Sunday, July 15, 2012

Drought Tolerant Indeed

Last week, the Ozarks finally broke out of that high pressure dome that dominated for over two weeks, that system that stuck us with a stifling heat and incredibly low humidities. In the past couple of weeks, certain lucky areas were subjected to late afternoon thunderstorms, some storms even dumping as much as 3 inches of much needed rain in highly localized places. Sampling, of course, began over a month ago, and before setting out for the Osage Plains on Monday, the glades I sampled looked like this:


When characterizing glade natural communities, the prairie vegetation is often described as "drought tolerant," and the landscape "desert-like" (though many of us are getting away from using that descriptor as it generally pertains to overgrazed glades with no soil left. Visit a glade that hasn't had cows and horses all over it and you'll find a deep, rich glade soil that supports prairie vegetation dominated by warm season grasses without a lot of exposed chert rubble. When glades still have their soil matrix because they haven't been grazed to hell, they are much less desert-like communities than most glades in the state. Anyway...). Nevertheless, glade vegetation on those dry, rocky, mostly southern exposures has adapted to drought and plants continue to bloom on schedule and the leaves of certain plants remain erect:


Others, like the glade obligate Rudbeckia missouriensis, wilts terribly in ultradry conditions:


What has been remarkable, however, is to note the response of glade vegetation to the short bursts of thunderstorms that have occurred in the area. Some of the grasses which remained stunted during the drought have sent up new growth and flowering heads, while others (Aristida purpurascens, in particular) have not been affected at all by the long spate of dry and incredibly hot weather. Recall that in summer 2011, the Ozarks witnessed extended periods of drought, and by fall, with the shorter days and brief fall rains, sexy Aster sericeus flowered and all of the sad little leaves of R. missouriensis were as erect and green and literally carpeting the glades with their darling bright yellow petals. "Drought adapted" most certainly.


 

1 comment:

James C. Trager said...

I'm with you in avoiding the "desert-like" descriptor. The lack of winter-rain-inspired flush of annuals found in deserts is a big difference, as is the dearth of succulents in the glade.

Interestingly, the southwestern "shrub deserts" are also something of a grazing artifact, which, when not grazed or burned and very lightly grazed, can be nurtured back to a state dominated by perennial grasses.