Unit mulch variety Benefits approach backyards resilience small area green cover urban areas Requirements mini-forests biodiversity plant growth Dense Forests native plants 20 to 30 years native species diverse forest climate change Miyawaki Forest allegianceindia water retainers unique technique 200 to 300 years careful selection organic fertilizer proper maintenance Urban Afforestation The Miyawaki method native plant species conventional methods resulting plantation perforating materials Allegiance Enterprise small space, fertile soil Allegiance Water Management