80AcresOnline

Since habitat management is part of wildlife management, restoration of degraded or poor habitat is part of our job as wildlife managers.   The basic concepts were laid down years ago…but the devil’s in the details, as usual.   The July 31, 2009 Science had an entire section on restoration ecology, with examples drawn from around the world showing the benefits, costs, and difficulties in this field.  Especially with the advent of global warming.

Once,  it seemed possible to restore some (small) areas to pristine conditions: no pollution, no invasive species, a full complement of the original species, once more self-sustaining.   That goal is no longer practical for most projects.

If you have an acre of land that was cleared, gardened, then abandoned, surrounded by 1000 acres of  intact virgin forest or prairie with all its wildlife in place–the best condition you could hope for–then yes, that acre can eventually melt back in and become nearly indistinguishable.  The seedstock is there, the wildlife is there, and it will come back.

But since the early days of ecological restoration, habitat has been lost faster and faster, with the growth of the human population and its demands for food, fiber, fuel, water, and living space.   Now most restorationists are working with small patches–isolated from their original assemblage (if that still exists anywhere),  that range from moderately to severely depauperate.   Besides fragmentation–which has been shown repeatedly to damage the remaining fragments just because they’re in small chunks–there’s the continuing human assault on the margins–demands for more farmland, for convenient roads, for access to resources in these fragments–there are the global changes that affect the foundational elements of life:  atmosphere, water,  soil, temperature, seasonal progression.

Everything on this planet is responsive to changes in these fundamentals (inanimate rocks as well as living plants and animals.)   Living things have adapted to their habitats–to the range of temperature and humidity,  the timing of precipitation,  the intensity and frequency of precipitation, soil types (themselves responsive to the physical and chemical properties), day-length, length and depth of cold season, length and heat maximum of hot season, the relationship between daylength and temperture, and so on.  When those change–especially when they change faster than natural selection can produce a new population adapted to the new circumstances–species either move or die.

So the restoration ecologist–or the wildlife manager trying to rebuild a healthy system for wildlife–or just preserve one–now faces new challenges.  Will the climate in 10, 20, 50 years support the trees that might be planted to replace trees logged out years ago?    Will the same animals survive?  What will the change in temperature and rainfall patterns do to the soil chemistry and microbiota?

There are no answers:  humans weren’t around the last time the planet was getting as hot as it’s getting, and the human impact on the planet–in addition to global warming–is also unique in its scale and to some extent its kind.   It is possible to make educated guesses (and so far, the best educated guesses have correctly predicted that, for instance, a movement of some species poleward and the rise in sea level.)

For a prairie restorationist in central Texas, this means looking at the structure of the prairie, not its original species list…shifting the “sourcing box” from which to obtain seedstock or replacement plants southward (for temperature) and westward (for rainfall amounts…lower and less predictable to the west.)    Our rainfall pattern, as well as the amount, has changed.    This has  severely damaged the production of annuals on which many species depend.    We’re now considering adding some species that were not original to the site, from south and west of here, and looking for new seed sources of plants that are, from sites to the south and west–plants already adapted to more heat and less water.  We’re monitoring new plant pests attacking natives (in part due to the lack of sufficient cold in winter.)

For the small amount of native brush and riparian woods, we see a grim future.   The creek was always seasonal–but it’s been dry for two years.  The older trees in the woods are dying from lack of water and younger ones are not sprouting.   Our woods, small as they are, provide the largest patch of riparian woods for miles, and a valuable resting place for migratory songbirds…if we can’t have the cottonwood, black willow, and American elm, we still might be able to maintain a vertical structure that’s useful for these migrants.    In the brush on a rocky knoll,  cedar elm and live oak were the dominant trees, but the drought has hit them hard.  This area shelters a variety of wildlife, too.

I recommend reading the articles in Science.    It was heartening (in a depressing sort of way) to find that professionals in the field had seen the same trends, and come to many of the same conclusions and plans, as we have.