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ECOLOGICAL BASIS OF AGROFORESTRY - CHAPTER 19 (end)

Dịch từ: Tiếng Anh Nông lâm kết hợp (AF) hệ thống đã được chứng minh là có khả năng nhiều hơn một sự kết hợp có lợi nhuận các lô rừng và nông nghiệp sạch (Dupraz et al., 1996). Mặc dù rừng chăn thả ĐÃ Tiếp thu được chấp nhận rộng rãi ở các nước Địa Trung Hải, một cách tiếp cận gần đây đã-được để giới thiệu cây Các khu vực để chăn thả nonwooded. Các lý do để đồng cỏ Promote''trees''on là đa dạng và nhiều người: đến Duy trì một nguồn tài nguyên trên khu vực thức ăn gia súc ở đâu. | 19 Pasture Production and Tree Growth in Agroforestry Systems of Northwest Spain M.P. González-Hernández and M.J. Rozados Lorenzo CONTENTS 19.1 Introduction.361 19.2 Galicia Forest Land and Types of Silvopastoral Systems.362 19.3 Effect of Above and Belowground Factors on Pasture Production and Tree Growth.364 19.3.1 Pasture Production under Different Tree Canopies.364 19.3.2 Soil Water Content under Different Tree Canopies.365 19.3.3 Effect of Nitrogen Fertilization on Pasture Production and Tree Growth.367 19.4 Effect of Tree Spacing on Pasture Production and Tree Growth.369 Acknowledgments.372 References.372 19.1 INTRODUCTION Agroforestry AF systems have been demonstrated as potentially more profitable than a combination of pure agricultural and forest plots Dupraz et al. 1996 . Although forest grazing has gained wide acceptance in the Mediterranean countries a more recent approach has been to introduce trees to nonwooded grazing areas. The reasons to promote trees on pastures are varied and many to maintain a fodder resource on areas where landowners would otherwise have planted forests and excluded rearing activities to diversify farm incomes provide shade and shelter to animals and shift grass production into summer with the help of shade in dry climates Dupraz and Newman 1997 . Perhaps one of the most compelling reasons for including trees on farmlands that are prone to erosion hazards is the role of trees in soil conservation and erosion control Nair 1987 . The importance of AF in soil conservation in its broader sense meaning conservation of fertility and prevention of erosion has been studied and discussed by several authors Wiersum 1984 Lundgren and Nair 1985 Young 1985 1986 . Nair 1987 reported that the inclusion of trees and woody perennials on farmlands can in the long run result in marked improvements in the physical conditions of the soil including permeability water-holding capacity aggregate stability and soil temperature regimes. Although the .