Integrating Nursery and Planting Activities

The chapter shows how mathematical modeling can help nursery managers to determine how, when, where and which seedlings to produce with increasing levels of productivity, specific mix of different genetic material, higher adequacy of clone-to-site levels and detailed planning for short time horizons. In a systematic approach, the mathematical techniques are presented as the problem becomes more complex. The strategy involves the use of an optimization mathematical planning model divided into nine components: (i) clonal garden production capacity; (ii) mini-stumps availability; (iii) mini-cuttings daily production capacity; (iv) nursery infra-structure; (v) time each clone takes to grow; (vi) matching potential productivity of clones to each planting area; and (ix) length of the planting period after the harvest. The focus is on how planting decisions and operations can be optimized once the manager has the harvesting schedule plan provided at the strategic level. The main decision variable is the starting period when a given set of clonal seedlings begins in the nursery to meet timely the planting needs. The objective is to maximize future production (wood volume or pulp tons). Planting areas are grouped according to soil, climate and other site characteristics to produce homogeneous planted stands. For each group, the optimal choice of clones, plantation density, fertilization levels, irrigation and other silvicultural practices are determined. The spatial distribution of different clones is considered to mitigate the risk of having few clones concentrated in large adjacent areas. The nursery usually starts the production of seedlings for a specific area close to the period of harvesting that area, matching the best clone seedlings to the recommendations prescribed by the forest manager. The model described in this chapter is illustrated by a real case example that synchronizes planting and harvesting in a large scale in Brazil. The optimal synchronization of nursery activities and silvicultural operations requires a detailed planning of all phases in the nursery and in the field. Linear programming techniques have sufficiently supported the integration of seedling production and nursery management, planting and harvesting. These are among the highest costs in any plantation forest budget.