Investigation question: Using only the clues in twelve undated field notes, can you put the return of life in two places hit by the 1980 Mount St. Helens eruption in order, and explain why one place recovered so much faster than the other?
Field-note cards (cut apart)
1 Card ARain has cut small gullies through the gray ash layer, and the old brown forest soil shows in their walls. Huckleberry and other shrubs have grown back from roots that survived underground and now form clumps about waist high. Small fir trees that lived through the blast under a snowbank are putting out new upward shoots above the ash.
2 Card BMany lupine patches have grown and run together into wide mats. In other patches most of the plants are brown and dead: I found moth caterpillars tunneling inside the roots and feeding on the plants. Grasses and other wildflowers are scattered among the lupines, and elk hoofprints and droppings cross the plain.
3 Card CTrucks are hauling fallen logs out of this valley, and crews are planting young Douglas-fir and noble fir seedlings in rows, digging each hole down through the ash to the old soil. Note to self: this land is outside the protected area, so its owners can log and replant it.
4 Card DGray pumice and ash stretch in every direction. I dug a pit 50 cm deep and found only more pumice: no old soil, no roots, no buried seeds. After rain, steam hisses from a few pits, so the deposit is still hot underneath. My insect traps caught many beetles, flies and spiders that had blown in on the wind; most were dead or dying.
5 Card EA dense young forest of fir and hemlock now shades many slopes, and the ground under it is cool and dim. The giant trees that fell long ago have gone soft and crumbly, and mosses, ferns and mushrooms grow on them. Woodpeckers drum on dead trees that are still standing.
6 Card FOne lupine plant is blooming on the open pumice, with a ring of tiny lupine seedlings around it. I cannot see another plant for kilometers. Background: lupines are legumes. Bacteria living in small bumps on their roots turn nitrogen gas from the air into nutrients the plant can use, so a lupine can grow where the ground has almost no nitrogen.
7 Card GHuge trees lie flat in rows, most pointing away from the volcano, under a gray layer of ash and broken rock. When I dig through it, I reach the old brown forest soil, still full of roots. On a steep slope that was still under snow on the day of the eruption, small fir trees are bent over, but their needles are green.
8 Card HThickets of willow and alder along the streams are now well over my head. A few young conifers grow in sheltered spots, far apart from one another. Under the meadow plants there is a thin layer of dark, crumbly soil on top of the pumice. From a ridge, the plain is a patchwork of green and gray; there is still no forest.
9 Card IFireweed and bracken fern shoots are pushing up through cracks in the ash. When I dig beside them, I find their roots and underground stems running down into the old soil. Dark mounds of soil mixed with ash dot the gray surface where pocket gophers have tunneled up from below, and tiny seedlings are sprouting on some of the mounds.
10 Card JLupines now grow in scattered patches a few meters wide. Inside a patch, the pumice is darker and holds dead lupine leaves and bits of litter blown in by the wind. Soil tests show more nitrogen inside the patches than in the bare pumice between them. Seedlings of other plants, such as fireweed, pearly everlasting and grasses, sprout far more often inside the patches, especially where old lupines have died, than outside them.
11 Card KYoung conifers taller than I am grow in patches between the fallen logs, and shrubs shade much of the ground. The fallen logs are starting to rot; moss and small mushrooms grow on their bark. Songbirds sing from the young trees.
12 Card LSmall streams fed by springs cross the plain, and their banks are lined with willow and alder shrubs, a few already taller than I am. I counted tadpoles in a shallow pond. Between the streams, meadows of lupine, grasses and wildflowers alternate with wide gray patches of bare pumice.
Simulated teaching dataset. The numbers are invented; the pattern, with cover returning far faster in the blowdown zone, matches what ecologists described.