Resource storage is a critical component of plant life history. While the storage of nonstructural carbohydrates in wood has been studied extensively, the multiple functions of mineral nutrient storage have received much less attention. Here, we highlight the size of wood nutrient pools, a primary determinant of whole-plant nutrient use efficiency, and a substantial fraction of ecosystem nutrient budgets, particularly tropical forests. Wood nutrient concentrations also show exceptional interspecific variation, even among co-occurring plant species, yet how they align with other plant functional traits and fit into existing trait economic spectra is unclear. We review the chemical forms and location of nutrient pools in bark and sapwood, and the evidence that nutrient remobilization from sapwood is associated with mast reproduction, seasonal leaf flush, and the capacity to resprout following damage. We also emphasize the role wood nutrients are likely to play in determining decomposition rates. Given the magnitude of wood nutrient stocks, and the importance of tissue stoichiometry to forest productivity, a key unresolved question is whether investment in wood nutrients is a relatively fixed trait, or conversely whether under global change plants will adjust nutrient allocation to wood depending on carbon gain and nutrient supply.

Biocrusts play an essential role in maintaining ecosystem stability, which is common in arid and semi-arid areas. Although there have been some previous studies on the stoichiometry of biocrust subsoil in grazing systems, further research is needed to assess the effects of varying grazing intensities. Four grazing gradients were established to investigate the change mechanism of biocrust subsoil stoichiometry under grazing conditions, considering its seasonal response. These findings revealed that biocrusts' coverage and their chlorophyll content showed a parabolic trend of increasing and then decreasing with the increase in grazing intensity. At the same time, their standard response thresholds to grazing intensity ranged from 2.67 to 5.33 sheep/ha. Moreover, the premise that the biocrust is damaged by grazing trampling has become a consensus; our study found that the biocrust still played an important role, although its structure was destroyed because of its greenness (BG) increased. The influence of grazing intensity on the biocrust subsoil stoichiometry is unquestionable; in addition, they are influenced by a combination of vegetation (10% and 19%) and environmental influences (6% and 18%). Furthermore, it was observed that these changes did not compensate for the reproduction and development of biocrusts in grazing-induced trampling damage. In this study, the integrated consideration of biocrusts into the grazing system fully affirmed its essential role. Additionally, it clarified the pathways and effect of grazing on biocrusts subsoil stoichiometry, providing a new perspective and reference for developing grazing strategy on the Loess Plateau.

Coastal wetlands are extremely vulnerable to both marine damage and human activities. In order to protect these wetlands, many artificial seawalls have been constructed. However, studies are required to understand how coastal wetlands will evolve under the influence of artificial seawalls. Therefore, to understand this succession process of plants and their adaptation to habitats divided by seawalls, two different habitats inside and outside the seawalls were selected in Laizhou Bay, China. The results showed that there were 5 plant species outside the seawalls that were lower than the 13 species inside. Additionally, the dominant plant species were varied between the two habitats, with mostly annual herbs observed outside the seawalls and perennial shrubs inside. Soil salinity was higher outside the seawalls, which was the key impact factor of soil nutrient differences. The distribution of annual and perennial species may be constrained by spatial differences in soil stoichiometry. Therefore, the plants in coastal wetlands vary significantly at a small scale in response to the disturbance of artificial seawalls. The differences in soil and plants between the two habitats divided by the artificial seawalls provide a new insight for evaluating the artificial coastal projects. The only way to reduce the effects of seawalls on natural coastal wetland vegetation and ecosystem functions is to restore connectivity of tidal flow inside and outside the seawalls.

The soil quality index (SQI) is a comprehensive indicator that reflects the agricultural productivity of soil, as well as playing important roles in understanding microbial nutrient metabolism and carbon use efficiency (CUE). However, it is unclear how drip irrigation treatments in apple orchards affect the SQI, eco-enzyme stoichiometry, and soil microbial CUE. Thus, in the present study, we tested three different treatments in orchard plots: T1 (50-60 % field water capacity (theta f)), T2 (65-75 % theta f), and T3 (80-90 % theta f), as well as control with no drip irrigation (CK). The study focused on the effects of these treatments during two key stages: bud breaking and fruit maturity. During the bud breaking stage, we observed that water availability had a more pronounced influence on the SQI when soil moisture was limited. Specifically, in the 0-20 cm soil layer, the T2 treatment showed a significantly lower SQI value compared to T3, with a decrease of 31.89 %. On the other hand, there were no significant differences among all the irrigated treatments during the maturity stage. Both vector length and angle were significantly affected by water availability during the bud breaking stage, while only the vector angle was impacted during the maturity stage. The vector length and angle were both influenced by SQI (Mantel's test: p < 0.01). During the bud breaking stage, the CUE values in 0-20 cm layer under T1, T2, and T3 were 30.27 %, 21.79 %, and 85.47 % lower, respectively, compared with CK. By contrast, in the fruit maturity stage, CUE was 27.39 % higher under T1 compared with CK. SQI and CUE had a negative correlation in the bud breaking stage (p < 0.001, R-2 = 0.26), but a positive correlation in the fruit maturity stage (p < 0.001, R-2 = 0.51). Our findings suggest that the T3 treatment consistently yields the highest Soil Quality Index (SQI) across most soil layers during the bud breaking and maturity stages. Moreover, the T3 treatment effectively alleviates early spring drought in the Weibei region and encourages deep-root development, enabling fruit trees to absorb nutrients from deeper soil levels. Overall, these findings enhance our understanding of how the SQI and enzyme stoichiometry under drip irrigation affect phosphorus and carbon metabolism in soils, and they suggest that SQI should be considered a key factor that limits microbial metabolic restrictions and microbial CUE.

The current N and P fertilization practices for vegetable crops grown in organic soils are inaccurate and and may potentially damage the environment. New fertilization models are needed. Machine learning (ML) methods can combine numerous features to predict crop response to N and P fertilization. Our objective was to evaluate machine learning predictions for marketable yields, N and P offtakes, and the N/P ratio of vegetable crops. We assembled 157 multi-environmental fertilizer trials on lettuce (Lactuca sativa), celery (Apium graveolens), onion (Allium cepa), and potato (Solanum tuberosum) and documented 22 easy-to-collect soil, managerial, and meteorological features. The random forest models returned moderate to substantial strength (R2 = 0.73-0.80). Soil and managerial features were the most important. There was no response to added P and null to moderate response to added N in independent universality tests. The N and P offtakes were most impacted by P-related features, indicating N-P interactions. The N/P mass ratios of harvested products were generally lower than 10, suggesting P excess that would trigger plant N acquisition and possibly alter soil N and C cycles through microbial processes. Crop response prediction by ML models and ex post N/P ratio diagnosis and N and P offtakes proved to be useful tools to guide N and P management decisions in organic soils.

The chemical composition of meltwater-draining Himalayan glacierized basins reflects the dominance of carbonic acid in weathering of silicate and carbonate minerals, yet the role of sulfuric acid-mediated reactions in the mineral weathering and ionic release is still unclear. Here, we present a long-term study (1992-2018) of chemical weathering characteristics of a precipitation-dominated glacierized basin (Dokriani glacier) of central Himalaya. By using new and reprocessed datasets of major ions from the glacial/subglacial zones of the glacier, we suggest that two-thirds of the dissolved load of the meltwater derives from sulfuric acid-mediated weathering of minerals and rocks. We observed a clear control of carbonic acid-mediated reactions in the early ablation periods, while sulfuric acid-mediated reactions dominate in peak and late ablation periods. The slopes and intercepts in best-fit regressions of [*Ca2+ + *Mg2+ vs *SO42- and HCO3-] and [HCO3- vs *SO42-] in meltwater were following the stoichiometric parameters of sulfide oxidation coupled to carbonate dissolution reactions. The glaciers of the central and western Himalaya are in good agreement with the present estimates. We contend that the bedrock lithology has limited or second-order effects over the ionic release from Himalayan glaciers and surmise that these patterns are broadly applicable to the other orogenic systems of the world.

Plant nutrient uptake and productivity are driven by a multitude of factors that have been modified by human activities, like climate change and the activity of decomposers. However, interactive effects of climate change and key decomposer groups like earthworms have rarely been studied. In a field microcosm experiment, we investigated the effects of a mean future climate scenario with warming (+ 0.50 degrees C to + 0.62 degrees C) and altered precipitation (+ 10% in spring and autumn, - 20% in summer) and earthworms (anecic-two Lumbricus terrestris, endogeic-four Allolobophora chlorotica and both together within 10 cm diameter tubes) on plant biomass and stoichiometry in two land-use types (intensively used meadow and conventional farming). We found little evidence for earthworm effects on aboveground biomass. However, future climate increased above- (+40.9%) and belowground biomass (+44.7%) of grass communities, which was mainly driven by production of the dominant Festulolium species during non-summer drought periods, but decreased the aboveground biomass (- 36.9%) of winter wheat. Projected climate change and earthworms interactively affected the N content and C:N ratio of grasses. Earthworms enhanced the N content (+1.2%) thereby decreasing the C:N ratio (- 4.1%) in grasses, but only under ambient climate conditions. The future climate treatment generally decreased the N content of grasses (aboveground: - 1.1%, belowground: - 0.15%) and winter wheat (- 0.14%), resulting in an increase in C:N ratio of grasses (aboveground: + 4.2%, belowground: +6.3%) and wheat (+5.9%). Our results suggest that climate change diminishes the positive effects of earthworms on plant nutrient uptakes due to soil water deficit, especially during summer drought.

It is well-known that relative growth rate (RGR) is closely related to C:N:P stoichiometry at the whole-plant level, yet it remains a misgiving to determine whether the growth-rate hypothesis is consistent between plant organs. Here, we examined RGR, C, N, P concentrations and their ratios of N:C, P:C, and N:P for four marsh herbaceous species (two gramineous species, Deyeuxia angustifolia and Glyceria spiculosa; two sedge species, Carex pseudocuraica and Carex lasiocarpa) grown in an increasing water level gradient (-5, 0, +5, and +15 cm relative to the soil surface) in the Sanjiang Plain of Northeast China. The applicability of the growth-rate hypothesis to leaf, stem, root, and total biomass was subsequently tested. With the increase of flooding stress, RGR and root mass ratio decreased to a certain degree for all species, whereas the above-ground biomass allocation was increased. The variation of N was much greater than that of P; hence the change in N:P ratios was determined mainly by N concentration. RGR was positively correlated with N concentration, N:C, and N:P for stem and total biomass when the data were pooled for all species but was negatively correlated with those for leaf and root organs. Furthermore, the theoretical predictions regarding the relationship between RGR and nutrient ratios were not always the case for each of the marsh herbs. Therefore, our results indicated that the organ-specific and species-specific for vascular plants should be carefully considered when using the theoretical association of growth rate with C:N:P stoichiometry. (c) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Soil nutrient stoichiometry and its environmental controllers play vital roles in understanding soil-plant interaction and nutrient cycling under a changing environment, while they remain poorly understood in alpine grassland due to lack of systematic field investigations. We examined the patterns and controls of soil nutrients stoichiometry for the top 10 cm soils across the Tibetan ecosystems. Soil nutrient stoichiometry varied substantially among vegetation types. Alpine swamp meadow had larger topsoil C:N, C:P, N: P, and C:K ratios compared to the alpine meadow, alpine steppe, and alpine desert. In addition, the presence or absence of permafrost did not significantly impact soil nutrient stoichiometry in Tibetan grassland. Moreover, clay and silt contents explained approximately 32.5% of the total variation in soil C: N ratio. Climate, topography, soil properties, and vegetation combined to explain 10.3-13.2% for the stoichiometry of soil C: P, N: P, and C: K. Furthermore, soil C and N were weakly related to P and K in alpine grassland. These results indicated that the nutrient limitation in alpine ecosystem might shifts from N-limited to P-limited or K-limited due to the increase of N deposition and decrease of soil P and K contents under the changing climate conditions and weathering stages. Finally, we suggested that soil moisture and mud content could be good predictors of topsoil nutrient stoichiometry in Tibetan grassland. (C) 2017 Elsevier B.V. All rights reserved.