Phosphorus Resorption Efficiency Research Articles

Effects of warming conditions on plant nitrogen–phosphorus stoichiometry and resorption of three plant species in alpine meadows on the Tibetan Plateau

Abstract Global climate change is expected to have a significant impact on ecosystems worldwide, especially for alpine meadows which are considered as one of the most vulnerable components. However, the effects of global warming on the plant nitrogen–phosphorus stoichiometry and resorption in alpine meadows remain unclear. Therefore, to investigate the plant nitrogen–phosphorus stoichiometry and resorption in alpine meadows on the Qinghai-Tibet Plateau, we conducted an artificial warming study using open-top chambers (OTCs) over the 3 years of warming period. We selected three dominant species, four height types of OTCs (0.4, 0.6, 0.8 and 1 m) and four warming methods (year-round warming, winter warming, summer–autumn–winter warming and spring–summer–autumn warming in the experiment) in this experiment. In our study, soil temperature significantly increased with increasing the height of OCTs under the different warming methods. Kobresia pygmaea presented an increase in nitrogen (N) limitation and Kobresia humilis presented an increase in phosphorus (P) limitation with increasing temperature, while Potentilla saundersiana was insensitive to temperature changes in terms of nitrogen and phosphorus limitations. Both nitrogen resorption efficiency:phosphorus resorption efficiency and N:P trends in response to rising temperatures were in the same direction. The differential responses of the chemical stoichiometry of the three species to warming were observed, reflecting that the responses of nitrogen and phosphorus limitations to warming are multifaceted, and the grassland ecosystems may exhibit a certain degree of self-regulatory capability. Our results show that using chemical dosage indicators of a single dominant species to represent the nitrogen and phosphorus limitations of the entire ecosystem is inaccurate, and using N:P to reflect the nutritional limitations might have been somewhat misjudged in the context of global warming.

Nutrient Variations and Their Use Efficiency of Pinus massoniana Seedling Tissues in Response to Low Phosphorus Conditions

Investigating the mechanisms by which plants adapt to low phosphorus content in ecosystems is crucial for nutrient dynamics division. Our study investigated the growth adaptation strategies of Pinus massoniana seedlings to low phosphorus conditions, including nutrient and non-structural carbohydrate (NSC) allocation, nutrient stoichiometry, and changes in nutrient resorption efficiency along a fact-based gradient. Our results showed that the total biomass and aboveground biomass proportion increased with substrate phosphorus content, reaching maximum biomass in the one-time phosphorus treatment. The nutrient concentration of components remained relatively stable, with the allocating preference to roots and needles under low phosphorus conditions. NSC was allocated as starch in fine roots and as soluble sugar in needles. Seedlings did not show signs of phosphorus limitation, even in the non-phosphorus group. The nitrogen resorption efficiency to phosphorus resorption efficiency ratio (NRE: PRE) of needles significantly varied between the high and low phosphorus treatments. In response to phosphorus deficiency, seedlings demonstrated homeostatic adjustments to maintain the relative stability of nutrient concentration. Fine roots and needles were prioritized to ensure nutrient uptake and photosynthetic product production. Additionally, it was necessary to differentiate the indicative function of nitrogen/phosphorus for various species and components, and NRE: PRE potentially provides a sensitive indicator of nutrient limitation status.

Leaf nitrogen and phosphorus resorption efficiencies are related to drought resistance across woody species in a Chinese savanna.

Leaf nutrient resorption and drought resistance are crucial for the growth and survival of plants. However, our understanding of the relationships between leaf nutrient resorption and plant drought resistance is still limited. In this study, we investigated the nitrogen and phosphorus resorption efficiencies (NRE and PRE), leaf structural traits, leaf osmotic potential at full hydration (Ψosm), xylem water potential at 50% loss of xylem-specific hydraulic conductivity (P50) and seasonal minimum water potential (Ψmin) for 18 shrub and tree species in a semiarid savanna ecosystem, in Southwest China. Our results showed that NRE and PRE exhibited trade-off against drought resistance traits (Ψosm and P50) across woody species. Moreover, this relationship was modulated by leaf structural investment. Species with low structural investment (e.g., leaf mass per area, leaf dry mass content and leaf construction cost [LCC]) tend to have high NRE and PRE, while those with high LCCs show high drought resistance, showing more negative Ψosm and P50.These results indicate that species with a lower leaf structural investment may have a greater need to recycle their nutrients, thus exhibiting higher nutrient resorption efficiencies, and vice versa. In conclusion, nutrient resorption efficiency may be a crucial adaptation strategy for coexisting plants in semiarid ecosystems, highlighting the importance of understanding the complex relationships between nutrient cycling and plant survival strategies.

Effect of urban pavement on nutrient strategies of common greening tree species in northern China

There are many factors that affect how urban tree species absorb and use nutrients, but little is known about the impact of pavement in urban areas. In this study, we selected four common urban tree species—Platanus x acerifolia, Metasequoia glyptostroboides, Robinia pseudoacacia, and Pinus thunbergii—and three pavement coverage categories—unpaved, semi-paved, and fully paved—in Qingdao, a typical city in northern China, to investigate changes in the leaf nutrient utilization strategies of tree species in paved environments. The nitrogen (N) resorption efficiency (NRE) and phosphorus (P) resorption efficiency (PRE) of R. pseudoacacia and the NRE of M. glyptostroboides increased in semi- and fully paved environments. Additionally, the N resorption proficiency of M. glyptostroboides increased significantly with pavement coverage, indicating that the biochemical limitation on N resorption was weakened. Similarly, the contents of N, P, and potassium (K) in R. pseudoacacia and N and K in M. glyptostroboides significantly increased with pavement coverage. This indicates that R. pseudoacacia, a nitrogen-fixing Fabaceae tree species, and M. glyptostroboides, a deciduous Cupressaceae tree species, can better adapt to pavement in urban settings, and even high pavement coverage levels can induce higher nutrient contents and resorption capacities. In addition, M. glyptostroboides showed potentially poor adaptability for N, P, and K uptake in the more stressful pavement environments, and P. x acerifolia showed relatively poor adaptability in P-limited environments. Robinia pseudoacacia associates with nodule-forming nitrogen-fixing bacteria, thus retaining more N in its leaves and showing a low NRE. These findings not only provide additional insight into tree growth at varying pavement coverages but also preliminary guidance for tree species selection to promote resilience in urban areas.

Altitudinal Patterns of Foliar Nutrients in Dominant Tree Species: Are Central Himalayan Forests Nutrient Stressed?

In forest ecosystems nutrient availability is one of the most important drivers of tree growth and ecosystem function. We studied changes in soil and foliar nutrients (N, P & K) and leaf N and P stoichiometry in eight dominant canopy and sub-canopy forest tree species of Central Himalayan forests occurring between 300 and 2200 m asl. Nutrient (N, P & K) concentration in leaves at bud break, mature and senescent stage varied significantly across the tree species. The nutrient resorption efficiency (NRE) varied significantly across the species and found ranging for N from 48.7 - 76.8%. Both the nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE) increased linearly with altitude (R2= 0.647 for NRE significant at p< 0.05; and R2 for PRE= 0.525; NS) pointing out that trees growing in temperate climate conserve nutrients more efficiently to withstand the slow mineralization due to cold climate. With the increasing altitude leaf life-span increases significantly (R2= 0.0025; p< 0.0074). ANOVA indicates that the foliar N and P and altitude were unrelated. The low N: P ratio, a measure of nutrient status of forest ecosystems at senescent leaf stage, found ranging from 9.97 in Q. floribunda to 18.8 in P. roxburghii points out that forests of the study region are nutrient stressed, partly due to low P mineralization in temperate climate, leaching of nutrients due to heavy monsoon rain, and poorly developed underlying geology. Thus, the Central Himalayan forests are characterized by high NRE and low growth rate with increasing altitude. Winter season warming might help improve the nutrient availability in the forest floor and nutrient uptake to enhance nutrient cycling and biomass productivity in these forests.

Nutrient content and resorption efficiency of leaves of broad-leaved trees along altitudes in Wuyi Mountains, China.

To reveal the variation of leaf nutrient utilization strategies with altitude gradient in subtropical mountain broadleaved trees, 44 species of broadleaved trees at different altitudes (1400, 1600 and 1800 m) in Wuyi Mountains were selected to measure nutrient content, stoichiometric ratio, and nutrient resorption efficiency of green and senescent leaves, and analyzed their allometric growth relationships. The results showed that nitrogen (N) and phosphorus (P) contents in green leaves were significantly higher than those in senescent leaves, which increased with the increases of altitude. The average values of phosphorus resorption efficiency (PRE) and nitrogen resorption efficiency (NRE) were 48.3% and 34.9%, respectively. PRE was significantly higher than NRE. There was no significant difference in nutrient resorption efficiency with altitude. NRE had positive isokinetic growth with and mature leaf N content at low altitude (1400 m) and negative allometry growth with senescent leaf N content at high altitude (1800 m). PRE and N and P contents of senescent leaves had negative isokinetic growth at low altitude (1400 m) and negative allometry growth at high altitudes (1600 and 1800 m). PRE-NRE allometric growth index was 0.95 at each altitude. The nutrient contents of green and senescent leaves increased with the increases of altitude, but altitude did not affect nutrient resorption efficiency. Plants preferred to re-absorbed P from senescent leaves. Nutrient resorption efficiency of leaves at high altitude affected the nutrient status of senescent leaves.

Effects of simulated precipitation gradients on nutrient resorption in the desert steppe of northern China.

Changes in rainfall induced by climate change will likely influence the utilization of water resources and affect the nutrient cycle in plants in the water-limited desert steppe. In order to understand the response of nitrogen and phosphorus resorption characteristics of plant leaves to precipitation changes, this study compared the nitrogen (N) resorption efficiency, phosphorus (P) resorption efficiency and influencing factors of plants in a desert steppe through water treatment experiments. A 4-year field experiment was performed to examine the response and influencing factors of nitrogen (N) and phosphorus resorption efficiency of five dominant plants in Stipa breviflora desert steppe to simulated precipitation change in Inner Mongolia, with four simulated precipitation gradients including reducing water by 50%, natural precipitation, increasing water by 50%, increasing water by 100%. Compared with natural precipitation, increasing water by 100% significantly increased soil moisture, and significantly increased the aboveground biomass of S. breviflora, C. songorica, A. frigida, decreased the N concentrations in green leaves of S. breviflora, Cleistogenes songorica, Artemisia frigida, Kochia prostrata, decreased the N concentrations in senesced leaves of C. songorica, decreased the P concentrations in green leaves of K. prostrata and Convolvulus ammannii, decreased the NRE of S. breviflora. NRE was significantly negatively correlated with N concentration in senesced leaves, and PRE was significantly negatively correlated with P concentration in senesced leaves. Increasing water indirectly reduces NRE by reducing plant leaf green leaves nitrogen concentration, and decreasing water indirectly reduces PRE by reducing soil moisture.

Dynamics of plant nutrient requirements and acquisition strategies after afforestation: A study on the Loess Plateau, China

Plant nutrient requirements and acquisition strategies are critical to understand the net primary productivity and community stability in terrestrial ecosystems. However, the current knowledge regarding this subject is limited, especially in the case of afforestation. Therefore, we selected four Robinia pseudoacacia (RP) forests (15-, 21-, 31-, and 46-year-old forests) in the Loess Plateau, and analyzed the nutrients in the plant organs, litter, and soil, along with the extracellular enzyme activities (EEAs), microbial biomass, and mineralization rate. In addition, the biomass of RP was determined using an allometric growth model. The results showed that during afforestation, the nitrogen and phosphorus requirement of RP increased significantly, from 3.97 to 18.14 g·m−2·year−1 and 0.17 to 0.71 g·m−2·year−1, respectively, while the nutrient resorption efficiency and the contributions of nutrient resorption to the total nutrient requirements significantly decreased. Meanwhile, the ratio of nitrogen to phosphorus resorption efficiency (NRE:PRE) significantly increased with afforestation, but were less than 1 which may indicate the phosphorus limitation of RP decreased. In addition, the vector angle significantly increased form 44.80° to 49.51° after afforestation, which may indicate the phosphorus limitation of soil microorganisms increased. Meanwhile, the vector angle was significantly positive with phosphorus mineralization rate and NRE:PRE, which may show that soil microorganisms activity alleviate the phosphorus limitation of plants. Collectively, our study contributes to a better understanding of nutrient cycling above and below the ground.

Leaf litter chemistry and its effects on soil microorganisms in different ages of Zanthoxylum planispinum var. Dintanensis

BackgroundLeaf litter is the products of metabolism during the growth and development of plantation, and it is also an important component of nutrient cycling in plantation ecosystems. However, leaf litter chemistry and its effects on soil microorganisms in different ages, as well as the interactions between chemical components in leaf litter have been rarely reported. Based on this, this paper took Zanthoxylum planispinum var. dintanensis (hereafter Z. planispinum) plantations of 5–7, 10–12, 20–22, and 28–32 years old as the objects. By using one-way ANOVA, Pearson correlation analysis and redundancy analysis, we investigated leaf litter chemistry and its effects on soil microorganisms in different ages, and to reveal internal correlation of various chemical components in leaf litter, which can provide a scientific basis for the regulation of soil microbial activity in plantations.ResultsThe variation of organic carbon with plantation age was more stable compared to total nitrogen and phosphorus of leaf litter. Nitrogen resorption was stronger than phosphorus resorption efficiency in Z. planispinum, and resorption efficiencies of leaf nitrogen and phosphorus for different ages were lower than the global average. Total nitrogen was highly significantly positively correlated with lignin, and total potassium was significantly positively correlated with tannin, suggesting the increase of inorganic substances in leaf litter would promote the accumulation of secondary metabolites. The leaf litter chemical traits explained up to 72% of soil microorganisms, where lignin was positively correlated with fungi and negatively correlated with bacteria, indicating that fungi are able to decompose lower quality litter and can break down complex and stable organic compounds more rapidly than bacteria. The nutrient elements carbon and nitrogen in the leaf litter and their interrelationship also have a great impact on soil microorganisms, because carbon is not only the element that provides energy, but also the element with the largest content in the microbiota.ConclusionsThe sustained increase in inorganic nutrients of leaf litter did not favor the decomposition of secondary metabolites, but rather inhibited the degradation of leaf litter. The significant positive effect of the leaf litter chemistry on soil microorganisms indicates the important role of leaf litter in promoting nutrient cycling in Z. planispinum plantations.

Responses of nitrogen and phosphorus resorption of understory plants to microscale soil nutrient hetero-geneity in Chinese fir plantation.

We compared the interspecific differences in leaf nutrient resorption of two dominant understory species (Lophatherum gracile and Oplimenus unulatifolius), and analyzed the correlations between the intraspecific efficiency of leaf nutrient resorption and nutrient properties of soil and leaves in Chinese fir plantation. The results showed high soil nutrient heterogeneity in Chinese fir plantation. Soil inorganic nitrogen content and available phosphorus content varied from 8.58 to 65.29 mg·kg-1 and from 2.43 to 15.20 mg·kg-1 in the Chinese fir plantation, respectively. The soil inorganic nitrogen content in O. undulatifolius community was 1.4 times higher than that in L. gra-cile community, but there was no significant difference in soil available phosphorus content between the two communities. Both leaf nitrogen and phosphorus resorption efficiency of O. unulatifolius was significantly lower than that of L. gracile under the three measurement bases of leaf dry weight, leaf area, and lignin content. Resorption efficiency in L. gracile community expressed on leaf dry weight was lower than that expressed on leaf area and lignin content, while resorption efficiency expressed on leaf area was the lowest in O. unulatifolius community. The intraspecific resorption efficiency was significantly correlated with leaf nutrient contents, but was less correlated with soil nutrient content, and only the nitrogen resorption efficiency of L. gracile had significant positive correlation with soil inorganic nitrogen content. The results indicated that there was significant difference in the leaf nutrient resorption efficiency between the two understory species. Soil nutrient heterogeneity exerted a weak effect on the intraspecific nutrient resorption, which might be attributed to high soil nutrient availability and potential disturbance from canopy litter in Chinese fir plantation.

Arbuscular mycorrhizal fungi alter plant N and P resorption of dominant species in a degraded grassland of northern China

Plant nutrient resorption is an important regulator of biogeochemical cycling and decomposition. Arbuscular mycorrhizal fungi (AMF) may influence this process by helping plants absorb nutrients, although the mechanism by which this occurs remains unclear. We examined variations in nutrient resorption over a period of 3 years in three dominant species, namely, Artemisia frigida, Potentilla acaulis, and Stipa krylovii, treated with or without fungicide in a degraded grassland in Inner Mongolia in 2017. Our results showed that AMF increased the nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE) in A. frigida but decreased NRE and PRE in S. krylovii and PRE in P. acaulis. The inconsistent nutrient resorption responses of A. frigida and S. krylovii to AMF were primarily attributed to the changes in biomass in the presence of AMF, thereby changing the nutrient requirements. For P. acaulis, the reduction in PRE with AMF was because AMF-induced its N limitation, which is consistent with the relative nutrient resorption hypothesis. AMF increased internal nutrient cycling in A. frigida, which may promote its dominance in degraded grassland in Inner Mongolia, China. Moreover, AMF reduced senesced leaf N concentrations, thereby reducing the carbon (C):N ratio in senesced leaves, which may affect nutrient return to the soil. Our findings indicate that AMF substantially affect the biomass and nutrient requirements of dominant plant species, potentially leading to changes in nutrient resorption during grassland degradation, which may provide a deep insight into plant nutrient retranslocation in degraded grasslands.

Global distributions of foliar nitrogen and phosphorus resorption in forest ecosystems

Nutrient resorption is an important mechanism for nutrient conservation and can maintain ecosystem stoichiometry. Here, we examined the global-scale variation of nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE) by analyzing observations from 218 published papers. We used Pagel's λ to test the phylogenetic limitation on NRE and PRE and applied the random forest model to assess biotic and abiotic drivers, which included climate, soil, species characteristics, and topographical factors, and predicted the global NRE and PRE distributions. We found that NRE and PRE had oppositing trends among climatic zones, plant functional groups, and foliar nitrogen (N) to phosphorus (P) ratios. Nutrient resorption was higher in ectomycorrhizal trees than in arbuscular mycorrhizal trees. Moreover, foliar NRE and PRE were not linked to phylogeny. On average, the random forest overall explained 38 % (21 %–55 %) variation in NRE and 36 % (16 %–55 %) variation in PRE. Both NRE and PRE varied greatly with climate and soil organic carbon (SOC). The spatial variation of NRE and PRE was coupled to N-limitation and P-limitation, respectively. Our evaluation of the factors that influenced NRE and PRE and their global distributions, and our novel approach for evaluating plant utilization of nutrients, advances our understanding of the relative stability of ecosystem randomness in forest ecosystems and the global forest nutrient cycle.

Altitude and slope aspects as the key factors affecting the change of C:N:P stoichiometry in the leaf-litter-soil system of alpine timberline ecotones of the Sygera Mountains in Southeast Tibet, China

Understanding the altitudinal distribution patterns of ecological stoichiometry is essential for understanding biogeochemical processes in mountainous forests. However, the changes in ecological stoichiometry throughout the leaf-litter-soil system on the different slope aspects in mountainous forests ecosystems are not fully understood. To fill these gaps, we examined the altitudinal patterns of C:N:P stoichiometry in the leaf-litter-soil system and nutrient resorption of dominant tree species in the alpine timberline ecotones on the sunny and shady slopes of the Sygera Mountains in Southeast Tibet, China. Three timberline plants were selected: Sabina saltuaria (S. saltuaria), Abies georgei (A. georgei) and Rhododendron aganniphum (R. aganniphum). The C, N, and P contents and C:N:P stoichiometry of R. aganniphum in the leaf and foliar litter varied widely along the altitudes, and those of soil showed similar trends. The leaf C:N of R. aganniphum, soil C, and soil C:N on the sunny slope increased with increasing altitudes. Furthermore, the N and P contents in the leaf and foliar litter of timberline plants on the shady slope were significantly higher than those on the sunny slope, whereas the C, C:N, C:P, and N:P ratios in the leaf and foliar litter exhibited the opposite trend. R. aganniphum had the highest nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE), whereas A. georgei had the lowest. The PRE of R. aganniphum increased with increasing altitudes, which may be driven by the soil C:N ratio. According to leaf N:P ratios and the relative resorption hypothesis, the leaf N:P ratio was 5.55, 8.70 and 2.86 corresponding to NRE equal to PRE for S. saltuaria, A. georgei and R. aganniphum, respectively. It suggests that the timberline ecotones plants in this study were P-limited, although this limitation may not be responsible for the formation of timberlines in the the Sygera Mountains. Varying degrees of correlations exist between element contents, stoichiometry ratios and nutrient resorption efficiency. Overall, our results revealed that altitude and slope aspects are the key factors affecting the change of C:N:P stoichiometry in the leaf-litter-soil system.

Effect of shrub encroachment on leaf nutrient resorption in temperate wetlands in the Sanjiang Plain of Northeast China

BackgroundNutrient resorption is an important plant nutrient conservation strategy in wetlands. However, how shrub encroachment alters plant nutrient resorption processes is unclear in temperate wetlands. Here, we collected green and senesced leaves of common sedge, grass, and shrub species in wetlands with high (50–65%) and low (20–35%) shrub covers in the Sanjiang Plain of Northeast China, and assessed the impact of shrub encroachment on leaf nitrogen (N) and phosphorus (P) resorption efficiency and proficiency at both plant growth form and community levels.ResultsThe effects of shrub cover on leaf nutrient resorption efficiency and proficiency were identical among shrubs, grasses, and sedges. Irrespective of plant growth forms, increased shrub cover reduced leaf N resorption efficiency and proficiency, but did not alter leaf P resorption efficiency and proficiency. However, the effect of shrub cover on leaf nutrient resorption efficiency and proficiency differed between plant growth form and community levels. At the community level, leaf N and P resorption efficiency decreased with increasing shrub cover because of increased dominance of shrubs with lower leaf nutrient resorption efficiency over grasses and sedges. Accordingly, community-level senesced leaf N and P concentrations increased with elevating shrub cover, showing a decline in leaf N and P resorption proficiency. Moreover, the significant relationships between leaf nutrient resorption efficiency and proficiency indicate that shrub encroachment increased senesced leaf nutrient concentrations by decreasing nutrient resorption efficiency.ConclusionsThese observations suggest that shrub encroachment reduces community-level leaf nutrient resorption efficiency and proficiency and highlight that the effect of altered plant composition on leaf nutrient resorption should be assessed at the community level in temperate wetlands.

Relationships between tree functional traits and leaf nitrogen and phosphorus resorption efficiencies in subtropical young plantations

We examined the relationship between tree functional traits and leaf nitrogen and phosphorus resorption efficiencies across 29 species in 3-year-old pure plantations in subtropical China. The results showed that the average nitrogen (NRE) and phosphorus (PRE) resorption efficiencies in 29 young plantations were 50.5% and 57.3%, respectively. The average NRE of 22 arbuscular mycorrhizal (AM) tree species was 52.7%, significantly higher than that of the seven ectomycorrhizal (EM) tree species (45.1%). NRE was positively correlated with fine root tissue density across the 29 tree species. PRE was positively correlated with root diameter in the seven EM tree species. Functional traits of 22 AM tree species were not associated with NRE and PRE. Among all of the 29 tree species, mycorrhizal type, specific leaf area, fine root tissue density, leaf thickness, and the interaction effects of mycorrhizal type with leaf thickness explained 27% variation in NRE. Specific root length, fine root carbon content, fine root carbon to nitrogen ratio, mycorrhizal type, leaf carbon content, and the interaction effects of mycorrhizal type with leaf carbon content explained 35% variation in PRE. Root functional trait of subtropical species could predict nitrogen and phosphorus resorption efficiencies. The model with multiple functional traits could better reveal the relative importance of different biological factors on nutrient resorption efficiency.

Foliar resorption of nitrogen and phosphorus in Alcea apterocarpa (Malvaceae) in different habitats types

The study goal is to reveal foliar resorption patterns of Alcea apterocarpa populations in different habitats (riverbank, meadow and forest clearing) in the Central Black Sea Region of Turkey. We determined foliar nitrogen and phosphorus resorption, considering proficiency and efficiency. The resorption efficiency was also calculated using the mass loss correction factor (MLCF). Some studies indicated that MLCF provides unbiased resorption values. Phosphorus resorption proficiencies (PRP) of species were intermediate level, while nitrogen resorption proficiencies (NRP) were complete level. Phosphorus resorption efficiencies (PRE) were intermediate level for all habitats considering MLCF, while in meadow habitat, PRE was complete level without MLCF. Nitrogen resorption efficiencies (NRE) were intermediate level for all habitats without MLCF, but NRE values of meadow and forest clearing were incomplete level as using MLCF. Green leaf N/P ratios of A. apterocarpa were higher in riverbank, while senescence leaf N/P ratios were higher in meadow habitat. Only, the regression relationship between PRP and green leaf N/P ratio was not significant.

Divergent leaf nutrient-use strategies of coexistent evergreen and deciduous trees in a subtropical forest

Abstract Evergreen and deciduous species coexist in the subtropical forests in southeastern China. It has been suggested that phosphorus (P) is the main limiting nutrient in subtropical forests, and that evergreen and deciduous species adopt different carbon capture strategies to deal with this limitation. However, these hypotheses have not been examined empirically to a sufficient degree. In order to fill this knowledge gap, we measured leaf photosynthetic and respiration rates, and nutrient traits related to P-, nitrogen (N)- and carbon (C)-use efficiencies and resorption using 75 woody species (44 evergreen and 31 deciduous species) sampled in a subtropical forest. The photosynthetic N-use efficiency (PNUE), respiration rate per unit N and P (Rd,N and Rd,P, respectively) of the deciduous species were all significantly higher than those of evergreen species, but not in the case of photosynthetic P-use efficiency. These results indicate that, for any given leaf P, evergreen species manifest higher carbon-use efficiency (CUE) than deciduous species, a speculation that is empirically confirmed. In addition, no significant differences were observed between deciduous and evergreen species for nitrogen resorption efficiency, phosphorus resorption efficiency or N:P ratios. These results indicate that evergreen species coexist with deciduous species and maintain dominance in P-limited subtropical forests by maintaining CUE. Our results also indicate that it is important to compare the PNUE of deciduous species with evergreen species in other biomes. These observations provide insights into modeling community dynamics in subtropical forests, particularly in light of future climate change.

Monthly Dynamical Patterns of Nitrogen and Phosphorus Resorption Efficiencies and C:N:P Stoichiometric Ratios in Castanopsis carlesii (Hemsl.) Hayata and Cunninghamia lanceolata (Lamb.) Hook. Plantations

Trees can resorb nutrients to preserve and reuse them before leaves fall, which could efficiently adapt to environmental changes. However, the nutrient requirements of trees in different months with seasonal climate changes are often neglected. In this study, we selected plantations of an evergreen broadleaf tree (Castanopsis carlesii (Hemsl.) Hayata) and a coniferous tree (Cunninghamia lanceolate (Lamb.) Hook.) in the subtropics. The monthly dynamics of leaf nitrogen (N) and phosphorus (P) resorption efficiencies and C:N:P stoichiometric ratios were checked along a growing season from April to October 2021. Trees in both plantations exhibited efficient N and P resorption but with significant monthly variations. The N and P resorption efficiencies in the Cunninghamia lanceolata plantation ranged from 34.26% to 56.28% and 41.01% to 54.85%, respectively, and were highest in September. In contrast, N and P resorption efficiencies in the Castanopsis carlesii plantation ranged from 11.25% to 34.23% and 49.22% to 58.72%, respectively, and were highest in July. Compared with the Cunninghamia lanceolata, the C:N of the Castanopsis carlesii plantation was significantly lower, while its C:P was significantly higher in May and September. The Castanopsis carlesii plantation was strongly limited by P (the N:P ratios in mature leaves were higher than 20), whereas the Cunninghamia lanceolata plantation might be limited by both N and P (the N:P ratios in mature leaves were between 10 and 20). In addition, the statistical analyses revealed that temperature and precipitation were significantly associated with N and P resorption efficiencies, but the relationships were controlled by forest types. These findings highlight that efficient resorption of N and P may be beneficial in regulating nutrient limitation and balance in subtropical forest ecosystems. These results contribute to the understanding of N and P utilization strategies of trees and provide a theoretical basis for vegetation management in the subtropics.

Phenotypic plasticity contributes more to the variations in nutrient resorption than genetic differentiation in a grassland dominant

Abstract Phenotypic plasticity and genetic differentiation are the two important processes determining the leaf nutrient resorption among and within plant species, which is critical for understanding the adaptability of plants. However, relative contributions of these two processes have never been quantified at a large geographical scale. Here, we investigated intraspecific variations in nutrient resorption among 14 Stipa breviflora populations along a latitude gradient in 2018 and 2019. Furthermore, we sow seeds from these populations in two common gardens at different latitudes and examined the variations in nutrient resorption. Our results showed that nitrogen and phosphorus resorption efficiency (NRE and PRE) among S. breviflora populations in nature were positively related to latitude, while this trend disappeared in the common gardens. The heritability of NRE and PRE was 11.45% and 16.78%, respectively. These results suggested that phenotypic plasticity contributed much more than genetic variation to nutrient resorption of S. breviflora. Moreover, the structural equation modelling (SEM) suggested that latitude indirectly affected nutrient resorption mainly by altering soil nutrients. With the increasing of latitude, soil nutrients decreased while nutrient resorption increased. This phenomenon indicated that the main process regulating nutrient resorption is negative feedback to soil nutrient availability. Our study provides new insights into the role of nutrient resorption in plant adaptations to geographic variations. Read the free Plain Language Summary for this article on the Journal blog.

Yükseklik Gradiyenti Boyunca Diospyros kaki L.’de Yaprak Azot, Fosfor, Karbon Değişimi ve N ve P Rezorbsiyonu

In the present study, nitrogen (N), phosphorus (P), carbon (C) levels and nutrient contents, N and P resorption were investigated in Diospyros kaki L., whose leaves has a strong antioxidant property and is cultivated in the Eastern Black Sea Region. The research was carried out at four different locations where Diospyros kaki was grown within the provincial borders of Trabzon. Leaf samples were taken from these selected locations monthly from May to December. Soil samples were taken from a depth of 0-20 cm from each locality. Soil N, P and C analysis were also determined. There were important differences in N (%) concentration and N (g dm-2) content values in terms of localities. N, P and C (%) concentration values significantly varied among months. Similarly, there were notable differences in N and P (g dm-2) values depending on months. Nitrogen and phosphorus resorption efficiency (RE) values were below stated boundaries at only 796 m. Nitrogen and phosphorus resorption proficiency (RP) values significantly varied between localities.