It's hard to be a street tree

Recently, you may have heard about the piles of snow dumped on Western New York courtesy of Lake Erie. This fall was not the first time the lake effect phenomenon has caused devastation in the region. In October of 2006 a lake effect storm, called 'Aphid' raged through the actual city of Buffalo (whereas, this years storm was actually south of the city). 

The aftermath of 'Aphid.' Image source: wikipedia commons

The aftermath of 'Aphid.' Image source: wikipedia commons

As part of the plant community, I know a narrow selection of Buffalonians, but those I know are quite passionate. They still talk of the devastation to the trees that this storm caused. According to NOAA:

Words cannot do justice to the astounding event, […]. It was the most unique in regards to destruction of trees and power outages, directly because of it’s out of season factor. Almost a million residents of the Niagara Frontier lost power, some for as long as a week, and tree damage was the worst in memory, especially to the lush vegetation in the many historic parkways and parks in the Buffalo area.
Tilia cordata, the little leaf linden is a common street tree in Buffalo (and many other places).

Tilia cordata, the little leaf linden is a common street tree in Buffalo (and many other places).

When walking through the city discerning eyes will spot trees of a certain age – those that are 12 or so years old now – that were planted to replace those lost during the storm. There are quite a few. (There are plenty of older trees too, so not all was lost.) 

Catastrophic events often lead to improvement on management. After the storm of 2006 all 16,800 trees that are part of Buffalos urban forest were re-mapped and are managed by the city using ARCGIS software.  

An urban forest is the collection of trees that grow in a city. This forest has important biological, social and economic benefits for those that live nearby. These trees filter the air, provide habitat for wildlife, decrease storm flooding, increase property values, and help instill a sense of community.

Street trees don't have much space to grow. If given plenty of space most tree roots grow out along the soil surface, not down into the ground. If street trees don't have much space for roots to grow they may easily be knocked over by wind, snow or flooding.

Street trees don't have much space to grow. If given plenty of space most tree roots grow out along the soil surface, not down into the ground. If street trees don't have much space for roots to grow they may easily be knocked over by wind, snow or flooding.

The life of a street tree is hard 

Thinking about all the trees in an urban forest is overwhelming. So lets focus on the trees right outside my window, Tilia cordata the little leaf linden. Although, it is native to Europe, this is a common street tree in Buffalo. It has a symmetric pyramidal shape, grows to about 50 feet tall in the city and has few pest problems. 

The two rows of trees that stretch from one end of the street to the other don’t quite meet in the middle, but still give the effect of somewhere that isn’t really in the middle of a city. In summer the lindens are swarmed with bees and wasps that first visit the heavy scented flowers, and later feast on honeydew secreted by aphid infestations. Squirrels and birds make their homes in the branches that are covered with shade giving leaves on warm days. 

During winter tree trunks often have snow banked around them. If drivers aren't careful pushing too much snow on a tree can knock it over. Trees also suffer physical damage from being hit by automobiles. 

During winter tree trunks often have snow banked around them. If drivers aren't careful pushing too much snow on a tree can knock it over. Trees also suffer physical damage from being hit by automobiles. 

There are lots of factors that make survival of a tree planted on a city street difficult. Space is limited by curbs, sidewalks, sewers and subways. Soil quality is often poor with few sources of nutrients for growing trees. Soils are also compacted from decades of rolling automobiles, which makes it hard for growing roots to expand. This leads to poor drainage, so tree roots might be marinating in excess water during storms. And we know what too much water can do to plant roots

Above ground life can be tough too. Tall buildings create lengthy shadows, and often act as wind tunnels. Automotive exhaust swirls around, and rain carrying chemicals falls from the sky. In the winter, tree trunks are the perfect place to bank piles of plowed snow. Errant plowmen, or spinning car drivers may nudge trees damaging bark and ripping leaves. 

If a growing tree gets in the way of power lines the middle section is often cut out. 

If a growing tree gets in the way of power lines the middle section is often cut out. 

I've mainly discussed the physical and environmental challenges that street trees face. Pests and diseases are also major threats to urban forests. A few months ago Alena wrote about one - Dutch elm disease, which wiped out most of the American elms. Once, there were lots of elm trees in Buffalo, judging by street and neighborhood names. 

Yet, despite winter storms, pests, diseases and some general negligence, city street trees persist - some even thrive. Hopefully, this past storm will be the hardest on the cities trees (and buildings) this year, and we just have regular winter storms to look forward to.

 

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