32 Arnoldia 78/3 « February 2021 
been removed—either recently or long ago—is 
in a deep carbon debt because the land stores a 
fraction of the carbon it once stored as a forest. 
Energy Use 
Trees, of course, also have other climate-related 
implications for my property. Trees standing 
within sixty feet of my house reduce home 
energy expenditure and carbon emissions by 
cooling the house in summer and insulating 
it from cold winds in winter. Not surprisingly, 
large trees provide significantly greater energy 
reductions than do small trees. A thirty-inch- 
diameter red maple located on the west side of 
a house would reduce carbon dioxide emissions 
by almost seven-fold compared to a two-inch- 
diameter red maple that is similarly placed.!8 
One caveat is that trees, especially conifers, 
located on the south side of a house increase 
winter fuel use by blocking solar radiation; but 
the drawbacks are generally offset by the sub- 
stantial year-round benefits of trees located on 
the other three sides of a house. For example, 
if a thirty-inch white pine was growing on the 
south side of my house, it would increase win- 
ter fuel use slightly, while still providing some 
summer cooling, resulting in an estimated 
10 pounds of additional carbon dioxide emit- 
ted annually. But the same tree on the north 
side of the house would reduce winter fuel 
use—and provide greater summer cooling— 
resulting in the reduced emissions of an esti- 
mated 335 pounds of carbon dioxide annually.!” 
Trees, therefore, play an important role not only 
in sequestering and storing carbon but also in 
reducing household carbon emissions. 
Habitat and Biodiversity 
Natural climate solutions can also provide 
important forest habitat. Trees, as they age and 
grow larger, provide nesting and denning sites 
for a host of birds and mammals.”° They create 
deadwood that provides food for insects and 
develop large crowns that supply an abundant 
seed source. Even scattered trees with trunks 
at least sixteen-to-twenty inches in diameter 
in an urban setting can have outsized effects on 
bird diversity and abundance—a role that has 
caused researchers to describe large urban trees 
as “biodiversity hotspots.””! 
Reforestation of fields and lawns can provide 
additional young forest habitat (when the trees 
are fifteen years of age or younger), an ephem- 
eral and uncommon habitat in the northeast- 
ern United States. Several species of birds (like 
chestnut-sided warbler, prairie warbler, indigo 
bunting, and brown thrasher) and the rare New 
England cottontail prefer dense, low woody 
vegetation found in young forests, shrublands, 
and disturbed open woods and are generally not 
found in closed forests.” 
Depending on how many trees are retained or 
regrown on a property, and where the property 
is located, a small parcel may serve as a green 
oasis in an otherwise developed environment, 
or as an uncommon vegetation structure in a 
landscape of mostly mature forest or field, or 
as an extension of a larger forested patch. My 
property best exemplifies the last scenario, as 
it abuts one hundred acres of contiguous for- 
est. I frequently see and hear wood thrushes, 
veeries, barred owls, and pileated woodpeck- 
ers on my property. These species generally 
prefer mature forests or are associated with 
larger trees, and the wood thrush is listed as 
globally “near threatened” by the International 
Union of Conservation of Nature.?° Such spe- 
cies would almost certainly avoid my property 
if I converted my woods into lawn. Given that 
North America has lost almost 30 percent of 
its total bird population in the past fifty years, 
the natural climate solutions presented here 
applied across a multitude of small properties 
could make a real difference in stemming these 
population declines.”* 
Management for Natural 
Climate Solutions 
In general, the less I manage my property, the 
more climate benefits it will provide. Some 
tending, however, is important to allow trees to 
continue growing to their full potential. Lianas 
like the non-native oriental bittersweet (Celas- 
trus orbiculatus), which thrive in the edge habi- 
tats characteristic of residential properties, are 
best cut and removed when they are growing up 
trees and over shrubs. Bittersweet will reduce 
the growth rate (and carbon uptake) and even- 
tually kill trees by intercepting much of the 
sunlight in the canopy and by strangling the 
