I arrived at Blue Oak Ranch Reserve (BORR) today to a landscape completely different from when I last left it in mid-November. Brown hills are now verdant. Green leafed oak canopies are now lichen and mistletoe covered branches devoid of foliage. Dust and hard-packed earth are gone, replaced with puddles and mud. That this transformation happens every year doesn’t make it less remarkable.

I’ve now spent over a year of my life at this University of California property in the hills above San Jose. The fifty-day-long class I teach three times a year, California Ecology and Conservation, begins and ends each run here. Therefore, my six yearly visits are regularly spaced one-week stints. It feels as though I experience BORR as a series of vignettes, each visit a snapshot unique enough that I can name it based on which new flowers are in bloom or which new critters abound: late March (shooting star), mid May (mariposa lily), late June (dragonfly), mid August (tarweed), late September (tarantula), and mid November (tiger salamander). In most years, the most dramatic mid-year change is May to June, when the hills shift from green to golden.

I’ve been visiting BORR regularly since 2018. It’s amazing to think about how much change I’ve seen in even that narrow window. A fire burned half the reserve in 2020. A snow storm in early 2023 caused major damage to many tree limbs. Drought years and wet have shifted the timing of seasons and the levels of the ponds that dot the landscape. Feral pigs have uprooted large areas of meadows in their relentless search for roots and grubs. Invasive star thistle populations have been brought under control, but invasive mustard seems to be taking over the wetlands. The turning of seasons begins to feel like a background beat underpinning a larger song of change.

However large the transformations I’m witness to, they pale in comparison with those that happened 200 years ago. Spaniards first, and then Americans pushing west, hunted out the native elk and pronghorn, replacing them with cows. To feed their bovine investments, they seeded the land with annual Mediterranean grasses and introduced many additional non-native flowers in the process. That most noticeable of annual changes—hills vacillating from tan to green and back—didn’t occur before the 1800’s.

With the perspective of deeper time, the current landscape looks even stranger. When human populations began increasing in the state around 12,000 years ago, they hunted out megafauna and introducing much more frequent fire. Before then, BORR would have been a densely brushy place full of mastodons and ground sloths. Even the climate itself has been in its current form of cool wet winters and hot dry summers for less than 5 million years. Prior to that—a mere blink of the eye in geologic terms, BORR was a cool, wet temperate rainforest. But that long ago the hills themselves weren’t even there. BORR is part of the Diablo Range, which only formed 2 million years ago.

I’m planning on visiting BORR for many years still, and I’m excited and (and a little nervous) to see what changes the future holds. While prolonged droughts and the continuing onslaught of invasive species chip away at native biodiversity, the reserve staff and others are fighting back, planting oak trees and native grasses, and mowing and pulling invasives. All I know for sure is the next time I’m back, things will be different.