The Ecological Society of America (ESA) presents a roundup of four research articles recently published across its esteemed journals . Widely recognized for fostering innovation and advancing ecological knowledge, ESA’s journals consistently feature illuminating and impactful studies. This compilation of papers explores how rainstorms reshape the trail of environmental DNA in streams, how newcomers to an ecosystem do not always gain an edge from escaping their old enemies, how sagebrush conversion to grassland impacts songbirds and how centuries of frequent fire forged the complex Douglas‑fir forests we see today.
From Ecological Applications:
Even rainstorms cannot wash away nature’s fingerprint
Author contact: Olivia P. Reves ( opr2001@gmail.com )
Analyzing the fragments of genetic material left behind by organisms in water, soil, snow and even the air is a convenient way of figuring out what species are present in a particular location. What remains largely unknown, however, is the extent to which natural processes meddle with the presence of this “environmental DNA” (eDNA). In this study, researchers compared eDNA collected from streams and rivers before and after rainstorms to examine the effect that rain has on eDNA’s presence and detectability in waterways. They found a far greater variety of land-based species were represented in eDNA samples following a storm than beforehand, suggesting that rainfall washes the genetic bits and pieces from the surrounding landscape into nearby waterways. On the other hand, eDNA from aquatic species was largely unaffected by rainfall, indicating that DNA shed by these species is just as readily detectable in streams swollen by rain as under normal conditions. The results suggest that sampling rivers and streams after a storm may be the best time to catch a fuller picture of who is around.
Read the article: Rainfall has contrasting effects on aquatic and terrestrial environmental DNA recovered from streams
From Ecology:
Introduced species do not outrun their foes
Author contact: Karen Zeng ( karen.zeng@unsw.edu.au )
Species new to an area may not have as big of an edge over the locals as previously believed, according to a new study. The review tackled the “enemy release” hypothesis, the idea that introduced species benefit from escaping the predators, pathogens and parasites that plagued them back home. Compiling data from 222 published sources, researchers found that freedom from old enemies does not typically translate to a competitive advantage for the newcomers. Although introduced species often encountered fewer predators and pathogens than they did in their native range — and even fewer than native species face — introduced species still were not more successful overall. And in a surprising twist, more than a third of non‑native species actually experienced more attacks in their new habitats than in their original ones. To complicate matters, the effects were highly variable across organisms, with some (mollusks and fish, for instance) benefiting to a much higher degree than others (such as insects). Altogether, the findings suggest that enemy release is far from a guaranteed boost for newcomers, underscoring the need to rethink how we predict and manage the success of introduced species.
Read the article: How strong is enemy release? A systematic compilation across taxa and approaches
From Frontiers in Ecology and the Environment:
A new tune for sagebrush songbirds
Author contact: Brendan K. Hobart ( bkhobart@wisc.edu )
A living symbol of the Wild West, sagebrush ecosystems are rapidly disappearing due to the expansion of invasive annual grasses. Now, evidence suggests that not only is this climate-driven shift reshaping plant communities throughout the U.S. Great Plains, it is also reshuffling the region’s animal species. Drawing on more than a decade of bird surveys from over 7,000 plots across the sagebrush biome, researchers analyzed nearly 60,000 observations of 40 songbird species to track how bird communities change as grass invasion advances. They observed greater species diversity in grassy areas than in traditional sagebrush — a finding that likely reflects temporary boosts in local diversity as generalist species that can live in grasslands move in before sagebrush specialists fully decline. At the same time, species tied closely to sagebrush habitat already showed signs of stress, with fewer sightings signaling the early stages of potential range contractions. Rather than simply reacting to vegetation change, songbird communities appear to be undergoing their own transformation, becoming increasingly novel and distinct from their pre‑invasion state. By mapping where sensitive species overlap with areas likely to face future invasion, the study also identifies which parts of the sagebrush biome should be top priorities for conserving vulnerable songbirds.
Read the article: Annual grass invasion is transforming the sagebrush biome’s songbird communities
From Ecosphere:
How fire fashioned Douglas-fir forests
Author contact: James D. Johnston ( jamesjoh@uoregon.edu )
In Oregon, researchers constructed historical fire records for 36 stands of Douglas-fir forests on the slopes of the Cascade Mountains to examine how fire patterns have changed over time. To piece together this history, they examined old tree stumps for fire scars, reading the tree rings to see when past fires burned and when new trees first took root. What emerged was a picture of remarkable variability: some sites showed evidence of massive, stand‑replacing fires; others experienced repeated low‑ or moderate‑severity burns; and many fell somewhere in between. The stands were found to have mostly established following exceptionally large fires 200–750 years old. Afterward, lower severity fires burned widely and frequently across the landscape, creating forests of mixed tree ages. Although fires were more likely during dry periods and in areas with earlier snowmelt, periods of widespread burning occurred repeatedly over the past seven centuries, suggesting that Douglas-fir forests burned often and did not experience long fire-free stretches, as was once thought. In recent years, however, management strategies focused on suppressing or minimizing wildfires have greatly altered the fire conditions under which these forests have grown. Because the historical fire regime was far more varied than we previously thought, the authors argue that management should better account for the diverse roles fire has long played in shaping the Pacific Northwest’s forests.
Read the article: Diverse historical fire disturbance and successional dynamics in Douglas-fir forests of the western Oregon Cascades, USA
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