This story was originally published byGrist.
Last fall, I invited a stranger into my yard.
Its not that Im a thoughtless gardener.
Photo: Leon Neal (Getty Images)
Climate change isscrambling the seasons,wreaking havoc on trees.
Some temperate andhigh-altitude regionswill grow more humid, which can lead to lethal rot.
Thats especially true of native trees.
They are the first ones to suffer, he said.
Trees play a crucial role in keeping cities cool.
He went on to say that one kind of tree isnt enough.
We need a high number of diverse trees that can survive.
In other words, a whole new urban forest.
Now, he waits.
Were flipping that on its head and looking at what we want to grow, he said.
We want a good outcome for humanity.
But increasingly hot temperatures can shut down this process.
In extreme dry heat, the cells slacken and the stomata close, stopping water from escaping.
Making matters worse, distressed plants are more vulnerable to pests like theborer beetle.
Eighty-seven percent of the trees in Plano, Texas, are native species, for example.
That number is 66 percent in Santa Rosa, California, and 30 percent in Providence, Rhode Island.
To be sure, non-native trees have been a part of human settlements for a long time.
Plants oftenspread with human migration, and European colonists brought many species to other continents.
However, flora introduced from far away can also experience climate shock.
Currently, non-native trees typically come from climates similar to those trees they now stand alongside.
Until the seasons started going haywire, this made them well-suited to their adopted homes.
He will have to wait two years for the acorns to sprout and grow into saplings.
Martin plans to study at what point the trees leaves hit turgor loss in dry, hot conditions.
Examining leaf turgor loss cant be used to assess trees for every neighborhood in a city.
Parts of Sydney are facing increasingly humid summers in an otherwise temperate climate.
They are also mindful that the climate will change gradually and have laid out a phased planting plan.
Trees that thrive in the Sydney of 2060 may struggle in 2100.
Canada, for example, hasfunded the plantingofthousands of native treesin urban areas through its2 Billion Treesproject.
But he doesnt believe cities must completely abandon native species.
He hopes that some species can be saved with a process he calls upgrading.
Additionally, locale-adapted native species might continue thriving in woodlands like large city parks or green spaces.
Thats not the case in highly paved and built-up neighborhoods, where decreasing rainfall hurts trees more.
Everythings pushed to its limit in urban environments, Sjoman said.
That reality has many locales taking a block-by-block approach to planting guidelines.
But the city is also open to non-native species where plants face harsh conditions along streets.
Foresters say theres another valid argument for trying to keep as many native trees as possible.
The city has faced deadly heat domes and drier conditions in recent years.
Were not eliminating them, she said, but were being careful about where were planting them.
We often say were happy to do it where we can find a location, she said.
Urban tree experts dont expect introduced species to cause major disruptions to native wildlife.
A patchwork of species could create a buffer against tree-to-tree infection among the same species.
Some native animalsdo surprisingly wellalongside their new plant neighbors.
Animals might already be eating fruit from a new tree that grows somewhere else in their range.
For now, my manzanita is a small bush.
(Manzanita straddles the line between shrub and tree,which is not clear-cut distinction.
The definition of a tree is something that ornithologist David Allen Sibley said one could quibble endlessly over.)
This article originally appeared inGristathttps://grist.org/agriculture/climate-change-tree-urban-city-arborists-heat-drought-native-species/.
Grist is a nonprofit, independent media organization dedicated to telling stories of climate solutions and a just future.
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