![]() That’s good news for springtails-and maybe for the climate, too. Instead of springtails, they could be eating more of the intermediate predators, like smaller spiders. What’s going on here? The researchers believe that under warming conditions, the wolf spiders are developing a taste for different prey. But in the warmed plots with high spider densities, the researchers found significantly more of the springtail prey, and less evidence of decomposition of the leaf litter in the soil. This was expected since wolf spiders love to eat springtails. At ambient temperatures, there were fewer springtails left in the high-spider-density plots, and decomposition of leaf litter had happened faster. They counted springtails and mites, measured microbial biomass (fungus and bacteria), and tallied the other tiny animals that could either eat the springtails themselves or serve as alternative food sources for the wolf spiders. (Credit: Amanda Koltz)Īt the end of the study period, the scientists surveyed everything inside the enclosures. These mini-ecosystems were 1.5 meters in diameter and separated all of the regular tundra inhabitants-including belowground animals and fungus-from their surroundings in a space where researchers could manipulate the temperature and densities of spiders. To test the effects of warming on the spider/fungus-eater/soil system, Koltz and her team installed a series of experimental enclosures in an area of arctic tundra in Northern Alaska over two summer seasons. As microbes eat dead plants, they also respire carbon dioxide and methane-powerful greenhouse gases.īetween one-third to one-half of the global pool of soil organic carbon is frozen in Arctic permafrost, currently locked away from decomposers but vulnerable to warming. But decomposition is a double-edged sword for the environment. Some of these nutrients, such as nitrogen, are sought-after fertilizers that enhance plant productivity. When there is a lot more fungal activity, there is faster decomposition.ĭecomposition is usually positive for plants, in that it releases more nutrients to the soil. The spiders eat animals (springtails) that eat fungus if more fungus-eaters get eaten, then fungus grows unchecked. And, in wet tundra, the fungus in the ground largely controls how quickly dead plant matter decomposes and releases its nutrients into the soil and air.Īrctic wolf spiders are thus said to have an “indirect” effect on decomposition. Springtails eat both decaying plants and fungus. It’s this spider snack that connects them to the belowground environment. ![]() “Spiders are not going to save us from climate change, but we found that decomposition is slower under warming when there are more wolf spiders present.”īut they really love to eat Collembola-the small arthropods commonly called springtails. ![]() This type of spider hunts on the ground and can eat almost anything smaller in size, from plant-eating bugs to other predators. They are less than half an inch long, but in a warming future, they might be both larger and more prolific. “But in this case we show that when warming alters those interactions, it can also lead to changes in ecosystem-level processes like decomposition rates.” Larger and larger spiders “We often think about how warmer temperatures might strengthen or weaken interactions between predators and their prey,” says Amanda Koltz, a postdoctoral researcher at Washington University in St. But few studies have explored the larger picture of how these changes will alter not just individual species, but also all of the biological and physical interactions in a given environment. Scientists generally agree that climate change will affect the ways in which animals interact with each other. Their sheer numbers make them one of the important predators on the tundra. There are so many wolf spiders that they outweigh real wolves in the Alaskan Arctic by several orders of magnitude. This could initiate a new cascade of food web interactions that could potentially alleviate some impacts of global warming. Under warming conditions, arctic wolf spiders’ tastes in prey might be changing, research shows.
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