Physiological processes in plantation establishment and the development of specifications for forest planting stock

Abstract

Both the morphological and physiological characteristics of forest planting stock vary widely with nursery culture and environment. Through the control of environmentally determined variation in phenotype, stock can be adapted to both the stress of transplanting from nursery to forest site and the particular environmental conditions of the forest site. Evidence is discussed that indicates that the stress of transplanting is primarily water stress, resulting from (i) the confinement of roots to the planting hole, (ii) poor root–soil contact, and (iii) low root permeability. These deficiencies are overcome by root growth, which is thus a central process in plantation establishment. Root growth depends largely on current photosynthesis. Photosynthesis depends on the assimilation of carbon dioxide at the expense of lost water in transpiration. Transpiration is limited by water uptake and hence depends on root growth. Root growth and photosynthesis in newly planted trees are thus mutually dependent. Because of this relationship, plant water status immediately after planting, or as soon as conditions favorable to root growth occur, is a crucial factor in determining plantation establishment success. High plant tissue water status immediately after planting, or as soon as environmental conditions permit root growth, allows the onset of a positive cycle of root growth supported by photosynthesis and photosynthesis supported by root growth; whereas low tissue water potential immediately after planting can lead to the inhibition or root growth by a lack of photosynthesis and the inhibition of photosynthesis by a lack of root growth. Stock characteristics that enhance plant water status immediately after planting are reviewed and the scope for their control considered. Stock characteristics affecting adaptation to particular planting site conditions, or capable of affecting postestablishment plantation performance, are also discussed.

Response of newly planted Norway spruce seedlings to fertilization, irrigation and herbicide treatments

“…Shoot development, as described by Krutzsch index and growth of the 1998-seedlings during the first 1.5 months indicated that there were little difference between treatments in seedling growth during the first period after planting. During this time, the seedlings were probably more restricted by stress of transplanting than by environmental constraints [5,21]. The length of the second-year leading shoot was shorter than the first-year leading shoot for all treatments.…”

“…Water availability in the soil may be a limiting factor during dry years and competition for water from field vegetation may therefore cause mortality among newly planted seedlings [5,13]. Competition for water varies however significantly between regions.…”

Late-season fertilization of Picea mariana seedlings under greenhouse culture: biomass and nutrient dynamics

“…Although height growth was restricted after budset [33], shoot dry mass increased by 89 to 122% (figure 2) attributed mainly to thickening of the stem and cell walls, and lignification of secondary xylem [7,8]. The late-season reallocation of biomass to roots may also contribute to enhanced outplanting performance because increased root size at planting is often beneficial for subsequent water and nutrient uptake [6,24,30].…”

Drought conditioning improves water status, stomatal conductance and survival ofEucalyptus globulussubsp. bicostataseedlings

“…Water stress, which can be caused by limited contact between roots and soil, low hydraulic conductance of suberized roots and/or root confinement, represents the main constraint for plant survival and growth [3,12,35].…”