Some tree leaves will fall 3-6 days in advance by end of century due to climate change: Study
Berlin: A large-scale study of European trees suggests that the leaves of trees between the tropics and the polar regions of the Earth will start to fall in advance by three to six days by the end of the 21st century rather than lengthening by one to three weeks as current models have predicted.
The scientists, including those from the University of Munich (LMU) in Germany, said earlier studies had predicted that the shedding of leaves from these temperate trees will get later under the ongoing climate crisis.
They said early observations also supported this idea since warming caused leaves to stay on the trees later over recent decades, driving increased growing season length that could help to slow the rate of climate change.
However, the current study, published in the journal Science, showed that this trend might be reversed as increasing photosynthetic productivity begins to drive earlier autumn leaf fall or senescence.
According to the researchers, the results build on growing evidence that plant growth is limited by the ability of tree tissues to use and store carbon.
While changes in the growing-season lengths of temperate trees greatly affect global carbon balance, they said future growing-season trajectories remain highly uncertain since the environmental drivers of autumn leaf senescence are poorly understood.
Autumn leaf-shedding at the end of the growing season in temperate regions is an adaptation to stressors, such as freezing temperatures, the scientists explained.
While a common assumption is that alleviating a warmer climate could allow leaves to persist longer and consume more atmospheric carbon, the researchers said the role of photosynthesis in governing the timing of leaf senescence has not been widely tested in trees.
In the current study, the scientists used long-term observations from dominant Central European tree species from 1948 to 2015, and experiments designed to modify carbon uptake by trees, to evaluate related impacts on senescence.
"Accounting for this effect improved the accuracy of senescence predictions by 27 to 42 percent and reversed future predictions from a previously expected 2- to 3-week delay over the rest of the century to an advance of three to six days," the scientists wrote in the study.
The data revealed that increased growing-season productivity in spring and summer due to elevated carbon dioxide, temperature, or light levels can lead to earlier -- not later -- leaf senescence.
This is likely because roots and wood cease to use or store leaf-captured carbon at a point, making leaves costly to keep, the study noted.
The model built by the researchers forecasted the possibility of slight advances, no delays, in autumn leaf-dropping dates over the rest of the century.
According to the scientists, the results "substantially lower our expectations of the extent to which longer growing seasons will increase seasonal carbon uptake in forests".
However, they said the universality of this pattern in other forest types remains unknown.
The researchers believe it is important to implement such growing-season length constraints in other models that do not consider these dynamics.
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Trouble ‘Miyas’ everywhere only then they will leave Assam: Himanta Biswa Sarma
Says “Himanta Biswa Sarma, BJP are openly against them, we are saying it openly
New Delhi: Assam Chief Minister Himanta Biswa Sarma on Tuesday said that four to five lakh “Miya voters” would be removed from the electoral rolls in the state once the Special Intensive Revision (SIR) of voter lists is carried out. He also made a series of controversial remarks openly targeting the Miya community, a term commonly used in Assam in a derogatory sense to refer to Bengali-speaking Muslims.
Speaking to reporters on the sidelines of an official programme in Digboi in Tinsukia district, Sarma said it was his responsibility to create difficulties for the Miya community and claimed that both he and the BJP were “directly against Miyas”.
“Four to five lakh Miya votes will have to be deleted in Assam when the SIR happens,” Sarma said, adding that such voters “should ideally not be allowed to vote in Assam, but in Bangladesh”. He asserted that the government was ensuring that they would not be able to vote in the state.
The chief minister was responding to questions about notices issued to thousands of Bengali-speaking Muslims during the claims and objections phase of the ongoing Special Revision (SR) of electoral rolls in Assam. While the Election Commission is conducting SIR exercises in 12 states and Union Territories, Assam is currently undergoing an SR, which is usually meant for routine updates.
Calling the current SR “preliminary”, Sarma said that a full-fledged SIR in Assam would lead to large-scale deletion of Miya voters. He said he was unconcerned about criticism from opposition parties over the issue.
“Let the Congress abuse me as much as they want. My job is to make the Miya people suffer,” Sarma said. He claimed that complaints filed against members of the community were done on his instructions and that he had encouraged BJP workers to keep filing complaints.
“I have told people wherever possible they should fill Form 7 so that they have to run around a little and are troubled,” he said, adding that such actions were meant to send a message that “the Assamese people are still living”.
In remarks that drew further outrage, Sarma urged people to trouble members of the Miya community in everyday life, claiming that “only if they face troubles will they leave Assam”. He also accused the media of sympathising with the community and warned journalists against such coverage.
“So you all should also trouble, and you should not do news that sympathise with them. There will be love jihad in your own house.” He said.
The comments triggered reactions from opposition leaders. Raijor Dal president and MLA Akhil Gogoi said the people of Assam had not elected Sarma to keep one community under constant pressure. Congress leader Aman Wadud accused the chief minister of rendering the Constitution meaningless in the state, saying his remarks showed a complete disregard for constitutional values.
According to the draft electoral rolls published on December 27, Assam currently has 2.51 crore voters. Election officials said 4.78 lakh names were marked as deceased, 5.23 lakh as having shifted, and 53,619 duplicate entries were removed during the revision process. Authorities also claimed that verification had been completed for over 61 lakh households.
On January 25, six opposition parties the Congress, Raijor Dal, Assam Jatiya Parishad, CPI, CPI(M) and CPI(M-L) submitted a memorandum to the state’s chief electoral officer. They alleged widespread legal violations, political interference and selective targeting of genuine voters during the SR exercise, describing it as arbitrary, unlawful and unconstitutional.
