Phosphorus constrains global photosynthesis more than nitrogen does.

Global vegetation growth is thought to be limited by nitrogen (N) more than by other nutrients. Here we document a stronger phosphorus (P) limitation on global photosynthesis compared with N over the last four decades. On the basis of more than 80,000 field observations of foliar nutrients and a machine learning method, we generated a long-term global dataset of foliar N and P concentrations for the period 1980-2017.

Links Between Nitrogen Limitation and Saturation in Terrestrial Ecosystems.

Nitrogen (N) limitation and N saturation are two fundamental concepts in the field of terrestrial N biogeochemistry. Their ecological links, however, remain unclarified due to their distinct history of origin and the utilization by different research communities. Based on the non-linear responses of soil microbial growth, plant growth, and ecosystem N losses (e.

Global patterns of nutrient limitation in soil microorganisms.

The availability of nitrogen (N) and phosphorus (P) is essential for soil microbial activity and growth, yet global patterns of N and P limitation in soil microbial metabolism remain largely unknown. We modeled ecoenzyme stoichiometry data from 5,259 field observations of natural ecosystems to assess microbial N and P limitation in global surface soils. We found that microbial P limitation, which was especially strong at low latitudes, was more prevalent globally than microbial N limitation, which prevailed in cold environments.

Characteristics of leaf nutrient resorption efficiency in Tibetan alpine permafrost ecosystems.

Nutrient resorption is an important strategy for nutrient conservation, especially in permafrost ecosystems where plant growth is limited by nutrients. Based on the measurements mainly derived from tropical, subtropical and temperate regions, current projections suggest that resorption efficiency is higher for leaf nitrogen (N) than for phosphorus (P) in cold regions. However, these projections have not been fully validated due to the lack of observations in permafrost ecosystems.

Variations in the leaf economics spectrum, anatomical, ultrastructural, and stomatal traits of five tree species in the urban-rural air pollution environment.

Rapid urbanization has contributed to global increases in air pollution derived from urban areas. Unlike natural forests, urban forests are exposed to higher concentrations of airborne pollutants due to the strong urban-suburban-rural pollutant emission gradients. However, there remains a pressing lack of available information pertaining to the urban air pollution-related effects on the leaf economics spectrum, anatomical, ultrastructural, and stomatal traits of tree species along an urban-rural gradient.

Global engineering effects of soil invertebrates on ecosystem functions.

The biogenic structures produced by termites, ants and earthworms provide key functions across global ecosystems. However, little is known about the drivers of the soil engineering effects caused by these small but important invertebrates at the global scale. Here we show, on the basis of a meta-analysis of 12,975 observations from 1,047 studies on six continents, that all three taxa increase soil macronutrient content, soil respiration and soil microbial and plant biomass compared with reference soils.

Distinct seasonality of nutrients in twigs and leaves of temperate trees.

Seasonal variation of nutrient concentrations in different organs is an essential strategy for temperate trees to maintain growth and function. The seasonal variations and variability (i.e.

Assessing the seasonality of foliar nutrient concentrations in woody plants.

Seasonal variations in foliar nutrient concentrations are an important strategy of plants to adapt to different climates and availabilities of soil nutrients. Gaps in our knowledge, however, remain in both the seasonality of the concentrations of multiple nutrients in plant leaves and their spatial pattern on a large scale. We compiled data on foliar concentrations of nine essential nutrients (N, P, K, Ca, Mg, Fe, Mn, Zn, and Cu) in woody plants in China and evaluated the characteristics and latitudinal patterns of their seasonal variability (i.

Can ethylenediurea (EDU) alter the effects of ozone on the source-sink regulation of nitrogen uptake and remobilization during grain filling period in rice?

Increased surface ozone (O) pollution seriously threatens crop production, and ethylenediurea (EDU) can alleviate crop yield reduction caused by O. However, the reason for the decrease in grain nitrogen (N) accumulation caused by O and whether EDU serves as N fertilizer remain unclear. An experiment was conducted to investigate the impacts of factorial combinations of O enrichment (ambient air plus 60 ppb) and EDU (foliage spray with 450 ppm solutions) on N concentration, accumulation and remobilization in hybrid rice seedlings.

Distinct latitudinal patterns and drivers of topsoil nitrogen and phosphorus across urban forests in eastern China.

Nitrogen (N) and phosphorus (P) are the two most important macronutrients supporting forest growth. Unprecedented urbanization has created growing areas of urban forests that provide key ecosystem services for city dwellers. However, the large-scale patterns of soil N and P content remain poorly understood in urban forests.

Global distribution of surface soil organic carbon in urban greenspaces.

Urban greenspaces continue to grow with global urbanization. The global distribution and stock of soil organic carbon (SOC) in urban greenspaces remain largely undescribed and missing in global carbon (C) budgets. Here, we synthesize data of 420 observations from 257 cities in 52 countries to evaluate the global pattern of surface SOC density (0-20 cm depth) in urban greenspaces.

Attributing Atmospheric Phosphorus in the Himalayas: Biomass Burning vs Mineral Dust.

Atmospheric phosphorus is a vital nutrient for ecosystems whose sources and fate are still debated in the fragile Himalayan region, hindering our comprehension of its local ecological impact. This study provides novel insights into atmospheric phosphorus based on the study of total suspended particulate matter at the Qomolangma station. Contrary to the prevailing assumptions, we show that biomass burning (BB), not mineral dust, dominates total dissolved phosphorus (TDP, bioavailable) deposition in this arid region, especially during spring.

Rapid migration of Mongolian oak into the southern Asian boreal forest.

The migration of trees induced by climatic warming has been observed at many alpine treelines and boreal-tundra ecotones, but the migration of temperate trees into southern boreal forest remains less well documented. We conducted a field investigation across an ecotone of temperate and boreal forests in northern Greater Khingan Mountains of northeast China. Our analysis demonstrates that Mongolian oak (Quercus mongolica), an important temperate tree species, has migrated rapidly into southern boreal forest in synchrony with significant climatic warming over the past century.

A distinctive latitudinal trend of nitrogen isotope signature across urban forests in eastern China.

Rapid urbanization has greatly altered nitrogen (N) cycling from regional to global scales. Compared to natural forests, urban forests receive much more external N inputs with distinctive abundances of stable N isotope (δ N). However, the large-scale pattern of soil δ N and its imprint on plant δ N remain less well understood in urban forests.

Distinct urban-rural gradients of air NO and SO concentrations in response to emission reductions during 2015-2022 in Beijing, China.

Nitrogen dioxide (NO) and sulfur dioxide (SO) are two major air pollutants in urban environment. Emission reduction policies have thus been implemented to improve urban air quality, especially in the metropolises. However, it remains unclear whether the air concentrations of NO and SO in and around large cities follow a same spatial pattern and how their characteristics change over time in response to the emission reductions.

Reassessment of growth-climate relations indicates the potential for decline across Eurasian boreal larch forests.

Larch, a widely distributed tree in boreal Eurasia, is experiencing rapid warming across much of its distribution. A comprehensive assessment of growth on warming is needed to comprehend the potential impact of climate change. Most studies, relying on rigid calendar-based temperature series, have detected monotonic responses at the margins of boreal Eurasia, but not across the region.

Urban CO imprints on carbon isotope and growth of Chinese pine in the Beijing metropolitan region.

Rapid urbanization has occurred globally and resulted in increasing CO emissions from urban areas. Compared to natural forests, urban forests are subject to higher atmospheric CO concentrations in view of strong urban-periurban-rural gradients of CO emissions. However, relevant insights in the CO-associated urban imprints on the physiology and growth of regional forests remain lacking.

Hierarchical change-point regression models including random effects to estimate empirical critical loads for nitrogen using Bayesian Regression Models (brms) and JAGS.

The concept of critical loads is used in the framework of the Convention on Long-range Transboundary Air Pollution (UNECE) to define thresholds below which no damaging effects on habitats occur based on the latest scientific knowledge. Change-point regression models applied in a Bayesian framework are useful statistical tools to estimate critical empirical loads. While hierarchical study designs are common in ecological research, previous methods to estimate critical loads using change-point regression did not allow to analyse data collected under such a design.

High-level nitrogen additions accelerate soil respiration reduction over time in a boreal forest.

Increased nitrogen (N) inputs are widely recognised to reduce soil respiration (Rs), but how N deposition affects the temporal dynamics of Rs remains unclear. Using a decade-long fertilisation experiment in a boreal larch forest (Larix gmelini) in northeast China, we found that the effects of N additions on Rs showed a temporal shift from a positive effect in the short-term (increased by 8% on average in the first year) to a negative effect over the longer term (decreased by 21% on average in the 11th year). The rates of decrease in Rs for the higher N levels were almost twice as high as those of the low N level.

Strategic roadmap to assess forest vulnerability under air pollution and climate change.

Although it is an integral part of global change, most of the research addressing the effects of climate change on forests have overlooked the role of environmental pollution. Similarly, most studies investigating the effects of air pollutants on forests have generally neglected the impacts of climate change. We review the current knowledge on combined air pollution and climate change effects on global forest ecosystems and identify several key research priorities as a roadmap for the future.

Retention of deposited ammonium and nitrate and its impact on the global forest carbon sink.

The impacts of enhanced nitrogen (N) deposition on the global forest carbon (C) sink and other ecosystem services may depend on whether N is deposited in reduced (mainly as ammonium) or oxidized forms (mainly as nitrate) and the subsequent fate of each. However, the fates of the two key reactive N forms and their contributions to forest C sinks are unclear. Here, we analyze results from 13 ecosystem-scale paired N-labelling experiments in temperate, subtropical, and tropical forests.

Plant sizes and shapes above and belowground and their interactions with climate.

Although the above and belowground sizes and shapes of plants strongly influence plant competition, community structure, and plant-environment interactions, plant sizes and shapes remain poorly characterized across climate regimes. We investigated relationships among shoot and root system size and climate. We assembled and analyzed, to our knowledge, the largest global database describing the maximum rooting depth, lateral spread, and shoot size of terrestrial plants - more than doubling the Root Systems of Individual Plants database to 5647 observations.

Nonlinear responses of ecosystem carbon fluxes to nitrogen deposition in an old-growth boreal forest.

Nitrogen (N) deposition is known to increase carbon (C) sequestration in N-limited boreal forests. However, the long-term effects of N deposition on ecosystem carbon fluxes have been rarely investigated in old-growth boreal forests. Here we show that decade-long experimental N additions significantly stimulated net primary production (NPP) but the effect decreased with increasing N loads.

The diurnal cycle of summer tropospheric ozone concentrations across Chinese cities: Spatial patterns and main drivers.

China is experiencing severe tropospheric ozone pollution, especially during the summer period in cities. Previous studies have assessed the role of meteorological conditions and anthropogenic precursors in shaping the diurnal variation of ozone concentration in some Chinese cities or the spatial patterns of daytime ozone concentration, but less is known about the spatial variation and main regulators of the diurnal cycle of summer ozone concentrations in Chinese cities. Using monitoring data from 367 cities, we analyzed the spatial patterns and main regulators of daytime maximum, nighttime minimum and diurnal difference of summer (June-August) ozone concentration during 2015-2019.

Spatially divergent trends of nitrogen versus phosphorus limitation across European forests.

Nitrogen (N) and phosphorus (P) are essential nutrients that widely limit plant growth in global terrestrial ecosystems. Rising atmospheric CO concentration generally stimulates terrestrial net primary productivity and consequently may cause or aggravate N and P limitation due to a dilution effect, but the spatial variation of temporal trends in N versus P limitation and its key regulating factors is poorly understood. Using the leaf N:P ratio of 15 dominant tree species as an indicator, we analysed the spatial variation of plot-level shift towards N or P limitation across 163 European forest plots during 1995-2017.