 39 and 40: IRISH FORESTRY McAdam, lH. and Hopp
Page 41 and 42: IRISH FORESTRY regeneration is the
Page 43: IRISH FORESTRY Table 2. continued V
Page 47 and 48: IRISH FORESTRY all are influenced b
Page 49 and 50: IRISH FORESTRY Carey, M.L. and Hend
Page 51 and 52: IRISH FORESTRY Ireland were in need
Page 53 and 54: IRISH FORESTRY Figure 1. Tree locat
Page 55 and 56: IRISH FORESTRY The specimens contin
Page 57 and 58: IRISH FORESTRY TROBI recorded just
Page 59 and 60: IRISH FORESTRY Mechanical propertie
Page 61 and 62: IRISH FORESTRY Table 1. Materials i
Page 63 and 64: IRISH FORESTRY Table 2. Modulus of
Page 65 and 66: IRISH FORESTRY and therefore small
Page 67 and 68: IRISH FORESTRY Conclusions Mechanic
Page 69 and 70: Trees, Woods and Literature - 26 Ji
Page 71 and 72: IRISH FORESTRY seconds. Eventually
Page 73 and 74: Book reviews Sitka spruce in Irelan
Page 75 and 76: IRISH FORESTRY is sketchy and is di
Page 77 and 78: IRISH FORESTRY ics manager. The nur
Page 79 and 80: IRISH FORESTRY 1 indigenous species
Page 81 and 82: IRISH FORESTRY The arrival of these
Page 83 and 84: IRISH FORESTRY • elimination of u
Page 85 and 86: IRISH FORESTRY Tsitsikamma two furt
Page 87 and 88: IRISH FORESTRY light lunch, most of
Page 89 and 90: IRISH FORESTRY than 15 cm in diamet
Page 91 and 92: IRISH FORESTRY Fynbos ueretarion me
Page 93 and 94: IRISH FORESTRY After a guided tour
Page 95 and 96:
IRISH FORESTRY Mairtin 6 Neachtain
Page 97 and 98:
ecco YOU HAVEN'T TRIED? -IT'S TIME
Page 99 and 100:
Many (J{ Northern Ireland's ji:Jres
Page 103 and 104:
Treeshelters and Spirals Discover T
show all

Download Full PDF - 41.38 MB - The Society of Irish Foresters

Create successful ePaper yourself

Delete template?

Save as template?