We aren’t seeing it at its best, on a cold, rainy, foggy day, but in 1864 tiny Prince Edward Island was the birthplace of the Confederation of Provinces that make up Canada. It has the least amount of wild nature remaining of any of the provinces, and it grows 1/3 of the potato crop of Canada, but its primary claim to fame is as home to fictional Anne of Green Gables. On a sunny day, biking through the pastoral landscape on the Confederation Trail would have been ideal. Instead we tried to escape the rain by following a forest path through Victoria Park at the western end of Charlottetown.
This should be called the year of the fantastic nut crop: acorns by the ton, walnuts carpeting the lawn, and buckeyes remaining unharvested because there is a food surplus in the backyard like never before.
Why is this happening? I don’t remember there being great spring weather; oh wait, I was in the UK during spring. The summer was the usual blend of hot and humid interspersed with cold and rainy, so it must have been perfect for growing a huge nut crop. But why have all the oak trees in the backyard gone crazy with acorn production?
We are experiencing a “mast year” in oak tree production of acorns, which happens irregularly, every two to five to seven years. And it’s happening in not just one species of oak, but simultaneously in the three most common Minnesota oak species — the northern pin oak, the northern red oak, and the bur oak.
In a recent post (September 12), I discussed how trees “talk” to each other, and this synchronous boom production of acorns is a good example of the result of that communication, which can occur not only locally within a forest, but over broad distances. Basically, mast production of acorns is the trees’ combined strategy of satiating the acorn consumers so that the leftovers can develop into seedlings.
The oaks must have been talking to the walnuts in the backyard as well, and the squirrels are just not able to keep up with the bounties of this fall harvest.
The perfect response to this enormous fall bounty — “stop, I’m full already”.
My apple trees are well synchronized with each other, so I have bumper crops of all 4 trees in alternate years. Of course I want them to flower at the same time, so there is ample pollen for cross pollination of the different varieties. However, this year, the trees were unusually productive…
Is it just coincidence that these trees are so well synchronized or do they somehow communicate with each other about their status? A quick google search led me to a terrific article in Smithsonian magazine from March 2018 on this very question.
One way that trees, and plants in general, can communicate with each other is by way of the mutualistic fungi that entwine their combined roots.
The fungal strands search out and transport various nutrients that the plants need (nitrogen, calcium, phosphorus, magnesium, etc.) from the soil to the rootlets, and the trees pass photosynthesized sugars from the rootlets to the fungi in a very cooperative relationship. But it goes beyond just the interaction between plant and fungi.
Research by Suzanne Simard (in a very interesting TED talk) has shown that individual trees in the forest are connected in a dense underground web of overlapping and intermingling roots and fungal associations, and this web consists not only of a “mother tree” and its seedlings, but trees of all ages of other species as well. Through these connections trees exchange carbon and other nutrients, paying a small tax to the fungi along the way.
Not only are trees sharing resources in this busy underground network, but they are communicating with each other through secretion of plant hormones and volatile secondary compounds as well. For example, Giraffes that munch on the leaves of one acacia tree will stimulate the production of distasteful tannins not only in the other leaves of that tree, but in its acacia neighbors as well. In fact giraffes have learned to forage on the acacias that are downwind in a clump of trees to avoid this kind of response to the volatile chemicals released by the injured tree.
This kind of changes the way we look at forests, or even small patches of prairie, or garden plants, or shrubs growing together in our backyards. These plants aren’t as much competitors as they are collaborators, existing side by side, in a mutual quest for light, water, and nutrients. We could learn a lot from plants about cooperative existence!
Rothiemurchas forest in the Cairngorm National Park of Scotland was once the center of the great 12th century Caledonian pine forest, and some of its patriarchal trees may still stand.
We found some new (to us) birds here, as well as some familiar ones, but one of the surprises was all the red squirrels in this part of the forest. They are about the size of the North American gray squirrel, but with much bushier tails, and ear tufts. In many places these native squirrels have been displaced by the introduced gray squirrels.
Although most of the birds were found high in the tree tops, a few cooperated by flying in close.
The California Bay tree, also known as the California Bay Laurel or California Laurel, and a host of other names, is one of its kind, the only species in its own genus, and quite an interesting plant. Bay trees are part of the coastal forest and unique to the California floristic province.
Their leaves are more pungent than the Mediterranean bay used in cooking. My husband once stuffed a chicken with bay laurel leaves before cooking it on a Boy Scout camping trip and found it completely inedible.
Like some other coastal tree species, California bay have a swollen base of root crown called lignotuber which protects delicate buds that sprout when the central trunk has been damaged.
The resultant growth of multiple stems emerging from the root crown makes this forest look like a dense jungle.
What a difference the microclimate of this forest makes. We wore our jackets while hiking through the dark, shady north facing laurel forest, and worked up a sweat climbing the sun-exposed hills of oak forest.
The Amur Maple forest has once again reached its full fall splendor.
Dense thickets of Amur Maple crowd out and shade out natives that might grow there — really the only thing this species has going for it (in my opinion) is the brilliant color display of its fall leaves. The ground cover beneath the trees looks like a collection of fallen leaves, but on closer inspection, it seems to be a mini-forest of Amur Maple seedlings, ready to bolt up as soon as a light gap appears in the forest overhead.
Well, not so much the color of the river per se, but it was the color along the river last week in Wisconsin and Michigan during the peak of the fall color show that was impressive. Some examples, seen between rain showers:
We know that warm days and cool nights of fall stimulate plants to break down their chlorophyll, unmasking all the xanthophyll and carotene photo pigments in the leaves, and those changes in leaf metabolism produce the yellow, orange, and red colors. I have written more about the chemistry of leaf color change earlier — (“you know it’s fall when…”). But what accounts for the synchronous color changes of rural northern hardwood forests, compared to the more prolonged sequential color changes we see in urban landscapes?
Lots of factors might be responsible: urban areas are generally warmer with a less homogeneous climate than surrounding open countryside; plants in a natural forest most likely respond to climatic changes in similar ways, whereas planted urban trees, often non-native, adapt to a mixture of environmental cues with different schedules for leaf fall. Leaves might change color more slowly and stay on trees longer in the urban environment simply because temperature and moisture conditions there are so different from the surrounding countryside.
I’ve always wanted to visit the Porcupine Mountains in northwestern Michigan, and fall is the perfect time to take in the color change in the forest, as well as the dramatic cliffs in the park. Rising to a peak of just under 2,000 feet and lining the southeastern shore of Lake Superior, they provide great views of the most extensive old growth of northern hardwood forest west of the Adirondack forest in New York.
One of the star attractions of the park is Lake of the Clouds, so named for its mirror reflection of the sky. But equally impressive are the sheer cliffs of ancient volcanic rocks that form a long escarpment on the northern side of the park. These are the exposed remnants of the volcanic action that formed the mid-continent rift that runs from western Lake Superior all the way down to Kansas.
On the western edge of the park, the Presque Isle river churns through volcanic deposits scrubbing out holes and undercutting cliffs.
The river is lined with hemlock forest where trees are so close together, barely any light makes it to the forest floor.
Well-marked trails and wonderful scenery make this an exceptional place to visit, especially during the peak of the fall color season.
It might sound like this is about a fashionable department store, but beach ridges and the shallow, watery swales between them are natural features of the Great Lakes shorelines. We hiked at one example of this complex ecosystem at the Ridges Sanctuary in Bailey’s Harbor on the eastern side of the Door peninsula.
Ridges and swales are most likely to develop where coastal land is uplifted or where lake levels fall, which is probably what has been happening here in the past 10,000 years since the last glacial recession. Sediments are deposited with gentle wave action against the shoreline in a protected harbor, leaving behind a low hill of sand and gravel in which hearty colonists establish themselves.
The variation in environment from dry to wet, or coastal to inland makes this an extremely diverse ecosystem, home to more than 500 species of plants, 60 some species of birds, and more than a dozen mammals.
The Ridges Sanctuary was founded in 1937, becoming Wisconsin’s first land trust, designed to protect the state’s most biologically diverse ecosystem.