April 7, 2012
Last Sunday, I went out to the backyard to check on the volunteer potatoes I thought were growing in the trash barrel of old soil where I’d grown potatoes previously, only to find that the sprouts, which were up about eight inches by then, had taken a decidedly un-potato like turn. Wondering what I had growing there, I pulled one of the sprouts. The small black walnut still attached to the root end told me that my squirrels had decided to play an April Fools Day prank on me, (though they must have started planning the prank last fall.)
I know we’re not supposed to anthropomorphize animals, but it was hard not to imagine a couple of them sitting on their haunches in the walnut tree, tittering into their front paws as I pulled the rest of their walnut garden from the barrel.
Well played, you rascally rodents.
On the other hand, the squirrels and I seem to have come to an agreement about their not digging in my earth boxes and garden since I began leaving bowls of water near the walnut tree out back and the maple tree in the front yard.
The little episode with the squirrels did start me thinking, though, about how stationary plants evolved mechanisms for seed dispersal that sometimes utilize animals to get their seeds dispersed away from the shade of the parent plant.
The dispersal of plant seeds by animals – including birds – is called zoochory. If the seeds travel on the outside of the animal, it’s call epizoochory and the mechanisms may be seeds with barbs, hooks or spines or a sticky mucous that attaches the seed to fur or feather. When the seeds, or fruits containing the seeds, are ingested by the animal, it’s called endozoochory. And, of course, there is the accidental dispersal by squirrels and other seed eating animals that cache the seeds for later use and fail to retrieve them. Smaller seeds can also be dispersed by ants, snails, beetles, bats, fish and turtles.
Even the human animal gets in on the act (called anthropochory), dispersing seeds on their clothing, shoes, cars and other means of transport over surprisingly long distances.
Although epizoochory accounts for only about five percent of seed dispersal, endozoochory can account for up to ninety percent of such dispersal in tropical forests.
Nature, itself, has erected some barriers to seed dispersal in the form of mountain ranges and oceans, (although some plants have managed creative solutions to some of these,) but man has also put up barriers in the form of roads, cities and dams that break up natural habitats and disrupt animal travel and seed dispersal.
As rapid climate change progresses, plants and animals will not have time to adapt in place and will have to migrate to new habitats in order to survive. How will these man-made barriers disrupt that process? And how will those migrations change our own lives?
I was surprised to read, at one site, that, “Analysis of shifts in the biota during the glacial and interglacial periods established that a 2 C change in average earth temperature can have big effects. During the middle Holocene, temperatures in eastern North America were 2 C warmer than at present. Manatees swam off the New Jersey shore, tapirs and peccaries foraged in Pennsylvania, and Cape Cod had a forest like modern-day North Carolina.” http://www.snre.umich.edu/~dallan/nre220/outline21.htm
Most of big agriculture mono-crop farming will probably not survive rapid climate change, especially with the peaking of energy resources on which it is so dependant. Small farmers and home gardeners, who have the chance to be more flexible in what and how we plant, or what we let grow, will fare better, but only if we are careful and observant stewards of our land.
We need to understand how nature works, both in stable and, increasingly, unstable climes; how plants and animals have evolved together to help each other survive and thrive; how we have disrupted that process and, hopefully, how we can put ourselves back into that process in ways that will lessen the disruptions we have caused and make our own careful adaptations possible.
The little April Fools Day prank mother nature and the squirrels played on me last week was harmless. Unless we become willing, active students of nature once again, the prank we have played on ourselves will not be so benign.
- Seed dispersal by ants (eyeonnature.wordpress.com)