Mangroves’ shiny leaves and branching root are stunning. Now, a study shows that the moon plays a significant role in the health of these trees.
Long-term tidal cycles Set in motion by the MoonResearchers report that mangrove forest expansion and contraction in Australia is driven in large part by climate change, as reported in the Sept. 16 issue. Science Advances. This discovery is crucial in predicting the time when mangroves will reach their maximum potential for sequestering CO2. Could help combat climate changeThese are the most likely to proliferate.SN: 11/18/21). This knowledge could be used to improve the conservation and restoration of forests.
Mangroves are trees along the coast that support a variety of plants called mangroves. Protect the environment and provide habitat for fish (SN: 9/14/22). However, forests in certain areas are vulnerable to a variety of threats including pollution, coastal development and agricultural land clearing. To get a bird’s-eye view of these forests, Neil Saintilan, an environmental scientist at Macquarie University in Sydney, and his colleagues turned to satellite imagery. The researchers used NASA data and U.S. Geological Survey Landsat data between 1987 and 2020 to calculate how mangrove forest size and density has changed over time.
After accounting for persistent increases in these trees’ growth — probably due to rising carbon dioxide levels, higher sea levels and increasing air temperatures — Saintilan and his colleagues noticed a curious pattern. Mangrove forests had a tendency to contract and expand in predictable ways. “I saw this 18-year oscillation,” Saintilan says.
Researchers were intrigued by this regularity and began to think about the moon. Earth’s nearest celestial neighbor has It has been long known that the tides are driven by themThese are the ones that provide water and nutrients for mangroves. A rhythm called the lunar nodal cycle could explain the mangroves’ growth pattern, the team hypothesized.
Over the course of 18.6 years, the plane of the moon’s orbit around Earth slowly tips. When the moon’s orbit is the least tilted relative to our planet’s equator, semidiurnal tides — which consist of two high and two low tides each day — tend to have a larger range. Semidiurnal waves are more common in areas that have high tides that are higher than those that have lower tides. This is due to the angle at which gravity pulls the moon on the Earth.
Saintilan and his colleagues found that mangrove forests experiencing semidiurnal tides tended to be larger and denser precisely when higher high tides were expected based on the moon’s orbit. The effect even seemed to outweigh other climatic drivers of mangrove growth, such as El Niño conditions. The team suggests that other mangrove-rich regions such as Vietnam or Indonesia may also experience similar long-term trends.
Saintilan claims that this discovery was possible because of the availability to data dating back many decades. “We’ve never really picked up before some of these longer-term drivers of vegetation dynamics.”
It’s important to recognize this effect on mangrove populations, says Octavio Aburto-Oropeza, a marine ecologist at the Scripps Institution of Oceanography in La Jolla, Calif., who was not involved in the research.
Aburto Oropeza says scientists now know when certain mangroves will flourish, and that they should be promoted at these times. He says that this could be seen as an increase in human activity near the forest, which could lead to damage. “We should be more proactive.”
