Hey,
If the question is something like "Evaluate traditional and contemporary management strategies of TWO ecosystems at risk" then it is pretty simple. My advice is to go over your dp 5 notes in regards to the two ecosystems you have chosen to study. Your notes should be structured regarding the syllabus dot points.
My advice is to go with this structure
Intro
B1 - Discussion of human/natural impacts upon ecosystems in general.
B2 - Discuss Ecosystem 1's vulnerability and resilience as well as the human impacts which have disrupted the ecosystem's dynamic equilibrium.
B3- Talk about management strategies used
B4 - Evaluate these strategies with ESD.
Repeat this process for the next ecosystem. In the case the question doesn't specify how many ecosystems to talk about, the general rule of thumb is three ecosystems in depth.
Regarding writing a geography essay, they're super simple. Unlike English, they get straight to the point. Basically, use the PEEL method and you'll be all good (I got 20/20 for every essay so trust me, its fine). The differentiating factor is your terminology and knowledge of your ecosystems with respect to the syllabus. Ensure when you discuss the impacts you look at how this affects the ecosystem (cause and effect). Tie in vulnerability and resilience for a more cohesive argument. Define all your terminology (markers love it when you actually know what you're talking about). Furthermore, when you evaluate, you must evaluate against all 4 principles of ESD. Mind you, with essays, don't leave out anything - just include anything you can think of. The less detailed an essay is, the harder it is to break into the 19/20 range.
Hope this helps! PM me if you want examples, I can offer more help if needed.