Why is it better to only collect tree branches rather than cut down an entire tree?
Its a long lasting development.
Sustainable development is that development work which does not degrade the natural resources so that our future generations will also be able to use them.
Sustainable development is also the development that meets the needs of present without compromising the ability of future generation. This development conserves and promotes both the planet and human beings.
This development conserves ecosystem, biodiversity and cultural heritages. It also controls population, increases public participation and develops human resources. Sustainable development also develops the sense of responsibility towards mother nature
If you cut down a tree, you will not have it. If you cut down dead branches of a tree, you will have the tree and you will be benefiting from it.
Let me illustrate sustainable development using one example.
Trees are important. We make furniture from them. We use it to get heat (energy), etc. etc. There is no doubt they are beneficial.
If you have a mature tree, let me say 30 meters long, and if it occupies an area (let me assume 300 square meters), it continues its life. Some branches of it might be dead. You can remove dead branches to get your fuel. Probably every year there will be new dead branches and you will be benefiting from it.
It is sustainable because you protect your tree.
However, if you want to cut down your tree one day and you do it, the tree will not be there. It causes soil erosion, it causes biodiversity loss (such as birds using tree as their nests will disappear).
This is unsustainable. You had a resource but you lost it forever.