RAPPORTEUR'S
R E P O R T OF W O R K G R O U P :
I N D I C A T O R S A N D A S S E S S M E N T ON T H E S T A T E OF F O R E S T TOM BRYDGES AES-DOE 4905 Dufferin Street, Downsview, Ontario M 3 H 5T4, Canada
(Received July 1989)
Questions on Forestry
(1) How do we separate 'normal' from human-induced change in forests? (2) How can we predict long-term changes based on backward-looking science? (3) How do we decide on the acceptability of changes? (1) Separation of Normal from Man-made Change (a) Design a monitoring network of stations over areas of different pollution levels and different stand ages; include dendrochronology. (b) Review symptoms of decline and chemical composition of the wood. Compare ecological and eco-illogical symptoms. (c) Establish long-term monitoring of forest growth in areas subjected to experimentation. In some cases we only need to follow what industry is doing. The 'acidification' experiment has been going on for 70 yr. (d) Inventory the forest areas under different conditions (eg. cut, planted, burned etc.) as the first SOE did. (e) Monitor nutrient dynamics and leaching of nitrogen, phosphorus, calcium and other soil ions. Determine if some are in short supply. (f) Measure leaf area and growth of key trees species (leaf area is related to sap-wood area). (g) We also need a measure of wildlife diversity in forests. (2) How Do We Predict Long-term Changes? (a) Combine monitoring and research data into models and apply 'best-educatedguess' approach. (b) Research and monitoring must go together. (2) How Can We Evaluate the Changes? (a) Must first decide on the land-use goals (eg. fiber, wildlife, recreation) (b) Technology will change the interpretation (eg. forest growth will be increased by new technology so the inventory will change). B.C. can double growth Environmental Monitoring and Assessment 15: 301-302, 1990. 9 1990 Kluwer Academic Publishers. Printed in the Netherlands.
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TOM BRYDGES
rate *. There will be conflicts regarding use (eg. logging and burning vs. preservation). (4) Other Factors (a) We have not learned from agriculture about crop rotation. As our forest 'crops' deteriorate, we change the use of the product and this is a continuing practice. (b) History has shown that we use our own forests and then go and get 'somebody elses'. We are running out of places to go. Now we must depend on silviculture to supply greater demand from existing forest areas **
Additional Comments by Kimmins NUTRIENT LEACHING FROM DISTURBED ECOSYSTEMS
The conventional approach of monitoring dissolved nutrients has significant limitations as a measure of the loss of nutrients from the land. Many of the solutions of nutrients entering the stream are rapidly taken out of solution by in stream geochemical processes. The alternative approach of sampling soil solution chemistry using tension or tensionless lysimeters is helpful, but may only sample saturated flow. A better method of sampling average soil solution chemistry over extended periods may be the use of buried resin bags. A mixture of anion and cation exchange resin beads are placed in fine mesh bags and buried at the soil depth of interest. The bag(s) are recovered after some sampling period, eluted, and the resulting solution analyzed for anions and cations. This is an easy and low technology way of comparing soil solution chemistry from site to site and year to year. THE QUESTION OF CROP ROTATION
'Unsuccessful' silviculture in coastal B.C. permits natural succession including a period of occupancy by red alder, to rebuild soil fertility, but delays the growth of a new timber crop. "Successful" silviculture short-circuits succession, eliminating shrub and deciduous tree stages. This minimizes the time to produce the next coniferous crop, but may increase the need for fertilization if forest growth is to be maintained. The U.S. foresters in the PNW are investigating crop rotation of alder-AF-alderAF to duplicate the desirable consequences of natural succession within the framework of crop production. If fertilizers become more expensive, this trend will probably be followed in western Canada. * Prompt regeneration; full stocking; pre-commercial and commercial thinning; fertilization; whole-tree harvesting; shorter rotations; and genetically improved stock would double forest productivity in B.C. ** Most forest industry in Canada is based on 'tenant farming': harvesting an existing crop that they had no hand or investment in creating. Rarely are there any institutional incentives (corporate, governmental) to have more than a short-term perspective. Foresters' concern is with present and short-term future timber supply, staying in business, and competing in the marketplace. Only the larger companies with the bigger 'stake' are interested in these longer-term issues.
R E P O R T OF W O R K G R O U P :
I N D I C A T O R S A N D A S S E S S M E N T ON T H E S T A T E OF F O R E S T TOM BRYDGES AES-DOE 4905 Dufferin Street, Downsview, Ontario M 3 H 5T4, Canada
(Received July 1989)
Questions on Forestry
(1) How do we separate 'normal' from human-induced change in forests? (2) How can we predict long-term changes based on backward-looking science? (3) How do we decide on the acceptability of changes? (1) Separation of Normal from Man-made Change (a) Design a monitoring network of stations over areas of different pollution levels and different stand ages; include dendrochronology. (b) Review symptoms of decline and chemical composition of the wood. Compare ecological and eco-illogical symptoms. (c) Establish long-term monitoring of forest growth in areas subjected to experimentation. In some cases we only need to follow what industry is doing. The 'acidification' experiment has been going on for 70 yr. (d) Inventory the forest areas under different conditions (eg. cut, planted, burned etc.) as the first SOE did. (e) Monitor nutrient dynamics and leaching of nitrogen, phosphorus, calcium and other soil ions. Determine if some are in short supply. (f) Measure leaf area and growth of key trees species (leaf area is related to sap-wood area). (g) We also need a measure of wildlife diversity in forests. (2) How Do We Predict Long-term Changes? (a) Combine monitoring and research data into models and apply 'best-educatedguess' approach. (b) Research and monitoring must go together. (2) How Can We Evaluate the Changes? (a) Must first decide on the land-use goals (eg. fiber, wildlife, recreation) (b) Technology will change the interpretation (eg. forest growth will be increased by new technology so the inventory will change). B.C. can double growth Environmental Monitoring and Assessment 15: 301-302, 1990. 9 1990 Kluwer Academic Publishers. Printed in the Netherlands.
302
TOM BRYDGES
rate *. There will be conflicts regarding use (eg. logging and burning vs. preservation). (4) Other Factors (a) We have not learned from agriculture about crop rotation. As our forest 'crops' deteriorate, we change the use of the product and this is a continuing practice. (b) History has shown that we use our own forests and then go and get 'somebody elses'. We are running out of places to go. Now we must depend on silviculture to supply greater demand from existing forest areas **
Additional Comments by Kimmins NUTRIENT LEACHING FROM DISTURBED ECOSYSTEMS
The conventional approach of monitoring dissolved nutrients has significant limitations as a measure of the loss of nutrients from the land. Many of the solutions of nutrients entering the stream are rapidly taken out of solution by in stream geochemical processes. The alternative approach of sampling soil solution chemistry using tension or tensionless lysimeters is helpful, but may only sample saturated flow. A better method of sampling average soil solution chemistry over extended periods may be the use of buried resin bags. A mixture of anion and cation exchange resin beads are placed in fine mesh bags and buried at the soil depth of interest. The bag(s) are recovered after some sampling period, eluted, and the resulting solution analyzed for anions and cations. This is an easy and low technology way of comparing soil solution chemistry from site to site and year to year. THE QUESTION OF CROP ROTATION
'Unsuccessful' silviculture in coastal B.C. permits natural succession including a period of occupancy by red alder, to rebuild soil fertility, but delays the growth of a new timber crop. "Successful" silviculture short-circuits succession, eliminating shrub and deciduous tree stages. This minimizes the time to produce the next coniferous crop, but may increase the need for fertilization if forest growth is to be maintained. The U.S. foresters in the PNW are investigating crop rotation of alder-AF-alderAF to duplicate the desirable consequences of natural succession within the framework of crop production. If fertilizers become more expensive, this trend will probably be followed in western Canada. * Prompt regeneration; full stocking; pre-commercial and commercial thinning; fertilization; whole-tree harvesting; shorter rotations; and genetically improved stock would double forest productivity in B.C. ** Most forest industry in Canada is based on 'tenant farming': harvesting an existing crop that they had no hand or investment in creating. Rarely are there any institutional incentives (corporate, governmental) to have more than a short-term perspective. Foresters' concern is with present and short-term future timber supply, staying in business, and competing in the marketplace. Only the larger companies with the bigger 'stake' are interested in these longer-term issues.
