Tree and plant interactions in the agroforestry system: does the management of coffee intensification disrupt the soil hydrological system and pine growth?

With increasing population pressure on forests in Perhutani land, coffee industrial plants are integrated in Pinus merkusii forests as agroforestry systems in the Community-Based Forest Management program especially in Java. This condition raises the research question (1) whether the growth of pine plants is not affected by the integration of coffee plants with various management?, (2) whether with more intensive management of coffee will be able to improve the growth and production of coffee plants? (3) Does the increasing coffee management will decrease the availability of soil water for coffee plant and pine trees?. This research was conducted with a nested design with one research factor, namely coffee management actions. There are 5 types of coffee management treatment namely (1) no management, (2) coffee with pruning, (3) coffee with laid-down the stems, (4) coffee with pruning and combined with fertilization and (5) reducing a half the pine population, with pruned coffee. The conclusion of this study is that pine growth, which is generally planted as a production forest in Perhutani, will experience a very significant decline if it is converted into a coffee-pine-based agroforestry system. However, as a social function of the forest area, the agroforestry system is still recommended if farmers do coffee treatment with regular pruning and fertilization. Perhutani's recommendation by reducing a half the pine population in the age of 10 years is appropriate to facilitate the interaction of coffee and pine so that water and nutrient competition can be reduced.