Foliar Phosphorus Concentrations Research Articles

Effects of soil and phylogeny on sulfur and phosphorus concentrations in wild plants on volcanic and non-volcanic soils in Japan

ABSTRACT Andosols are soils characterized by relatively high sulfur concentrations, but also by their low phosphorus availability for crops and vegetables. We assessed the effect of soil type on the concentrations of sulfur and phosphorus in plants using handheld X-ray fluorescence (XRF) analysis on herbarium specimens collected from Andosols and non-volcanic soils in Japan. The sulfur concentrations in plants from Andosols were higher than plants from non-volcanic soils, but there was no significant difference between their foliar phosphorus concentrations. Only three specimens out of 1203 herbarium specimens were below the sulfur concentration (1000 mg kg−1) needed for adequate growth of crops, but about half of specimens were below that for phosphorus (2000 mg kg−1). The sulfur concentrations were high in herbaceous plants, especially in plants from the Brassicaceae and Liliaceae families. Overall, the results show that the sulfur concentrations in wild plants from Japan were higher in Andosols, with a low risk for sulfur deficiency. In contrast, the effect of soil type on the phosphorus concentrations in plants was small, and this may be explained because most wild plants grow under phosphorus-limiting conditions. Finally, the analysis reveals a strong correlation between sulfur and phosphorus concentrations in plants, suggesting the existence of a mechanism that controls the sulfur and phosphorus concentration ratios.

Foliar phosphorus concentration modulates the defensive mutualism of an endophytic fungus in a perennial host grass

Abstract Grasses hosting Epichloë endophytes are protected against herbivores due to the production of various fungal alkaloids. Previous research has found that high foliar phosphorus concentrations reduce the level of the alkaloid ergovaline, thereby reducing the endophyte‐mediated herbivore resistance. Yet, the impact of phosphorus on ergovaline biosynthesis versus its influence on endophyte growth and synthesis of other fungal alkaloids remains unresolved. Our objective was to elucidate these relationships. We grew endophyte‐symbiotic and non‐symbiotic Festuca arundinacea plants and fertilised them with different doses of phosphorus. Later, half of the plants from each treatment were challenged with larvae of the generalist chewing insect Spodoptera frugiperda. We assessed the relationships between foliar phosphorus levels, fungal mycelium and alkaloid concentrations, as well as their impacts on larvae performance, herbivore‐caused damage and plant biomass. Endophyte mycelial biomass in plant tissue was found to be independent of foliar phosphorus concentration. The alkaloids lolines and peramine showed a linear relationship with mycelial biomass but no correlation with foliar phosphorus. Surprisingly, high ergovaline concentrations were positively associated with an interaction between endophyte mycelial biomass and foliar phosphorus concentration. Although herbivory increased loline concentration, only high concentrations of ergovaline and peramine were related to reduced S. frugiperda larvae weight gain. However, endophyte presence did not reduce herbivory damage on plants. Contrary to expectation, we did not find a negative but a positive association between concentrations of foliar phosphorus and ergovaline alkaloid, through its interaction with endophyte mycelial biomass. Alternatively, our findings suggest that phosphorus plays a crucial role in modulating the Epichloë‐mediated defensive mutualism, primarily through its effects on ergovaline rather than on endophyte concentration or production of other alkaloids. Read the free Plain Language Summary for this article on the Journal blog.

Seasonal monitoring of biochemical variables in natural rangelands using Sentinel-1 and Sentinel-2 data

ABSTRACT Rangelands are natural ecosystems that serve as essential sources of forage for domesticated livestock and wildlife. Therefore, accurately mapping nutrient levels in rangelands is crucial for sustainable development and effective management of grazing animals. Remote sensing tools offer a reliable means to explore nutrient concentrations across large spatial areas. This study aimed to estimate and map seasonal foliar concentrations of nitrogen (N), phosphorus, and neutral detergent fibre (NDF) in mesic tropical rangelands of Limpopo using Sentinel-1, Sentinel-2, and the integration of S1 and S2 data. Fieldwork was conducted to collect samples for seasonal foliar nutrients (N, P, and NDF) during early-summer (November-January 2020), winter (July-August 2021), and late-summer (February-March 2022). Various conventional and red-edge-based vegetation indices were computed. The results demonstrate that integration data from S1 and S2 can effectively estimate and predict foliar concentrations of N, P, and NDF in mesic rangelands throughout the seasons, achieving R2 values of 0.76, 0.78, and 0.71, with corresponding RMSE values of 0.13, 0.04, and 2.52. Notably, red-edge variables emerged as the most significant parameters for predicting seasonal N, P, and NDF concentrations. Additionally, factors such as season and slope significantly influenced the distribution and occurrence of these foliage nutrients, with higher foliage production observed during late-summer and on steeper slopes. The study concludes that the integration of S1 and S2 data can effectively monitor the seasonal dynamics of biochemical parameters. This finding holds significant implications for policymakers and rangeland users, offering a comprehensive understanding of the intricate variations within rangeland ecosystems. Further research could expand on these findings by applying the knowledge to various datasets, exploring different rangelands, and examining additional ecological factors such as slope altitude to detect foliar fibre biochemicals. Finally, the applications of this research extend beyond individual properties, providing practical tools for sustainable rangeland management and informed decision-making in resource utilization and conservation.

Leaf traits of Central-European beech (Fagus sylvatica) and oaks (Quercus petraea/robur): Effects of severe drought and long-term dynamics

In 2018—2020, Central-European forests suffered from extremely hot and dry summers. We used data from long-term forest monitoring of six stands of European beech (Fagus sylvatica) and two stands of oak (Quercus petraea/Q. robur) growing on different geological substrates in the climatically uniform state of Saarland (south-western Germany) for analyzing leaf traits of the period 2004—2021. We aimed at detecting overall effects of the drought on foliar morphology, nutrient concentrations, and injury, and long-term alterations in these traits. Across sites, drought resulted in a decrease in leaf size and specific leaf area (SLA) and increased fruiting in the beech and a decrease in the foliar nitrogen (N) concentrations in both tree genera. During drought, foliar calcium and manganese concentrations were lower and potassium (K) concentrations higher across the beech stands, whereas in the oak stands, drought led to a reduction in the foliar phosphorus (P) and magnesium (Mg) concentrations. High rates of anthropogenic N deposition during recent decades have resulted in high foliar N concentrations and low to deficient concentrations of P and, in the beech, of Mg. However, a significant (negative) long-term trend in leaf traits across the study sites was only found for the K concentration and necroses of the beech leaves. Foliar N correlated positively with SLA in the beech and with leaf size in the oak but was not related to herbivory. Chlorosis was the only leaf trait that, in the beech, correlated (negatively) with the climatic water balance. We conclude that even severe drought during three consecutive years does not seem to critically affect the nutrient supply to the two most important deciduous forest tree genera of Central Europe. In the beech, a decrease in leaf size and SLA might be used as an early indication of severe drought stress effects in regular monitoring programs.

The cumulative impacts of droughts and N deposition on Norway spruce (Picea abies) in Switzerland based on 37 years of forest monitoring

Norway spruce is one of the most important tree species in Central Europe, however, it is facing major problems with recent droughts. In this study we present 37 years (1985–2022) of long-term forest observation data on 82 different forest sites across Switzerland including 134′348 tree observations. The sites consists of managed spruce or mixed forest stands with beech (Fagus sylvatica) and comprise large gradients in altitude (290–1870 m), precipitation (570–2448 mm a−1), temperature (3.6–10.9 °C) or total nitrogen deposition (8.5–81.2 kg N ha−1 a−1).Long-term tree mortality has increased more than fivefold due to the multiple drought years 2019, 2020 and 2022, which is more than double the increase following the 2003 drought. We used a Bayesian multilevel model including three years of lagged drought indicator to predict spruce mortality. Besides stand age, the most important factors were drought and N deposition. Especially under drought conditions spruce mortality was increased on sites with high N deposition. Moreover, N deposition increased the imbalance of foliar phosphorus concentrations, with negative impacts on tree mortality. Mortality was increased by a factor of 1.8 in spruce compared to mixed beech and spruce stands. Stands with high mortality rates showed previously an increased proportion of trees with damaged crowns, especially after the droughts of 2003 and 2018.Taken together, we found evidences of an increase in spruce mortality droughts amplified under high N depositions. The perennial drought of 2018–2020 resulted in a cumulative spruce mortality of 12.1 % (564 dead trees in 82 sites) in only three years. With a Bayesian change-point regression framework we estimated a critical empirical load for nitrogen of 10.9 ± 4.2 kg N ha−1 a−1, which is in line with current thresholds, above which future plantings of spruce in Switzerland may not be a sustainable option due to the observed interaction between drought and nitrogen deposition.

Limits to reproduction and seed size-number trade-offs that shape forest dominance and future recovery

The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four major findings emerged. First, seed production is not constrained by a strict trade-off between seed size and numbers. Instead, seed numbers vary over ten orders of magnitude, with species that invest in large seeds producing more seeds than expected from the 1:1 trade-off. Second, gymnosperms have lower seed production than angiosperms, potentially due to their extra investments in protective woody cones. Third, nutrient-demanding species, indicated by high foliar phosphorus concentrations, have low seed production. Finally, sensitivity of individual species to soil fertility varies widely, limiting the response of community seed production to fertility gradients. In combination, these findings can inform models of forest response that need to incorporate reproductive potential.

Climate change influences foliar nutrition and metabolism of red maple (Acer rubrum) trees in a northern hardwood forest

AbstractMean annual air temperatures are projected to increase, while the winter snowpack is expected to shrink in depth and duration for many mid‐ and high‐latitude temperate forest ecosystems over the next several decades. Together, these changes will lead to warmer growing season soil temperatures and an increased frequency of soil freeze–thaw cycles (FTCs) in winter. We took advantage of the Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire, USA, to determine how these changes in soil temperature affect foliar nitrogen (N) and carbon metabolism of red maple (Acer rubrum) trees in 2015 and 2017. Earlier work from this study revealed a similar increase in foliar N concentrations with growing season soil warming, with or without the occurrence of soil FTCs in winter. However, these changes in soil warming could differentially affect the availability of cellular nutrients, concentrations of primary and secondary metabolites, and the rates of photosynthesis that are all responsive to climate change. We found that foliar concentrations of phosphorus (P), potassium (K), N, spermine (a polyamine), amino acids (alanine, histidine, and phenylalanine), chlorophyll, carotenoids, sucrose, and rates of photosynthesis increased with growing season soil warming. Despite similar concentrations of foliar N with soil warming with and without soil FTCs in winter, winter soil FTCs affected other foliar metabolic responses. The combination of growing season soil warming and winter soil FTCs led to increased concentrations of two polyamines (putrescine and spermine) and amino acids (alanine, proline, aspartic acid, γ‐aminobutyric acid, valine, leucine, and isoleucine). Treatment‐specific metabolic changes indicated that while responses to growing season warming were more connected to their role as growth modulators, soil warming + FTC treatment‐related effects revealed their dual role in growth and stress tolerance. Together, the results of this study demonstrate that growing season soil warming has multiple positive effects on foliar N and cellular metabolism in trees and that some of these foliar responses are further modified by the addition of stress from winter soil FTCs.

Nitrogen use efficiency of terrestrial plants in China: geographic patterns, evolution, and determinants

BackgroundPlant nitrogen use efficiency (NUE) is an important ecological indicator that reflects the capacity of a plant to transform nitrogen into production, which is essential for further elucidating plant growth and terrestrial ecosystem productivity. Although there are a growing number of studies that address NUE changes at local scales, the variations of NUE over large spatial scales remain unclear. In this study, we analyzed the geographic patterns of NUE and explored its phylogenic and environmental drivers across 1452 species at 1102 sites in China.ResultsNUE tended to decrease with latitude (r = − 0.56), whereas it increased with longitude (r = 0.54), and varied widely in different ecosystems and plant life forms. Furthermore, NUE was negatively correlated with plant foliar phosphorus concentration (r = − 0.53), soil pH (r = − 0.10), soil total phosphorus (r = − 0.13) and available phosphorus (r = − 0.05), but positively with the mean annual temperature (r = 0.32), annual precipitation (r = 0.27), and aridity index (r = 0.26). NUE was significantly altered with phylogeny and evolved toward a lower value (r = − 0.28), which may have been due to increasing nitrogen deposition and fixation in biogeochemical evolution. Overall, the combination of foliar phosphorus concentration, phylogeny, climate, and soil properties accounted for 52.7% of the total variations of NUE. In particular, foliar phosphorus concentration was the most important factor, whereas plant evolutionary history was second in contributing to NUE variations.ConclusionsOur study emphasizes the pivotal role of plant stoichiometry and phylogeny in nitrogen cycling and suggests incorporating them into earth system models to better understanding plant growth and nitrogen cycling in the context of environmental changes.

Global maps and factors driving forest foliar elemental composition: the importance of evolutionary history.

Consistent information on the current elemental composition of vegetation at global scale and the variables that determine it is lacking. To fill this gap, we gathered a total of 30 912 georeferenced records on woody plants foliar concentrations of nitrogen (N), phosphorus (P) and potassium (K) from published databases, and produced global maps of foliar N, P and K concentrations for woody plants using neural networks at a resolution of 1 km2 . We used data for climate, atmospheric deposition, soil and morphoclimatic groups to train the neural networks. Foliar N, P and K do not follow clear global latitudinal patterns but are consistent with the hypothesis of soil substrate age. We additionally built generalized linear mixed models to investigate the evolutionary history effect together with the effects of environmental effects. In this comparison, evolutionary history effects explained most of the variability in all cases (mostly > 60%). These results emphasize the determinant role of evolutionary history in foliar elemental composition, which should be incorporated in upcoming dynamic global vegetation models.

Does phosphorus influence performance of a native hemiparasite and its impact on a native legume?

Phosphorus (P) is an essential plant nutrient and can become limiting in terrestrial ecosystems where parasitic plant:host associations occur. Yet little is known on how P availability influences parasite performance and its impact on hosts. We investigated the performance of the Australian native stem hemiparasite Cassytha pubescens and its impact on the native leguminous shrub Acacia paradoxa in high or low P conditions in a glasshouse experiment. Infected plants had significantly lower total, shoot, root and nodule biomass and shoot:root ratio than uninfected plants, regardless of P supply. The significant negative effect of infection on arbuscular mycorrhizal colonisation of host roots was more severe in the high P treatment. Infection significantly decreased predawn quantum yield of A. paradoxa in low P but not high P conditions. This finding may be due to the parasite-induced significant enrichment of aluminium in host foliage in low P but not high P treatments. A. paradoxa had significantly lower foliar phosphorus concentration [P] and nitrogen concentration in low P than high P conditions. Parasite biomass and photosynthetic performance were unaffected by P, whereas C. pubescens had significantly lower stem [P] in the low P than high P treatment. Parasite carbon isotope composition was significantly higher than that of the host, especially in low P conditions. Our results show that: (a) native parasite growth and its negative impact on growth of this native shrub was unaffected by P supply and (b) soil P conditions may have no influence on stem hemiparasite:host associations in nature.

Phosphorus Leaching From Naturally Structured Forest Soils Is More Affected by Soil Properties Than by Drying and Rewetting

Foliar phosphorus (P) concentrations in beech trees are decreasing in Europe, potentially leading to reductions in the trees’ growth and vitality. In the course of climate change, drying and rewetting (DRW) cycles in forest soils are expected to intensify. As a consequence, P leakage from the root zone may increase due to temporarily enhanced organic matter mineralization. We addressed the questions whether sites with different soil properties, including P pools, differ in their susceptibility to DRW-induced P leaching, and whether this is affected by the DRW intensity. A greenhouse experiment was conducted on naturally structured soil columns with beech saplings from three sites representing a gradient of soil P availability. Four DRW cycles were conducted by air-drying and irrigating the soils over 4 hours (fast rewetting) or 48 hours (slow rewetting). Leachates below the soil columns were analyzed for total P, and molybdate reactive P (considered as inorganic P). The difference was considered to represent organically bound P. Boosted regression trees were used to examine the effects of DRW and soil characteristics on P leaching. Contrary to a first hypothesis, that P leaching increases upon rewetting with the intensity of the preceding desiccation phase, intense soil drying (to pF 3.5 to 4.5) did not generally increase P leakage compared to moderate drying (to pF 2 to 3). However, we observed increased inorganic P concentrations and decreased organic P concentrations in leachates after drying to matric potentials above pF 4. Also against our expectations, fast rewetting did not lead to higher leakage of P than slow rewetting. However, the results confirmed our third hypothesis that the site poorest in P, where P recycling is mainly limited to the humus layer and the uppermost mineral soil, lost considerably more P during DRW than the other two sites. The results of our experiment with naturally structured soils imply that intensified drying and rewetting cycles, as predicted by climate-change scenarios, may not per se lead to increased P leaching from forest soils. Soil properties such as soil organic carbon content and texture appear to be more important predictors of P losses.

Effect of Salinization by NaCl on the Growth of African Palm (Elaeis guineensis Jacq)

It is necessary to know the effect of excessive salinity in the soil on the growth of the African palm crop. The objective of the work was to evaluate the effect of salinity caused by NaCl on the growth and absorption of nutrients in the oil palm crop in early growth stage. The research was carried out in the laboratories of the University of Cordoba, where the 16 kg experimental units were made up of a mixture of alluvium and rice husk in a ratio of 4: 1. A complete randomized design was used with six treatments and a control (0.0, 0.5, 1.0, 1.5, 2.5, 3.6, and 6.1 cmolc kg-1 Na) and four repetitions. The data were statistically analyzed by analysis of variance and regression. The results report that the salinity in the soil that originates with the application of 2.5 cmolc kg-1 of Na produces in the soil an electrical conductivity (EC) of 1.96 dS m-1. Consequently, a drastic reduction in the quantified biomass of dry mass of stem, leaf, roots, rachis and leaf area originates, and the models that express this trend were adjusted to decreasing linear regressions with their highly significant parameters. Salinity interferes with the absorption of nutritional elements, such as N, K+ and Mg2+, and foliar nitrogen is the nutrient with the highest sensitivity to variations in EC in the soil. Foliar phosphorus (P) and calcium (Ca) concentrations were not affected by salinity levels.

Tripartite symbioses regulate plant–soil feedback in alder

Abstract Plant–soil feedbacks regulate plant productivity and diversity, but potential mechanisms underpinning such feedbacks, such as the allocation of recent plant assimilate, remain largely untested especially for plants forming tripartite symbioses. We tested how soils from under alder Alnus glutinosa and beneath other species of the same and different families affected alder growth and nutrition, and colonization of roots by nitrogen‐fixing Frankia bacteria and ectomycorrhizal fungi. We also measured how the soil environment affected carbon capture and allocation by pulse labelling seedlings with 13CO2. We then tested for linkages between foliar nutrient stoichiometry and carbon capture and allocation and soil origin using statistical modelling approaches. Performance of alder and nitrogen nutrition were best on home and birch Betula pendula soils (both Betulaceae), whereas performance on Douglas fir Pseudotsuga menziesii (Pinaceae) soil was poor. Plants growing in P. menziesii soil were virtually devoid of Frankia and ectomycorrhizas, and the natural abundance 15N signatures of leaves were more enriched indicating distinct nitrogen acquisition pathways. Seedlings in these soils also had smaller 13C fixation and root allocation rates, leading to smaller 13C respiration rates by microbes. Statistical models showed that the best predictors of foliar N concentration were 13C allocation rates to fine roots and net CO2 exchange from the mesocosms. The best predictors for foliar phosphorus concentration were net CO2 exchange from the mesocosms and soil origin; seedlings in home soils tended to have greater foliar phosphorus compared to birch soils while seedlings from Douglas fir soils were no different from the other treatments. Foliar phosphorus concentration was not correlated with plant available or total soil phosphorus for any of the soils. Home soils also resulted in distinct ectomycorrhizal communities on seedlings roots, which could be responsible for greater foliar phosphorus concentration. Our findings show how the association of alder with nitrogen‐fixing Frankia relieved nitrogen limitation in the seedling triggering a performance feedback loop. We propose that relief of nitrogen limitation likely increases plant phosphorus demand, which may promote the formation of ectomycorrhizas in nutrient‐deficient soils. The formation of tripartite symbioses therefore generates positive plant–soil feedbacks, which enables plants to acquire mineral nutrients otherwise inaccessible in trade for carbon. A free Plain Language Summary can be found within the Supporting Information of this article.

Nutrient resorption and stoichiometric responses of poplar (Populus deltoids) plantations to N addition in a coastal region of eastern China

Abstract Aims Leaf nutrient resorption is sensitive to changes in soil nutrients. However, the effects of N deposition on nutrient resorption efficiency (NuRE) in plant macro-nutrients remain unclear. Poplar (Populus deltoids) is one of the most extensively cultivated hardwood species worldwide. We explored general patterns and dominant drivers of NuRE and stoichiometry of poplar plantations in response to N addition. Methods We conducted a 4-year N-addition experiment to explore NuRE and stoichiometric responses to N addition in two poplar (P. deltoids) plantations (8- and 12-year-old stands) in a coastal region of eastern China. We measured soil and foliar (green and senesced leaves) concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) for a series of N addition treatments including N0 (0 kg N ha−1 yr−1), N1 (50 kg N ha−1 yr−1), N2 (100 kg N ha−1 yr−1), N3 (150 kg N ha−1 yr−1) and N4 (300 kg N ha−1 yr−1). Important Findings Consistent for (both) 8- and 12-year-old stands, N addition did not affect the NuRE and stoichiometry (with the exception of CaRE and CaRE:MgRE ratio). N resorption efficiency–P resorption efficiency (NRE–PRE) scaling slopes were consistently less than 1.0 under N addition. These results suggest that NRE generally decouples from PRE within each N treatment. Moreover, these results point to robust control of green leaf nutritional status on nutrient resorption processes as indicated by the positive relationships between NuRE and green leaf nutrient concentrations. Our findings provided a direct evidence that growth in 12-year-old poplar plantations was N-limited in the coastal region of eastern China.

Soybean growth and foliar phosphorus concentration mediated by arbuscular mycorrhizal fungi from soils under different no-till cropping systems

Soil use and management modify mycorrhizal interactions, but how these changes affect the growth and nutrition of crops under different contexts has been poorly studied. The objective of this study was to evaluate the effects of arbuscular mycorrhizal fungal (AMF) spore communities belonging to two no-till cropping systems (soybean monoculture and soybean-maize rotation), and uncultivated grasslands replicated at four locations along a regional geographic gradient on soybean mycorrhizal colonization and performance. At a regional scale, AMF spore richness was higher in uncultivated grasslands, intermediate in crop rotations, and lower in monocultures. Arbuscular mycorrhizal colonization in soybean roots was also higher in uncultivated soils but did not differ between no-tillage systems. Soybean growth was positively affected by AMF from uncultivated grasslands in comparison to control without AMF. Instead, there were no significant effects of AMF from no-till cropping systems. Foliar P concentration was lower in monocultures irrespective of AMF. At the local scale, patterns were highly variable and differed between locations. These results highlight the importance of scales for management decisions in agriculture and add further support for the context-dependent nature of mycorrhizal interactions.

Harsh environmental regimes increase the functional significance of intraspecific variation in plant communities

Abstract The relative importance of intraspecific trait variation (rITV) for functional diversity (FD) in plant communities is increasingly apparent, but the influence of abiotic factors on the balance between intraspecific and interspecific effects in contrasting environments is uncertain. Drawing on a novel conceptual and analytic framework, we quantified rITV as the ratio of FD associated with between‐population ITV (Intra_FD) and the interspecific variation (Inter_FD) due to species turnover across sites. We predicted that rITV would increase with environmental harshness as a result of decreasing interspecific variation and concomitant increases in between‐population ITV. We empirically tested this prediction in a comparison of rITV for five traits (mature plant height, SLA, leaf dry matter content and the foliar concentrations of nitrogen and phosphorus (P)) characterizing species in Tibetan alpine meadow communities from contrasting environmental regimes. We found that across sites: (a) rITV for all five traits increased with environmental harshness not only through decreasing Inter_FD but also through increasing Intra_FD; (b) increases in rITV were mostly attributable to declines in soil resources, especially soil P, with lower soil P significantly associated with lower Inter_FD but higher Intra_FD for most traits; and (c) although neither Intra_FD nor Inter_FD was significantly impacted by species richness for any traits, a higher rITV for SLA was significantly associated with low species richness. Taken together, these results support our hypothesis that the functional significance of ITV in plant communities increases with environmental harshness. Moreover, in the Tibetan alpine meadows we studied, the opposing intraspecific and interspecific responses along a gradient of P availability appear to act as a buffering mechanism stabilizing the functional structure of communities on P deficient soils. Our novel conceptual and analytical framework provides a template for evaluating the generality of this favourable mismatch between intraspecific and interspecific responses in FD along environmental gradients. A free Plain Language Summary can be found within the Supporting Information of this article.

Foliar Nutrient Concentrations of European Beech in Switzerland: Relations With Nitrogen Deposition, Ozone, Climate and Soil Chemistry

Excess deposition of the mineral nutrient nitrogen (N) is a serious threat for European forests. Its effect on foliar nutrient concentrations of Fagus sylvatica, along with other predictors, was analyzed in the present study which bases on 30 year's observation data in 74 forest monitoring plots in Switzerland. The data include gradients in soil chemistry, climate, nitrogen (N) deposition and ozone concentration. This long-term forest monitoring study shows that foliar concentrations of phosphorus (P), magnesium (Mg) and potassium (K) decreased over time. Current foliar P concentrations indicate acute P deficiency, assessed both from the concentration and the N:P ratio thresholds. In addition, also the relation between N deposition and foliar concentrations of N and P changed over time. Initially, the N concentrations were positively and the P concentrations not correlated with N deposition. Today, N concentrations are negatively and P strongly negatively related, suggesting a progressive N saturation. Interactions between N deposition and soil chemistry suggest an impaired uptake of K and P at higher N loads. The decline of foliar Mg concentrations seems to be a result of soil acidification mediated by N deposition. Additionally, ozone impaired foliar P uptake. We could observe an increase in leaf weight over time while there was no time trend in P and K mass per leaf. This could be interpreted as a dilution effect but detailed regression analysis argues against the dilution hypothesis. Overall, the changing relation between N deposition and foliar N and P support the nitrogen saturation hypothesis.

Are arbuscular-mycorrhizal Alnus incana seedlings more resistant to drought than ectomycorrhizal and nonmycorrhizal ones?

Arbuscular mycorrhizas (AMs) prevail in warm and dry climates and ectomycorrhizas (EMs) in cold and humid climates. We suggest that the fungal symbionts benefit their host plants especially in the corresponding conditions. The hypothesis tested was that AM plants are more drought-resistant than EM or nonmycorrhizal (NM) plants. Grey alder (Alnus incana (L.) Moench) seedlings were inoculated with two species of either AM or EM fungi or none. In one controlled-environment experiment, there was a watering and a drought treatment. Another set of seedlings were not watered until permanent wilting. The AM plants were somewhat smaller than EM and NM, and at the early stage of the drought treatment, the soil-moisture content was slightly higher in the AM pots. Shoot water potential was highest in the AM treatment during severe drought, while stomatal conductance and photosynthesis did not show a mycorrhizal effect. In the lethal-drought set, the AM plants maintained their leaves longer than EM and NM plants, and the AM seedlings survived longer than NM seedlings. Foliar phosphorus and sulfur concentrations remained higher in AM plants than EM or NM, but potassium, copper and iron increased in EM during drought. The root tannin concentration was lower in AM than EM and drought doubled it. Although the difference in drought resistance was not large, the hypothesis was supported by the better performance of AM plants during a severe short-term drought. Sustained phosphorus nutrition during drought in AM plants was a possible reason for this. Moreover, the higher foliar sulfur and lower metal-nutrient concentrations in AM may reflect differences in nutrient uptake or (re)translocation during drought, which merit further research. The much larger tannin concentrations in EM root systems than AM did not appear to protect the EM plants from drought. The differential tannin accumulation in AM and EM plants needs further attention.

Jatropha curcas growth and productivity under different phosphorus doses

As informações sobre as exigências nutricionais de J. curcas são extremamente importantes no desenvolvimento do manual de adubação para a espécie, pois não há estudos conclusivos com fósforo e a demanda nutricional para este elemento ainda é desconhecida. O presente estudo teve como objetivo identificar e recomendar a adequada adubação fosfatada para o crescimento e produtividade de plantas de J. curcas. Os experimentos foram conduzidos em dois anos utilizando plantas de J. curcas com quatro meses de idade implantadas no espaçamento de 4 x 2 m. Utilizou-se o delineamento em blocos casualizados em arranjo Split plot com cinco tratamentos (doses de fósforo iguais a 0, 75, 150, 225 e 300 Kg ha-1 de P2O5) nas parcelas e anos de avaliações nas sub parcelas, cinco repetições e parcela de duas plantas. O superfosfato triplo foi utilizado como fonte de fósforo (P2O5) e as doses foram parceladas em cinco aplicações mensais iniciadas no primeiro ano em novembro e no segundo ano em outubro logo após a primeira chuva. Os resultados justificam a necessidade de atenção especial a adubação fosfatada por interferir decisivamente no vigor e produtividade de grãos de plantas de J. curcas. O elevado número de estômatos e vigoroso crescimento vegetativo de plantas de J. curcas foram obtidos com adubação nas doses entre 180 e 225 kg ha1 de P2O5. Recomenda-se para a planta de J. curcas a adubação fosfatada na dose de 208 kg ha-1 de P2O5 para obtenção de produtividade em torno de 140 kg ha-1 de P2O5 no 1º ano de cultivo e 214 kg ha-1 de P2O5 para obtenção de produtividade em torno de 600 kg ha-1 de P2O5no 2º ano de cultivo.

The legacy of logging

Forest Ecology Logging in tropical forests affects the future ecosystem functioning of the affected areas. Swinfield et al. investigated how logging affects the distribution of phosphorus, a key plant nutrient, over a wide area in Borneo. Spectroscopic imaging of forest canopies showed that the foliar concentrations of phosphorus were lower in logged than unlogged areas, indicating that soil phosphorus availability is decreased by logging. Because soil phosphorus is a key determinant of the tree species composition of tropical forests, the authors suggest that repeated logging of tropical forest on relatively infertile soils will lead to permanent, long-term changes in nutrient cycling and forest tree communities. Glob. Chang. Biol. 10.1111/gcb.14903 (2019).