Reading tea leaves worldwide: decoupled drivers of initial litter decomposition mass-loss rate and stabilisation

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models

GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object

We report the observation of a compact binary coalescence involving a 22.2–24.3 Me black hole and a compact object with a mass of 2.50–2.67 Me (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of - + 241 45 41 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, - + 0.112 0.009 0.008, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to �0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries

Estimating brown hyaena occupancyusing baited camera traps

Conservation and management of brown hyaenas (Hyaena brunnea) is hampered by a lack ofinformation on abundance and distribution, which is difficult and labour-intensive to obtain.However, occupancy surveys offer a potentially efficient and robust means of assessingbrown hyaena populations. We evaluate the efficacy of camera trapping for estimatingbrown hyaena occupancy, and the effect of environmental variables and lures on detectionprobability. We estimated population density in Pilanesberg National Park, South Africa, at2.8/100 km2, occupancy at 1.0 and model-averaged detection probability at 0.1. Using a fishlure increased detection probability to 0.2 and significantly increased encounter rates. Wealso found that brown hyaenas are more likely to be detected in areas of scrub or woodlandrather than grassland. Our results suggest that 13 camera sites would be needed to achievean occupancy estimate with S.E. of 0.05, and a minimum of 16–34 sampling occasions (withand without the fish lure) should be used in comparable study areas. We conclude thatcamera trapping is a viable method of estimating brown hyaena occupancy at local andlandscape scales and capture–recapture analysis is also possible at a local scale