Natural Communities

All forest is not the same. These trees are part of a unique natural community.

Looking at plants as communities from a design point of view is cool but it’s also cool to look at plants as they fit into natural communities. I’ve often wondered what kind of natural community my garden belonged to before it was timbered, farmed and then developed. I know it was forest but is there more to a forest than one would think? The answer is yes, there is more and I’ve recently discovered a website that explains just such a place known as Rock Creek Park, not more than a mile away from my garden. The website, a collaboration between NatureServe and the Research Learning Alliance of the National Park Service’s National Capital Region, examines 8 different natural communities within Rock Creek Park,  the oldest and largest urban national park in the U.S.

As I read about some of these communities it occurred to me my own garden may have been one of them at one time. It seems natural communities develop over time due to natural and unnatural forces. These forces such as rain, wind, sun, human development among others form small pockets of distinct areas with distinct landforms, soil, plants and animals. And underneath it all is the bedrock, often the main compositional ingredient.

The other day I went walking in Rock Creek Park to see if I could find and see the difference between some of these communities and I have to say while it was a bit of a challenge, I did notice a few.

Mesic Mixed Hardwood Forest can be found on rolling landscapes where the soil is loamy (made mostly of clay, sand and silt with a little organic matter)

The most wide ranging one is the Mesic Mixed Hardwood Forest. It can usually be found on rolling landscapes of the Piedmont and Coastal Plain of Virginia, Maryland, New York and New Jersey. It also has a wide range of vegetation such as American beech, red, white, black and scarlet oak, Christmas fern, sweetgum, red maple, blackgum, flowering dogwood, American holly, pawpaw and mapleleaf viburnum. It has a well-drained and mesic soil. I have a pretty good idea my garden was once part of this community.

A box-elder, part of the Tuliptree Small-Stream Floodplain Forest community.
The rich soil of the Tuliptree Small-Stream Floodplain Forest supports many herbaceous plants such as this pretty ground cover.

A very different community is the Tuliptree Small-Stream Floodplain Forest. It usually lies along floodplains of small streams such as Rock Creek. The rich soil here, made up of sediment that gets carried down the creek from upstream, supports plants like the tuliptree, red maple, box-elder, American sycamore and American hornbeam. Because the soil is often disturbed by flooding and human use, it also can be a haven for non-native plants as well as many other native plants. I heard lots of birds with unique, buzzy noises here. I’m guessing they were smaller warblers and such.

A white oak and mountain laurel in a Oak – Beech / Heath Forest community.

Another community I walked through was the Oak Beech Heath Forest. It usually can be found on steep slopes above streams and rivers where acidic and often rocky soil is perfect for plants such as mountain laurel, American beech, chestnut and white oak as well as blueberry and black huckleberry.

Although it takes a bit of exploring to get the idea, the website has a wealth of information about geology and ecology that I can apply to many things about my garden. In fact, I’ve found I’ve started looking at plants in a new way. Not as plants but as parts of communities, something that may be a big step towards ecological improvement. Not just for me but for all of us.

A Park and Mysterious Sounds in the Night

rock-creek

I live on the edge of a bustling downtown equipped with a mall, movie theaters, office buildings, city buses, traffic and people, lots of people, but no more than a mile from my house is an extraordinary expanse of old growth forest you can actually get lost in and not hear a car. You may see some people (usually with dogs) and maybe once, if you’re lucky, hear a barred owl. I kind of just discovered this place and now I go there as much as I can venturing as far off the main trails as possible onto narrow trails dangerously lined with poison ivy. It’s the kind of place you don’t see even in the wild, the places you drive for hours to get to. Trees just aren’t that big anymore.

The trees in this park aren’t just tulip poplars. Oaks, beech, elm and ash with trunks I can’t wrap my arms around, tower majestically above. I love to get to that spot where the landscape as far as I can see in all directions is forest and it’s not hard for me to imagine that long ago this is how it was everywhere. I still can’t believe this is only a mile from the very urban place I live in.

The park’s name is Rock Creek Park and as a matter of fact, I went walking in it just yesterday and heard what I’m pretty sure were wood frogs. They can be heard here.  Wood frogs are the most cold tolerant of all the North American frogs and can be found in the Arctic Circle. They are also the first frogs to breed every year. They live in woodlands and lay their eggs in vernal pools which are basically puddles that dry up in the summer. That means the tadpoles must turn into frogs before the pools dry up. Wood frogs aren’t the only amphibian to depend on vernal pools.

I’ve always loved night noises and never really cared what was making them until recently when I started watching a spooky old soap opera from the 70’s called Dark Shadows. In its many brilliant night scenes full of styrofoam tombstones, bats dangling from strings and plastic plant life, there are night sounds including one one that I knew I’d heard somewhere before. Where had I heard that sound and who was making it? While searching the internet for the mysterious sound in Rock Creek, I stumbled upon the mating call of a toad. That was it! I’d been hearing it all my life and never even had a clue.

Frog and toad populations, especially in urban areas like mine are in serious decline. Half are gone in nearby Arlington County. Because their bodies absorb toxins through their skin as well as from the plant and animal life they eat, they are extremely sensitive to environmental changes. On the flip side, their reemergence is a sign of environmental improvements.

Frogs and toads are great assets in the garden, eating all kinds of pests such as slugs, caterpillars, grasshoppers and mosquitoes and of course what do many insects love and depend on? Native plants. I figure if these animals live only a mile away, maybe there’s a chance they will find their way to my garden. Then again maybe a move to downtown wouldn’t be such a good idea. At any rate I’m glad to know there’s a place nearby where they can live and meanwhile, I’ll be listening for their calls.

If you are interested in hearing an amazing orchestra of hundreds of frogs and toads visit Merchant Millpond State Park  in the spring, just before nightfall.

BTi and The Mosquito Dilemma

mosquito

Unless you’re a bat or a dragonfly, July and August and even September are not comfortable times to be in my garden. When these months hit I wear a suit of long pants, high socks a long sleeve shirt and a heavy dousing of bug repellent. But no sooner am I pulling up that quackgrass, when I feel the itch. First one, then another, then then the whole swarm catches on to the delicious snack. Me.

The main advice about this problem is remove anything that collects even the tiniest amounts of water which includes gutters, rain barrels, containers, etc. The other advice is to use BTi or Bacillus thuringiensis subspecies israelensis, a natural bacterium found in soils and thought to only affect mosquito, black fly and fungus gnat larvae. At least this is what the EPA says as well as many other sources but a study was done in 2010 involving house martins that concluded evidence of effects further up the food chain. The study found the breeding success of house martins was significantly less in areas treated with BTi than in areas untreated with BTi. Loss of mosquitoes, the birds preferred food source, was found to be the cause.

I’ve heard Mike McGrath, the gardening guru from Philly talk about using BTi dunks to make mosquito killing traps. That sounded great at the time. But as it’s now winter and I’m not out in the hot sun getting massacred, I’m thinking that maybe the mosquitoes are here for a reason. Maybe instead of trying to completely annihilate them as we humans like to do with anything that “bugs” us or our stuff, maybe we should think about these problems from more of an ecological perspective.

It may be better to think more in terms of balance rather than control, coexist rather than divide, proact rather than react. Maybe we get ourselves so focused on the problem we don’t see the solution. Inviting animals and invertebrates that eat mosquitoes might be the best solution we have. Bat houses and mosquitoes invite bats. Water and mosquitoes invite dragonflies, frogs and birds. Bats, dragonflies, frogs and birds mean a stronger ecological system. A strong ecological system means a better chance of long term survival for us all.

I would say I probably have too many mosquitoes and this year I’m going to work on that but I’m not going to go extermination crazy. I’ll use small pieces of BTi mosquito dunks in my rain barrels only because it’s the only way of mosquito proofing them. When mosquitoes are bad, I’ll stop using cardboard that collects water and refresh bird baths twice a week. And I’ll wear my mosquito protection suit. While it’s not exactly the best case scenario for me (at the moment), it’s the best case scenario for ecology and that, I think, is the best case scenario.