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Nitrogen-fixing plants are most diverse in arid regions of the United States of America, noted a new study.
The results were surprising as the nitrogen-fixers generally lack the traits associated with arid soils, such as the thick water-storing stems of the cactus, according to the study published in the journal Global Ecology and Biogeography May 28, 2022.
“At first glance, nitrogen-fixers don’t necessarily appear to be adapted for arid ecosystems,” said Joshua Doby, lead author of the study.
The reason for this strange pattern wasn’t evident, but it may have something to do with how nitrogen-fixers and non-fixers utilise the element, Doby added.
The findings contradict the widely accepted belief that nitrogen-fixers are more diverse in soil with limited nitrogen.
The researchers focused on the variety of native nitrogen-fixers. Regardless of the amount of nitrogen in the soil, arid regions have shown a stark increase in the diversity of native nitrogen-fixers.
Researchers from the Florida Museum of Natural History, Louisiana State University and Mississippi State University analysed records for native and invasive species from more than 40 sites across the US, using data from the National Ecological Observatory Network.
The researchers suspect whether these plants can survive climate change-induced global warming. They fear that the conditions that support diverse floras in the arid region may not sustain for a longer period. These adaptive traits may not ultimately save them.
“As things become wetter and warmer due to climate change, the traits that made these plants well-adapted and diverse aren’t going to be very beneficial anymore. Many of the unique plant communities we have around today are going to be at risk in the long term,” said Doby
Why is nitrogen fixation important?
Nitrogen-fixation involves converting atmospheric nitrogen into its more reactive constituents, such as — nitrates, nitrites, or ammonia.
These compounds support agriculture and plant growth. On the contrary, a lack of nitrogen stunts the growth of crops. About 90 per cent of the biotic nitrogen is fixed by microorganisms present in the soil.
Legumes such as — pea, broad bean, soya bean, clover and cowpea are the best-known nitrogen-fixing plants. They team up with rhizobium bacteria to fix the atmospheric nitrogen. Lightning also contributes to nitrogen-fixation.
Sangu pushpam (butterfly pea flower), fenugreek and agathi keerai (vegetable hummingbird) are some nitrogen-fixing plants that can be grown in home gardens.