Gandhiji's environmentalism was based on the following ethical principles: non-violence, truth and persevering the truth; shunning the use of materials obtained by illegitimate means and so on. Gandhiji said that we can use the bounties of nature but not with an element of greed.
Links:
[1] http://admin.indiaenvironmentportal.org.in/reports-documents/gandhi-and-environment
[2] http://admin.indiaenvironmentportal.org.in/category/author/t-n-khoshoo
[3] http://admin.indiaenvironmentportal.org.in/category/publisher/wwf-india
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/mahatma-gandhi
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/women
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/population-trends
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rural-development