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Forest spiders reveal the hidden cost of 'useful' sunlight.

The article "Forest spiders reveal the hidden cost of 'useful' sunlight" first appeared on the AZ Animals website.

In Germany, conservationists, land managers, and scientists are conducting a bold experiment in biodiversity conservation. Instead of creating uniform forests of trees of the same age, they have begun clear-cutting sections of the forest, leaving dead wood behind, hoping to allow sunlight to reach the surface and create new habitats for diverse species. It's a shining example of the effectiveness of this method in conservation science. However, a new study has identified one group of species that suffers from such disruptions: spiders.

<p> The common striped spider is found in European forests.</p><p> ©iStock.com/Ines Carrara</p><p> » loading=»lazy» width=»960″ height=»640″ decoding=»async» data-nimg=»1″ class=»rounded-lg» style=»color:transparent» src=»https://s.yimg.com/lo/mysterio/api/1f20f364ed1c7b4b791bb3040f610bce21609a4851fb94cb29ca7528f79d5ffa/lightyear_networkapi/resizefill_w96 0;quality_80;format_webp/https:media.zenfs.comena_z_animals_articles_59845c4baa440e3728279b0dbae0bf25142″&gt;<figcaption><p> The common striped spider is found in European forests.</p><p> ©iStock.com/Ines Carrara</p></figcaption></figure><h2> Why dark forests foster spider diversity</h2><p> For spiders, dense forests with closed canopies offer a variety of ecological niches and hunting opportunities. Wolf spiders and jumping spiders scurry and stalk their prey along the forest floor; ground-dwelling sac spiders build web-lined tunnels in the soil and among leaf litter. Orb-weaving spiders spin silky, sticky webs to catch flying insects in the undergrowth and between tree branches. Spiders that hunt in the tree canopies, such as some species of crab spiders, camouflage themselves among leaves to ambush their prey. Thus, a dense, continuous forest can be home to a wide variety of spider species.</p><figure><figcaption><p> Tree-dwelling jumping spiders (Phidippus otiosus), like this one, specialize in hunting near the treetops.</p><p> ©Andres Molin / CC BY-SA 4.0 – Original / License</p></figcaption></figure><p> A study conducted by Jean-Léonard Stöhr and Julia Rothacher of the University of Würzburg covered 11 sites in German forests. The researchers compared experimental sites modified with various combinations of stumps, logs, or standing dead trees with control sites consisting of dense forest. A total of 234 pitfall traps were set up at the sites, and by the end of the study, 18,000 spiders from 206 different species had been collected, representing one-fifth of Germany&#039;s spider diversity.</p><p> Spiders help maintain forest health by regulating insect populations, especially leafhoppers and moths, which pose a particular threat to trees. Spiders can even influence the rate at which leaf litter decomposes into the soil by preying on decomposing organisms (or on the predators of these organisms). By preying on insects such as mosquitoes and ticks that can spread pathogens, a healthy spider population can slow the spread of diseases. Spiders are important prey for birds, bats, reptiles, amphibians, and other animals. Some birds even use their webs to build nests.</p><figure><figcaption><p> Crab spiders (genus <em>Misumena</em> ) take advantage of openings in the tree canopy as they prey on flowering plants that thrive in direct sunlight.</p><p> ©Nenad Nedomacki/Shutterstock.com</p></figcaption></figure><p> The study found that untreated plots, used as control sites in the experiment, had the highest spider biodiversity due to the large number of ecological niches available to spiders in dense forest. Interestingly, plots with more tree clearing had the highest spider abundance but lower species diversity. Sunlight penetrating the forest floor promotes the growth of grasses and flowering plants, which attract butterflies and pollinators. This provides an advantage to spiders that hunt by ambush or stalk their prey, such as crab spiders and wolf spiders. On the other hand, spiders that use webs to catch prey may be at a disadvantage.</p><h2> The benefits of turning forests into &quot;polluted&quot; areas</h2><p> More than half of the forests in the Northern Hemisphere are actively managed for reasons such as fire control, erosion prevention, and, of course, timber production. While growing just a few tree species in close proximity across an area may ensure easy harvesting, it does not promote biodiversity. By leaving stumps and dead wood on the forest floor, preserving standing trees, and logging areas instead of clear-cutting, land managers can create a heterogeneous landscape that provides niches for a wide variety of species.</p><figure><figcaption><p> Approximately 75% of European forests are even-aged stands suitable for timber harvesting.</p><p> ©ronstik/Shutterstock.com</p></figcaption></figure><p> Forested areas support a greater diversity of understory plant species and, as research has shown, promote a diversity of birds, bees, and hoverflies. As we learn more about how interventions affect forest biodiversity, land managers and local communities can better develop plans to promote healthy forests: after all, a more biodiverse forest is a more resilient and productive forest.</p><p> These results may be good news for spider biodiversity in particular. While measures promoting diverse ecological niches in managed forests are popular and have helped protect rare and endangered species, dense vegetation with a closed canopy is a classic characteristic of forests in Europe and beyond.</p><p> The article &quot;Forest spiders reveal the hidden cost of &#039;useful&#039; sunlight&quot; first appeared on the AZ Animals website.</p>&lt;div class=

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