Vegetation Properties Research Articles

Topographic Drivers of Permafrost Organic Carbon Accumulation on the Northern Qinghai–Tibet Plateau

ABSTRACTLarge amounts of soil organic carbon (SOC) have accumulated over thousands of years in the northern permafrost regions. However, the SOC accumulation rates and the effects of topography, vegetation, and soil properties on SOC storage remain poorly constrained, leading to large uncertainties in the estimation of SOC storage and its response to warming. Here, we examined SOC stocks, densities, and accumulation rates using field sampling and radiometric dating in areas with different topographic parameters on the northern Qinghai–Tibet Plateau. Results show that SOC density and stock increases with elevation on south‐facing slopes but decreases with elevation on north‐facing slopes. The carbon accumulation rates in the upper 6 m soil are highest (16.32 g C m−2 year−1) in the north‐facing alpine wet meadow and lowest (1.07 g C m−2 year−1) in the south‐facing alpine steppe. Elevation‐, slope‐, and slope aspect‐induced variations in soil properties and vegetation type are the main factors controlling the spatial SOC distribution. These results imply that the topography strongly affects the spatial heterogeneity of SOC in mountainous permafrost regions. Overall, our findings highlight that topographic factors should be further integrated into carbon models of carbon responses to climate change in permafrost‐affected soils.

GPS tracking reveals koalas Phascolarctos cinereus use mosaics of different forest ages after environmentally regulated timber harvesting

AbstractAn accurate picture of an animal's home range is fundamental for quantifying habitat quality and response to disturbance. When combined with remote sensing of vegetation attributes, there is potential to assess habitat selection at high resolution. We used a high‐quality GPS‐collaring data set (> 12 500 fixes) from 10 koalas Phascolarctos cinereus and a canopy height model derived from LiDAR in multiple‐use forests harvested for timber 5–10 years previously. Our aim was to assess how individual koalas use the forest mosaic created by timber harvesting by quantifying home ranges and habitat selection of different forest age/height classes created by past harvesting. We found that koalas maintained a stable home range over the average of 7 months of tracking. On average, there was 95% overlap for individuals among seasons, illustrating high site fidelity in the regenerating forest. Also, there were no apparent shifts during the intense drought of spring 2019. Male home ranges (64 ha) were three times the size of females (21 ha). Core areas were considerably smaller, ranging from 15 (male) to 6 ha (female). Three forest age/height classes were defined from LiDAR: (i) harvest – regeneration <14 m, (ii) harvest – retained trees ≥14 m and (iii) harvest – exclusion trees ≥14 m (zones excluded from harvesting for environmental protection). Home ranges covered the mosaic of forest classes and mixed models revealed no selection of forest class based on use versus availability. High site fidelity with no clear selection for forest age/height class (i.e. harvested and non‐harvested patches) confirms that resource quality in the home range remained sufficient for breeding koalas in the post‐harvest landscape. Ongoing monitoring of koalas is required to ensure that environmental protections are effective in maintaining koala populations in the face of additional disturbances from fire and climate change.

Experimental Study of Vegetative Properties in Zeolite–Biochar-Improved Ecological Revetment Substrates

The vegetation of the ecological substrate plays a crucial role in restoring shoreline ecology. This study focused on using zeolite and biochar as substrate modifiers, specifically utilizing the Cynodon dactylon from Central China for vegetation. A pot vegetation experiment was carried out to compare the effects of different ratios of zeolite and biochar. The vegetation indices, including germination index, plant height, and coverage rate, were analyzed and discussed. The results revealed that zeolite primarily influenced the germination index of Cynodon dactylon, while biochar had a more significant impact on germination percentage, germination energy, plant height, and coverage rate. This study discovered that the seed germination effect of the improved substrate initially increased with zeolite content and then decreased. The average germination percentage was 63.96%. Conversely, it decreased with an increase in biochar content, resulting in an average germination percentage of 55.45%. Zeolite and biochar caused a decrease and increase in substrate pH by −0.11 and 0.4 on average, respectively. The germination of each substrate showed a negative correlation with pH. Additionally, the average coverage and plant height decreased with an increase in biochar content. However, the inclusion of 6% zeolite led to an increase in coverage and plant height. Specifically, the average plant height increased by 3.92 cm and the coverage by 7.48%. Our research identified the optimal ratio of zeolite and biochar as 6% zeolite and 0% biochar, showcasing good overall vegetative properties. These findings offer insights for further understanding the vegetative effects of zeolite–biochar-modified substrates and optimizing substrate schemes for ecological vegetation projects.

Changes in vegetation and soil coupling induced by biocrusts: New thinking on the segmented control of soil and water loss in the Loess Plateau, China

Biocrust is widely distributed on land surfaces worldwide, it is especially important in arid and semi-arid areas with serious soil erosion; however, the impact of biocrust on vegetation soil coupling in complex topography has not been reported. This study revealed the variation of biocrust coverage in different slope direction and gradient, and the fluctuation of vegetation and subsoil physicochemical properties mediated by it. The SEM (Structural equation modeling) further investigated the effects and pathways of biocrusts on soil-vegetation coupling conditions. The results indicated that the degree of coupling of the sunny slope showed a trend of gradual dispersion with a starting point of 1 as the slope decreased, whereas the coupling degree of the shady slope showed an overall process of gradual aggregation towards 1. In addition, the SEM showed that the moss on sunny slopes affected degree by nourishing vegetation (47%) and the effect of soil on coupling degree is more obvious (23%) on shady slopes. As for lichen system, it affected the coupling degree (27%) by itself on sunny slopes, and it further influencing coupling on shady slopes through the mediation of vegetation (54%). Our research results provide a theoretical of the coupling of soil and vegetation in middle slope (45°) is best in two directions, and provide a reference for the segmented management of soil erosion under continuous slope changes.

Effects of groundwater level decline on soil‐vegetation system in semiarid grassland influenced by coal mining

AbstractAlthough it is well known that groundwater significantly influences the plant communities, there have been few studies on how the soil and plant communities respond to a rapid decline of groundwater in a short time affected by coal mining. This paper focuses on the examination of changes in groundwater depth before and after coal mining and the soil‐vegetation response in a typical semi‐arid grassland coal mine area of Hulunbuir Steppe, Northeastern China. The IsoSource model, based on the dual stable isotopes of δ D and δ18O, was employed to estimate groundwater contributions to shallow soil (0–100 cm) water under different groundwater depths. The results revealed that groundwater was the dominant water source (75.7% ± 17.1%) for shallow soil water when the groundwater depth is less than 4 m, indicating that 4 m is a threshold in groundwater depth, separating groundwater‐dependent, and precipitation‐driven vegetation system in the study area. Secondly, a strong nonlinear response was observed between vegetation species, height, coverage, and the decline in groundwater. The vegetation properties were found to be the lowest in the areas where groundwater depth increased from 1.5–4 m to 4–28 m before and after coal mining. Finally, the groundwater level decline in the mining area significantly influenced the groundwater‐dependent vegetation ecosystem, the soil cation exchange capacity and organic matter reduced lead to the degradation of plant communities and the transition of mesophytes to xerophytes. Besides, the soil‐vegetation system in the non‐groundwater‐dependent area has no obvious response to the groundwater decline. These results suggest that caution should be exercised when mining in groundwater‐dependent ecosystem regions.

Impacts of mining on vegetation phenology and sensitivity assessment of spectral vegetation indices to mining activities in arid/semi-arid areas

Measuring the impact of mining activities on vegetation phenology and assessing the sensitivity of vegetation indices (VIs) to it are crucial for understanding land degradation in mining areas and enhancing the carbon sink capacity following the ecological restoration of mines. To this end, we have developed a novel technical framework to quantify the impact of mining activities on vegetation, and applied it to the Bainaimiao copper mining area in Inner Mongolia. Phenological indices are extracted based on the VI time series data of Sentinel-2, and changes in phenological differences in various directions are used to quantify the impact of mining activities on vegetation. Finally, indicators such as mean difference, standard deviation, index value distribution interval, and concentration of index value distribution were selected to assess the sensitivity of the Enhanced Vegetation Index (EVI), Green Chlorophyll Index (GCI), Global Environmental Monitoring Index (GEMI), Green Normalized Difference Vegetation Index (GNDVI), Normalized Difference Vegetation Index (NDVI), Renormalized Difference Vegetation Index (RDVI), Red-Edge Chlorophyll Index (RECI), and Soil-Adjusted Vegetation Index (SAVI) to mining activities. The results of the study show that the impact of mining activities on surrounding vegetation extends to an area three times larger than the actual mining activity area. When compared with the reference and unaffected areas, the affected area experienced a delay of approximately 10 days in seasonal vegetation development. Environmental pollution caused by the tailings pond was identified as the primary factor influencing this delay. Significant variations in the sensitivity of each VI to assess mining activities in arid/semi-arid areas were observed. Notably, GCI, GNDVI and RDVI displayed relatively high sensitivity to discrepancies in the spectral attributes of vegetation within the affected area, while SAVI reflected the overall spectral stability of the vegetation in the affected area. The research findings have the potential to provide valuable technical guidance for holistic environmental management in mining areas and hold great significance in preventing further land degradation and supporting ecological restoration in mining areas.

CONSUMER PREFERENCE TOWARDS THE ATTRIBUTES OF AQUAPONICS PRODUCTS AT PT. TANIKOTA

The increasing awareness of healthy lifestyle among the public has made consumers more selective in choosing their food, particularly vegetables. Aquaponic vegetable products, which are free from pesticides, have emerged as an alternative for health-conscious consumers. This study aimed to identify the characteristics of consumers who purchase aquaponic vegetables based on product attributes at PT. Tanikota and to determine the ranking of attributes of aquaponic vegetables according to consumer preferences. The research method employed in this study was a case study, using a whole population of 70 aquaponic vegetable consumers at PT. Tanikota as the respondents. Data were analyzed using descriptive analysis of frequency distribution. The results of the study revealed that the characteristics of consumers who buy aquaponic vegetables at PT. Tanikota were generally women aged 26-35 years, holding an undergraduate degree, with 3 family dependents, employed in private sectors, and having an income range of 2,600,000-Rp 5,200,000/month. The attributes of aquaponic vegetables at PT. Tanikota were ranked based on consumer preferences, with the level of freshness of vegetables, variety of vegetables, color of vegetables, method of payment, method of purchase, physical form of vegetables, vegetable size, distance, vegetable packaging, and the price of vegetables, respectively. The lower rank of price attributes can be attributed to the lack of aquaponic vegetable cultivation in the city of Bandung, which makes it difficult for consumers to compare the prices offered by PT. Tanikota with those offered by other companies.

Different responses of lipids and lignin phenols to nitrogen addition in meadow grassland soil

PurposeNitrogen (N) enrichment can affect the composition and stability of soil organic carbon (SOC) pools by altering vegetation and soil properties. However, the response of plant-derived carbon components in soil to different N addition levels is unclear. We investigated the changes and potential driving processes of plant-derived carbon components (especially lignins and lipids) in meadow grassland soils under long-term N addition in eastern Inner Mongolia, China.Materials and methodsBiomarker technology was utilised to analyse changes in plant-derived carbon components (C>20 free lipids, bound lipids, and lignin phenols) in soil under different N addition levels, including changes in soil chemical properties, enzyme activity, plant biomass, and diversity under N addition, as well as the specific pathways involved.Results and discussionWe found that high levels of N addition significantly reduced the concentration of soil lignin phenols whereas increased the accumulation of lipids (free and bound lipids). Compared with changes in plant biomass and diversity, soil chemical properties and enzyme activity play a more significant role in regulating the accumulation and degradation of plant-derived carbon. Structural equation modelling (SEM) showed that decreases in lignin phenol concentration were related to specific biochemical decomposition processes (increased polyphenol oxidase activity and decreased C/N). The increase in lipids associated with the protective effects of minerals mediated by pH.ConclusionsIn general, plant-derived carbon components showed inconsistent responses to N addition, lignin phenol concentration decreased and lipid concentration increased, which was mainly related to the change of soil biochemical properties. Plant-derived carbon components only showed significant changes under high N addition levels. Furthermore, our research indicates that SOC sequestration and functioning are highly dependent on soil biochemical properties, which weakens the influence of changes in plant carbon input on soil carbon storage.

A New Vegetation Observable Derived from Spaceborne GNSS-R and Its Application to Vegetation Water Content Retrieval

In this study, a new vegetation observable derived from spaceborne Global Navigation Satellite System-Reflectometry (GNSS-R) was developed. Firstly, a linear relationship between the Cyclone Global Navigation Satellite System (CYGNSS) reflectivity and soil moisture was derived based on the tau-omega (τ−w) model. The intercept and slope of this linear function were associated with the vegetation properties. Moreover, the intercept is not affected by soil moisture and depends only on vegetation properties. Secondly, to validate the new observable, the intercept demonstrated a significant correlation with vegetation water content (VWC), with the highest correlation coefficient of 0.742. Based on the intercept and slope, a linear model and an artificial neural network (ANN) model were established to retrieve VWC by combining geographical location and land cover information. The correlation coefficient and root-mean-square error (RMSE) of VWC retrieval based on the linear model were 0.795 and 2.155 kg/m2, respectively. The correlation coefficient and RMSE for the ANN model were 0.940 and 1.392 kg/m2, respectively. Compared with the linear model, the ANN model greatly improves the global VWC retrieval in accuracy, especially in areas with poor linear model retrieval results. Therefore, compared with conventional remote sensing techniques, the spaceborne GNSS-R can provide a new and effective approach to global VWC monitoring.

Elevation gradients alter vegetation attributes in mountain ecosystems of eastern Himalaya, India

The present study describes how vegetation (the tree layer) is shaped along the elevation gradients in the eastern part of the Indian Himalayan Region. Various vegetation attributes, distribution, population structure, and regeneration patterns of 75 tree species belonging to 31 families were studied. Tree species richness shows a low plateau (peaked between 1,300–1,500 m) with a linearly decreasing pattern above 1,500 m asl. Ericaceae was found as the dominant family, followed by Lauraceae and Rosaceae. The distributional pattern of species-to-genera ratio (S/G) did not follow any particular trends, while β-diversity increased along the elevation gradient. The Margalef index of species richness, the Menheink index of species richness, and the Fisher alpha were found to be highest at lower altitudes (1,000–1,500 m), while the Simpson index was highest at middle altitudes (2,600–3,000 m). Random distribution was shown by maximum tree species (47.3%), followed by a contagious distribution (42.9%), and regular distribution (10.8%). The regeneration of tree species was found to be good with a healthier number of seedlings (10.2%), fair (43.5%), poor (30.3%), while 16% were observed not regenerating. Acer laevigatum (1,500 m), Prunus nepalensis (3,300 m), Viburnum sympodiale (3,400 m) were among the new regenerating species at the respective altitudes. The population structure of tree species in terms of proportion of individuals in seedlings, saplings, and the adult class varied in all the elevation transects. Species with better regeneration on upper distribution limits have been recognized as probable for upward movement.

Precipitation and plant community-weighted mean traits determine total transpirable soil water in a desert grassland

The desert grassland has low precipitation, high evaporation and a limited soil water supply. Thus the tension between water shortage and sustainable vegetation restoration is increasingly evident. Change in total transpirable soil water (TTSW) reflects the water utilization and extraction capacity of plant communities, which are the basis for maintaining productivity and stability in communities, as well as the key ecological processes alleviating the above tension. Change in TTSW is influenced by precipitation, vegetation and soil. Quantifying the relative contribution of these factors to change in TTSW is key to the sustainable restoration of desert grassland. However, the current understanding of such effects remains limited. This study examined four typical plant communities in the Ningxia desert grassland, monitoring soil water content and evaluating plant community characteristics and diversity over three consecutive years. Using redundancy analysis and hierarchical partitioning methods, the influence of annual precipitation, vegetation (functional and species diversity, community characteristics) and soil physical properties on TTSW variation were investigated. Findings revealed: (1) The factors contributing to TTSW variation were annual precipitation (41 %-68 %,), vegetation (29 %-45 %), and soil physical properties (0 %-6.7 %). Specifically, community-weighted mean traits (CWM) and functional diversity (FD) explained TTSW variation by 24–37 % and 0.25–11 % respectively. In Gramineae communities, the influence of annual precipitation and vegetation on TTSW variation was consistent across soil depths. However, in degraded Sophora alopecuroides + Artemisia scoparia (SA) communities, the influence of vegetation (CWM, FD, community composition and community function) on TTSW variation was more pronounced in shallow soils (45 %) than in deeper soils (33 %), while annual precipitation effects were more substantial in the deep soil layers (66 %) than in the shallow soil layers (42 %). (2) Annual precipitation and CWM were the main biological and abiotic factors affecting TTSW. Interestingly, increased annual precipitation was negatively correlated with TTSW. Similarly, the primary controlling factor, CWM, also showed a significant negative relationship with TTSW. This relationship varied across community types and could be linear or quadratic, highlighting the need to understand the selection effects mediated by CWM in ensuring sustainable vegetation restoration. This research offers insights into the relationship between plant functional diversity and soil water retention function.

Modeling Land–Atmosphere Interactions over Semiarid Plains in Morocco: In-Depth Assessment of GCM Stretched-Grid Simulations Using In Situ Data

Abstract Land surface–atmosphere interactions are a key component of climate modeling. They are particularly critical to understand and anticipate the climate and the water resources over the semiarid and arid North African regions. This study uses in situ observations to assess the ability of the IPSL-CM global climate model to simulate the land–atmosphere interactions over the Moroccan semiarid plains. A specific configuration with a grid refinement over the Haouz Plain, near Marrakech, and nudging outside Morocco has been performed to properly assess the model’s performances. To ensure reliable model–observation comparisons despite the fact that station measurements are not representative of a mesh-size area, we carried out experiments with adapted vegetation properties. Results show that the CMIP6 version of the model’s physics represents the near-surface climate over the Haouz Plain reasonably well. Nonetheless, the simulation exhibits a nocturnal warm bias, and the wind speed is overestimated in tree-covered meshes and underestimated in the wheat-covered region. Further sensitivity experiments reveal that LAI-dependent parameterization of roughness length leads to a strong surface wind drag and to underestimated land surface atmosphere thermal coupling. Setting the roughness heights to the observed values improves the wind speed and, to a lesser extent, the nocturnal temperature. A low bias in latent heat flux and soil moisture coinciding with a pronounced diurnal warm bias at the surface is still present in our simulations. Including a first-order irrigation parameterization yields more realistic simulated evapotranspiration flux and daytime skin surface temperatures. This result raises the importance of accounting for the irrigation process in present and future climate simulations over Moroccan agricultural areas.

Characteristics of Soil Chemical Properties in Several Types of Oil Palm (Elaeis guineensis Jacq.) Land and Shrubs in Negeri Lama Seberang Village (Case Study of Lower Bilah Watershed)

The Bilah Sub-Watershed area includes areas that have somewhat critical or semi-critical land so that land use is the result of human efforts in managing the available resources to meet their various needs. This often results in land use not being in accordance with its capabilities. This research aims to examine the chemical properties of several vegetation in Negeri Lama Seberang Village, Bilah Hilir District, Labuhanbatu Regency. The research was carried out from December to March 2024 using a survey method. Soil samples were taken at 3 points for each vegetation and different slopes at depths of 1-10 cm and 10-20 cm using a simple random method. The soil parameters measured were soil acidity (electrometry), soil organic carbon content (Walkley and Black), and soil texture (bouyoucos hydrometer). Soil analysis was carried out at the Laboratory of the Faculty of Agriculture, University of North Sumatra. The results of this research show that on a slope of 0-8% the average soil pH value is 4.61% and organic C is 1.04%, while on a slope of 8-15% the average soil pH value is 4.46% and C -organic 0.91%. On a slope of 0-8% the average value of the clay fraction is 20.27%, the dust fraction is 15.02% and the sand fraction is 64.41%, while on a slope of 8-15% the average value of the clay fraction is 27.48%, the dust fraction 19.87%, and sand fraction 52.63%.

Sampling Protocol for Measuring Mean Diameter at Breast Height of Forked Urban Trees

The sustainable management of urban green areas requires clear and efficient protocols for measuring the biometric properties of tree vegetation. Specifically, operational in situ sampling solutions are essential to inventory forked (multi-stemmed) trees. This study aimed to assess the efficiency of two different sampling protocols for mean tree diameter at breast height (DBH) measurement of forked urban trees. The protocols were tested on a dataset of 76 forked trees, each having more than three stems and sampled in urban areas of Kyiv, Ukraine. First, we tested the efficiency of mean tree DBH estimations using measurements of randomly selected one, two, or three stems (random sampling, or RSM). Second, we examined different combinations of the thinnest, thickest, and average stems (identified visually) for each tree to estimate mean tree DBH (targeted sampling, or TSM). The distributions of mean tree DBH and root mean square errors (RMSE) were utilized to compare the utility of the two approaches. The TSM of three stems (the thinnest, thickest, and average) provided the highest accuracy of mean tree DBH estimation (RMSE% = 6.3% of the mean), compared to the RSM (RMSE% = 12.1%). The TSM of the four thickest stems demonstrated the overestimation of mean tree DBH for forked trees with five or more stems. Accurate mean tree DBH estimates can be derived with negligible systematic errors applying the RSM over a large number of measured trees. However, these estimates will not likely match the measurements from previous inventories due to random stem selection. We recommend using the TSM with measuring three specific stems as a balanced solution in terms of estimation accuracy, bias, and time costs.

The Influence of Human Activity and Environmental Factors on Gully Erosion

Gully erosion, far from confined to specific terrains like badlands or mountainous areas, stands as a global issue contributing significantly to land degradation across various soil types susceptible to crusting or piping. Even after initial triggers cease, formed gullies can persistently generate sediment. This study delves into the multifaceted influences of geology, climate, slope morphology, vegetation, human impact, and soil properties on gully development and broader soil erosion. Drawing from empirical examples globally and locally, it underscores the pivotal role of local soil characteristics in propagating erosion, particularly the gully variant. Anthropogenic factors, especially land use practices and their impact on vegetation, weigh heavily. Rampant deforestation coupled with insufficient re-vegetation or afforestation initiatives have exacerbated the looming erosion threats, contributing to catastrophic consequences. Despite the effectiveness of various strategies in preventing and addressing gully erosion, their sustained implementation on a large scale remains elusive. Thus, research priorities must encompass sub-surface flow erosion mechanisms, predictive models, and the intricate dynamics influencing farmers' adoption or rejection of conservation strategies. To combat soil erosion comprehensively, a holistic approach to soil conservation becomes imperative. This entails employing hydrological or bioenvironmental processes to regulate overland flow and curb excessive runoff. Prioritizing these aspects can inform more robust strategies for soil conservation, mitigating the pervasive impact of erosion on our lands. Keywords: Influence, Human, Activity, Environmental Factors and Gully Erosion

Ecological responses to hydrological connectivity in grassland riparian zones: Insights from vegetation and ground-dwelling arthropods

Riparian wetlands have suffered from degradation due to global climate change and human activities, which can alter flora and fauna community patterns and disrupt material cycles in the riparian zones. Hydrological connectivity identified by functional and structural connectivity is an important driving force of riparian ecosystems. However, the role of hydrological connectivity in linking riparian hydrology and ecology remains unclear, especially in dryland rivers. By taking the riparian zone of the Xilin River in Eurasian steppe as an example, the functional connectivity was represented by the groundwater depth in the riparian zones. The structural connectivity was quantified by integrating the soil, and vegetation properties of the riparian zone. The structural connectivity decreased from upstream to downstream. Laterally, the highest structural connectivity was found in the riparian zone 25 m away from the river channel. The abundance of three groups of ground-dwelling arthropods (except Araneae) showed a threshold behavior in response to the functional connectivity, with the highest abundance occurring in the medium level of functional connectivity. Both vegetation biomass and ground-dwelling arthropod abundance were significantly and positively correlated to the structural connectivity strength. The results of structural equation models (SEMs) also indicated that structural connectivity was a key factor affecting vegetation and ground-dwelling arthropod abundance. The results underscore the essential function of hydrological connectivity in maintaining the biodiversity in the riparian zones. The study provides a scientific reference of riparian-zone restoration based on hydrological connectivity.

Altitudinal patterns of alpine soil ammonia-oxidizing community structure and potential nitrification rate.

Nitrogen availability limits the net primary productivity in alpine meadows on the Qinghai-Tibetan Plateau, which is regulated by ammonia-oxidizing microorganisms. However, little is known about the elevational patterns of soil ammonia oxidizers in alpine meadows. Here, we investigated the potential nitrification rate (PNR), abundance, and community diversity of soil ammonia-oxidizing microorganisms along the altitudinal gradient between 3,200 and 4,200 m in Qinghai-Tibetan alpine meadows. We found that both PNR and amoA gene abundance declined from 3,400 to 4,200 m but lowered at 3,200 m, possibly due to intense substrate competition and biological nitrification inhibition from grasses. The primary contributors to soil nitrification were ammonia-oxidizing archaea (AOA), and their proportionate share of soil nitrification increased with altitude in comparison to ammonia-oxidizing bacteria (AOB). The alpha diversity of AOA increased by higher temperature and plant richness at low elevations, while decreased by higher moisture and low legume biomass at middle elevations. In contrast, the alpha diversity of AOB increased along elevation. The elevational patterns of AOA and AOB communities were primarily driven by temperature, soil moisture, and vegetation. These findings suggest that elevation-induced climate changes, such as shifts in temperature and water conditions, could potentially alter the soil nitrification process in alpine meadows through changes in vegetation and soil properties, which provide new insights into how soil ammonia oxidizers respond to climate change in alpine meadows.IMPORTANCEThe importance of this study is revealing that elevational patterns and nitrification contributions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities were primarily driven by temperature, soil moisture, and vegetation. Compared to AOB, the relative contribution of AOA to soil nitrification increased at higher elevations. The research highlights the potential impact of elevation-induced climate change on nitrification processes in alpine meadows, mediated by alterations in vegetation and soil properties. By providing new insights into how ammonia oxidizers respond to climate change, this study contributes valuable knowledge to the field of microbial ecology and helps predict ecological responses to environmental changes in alpine meadows.

A new approach for spatializing the Canadian National Forest Inventory (SCANFI) using Landsat dense time series

Accurate and fine-scale forest data are essential to improve natural resource management, particularly in the face of climate change. Here, we present SCANFI, the Spatialized CAnadian National Forest Inventory, which provides coherent, 30 m resolution 2020 wall-to-wall maps of forest attributes (land cover type, canopy height, crown closure, aboveground tree biomass, and main species composition). These maps were developed using the NFI photo-plot dataset, a systematic regular sample grid of photo-interpreted high-resolution imagery covering all of Canada's non-arctic landmass. SCANFI was produced using temporally harmonized summer and winter Landsat spectral imagery along with hundreds of tile-level regional models based on a multiresponse k-nearest neighbours and random forest imputation method. This tile-level approach revealed the importance of radiometric variables in predicting vegetation attributes, namely winter radiometry, as the large-scale climate gradients were controlled at the tile-level. SCANFI was validated with rigorous cross-validation analyses, which revealed robust model performance for structural attributes (biomass R2 = 0.76; crown closure R2 = 0.82; height R2 = 0.78) and tree species cover (e.g., Douglas fir R2 = 0.60). SCANFI attributes were also validated with several independent external products, ranging from ground plot-based tree species cover (e.g., black spruce R2 = 0.53) to satellite LiDAR height data products (e.g., crown closure R2 = 0.71). SCANFI total aboveground biomass trends also followed those published by other studies. The methodology presented herein can be used to map time series of these attributes, identify the original training points used to make any given prediction, as well as map additional variables associated with the NFI photo-plots that are challenging to map using traditional remote sensing approaches.

Do Mature Quercus aliena Primarily Use Deep Soil Water?

Seasonal drought events induced by climate change have exacerbated the water deficit in trees. This is particularly pronounced in mature trees with considerable heights and extensive branches, where the long water transport distance leads to a reduction in hydraulic transportation efficiency. Therefore, investigating the water uptake patterns of mature trees is essential to enhance their growth and resilience to climate change. However, previous studies have predominantly focused on trees aged 10–60 years, with limited research on the water uptake patterns of trees over 60 years old. In this study, we employed hydrogen and oxygen stable isotopes coupled with the MixSIAR model to determine the water uptake patterns of mature Quercus aliena var. acuteserrata (40–60 years, 60–90 years, 120–150 years, >150 years) during the growing seasons of 2021 and 2022 in Baotianman Nature Reserve, Henan Province, China. Additionally, we utilized a random forest model to quantify the relative contributions of vegetation (fine root biomass) and soil properties (soil moisture, bulk density, total porosity, field capacity, and soil texture) to the water uptake patterns of Q. aliena. Our findings demonstrate that most mature Q. aliena predominantly extracted deep soil water (60–100 cm) in the early growing season, but shifted towards utilizing shallow soil water (0–40 cm) in the late growing season. The water uptake pattern of mature Q. aliena was primarily regulated by soil moisture. These results reveal that mature Q. aliena trees exhibit a flexible water use strategy, enabling them to cope with seasonal drought by altering the soil depth from which they extract water. In the future, in the process of the cultivation and conservation of mature oak trees, surface soil irrigation can be increased to prevent tree mortality resulting from water deficit during drought conditions.

Combining approaches for environmental assessment of rehabilitated gold‐mining areas in the Eastern Amazon

AbstractMonitoring key soil and vegetation attributes in mining areas under environmental rehabilitation is essential to ensure that the intervention techniques are effective. There are several approaches to monitoring mining areas and their integration is necessary to process large amounts of information. Thus, this study aimed to (i) assess soil multi‐contamination with potentially toxic elements (PTE) and human health risks; (ii) obtain a soil quality index with soil fertility data; (iii) calculate spectral index; (iv) show rehabilitation status based on vegetation attributes, and (v) compile these indices in a single measure. Four tailings' ponds (TPs), two waste piles (WPs), and an area of native forest from a gold mine in the Carajás National Forest were evaluated. Soil quality and vegetation cover are good in forest areas, with no evidence of PTE contamination. On the other hand, the TPs have poor fertility and vegetation cover, as well as higher levels of PTE. Human health risk indices obtained for all PTE were lower than 1, indicating a low risk to human health. The results of integrating the different indices suggest that the environmental conditions of the WPs are better than those of the TPs, which are still far from the environmental conditions of native areas. Soil attributes and vegetation development in TPs areas could be enhanced by the incorporation of organic materials and fertilizers and by planting species with phytoremediation potential. Finally, the integrative approach of the different indices proved to be useful in assessing the rehabilitation progress of the areas.