Iappreciate the sense of completion in the landscape at this time of year. The fallen leaves, the brown stalks of plants, the bare tree branches like sculptures against the sky are what remains of the wild rush of color and the lushness of summer, and I find it peaceful and settled.
With the drought this summer and fall, I watched changes in the landscape that I haven’t seen before, like double rounds of dormancy. When all the ferns turned brown and fell over from the heat and lack of rain, it looked like fall in August. Then after a few rainfalls in September, by early October there were new signs of fern growth poking through the brown layers. Still visible since we’ve had such an extended fall with temperatures that are more common in September than November, these fronds are bits of brightness.
It’s curious, these ways that plants know to go dormant and stop growing, a mix of hormones and chemicals that respond to climate signals like light, temperature, precipitation and shifts in available daylight. Phenological changes like germination, bud break, blooming, fruiting and dormancy are all triggered and impacted by climate. Dormancy is a plant’s response to conditions that no longer favor its survival. It knows that if it tried to keep growing, it would die. Instead, it hibernates. This is a measure of the cold-hardiness in plants, the way that they can go into dormancy and then begin growing again when conditions are right.
Hardiness zones, which define the average high temperatures for an area, help gardeners know the plants that will survive the winter outdoors. Rosemary, for example, a perennial herb, is not hardy. Its USDA zone is 8 to 10, where winter temperatures are between 10 and 40 degrees. That is not the Hudson Highlands, where winter temperatures can drop as low as minus 10 degrees.
I plant rosemary in a container and bring it in during the winter. It smells nice and works well with cold-weather cooking, like roasting. So my rosemary never enters dormancy because I provide it with the conditions to survive and keep growing. I artificially create an environment where its climate signals aren’t triggered.
Dormancy is different from death for a plant but sometimes it’s difficult to tell the difference when conditions like an extended drought occur. In the lawn, grass that comes up in your hand when you pull on it is dead. If it stays attached to roots, it is dormant.
Other plants, like native perennials, are pretty hardy and can survive periods of drought or other harsh conditions since they evolved in this environment and ecosystem. They know when to call it quits for a while and enter early dormancy. Although a dead plant and dormant plant look similar, if the roots are intact and stable, the plant should be expected to recover.
The impacts of climate change, like the unseasonal temperatures we’ve had recently — early season warming followed by snow or ice storms, heavier rainstorms and so on — are all impacting phenology in our area and sending confusing signals to plants and trees. Data shows that fruit trees are blooming earlier, for example, raising the risk of a killing frost that can wipe out a crop.
The drought this season impacted available food for wildlife. I can observe the impact by the feasting of hungry deer browsing on plants that were left alone over the past 10 years I’ve been paying attention. It’s unusual behavior for a deer to snack on goldenrod and asters, but necessary because the drought impacted fruiting and plant survival of their other food sources. That list of species that deer won’t eat in the landscape gets shorter every year, it seems.
To participate in tracking phenology, sign up for a citizen science project like Nature’s Notebook at the National Phenology Network (usanpn.org). Founded in 2007, it has an extensive data set provided by volunteers and partner agencies that notes where changes are taking place in the natural world in response to climate change that can be used to show vulnerabilities and risks.
Even if a citizen science project seems like too much of an undertaking, find a plant or tree in your landscape and check it frequently. Take notes. Keep it up for a couple of years and it could reveal interesting insights.
