Agroforestation of Grasslands in Southeast Asia: WaNuLCAS Model Scenarios for Shade-Based Imperata Control During Tree Establishment - Smallholder Tree Growing for Rural Development and Environmental Services - page 138

6.2.2 Model Scenario for the Philippines

Two timber (Eucalyptus deglupta or mindanao gum and Gmelina arborea or white
teak, yemane) and non-timber ( Lansium domesticum or langsat, lansones and
Mangifera indica or mango) trees were selected for the modeling activity of the
shade-based control for Imperata grasslands (Table 6.2). The tree-based hedgerow
systems were grown in Imperata grassland area with an annual rainfall of 1,775 mm
(total rainfall recorded in the project area from January to December 2004) and a
slope of 18 percent. The soil of the study area is Jasaan clay with 1.98 percent to
2.21 percent organic matter (OM) and a bulk density of 0.93 to 1.05 g cm −3 . To
determine the relationship between the relative light captured by Imperata and the
tree canopy width, non-linear regression was done for the simulated data. Based on
the above scenarios, the following parameters were analyzed:

1. Tree growth performance (diameter) when grown in an Imperata grassland
2. Relative light captured/received by Imperata as a function of canopy width of
timber and non-timber trees
3. Shading effect of timber and non-timber trees on control of Imperata growth

Fig. 6.2 Simulation (with Zone 1 kept free of weeds) and measurement (with strip weeding) of
rubber tree diameter in experiments in West Kalimantan (Mulyoutami et al. 2005)

Table 6.2 Systems modeled for the shade-based Imperata control
Tree species

Spacing (m × m) Tree density (ha −1 )

Eucalyptus deglupta 1 × 3 3,000

1 × 9 1,000

Gmelina arborea 1 × 3 3,000

1 × 9 1,000

Lansium domesticum 5 × 5 400

10 × 10 100

Mangifera indica 5 × 5 400

10 × 10 100