Redwood trees have two types of leaves, scientists find – a trait that could help them survive in a changing climate

Coast redwoods are extraordinary trees that scientists have studied over the years. We know they’re there. The tallest living treeThey have survived for millennia. Refrain from setting fire to yourself Pests. Redwoods are long-lived and large, and they resist decay. This is why they dominate the forest. More above-ground mass and therefore more carbon, than any other eco-system on Earth.

However, while I was working on a newly published study, my colleagues at the University of California, Davis, Cal Poly Humboldt IUnbeknownst to us, we discovered a hidden secret.

Redwoods have two types of leaves. They look very different and perform very different tasks. This previously unknown feature helps the trees adapt to both wet and dry conditions – an ability that could be key to their survival in a changing climate.

Just enough water

Every tree grows sooner or later, and their leaves become wet. Trees in wet environments can have problems if they are covered with water. Cover their stomata. These tiny pores allow carbon dioxide into the leaves, allowing it to combine with water to create plant tissue. photosynthesis. Many trees are common to wet forest have leaves with adaptations. Stop these water films forming.

Trees that grow in dry environments, on the other hand, can take advantage of short periods of leaf wetness. Get water!directly across their leaves’ surfaces Through the use of special leaf structures, and even Through their stomata. Some trees, like coast redwoods live in both wet or dry environments with intense seasonal variation.

For broad-leaved tree like the Holm oakThis seasonal wetness challenge, which is common in Mediterranean climates that have dry summers and rainy springs, is relatively simple to overcome for the, which grows in Mediterranean regions with dry summers. Their stomata are on the sheltered undersides of their leaves, which keeps them clear of water, while the leaves’ top surfaces absorb water. Redwoods, also known as cone-bearing trees or conifers, are conifers. A thin, flat needleLeaves have to be able to absorb and repel water in a different way.

We knew that we wanted to investigate how redwoods cope with the paradoxical challenge presented by leaf wetness, how redwoods can absorb water and which leaf features could affect their water uptake capacities. It was a complete surprise to discover what we discovered.

Big trees, big secrets

Scientists have long known about redwoods’ Ability to absorb water through their leaves. It is difficult to determine how much water redwoods can absorb and how this capacity might differ from one climate to the next.

First, a redwood tree has more than 100,000,000 leaves. Huge surface areaWater absorption These leaves Structures can be drastically altered by increasing in heightIt can be either long and flat or short and awllike. So we couldn’t get this right by simply picking leaves at ground level.

To complicate matters further, gravity is always pushing down on the giant column of water rising upward through a redwood’s trunk. The result is that leaves at the top end of the tree are not as tall. Always have less water availableThey are more valuable than those at the bottom. The treetop’s inherent dryness should pull water into the leaf more quickly than into water-rich leaves at the bottom, just as a dry sponge picks up water faster than a damp one.

To get a true picture of redwoods’ ability to absorb water, we needed leaves from trees from both wet and dry environments. We also needed leaves from trees at different heights. We put the leaf samples into a water bath to get them to their natural gravity-based water levels. fog chamber – in this case, an ice chest hooked up to a room humidifier – and measured weight gain over time to see how much water they could absorb.

A trail of clues

Each cluster of redwood shoots was taken apart to be submerged in fog. We then divided them into pieces. Redwood shoot clusters are made from a woody core. Each shoot has its own set of leaves and is separated into separate shoots. We separated shoots. The central woody axisThe softer, more common pliable shots are found at the outer edges each cluster.

It became apparent quickly that the leaves of the shoots in the center axis could absorb water three times faster that those of the peripheral leaves. We discovered that the leaves were of two distinct types when we examined them with a microscope. They don’t look the same on the outside either, but this was so unexpected that we needed to see their internal structure to really convince ourselves.

The axial leaves were packed with water storage cells, but their phloem – tubes in the leaves that export photosynthetic sugars to the tree – appeared to be blocked and useless. We were not sure if the axial leaf served a different purpose.

With some additional measurements, we found that redwoods’ axial leaves are specialized for absorbing water. The differences in water absorption rates between axial and peripheral leaves are due to differences in the wax coverage and surfaces.

Unlike the axial leaves, redwoods’ peripheral leaves have waxy surfaces with lots of stomata. This helped to explain why they were so beautiful. Photosynthesize all yearRegardless of the wet season in their current habitat.

Further analysis showed that the redwoods’ axial leaves account for only about 5% of the trees’ total leaf area, and barely produce enough energy through photosynthesis to maintain themselves. But they contribute up to 30% of the trees’ total water absorption capacity. These two types of leaves are able to balance the dual requirements of photosynthesis as well as water absorption, allowing redwoods thrive in both dry and wet habitats.

Large-scale use Measurements of trees Here are some equations to estimate the redwood leaf surfaceWe found that these thirsty giants can take in as much as 105 lbs (48 kilograms) of water as soon as there is a heavy rain. That’s equivalent to 101 pints of beer.

Redwoods’ significance

Understanding what causes the variation in redwood leaves’ uptake capacity can help us gauge differences in water uptake capabilities among trees and environments, now and in the future. This is, in my opinion, the most important part of our research.

Redwoods adapt their two leaf types to their local climates. The trees in the northern part, above Mendocino County’s wet rainforests, invest less in the axial leaves that are designed to absorb water. These leaves are concentrated in the trees’ lower crowns, leaving the photosynthetically High-performing treetopsYou can maximize sugar production in bright sunlight.

In dry forests on the southern margins of redwoods’ range, trees have more axial leaves in their water-stressed tops. This allows them to benefit from shorter leaf-wetting events but also means that they photosynthesize less per area than redwoods in wetter areas.

Redwoods’ ability to shift leaf types to match regional climatic differences may help them adjust to climate change in an ever-drier California. This would be good news to conserve these magnificent trees, and it could be a promising feature for scientists to investigate. Link drought tolerance traitsRedwood populations vary in their regional distribution.