It is easy to look at a forest and you may think it necessary: the trees have arisen through the seasons and the magnificent processions of the seeds and the earth, and they will replenish themselves as long as the environmental conditions are tolerated.
Hidden from the eyes are the creatures whose work makes the forest possible, the multitude of microorganisms and invertebrates involved in maintaining that land, and the heavy animals that carry the seeds that the winds sprout into places.
If we are looking into the future of the forest – which tree species will flourish and which will decline, whether they will successfully migrate to new host lands in the face of rapid climate change – we must look to these animals that scatter seeds.
“All the oaks that try to move north are trying to trace a habitable range,” Ivy Ven, a biologist at the University of Maine, who could be found one recent afternoon at the Penobscot Experimental Forest in Milford near Milford.
“The only way to deal with the fluctuating temperatures is to move with the animals,” Ms. Come from the trees, he said. “Does personality affect it? Will there be any people who will be more helpful?”
Ms. Vena is a doctoral student in the lab of Alessio Mortelliti, a wildlife ecologist who has been in Genoa for nearly a decade with a particular interest: how to cut the seeds scattered with the study of emerging animal personalities.
Although researchers had already investigated the ways animals seed across landscapes, aspects of their possible personalities were largely unexplored. The Penobscot Experimental Forest, with its 1,800 acres of closely monitored forests treated with a variety of forestry techniques, provides a field environment for exploring this question.
Every summer for the past seven years, students of Dr. They killed deer mice and southern voles in their study of the machines — they included about 2,000 animals in all — and ran them through tests to measure where they fall on a spectrum between bold and timid. . Before being released, each one will be tagged with a microchip, not unlike those used to identify lost pets.
The tags trigger sensors, like the Ms. Ven had mounted above her a lance of bullets. Each acorn was painted with colored ribbons, to indicate its species: red oak, holly, black oak, white oak, white oak, red oak, pin oak, willow oak. Red oak is already abundant in the region, but other species have only recently arrived or are expected to, as the eastern heatwaves push their ranges north.
Whether these trees succeed in this slow movement of migration — and ultimately thank the new landscape with its noble, carbon-separating, sheltering, wildlife-feeding presence — will be a function of countless battles between the mouse or the fly and the bullet.
Does the animal take the nut? If so, did I eat the nut right away or was it saved for later? Where does the animal cache go? How often do they not return, either because they forget the place or, as often happens, so that in the forest hungry predators bite the full-sized animals, because they are eaten first, giving the bullet a chance to germinate?
“They see the forest regenerating,” Dr. Mortelliti said. “But what people don’t see is that the forest is regenerating according to the decisions of small mammals.”
In the areas of study Dr. Mortality is documented in both such encounters. Like a mouse or a fly to a lance; the sensor reads the microchip, identifying the animal; the motion activated camera captures the moment, the memory of which they received the nut. Over this time, Ms. Ven said he fired more than 1,800 bullets.
On this autumn night, Ms. Ven landed five dishes, each about 100 feet apart. Around each individual scatters a nontoxic fluorescent dust that temporarily sticks to visitors’ feet. When he returned before dawn, equipped with an ultraviolet lamp under which the dust glowed, small traces of signs surrounded each tray and dragged him into the darkness.
People don’t realize how many rats and flies there are, Ms Ven said. He estimated that every 13 steps he took on his way to a place, he passed a mouse or a fly – not in the open, but hiding under a leaf or a nest made in the grass. By the light of the twinkling stars and the claws of the moon, the moles did their quiet work. every bullet had gone.
Each of them followed Ms. Ven one by one. Little tracks shone under his lamp, leading around mossy hummocks and slipping under branches and up to trunks and then running back again. As a mouse walks, it is the opposite of as a crow flies. Others ended up in the cellar – under a hollowed-out root, a rotting log, dug into the ground and their backs carefully covered. Ms. Vena marked the last spots with small golden flags.
Some of the bullets, which were stored for the future winter, were intact. Others were taken away, but from fragments of painted shells Ms. Twenty species are identified. With the help of Elizabeth Pellecer Rivera, a graduate research assistant, she made notes about each. Sensor data and camera records will later show a lot of collection made by one particularly industrious deer mouse known to researchers as 982091062973077, a 13-gram male captured in late September and revealed through tests quite timidly, although with a cautious exploratory series.
When the time winds down, Ms. Come, Dr. Mortelliti and two of her students, Maisie Merz and Brigit Humphreys, are solving all this data and looking for patterns.
Perhaps certain personality traits will prove more appropriate than others for choosing certain oak trees. It is possible for the most daring rodent to lift a heavy bullet to its paw, then stagger under the weight, vulnerable to predators, until it finds a hiding spot. Perhaps the more timid rats hide them in the most suitable places to germinate the forgotten nut.
The results will add to the process of studies arising from the experiment over the past several years, most of which Allison Brehm, Dr. Mortelliti was the doctor’s first doctoral student and the person who taught Ms. Ven to investigate.
In a 2019 study in the Ecological literature, which Dr. In what Mortelliti described as a “proof of concept,” the researchers showed that the personalities of small mammals influence seed selection. Earlier this year, the team described how some deer mice, depending on their personality, were more likely than others to cache red oak, white pine and American beech nuts in ways that promote sprouting.
Conversely, the foraging patterns of personality-specific rodents changed when predators were around, researchers showed in a 2021 Oikos paper.
And land use changes these movements. For example, a 2019 study found that in areas that had started years before, small mammals tended to be bolder. A study the following year revealed that more natural forests, with a mixture of habitats rather than the uniformity that most commercial logging fostered, contained a greater diversity of personality.
“This diversity of individuals is maintained in populations because it is good, just as genetic diversity is good,” Dr. Brehm said.
Rafał Zwolak is an ecologist at the Adam Mickiewicz University in Poland who studies seed dispersal and animal personality., He called the research “absolutely pioneering.”
“I hope their work will encourage researchers in other labs, working in other ecological systems, to focus on this area,” he said.
Asked to define the practical implications of his research, Dr. Mortelliti said: “Keep the diversity of personalities.” There is no one ideal person; but different people play different roles. Depending on the circumstances – drought, natural disturbances, fluctuations in predator populations – different personality traits can be predicted. Some of these dynamics do not preclude the cutting of timber, said Dr. Brehm, however, argues for caring.
“If you have to rule the field, you don’t want to rule the same way,” he said. “You want to manage different parts differently as a heterogeneous landscape.” Techniques can be used that preserve different species, ages and sizes of trees, trying to imitate what would happen naturally.
Many things remain undeveloped, noted Dr. They died. Modes of shyness and boldness are not the universality of the animal’s personality; they are just according to nature and easy to measure in the field. The oak wanders behind hundreds of other plant species, each following its own animal-mediated trajectories.
As Ms. Ven the work was done, and the preceding night gave way to dawn. The blue arrow is called; the squirrel turns red. Both are seed dispersers with personal contributions that affect the forest. The same can be said of bears, foxes, crows, turtles, and even ants, the whole body of which has not yet been explored, affecting not only plants, but also fungi.
“I’m only looking at two species at night,” Ms Ven said. “It’s a very small snapshot of what’s going on.” The full picture may not emerge for decades, but the features are already clear: It has many personalities to awaken the forest.