Below-canopy downwelling shortwave radiation (SWR) influences snow ablation, soil microclimate, and carbon uptake, yet remains difficult to map in heterogeneous forests. To address this, we measured below-canopy SWR using a 122-m cable-borne mobile tram equipped with an upward-facing pyranometer along a transect spanning a subalpine forest-to-fen ecotone. Subsequently, airborne lidar-derived forest structure was used in a Lidar-to-Radiation canopy ray tracing model to simulate spatial patterns of SWR at 30-min timesteps across the full growing season (21 Mar. - 21 Sep. 2023). Simulated SWR demonstrated strong agreement with field measurements (Spearman ρ = 0.95). At 1-m horizontal resolution, the model captured tree- and gap-scale variability and growing-season contrasts. When applied to two neighboring 1 ha forest plots, simulated SWR had a monotonic, log-linear relation with sky-view factor (SVF) (R2 = 0.96 and 0.78). SVF adequately explained the mean tendency but not the fine-scale or temporal variation of SWR. Within a single SVF class (±5% SVF interval), growing-season SWR spanned wide ranges (e.g., 46-166 W m-2 at 10% SVF and 311-398 W m-2 at 50% SVF), suggesting additional geometric controls such as relative crown position, height, and shape that were not captured by SVF. Thus, ecohydrological extremes—early snow disappearance, soil moisture deficits, or persistent shade—can coexist within a narrow SVF range. Results demonstrate the ability of a three-dimensional ray tracing model to capture sunflecks, canopy edge shadows, and terrain masking in a subalpine forest. Model errors likely reflect sensitivity to woody element representation, meter-scale uncertainty in lidar geolocation and sensor positioning, and model parameters. Coupled observation and model systems provide a transferable method to scale results from meteorological stations to transects and landscapes. Integrating such detailed measurements with process-based modeling is essential for understanding how canopy structure shapes energy availability, soil moisture and plant water availability, and land-atmosphere interactions.
Animals shape Earth surface processes and landforms by displacing Earth surface materials and by making them more or less susceptible to geophysical processes. Despite increased recognition of the global significance of animal landscape "signatures", analysis of their magnitude and generality has not been possible until now. We present a meta-analysis of zoogeomorphic effect sizes using a comprehensive data set derived from a systematic review of published research. Our analysis provides unequivocal statistical evidence that wild animal agents substantially change geomorphic properties, on average by 136% in freshwaters and 66% in terrestrial ecosystems. Irrespective of ecosystem type, the presence of an animal agent increased substrate porosity and reduced the absolute or relative amount of fine material, properties that influence water and sediment fluxes and potentially landscape resilience. Livestock effect size data were scarce (two taxa), so analysis was focused on 61 wild animal species. While our analysis is the most extensive to-date, spanning nine taxonomic classes across freshwater and terrestrial ecosystem types, hundreds more animal geomorphic agents are not represented due to a lack of effect size data. In contrast to prevailing hypotheses, we found little evidence of reduced effect sizes in settings with higher potential geophysical energy; instead, relationships with energy context were nuanced and dependent on geomorphic signature. Our findings show that wild animal geomorphic effects are not of low magnitude, nor are they limited to a handful of species, ecosystem types, or energy contexts. These findings challenge orthodox assumptions that geophysical drivers dominate Earth surface processes, and landform and landscape evolution.
The bacterial genus Endozoicomonas is prevalent and abundant in the microbiome of many corals, but the combination of environmental and host factors shaping its distribution remains uncertain. In this study, we used 16S rRNA gene sequencing to examine the distribution of Endozoicomonas across hard (Porites astreoides, Montastraea cavernosa, Agaricia spp.) and soft coral (Muricea spp., Gorgoniidae, Cladiellidae, Malacalcyonacea) microbiomes across a depth gradient from shallow (4.5 m) to upper mesophotic zones (36.6 m) at four sites around the Little Cayman Island, including two marine protected areas. Endozoicomonas was abundant across all coral microbiomes, with soft corals exhibiting near-total dominance (relative abundance range 0.1–99
Shear zone systems exposed in the crystalline rocks of Colorado record Proterozoic deformation episodes documenting strain partitioning, reactivation and the progressive tectonic evolution of SW Laurentia. These structures, and their equivalents throughout the southwestern USA, provide insight into the structural evolution of the North American craton, and inform tectonic models for an active, but challenging to decipher period in Earth's history. NE-SW-trending mylonitic bands record regional fold formation and establishment of sub-vertical D-1/D-2 shear zones occurred during the successive c. 1720-1600 Ma Yavapai and Mazatzal orogenies, and D-3/D-4 reactivation of these structures during the c. 1450-1300 Ma Picuris Orogeny. The shallowly dipping Slide Lake Shear Zone (SLSZ), in Colorado's Sawatch Range, is adjacent to the steeply dipping Homestake Shear Zone (HSZ), allowing for comparison between high- and low-angle faulting in mid-crustal positions associated with the long-lived Laurentian orogenic margin throughout the Proterozoic. Both structures record similar deformational conditions and bulk NW-SE-verging kinematics. Newly obtained in situ electron microprobe monazite U-Th-Pb geochronology and trace element geochemistry constrain the timing and nature of SLSZ activity, allowing direct comparison with established HSZ activity. Core domains in a steeply dipping segment of the SLSZ record mineral growth during the Yavapai Orogeny (D-1) at c. 1700 +/- 14 Ma, and support continued SLSZ activation during the Mazatzal Orogeny (D-2). Low-angle segments preserve deformation associated with the Mesoproterozoic Picuris Orogeny (D-3/D-4) at c. 1450-1300 Ma. The age progression of the SLSZ parallels the structural evolution of the HSZ, indicating that sub-horizontal, transtensional, D-3/D-4 slip on the SLSZ was coeval with sub-vertical, transpressional, D-3/D-4 slip on the HSZ. Cumulatively, the existing structural and newly established temporal history of the HSZ-SLSZ system is interpreted to indicate that oblique extensional and compressional strain were competing in the middle crust within the Laurentian interior during the Picuris Orogeny, lending credence to models of plateau-style crustal thickening and collapse during this event.
ABSTRACT Gallium nitride (GaN) is near ubiquitous in modern day technologies, forming the backbone of solid‐state lighting and high‐power electronics. Engineering the physical properties of GaN has been investigated to some degree by the incorporation or doping of most of the elements of the periodic table, but the actinides remain unexplored. Molecular beam epitaxy is used to demonstrate uranium doping of GaN single crystals. High structural quality of the host matrix is maintained despite partial elemental segregation of the uranium dopant into 1D structures at the levels presented here. Electronic transport measurements reveal relatively high conductivity, which persists down to cryogenic temperature and is characterized by the formation of narrow gaps in the electronic band structures very close to the Fermi level. Photoluminescence measurements reveal that the U‐doped GaN exhibits optical behavior similar to that of the GaN substrate. The addition of actinide materials to a non‐centrosymmetric, optically active, radiation‐hard, and electronically tunable host matrix opens a world of possibilities for investigating and leveraging elements with high electron correlations in the pursuit of novel devices.
