Familiar orientation north to south
Years ago Greg and I were driving up to his father’s cabin in the mountains of eastern Humboldt county California. Its located at 4700′ elevation on Horse Mountain in the higher ridges of the Northern Coast Range. As we wound up the mountain on a scary one lane road a familiar feeling over came me. At about 3500′ the composition of the flora changed and I was stunned. The forest was primarily composed of Douglas Fir (Pseudotsuga menziesii), White Oak (Quercus garryana) and California Black Oak (Quercus kellogii). Interspersed occasionally were Ponderosa pine and Western Dogwood, and the understory was familiar Amelanchier (Serviceberry) and Western Viburnum (Viburnum occidentalis). It struck me because that was nearly the exact composition of forest that I grew up in SW of Eugene in Western Oregon. That was at 500′ elevation but here 375 miles to the south it had shifted according to the climate at 3500′. This shows how our native plants orient themselves according to elevation from north to south. Half of Southern Oregon is clearly in the California Floristic Provence and that same composition of plants (with the inclusion of others) can be found higher and higher as you move south. The same zone can be located in the middle and then higher elevations of the Sierra Nevada inland.
You of course are familiar with the migration of animals. Did you know that plants migrate too? In college I studied this movement according to the changing climate from the ice ages to the interstadial warm period (between the ice ages) and then back as cooling took hold again. You can re-create the climate by collecting the mud of lake bottoms, washing it and isolating the pollen. The remains are un-decomposed in the anaerobic conditions with the specific characteristic of each species retained. You can then carbon date the pollen and reconstruct the taxa assemblage (plant composition) and relate that to an existing analog and recreate a picture of a past climate. For instance during the height of the ice age 11,000 years ago the Willamette Valley was very different. Pollen shows that the predominant trees were Picea englemanii , (Engelmann’s Spruce), Tsuga mertensiana (Mountain Hemlock) , Pinus contorta (Lodgepole Pine) and Aspen. Currently that assemblage is located just to the drier east of the Cascade crest at approximately 4500′. The climate was not just much, much colder it was drier as well. I won’t go into the weather /climate that accounted for that but suffice it to say things were quite different from today. As the climate warmed the plants changed and followed. Low elevations species surged north and up and higher, colder adapted species were relegated to the higher elevations. Up until 3000 years ago we had been (HAVE) been getting cooler going into another cold period and flora was beginning to switch its migration. We all know now that we have changed things and things WILL be drastically different in the next few hundred years.
We’ve gotten in the way
If humans hadn’t interfered- and gotten our big ass selves in the way the climate and plants would have adjusted and moved according to a much slower pace. Temperature changes of 1ºC per thousand years gives plants some time to reorient. Now we are looking at 3-5ºC warming in the next 60 years. That far outpaces the natural progression of plants and not to mention we are in the way cutting off corridors of migration. Dentist offices, farming, strip clubs are all in the way. So, without giving a bigger guilt trip I prefer to look at things in a more pragmatic way. Our native plants need our help. There’s no way they can adjust to the time frame we’ve thrust upon them and the results could be disastrous.
Diversity is the issue
So, we have national parks you say? Well yes but the climate will change and the plants will not have a reasonable amount of time let alone a corridor to move. This is where we need to step in. There are a select few species that have already been used – repeatedly, over and over again in our landscapes. Natives that make people feel good about spouting off sound bites that they are using “native plants”. And this makes everyone feel better. What has happened is two fold. First the easiest to grow and most adaptable natives have come to dominate the field and what we have now is a great lack of diversity. Native plant ghettos as I call them. Where once in a particular location there was the diversity of scores of species now – for instance in the parking lot at Target there are four native species represented. What are they? Well, usually Ribes sanguineum, (Flowering Currant), Cornus sericea (Red twig Dogwood) Myrica californica (Pacific Waxmyrtle) and the most abused Mahonia aquifolium our ubiquitous state flower. The plants may be native but diversity is slashed. Native annuals, perennials, shrubs, trees …..all eliminated for three or four species and it makes people feel good. If we want to maintain our native diversity this is going to have to change.
The hills are alive
So at Xera we have chosen not to exclude those few repeated species- there is absolutely nothing wrong with them but we’ve engaged on a path of the details that are getting left behind. We want to reconstruct the diversity that was present before settlement and we want to expand peoples ideas about how plants move and need our help. And- as a gardener you have never been to visit our amazing native plants in the wild you are missing a great deal of the enjoyment of gardening. Much like viewing animals on a safari there is a great joy in viewing our native plants in their habitat. Not only does it swell your appreciation for beauty it teaches you to view the whole picture. Combinations, soils, aspects, all come in to play and can give us great ideas about how to construct plant communities in our own gardens. And though there is a great vogue for the latest plant from Taiwan or Szechuan I can tell you that we have thousands of our own native treasures that should be discovered as garden plants and they need our help.
Its the details
We already have a climate that supports an immense wealth of diversity but we need to be stewards and use these plants as they are adapted. One thing that must happen to establish a native community is to protect those plants from invasive exotics that overwhelm and stress our native composition. Next, we need to adapt our aesthetics as gardeners to the natural ebb and flow of wildflowers and seasonal interest. Then, we must provide these protected communities with the little bit of care to protect them. And its not that hard. They are already adapted to our soils and rainfall patterns. Inclusion in our gardens is just one way to ensure that they live on and that diversity is preserved.
Let the sun shine in
So, take a little time to go out and visit our native plants. And its not a trek either -less than two hours into the Gorge in June sees hillsides replete in blue Ceanothus, with pink nootka Roses and the penetrating perfume of Philadelphus (Mock Orange). Underneath are wildflowers such as Alliums, Sidalceas, Lomatias, even nifty native clovers that make enchanting garden plants. Thats just one of a number of places that deserve a visit. Saddle Mountain in the Coast Range, The Rough and Ready Botanical Wayside in the Illinois Valley of Southern Oregon. Visit and come away with some of the best garden ideas that are applicable to our climate and region. These plants are going to need our help. We must honor them and diversity. As gardeners its our job.