Canopy architecture of an agroforestry system: initial evaluation of a waveform system

摘要

Eucalyptus (Eucalyptus spp.) is the main tree cultivated for cellulose pulp production in Brazil and is raised in large-scale monocrop plantations based on a two-dimensional system (rows and lines) of trees of the same age and hence height. There are opportunities to incorporate these huge plantations into agroforestry systems to create ecologically designed production systems. Plants respond to environment by modifying their structures, which in turn mediate their relationships with the available solar radiation-the main parameter affecting plant performance, provided other minimum conditions are met. In this way, it is possible to design a new system as a whole in view of maximizing solar radiation absorption and thus productivity. A tridimensional structure intermediated by a planting time scale (the fourth dimension) was designed on a conventional grid system. The Wave Project, which started in 2009, uses this concept to create a canopy with a wave-like appearance and to have production waves spaced in time. Eucalyptus was planted in alleys and monocrop (for comparison purposes) all at the same spacing (3 x 2 m) at different times. The different heights of neighboring Eucalyptus (the third dimension) allowed a much higher solar radiation exposure. With such an arrangement trees were allowed to present architecture modification in relation to those in monocrop conditions. Trees were able to greatly expand their canopies when exposed to increasing solar radiation availability, thus improving their growth rates. The use of the other two dimensions (height and time) is greatly ignored. With the time scale it is possible to design production systems that evolve. The adjustment of the temporal issue to plants' development and systems' architecture management presents a great possibility of increases on production with ecological adjustments-still unexplored.