Bugs in the Woods

                                 

Guest post published here with permission from the author.

Bugs in the Woods

By Ethan Tapper 

Forests are complex, intricate, and nuanced, and also massive, expansive, and interconnected. To be responsible forest stewards we need to both zoom out to understand our role in a giant landscape and zoom in to recognize the tiny pieces and parts that make forests work. We must (somehow) hold both of these realities in focus as we take care of our forests. 

This month I want to zoom-in, to talk about invertebrates. Simply put, invertebrates are organisms without spines, an incredibly diverse group of critters that includes everything from insects to sea sponges, squids, slugs, and worms. What most people call “bugs,” are arthropods, a sub-group of invertebrates that includes insects, spiders, and even lobsters.

Invertebrates are an incredibly adaptive and resilient bunch, having been around since before the dinosaurs. In terms of sheer abundance and diversity, they stand alone: of the approximately 2 million known species on Earth, about 97% are invertebrates (900,000 species are just insects), with somewhere between 8 million and 30 million species still undiscovered. Besides accounting for a huge proportion of our biodiversity, the sheer amount of bugs on Earth is startling: there are around 200 million insects for every human on the planet, about 300 pounds of insects for every pound of human. To put us in perspective, the combined mass of all the humans on Earth is about equal to that of all the ants, or the mass that all the spiders on Earth eat in one year.  

In Vermont, there are more than 20,000 known species of invertebrates, compared to 58 species of mammals. These invertebrates support our ecosystems in countless ways, mostly unseen. They are what biologist E.O. Wilson calls “the little things that run the world,” subtly working behind the scenes to make our world work. 

                                 Giant Ichneumen. Photo by Gary Sturgis

                                         

Invertebrates are the base of the forest food web, directly and indirectly feeding larger wildlife. Moth and butterfly caterpillars, for example, are critical sources of protein that songbirds rely on to feed their young in the spring. Caterpillars and other bugs often have close, co-evolved relationships with one or a few different tree species, and so diverse forests are critical to providing habitat for them and the species that eat them. 

Invertebrates are also decomposers, turning organic material like wood into soil. Soils are largely biological in nature – their physical and chemical composition a result of being passed through the bodies of countless tiny organisms, transformed by mites, springtails, nematodes, and more. A handful of forest soil may contain thousands of invertebrates of hundreds of different species, not to mention millions or even billions of organisms if you include bacteria, protozoa, algae, and fungi. 

Invertebrates perform a huge number of other essential functions. Some, especially flying insects like flies, beetles, or Vermont’s more than 300 species of native bees, are pollinators, helping more than two-thirds of Vermont’s plant species reproduce. Others, like ants, disperse the seeds of some of our native spring wildflowers. The list goes on. 

Not all is good with bugs in the woods. Some invertebrates are non-native tree pests, like the Emerald Ash Borer (EAB) and Hemlock Wooly Adelgid (HWA). Some non-native bugs which are celebrated in agriculture – the Eurasian honeybee and earthworms – can be problematic in our ecosystems. Non-native invasive plants like honeysuckle, buckthorn, and barberry take over forests, providing habitat for only a tiny fraction of our invertebrates. For many reasons, invertebrates are going extinct at an incredibly fast rate, with as many 100,000 species lost since the 1600s and 40% of known invertebrate species thought to be under threat of extinction. 

Invertebrate habitat is as diverse as they are. They live in rotting wood, in soil, in the leaves and branches of young, healthy trees, and the complex bark of big, old trees. On a large scale, the most important thing we can do for invertebrates is to protect our forests from fragmentation and loss, managing for diverse, intact, connected landscapes. On a smaller scale, we can manage for complex forests, encouraging different sizes, ages, and species of trees while also leaving some big “legacy” trees, dead standing trees, and lots of deadwood on the forest floor, and dealing with biodiversity threats like non-native invasive plants.

Great things come in small packages. As strange as it seems, healthy populations of bugs are critical to the integrity and the resilience of our forests and the beauty and function of our world. 

Ethan Tapper is the Chittenden County Forester for the Vermont Dept. of Forests, Parks, and Recreation. See what he’s been up to at: https://linktr.ee/ChittendenCountyForester 

Note from Bernie, RELATED READING

Read about how leaf litter, and plant debris along with native plantings under trees provide critical shelter and habitat for one or more life cycles of moths, butterflies, and beneficial insects such as bumblebees, fireflies, lacewings, and beetles. Other benefits are improved soil, food for songbirds, and pollinators.

Read more in this illustrated article on Keystone plants and soft landings by Wild Ones Minnesota. ©2021 Heather Holm and Neighborhood Greening. Developed in consultation with Desiree Narango, Ph.D.; artwork by Elsa Cousins.

https://www.pollinatorsnativeplants.com/uploads/1/3/9/1/13913231/softlandingskeystonehandout.pdf