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More efficient use of soil resources, such as nitrogen (N) and phosphorus (P), can improve plant community resistance and resilience against drought in arid and semi-arid lands. Intercropping of legume and non-legumes can be an effective practice for enhancing P mineralization uptake, and plant nutrient status. However, it remains unclear how intercropping systems using desert plant species impact soil-plant P fractions and how they affect N and water uptake capacity. Alhagi sparsifolia (a legume) and Karelinia caspia (a non-legume) are dominant plant species in the Taklamakan Desert in Xinjiang Province, China. However, there is a lack of knowledge of whether these species, when intercropped, can trigger synergistic processes and mechanisms that drive more efficient use of soil resources. Thus, in a field experiment over two years, we investigated the impact of monoculture and intercropping of these plant species on soil-plant P fractions and soil-plant nutrients. Both plant species' foliar nutrient (N, P, and K) concentrations were higher under monoculture than intercropping (except K in K. caspia). Nucleic acid P was higher in the monoculture plots of A. sparsifolia, consistent with higher soil labile P, while metabolic P was higher in monoculture K. caspia, associated with higher soil moderately labile Pi. However, both species had a higher residual P percentage in the intercropping system. Soils from monoculture and intercropped plots contained similar microbial biomass carbon (MBC), but lower microbial biomass N:microbial biomass phosphorus (MBN:MBP) ratio associated with reduced N-acetylglucosaminidase (NAG) activity in the intercropped soils. This, together with the high MBC:MBN ratio in intercropping and the lack of apparent general effects of intercropping on MBC:MBP, strongly suggest that intercropping improved microbe N- but not P-use efficiency. Interestingly, while EC and SWC were higher in the soil of the K. caspia monoculture plots, EC was significantly lower in the intercropped plots. Plants obtained better foliar nutrition and soil P mineralization in monocultures than in intercropping systems. The possible positive implications of intercropping for reducing soil salinization and improving soil water uptake and microbial N-use efficiency could have advantages in the long term and its utilization should be explored further in future studies. [ABSTRACT FROM AUTHOR]

Drought is one of the major environmental stresses altering forest productivity. However, nutrient availability can modulate drought resistance. Phoebe zhennan (gold Phoebe) is a high‐quality timber‐producing but threatened tree species in China, facing serious anthropogenic disturbances and abiotic constraints that restrict its growth and development. However, little attention has been given to designing adaptive strategies for its management by evaluating the possible role of major nutrients, particularly nitrogen (N), on its morphological and physio‐biochemical responses under water stress. To evaluate these responses, a complete randomized design was followed to investigate the effects of two irrigation levels (well‐watered and drought‐stressed conditions) and N fertilization treatments (with and without N). Drought stress significantly affected the growth of seedlings, as indicated by impaired photosynthesis, pigment degradation, disrupted N metabolism, over‐production of reactive oxygen species and enhanced lipid peroxidation. Nitrogen supplementation under drought stress had remarkable positive effects on the growth through physio‐biochemical adjustments as shown by higher level of nitrogenous compounds and up‐regulation of N‐associated metabolic enzymes activities which might be due to N‐mediated improved leaf relative water contents and photosynthetic efficiency. In addition, N application reduced oxidative stress and membrane damage, and maintained a high accumulation of osmolytes. However, in well‐watered seedlings N fertilization significantly improved root biomass and net CO2 assimilation rate suggesting high N‐use efficiency of the seedlings. These findings reveal that drought significantly affects the growth of P. zhennan, while N fertilization plays a crucial role in alleviating water stress damage by improving its drought tolerance potential at low metabolic costs. Therefore, N fertilization could be considered as an effective strategy for the conservation and management of P. zhennan in the face of future climate change. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alhagi sparsifolia offers a variety of socio-ecological services in arid lands. • Unsustainable activities for agricultural purposes may threaten nutrient cycling. • Long-term burning and cutting affect the foliar nutrition of A. sparsifolia. • Long-term overexploitation can impact the nutritional quality of A. sparsifolia. • Sustainable management of A. sparsifolia is crucial for ecological restoration. Arid ecosystems are characterized by low availability and mobility of soil nutrients and slow geochemical cycles. Management of native vegetation in such ecosystems for fuel, livestock grazing, and other agricultural activities (burning and cutting) may threaten semi-natural communities due to the changes in nutrient cycles and soil fertility. Alhagi sparsifolia is a dominant perennial legume in the Taklamakan Desert of northwestern China and has been used as fodder for livestock and plays a crucial ecological role in stabilizing dunes in the oasis-desert ecotone. We evaluated the effects of long-term (12 years) burning and cutting of plant biomass on the mineral nutrition of A. sparsifolia and associated soils at two depths (0–50 and 50–100 cm) in the field conditions following the block design experiment. We found that burning effects tended to be restricted to the topsoil (0–50 cm), and the concentration of many micro-and macronutrients was increased. Burning was associated with a decrease in plant nitrogen (N) and phosphorus (P) concentration, whereas concentrations of other micro-and macronutrients increased; overall, burning reduced foliar stocks of N, P, and potassium (K). Annual cutting elicited smaller increases in soil mineral (total sulfur, total P, calcium, magnesium, and available P and K) concentrations than burning, and soil enzymatic activities increased. There were contrasting response patterns of leaf N and P concentration and macro-and micronutrients between the two management approaches. Burning and cutting reduced leaf N and P concentrations, while changes in root and shoot N and P concentrations depended on treatments. Thus, burning and cutting of A. sparsifolia impact organ nutrient stoichiometry (increased losses of macronutrients from arid plant-soil ecosystems) and nutritional quality (for feeding livestock), particularly due to predicted rises in extreme climatic events under climate change that are expected to increase risks of soil erosion, however, impacts on native trophic webs remain unclear. [ABSTRACT FROM AUTHOR]

Vegetation restoration in deserts is challenging due to these ecosystems' inherent fragility and harsh environmental conditions. One approach for active restoration involves planting native species, which can accelerate the recovery of ecosystem functions. To ensure the effectiveness of this process, carefully selecting species for planting is crucial. Generally, it is expected that a more diverse mix of species in the plantation will lead to the recovery of a greater number of ecosystem functions, especially when the selected species have complementary niche traits that facilitate maximum cooperation and minimize competition among them. In this study, we evaluated the planting of two native species from the hyper-desert of Taklamakan, China, which exhibit marked morpho-physiological differences: a phreatophytic legume (Alhagi sparsifolia) and a halophytic non-legume (Karelinia caspia). These species were grown in both monoculture and intercrop communities. Monoculture of the legume resulted in the highest biomass accumulation. Intercropping improved several ecosystem functions in the 50 cm-upper soil, particularly those related to phosphorus (P), carbon (C), and sulfur (S) concentrations, as well as soil enzyme activities. However, it also increased soil sodium (Na + ) concentration and pH. Halophyte monocultures enhanced ecological functions associated with nitrogen concentrations in the upper soil and with P, S, C, and cation concentrations (K + , Ca 2+ , Mg 2+ , Cu 2+ , Fe 2+ , Zn 2+ , Co 2+ , Ni 2+ ), along with enzyme activities in the deep soil. It also maximized Na + accumulation in plant biomass. In summary, we recommend legume monoculture when the primary goal is to optimize biomass accumulation. Conversely, halophyte monoculture is advisable when the objective is to extract sodium from the soil or enhance ecosystem functions in the deep soil. Intercropping the two species is recommended to maximize the ecosystem functions of the upper soil, provided there is no salinization risk. When planning restoration efforts in desert regions, it is essential to understand the impact of each species on ecosystem function and how complementary species behave when intercropped. However, these interactions are likely species- and system-specific, highlighting the need for more work to optimize solutions for different arid ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)