Diversity and Ecology

[shadesofmauve]

 I've always been attracted to diversity, or, more accurately, repelled by homogeneity. On the net that discussion usually centers around human diversity, but I noticed it first in the physical world* -- that manicured lawns, tracts of suburbia, and mass-planted forests of baby doug fir all feel dead to me. Or perhaps deadly. Deadly boring. I like neighborhoods where the houses were clearly built at different times by different people, and forests where shafts of light strike through the gaps left by the wind-deaths of mature trees, gilding the saplings and understory in the clearing. 

It shouldn't be surprising, then, that reading books on ecology and biodiversity tends to be less enlightening and more "Yes! I knew it!" confirmation. It just seems obvious that the scrubby, 'weedy' prairie is alive and the lawn isn't (in an ecological sense). When I was a kid I spent a lot of time camping in the Olympics, often on timber company land, and saw first-hand the difference between a mature forest, the awful scars of a clear-cut, and the deadly-dull sameness of a commercial reforestation project. 

(It is painfully amusing to me that two of the things that fill me with revulsion -- one-era suburban tract housing and homogeneous commercial 'forests' -- are so intimately related. This is most brilliantly illustrated with the local 'planned community' of DuPont, which started as a bold move in vertical integration by Weyerhauser. If there isn't enough market for your stand of trees, build houses out of them on the spot and sell those!).

I realize that in a lot of places, my extreme aesthetic dislike of homogeneity is nothing more than a meaningless quirk. There can be all sorts of interesting people hiding behind the same-y walls of the tract houses, and there's no ethical or important meaning to the fact that one person decorates her house on a theme and I tend to eccentric. But in the natural world, it matters. It matters so much.

One of the core concepts of ecology is that everything in an evolved environment is interrelated. We tend to illustrate that by pointing to simple chains (the x eats the y eats the z), because it's easier to grasp, but the actual ecosystem is far more complicated than that. There's a web of interconnections that makes things more interesting, more diverse, and more robust. More alive.

(Yup. Environments with more biodiversity tend to have more biomass. They are actually more alive).

Biodiversity is the real reason why I'm adamant about growing native plants and removing invasives. Native plants are part of the incredibly complex web; non-native invasives aren't just external to the web, they actively destroy it. When english ivy (one of the big problems here) took root in the greenbelt near my house, oh-so-many moons ago, it first smothered the small forest-floor perennials, then started climbing (and choking) the trees. It can do this because nothing eats it -- ivy is worthless to any of the critters here. The only thing it provides is habitat for rats -- the norwegian rats that are another human-transported pest-species. It has such shallow roots that it actually contributes to soil erosion, as well -- disturbance can tear off a mat of it, taking with it the upper layer of soil, where a deeper-rooted plant would help hold the soil. This may seem unimportant in the northwest, with our deep loam -- it's never going to be a dustbowl situation -- but we also have steep hillsides leading down to water, and hillsides can and will slide right down into the drink. Things that eat the native plants and don't eat the ivy are bugs. Other things eat them, obviously -- deer, for instance -- but if you were to count species, the vast majority of things feeding on those plants are insects, and the vast majority of insect species are super picky about what they eat. Insects are the nice, high density source of protein for other insects, mammals, and nesting birds, and so switching fifty species of native plant for one patch of ivy ripples on up the web.

English Ivy is one example out of many (one very close to me, in the strictest sense; I fight a continual battle against it in my yarden), but the key thing it demonstrates so well holds true if you look at other patches where an invasive plant has taken hold. Those places are homogeneous. They might contain a small handful of species, often other invasives -- like the unholy alliance of ivy and blackberry in yarden, or lawn grasses and the lawn pest Japanese beetles -- but only a handful.

Compared to a thriving ecosystem, they're very homogeneous. Dead, and deadly.

 

*For what it's worth, I do get the same almost-claustrophobic omg-have-to-get-out feeling when confronted with extreme human homogeneity, too, but since my biggest experience of that was at a really fancy golf course restaurant filled entirely with wealthy white men who all cut their hair exactly the same way, it's a bit hard to tell if it was just 'homogeneity' or, as my dad put it, being in the presence of 'the people who run your world.' Freaking terrifying, that was.