A few years ago, Alejandro Ordonez and Jack Williams published a study comparing the speed of range migration to the speed of climate change during 6 periods of change in the last 16,000 years. Jacquelyn Gill described the paper with a bit of context.
They found that northern (leading) edges expanded more rapidly than southern (trailing) edges, and that tree velocities were as fast or faster than the climate velocities for the same interval. They found that not only were tree range shifts paced by climate change in general, but that biotic velocities were faster when climate change was more rapid. Populations at the leading edge were more sensitive than the trailing edge to climate change, suggesting that expansions were climate driven but mortality at the trailing edge was affected by non-climatic factors like biotic interactions. As Ordonez and Williams note, their velocity estimates (-1.7 to 2.7 km/decade) are on the low end of previous pollen-based estimates (1-10 km/decade), but slightly higher than those estimated by McLachlan et al. (<1km/decade). Meanwhile, Loarie’s climate velocity estimates for the next century are higher, ranging from 0.8 km/decade to 12.6 km/decade. To complicate matters, species have been documented to reach average velocities of 6.1 km/decade or 16.9 km/decade in response to the climate change observed in the last few decades.
This is relatively encouraging as far as expectations for trees under current climate change – ranges often expanded northward as fast or faster than the climate changed, and stuck around for awhile in the trailing edge. So far, though, it doesn’t look that rosy this time around.
Their dataset included 30 plant genera, mostly woody angiosperms. Since we mostly work on Pinaceae in the Aitken lab (but see here), I pulled out those genera for a closer look.
These graphs show latitudinal biotic velocity vs. latitudinal climatic velocity. Positive values are northward movement and negative values are southward. In general, the biotic velocity is ahead of the climatic velocity, though the fastest they seem to go is about 2km/decade – not exactly a rapid clip.
I wonder what’s going on with the negative climate velocities at the southern range edge. If climates to the south became more favourable, why would the range shift north?
The data was published with the paper, but as a pdf. A. Ordonez was kind enough to provide me with an excel copy. Code used to generate graphs can be found here.
Zhu, K., Woodall, C. W., & Clark, J. S. (2012). Failure to migrate: Lack of tree range expansion in response to climate change. Global Change Biology, 18(3), 1042–1052. doi:10.1111/j.1365-2486.2011.02571.x
Ordonez, A., & Williams, J. W. (2013). Climatic and biotic velocities for woody taxa distributions over the last 16 000 years in eastern North America. Ecology Letters, 16(6), 773–781. doi:10.1111/ele.12110
Wooah Susannah! Those figures are so interesting! We should talk about it sometime! Thanks a lot. I love this post.
Of course I looked right away on the Northern range plot… The legend is a bit confusing because not in chronological order, but once I got around it I had so many questions tickling me…
How come the 2 most recent periods showed lower biotic than climatic velocity?
In earlier times, do you think ice from the Pleistocene retreated at the same pace as climate? and if not, which one would be more likely to correlate with tree expansion?
Anyway… cool stuff!
Sorry about the funny ordering on the legend!
In the actual paper in Figure 4, they show graphs for each time period with all the taxa and the percentage of those taxa above and below the 1:1 line. For every time period except the 2 most recent, the vast majority (71.4 – 92%) of taxa are above the line. But in the 7 to 4 ka BP and 4 to 1 ka BP periods, only 57.7% of taxa make it above the line. The taxa are also highly clustered, pushing up against the origin. The points are way more spread out in the other time periods.
I didn’t make it clear in this post, but it’s important to note they they aren’t actually looking at the extreme northern and southern range edge – this analysis is for what they called the “core distribution.”
It turns out that 7-1 ka BP was actually pretty stable climate-wise. The 10-7, 7-4, and 4-1 periods were their “relatively slow” climate change groups. Not exactly sure why that would slow northern range expansion?