Trees compete for space, light and resources, and these clashes can leave battle scars

When you walk through a forest, it could appear to be a static environment where little or no is occurring. But trees are always interacting and reacting to one another as they grow. There is intense competition for light and space, and any change affects the general composition of the forest ultimately.

Forest scientists like me spend loads of time fascinated with it Forest succession – a predictable process by which plant species colonize and dominate a bit of land. The basic sequence is that the land develops from an open field to scrubland and shrubs, then to young trees, and at last to large, mature trees. Disturbances akin to a severe storm or forest fire can interrupt or delay forest succession.

I study ecological changes in species composition, tree arrangement and forest development that occur during succession and after disturbances. My research team analyses conditions in mixed-species deciduous forests. Using tree rings, we reconstruct what former forests looked like years ago.

By applying observed patterns and processes, researchers can model the longer term growth and evolution of forests. Here are some insights into what might occur among the many trees around you as you’re taking a forest walk.

Battle for space and lightweight

Forest communities are made up of trees of various species, sizes and styles. Each species requires a certain amount of sunlight and space to thrive and grows at its own rate.

Many trees distance themselves from other trees to reduce interaction with their neighbors – a pattern researchers call crown shyness. If you look up, chances are you’ll notice gaps between trees and branches near the gaps with broken branches and fewer leaves. In contrast, branches and leaves which have adequate space and sunlight to grow are denser and healthier.

Mixed deciduous forests often support greater than 30 species of treeswhich suggests they will develop in many alternative ways. By understanding how trees interact, forest managers, whether rural or urban, can establish practices that control forest growth.

When a forest is just beginning to emerge, it may well have hundreds of tree seedlings per hectare. But only 50 to 100 trees per hectare can survive and grow up. Foresters are working to find out which trees are displacing other trees and which trees are giving up growing space.

One of an important zones for understanding forest growth is the cover – the forest cover, which incorporates all of the leaves, branches and twigs within the tree crowns. A typical mixed forest has several cover layers consisting of species with different growth rates. When trees die, they release growth space that surviving trees use by growing and expanding their canopies.

How storms shape the forest

A mature tree can be exposed to many weather events during its life. Storms force trees to sway and bump into their neighbors, causing crown abrasion – damage to buds and branch suggestions. These effects can Slowing down and reducing branch growthCrown wear is an indication that the tree population is simply too dense and competition amongst trees is undermining healthy growth.

However, crown abrasion can actually help some species. For example, oaks, a slower-growing species, have dense tissue and powerful branches that may abrasive and damage branches of faster-growing trees akin to poplars and rubber trees, whose wood is weaker and fewer dense. This allows oaks to outcompete their initially faster-growing competitors.

Some forests are monocultures, with just one species of tree. In large parts of the western United States, for instance, forests were burned or cut down within the nineteenth century and later replanted with Lodgepole pinenative to western mountain regions. The trees all grew back at the identical rate, unlike in mixed forests where some species grow faster than others.

This resulted in tall, slender trees that fluctuate more in windDue to crown abrasion or crown shyness, the pines have small crowns that don’t expand laterally so far as normal.

These forests eventually stagnate. The distance between the trees shrinks since the small crowns of the trees don’t keep neighboring trees at arm's length. Tree growth decreases and The vitality of the trees is decreasing.

Thinning of those forests or the implementation prescribed fires can increase the space between trees and supply extra space for crown growth.

Watching the trees fight

To study the movement of branches in wind, my students and I exploit accelerometers – devices that measure how quickly the speed of a moving object changesMost modern smartphones contain built-in accelerometers Apps like Google Maps help determine the phone's location.

We attach the accelerometers near the ends of the branches, where they measure the movements of the branches in three dimensions. By combining this data with real-time wind speed measurements, we are able to determine the movements and acceleration of the branches in response to different wind speeds.

In one study, we examined how interactions between different tree species altered the forest cover in riparian forests along rivers and streams in central Mississippi. These forests consisted primarily of Cherry bark oak And Sweetgum treesBoth species are common in mixed stands, but have different crown shapes and growth rates.

At first, sweetgum trees were more quite a few and distinguished in young forests. But over time, because of the abutting trees, cherry oaks began to achieve strength within the spaces left by rubbed sweetgum branches. Eventually, the oak displaced the declining sweetgum and got here to dominate the forest cover.

Leadership from top to bottom

The forest environment is always changing and is influenced by many aspects, from insect invasions and plant diseases to climate change and natural disasters. Physical cover wear amongst species will not be as well understood as a few of these other pressures, but clearly contributes to the event of diverse mixed-species deciduous forests.

Our research suggests that when crown wear reduces the crown size and growth of faster-growing species, slower-growing, more vigorous species can emerge and prevail. These findings might help scientists and foresters develop and manage healthy, productive forests.