Make a detailed outline of your thesis. An ecology thesis is usually at least 20 pages long, so this outline should go over multiple sections, and each section should have various points you are trying to express through data and professional sources.
Organize all sources you are going to quote in your thesis. This can be done on index cards, where you write down a quote on one side, and on the front put what point or section in your thesis the quote pertains to.
Write the abstract for your thesis. The abstract sums up what your thesis is about, and what topics and issues are addressed in your work. The abstract should be brief; no more than 4-5 sentences.
Write a strong introduction where you state the main thesis of the paper, and the major points that support your thesis (most of the time these points will be how you divide your thesis into sections).