Understanding the critical limits of plants could help save them

Plants play a pivotal role in our ecosystem, but many are at risk of extinction due to increasing challenges like droughts and wildfires. 

A new study by botanists from UC Riverside highlights the urgency to identify the conditions that lead plants to their demise. By understanding these triggers, we can improve conservation efforts.

Critical stress limits 

In a paper recently published in the Oxford Academic journal Conservation Physiology, the UC Riverside team emphasizes the importance of discerning the exact point beyond which a plant’s vital functions cease. 

According to study co-author Professor Louis Santiago, it’s crucial to identify the amount of water loss a plant can endure before wilting and the temperature at which photosynthesis stops for various plants.

“It is so important to measure the critical limits of when things will fail, and not just how they’re doing now,” said Professor Santiago.

The paper reveals an alarming reality: while there are about 700,000 plant species on our planet, the critical stress limits are only known for about 1,000 of them. 

Fatal exposure

Although plants might occasionally recover after surpassing their limits – just like houseplants bounce back after wilting from insufficient water – consistent exposure can be fatal. 

“Wilting, what we refer to as losing turgor pressure, is not always fatal but it’s one step toward death,” said Professor Santiago. “Just like people with extremely high blood pressure might die if they don’t get it to come down.”

Understanding the stress points of a plant, especially with the increasing temperatures and altered climatic conditions, is more than academic curiosity. It offers a metric showing how close some plants are to local extinction. 

When this data is combined with knowledge about a plant’s current physiological state under stress, limited conservation funds can be strategically utilized, allowing early interventions before the plants show visible signs of stress or deterioration.

Focus of the study 

Santiago’s lab, which primarily focuses on plant physiology, has recently pivoted to studying these critical limits. 

“It started after the last drought when we saw species suffering. We wanted to do these measurements to see if we could have predicted the die-offs that we saw,” said Santiago.  

For this particular study, the team investigated the wilting points of six Southern California chapparal shrubs, including the California lilac and two sage varieties. 

Their findings not only highlight the availability of various means to determine these critical limits, but also highlight how such data can positively impact conservation results.

Collaborative efforts are needed

“Generally, we have the capacity to find the most vulnerable, rare species and focus on them. We have the ability to find which plants are most at risk from climate changes, but it’s going to take a collaboration of plant physiologists, conservation biologists, and land managers.”

Professor Santiago believes that while many plant species might face unfamiliar stressors in the upcoming decades due to climate changes, enthusiasts can still play a part in aiding their survival. He encourages joining native plant societies.

“You can join them in pulling out invasive species, or count numbers of rare organisms, and there are countless volunteer projects,” said Santiago. “Let’s work smarter, and work together.”

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