The\nclues on which Butterfield and his collaborators from SUNY-Buffalo and the U.S.\nGeological Survey relied come in the form of ancient middens\u2014the nests that packrats\nmake with nearby plant material and inadvertently fossilize with their urine, called\namberat. By analyzing data about what types of seeds and branches appeared in\npackrat middens in the Mojave, Chihuahuan and Sonoran Deserts tens of thousands\nof years ago, Butterfield\u2019s team was able to flip back through the pages of the\ncontinent\u2019s history. There, they found a clear record of which plants moved\nfirst to a more habitable climate during the last 10,000-year period of\nsignificant warming, and which straggled behind.<\/p>\n\n\n\n
Which\nplants tended to move into new territory fastest followed the logic of wind and\nmuscle: being taller (a tree) extends the distance your seeds can travel on the\nwind, and having fruits or seeds eaten by birds or animals like coyotes extends\nthat radius even farther. Grasses and wildflowers closer to the earth don\u2019t\nbenefit as much from wind dispersal, and few have features that attract bird\nand mammal dispersers to eat them, causing them to lag behind larger,\nanimal-dispersed species by an average of 2,000 to 5,000 years. <\/p>\n\n\n\n
![\"Saguaro](\"http:\/\/in.nau.edu\/news\/wordpresst\/uploads\/sites\/153\/wp-content\/uploads\/2019\/07\/Instagram_pic-768x1024.jpg\")
<\/figure><\/div>\n\n\n\n\u201cOur\nresults suggest we can predict how quickly a species can move to a newly\nsuitable habitat based on fairly simple traits,\u201d Butterfield said. <\/p>\n\n\n\n
That\u2019s\nuseful as scientists try to understand better how plants are responding\u2014and\nwill respond\u2014to anthropogenic climate change. <\/p>\n\n\n\n
Why a\nspecies stays longer in a changing climate is less clear-cut than who goes\nfirst. Shorter, small-seeded shrubs tended to stay put the longest, lagging the\nleading edge of a migration by an average of more than 6,000 years. While small\nseeds may persist longer than large ones, Butterfield said, traits don\u2019t seem\nto explain the whole story when it comes to plants that lag.<\/p>\n\n\n\n
To\nassemble a picture of past climates, paleoecologists have long used other clues\nsuch as pollen records drawn from soil cores. But pollen can travel hundreds of\nmeters on the wind and therefore provides a grainier image than the middens,\nwhose builders operated within 30 meters. That smaller range offers a higher\nresolution picture of exactly where a particular species was living and how far\nit moved over millennia. And though middens have been an appealing tool for\nscientists to use for several decades, Butterfield\u2019s team was the first to apply\nmodern \u201cbig data\u201d techniques that allowed them to use \u201cclimate niche estimates\u201d\u2014how\nhot or how dry a climate a species can endure\u2014to estimate how fast plants would\nhave moved if they had kept perfect pace with past climate warming. <\/p>\n\n\n\n
\u201cBy\nzooming out, we\u2019re able to see the full suite of responses plants have to a\nchanging climate,\u201d Butterfield said, \u201cand we see that these impacts are\nlong-lasting.\u201d <\/p>\n\n\n\n
![\"NAU](\"http:\/\/in.nau.edu\/news\/wordpresst\/uploads\/sites\/153\/wp-content\/uploads\/2018\/08\/NAU_primary-281_3514-1-e1536853679171.png\")
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