Habitat covariates do not artificially cause a negative correlation between native and non-native species richness.

When analyzing biotic resistance/diversity-invasibility, including predictors of species richness may result in a false negative correlation between native and non-native richness. However, reanalysis of vegetation surveys shows that the negative effect of native richness is statistically significant whether or not predictors of species richness are included.

Biotic resistance to invasion is ubiquitous across ecosystems of the United States.

The biotic resistance hypothesis predicts that diverse native communities are more resistant to invasion. However, past studies vary in their support for this hypothesis due to an apparent contradiction between experimental studies, which support biotic resistance, and observational studies, which find that native and non-native species richness are positively related at broad scales (small-scale studies are more variable). Here, we present a novel analysis of the biotic resistance hypothesis using 24 456 observations of plant richness spanning four community types and seven ecoregions of the United States.

Invasive grasses increase fire occurrence and frequency across US ecoregions.

Fire-prone invasive grasses create novel ecosystem threats by increasing fine-fuel loads and continuity, which can alter fire regimes. While the existence of an invasive grass-fire cycle is well known, evidence of altered fire regimes is typically based on local-scale studies or expert knowledge. Here, we quantify the effects of 12 nonnative, invasive grasses on fire occurrence, size, and frequency across 29 US ecoregions encompassing more than one third of the conterminous United States.

Warming seas increase cold-stunning events for Kemp's ridley sea turtles in the northwest Atlantic.

Since the 1970s, the magnitude of turtle cold-stun strandings have increased dramatically within the northwestern Atlantic. Here, we examine oceanic, atmospheric, and biological factors that may affect the increasing trend of cold-stunned Kemp's ridleys in Cape Cod Bay, Massachusetts, United States of America. Using machine learning and Bayesian inference modeling techniques, we demonstrate higher cold-stunning years occur when the Gulf of Maine has warmer sea surface temperatures in late October through early November.

Quantifying the human influence on fire ignition across the western USA.

Humans have a profound effect on fire regimes by increasing the frequency of ignitions. Although ignition is an integral component of understanding and predicting fire, to date fire models have not been able to isolate the ignition location, leading to inconsistent use of anthropogenic ignition proxies. Here, we identified fire ignitions from the Moderate Resolution Imaging Spectrometer (MODIS) Burned Area Product (2000-2012) to create the first remotely sensed, consistently derived, and regionally comprehensive fire ignition data set for the western United States.

Factors affecting branch failures in open-grown trees during a snowstorm in Massachusetts, USA.

In October 2011, a snowstorm in the northeastern USA caused many branch failures of many tree species commonly planted in urbanized settings. Immediately following the storm, we assessed 1,764 trees for possible snow-induced damage and factors affecting it on the campus of the University of Massachusetts in Amherst, MA, USA. Nearly all failures were of branches, most of which were not defective.

Rapid assessment of soil erosion in the Rio Lempa Basin, Central America, using the universal soil loss equation and geographic information systems.

Soil erosion is a severe problem for many developing regions that lack adequate infrastructure to combat the problem. The authors established a first-order method for prioritizing areas to be examined and remediated using preexisting data and expert knowledge where data are lacking. The Universal Soil Loss Equation was applied to the Rio Lempa Basin in Central America using geographic information systems and remote sensing technologies, and the estimated erosion rates were compared with sediment delivery ratios.

Axonal self-destruction and neurodegeneration.

Neurons seem to have at least two self-destruct programs. Like other cell types, they have an intracellular death program for undergoing apoptosis when they are injured, infected, or not needed. In addition, they apparently have a second, molecularly distinct self-destruct program in their axon.