Friday, November 7, 2014

A new savanna outside College Station, TX

This savanna made possible by heavy equipment.
College Station has a new oak savanna, thanks to a creative restoration effort by a local landowner and a TPWD biologist. Originally, the landowner had approached TPWD with the thought of putting his land back to native grasses. He was getting older, and he wanted his holdings to look like native prairie again. Most land in the area is dominated by the commonly over-seeded nonnatives: bahia grass, bermuda grass, johnson grass, and various old-world bluestems.

Great purple hairstreak nectaring on old frostweed
On this particular site, however, the problem was thick brush, especially yaupon holly, choking out the native post-oak's understory like a green wall. Inspired by the compensation offered from the frackers who owned the mineral rights and were coming in to build a new pad on-site, the landowner instead negotiated for hours with a bulldozer. After clearing the brush he over-seeded with the native grasses recommended by TPWD.

The site looked great, exceptionally so for a year '0' restoration. Many of the seeded native grasses have established, as have some pioneering flowering plants. Beautyberry and pokeweed were most abundant. I also spotted a few tendrils of maypop, frostweed, smartweed, and some other species.

closer: great purple hairstreak
Frostweed (Verbesina virginica) is a wonderful plant, an important late-season butterfly resource with a unique attribute: during the first freeze, its sap is extruded through the stem where it solidifies into curling 'ice sculptures', similar in appearance to the icy frost flowers that burst up through the ground in colder climates.

A gorgeous great purple hairstreak was investigating the few remaining blossoms on a tall frostweed in the center of the savanna. He (?) was shimmying the tails on his hindwings enticingly- evidently a behavioral adaptation to encourage birds to take a nip there instead of places where they could cause real damage. Interestingly, great purple hairstreak larvae eat only broad-leaved mistletoe. I didn't think to examine the treetops for these arboreal parasitic plants, but I can imagine that a savanna with an understory of rich nectar sources and an overstory hosting their larval food plant would be a good place to make a living as a butterfly.

I think most people find savannas quite aesthetically pleasing, and I hope this site stays lovely, propelled forward by a solid start.

Beautyberry lit by a patch of sun in the understory
Lady's tresses, Spiranthes spp.
The landowner's other sites were not so easy to restore. Simply making room for other plants in a matrix of the aggressive non-natives is no small undertaking. Repeat applications of glyphosate or imazapyr are often needed to even make a dent in the exotic grasses. This sort of broadcast chemical application makes my little heart sad, but sometimes it is a necessary evil. Notably, in the case of this landowner's other holdings, applications of herbicides had successfully suppressed the nonnative grasses and released the native grasses that had been holding out all along. I do still worry about the broadleaf plant community under these circumstances. However, a lone lady's tresses orchid had managed to put up a bloom in the middle of a sprayed patch. If an orchid, a representative of a characteristically delicate family, can push through, then maybe there is still hope for the others.

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