Monday, September 27, 2010

Meadows: more complex than they look

Well, the summer has come and gone, and Kaitlin’s and my research at the VINS Nature Center is winding down. My desk is piled high with plant specimens, data sheets, and leftover soil samples, and photographs virtually burst from the seams of my overstuffed hard-drive. Now is the time to examine all of our data, review some literature to help us interpret our findings, and propose management options for VINS’s meadow and pine forest. Our burning question is: How should VINS manage its meadow and pine forest to restore soil health, support plant diversity, further scientific research, educate the public, and benefit critters that hide or feed in these habitats? Based on a preliminary review of our findings, we have some ideas that we’d like to explore over the next 2 months.

Meadow Findings

At the foot of the path into the meadow is a sign asking the curious visitor, “What’s in a meadow?” When I first arrived at the Nature Center 3 months ago, my glib response was, “(yawn) Grass. More grass. Some flowers.” After 2.5 weeks of studying the vegetation in VINS’s meadow and visiting other meadows, I realized how short-sighted my perception was. Kaitlin and I discovered more than 20 wildflower species growing in the VINS meadow and even more graminoid (grass-like) species. Among the wildflowers, we saw beautiful orange butterfly milkweed, purple bergamot, three species of clover, hairy white oldfield aster, and birdsfoot trefoil. I used to think grass-like plants (sedges, grasses, and rushes) were boring, but now I have a newfound appreciation for them. Varying from yellow-greens to reds and bluish greys, carrying round or triangular stems, and bearing the tiniest flower-like structures (florets), some of which pop open when touched, these plants are marvels to behold. Take a look at the florets of a grass, sedge, or rush using a hand lens or microscope if you have the chance, and you’ll understand how clever nature is to have invented so many ways to reproduce!

The reproductive structures (floret) of a panic grass (Dichanthelium sp,)and a rush.

Kaitlin and I found that the VINS meadow has higher plant diversity than other meadows that are being actively managed (mowed). Much of this might stem from the fact that the VINS meadow was seeded with a wildflower mix about 3 years ago. But the diversity can’t solely be attributed to the wildflower mix, because we are seeing species at VINS that were not part of the wildflower mix. What else makes the VINS meadow so diverse? I think that it partly has to do with ecological succession (the process by which nature reclaims areas that have been disturbed by humans or extreme forces such as storms). Only 7 years ago, the VINS meadow was a sand/gravel pit, with exposed mineral soil at the surface. After land is cleared, when plants start to take root again, everything is fair game- anyone can move in. The hardiest plants who withstand dry soil and poor nutrients usually move in first. They start to create micro-habitats (eg. some shade, better soil) that enable other plants to move in. During early succession, the land is at its peak in plant diversity. After many years, the plant species best suited to the site will survive, and the rest will die off, leaving a smaller handful of species. Being a young meadow, the VINS meadow is in an early stage of succession.

The other two meadows we visited had been agricultural fields for 15 years or more, and they were managed every few years by mowing and/or brush hogging. It is possible that mowing and brush hogging scatter the seeds of the dominant plant species throughout a meadow, giving it a uniform look with low plant diversity. Or, perhaps they have lower diversity because they are older meadows. But how do you age a meadow when you are mowing it every few years? Does mowing set the clock back, moving the meadow to an earlier successional stage?

(From left to right: VINS meadow, Pippin meadow, Grandpa's Quarry meadow. The VINS meadow had the greatest plant species richness.

One thing we noticed when comparing the VINS meadow to the meadow by Pippin Inn was that the Pippin meadow had more structural diversity. The VINS meadow is dominated by low-lying herbaceous plants, with only a few shrubs and trees starting to grow around the periphery. The Pippin meadow is being managed for small mammal and bird habitat, so the land-owner has maintained many shrubs and crab apple trees around its periphery, which birds can perch and nest in. A large patch of raspberry shrubs also serves to attract birds when the shrubs are fruiting. Landowners who want to maintain their fields can manage their fields to support wildlife; for example, they could grow staghorn sumac to provide birds with winter fruit; they could mow early in the spring then wait 65 days to allow grassland birds to successfully nest and fledge; or they could increase the forbs: grass ratio by changing soil pH to improve pollinator habitat.

Managing the VINS Meadow

At the VINS meadow, where there is little topsoil and few soil microorganisms, we wonder what we can do to help soil development. One strategy that we might experiment with is burning, because burning can help to release nutrients from plant matter into the soil. We also wonder whether burning is an effective way to control the spread of invasive plants in the meadow. The tricky part is timing the burning so that it kills off the invasive plants after they have spent their energy reserves but before they produce seeds. We wouldn’t want to burn so early that they have a chance to regrow with more nutrients at their disposal. Also, if you have many different invasive plants, each with unique flowering times, then how do you address all of them simultaneously? Addressing them all with one burn might not be possible.

These are all important issues for VINS to consider in its future management of the meadow. In order to decide what management strategies to employ, we first need to define our management objectives. All good land management must begin with clear goals, so one can choose the best strategies to move in the direction of those goals. Do we want to increase plant diversity? What plants do we want the meadow to favor- native grasses, native wildflowers, flowers native to Vermont, or all plants, including those from Europe that have been naturalized (ie. non-native but not invasive)? What animals do we want to support- deer, grassland birds, small mammals, pollinators, or microorganisms? My next step is to outline several different management/research options and their possible effects on the meadow flora and fauna, so VINS can choose the strategies that best fulfill their management objectives. Coming up next: the results of our small mammal survey and our quest to discover the hidden potential of the pine forest (could it have been a red oak-black oak forest 300 years ago?).