Hexbyte Glen Cove Forest survival strategies for extreme cyclones

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How trees reacted to wind during a category-5 tropical cyclone (super typhoon Trami) in 2018. The wind and tree stem angle data describe that tree damage occurred from 1:10 to 1:20 on 1 October 2018 (rapidly changing wind speeds with strong sweep shown as the negative momentum flux u’w’). Before 1:10, all trees were swaying in the similar manner; just after 1:10, the trees in the control plot helped each other by frequently crushing their crowns, whereas the trees in the thinned plot confronted strong wind turbulent individually; when the winds became less strong, the trees in the control plot returned to the rest (original) positions, whereas the undamaged trees without any supports (in the thinned plot) remained at the leaned positions (never back to the rest positions). Credit: Kana Kamimura, Shinshu University

Trees in forests are prone to damage from strong winds. Despite extreme weather events becoming more prevalent, scientists have not yet fully understood why some trees are damaged and other trees survive. A team of researchers led by Dr. Kana Kamimura of Shinshu University succeeded in obtaining unique data when a forest under an ongoing study got hit by the category-5 tropical cyclone Trami in 2018, giving them previously undocumented information about the dynamic responses of trees damaged by wind.

As the climate changes, wind damage is expected not only in the current tropical cyclone-affected regions but in much larger regions consisting of trees that have never encountered such extreme conditions. Tropical cyclones are expected to migrate north (in the northern hemisphere) while also increasing in magnitude. To better protect forests—which have important value economically and account for the wellbeing of the ecosystem by providing , a place for leisure, and carbon sinks—we must better understand how trees and forests survive extreme weather caused by global warming.

Once trees encounter strong wind turbulence exceeding their stability, they fail. Strong winds cause forest damage, but not all trees are uprooted or broken on the stem. To date, the mechanism by which trees fail has been believed to be caused simply by pressure from wind turbulence to the canopy, which leads to tree oscillations; subsequently, the accumulated stress causes stem or root failure. This study is a substantial step in reducing the gap between the current understanding and actual forest damage processes by the wind.

Two plots in Sugi tree (Cryptomeria japonica) planted forests were used for this study: unthinned plots that were the control and thinned plots that have a greater distance between trees. The researchers found that the control plot had no damage while the thinned plot had some damaged trees. The undamaged trees in the thinned plot, however, were leaned, never returning to their original vertical positions. All trees in both plots should have received similar pressure from wind turbulence at the same time; why, then, did some trees survive and not others?

The trees in this study were equipped with sensors monitoring stem strains and crown positions. The researchers were able to collect data from both trees that survived and trees that failed. Similarities and differences of the tree oscillations within and between the different plots were analyzed.

Observing the crown sway data of all trees together, Dr. Kamimura realized that the trees in the control plot helped each other to release strong pressure by frequently crushing their crowns, whereas the trees in the thinned plots had to individually resist the pressure without any help from the neighboring trees, due to the distance between the trees. In other words, the control plot built resilience together and the trees in the thinned plot had to resist strong pressures alone. This answers the frequently discussed question of why trees in forests immediately after thinning are more vulnerable to . The thinning makes the distance between trees greater, which transforms forests into a collection of single trees by reducing the chance of crown collisions that act as a buffer of energy transfer to the roots.

How the trees are spaced changes the likelihood of tree survival because of the different levels of support provided by neighboring . Tree spacing can be controlled through ; thus, forest damage risk can be reduced even under climate change conditions.

Further research of diverse forest settings would bring more clues as to how forests have survived millennia and what people can do for forests under changing climates.

“Tree dynamic response and survival in a category-5 tropical cyclone: The case of super typhoon Trami” is published in Science Advances.



More information:
Kana Kamimura, Tree dynamic response and survival in a category-5 tropical cyclone: The case of super typhoon Trami, Science Advances (2022). DOI: 10.1126/sciadv.abm7891. www.science.org/doi/10.1126/sciadv.abm7891

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Hexbyte Glen Cove Record heat, forest fires in Colombia’s Amazon in January

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Aerial view of the Putumayo River in Colombia’s Amazon rainforest, in the Putumayo region on November 6 2021.

January of this year was the hottest month in the Colombian Amazon in a decade, leading to an increase in forest fires in the southeastern region and very likely impacting air quality in the capital Bogota, according to an Environment Ministry report seen by AFP Friday.

It said the month of January recorded the “highest hot spot values in the last 10 years” in the Colombian Amazon.

The phenomenon occurs, the ministry said, when the country goes through a season of low rainfall, and is due to “anthropic activities,” that is to say human activities, of which “the most important is associated with deforestation fronts.”

At least 80 percent of the “hot spots” were , a ministry spokesman told AFP. At the end of January, the ministry identified more than 3,300 “hot spots” in the six departments that make up the Colombian Amazon, including 1,300 in the Guaviare region alone.

According to testimonies collected by AFP in October in the region, peasants and landowners take advantage of the dry season, from January to April, to burn or cut down trees and plant coca plants in their place, or to let cattle graze there.

The Serrania del Chiribiquete National Park, listed as a UNESCO World Heritage Site, is particularly threatened, as is the Nukak National Nature Reserve, a vast territory of jungle inhabited by the last nomadic indigenous people of Colombia.

The Foundation for Conservation and Sustainable Development (FCDS), which keeps its own count and regularly flies over the areas concerned, recorded at least 938 fires, the highest monthly January figure since 2012.



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Record heat, forest fires in Colombia’s Amazon in January (2022, February 5)
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Hexbyte Glen Cove Forest fires in Bolivia consume vast area: official thumbnail

Hexbyte Glen Cove Forest fires in Bolivia consume vast area: official

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Firefighters try to extinguish a grass fire near the Viru Viru airport in Santa Cruz, Bolivia on August 1, 2021; the department has been hard hit by forest fires.

Forest fires this year have consumed more than 147,000 hectares (360,000 acres) in Bolivia’s eastern Santa Cruz department, the regional government reported Saturday.

As in neighboring Brazil, the fires have been aggravated by widespread deforestation aimed at expanding farming or pasture land.

And they come in a year when has become an increasingly urgent issue with mammoth wildfires in the Western US as well as in Greece and Turkey.

“At a departmental level, 147,254 hectares have been affected by ,” Yovenka Rosado, coordinator of Santa Cruz’s Forest Fire Program, announced.

The most severely affected areas border Brazil.

Rosado said a Super Puma helicopter was being used to douse the larger fire sites with water, and and equipment were being deployed to key spots.

Rosado said 831 fires had been reported just in the first days of August, for a total this year of 15,555.

Each year Bolivia confronts forest-fire outbreaks started by settlers in or by agribusinesses trying to expand their production.

Bolivian NGO the Friends of Nature Foundation estimates that forest fires last year destroyed more than 2.3 million hectares of forests and grassland.

In 2019 huge fires in Bolivia’s Amazon destroyed about 6.4 million hectares, the group said.



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Forest fires in Bolivia consume vast area: official (2021, August 8)
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