Big Leaf Maples - Acer macrophyllum
Local Color!
Up in the Lakes Basin there are still a few astounding groups of golden Cottonwood and Aspen trees, but the majority of of the trees, bushes, and ground cover have lost their leaves and color. However, at lower elevations the trees and shrubs are still in vibrant warm hues! In my neighborhood the Black Oaks, Big Leaf Maples, Creek Dogwoods and Indian Rhubarbs are glowing with oranges, golden-yellows, and even some pinks! It's a photographers paradise!
Black Oaks - Quercus kelloggii
The best fall colors happen after a spring and summer that are somewhat wet, followed by a sunny autumn with warm days and cool, but frostless, nights.
As the nights get longer in the fall, the transportation of chlorophyll from the leaf to the branch, and from the roots to the leaves becomes blocked. As the chlorophyll is blocked from the leaves, it disappears completely.
This lack of green chlorophyll allows the yellow (xanthophylls) and orange (carotenoids) pigments to be visible. The red and purple pigments (anthocyanins) are manufactured from the sugars that are trapped in the leaf. These pigments are what cause the vivid color changes in leaves!
So far we've had the perfect weather for vivid fall colors! Rain is in the forecast for this week, so hopefully the fall colors will last a while longer!
Black Oaks on Highway 49 - Quercus kelloggii
The beautifully colored Fall leaves don't last forever. As the days shorten and temperatures drop, not only do the leaves change color, but a process called "abscission" begins. The leaves don't just fall off the tree, they are actually being pushed off the tree by the tree itself! Keeping lots of dead leaves on a tree could cause breakages from the weight of snow accumulating on them. As Fall progresses a layer of cells, known as the abscission layer, starts to grow between the end of the leaf stalk and the twig supporting it. These cells slowly grow and cut the leaf off from the tree without leaving an open wound.
I was wondering why oak trees retain their leaves longer than other local deciduous trees, and this is what I found out. Oak leaves last longer because oaks form an abscission layer much later than other species of deciduous trees. Oak leaves often remain attached to the tree throughout the winter. This retaining of dead leaves is called "marcescence." Trees that exhibit marcescence are called "everciduous."
Indian Rhubarb & Willow - Darmera peltata & Salix sp.
Indian Rhubarb grows along rocky streams and river beds throughout the Sierra, up to 6,600' in elevation. The leaves are huge, up to 2' wide, and the leaf stalks can be 1-3' tall! They grow from rhizomes that hug the underwater rocks. In fall, the leaves turn yellow-orange and sometimes a lovely salmon pink in color! They are one of my absolute favorite river plants!
Indian Rhubarbs - Darmera peltata
During the growing season, chlorophyll is continually being produced and broken down and leaves appear green. In early autumn, in response to the shortening days and declining intensity of sunlight, chlorophyll production slows down, stops, and eventually all chlorophyll is destroyed. The colorful yellow (xanthophylls) and orange (carotenoids) pigments that are present in the leaf, are then unmasked and show their colors. The red and purple pigments (anthocyanins) are manufactured from the sugars that are trapped in the leaf. These pigments are what cause the vivid color changes in leaves!
If you see some brilliant pinkish-red in the forest, chances are it's Mountain Dogwood, one of my favorites!
Golden Pholiota - Pholiota aurivella
Fungi!!!
Due to the recent rain and cooler temperatures, Fungi have started popping up in our neighborhood as well as in the Lakes Basin! Golden Pholiota are found on logs, stumps, or wounds of living trees, and occasionally on woodchips! They are gilled fungi. The following information about fungi is from the website at:
" Fungi are heterotrophs, because they are not able to ingest their food like animals do, nor can they manufacture their own food the way plants do. Instead, fungi feed by absorption of nutrients from the environment around them. They accomplish this by growing through and within the substrate on which they are feeding. Numerous hyphae network through the material in which they are growing. The hyphae secrete digestive enzymes which break down the substrate, making it easier for the fungus to absorb the nutrients which the substrate contains.
This filamentous growth means that the fungus is in intimate contact with its surroundings; it has a very large surface area compared to its volume. While this makes diffusion of nutrients into the hyphae easier, it also makes the fungus susceptible to desiccation and ion imbalance. But usually this is not a problem, since the fungus is growing within a moist substrate.
Western Varnished Conk - Ganoderma oregonense
The Western Varnished Conk is aptly named with its glossy surface. To me, its surface feels like polished leather, and isn't slimy or wet like it looks! It is a pore fungi, with millions of tiny pores on its under-surface, and is usually found on dead or dying conifers.
"Most fungi are saprophytes, feeding on dead or decaying material. This helps to remove leaf litter and other debris that would otherwise accumulate on the ground. Nutrients absorbed by the fungus then become available for other organisms which may eat fungi. A very few fungi actively capture prey, such as Arthrobotrys which snares nematodes on which it feeds. Many fungi are parasitic, feeding on living organisms without killing them. Ergot, corn smut, Dutch elm disease, and ringworm are all diseases caused by parasitic fungi.
Mycorrhizae are a symbiotic relationship between fungi and plants.
Most plants rely on a symbiotic fungus to aid them in acquiring water and nutrients from the soil. The specialized roots which the plants grow and the fungus which inhabits them are together known as mycorrhizae, or "fungal roots". The fungus, with its large surface area, is able to soak up water and nutrients over a large area and provide them to the plant. In return, the plant provides energy-rich sugars manufactured through photosynthesis.
Because mycorrhizal associations are found in so many plants, it is thought that they may have been an essential element in the transition of plants onto the land."
To reproduce, mushrooms produce spores. Basidia are the microscopic, club-shaped, spore-bearing structures in mushrooms. There are four main structures in mushrooms that contain the basidia; gills, pores, teeth, and clubs or branches! Most people are familiar with the gill structure pictured above left. Pores are found on Bolete fungi and others, and are the small holes (actually tubes) on the smooth underside of the mushroom cap. Teeth are found on Lion's Mane fungi as well as others, and look like tiny hanging icicles. Clubs and branches are found on Coral Fungi. Thousands and thousands of basidia are arranged along the outside edges of the gills, the insides of the tubes that end in pores, and on the outside of the teeth, clubs, and branches!
Yellow Coral Mushroom - Ramaria rasilispora
Coral fungi have upright branches which are covered in microscopic spores!
Club/Thumb Fungi - Spathularia neesii
These odd shaped fungi are only about half an inch tall. I've only seen them growing in wet mossy areas. They do kind of look like naked thumbs! Spores are born on the outside of these club-like fungi!
Webs of the Bowl & Doily Spider - Frontinella pyramitela
Spiders and their Webs!
After we got 1.5" of rain in two days, we decided to go down to the Canyon Creek Trail for a short hike. As soon as we started our hike, spider webs caught our eye! They were beautifully backlit by the morning sun! Just gorgeous!!!
Bowl & Doily Spiders (pictured above and below) are sheet web weavers. Sheet webs are horizontally spun, flat sheets of silk between tufts of grass or tree branches. These webs are made with individual strands or are woven as a thick sheet of silk, and the spider will also spin separate criss-crossed threads about the sheet. There are over 4, 600 species of sheet web weavers in the world! They are very tiny and don't use sticky thread, but rather entangle and snare prey in their dense webs.
Webs of the Bowl & Doily Spider - Frontinella pyramitela
Spider webs are pretty incredible structures. Spider silk is a protein fiber that varies in structure (up to 7 different kinds) depending on its use! Most silks have exceptional mechanical properties, including high tensile strength and extensibility. A given weight of silk is five times stronger than the same weight of steel! Some spiders repair their webs at night. Others eat their web and rebuild it daily! Some spiders, such as the Crab Spider, don't build webs at all and rely on camouflage and ambush to catch their prey!
Female Orb Weaver on her Web
The Orb Weaver web above was made by a female spider. The female spider doesn't get stuck in her own web because she mainly travels on the non-sticky structural lines. Sometimes she has to walk on the sticky spiral lines, but her hairy legs have an oil that keeps them from sticking! Male Orb Weavers don't make webs. They spend their time cruising for females to mate. At this time of year, the females are laying their last clutch of eggs, and will die at the first frost. The eggs will overwinter, up to several hundred eggs in one egg sac, and hatch in the spring.
A perfect Orb Weaver Web!
Male Orb Weavers don't make webs. They spend their time cruising for females to mate. At this time of year, the females are laying their last clutch of eggs, and will die at the first frost. The eggs will overwinter, up to several hundred eggs in one egg sac, and hatch in the spring, The eggs will overwinter, but the female and male spiders will die at the first frost. We haven't had a frost yet, so hopefully we'll see more spider webs tomorrow!!
What's happening in the Lakes Basin?
After 8 years of posting my blog, I've decided that I'm only going to post my blog every TWO weeks. Check back on November 15th for my next natural history blog.
Your questions and comments are always appreciated! Please email me at northyubanaturalist@gmail.com. Thanks!
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