Trees provide a multitude of benefits to cities, including cleaning the air, filtering water runoff, and improving quality of life. Urban areas, however, are losing these plants. According to a study conducted by the USDA Forest Service, these areas have lost around 36 million trees.

1. Pavements a Better
Predictor of Scale-Insect
Abundance in Dying Trees
Affordable Tree Care

2. Trees provide a multitude of benefits to cities, including cleaning the air, filtering water
runoff, and improving quality of life. Urban areas, however, are losing these plants.
According to a study conducted by the USDA Forest Service, these areas have lost around
36 million trees.
When it comes to tree death, harmful insects can cause plants to wither and die. Scale
insects, for instance, can attach themselves onto a plant and suck out its nutrients.
Individuals can check for the abundance of these parasites on trees by merely looking at
the ground, particularly on a hard surface. A study published in the journal Oikos found
that impervious surfaces, such as pavements, near trees were a better predictor of the
proliferation of scale insects. This means that these surfaces are a better predictor of poor
tree health.
Poorer Tree Health in Midrange Cities
Researchers from North Carolina State University investigated how the interaction of
scale-insect abundance, latitudinal warming, and urbanization affected urban tree health.
They predicted that trees in lower latitude and warmer cities at lower levels of
urbanization would have poorer health than those at higher and cooler latitudes due to
the interaction of herbivory, latitudinal temperature, and urbanization.

3. They evaluated their predictions by surveying the proliferation of scale insects on Acer
rubrum (red maple) in eight cities in the U.S. spanning 10 degrees of latitude.
Additionally, they estimated urbanization at two extents: a bigger one that recorded the
surrounding urban landscape, and a local one that represented the direct effects on a
single tree.
The results showed more scale insects on red maples in the midrange of the eight cities.
The places in that midrange had poorer tree health, mostly attributed to high volumes of
the said parasites.
Controlling Scale Insects
Scale insects, when left unchecked, could weaken (and eventually kill) the host. Managing
the infestation, therefore, is paramount. When it comes to parasite control, an article
from Iowa State University suggests introducing predators, such as lady beetles, and
parasitoids (small parasitic wasps) to attack and significantly decrease the populations of
scale insects. Another form of control would be to prune out and discard heavily infested
branches or stems.
Study author Michael Just and his colleagues learned that natural areas, such as forests,
did not translate in their research. He added that the team might need to look at other
natural-system theories they can use in urban areas. This is important, especially if the
group wants to have predictive and dependable ecological models.

4. Sources:
https://affordabletreecareslc.com/
https://news.ncsu.edu/2019/03/urban-effects-on-trees/
https://onlinelibrary.wiley.com/doi/10.1111/oik.05874
https://thecityfix.com/blog/urban-trees-boost-quality-life-city-dwellers-around-world-
livability-tree-canopy-ben-welle/
https://www.care2.com/causes/our-cities-are-rapidly-losing-trees-heres-why-that-
matters.html
https://hortnews.extension.iastate.edu/scale-insects
https://www.sciencedirect.com/science/article/pii/S1618866717307094?via%3Dihub#!