AIR1-CT92-0715 Forest Planning and Management Tools

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AIR Cluster IX - Forestry : Forestry : Wood (Lignocellulose)

	Proposal No:	AIR1-CT92-0715
	Date Prepared:	November 1999
	Source:	Final report summary 1996

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Final report summary 1996

Objectives

The general objectives of the project were the formulation of new growth models by integrating the effects of site condition, silviculture, genetics and wood density and the development of a software package providing information for different tree species concerning details of all harvested trees, the radial distribution of tree ring width and densities at various heights and mineral element contents of stems.

Activities

The project includes eight tasks covering growth models, site conditions, silviculture, wood density, mineral nutrition, genetics, information and planning. The original proposal included another task, that related to natural pruning that was eventually removed from the work program. Each task was carried out by an allotted team. Although interaction and collaboration between teams was good, the

the integration of all the results obtained in the different tasks could not be achieved.

Results

It was found that impossible to develop a single comprehensive software package within the time available. Nevertheless, the outcome of the project with its combination of tasks dealing with varying aspects of silviculture, wood properties, genetics, etc., will be of value to forest science and of economic benefits for forest owners. The activities provided new and comprehensive knowledge about several specific subjects, including artificial pruning and the interactions of wood density, genetics and silviculture. It also provided the basis for decisions in relation to growth models and planning.

Growth ModelsThe use of growth models is based, not only their importance as decision-making tools for estimating growth and yield of trees and stands, but also their ability to simulate the impact of different silvicultural treatments and genetics on growth and on wood properties. Two types of models have been derived: models based at the tree level and models based at the stand level. The growth models were fitted to the specific needs of the forest industry of particular countries. Hence, details of these activities beyond discussion of the type of model is not easy to summarise.

Conventional properties (growth and yield estimation depending on site, plantation density, silvicultural treatments, etc.) were incorporated in all of the models, and these were shown capable of delivering reliable results. In addition new and innovative aspects, as for example indicated below, have been considered and incorporated into the models as well:

• impact of genetic effects on models
• effects of tree and stand characteristics on diameter at different tree heights
• distribution of radial increments along the stem and development of the crown base
• analysis and consideration of market demand before setting up assortment tables and combination with economical evaluation
• effects of changing site conditions and simulation of management alternatives.

Although derived for specific purposes, in general the growth models are flexible enough to be adapted to the needs of other users or to be validated with data from other teams.

Artificial Pruning The results from this area has closed gaps in knowledge about the effects of green pruning on tree growth, pathological risks, and wood quality of Norway spruce, the most important conifer in Europe. The results show clearly, that green pruning, moderately and carefully performed, may improve wood quality significantly without increased risks for increment decrease or fungus attacks.

Wood Density For the efficiency of growth models, not only growth patterns, but also correlations between tree growth and physical properties of wood are of importance. The aim of this activity has been to provide input to growth models dealing with wood density and increment distribution investigated in terms of

• the intra ring and intra tree distribution depending on site, genetics and silviculture;
• the correlation between ring width and silivicultural treatment and the impact on veneer quality;
• the variation in relation to ring width, of juvenile and mature wood.

Genetic Effects For improving the quality of growth models information concerning the effects of genetics on growth and wood quality are of importance. These aspects have been investigated for Norway spruce and Douglas fir, with results that showed that wood density is influenced by genotype as well as by growth rates depending on silvicultural practices, weather, and site characteristics.

Nutrient Storage The question of nutrient storage and internal translocations in Norway spruce and Douglas fir have been investigated. The objective was to determine the extent to which these fast growing species, characterised by a higher biomass production linked to more intensive silviculture than slow growing species, make higher demands on the ecosystem. From the results it was possible to calculate the mean annual immobilisation of nutrients in the wood and in the bark of these stands. The knowledge concerning the relationships between nutrient exports and harvest intensities may be integrated into growth and yield models as indications of restrictions that might be applied in order to guarantee sustainable forest management.

Informatics The results from the other activities were brought together as software was developed that was flexible enough to incorporate at least part of the results relating to "Growths models". The various data on growth, branching and wood quality relationships gained from the other activities were successfully incorporated into a simulation software (called CEP 2-0) and the outputs interfaced with a log quality simulator. Inputs to this software are: site index, initial spacing and thinning. The initial programme was limited to even aged and pure Norway spruce stands, delivering information for three tree classes (dominant, co-dominant and suppressed trees).

Through linkages with activities on nutrient storage and planning, as well as with results gained from Growth Models and Wood Density, very promising tentative simulations have been performed. The results show the possibility of using an interactive software suitable for simulating the effects of various silvicultural treatments in terms of production, wood quality, economic return and ecological impacts.

Planning The purpose of this activity was two fold:

• providing a decision-making tool for long-term forest planning in even aged stands of Norway spruce by optimising silvicultural management (planting density, thinning strategies, rotation period, etc.) under consideration of risks (windfall, snowbreak) and different growing conditions and by estimating the economic outcome. This enables various choices to be made, for example the optimal rotation time and the appropriate thinning strategy under given ecological and economic conditions and to select alternative strategies based on sensitivity analysis. This activity being complemented that on Growth Modelling and Informatics by extending aspects of silviculture and wood properties investigated from the economic point of view.
• complementing the yield and assortment tables derived in Growth Models for Scots pine with economic evaluations. The results provided a scale for the economic value of Scotch pine stands in terms of gross production value as well as the necessary base for further economic analyses and management of Scots pine stands.