Monday, June 5, 2017

The New Old Garden

June 5, 2017

Like knitting, beyond exotic species and new hybrids, there probably really isn’t anything completely new in gardening, only things to rediscover—AKA new-old topics. These new-old topics include lawns of mixed species, or lawn replacements, and layered green garden beds where no soil shows. 

Coastal dune prairie, with western buttercup and
early blue violets--the turf that jump-started
my new old lawn. 
Into the nineteenth and early twentieth century, lawns were closely mown or grazed turf, composed of a mix of species, including grasses, wildflowers, bulbs and sedges. In other words, any plant that could tolerate close grazing or mowing might be found growing in a turf, or low meadow. This treatment kept out or down most woody species. 

Grass-only turfs were the purview of the wealthy, who hired people to mow and weed lawns and remove the non-grass plants, often by hand. The tyranny of the grass lawn began after World War II with a shift by chemical manufacturers from wartime gases to fertilizers and pesticides. This meant that anyone could have a lush grass-only lawn, just by applying the right synthetic chemicals at the right time. 

The ‘new-old lawn’ is a mix of species of grasses and wildflowers, designed on prairie palettes of low to tall wildflowers with a grass framework. Mowing is hugely reduced. Pesticides are not used, except perhaps to remove historic exotic grasses. 

Sand-dune sedge in a bare spot
Never a fan of summer watering, lots of chemicals (including fertilizers), or excessive weeding, I began pondering the turf tyranny a few years ago. A series of dry summers meant that the grasses regularly died back over large areas of my turf. Several exotic daisies promptly made a bid for dominance, including hairy catsear, common hawkbit, dandelion and leontodon. English daisy, Viola labradorica, creeping buttercup, trailplant, strawberry and others also expanded. 

In the midst of the profusion of flowers, I found some areas of turf were still green and thriving—these were patches of sand dune sedge, Carex pansa. Dry summers did not bother them at all. Thus began my rethinking of what constitutes a lawn. I began transplanting sedge clumps into bare areas. When I weeded, I removed only the largest exotic daisies, which are nurseries for several exotic European slugs that eat many garden plants. I left the rest, including mosses, ribwort, English daisy, violet, gill-over-the-ground, and dandelion, to grow and seed around. 

Coast goldenrod, another lovely low flower for
low meadows, and a good nectar plant.

We reduced mowing from weekly to every few weeks, leaving low mown strips along flower beds and letting the lawn grow taller elsewhere. I added sea thrift. This year I began pondering bulbs, which would need to be left to grow until foliage died down. I pulled out a hedge of lilacs along the marsh to replace with tall native grasses and wildflowers—to make a belt of meadow plants that can be mown at most once a year, to keep out woody species—and will otherwise be left alone. 

There are plants I intend to exclude. Ivy, Scots broom, gorse, and several exotic blackberries grow here. If areas are never mown, these species soon run riot over everything else. When we moved to this house, most of the property was a thicket of the aforementioned species, plus wild rose, grape, honeysuckle and plum. It took us years to clear the lower slopes of the dune behind the house so we could walk completely around the house outside.
It’s a work in transition. Eventually I will have three areas that are occasionally to regularly mown, high to low. There will be more native plants, more flowers, and more habitat for insects and animals that use meadows. I already see more butterflies and bumblebees than in the past. 
Sisyrinchiums are tiny irids that do well in lawns,
just don't mow them when they are flowering.

Garden beds are undergoing the same transformation from meticulously weeded and mulched, planted with carefully grouped species, to a ‘new green garden’ with a ground cover of low growing greenery, with no bare ground at all. It’s new to early 21st century gardeners, but was the normal garden condition for centuries, beyond areas where food plants and medicinal herbs were grown.  

Fringe-cups like some shade and moist soil. 
In my garden, this means tolerating some ‘weedy’ species, and clearing areas when I plant, and only then, removing those major competitors from a few square feet of soil. It also means using slug bait or encouraging garter snakes, which eat slugs. If I lived in a low rainfall area, I might be able to justify a bare-earth garden. But with eight to ten feet of winter rain being the norm, along with dry summers, lush is the default for my garden. So my new-old garden has ground covers of sedge, oxalis, forget-me-not, mosses, and only the rapacious ‘take all the nutrients and run’ species are removed. 

It’s a new way for us to think about gardens, but it’s been around for centuries. As an ecologist the idea I like the most is that this promotes diversity in the garden, and diversity always leads to more productivity and better endurance of the ecosystem. 

Sunday, May 21, 2017

Desmostylia––Ancient Sirenians of the North Pacific

May 21, 2017

This area of southwest Washington and northwest Oregon was underwater for many millions of years. Ancient marine mammals lived here along with fishes and a wide range of invertebrates, even though we do not have fossils from every square mile to look at today. So we look around the Pacific Rim to learn about the diversity of former species.

One of the strangest animals from our watery past is Desmostylia. A chunky, stout aquatic mammal of shallow waters and shorelines, it is distantly related to modern manatees, which are Sirenians. 

Formerly much more common in geologic time, Sirenians include three living species of manatees, one dugong, and the recently extinct Steller's sea cow. Their closest living relatives are elephants and hyraxes. Fossil Sirenian species in the Desmostylia group lived from the Oligocene to the late Miocene, about 25 million years, ending about 7 mya (millions of years ago). 

By the Miocene this area was a shallow sea with several river deltas and emerging mountain ranges, and with extensive swamps along the eastern edge, near the position of the modern Cascade Range. Climate was warmer in the Miocene, tropical to subtropical, and sea level was a couple of hundred feet higher.

Desmostylia fossils, including full skeletons and partial bits of bones, teeth and skulls, have been found around the North Pacific, from the south end of Japan, through Siberia, the Aleutian Islands, Pacific Northwest, south to the south tip of Baja California. Teeth make particularly good fossils because they are hard and slow to break down. Desmostylia has interesting large molars, along with more typical mammalian tusks and canine teeth. These teeth have been described as bundles of columns, which gives them their name, from the Greek desmos (bundle) and stylos (pillar).

These mammals were aquatic, and from isotopic analysis of teeth and bones, we know that they were marine. Other marine mammal features include retracted nostrils (tightly closed when underwater), and raised eye sockets (to see better at the surface). Stocky and stout, they weighed up to 440 pounds and were about six feet long, with a heavy shovel-shaped head and large strong teeth, short strong legs, and broad feet. You can see a complete desmostylian skeleton of at the Natural History Museum of Los Angeles County. This individual lived 10 million years ago, towards the end of the Miocene. The museum has also done reconstructions of living animals, to give us an idea of what they were like.

There are no modern analogs to these mammals. For size comparisons, black bears and wild boars (feral pigs) can grow to 400 pounds or more in size. Hippopotamuses weigh up to 3,300 pounds, and live in freshwater, though some populations live in mangrove swamps. Manatees weigh up to 1,300 pounds, and live entirely in water. We could think of Desmostylia as a small hippo, in a sense, though they are not closely related.

With broad grinding molars, Desmostylians were herbivores. In marine and estuarine waters, what did they eat? Sea grasses and seaweeds, including kelps, are the mostly likely food plants. These plants live in shallow saltwater in large, dense stands. There was another powerful reason to stay in shallow water: Megalodon cruised the open waters of the world's warm oceans and seas. Desmostylia were about the right size to this huge shark to be like chicken nuggets to us.

Imagine if today 400-pound, six-feet-long marine herbivores grazed eelgrass beds in Willapa Bay. They'd jostle with the seals for haul out space, or sprawl in the marshes around the edges, and graze down the eelgrass stands at mid to high tide. Water quality might be an issue. Herbivores tend to produce a lot of poop, about five to seven times the volume, based on body size, that carnivores do. Today, hippos are one of the most dangerous animals we live around. Desmostylia might be similarly dangerous––placid until someone gets too close, and then those large teeth come into action, and oops, there's another ex-kayaker or ex-hiker. It would definitely make boating on the bay lively!

For more information, and good reconstructions of a Desmostylia, see  where a Japanese sculptor, Hirokazu Tokugawa, has done very nice reconstructions of this fascinating paleo marine mammal.