Phenology report from Kaweah Oaks Preserve

The seasons of the Mediterranean climate are dramatic, changing swiftly from new green growth to brown withering leaves in a relatively short time. Given the drought conditions, the growth season can be even shorter leaving months of barren branches passing time waiting for the rains of fall to finally quench their thirst.

The heat of summer has fully arrived with relentless intensity. At Dry Creek Preserve the stamina of the Valley Oak trees is impressive. Their full lush green canopies contrast against the fields of crisp, dry grasses. The acorns are developing and what began as the bumpy cap is now filling out with the light green nut. These great trees stand tall and strong amidst sun, heat and low water reserves, the result of a four-year-long drought.

The leaves of the Sycamore trees are beginning to wither in these hot conditions. Their fruit production is low as they conserve resources in order to stay healthy and strong enough to withstand the duration of summer. In the foothills of Sequoia National Park the Blue Oaks are losing leaves rapidly. Most of the acorns that began to develop are dry and falling off of the trees prematurely.

The leaves on the Buckeye trees are drying up and falling off. Few leaves still cling to the branches leaving the light-colored bark visible through the sparse canopy. The Buckeye trees are conserving energy to grow the few nuts that cling to the branches.

At the Kaweah Oaks Preserve the Valley Oaks are showing signs of stress in these hot summer months. Their canopies are sparse with small leaves that are thin and light green in color. Very few acorns developed larger than a few millimeters in diameter.

The leaves on the Sycamore trees are losing their shiny green luster and turning yellow and brown. More than half of the leaves have fallen off the trees. Three months ago the thick green canopies adorned the top of these tall trees, which now show mostly bare branches and withering leaves.

The Elderberries have dropped most of their leaves and all their fruit. To see the barren Elderberries in this state in midsummer and to imagine next spring’s growth of a full leafy canopy is a testimony to the strength and tolerance that nature has to survive.

The month of June brought opportunities to speak to 75 people about the beauty and wonders of phenology, including 24 people at the California Garden Club Regional Meeting where I was the keynote speaker. The members were very engaged and interested in learning about phenology and how they can begin to monitor their own selection of trees. As a result of my presentation I was invited to speak at two local meetings of the California Garden Club in the fall.

Lynne Firpo is an interpretive ranger for Sequoia National Park, who has been doing a phenology internship with SRT at our preserves this year.