Sunday, July 17, 2022

Live oak – a keystone species (and friend)

 Live oak is one of my favorite trees -- one of the many types of oaks in the world, but only growing in the US within a limited southern range. My nature journal entry is of a tree that’s about 20 years old, an acorn volunteer from a larger and much older live oak nearby. 

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I love discovering the many things that live oaks support. The bark on the trunks of older oaks is furrowed deep, often dressed with an embroidery of lichens, fungi, and mosses -- sometimes ferns. Look up into the branches and you will probably see several types of epiphytes, those plants that grow on others (not to be confused with parasites), and get sustenance from rain and air as well as sunlight. Sometimes called air plants, many epiphytes are from the bromeliad family – in Florida we have a variety of tillandsias and Spanish moss as the usual suspects. 

Some of these air plants collect water in bowl-like centers, created by the broad bases of their overlapping leaves. It becomes a good water source as well as a habitat for insect larvae that start their life underwater. Small insects attract the things that eat them – larger insects, spiders, anoles, and birds. The thick foliage and sturdy branches of live oak provide shade, cover and a retreat for bird and squirrel nests. About 5 years ago, I enjoyed watching a trio of raccoon kits scamper up and down the trunk of a mature live oak outside my office window as they grew to maturity. When the storms came, they high-tailed it to the 10-foot-high nest tucked under a large staghorn fern in the first fork. 

The leaves are larval food for several species of moths, plus a couple of butterflies. You might notice the tracks of leaf miners or the swellings from gall-forming insects. Live oaks are called “live” because they appear to be evergreen to many people, but they do drop their old leaves, waiting until spring when the new leaves emerge. Live oaks bloom in the spring, and although the catkins rely on wind pollination, they also offer pollen to bees and other insects. 

Oaks are well-known for acorns, not just as food for squirrels, but also for grubs, birds, and small and large mammals (even people). The nuts were processed to remove the tannins and eaten by humans all over the world. Acorn culinary history spans thousands of years, as a regular food source and later as a sustenance and survival food. Contemporary interest in acorn flour and nuts comes from the curious, the epicures, and the food and agriculture specialists working on food security for our future. 

Some of the species noticed over time!

Acorns start dropping to the ground in the fall, with some years (called mast years) welcoming an overabundance. Last year (2021) was a mast year, and we had acorns everywhere! Blue jays and squirrels left pock marks in the dirt and sand as they busily buried as many acorns as they could. Between the nuts on top and the divots below, it was dangerous walking ground.

Oaks are considered a keystone species, which means that they support a large community of living things. They support, shelter, and feed all sorts of life – from the smallest insects to deer and even bears. Live oaks have personal connections for me as well, besides the trio of raccoon kits. The first pair of pileated woodpeckers I spotted in Florida were on a live oak tree. The plonk-plonk of falling acorns has put me to sleep at night; the battles of jays and squirrels over a nut have amused me in the daytime. I enjoy trying to capture the textures and colors of the bark and leaves in my nature journal. There’s not much time to observe our two urban oaks, but I still notice an abundance of life just in passing. I’ve sketched live oaks often enough that I consider them old and beloved friends. 

I hope my words and nature journal entries help you see oaks in a new light. We appreciate the beauty and shade they bring, but they offer so much more. Planting or preserving one oak makes a difference: a cascade of life follows, and this is a wonderful thing! 

More on oaks: There is much more to learn about oaks. For an overview on the many values of oaks (for nature and ourselves), I suggest you start by watching a presentation by Dr. Doug Tallamy on his book “The Nature of Oaks” on YouTube: 

Mechanical pencil .7mm 
Micron Pigma 01, black 
Aquabee Super Deluxe Mixed Media sketchbook 6x9 in. 
Daniel Smith watercolors 
Niji waterbush, round M

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