Wednesday, May 15, 2013

Climate change and grazers: coda on paper

Figure 1. Growth curves for bison. Shown are female (a) and male (b) bison from Wichita Mountains, Oklahoma (grey) and Ordway Prairie, South Dakota (black). Unconstrained spline fit to mean weights of each age cohort for each site shown. Ages are jittered to show point density.

Earlier I had summarized some of the results from a cross-site study on bison weights. This was posted right before I was about to submit it for the first time. I ended the post with:

"[Regarding details, I'm about to submit this paper. We'll see how it's met.]"

The paper has been accepted for publication by PLOS One, but that was a semi-rough path to publication. It was reviewed by 3 other journals before being accepted.*** Reviewers mostly got caught up on how best to analyze cross-site data when you have more than one measurement for a site.

***As a note, my record is currently 5 journals reviewing a paper before acceptance. The 15N synthesis was reviewed by Nature (1), PNAS (2 rounds), Global Change Biology (2 rounds), Oecologia (2 rounds), and New Phytologist (2 rounds). The number of rejections seems to have no bearing on how important the paper is. That paper has since been cited 100+ times since its publication in 2009.

The final bison paper will have controversy associated with it. It essentially uses a spatial gradient of climate to help forecast the future. It's less than perfect, but what other option is there for grazers? Experiments without grazers don't incorporate the feedbacks from grazing, which are substantial. Experiments with grazers are unfeasible. Models? Sure, but no way to parameterize. Temporal responses are good ways to narrow predictions, but they don't do well predicting long-term responses with slower feedbacks.

Case in point. Bison from warm sites are smaller than cool sites. Yet, bison gain the same amount of weight in hot years as cool ones.

It's the long-term feedbacks to the N cycle and forage quality that likely are driving the diminished size of bison. And those long-term feedbacks take time to accrue.

In all, climate change effects on grazers is probably one of the most pressing scientific questions we have about grazers. One of the limitations of the paper is transferring knowledge of bison to cattle. But, we just don't have the data on cattle at this time.

Whoever can synthesize cross-site patterns of cattle weight gain will have done some important science.

No comments:

Post a Comment