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A secret reservoir of bees in the forest

Because I live adjacent to a 91,650-acre state forest, I’m always interested in bees that might dwell in the woods. On hikes through the trees, I seldom see any bees except for an occasional bumble-sounding bee that circles me as I walk. Around it goes, getting louder and then receding, over and over. Its behavior is so predictable, I could swear it’s the same individual every year.

The Capitol State Forest is managed for timber production, and the money made from sales goes primarily to education within the state. Like many managed forestlands, the area is divided into segments. Each year, some segments are logged while the rest are allowed to grow. In newly logged areas the slash is piled into great mounds, Douglas-fir seedlings are planted, and other growth is sprayed with herbicide until the seedlings are large enough to compete on their own.

In 25 years, I’ve seen a number of sections harvested and replanted. Regrowth seems slow in the beginning, but once the seedlings get started, they shoot up like moon rockets. In this rainy climate, conifers do indeed grow like weeds.

So how does all this forest disturbance affect bees? After listening to a number of presentations at the PNW Pollinator Summit last week, I learned that woodland bee populations generally behave exactly as I have observed, and the cycle is completely predictable.

No sun, no bees

Not many bees live in dense coniferous forest for two reasons. First, conifer trees do not produce flowers themselves and, second, the forest floor is too dark to support flowering plants. In my area, a thick canopy of trees passes enough light to grow of variety of ferns, mosses, lichens, and mushrooms on the forest floor, but not many bee-attractive plants.

However, as soon as a section is logged, the light comes flooding in. Seeds that have remained dormant for years suddenly have a reason to live, and the logged area bursts into flower with forbs, shrubs, and small flowering trees. Bees quickly arrive from neighboring areas, and you can find them the very first year after a cut.

Soon after logging operations end, I find aggregations of sweat bees in the ground, longhorn bees plying the thistles, and honey bees in the fireweed. I find bumble bees in the salal and Oregon grape, while leafcutters and tiny Ceratina work some of the smaller blooms. Butterflies arrive, too, as well as an assortment of moths, beetles, and pollinating hover flies.

Early seral communities

The first stage of forest regrowth is called the early seral stage. Early seral is simply the very first plant community that establishes itself after a disturbance. The disturbance could be caused by forest fire, volcano, flood, wind, ice, or—in this case—logging. The landscape of an early seral stage is characterized by herbaceous plants including weeds, broadleaf shrubs, and various grasses. And along with these plants comes a host of animal life, including bees, birds, butterflies, and plant-consuming animals.

Unfortunately, the widespread use of herbicides to kill these plants delays the sunshine feast. Forest managers are expected to grow trees—not wildlife—so they battle the competition with spray. But without forage, there can be no brood rearing. Basically, re-establishment of animal populations is restricted until the trees reach a certain maturity that the foresters call “free to grow.” Basically, a free-to-grow stand of trees is one that is large enough and healthy enough to grow on its own and outcompete other plants.

Once the replanted stand is mature enough to outcompete other woodland plants, the herbicide treatments stop, and the plants that characterize first seral growth are allowed to proliferate. Once this happens, the bees, birds and other animals return and populate the area.

Trees get a head start

As you can imagine, allowing the planted seedlings to have a head start shortens the length of time before a shaded canopy returns. As soon as a canopy begins to form, the shade-intolerant species die off. Then, in a few more years, you are back to dense shade, conifer trees, mosses, and ferns.

Early seral growth is extremely important to animal populations. Some biologists refer to these areas as animal reservoirs, a place where bees, birds, and other species can flourish. Even managed honey bees find them extremely attractive. With any luck, many of the species will move on to the next logged location as the shade sets in, and in this way, perpetuate their populations.

Time for change

Due to better understanding of the role of pollinators in a healthy planet, some forest managers are investigating ways to extend the early seral stage of regrowth to accommodate the insects while still turning a profit from trees. Others are trying to figure out how and why certain forestry laws interfere with pollinator recovery.

For example, is it best to pile the slash (twigs, branches, root balls, etc.) or leave it strewn across the landscape? Should native plants be seeded in the recovering areas, or should it be left alone? Should the soil be turned? Must herbicides be used on invasive plants?

What is best for forest bees?

At this point, the answers to many of these questions are not clear. We do know that ground-nesting native bees love bare soil. After logging operations, nests are found on skid roads and in places where slash has been removed. Equally attractive are places were the slash has been piled and then burned, leaving mineral-rich deposits.

On the other hand, cavity nesting bees often reside in the slash itself, especially in wood containing beetle holes. In addition, slash piles are famous for providing cover for all kinds of wildlife that is suddenly left without a protective forest. The piles become homes for mammals, reptiles, birds, and other invertebrates including beneficial insects.

And while invasive plants are generally considered bad, some need careful evaluation. Some bees, such as the tiny masked bees, Hylaeus, prefer invasive Himalayan blackberry vines for nest building, and dozens of other species use it as a bountiful source of pollen and nectar. Once the forest canopy closes, the blackberry will disappear, so how much management—and how much herbicide—does it really require?

New bee frontiers

For me, it is exciting to see so many different groups of people becoming interested in bee conservation. Until I attended the PNW Pollinator Summit, I never really thought about bees in the forest. Although I often hunted through newly logged areas looking for bees to photograph, I never really thought of those areas as a conservation resource. Now I’m thinking, dah! Of course it’s a resource—and one that deserves a closer look.

Rusty
Honey Bee Suite

Bees in the forest: Ground-nesting bees like this <em>Andrena</em> need bare soil for nest building.
Ground-nesting bees like this Andrena need bare soil for nest building. © Rusty Burlew.

Comments

Steve Bear
Reply

These are good thoughts you share.
I see it all here in Colorado.
Thank you Rusty!

Jennifer
Reply

Excellent post, thank you. It would be great if there could be a more integrated approach as usually these situations are due to a lack of knowledge and understanding, and some minor adjustments can make a big difference.

E.T. Ash
Reply

This is a perfect habitat for ‘the other pollinators’. Always good to recognize your place (in life and in a landscape) and also those places where you need not dwell long. Some years ago I kept honeybees in small numbers, basically to pollinate small truck crop operation in a predominately souther pine forest environment. I decided beyond the small plots for growing garden vegetable the landscape was about a like desert for a honeybee. You could maintain small number with a bit of feeding but not enough to really get to any kind of economical viable scale.

Gene in Central Texas…

Katy Pye
Reply

Thanks for another insightful article. Happy to hear the industry is looking at the bigger picture. I walk in our nearby CA coastal state forests almost daily, and some bees and butterflies are there in spring and summer. However, it seems remarkable how “quiet” these rich and diverse ecosystems remain. Someone recently explained why there are few birds and it’s the same reason there aren’t many pollinators – a lack of food. Bombus melanopygus (and another bumble I can’t identify) are often busy on the Labrador tea and manzanitas if they are in the sunshine or partial shade. I, too, get the circling bees around me in the beginning of the season. These are usually in more shaded forest areas, although not dark ones. Perhaps they are hornets that build the big tree nest colonies I’ve seen. None have slowed down long enough to let me figure out who they are. Obviously, they’re in territorial mode, although none have been aggressive. I’ll now focus on more species, since we share many of the same. When the sun returns and the weather warms.

Rusty
Reply

Katy,

This year I’m taking my butterfly net along with me. I just need to catch one long enough to get a good look. For some reason, I’ve always thought they’re bumbles, but now you’ve put doubt in my mind. We should compare notes.

Katy Pye
Reply

I’ll make it a point to see if I can figure out what’s buzzing early on in our usual forest walk. Would be great to compare notes.

Mike
Reply

New to you and bees. Thankful for info and hunger for more. On wild bees and their role as pollinators. Was under impression that Einstien said our civilization would starve if lost honey bee. Thank you for all your knowledge. Bet it didn’t come easy.

Rusty
Reply

Mike,

I’ve heard many times that Einstein didn’t say that, but in any case, it’s not true. Without honey bees, our modern form of agriculture would certainly need to be changed, but life would go on.

Bill Abell
Reply

Hi Rusty,

Interesting post. Neighboring landowners select cut about 50 acres of their 300-acre poplar/elm/oak forest over the last year. It will be interesting to watch the return of blackberry and other shrubs and plants over the next couple of years. I expect that the deer/bear and my honey bees will be overjoyed. I do mourn the loss of the Tulip Poplar which I consider to be one of the most handsome trees of the Middle Atlantic states, but we have plenty of our own.

Rusty
Reply

Bill,

I have mixed emotions about losing or cutting trees. I adore trees and cringe to see them come down. At the same time, the sun is a welcome sight and the small plants love it. I try to be philosophical about the process.

Michael Wilson
Reply

I have five colonies and 130 acres of thick forest. I have considered thinning the trees to improve the timber, but it did not occur to me that the loggers might actually help my honey bees. That’s the tie-breaker. Thank you for this post.

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