The Living Seed Bank, Part 2: After the Burn
I open this post, not with a picture from the area of the restoration that was burned last fall, and is the present focus of my efforts in the seed bank quest, but a picture from across the trail to the west on a neighboring pasture I don’t own, called the Maloney 80. All those clumps of last year’s grass growth are very instructive. They are all individual crowns of porcupine grass (Heterostipa spartea). I have written about this species several times before, usually in the context of what a pain in the rear it is to seed, because of the seeds (with their spear-like awns) tendency to form almost impenetrable balls from which small groups must be laboriously plucked to fling while seeding. This is not a common component of prairie seed mixes because of the difficulties first in planting, and then in harvesting, cleaning and storing seed. I have seen a couple vendors who sell de-awned seed, but the awn helps in the seed planting itself, twisting and pushing the seed into the ground naturally while wetting and drying, so it is considered helpful to keep the awns. It is obviously an important component of native prairies here, dominating the mesic areas at the base of the hills. The picture below of my glove after seeding some porcupine grass, illustrates the difficulties the awns create:
I have many areas in my own prairies which could have been the backdrop for the opening picture, but only scattered plants in various areas of the restoration. Though seed has been spread several times I doubt there are more than a couple hundred plants scattered in the restoration. While it is not impossible to access from vendors, as always, we can run into issues with source geography, and because it is difficult to farm, it is not a cheap seed to buy. For instance, I see that I could purchase an ounce, 680 seeds, for $12.00, or about 57 seeds for a dollar, and I would have to seed it separately by hand. If I were planting big bluestem or indiangrass from the same vendor I could purchase 1050-1100 seeds for that dollar, with the added benefit that those seeds would mix well with other components of the blend that I was planting. If you were a conservation professional working with a tight budget, and limited time, which would be your choice?
I go back to the opening photo, however. How can I not plant porcupine grass, hopefully a lot of porcupine grass, if I am trying to do a prairie restoration here? To buttress this thought I saw a presentation a year ago which referenced surveys done in tallgrass prairies 150 years ago where porcupine grass, not big bluestem or indiangrass, was listed as a common dominant species. I’m in sympathy with the stance that we can’t re-create an historical prairie, and should instead focus upon achieving the ecosystem service goals we desire. However, even considering some redundancy in ecosystem services provided by the different grass species, porcupine grass seems important to me. Thus, with the open winter we just experienced, I used a significant amount of time carrying wads of entangled porcupine grass seed around the bases of the hills that were burned, plus some adjoining areas, perhaps 50 acres, and flung out many thousands of porcupine grass seeds. I did some rough math, and I may have spread 50000 seeds. In 2-3 years I will find out if I accomplished anything. How many plants would be considered a success? Can I dream of 1000? One species in the list for the seed bank. We will move on to the next example.
Above is a small groundplum milkvetch emerging from its winter doldrums. Diagonally from its lower right side you see what looks like a black pen I lost in the prairie. It is, however, the remains of the black tube that housed a seedling grown by the Native Plant Initiative at SDSU. I then placed the tube in the ground to mark it so that I could return to water and observe the seedling. Over the past two summers I have planted about 1500 seedlings of about 20 species in an attempt to leapfrog over difficulties in establishing plants by topdressing seed. If all goes well I may get another 1000 planted this year. I have centered my activities on about 10 forb species which are more difficult to access than porcupine grass. My favorite seed vendor, Prairie Moon Seeds from southeast Minnesota, has only sold groundplum in packets of 75 seeds for $3.00, or 25 seeds per dollar, the past couple years. I have spread several thousand seeds that I have gathered over the years, and the result has been 50-100 plants, not bad, but not a population sufficient for the seed bank idea. Thus, I have also transplanted about 100-150 plants started in the SDSU greenhouse. Over the past winter I spent a couple hours methodically placing individual seed into bare soil in appropriate areas. I have only a vague idea how many transplants have survived, but I hope that 30-40 did. Add in a couple more years of work with both seed and transplants and I may have several hundred to go with the several hundred living in the adjacent native prairies. With that I would feel I had something. The goal is to get a population that not only is of sufficient size for significant seed gathering, but that has some genetic depth and the ability to maintain itself for a long time going forward. How big that population needs to be is unknowable, but if I had 500 plants spread over a couple hundred acres I would feel I had something important. As each plant will often produce 20 pods with 15-20 seed per pod the restoration might be able to produce many thousands of seeds which could be shared, a pleasant thought.
I will harangue the gentle reader on just one more species to show the range of decisions that the seed bank idea has prompted, heart-leaf golden alexander (Zizea aptera), in the lower right of the photo. This is a species I see in prairies in the area, though I have not noticed one on my own prairies. It is not difficult to buy at a comparatively reasonable price, 200-250 seeds per dollar. Thus, the quandary is how much effort to add it to the seed bank. So far, the population of perhaps 50 plants in the restoration, is entirely from purchased seed. More was spread on the latest planting a year ago, so I may have more soon. It seems reasonable to me to accept some plants from purchased seed in a population from which the majority trace origin to local prairies. I am no purist, and consider those plants a valuable addition both to the prairie itself and to the genetic pool. If the genetics is unsuited to this climate they will disappear and will not contribute to seed collected here. However, if I am promoting this as a repository of locally adapted genetics which can be used in prairie restorations in the area, I would be remiss to include this as an example. Those who want to add it to their seed mixes can purchase it from a vendor. It will be the same genetics as what I would gather, as I purchased mine from such a vendor. I will change my mind if I am able to access a batch of locally sourced gathered seed (which I hope to do) and I will be happy to make efforts to put it on the list of species to increase at that time. Until then my efforts are better used elsewhere.
To sum up, efforts this winter and early spring on the 30-35 acres that were burned have included the following:
- Spreading 50# of native seed bought from my neighbor, Levi Waddell, who has a business gathering and selling native seed. This was only partially cleaned and then sold with chaff and residue, “in the dirt” as they say in the seed business. Thus, it’s not as impressive as it sounds, but it is still a helluva lot of seed. In addition I spread several pounds of cleaned seed from about 25 species from Milborn Seeds that had a source identified as within 200 miles from here. All this was spread by hand, trying to place seed in adapted sites. Millions of seeds are out there, nicely stratified after late winter snow and spring rain.
- For a select group of species for which I had less seed, mostly seed that I had gathered, I did a more careful job, placing seed individually into the soil for several wildflowers with seed which is large enough for my beat up old hands to hold and manipulate. Species I did this for include textile onion (Allium textile), oval leafed milkweed (Asclepias ovalifolia), green milkweed (Asclepias ovalifolia), groundplum milkvetch, pasqueflower (Anemone patens),prairie turnip (Pediomelum esculentum) pale spiked lobelia (Lobelia spicata), downy gentian (Gentiana puberulenta) and a couple others I am likely forgetting. Seeds of the last two species are like dust, so were spread over appropriate areas as conservatively and accurately as possible, while the rest were spread or placed as close to individually as I could manage.
- This week I will go to SDSU to check on progress of the seedlings being grown for me by NPI in the greenhouse. I plan for a significant amount, several hundred, to be planted in the burned acres.
- Finally, I am already making plans for another 30 acres to burn this fall, to do this all again.
This is the goal, a small tableau set on the little hill in the middle of the restoration. When I blew this image up, the picture showed a minimum of 12, and likely 13 or 14 wildflower species in an area of about ten square feet. Achieving such diversity and density of wildflowers everywhere in the restoration is impossible, if only because of the competitive nature of the grass crowns on more mesic sites. That’s fine, but I aspire toward greatness. The beacon is always in front of me. The concept of the seed bank provides images and a goal I will strive to reach.