Eclipse through an Oak-Tree Camera

In northern California, where the August 2017 solar eclipse covered up to 75% of the sun, an oak tree served as a pinhole camera, a “natural optical phenomenon that occurs when an image of a scene at the other side of a screen (or for instance a wall) is projected through a small hole in that screen as a reversed and inverted image (left to right and upside down) on a surface opposite to the opening”.

Above, in the shadow of branches, the many crescents show the sun in eclipse. Tiny gaps between the oak leaves form pinhole cameras that project the sun’s image onto pavers.

Continue reading Eclipse through an Oak-Tree Camera

Advertisements

A Pair of ‘Peckers

One day last week we saw two species of woodpeckers in our oak tree, a coast live oak (quercus agrifolia). We seldom see woodpeckers, much less two different kinds on the same day.

My wife spotted a bird flitting through the oak tree. After consulting The Sibley Guide to Birds, we think it’s a female Nuttal’s woodpecker. We watched the woodpecker for a while, trying to get a good photo as it moved frequently from branch to branch, usually obscured by leaves. This woodpecker looks smaller than others we’ve seen.

Continue reading A Pair of ‘Peckers

The Native Garden

I enjoyed this piece from a new book by Art Wolfe, a nature photographer I admire. From The Art of the Photograph by Art Wolfe and Rob Sheppard,

The Native Garden
Not all nature photographers live in the wilds. In fact, both of us live in urban areas but enjoy creating inspiring gardens. Our yards provide us with connections to the natural world as well as places to play and experiment with photography close to home.
Much of both of our gardens is based on native plants. Native plants connect you with the wild of the area you live in and have a lot to offer, including beautiful flowers thoughout the growing season. Natives also attract a variety of birds and insects, even mammals. Exotic plants can create sterile environments for interesting bugs, or be too attractive to insects and demand toxic sprays. Natives attract a balanced variety of insects, from pollinators to predators, bees to butterflies, so are less likely to attract problem insects that can take over your garden.
Once you have a garden of natural outdoor space at your home, it’s easy to set up a camera and go outside! Gardens can also be useful stress-relievers. Going out and concentrating on the amazing insects that visit the flowers in the garden can put you in a better mood, lifting your outlook on life and nature. Focusing through the camera on a composition of native flowers, or trying to follow a native bee, might just keep you grounded and thankful for the beauty of life all around us.

———

Here’s a photo of a woodpecker on a quercus agrilofia, coast live oak, in our backyard.

Nuttal's woodpecker
Nuttall’s woodpecker

Mulching Coast Live Oak Leaves

As much as we like using arborist wood chips for mulch, we have concerns because the wood chips could spread Sudden Oak Death (SOD) to our coast live oak trees if infected plants are included in the load of wood chips.

Rather than bringing in mulch, we are using our oak leaves as mulch. The leaves of the coast live oak (quercus agrifolia, a California native plant) are thick and hard, so they don’t break down easily. We’re running the leaves through a leaf mulcher to break down the leaves. In the photo below, the mulched oak leaves are beige. This part of our yard has no oak trees and is sunny, so we brought in mulched oak leaves to help retain moisture and moderate the heat.

oak leaf mulch
oak leaf mulch

In this crop from the previous photo, you can see the gray wood chips and the beige oak leaves. We expect that the broken oak leaves will decay quicker than if they remained whole, once it starts raining again.

closeup of oak leaf mulch

The shrub on the left is an Arctostaphylos Sunset, a manzanita named after the Sunset magazine. A California native plant, the Sunset manzanita has glossy green leaves and small pink flowers. After seven years, it’s 3′ high and 5′ across. We use the Sunset manzanita to cap some large mounds. It’s easy to grow. We like it and have planted more.

After the Wildfire, +4 months

In California, where we get little rain between April and October, wildfire is all too common. On Saturday a California Native Plant Society (CNPS) group hiked in the hills south of San Jose, California, to look at a 40-acre area that burned in July 2013. To document nature’s renewal after the fire, we photographed the burn area before the rains, and we’ll return in the winter and spring to see the changes after the rain, to see how well the plants recover.

This relief map, a screenshot from Lightroom 5, shows the area where we hiked. My camera has a built-in GPS. The numbers indicate how many photos I took in that spot, but I’ll use the numbers to show where the photos were taken. The burn area started at the yellow marker, number 18. The brown lines on the relief map indicate equal elevation, so we can see that the hike started at the bottom of the hill.

Rancho Canada del Oro map
Rancho Canada del Oro map

The fire was within the Rancho Cañada del Oro Open Space Preserve. 2013 has been very dry — it’s rained only 2″ in 2013 and 3/4″ of rain since the July fire.

Marker 18 shows the bottom corner of the burn. The fire burned the grassland up the hill to the oak trees at the top.

Rancho Canada del Oro burn area
Rancho Canada del Oro burn area

This charred clump of fescue, a cool-season grass, is sprouting new shoots in the fall.

fescue shoots after the burn
fescue shoots after the burn

We hiked west to marker 15 and then hiked north up the hill to the trees.

up the draw to half-burnt oak
up the draw to half-burnt oak

The white flowers in the foreground are hemizonia congesta, hayfield tarweed, a California native plant. The tarweed in the photo below was just outside the burn area.

hemizonia congesta
hemizonia congesta

Here’s a closer view of the half-burnt oak, marker 12. Note that the leaves facing the hillside are brown while the leaves facing away form the hillside are still green.

half-burnt oak
half-burnt oak

This epilobium canum (California fuschia) is growing in the ravine just below the oak tree. A California native plant, it blooms in the summer. These fuschias are more healthy than the ones at home that we water every two weeks! Perhaps there was considerable water runoff into the ravine from fire fighting.

epilobium canum
epilobium canum

A patch of asclepias fascicularis, narrowleaf milkweed, is growing on the other side of the ravine from the oak tree. The narrowleaf milkweed is the sole food source of the monarch butterfly.

asclepias fascicularis
asclepias fascicularis

We hiked back down the hill and then around the hill to a gate on the ridgeline at the top of the burn, marker 11. The hillside was too steep for the group to hike directly up the hill.

This quercus agrifolia, coast live oak, located at the gate, lost its leaves in the fire, but a small green shoot has emerged just below the cut. Also a California native plant, the coast live oak is evergreen. It’s dormant in the summer, which helps it survive the dry California summer.

burnt coast live oak with shoot
burnt coast live oak with shoot

From this oak, the half-burnt oak is down the bare hillside in the bottom left.

half-burnt oak from ridgetop
half-burnt oak from ridgetop

We hiked out to marker 10 to see the burn area from the top of the ridge. Look at the yellow grassland and the green oak woodland to imagine how the burn area looked before the fire.

looking at the burn area
looking at the burn area

We’ll return in January after the plants get some rain.

Coast Live Oaks and Mulch

The coast live oak is a beautiful tree native to California.  To help our oak trees, we landscaped with California native plants and spread wood chips as mulch.  A disease called Sudden Oak Death (SOD) has spread through the San Francisco Bay Area, and it kills coast live oaks.  There’s a risk that SOD can be spread by bringing in wood chips, so we are exploring other mulch options.

Coast Live Oak

The coast live oak, quercus agrifolia, is an evergreen tree growing to 10 to 25 meters tall.  A native plant, the coast live oak has adapted to the long, dry summers of our Mediterranean climate.  However, if oaks are watered throughout the summer, they can get crown and root rot, which can shorten their life, so we landscape with native plants that require only occasional summer water.

When we landscaped the yard five years ago, we spread wood chips as a mulch to suppress weeds, add nutrients, and reduce evaporation. The original wood chips have gotten much thinner and need renewal.

We attended a SOD talk and a treatment class by researchers at the University of California at Berkeley.  We learned that the SOD pathogen, phytophthora ramorum, can be spread by wood chips and sawdust.  The pathogen needs warmth and moisture to become active, but the pathogen can live in dry wood until favorable conditions arise.  Generally, when a coast live oak is infected, it dies, so the consequence of an oak being infected by SOD is severe.

We get wood chips from arborists who prune and chip trees.  Unless the arborist is pruning and chipping our trees, we don’t know the identify of the trees being chipped, or whether the trees are infected.  In the Spring of 2011, volunteers sent in samples that were tested for the SOD pathogen, and the results were published.  SOD is widespread in the mountains near us, but trees in the valley floor are generally not infected.  In 2011 SOD spread rapidly due to a wet spring, and 97% of the trees tested in the mountains near us were infected.

“Experts predict as many as 90 percent of California’s live oaks and black oaks could die from the disease within 25 years.”  With the severe consequence (death) if an oak is infected, we don’t want to risk infection by importing wood chips or host plants that might carry the SOD pathogen.

We are trying approaches to mulch the oak leaves.  Coast live oaks are large and drop a lot of leaves each year.  The leaves are thick and stiff, so they don’t not decompose easily.  Dry leaves are brittle and will break when stepped on.  We’ve tried stepping on leaves or crushing them with gloved hands.  Oak leaves have sharp thorns on leaf edges.  This manual approach is very slow.  We’re considering purchasing an electric leaf mulcher to speed the process.

In summary, people with coast live oaks should consider risks of SOD when bringing in wood chips for mulch.  Mulch is valuable, so we’re exploring approaches to mulch our oak leaves as an alternative to wood chips.