Category Archives: fall foliage
Snow on October 15! At first it was fun. Rolling balls for the snowman, I had to keep stopping to pull out black walnut leaf ribs — enough to make three dozen Eves, at least. Sure, give him a blaze-orange cap. Maybe he’ll come to life and wreak some minor havoc.
Snow fell throughout the afternoon and evening, fell faster than it could melt onto a ground that was still unfrozen. (Hell, we’d just gotten our first frost the day before!) By Friday morning, the power was out and the phone was dead. There were three to four inches of heavy, wet snow in the vicinity of the houses, and five inches at the top of the field. Sitting outside to drink my coffee around 8:00, it sounded as bad as any icestorm we’ve ever had, with loud cracks and crashes every few seconds. The trees seemed to be taking “fall” a bit too literally.
The bigger-leaved trees took it the worst: oaks, maples, tulip poplars, black locusts, and cucumber magnolias all suffered extensive pruning and occasional bole-snap. The damage was localized, presumably corresponding to wherever snow fell the hardest and stuck the longest. This was a very elevation-dependent snowfall throughout the region.
Numerous limbs and broken treetops, and around a dozen toppled mature trees, came down across the Plummer’s Hollow Boulevard. It took our new neighbors and caretakers, Troy and Paula Scott, two days to clear them all. Damage petered out along with the snow about a quarter mile from the bottom.
We’ve had October snows before, but none so heavy or so early. Of course it was beautiful — but some kinds of beauty we could definitely do without.
Plenty more damaging storms have hit Plummer’s Hollow, but it’s been a while since the oaks have taken this hard a beating. Icestorms rarely affect them. Although of course that’s in part because icestorms generally don’t occur until after the leaves are all down… knock on wood.
That was the view of Laurel Ridge on the day after Thanksgiving, showing that well over half the oaks not only retained their leaves, but retained their colors, as well. Most years, the trees would be bare by now.
Using freely rooted, field-grown Populus in two Free Air CO2 Enrichment Experiments (AspenFACE and PopFACE), we present evidence from two continents and over two years that increasing atmospheric CO2 acts directly to delay autumnal leaf coloration and leaf fall.
In an atmosphere enriched in CO2 (by ~ 45 % of the current atmospheric concentration to 550 ppm) the end of season decline in canopy Normalized Difference Vegetation Index (NDVI) – a commonly used global index for vegetation greenness – was significantly delayed, indicating a greener autumnal canopy, relative to that in ambient CO2. This was supported by a significant delay in the decline of autumnal canopy leaf area index (LAI) in elevated as compared to ambient CO2, and a significantly smaller decline in end of season leaf chlorophyll content. Leaf level photosynthetic activity and carbon uptake in elevated CO2 during the senescence period was also enhanced compared to ambient CO2. The findings reveal a direct effect of rising atmospheric CO2, independent of temperature in delaying autumnal senescence for Populus, an important deciduous forest tree with implications for forest productivity and adaptation to a future high CO2 world.
“Future atmospheric CO2 leads to delayed autumnal senescence,” by Gail Taylor, Matthew J. Tallis, Christian P. Giardina, Kevin E. Percy, Franco Miglietta, Pooja S. Gupta, Beniamino Gioli, Carlo Calfapietra, Birgit Gielen, Mark E. Kubiske, Giuseppe E. Scarascia-Mugnozza, Katre Kets, Stephen P. Long, and David F. Karnosky, Global Change Biology (OnlineAccepted Articles). See also Why Autumn Colors Are So Late, which summarizes the findings. (Hat tip: Meanwhile, back in the holler.)