e_moon60 (e_moon60) wrote,
e_moon60
e_moon60

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Ecotone

An ecotone is where two types of habitat meet...the zone of meeting, of change from one to another.  Grassland to woods, aquatic to terrestrial, tallgrass to shortgrass....or in human terms, from urban to suburban, from suburban to rural.  Ecotones are the messy, hard to characterize parts of ecosystems, because there's overlap, and the overlap isn't all that predictable, in detail.  Ecotones usually have more species, and offer more habitat choices to both plants and animals.

This image of an ecotone is on the south edge of our "dry woods/brush" habitat, with a fairly abrupt change to grassland, and I thought of it because of what JuliaB said--she will remember that the grass used to be bare, compacted (heavily trampled by cattle and baked into pottery-like cups and dishes--hard to walk on).  Water seeps out of the ground here after long rain events, pooling in the "dry woods swale (to the right, and pictured elsewhere in the Habitats gallery.) 

  In this image, the grassy area--mowed several times a year to about 8 inches for nonnative weed control and to preserve a shortgrass habitat near the dry woods on this side--reveals in every color variation differences in the grass and forbs now on it.  Nearer, the "beige" bits are the maturing seedheads of Texas wintergrass (speargrass); the paler cream patches are the seedheads of Texas grama (mostly), mixed with buffalograss, burrograss, curly mesquite (a grass, not a tree).  There's a single white-tridens in the shade of the trees (and more in the dry woods swale).  In the distance (too small to see, in this size, I think) there's a darker green on the right side of the image that's a little sedge where a particularly good seep comes out.  Forbs in this image include antelope horns milkweed (lower right corner of image, the white "blobs" and--almost invisible at this stage of coloring--the seedpods of the same in the lower left), Texas star, coneflower (several types), false wild garlic, greenthread, coreopsis, prairie verbena, Texas vervain, and others.  The edge of the dry woods on the right includes cedar elm with elbowbush below, prickly pear cactus, live oak with elbowbush and aromatic sumac below...the "bays" between the "peninsulas" of trees are mostly filled with cactus--prickly pear and horse crippler--and other grasses and forbs.  You can't see them in this image.

When we had the family of gray foxes, this area was a favorite place for the vixen to bring her cubs--they learned to hunt chasing grasshoppers out here.   The roadrunner likes this area too--plenty of grasshopper and lizard prey.  Both used the dry woods for cover and additional hunting area.  The coyote we have now checks this out regularly, as do the winter raptors.  Deer bed down in one particular area, though not as much since the coyote moved in to replace the foxes (they died of feline distemper.)  In winter, mowed closer than usual, this is a favorite spot for some of the winter migrants--it's sunny, often out of the wind, and there's cover nearby if needed.   Dragonflies use the tree margin for resting/sleeping cover, and fly out directly over the grassland to hunt.   Around the margins of the dry woods--the other two sides of the parallelogram that juts off the north fenceline--we've found more little microhabitats than you might expect.

Ecotone...fascinating place.
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