Case Studies of Growing Stock and Height Growth Evolution in Spanish Forests

Abstract

The objective of this chapter is to analyse the importance of the increment of forest growth rates in Spain during the last 150 years by giving a retrospective view of growth trends of Spanish forests. Two studies were carried out: (1) study of growing stock evolution of the Spanish forests during the past century; (2)study of forest growth evolution at site level of a forest in Central Spain. Data from inventories of large forests all around Spain are used for the first purpose and individual tree stem analysis data (Pinus sylvestris) from Central Spain are used for the second study. Through both studies it is possible to conclude that growing stocks and forest growth followed increasing trends. Increases in growing stocks were caused by changes in silvicultural practices, but changes in site productivity could be associated with changes in climatic and soil conditions. This chapter discusses the relationships between environmental factors and recorded growth increment, concluding that further research efforts are necessary to characterize the processes that drive growth changes.