Q U A N T I T A T I V E ECOLOGY A N D W O O D L A N D ECOSYSTEM
175
TABLE XVII
Balance Sheet for Plantations of Pinus sylvestris
for the 55 years from the time of planting
Trees
Uptake by trees
Present in living trees
Removed in harvested tree trunks
Left in crowns and roots of harvested
Litter fall from trees (leaves, branches,
Transfer from trees to soil
trees
cones, etc.)
Ground flora
Uptake by ground flora
Present in ground flora
Change in ground flora
Litter fall from ground flora
Total return from trees and ground
Present in litter layers (L, F and H)
Change in litter layers (L, F and H)
Relertsed by decomposition
Average annual uptake by trees and
Average annual change in ecosystem
Average annual removal in tree trunks
Litter
flora
ground flora
132 1933 2272 431 413 4817
36
150 272 64 41 453
5
98 210 42
14 161
48 279 386 80 75 704
43 1406 1404 245 283 3499
91 1685 1790 325 358 4203
72 876 771 169 182 2058
4
22
19
5
3
40
+ 2
- 1
- 4 - 1
- 5 -73
70 877 775 170 187 2 131
I61 2562 2565 495 ,545 6334
6
34
141
30 28 409
+ 6 +24 +115 +22 +I9 +250
161 2538 2450 473 526 6084
3-7
51
55
1 1
1 1
125
+O.A
+ 3
+7 + 2 + 1
+ I 1
t0.1
2
4 < 1 0 * 3
3
~~
Average annual release by decomposition 2.9
46
44
9
10 11 1
D. SOIL CHANGES
Whilst the average annual removal of nutrients in the forest crop is
small compared with that under most agricultural systems, the longterm loss from woodlands by harvesting is considerable. Furthermore,
the organic matter accumulated in woodlands contains large amounts
of nutrients which are transferred from the soil and immobilized in the
organic material. Clearly, if the soil-nutrient reserve is not supplemented
in some way, a gradual depletion of the soil capital would occur as a
woodland matures and is harvested. Since woodlands are frequently
restricted to areas having soils of low fertility, serious soil degradation
could result within a few generations of trees and reduce productivity
(Rennie, 1955).
Numerous instances of change in the chemical and physical proper-
175
TABLE XVII
Balance Sheet for Plantations of Pinus sylvestris
for the 55 years from the time of planting
Trees
Uptake by trees
Present in living trees
Removed in harvested tree trunks
Left in crowns and roots of harvested
Litter fall from trees (leaves, branches,
Transfer from trees to soil
trees
cones, etc.)
Ground flora
Uptake by ground flora
Present in ground flora
Change in ground flora
Litter fall from ground flora
Total return from trees and ground
Present in litter layers (L, F and H)
Change in litter layers (L, F and H)
Relertsed by decomposition
Average annual uptake by trees and
Average annual change in ecosystem
Average annual removal in tree trunks
Litter
flora
ground flora
132 1933 2272 431 413 4817
36
150 272 64 41 453
5
98 210 42
14 161
48 279 386 80 75 704
43 1406 1404 245 283 3499
91 1685 1790 325 358 4203
72 876 771 169 182 2058
4
22
19
5
3
40
+ 2
- 1
- 4 - 1
- 5 -73
70 877 775 170 187 2 131
I61 2562 2565 495 ,545 6334
6
34
141
30 28 409
+ 6 +24 +115 +22 +I9 +250
161 2538 2450 473 526 6084
3-7
51
55
1 1
1 1
125
+O.A
+ 3
+7 + 2 + 1
+ I 1
t0.1
2
4 < 1 0 * 3
3
~~
Average annual release by decomposition 2.9
46
44
9
10 11 1
D. SOIL CHANGES
Whilst the average annual removal of nutrients in the forest crop is
small compared with that under most agricultural systems, the longterm loss from woodlands by harvesting is considerable. Furthermore,
the organic matter accumulated in woodlands contains large amounts
of nutrients which are transferred from the soil and immobilized in the
organic material. Clearly, if the soil-nutrient reserve is not supplemented
in some way, a gradual depletion of the soil capital would occur as a
woodland matures and is harvested. Since woodlands are frequently
restricted to areas having soils of low fertility, serious soil degradation
could result within a few generations of trees and reduce productivity
(Rennie, 1955).
Numerous instances of change in the chemical and physical proper-