area site Unit goal weeds layers devices sunlight resources key steps early 1970s three years square meter Weed Removal native trees native plants local ecology practitioners Akira Miyawaki Natural Growth dense planting three seedlings Miyawaki Forest allegianceindia Soil Improvement organic material understory plants Japanese ecologist Æ Water Management fertile environment fast-growing groves intense competition The Miyawaki method Native Plant Species initial establishment Allegiance Enterprise Dense, Mixed Planting afforestation technique natural forest structure successful implementation Allegiance Water Management