Detectability

We’re looking at detectability this week in Environmental Monitoring & Audit. Here are some relevant links:

1. First, check out Guru and Jose’s video explaining why detectability is important in species distribution models (there’s also some bloopers).

2. Then we have Georgia’s post about setting minimum survey effort requirements to detect a species at a site.

3. Another by Georgia about her trait-based model of detection.

4. And finally, a paper showing that Georgia’s time to detection model can efficiently estimate detectability.

And if you want more about detectability, check out a few posts of mine.

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Some statistics to get started

The subject Environmental Monitoring and Audit starts today. We’ll be delving into some statistics, so my introductory chapter on statistical inference for an upcoming book might be useful.

And we’ll be using R, so if you need a quick introduction, check out Liz Martin’s blog.

Edit: And if you want some more information about double sampling (from Angus’ lecture today), please read this blog post.

How many surveys to demonstrate absence?

In the lecture today in Environmental Monitoring and Audit, I mentioned the model examining how much search effort is required to be sufficiently sure of the absence of a species at a site. This was based on a paper by Brendan Wintle et al. (2012).

You can read more about this topic here, with an attempt at an intuitive interpretation of the model, and some links to other examples where the prior probability (base rate) matters.

If you are particularly keen, you can read a copy of the manuscript here.

Reference

Wintle, B.A. Walshe, T.V., Parris, K.M., and McCarthy, M.A. (2012). Designing occupancy surveys and interpreting non-detection when observations are imperfect. Diversity and Distributions 18: 417-424.

Indices for Environmental Monitoring

I did a lecture this week on indices in my subject Environmental Monitoring and Audit. In case you want to know more about my views on indices, check out these blog posts on my research site:

http://mickresearch.wordpress.com/2011/11/14/indices-behaving-badly/

http://mickresearch.wordpress.com/2011/12/02/the-safe-debate/

http://mickresearch.wordpress.com/2012/02/07/an-index-of-gravity-ecology-style/

 

Auditing timber harvest in Victoria

This is an interesting case associated with environmental auditing. A few months ago, the Victoria government lodged a court case against VicForests for alleged illegal logging of rainforest and forest buffers. One interesting aspect is that VicForests is a stated-owned commerical agency; this is almost a case of the government prosecuting itself.

Well, the case has been resolved, for now with an out-of-court settlement. The Victorian government has adjourned the case for year. VicForests has agreed to improve its procedures, work with the Victorian government to better define what constitutes rainforest, and initiate revegetation of 22 ha of rainforest.

I’d be interested to know how the definitions of rainforest are changing.