Evergreen trees

When the last summer was very intense noticed that some trees like Glyrecedia, Teak, Athachakka etc shed their leaves completely and sunlight is reaching the ground. But some trees like mango, jackfruit, mahagony etc retains the leaves and shade the ground. To some extend coconut trees which are surrounded by mango and jackfruit trees were less affected in the summer. Grasses are completely dried out, cover crop Pureria also is dried out. Looking for options which can shade ground in peak summer also, so has to plan more evergreen trees and perennial grasses which can survive summer