12/9 Unnatural Forest

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Five year old Spicebush, Lindera benzoin, one of hundreds planted to revive this forest’s shrub layer

Look through the boxes in your kitchen cabinet and you’ll likely see the word “natural” somewhere. Co-opted by marketers, it’s devolved into one of the most meaningless of words. The actual definition, “existing in or caused by nature; not made or caused by humankind” implies that it’s possible to draw a line between human and non-human causation (an increasingly difficult task in the age of the Anthropocene!) But if any place could be descibed as natural, it would surely be a forest, right?

This little fragment of nature most definitely stretches our notion of what is natural. Both in its past history, and our current attempts to revive native habitat, there’s a heavy hand of human causation. And some grey areas too – such as invasion by non-native plants. Is this natural or not? Though they were at one time intentionally planted, most invasive plants have spread throughout the landscape with the “natural” assistance of birds and water. Even some native plants, such as Osage orange, are only widespread because they were planted as hedges. And then there’s the subject of human transported pests such as the Emerald ash borer, which has killed at least 40% of the oldest trees in this forest.

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After Bush honeysuckle cutting, one might be hopeful that native trees and shrubs will have an opportunity. But the “seed bank” is depleted of all but honeysuckle seed. Without active suppresssion of invasives, and close planting of more desirable shrubs and trees, there will be speedy reinvasion.

If all this sounds like mere semantics, it’s not. Increasingly the forests of the world are becoming depauperate in species through logging, fragmentation, and non-native plant invasions. The link below details the increasing stresses on urban forests in particular:

https://www.thenatureofcities.com/2016/03/31/a-threatened-old-forest-tells-a-story-relevant-to-every-urban-forest/

Though “natural areas management” may sound like an oxymoron, it’s actually a strategy to keep parks and nature preserves from becoming monocultures of a few invasive plant species. Controlled burning, mowing, foliar spraying of herbicides, planting of native seed and plants are all routinely used to protect or revive the plant communities of natural areas.

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A site where Bush Honeysuckle was cut and treated with herbicide about ten years ago is now covered with many small stems of the same plant again

When I first started doing this work as a volunteer, some twenty years ago, the focus was only on invasive plant removal. Admittedly the problem was huge, since this urban fragment had been unmanaged for several decades. We always felt a sense of accomplishment after cutting and treating a large section of Bush honeysuckle or Privet. I don’t get that good feeling anymore; in fact I’d rather not remove invasive shrubs at all unless there’s a plan to replace them with sustainable native ones. For wildlife habitat, something is better than nothing.

In this little forest, for the most part, native shrubs and trees aren’t regenerating “naturally” anymore. How can this be? White-tailed deer top the list of impacts, since their browsing and trampling is vastly more damaging than any other factor. Recruitment of young trees and shrubs is also suppressed by the shady, closed canopy created by Bush honeysuckle and older trees. Finally, the impoverished seed bank only contains the seeds of what’s been growing here for the past decades. Altogether, this means the removal alone of invasive plants is a fruitless effort, doomed to failure.

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The lovely native shrub/small tree Wahoo, Euonymus atropurpureus, is very uncommon in this forest. Was it once more widespread? Delicious to deer, the only places it’s thriving are where they can’t get to it.

Planting is now the only way to recover a level of diversity that will benefit wildlife, and help prevent reinvasion by non-native plants. But what to plant? A forest with degraded soils, an impoverished seed bank, and high numbers of deer will not be able to support the kind of rich, diverse plant community that may have thrived here three hundred years ago. Common trees, shrubs, and herbaceous plants found on similar, but less damaged, sites are a good place to start.

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The young spicebush and sycamore trees in the scene above look as though they belong here, and they do – both are thriving on this moist bottomland site. But they didn’t get here on their own; they were planted as part of an Eagle Scout project about five years ago. Both are mostly “deer proof” so can survive without protection from browsing.

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All the shrubs in this landscape are Spicebush, planted as bare roots

Spicebush is one of just two native shrubs that have managed to hang on and even increase their populations as more light has become available. In a few areas, Spicebush is recruiting so abundantly from seed that small plants are competing for light and nutrients.

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these festive looking orange tags mark Spicebush that will be transplanted

Transplanting these small ones to places that have none is a great way to speed things up. Spicebush is relatively shallow rooted, and good sized shrubs can be moved with little damage to the roots.

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healthy Spicebush roots

It may seem like a paradox – unnatural intervention to help return a forest to a more natural condition. But forests are no mere collection of trees, anymore than a neighborhood is just a collection of houses. It’s the amazing variety of life a forest can support that makes the difference – and much of that life depends on a rich diversity of native plants.

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native shrubs waiting to go in the ground

This year we’ll be planting a greater variety of native shrubs than ever before, including Smooth sumac, Fragrant sumac, Bladdernut, Carolina buckthorn, Silky dogwood, American hazelnut, Elderberry, Ninebark, Serviceberry, False indigo, Wahoo, Spicebush, Coralberry, and Buttonbush. Initially, many of these will need caging to protect them from deer. But in ten or twenty years there will be a revived shrub layer, at least in some parts of the forest – and insects, birds, and other animals including deer will benefit.

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Robin enjoying Wahoo fruits

8 thoughts on “12/9 Unnatural Forest

  1. tonytomeo

    Among the redwoods that are regenerating after clear cut harvest, selective harvesting to eliminate the superfluous trunks is actually beneficial. Most trees that were cut down developed a few trunks, so that the forest is now more congested than it was naturally. Selective harvesting does more than procure lumber from an already crowded forest, but offsets some of the need for lumber from forests that have not yet been harvested.
    In our regions, there are unfortunately ‘environmentalists’ who not only want to protect the native flora, but also protect the invasive exotics.

    Liked by 1 person

    1. oneforestfragment

      In regard to the exotics, though I’ve worked to remove them for years, the results have often been disappointing. When restoration is not in the plans, and conditions don’t support the vigorous recruitment of native plants, removal can be pointless. Now that it’s winter, if I want to see birds I head to the remaining thickets of Bush honeysuckle. Adjacent areas where it’s been cut down offer no cover for wildlife. So in my opinion, it’s hard not to be conflicted about this issue. But today I willbe transplanting a lot of young Spicebush for future food and cover!

      Liked by 1 person

      1. tonytomeo

        If they were not so bad for the local environment, there are several naturalized invasive exotic specie that I would not mind in my own garden. I happen to really like Acacia dealbata, which is one of top five invasive exotics here. The bright yellow flowers in winter are SO pretty! They remind me of Southern California. Even the fragrance that so many find to be objectionable is heavenly to me. However, it saddens me to see them proliferating and invading more forest. We can never get rid of them, but we should certainly not protect them.

        Liked by 1 person

      2. oneforestfragment

        Wow – just read up on this plant and it is amazing. A global invasive thriving on disturbance in a wide range of environments, with a long life in the seed bank and also spreading by rhizomes! Do birds eat the seeds? Seems to be sketchy research on dispersal methods. Considering that it’s pretty and fragrant, the pollinators must swarm on it. I would be conflicted about this one too.

        Liked by 1 person

      3. tonytomeo

        I do not believe that birds eat the seeds, at least here. They are tiny and dry, and fall in great profusion. The small seed eating birds or quail might like them. They are sort of like the sort of seed that they eat, but much harder. I figure that they are likely designed for the birds where they are native to (sort of like the hard canna seed that are designed for parrots and macaws and such, but do not appeal to birds who can not crack them). They do happen to float away, and make drifts of seed in gullies. They really make way more seed than the need to!

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  2. conrad selle

    What is natural after two centuries of intense intervention and 12,000 years of occasional intervention before that? And now we have more deer since ever. Human hands have been on the scale for so long they are now essential to any recovery. The lost species have to be reintroduced, it is a complex work fully understood by no one.

    Liked by 1 person

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