Field experimentation in agroforestry is relatively young, and knowledge on rooting patterns and competitive effects of trees is still limited. Agroforestry researchers should bear this in mind and report any information they collect that can contribute to the improvement of field experiments
Tag: shading
Response strategies of woody seedlings to shading and watering over time after topsoil translocation in dry-hot karst region of China
Translocating topsoil from an appropriate donor forest is a promising strategy to restore seriously degraded sites. However, some dominant or constructive species did not survive due to plant stress in the seedling stage, which ultimately led to a poor community structure and low similarity between new communities and donor forest. In this study, we replaced the topsoil of karst rocky desertification with forest topsoil and imposed different shading and watering treatments following quadratic saturation D-optimum design. Richness, abundance, height and base diameter of woody species (trees + shrubs) were measured yearly to construct mathematical equation between them and shade degrees (SD) and water quantity (WQ) by using multiple stepwise regression. Results displayed a positive linear relationship between richness of woody species and SD at the second year of topsoil translocation, which changed to a parabolic relationship at the fifth year with a maximum 30.8 species when SD was 37.5 %. The positive linear relationship between density of woody species, shrubs and trees and SD at the second year transformed into a parabolic relationship at the fifth year, and density reached maximum 6.3, 3.7 and 3.8 seedlings/m2 when SD were 41.7, 38.9 and 45.0%, respectively. In contrast, the density of Paliurus orientalis and Sophora viciifolia turned into a negative linear relationship with SD at the fifth year. Moreover, although the effect of SD and WQ on height of woody species increased over time, shading inhibited base diameter of shrubs and height of Quercus cocciferoides, Sapium sebiferum and Fraxinus malacophylla at the fifth year. We concluded that no-shading and heavy shading reduced species diversity, and light to moderate shading should be recommended in first 2–3 years after topsoil translocation to enhance woody species survival and accelerate similar forest community establishment providing guidance for the management, regeneration and restoration of native forest in semi-arid areas.
Tree-crop interactions: a physiological approach
Agroforestry is rapidly being transformed from an empirical, largely anecdotal collection of beliefs and practices into an emerging science in the field of natural resource management. This book is a major contribution towards this goal, and is aimed at students, research workers and practitioners in agroforestry and applied plant physiology. The authors have applied principles of plant ecology and crop physiology to develop more precise approaches that quantify biological (tree-crop) interactions in agroforestry systems. The various models developed, particularly the tree-crop interactions equation, provide practical but rigorous approaches for both above- and below-ground processes. The book focuses on two basic resources: water and light. Tree-crop interactions for nutrients are not treated in depth as there are very few data on this subject. There are 10 chapters by various authors: (1) A framework for quantifying the various effects of tree-crop interactions (Ong, C. K.); (2) Mixed cropping of annuals and woody perennials: an analytical approach to productivity and management (Ranganathan, R.; Wit, C. T. de); (3) Mulch and shade model for optimum alley-cropping design depending on soil fertility (Noordwijk, M. van); (4) Principles of resource capture and utilization of light and water (Ong, C. K.; Black, C. R.; Marshall, F. M.; Corlett, J. E.); (5) Microclimatic modifications in agroforestry (Brenner, A. J.); (6) The water balance of mixed tree-crop systems (Wallace, J. S.); (7) Biological factors affecting form and function in woody-non-woody plant mixtures (Huxley, P.); (8) Tree-soil-crop interactions on slopes (Garrity, D. P.); (9) Root distribution of trees and crops: competition and/or complementarity (Noordwijk, M. van; Lawson, G.; Soumaré, A.; Groot, J. J. R.; Hairiah, K.); and (10) Woody-non-woody plant mixtures: some afterthoughts.