Climate and forest biodiversity
H. J. Andrews Experimental Forest, Oregon.
Few studies have examined how environmental conditions affect trait diversity among organisms within an ecosystem on a global scale. To uncover how climate affects the functional diversity of forests, Daniel Wieczynski et al. (pp. 587–592) analyzed data from 421 tree communities around the world, 66 of which were sampled in situ. The dataset included 55,983 individual trees of 2,701 species. The authors examined a variety of functional traits that affect both individual plant growth and overall forest productivity, such as leaf area, seed mass, plant height, amount of leaf-produced carbon, nitrogen, and phosphorus, and ratio of nitrogen to phosphorus. The authors also measured various climatic factors for each community, including precipitation, solar radiation, temperature, vapor pressure, and wind speed. Temperature variability and vapor pressure had the greatest influence on trait diversity within and across communities. High latitudes and elevations reduced community functional diversity across all traits, except seed mass, which was largely affected by precipitation and wind speed. According to the authors, climate change may affect not only functional traits of communities but also species distribution across the globe. — M.S.
Exploring plasma DNA fragmentation
Short fragments of DNA circulating in plasma can be analyzed for cancer diagnosis and prenatal testing, but the mechanisms by which plasma DNA is fragmented are unclear. Lee Serpas, Rebecca Chan, et al. (pp. 641–649) found that loss of the secreted nuclease DNase1-like 3 (DNASE1L3) resulted in the aberrant fragmentation of plasma DNA. Loss of Dnase1L3 was associated with an increase in plasma DNA molecules above 250 bp and below 120 bp in size, and the latter were positively correlated with anti-DNA antibody levels. The results suggest that the increase in relatively long DNA fragments may be a primary effect of DNASE1L3 deficiency, whereas the increase in short DNA fragments may be the result of the anti-DNA response. DNASE1L3 loss also caused a decrease in frequencies of the most common plasma DNA end sequence motifs. In Dnase1l3 knockout mice pregnant with fetuses heterozygous for Dnase1l3, the authors found partial restoration of normal frequencies of plasma DNA end motifs, suggesting that DNASE1L3 from fetuses had a systemic effect on maternal plasma DNA in addition to a local effect on fetal DNA. According to the authors, DNASE1L3 plays a role in the fragmentation of circulating plasma DNA, and exploring plasma DNA fragmentation could help improve molecular diagnostics and reveal how DNASE1L3 prevents autoimmunity. — S.R.
Climate change and electricity consumption in China
Air conditioning and heating are major drivers of growth in residential electricity consumption in China. Image courtesy of Pixabay/ElasticComputeFarm.
Climate change is expected to have a substantial impact on electricity consumption. Most empirical estimates of links between temperature and electricity consumption focus on developed countries, with comparatively less research from China. Yating Li et al. (pp. 472–477) estimated a temperature–electricity relationship based on daily electricity use data from more than 800,000 residential customers in the Pudong district of Shanghai between 2014 and 2016. For temperatures above 25 °C, daily electricity consumption increased by 14.5% for every 1 °C increase in daily temperature. Electricity consumption was nearly independent of temperature between 13 °C and 25 °C, and increased moderately with decreasing temperature below 13 °C. By combining this empirical relationship with results from climate model simulations, the authors estimated that by the end of the 21st century, annual mean residential electricity consumption would increase by approximately 9.2% for each 1 °C increase in global mean surface temperature (GMST) relative to the late 20th century. During the same period, annual peak consumption would increase by 36.1% for each 1 °C increase in GMST. According to the authors, the results could be applied to other urban areas throughout the Yangtze River Delta, a relatively wealthy and populous region of China, and might contribute to planning climate change mitigation efforts. — B.D.