Forest soil is crucial in climate change mitigation, food security, and biogeochemical nutrient cycling. Mixed Sal forests enhance soil organic matter, improve nutrient availability, and regulate pH dynamics. However, anthropogenic disturbances, including deforestation and land-use changes, significantly alter forest cover, leading to shifts in soil physicochemical and microbial properties. These impacts necessitate rigorous monitoring and comprehensive assessment. Therefore, we investigated the effects of contrasting conditions- closed (no human activities) and open (human interferences) mixed Sal Forest on the vertical and seasonal dynamics of microbial biomass carbon (SMBC). Results revealed that the closed mixed Sal Forest had significantly higher SMBC than the open mixed Sal Forest across the soil profile (D1-D5) with a strong seasonal effect. Closed mixed Sal Forest had 60% higher SMBC in D1 than open mixed Sal Forest while it reduced with depth and 17.1 to 56.7% higher SMBC in the subsurface to bottom-most soil profile (D2-D5). Moreover, SMBC was higher in the monsoon period in both forests. The SMBC reduced by 24.2 to 45.1% in the post-monsoon period while reduction was more intense in the pre-monsoon period (48.1 to 68.2%) compared to the monsoon period under closed mixed Sal Forest. Similarly, the decline was more intense in the open mixed Sal Forest, where SMBC declined 12.1 to 54% in the post-monsoon period and 56.1 to 76.2% in the pre-monsoon period compared to the monsoon period. The study indicates that human interference in mixed Sal forests leads to loss of forest cover, negatively affecting microbiological properties and reducing soil fertility, which weakens the forest's resilience to climate change. Additionally, SMBC exhibits seasonal variations, reflecting responses to environmental conditions. These results underline the need to reduce human disturbances and enhance forest conservation strategies to ensure soil sustainability and ecosystem stability.

Aerosol single-scattering albedo (SSA) is the most critical factor for the accurately calculating of aerosol radiative effects, however, the observation of vertical profiles of SSA is difficult to realize. Current assessments of aerosol radiative effects remain uncertain because of the lack of long-term, high-resolution vertical profiles of SSA observations. High-resolution SSA vertical profiles were observed in a semi-arid region of Northwest China during winter using a tethered balloon. The observed SSA vertical profiles were used to calculate the aerosol direct radiative forcing and radiative heating rates. Significant differences in the calculated radiative forcing were found (e.g., a 48.3% relative difference for the heating effect in the atmosphere at 14:00) between the observed SSA profiles and the constant assumption with SSA = 0.90. Diurnal variations in the vertical distribution of SSA decisively influenced direct radiative forcing of aerosols. Furthermore, high-resolution vertical profiles of absorbing aerosols and meteorological parameters provide robust observational evidence of the heating effect of an elevated absorbing aerosol layer. This study provides a more accurate calculation of aerosol radiative forcing using observed aerosol SSA profiles. The scarcity of single-scattering albedo (SSA) observations is the most critical factor limiting the accurate calculations of aerosol radiative effects. A tethered balloon platform was used to obtain long-term, high-resolution observations of the SSA and estimate aerosols' radiative effects. The relative differences in the heating rate and direct radiative forcing calculations using the observed SSA and a constant assumed SSA (i.e., ignoring the vertical distribution of absorbing aerosols) were quantified. The effects of diurnal variations in the vertical distribution of SSA on aerosol direct radiative forcing are summarized. This study has important scientific implications for assessing the radiative effects of aerosols in semi-arid regions, that are highly sensitive to climate change. Tethered balloon observations acquired high-resolution vertical aerosol single-scattering albedo (SSA) profiles The assumed SSA profiles caused a 48.3% relative error in radiative forcing in the atmosphere compared to the observed profiles at 14:00 A robust observational evidence of atmospheric heating by absorbing aerosols above the boundary layer was provided

Although herbivores are well known to incur positive density-dependent damage and mortality, thereby likely shaping plant community assembly, the response of belowground root feeders to changes in plant density has seldom been addressed. Locally rare plant species (with lower plant biomass per area) are often smaller with shallower roots than common species (with higher plant biomass per area) in competition-intensive grasslands. Likewise, root feeders are often distributed in the upper soil layers. We hypothesized, therefore, that root feeders would incur negative density (biomass)-dependent damage across plant species. To test this hypothesis, we investigated the diversity and abundance of plant and root feeder species in an alpine meadow and determined the diet of the root feeders using metabarcoding. Across all species, root feeder load decreased with increasing aboveground plant biomass, root biomass, and total plant biomass per area, indicating a negative density dependence of damage across plant species. Aboveground plant biomass per area increased with increasing individual plant biomass and root depth per area across species, suggesting that rare plant species were smaller in size and had shallower root systems compared to common plant species. Both root biomass per area and root feeder biomass per area decreased with soil depth, but the root feeder biomass decreased disproportionately faster compared to root biomass with increasing root depth. Root feeder load decreased with increasing root depth but was not correlated with the feeding preference of root feeder species. Moreover, the prediction derived from a random process incorporating vertical distributions of root biomass and root feeder biomass significantly accounted for interspecific variation in root feeder load. In conclusion, the data indicate that root feeders incur negative density-dependent damage across plant species. On this basis, we suggest that manipulative experiments should be conducted to determine the effect of the negative density-dependent damage on plant community structure and that different types of plant-animal interactions should be concurrently examined to fully understand the effect of plant density on overall herbivore damage across plant species.

Atmospheric aerosols have important impacts on global radiative forcing, air pollution, and human health. This study investigated the optical and physical properties of aerosol layers over Australia from 2007 to 2019 using the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) Level 2 aerosol products. Australia was divided into three sub-regions (western highlands, central plains, and eastern ranges). Interannual and seasonal optical property variations in aerosol layers in the three sub-regions were analyzed and compared. Results showed that annual mean values of AOD(L) (lowest aerosol layer AOD) and AOD(T) (total AOD of all aerosol layers) were always higher in the eastern ranges region than the other two regions from 2007 to 2019. The reason could be that Australian population was predominantly located in the eastern ranges region, where more human activities could bring significant aerosol loadings. B-L (base height of the lowest aerosol layer), H-L (top height of the lowest aerosol layer), and H-H (top height of the highest aerosol layer) all showed trends of western highlands > eastern mountains > central plains, indicating that the higher the elevation, the higher the B-L, H-L, and H-H. T-L (thickness of the lowest aerosol layer) was higher during the day than at night, which might account for increased diurnal atmospheric convection and nocturnal aerosol deposition. DRL (depolarization ratio of the lowest aerosol layer) was higher in the western highlands and central plains than the eastern mountains, probably because these two regions have large deserts with more irregularly shaped dust aerosols. CRL (color ratio of the lowest aerosol layer) had slightly higher values in the eastern ranges than the other two regions, probably due to the wet climate of the eastern ranges, where aerosols were more hygroscopic and had larger particle sizes. This study can provide technical support for the control and management of regional air pollutants.

Aerosol direct radiative forcing is strongly dependent on aerosol distributions and aerosol types. A detailed understanding of such information is still missing at the Alpine region, which currently undergoes amplified climate warming. Our goal was to study the vertical variability of aerosol types within and above the Vipava valley (45.87 degrees N, 13.90 degrees E, 125 m a.s.1.) to reveal the vertical impact of each particular aerosol type on this region, a representative complex terrain in the Alpine region which often suffers from air pollution in the wintertime. This investigation was performed using the entire dataset of a dual-wavelength polarization Raman lidar system, which covers 33 nights from September to December 2017. The lidar provides measurements from midnight to early morning (typically from 00:00 to 06:00 CET) to provide aerosol-type dependent properties, which include particle linear depolarization ratio, lidar ratio at 355 nm and the aerosol backscatter Angstrom exponent between 355 nm and 1064 nm. These aerosol properties were compared with similar studies, and the aerosol types were identified by the measured aerosol optical properties. Primary anthropogenic aerosols within the valley are mainly emitted from two sources: individual domestic heating systems, which mostly use biomass fuel, and traffic emissions. Natural aerosols, such as mineral dust and sea salt, are mostly transported over large distances. A mixture of two or more aerosol types was generally found. The aerosol characterization and statistical properties of vertical aerosol distributions were performed up to 3 km.

Soil microorganisms are crucial contributors to the function of permafrost ecosystems, as well as the regulation of biogeochemical cycles. However, little is known about the distribution patterns and drivers of high-latitude permafrost microbial communities subject to climate change and human activities. In this study, the vertical distribution patterns of soil bacterial communities in the Greater Khingan Mountain permafrost region were systematically analyzed via Illumina Miseq high-throughput sequencing. Bacterial diversity in the active layer was significantly higher than in the permafrost layer. Principal coordinate analysis (PCoA) indicated that the bacterial community structure in the active layer and the permafrost layer was completely separated. Permutational multivariate analysis of variance (PERMANOVA) detected statistically significant differentiation across the different depths. The relative abundance of the dominant phyla Chloroflexi (17.92%-52.79%) and Actinobacteria (6.34%-34.52%) was significantly higher in the permafrost layer than in the active layer, whereas that of Acidobacteria (4.98%-38.82%) exhibited the opposite trend, and the abundance of Proteobacteria (2.49%-22.51%) generally decreased with depth. More importantly, the abundance of bacteria linked to human infectious diseases was significantly higher in the permafrost layer according to Tax4Fun prediction analysis. Redundancy analysis (RDA) showed that ammonium nitrogen (NH4+-N), total organic carbon (TOC), and total phosphorus (TP) were major factors affecting the bacterial community composition. Collectively, our findings provide insights into the soil bacterial vertical distribution patterns and major environmental drivers in high-latitude permafrost regions, which is key to grasping the response of cold region ecosystem processes to global climate changes.

Aerosol microphysical properties, scattering and absorption characteristics, and in particular, the vertical distributions of these parameters over the eastern Loess Plateau, were analyzed based on aircraft measurements made in 2020 during a summertime aircraft campaign in Shanxi, China. Data from six flights were analyzed. Statistical characteristics and vertical distributions of aerosol concentration, particle size, optical properties, including aerosol scattering coefficient (Sigma sp), backscattering ratio (beta sc), Angstro spacing diaeresis m exponent (alpha), single-scattering albedo (SSA), partially-integrated aerosol optical depth (PAOD), and black carbon concentration (BCc), were obtained and discussed. Mean values of aerosol particle number concentration (Na), particle volume concentration (Va), mass concentration (Ma), surface concentration (Sa), and particle effective diameter (EDa) were 854.92 cm-3, 13.37 mu m3 cm- 3, 20.06 mu g/m3, 170.08 mu m3 cm- 3, and 0.47 mu m, respectively. Mean values of BCc, Sigma sp (450, 525, 635 nm), beta sp (525 nm), alpha(635/450), and SSA were 1791.66 ng m- 3, 82.37 Mm- 1 at 450 nm, 102.57 Mm- 1 at 525 nm, 126.60 Mm-1 at 635 nm, 0.23, 1.47, and 0.92, respectively. Compared with values obtained in 2013, Na decreased by 60% and Ma decreased by 45%, but the scattering coefficients increased in different degrees. In the vertical direction, aerosol concentrations were higher at lower altitudes, decreasing with height. Vertical profiles of Sigma sp, beta sp, alpha(635/450), and BCc measured during the six flights were examined. Two peaks in Na were identified near the top of the boundary layer and between 2000 and 2200 m. Fine particles with EDa smaller than 0.8 mu m are dominant in the boundary layer and coarse aerosols existed aloft. Aerosol scattering properties and BCc in the lowest layer of the atmosphere contributed the most to the total aerosol radiative forcing. SSA values were greater than 0.9 below 2500 m, with lower values at higher levels of the atmosphere. On lightly foggy days, SSA values were greater than 0.9, and aerosols played a cooling role in the atmosphere. On hazy days, lowerlevel SSA values were generally greater than 0.85, with aerosols likely having a warming effect on the atmosphere. 48-hour backward trajectories of air masses during the observation days showed that the majority of aerosol particles in the lower atmosphere originated from local or regional pollution emissions, contributing the most to the total aerosol loading and leading to high values of aerosol concentration and radiative forcing.

The vertical distributions of BC mass concentration (m(BC)) during a winter pollution period in 2017 over Chengdu, a megacity in the Sichuan Basin, China, were measured by a micro-aethalometer equipped on a tethered balloon. This observation experienced severe air pollution with an averaged ground BC of 11.1 mu g.m(-3), which is higher than two times the annual mean in Chengdu for 2018. The available 68 BC vertical profiles are grouped in to five types: Type A (18%) is the uniform vertical distribution of BC with an unrecognizable mixing layer (ML) height; BC in Type B (26%) is also uniformly distributed in the ML while decreases rapidly above the ML; Type C (7%) is a unimodal distribution with BC peak within the ML when the suspended temperature inversion forms; BC in Type D (29%) is accumulated in the near-ground layer and quickly decreases with height; Type E (20%) is the bimodal or trimodal distribution with BC peaks around the top of ML. Types A and B dominate from noon to afternoon, and Types C-E play critical roles during the evening and night. The different vertical patterns of BC are mainly associated with the evolution of the ML and the local emissions. For all the five types, the calculated radiative forcing of BC (f(BC)) is negative at the surface but positive at the top of profile (TOP), indicating the net absorption of radiation by the atmosphere due to BC. The absolute values of f(BC) at the surface and the TOP are increased with the increase of columnar BC loading, and there is no significant difference in f(BC) at the TOP and the surface among different patterns when the same BC loading is considered. However, the vertical distribution of atmospheric heating rate contributed by BC (h(BC)) is highly related to BC's vertical profile. The uniform distributed BC can result in a positive gradient of h(BC) with altitude, and thus, enhance the stability of the atmosphere. The plateau terrain induced small-scale secondary circulation and relatively lower thermal inversion in the west of the Sichuan basin have an essential effect on the vertical distribution of aerosols and can contribute to an accumulation of aerosols at 0.8-1.4 km above ground level. This study would hopefully have a preliminary understanding of the vertical distribution of BC in the Sichuan Basin, and a vital implication for accurately estimating direct radiative forcing by BC in this region.

The lack of light-absorbing aerosols vertical distributions data largely limited to revealing the formation mechanism of severe haze pollution in Chinese cities. Based on the synchronous measurements of size-resolved carbonaceous aerosols and meteorological data at near surface level and hilltop (about 620 m above the valley) in Lanzhou of northwest China, this study compared organic and elemental carbon (OC, EC) size distributions at the two altitudes and revealed the key influencing factors in a typical urban valley, China. The winter OC size distributions were typically bimodal with two comparable peaks in the accumulation and coarse modes, while those in summer were unimodal with the highest value in the size bin of 4.7-5.8 mu m. The size-resolved OC and EC at near the surface were significantly higher than those at the hilltop. The difference (concentrations and size distributions) of OC and EC between the surface and hilltop in summer was much smaller than that in winter due to stronger vertical mixing and larger summer SOC contributions at the hilltop. The winds paralleling with running urban valley were conducive to dispersing the air pollutants from near the surface to the upper air. The roles of horizontal and vertical dispersions to carbonaceous aerosols were comparable at near the surface, while horizontal dispersion was more important at the hilltop. Furthermore, the vertical dispersion was a main factor controlling size-resolved carbonaceous aerosols under highly polluted conditions in a typical urban valley. This study will provide the basis for regulation of severe haze pollution over complex terrain.

This study investigates the impacts of black carbon (BC) properties (vertical concentration, shape, size, and mixing state) and atmospheric variables (cloud and aerosol loading, surface albedo, and solar zenith angle) on BC radiative effects. Observations from aircraft measurements, lidar, and the Aerosol Robotic Network (AERONET) are used to constrain BC and aerosol properties. The library for radiative transfer (Libradtran) model is used to calculate BC radiative forcing (RF). BC optical properties are obtained from numerical modeling with aggregate or spherical structures and different size distributions. By modifying the optical properties, different BC geometries and size distributions result in uncertainties in RF and heating rate less than 30%, while the uncertainty in heating rate due to different BC mixing states is as large as similar to 80%. The vertical distribution of BC concentrations explains less than 10% of the relative differences in RF and heating rate in the atmosphere, but can induce different heating rate vertical profiles, thus different planetary boundary layer (PBL) stabilities. Due to the significant influence of cloudy and aerosol conditions on incident solar radiation, atmospheric conditions play an important role in determining the BC heating rate. Meanwhile, the effects of surface albedo and solar zenith angle on the BC heating rate are most significantly near the surface. Taking the above factors into account, we introduce an empirical approximation of the BC heating rate to estimate its influence on the atmosphere. With the simple formula, the BC heating rate for a particular atmospheric layer can be approximated when the vertical condition is known, and this can be further applied to determine whether BC promotes or suppresses PBL development. Considering the importance of the BC vertical concentration in its heating rate, we suggest that light-absorbing aerosols and their vertical distributions must be better measured and modeled to improve the understanding of their radiative effects and interaction with PBL.