by Stephen Packard
[Editor’s note: For four decades Stephen Packard has been restoring a wide variety of sites. His comments are notable, and blogposts are great. I had asked Stephen for advice. On a new acquisition, we are about to clear very dense brush on an upland savanna. The habitat currently has few native plants with the main ground cover being exposed soil. Should we start adding seed immediately? With Stephen’s permission I share his response – Bill K ]
The studies I’ve seen suggest that there’s little “seed bank” in badly degraded prairies, savannas, and woodlands. In some marshes, there seems to be a helpful seedbank.
I’ve seen a lot of people try to rely on the seedbank, with dismal results.
We initially waited for “the seed bank to express itself” in some areas, and it just opened the ground to a lot of thuggish or invasive species that – far from reconstituting a natural ecosystem – burned poorly and allowed invasive brush to take over again.
I don’t seem to have any blog posts on quite that question. I do have this one:
It’s about how well it worked in a woodland (lots of leaf litter) to plant into dense leaves without a burn. It didn’t work.
Also of possible interest is this overall summary of some Somme Prairie Grove efforts, starting in 1979. Broadcasting seed into former pasture worked best. On the other hand, this experiment is very different from the site you describe – in that it included many small remnants of good or high quality and more than 250 species of savanna plants including many conservative and even endangered ones.
It includes the following:
Question: How well will a damaged ecosystem recover, and how much apparently missing biodiversity will just come back in response to remedial care?
Answer: Very few plant species that were not on our initial inventories came back from the seed bank or otherwise appeared. This was disappointing. On the other hand, many conservative species that had been present in small numbers increased dramatically. A few species (notably the endangered Bicknell’s geranium) did seem to emerge in response to the burns.
I suppose a wide variety of experiments are valuable. In more recent efforts I’ve been involved with, we’ve started seeding at the beginning, to get the jump on the thugs like tall goldenrod, to some degree.
Given the charged climate, rain acidity, nitrogen deposition, fragmentation, etc. – it seems to make less and less sense to limit seeding to species that were exactly on that site. We go farther south for seed, but not north. We imagine that the community of species that now best suit the site may be different to some degree from what was there 200 or 500 years ago.
Our goal seems more often to be to restore a high quality, diverse community, and then let the species sort out the rest.
Hope this is helpful.