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This study was conducted in Barangay Badiangan, Ajuy, Iloilo City, Philippines (11°10’N, 122°58’E) to determine the effects of rainfall intensity and other rainfall-derived parameters on the directional components of splash erosion in hillslopes. There are five experimental set-ups with slope angles ranging from 0% to 48% were tested under natural rainfall conditions using a modified splash collector. The data collected shows that kinetic energy, slope, and rainfall intensity have shown significant effects on splash erosion. The models obtained using regression analysis are =0.0093( 0.80) and =0.060( 0.107)( 0.700)( 200.700) . The model equation performance has been validated using the Standard Error of Estimates with values of 12 and 9.4 for splash detachment and splash transport, respectively. The constants used for kinetic energy in detachment and slope in transport align with the research by Quansah (1981) for sandy soil, which is similar (the characteristics) to the soil at our research site. Additionally, rainfall intensity, especially with a 20-min duration, generated the best model as it yielded the lowest SEE value for all cases.

Increased wildfire activity in the western United States has exposed regional gaps in our understanding of postfire debris‐flow generation. To address this problem, we characterized flows in an unstudied area to test the rainfall intensity‐duration control of the hazard. Our rainfall measurements and field observations from the northern Sierra Nevada (California, USA) show that debris flows resulted from a short burst rainfall during a low‐accumulation storm. In contrast, a much higher accumulation storm (∼10 times more rainfall) with lower short‐duration rainfall rates only produced low‐hazard flooding. We conclude that total storm rainfall is not an ideal metric for identifying the rainfall conditions that initiate runoff‐generated debris flows in the first year after wildfire. Rather, a focus on short‐duration (<1 hr), high‐intensity rainfall that can occur during localized thunderstorms, or bands of intense rainfall during prolonged rainstorms, is more beneficial for the purposes of hazard assessment and warning. Plain Language Summary The rainfall conditions that trigger fast‐moving slurries of water and debris (or “debris flows”) after wildfire have been studied extensively in southern California. However, the transferability of these concepts to areas further north along the western margin of the United States in regions that are being affected by increased fire activity is unclear. We present rainfall measurements from contrasting storm types that affected an area burned by the 2021 Dixie Fire in northern California and describe the resultant postfire flows, which ranged from nuisance water‐rich flows to large and dangerous debris flows. Short bursts of rainfall, as opposed to prolonged (multiday) periods of rainfall, initiated the most hazardous flows. We conclude that rainfall intensity measured over short durations, not storm rainfall total, is the most useful measure of rainfall for identifying runoff‐induced debris‐flow hazard potential in the first year after fire. Key Points Postfire debris flows described in region where they were previously undocumented Flow type and sediment yield controlled by differences in short‐duration rainfall rates Debris‐flow initiation not sensitive to storm rainfall totals in first year after fire

Nearly all microbial communities are dynamic in time. Understanding how temporal dynamics in microbial community structure affect soil biogeochemistry and fertility are key to being able to predict the responses of the soil microbiome to environmental perturbations. Here, we explain the effects of soil spatial structure and relic DNA on the determination of microbial community fluctuations over time. We found that intensive spatial sampling was required to identify temporal effects in microbial communities because of the high degree of spatial heterogeneity in soil and that DNA from nonliving sources masks important temporal patterns. We identified groups of microbes with shared temporal responses and show that these patterns were predictable from changes in soil characteristics. These results provide insight into the environmental preferences and temporal relationships between individual microbial taxa and highlight the importance of considering relic DNA when trying to detect temporal dynamics in belowground communities. Few studies have comprehensively investigated the temporal variability in soil microbial communities despite widespread recognition that the belowground environment is dynamic. In part, this stems from the challenges associated with the high degree of spatial heterogeneity in soil microbial communities and because the presence of relic DNA (DNA from dead cells or secreted extracellular DNA) may dampen temporal signals. Here, we disentangle the relationships among spatial, temporal, and relic DNA effects on prokaryotic and fungal communities in soils collected from contrasting hillslopes in Colorado, USA. We intensively sampled plots on each hillslope over 6 months to discriminate between temporal variability, intraplot spatial heterogeneity, and relic DNA effects on the soil prokaryotic and fungal communities. We show that the intraplot spatial variability in microbial community composition was strong and independent of relic DNA effects and that these spatial patterns persisted throughout the study. When controlling for intraplot spatial variability, we identified significant temporal variability in both plots over the 6-month study. These microbial communities were more dissimilar over time after relic DNA was removed, suggesting that relic DNA hinders the detection of important temporal dynamics in belowground microbial communities. We identified microbial taxa that exhibited shared temporal responses and show that these responses were often predictable from temporal changes in soil conditions. Our findings highlight approaches that can be used to better characterize temporal shifts in soil microbial communities, information that is critical for predicting the environmental preferences of individual soil microbial taxa and identifying linkages between soil microbial community composition and belowground processes. IMPORTANCE Nearly all microbial communities are dynamic in time. Understanding how temporal dynamics in microbial community structure affect soil biogeochemistry and fertility are key to being able to predict the responses of the soil microbiome to environmental perturbations. Here, we explain the effects of soil spatial structure and relic DNA on the determination of microbial community fluctuations over time. We found that intensive spatial sampling was required to identify temporal effects in microbial communities because of the high degree of spatial heterogeneity in soil and that DNA from nonliving sources masks important temporal patterns. We identified groups of microbes with shared temporal responses and show that these patterns were predictable from changes in soil characteristics. These results provide insight into the environmental preferences and temporal relationships between individual microbial taxa and highlight the importance of considering relic DNA when trying to detect temporal dynamics in belowground communities.

【Background and Objective】 Water erosion is a common form of soil degradation, affecting 1.071 4 million km2 of soil in China, accounting for 40.77% of national soil erosion. While the soil surface in most regions in Northeastern China is relatively flat, the black soils are susceptible to water erosion due to their unique environment and unsustainable agricultural practices, threatening food production and ecological security. Tremendous efforts have been made in improving the black soil and water conservation to ameliorate water erosion. This paper reviews the progress made over the past decades. 【Method】 The review was based on literature and data related to water erosion in sloped black soils and their mitigation technologies, with the focus on the influence of rainfall, topography, vegetation, soil condition and human activities. 【Result】 The area of soils affected by water erosion was approximately 133 200 km2, accounting for 63.76% of total eroded black soils in the region. Hillslope and gully erosion are the predominant erosion patterns, forming a hillslope-gully system that is a major source of sediment. Key erosion-control technologies included ridge tillage, straw return, ridge planting, hedgerows, terracing, minimal tillage with residue mulching, no-tillage, and gully control. Critical issues in implementing these technologies include a detailed understanding of their underlying mechanisms, effectiveness, optimal configurations, and selection for different regions. Future research should focus on improving understanding of the mechanisms of these technologies, establishing a comprehensive erosion-control system, and developing strategies for regulating runoff and soil consolidation. 【Conclusion】 Water erosion is a great challenge in sloped black soil farmland in Northeastern China, influenced by both natural factors and human activities. Significant efforts have been made in alleviating water erosion both theoretically and practically. This review serves as a foundation for advancing research and developing strategies to mitigate water erosion in sloped black soils and similar environments.

The processes of ice incorporation into rock glaciers have been difficult to quantify in both permafrost and non‐permafrost conditions. Here, we develop a numerical model that regardless of the presence of permafrost, reveals how debris eroded from hillslopes and deposited on snow can add ice mass to rock glaciers in pulses. Importantly, we honor the reality in all mountain systems that snow amount, snow avalanches, melt, and mass wasting vary stochastically. Our probabilistic model reproduces the internal stratigraphy (of firn and debris) from high on Timpanogos Rock Glacier, Wasatch Mountains, Utah, USA, which intermittently has an accumulation zone. Even in the modern arid, warming western United States the combined variability of familiar mountain processes allows rock glaciers to add ice. We provide a numerical framework for simulating the continuum between glaciers, debris‐covered glaciers, and rock glaciers in response to climate change.

Abstract PurposeRoot reinforcement is a key parameter in slope stability analysis, but is difficult to be effectively included at the hillslope-scale due to the complexity of root systems. As a result, hillslope-scale analysis of root reinforcement still requires high levels of field validation to account for variability in root properties as a function of topography, ecology, and soil properties. This study investigated root distributions and estimated root reinforcement at an unprecedent scale of field and laboratory measurement, using this to understand differences among species (Carpinus betulus and Fagus orientalis), diameter at breast height (DBH), slope position, altitude, vertical and horizontal distances from trees in Hyrcanian temperate forests, Iran.MethodWe excavated 1080 profile trenches 0.5 m wide, 1.0 m length, and 1.0 m deep upslope and downslope from trunks of C. betulus and F. orientalis with a range of DBH (7.5–82.5 cm) at three different altitudes (400, 950, and 1300 m a.s.l.). We assessed the effects of different forest coverage on slope stability via a 3-D limit equilibrium-based slope stability model where parameter uncertainties are explicitly accounted for using Monte Carlo Simulation.ResultsThe Root Area Ratio (RAR) of C. betulus is always higher than F. orientalis. RAR of F. orientalis is higher in upslope, whereas RAR of C. betulus is similar in both positions. Higher RAR contributed to higher root reinforcements for C. betulus when comparted with F. orientalis. Additionally, after accounting for DBH influences, altitude significantly affects the root reinforcement of C. betulus. The results of slope stability analysis showed that the most stabilizing species is C. betulus in a mature growth condition, maintaining an instability probability of ~ 18.3%.ConclusionC. betulus is preferable to F. orientalis for increasing slope stability. Forest managers should consider this outcome when developing strategies for silvicultural treatment and reforestation projects in mountainous areas of temperate regions.

Strike‐slip faults act as landscape change agents, offsetting rivers, driving river capture, and generating hillslope responses. In this study, inspired by the hyperarid Atacama Fault System in Chile, we use numerical models to investigate how landscapes that experience oscillatory dry and humid periods respond to strike‐slip faulting at variable slip rates. Our results show that riverbed aggradation from hillslope sediment flux during dry periods delays stream capture, increases deflection angles of fault‐crossing channels, and produces highly perturbed longitudinal river profiles. In some cases, these phenomena, as well as the thickness of aggraded sediment, are slip‐rate dependent. Lags in capture timing and/or fully missed captures that occur in landscapes with climatic oscillation have a profound impact on the long‐term evolution of strike‐slip landscapes. Our work also highlights the importance of hillslope contributions to landscape modification in arid and semi‐arid settings with ephemeral rivers.

Thawing of ice-rich permafrost soils in sloped terrain can lead to activation of retrogressive thaw slumps (RTSs) which make organic matter available for decomposition that has been frozen for centuries to millennia. Recent studies show that the area affected by RTSs increased in the last two decades across the pan-Arctic. Combining a model of soil carbon dynamics with remotely sensed spatial details of thaw slump area and a soil carbon database, we show that RTSs in Siberia turned a previous quasi-neutral ecosystem into a strong source of carbon dioxide of 367 ± 213 gC m-1 a-1. On a global scale, recent CO 2 emissions from Siberian thaw slumps of 0.42 ± 0.22 Tg carbon per year are negligible so far. However, depending on the future evolution of permafrost thaw and hence thaw slump-affected area, such hillslope processes can transition permafrost landscapes to become a major source of additional CO 2 release into the atmosphere.

The length of hillslope flowpaths plays a crucial role in various hydrological, geomorphological and ecological processes. However, hillslope lengths change as the flowing network expands or contracts in response to precipitation. Currently, there is limited understanding of how channel network dynamics influence the distribution of hillslope flowpaths, with existing studies primarily focusing on the numerical analysis of specific case studies. In this work, we propose an analytical framework to characterize the general principles underlying variations in the hillslope length distribution as a function of the total length of the drainage network, L$L$ . Our model provides a closed‐form solution for the probability density function of the distance‐to‐channel conditioned on the total flowing network length, ω(ℓ,L)$\\omega (\\ell ,L)$ . As a benchmark, the model has been applied to 15 headwater catchments with a non‐perennial river network, achieving reasonably good performances. The model captures the change in shape of the hillslope length distribution as the network expands, in particular the increased probability associated with shorter flowpaths. Empirical data and model results suggest the existence of some universal features in the way the hillslope length pdf responds to variations in the flowing network: longer paths are systematically more affected than shorter ones, and the overall fraction of impacted pathways decreases as the channel network lengthens. Besides the theoretical insights, our method offers a simple analytical means to determine the shape of the hillslope length distribution for varying drainage densities, even when the numerical evaluation of ω(ℓ,L)$\\omega (\\ell ,L)$is challenging. Key Points Development of a mathematical model to describe the change of shape of the hillslope length distribution caused by channel network dynamics Comparison of the new model with empirically computed distributions from DTMs of 15 catchments Short hillslope paths are usually less impacted by network dynamics than the long paths