There are related discussions on the forum discussing shade tolerant forages mixes and profiling a number of farms that have used various strategies to get good stuff growing after letting the sunlight in. That said, a commonly asked question in silvopasture discussions is how to suppress the initial blowup of vegetation that routinely happens following disturbances like thinning and the resulting increased sunlight levels and soil scarification.
Pasted below is recent inquiry that came via email. I'll post my my initial response, though I can think of numerous other details around this topic. I encourage those of you who see this post to add your own experiences and experiments. I feel that there is much yet to learn on how to go from woods to silvopasture on the forage side of things, especially when there's already a lot of stuff seed bank and seedling population just waiting for their chance.
the original question:
"We have a land owner that is clearing about 16 acres of forest due to invasive species choking out the soft woods in there. She is leaving many hard woods and is agreeable to creating a silvopasture area out there. She has a guy getting the stumps out and smoothing everything over and he is asking me about seed and the best next steps in that direction.
Do you recommend a good pasture mix or are there intermediate steps to take first? I'd appreciate any resources or info that could help point us in the right direction this spring. Thank you! "
I’m not aware of any applied research that has been done in this area. The general recommendation (based on our collective anecdotal experiences) for establishing forage in a freshly-thinned silvopasture is to plant a diverse mix of cool-season grasses & forbs. What will ultimately persist over time will depend on numerous variables that are hard to gauge up front (soil fertility and pH, soil type, sunlight levels at ground, interference from other plants, grazing mgmt., and weather conditions during the first season of establishment are just a few examples). For much of the Northeast, I would look for mixes that are heavy to orchardgrass.
Now for what you’re describing, just putting down a pasture mix may not be enough. Where there are already a lot of noxious species seedlings on the ground or seed in the soil seed bank, those species will probably outcompete the forage seedlings in the short-term. And since brush-hogging the weeds to maintain sunlight levels for the newly-seeded forages probably isn’t an option in most silvopasture settings, we have to think about options to suppress the initial flush of undesirable growth but then how to follow it with something better.
In full-sunlight conditions this could typically be done with an aggressive cover crop like sorghum-sudan, buckwheat, sunn hemp or some mix – especially where the soil fertility is adequate and the seed can be drilled in to the proper depth. The problem is that practically all good cover crop species (or in this case, a “smother crop”) are highly shade-intolerant so their growth may be inadequate to achieve the “outcompete the bad plants” goals if there are any significant number of trees remaining. Most of these species also need a pH of at least 5.5 and be planted to a depth of at least ½” for good establishment (again, usually not the case in a fresh silvopasture).
Consequently, I wouldn’t spend the time and money on something that isn’t likely going to establish well and shade out the herbaceous and/or woody stuff that you don’t want taking over. A lot more investigation is needed in this area, but I would default to the next best option of using a mix of coated clovers & cereal grains. The more diverse the mix, probably the better. Both of these types of forages have the potential to germinate and establish with broadcast seeding (timely moisture and degree of soil scarification – that is, the seed/soil contact potential) and will also tolerate at least light shade (yet more applied research needed to trial species & varieties). In this case, I would err on the side of caution and not skimp on the seed. I would also seize the opportunity to add in at least some “pasture mix” or orchargrass, and even stuff like buckwheat if available. The goal is to get a dense carpet of palatable plant species growing there at the onset of the growing season. It won’t keep all of the bad stuff out, but will help keep it in check initially. Afterwards, skilled and intensive grazing is going to be the most useful tool.
p.s. - I wish we had a better collective knowledge of shade-tolerance in cover crops that be broadcast seeded and that would outcompete most other woody invasive seedlings or problematic natives like ferns & brambles (Rubus spp.). I don't think the land grant researchers are going to jump on this one anytime soon, so maybe someone would like to write a SARE Farmer Grant and do some groundlaying work? :)
I expect to be able to brush hog this year to try and knock out the tall weeds.
The most helpful resource I have come across with regard to shade tolerance of cover crops is "Chart 3A: Cultural Traits" in SARE's Managing Cover Crops Profitably. Under the 'Tolerances' heading there is a column titled 'Shade.' Annual ryegrass, winter rye, berseem clover, crimson clover, medics, red clover, subterranean clover, and white clover are all listed as having 'very good' shade tolerance.