Resource Acquisition Strategies Research Articles

Plant trait-based life strategies of overlapping species vary in different succession stages of subtropical forests, Eastern China

Plants growing in forests at different succession stages in diverse habitats may adopt various life strategies from the perspective of plant functional traits. However, species composition differs with forest succession, and the effects of forest succession on traits have often been explored without considering the effects of species identity. We comprehensively investigated intraspecific variations in 12 traits of six overlapping species (two tree species and four understory shrub species) in three typical subtropical evergreen broad-leaved forests at different succession stages in eastern China. We found that intraspecific variations differed among traits. Fine root specific length presented large intraspecific variation, leaf area, specific leaf area and fine root tissue density showed medium intraspecific variations, and other traits displayed small intraspecific variations. Trees and understory shrubs in the early-stage forest exhibited higher leaf thickness, dry matter contents and tissue densities of leaves, roots, twigs, and stems and lower leaf area and specific leaf area. Those in the medium- and late-stage forests displayed contrasting trait characteristics. From the perspective of plant functional traits, plants in the early-stage forest formed a series of trait combinations for a resource conservative strategy with a low growth rate to adapt to fragile habitats with poor soil nutrients and changeable soil temperature and humidity, and those in the medium- and late-stage forests (especially the former) formed converse trait combinations for a resource acquisitive strategy with a high growth rate to adapt to low light availability and strongly competitive habitats. Our study reveals that plants in forests at different succession stages adopt various life strategies and provides data to the TRY and China plant trait databases.

Root phosphatase activity is a competitive trait affiliated with the conservation gradient in root economic space

BackgroundThe diversity of resource acquisition strategies of plant roots determines the species coexistence patterns to a certain extent. However, few root physiological traits have been investigated, such as root phosphatase activity (PA) that affects plant phosphorus (P) uptake. MethodsRoot PA and classical root functional traits were investigated for 21 coexisting species in a deciduous broad-leaved forest in warm temperate-subtropical transition zone, China. We analyzed the root order variation of absorptive fine root PA, clarified the attribution of root PA in root economic space (RES) and the different P acquisition strategies of co-occurring species based on the multidimensional RES theory, and determined the dominant factors affecting interspecific variation in root PA. ResultsThere was no distinct pattern of PA variation with root order in the first three root orders of absorptive fine roots, and root PA was constrained by phylogeny. Root PA is a competitive trait affiliated with the conservation gradient in RES. The tight linkages among root PA, mycorrhizal colonization, diameter, specific root length, and nitrogen concentration suggested trade-offs among P acquisition strategies of co-occurring species, i.e. species with long and fine roots acquire inorganic P by actively exploring the soil and secreting phosphatase to mineralize and hydrolyze organic P, while species with short and thick roots obtain P mainly by investing C in mycorrhizal partners. ConclusionsCollectively, our study provides an insight into the forest species coexistence in climatic transition zones, i.e. species coexistence mechanisms based on diverse phosphorus acquisition strategies.

Effect of forest structure and management on the functional diversity and composition of understorey plant communities

AbstractQuestionsDo forest structural parameters related to stand heterogeneity enhance functional diversity (FD) of understorey plant communities? Do FD and functional composition of understorey plant communities vary between high‐forest (HF) and old coppices‐with‐standard (oldCWS) management types? Are HF stands characterized by a higher FD than oldCWS?LocationSubmediterranean beech forests of Montagne della Duchessa Reserve (central Italy).MethodsWe sampled 57 (20 m × 20 m) forest plots, 29 oldCWS and 28 HF stands, where we recorded plant species cover abundance. We used Leaf–Height–Seed and clonal traits, and run multiple separate linear models to quantify the effect of forest structural parameters and management types on FD and functional composition of understorey plant communities.ResultsWe found that increasing lying deadwood enhanced FD of specific leaf area (SLA) through micro‐environmental heterogeneity of soil fertility regardless of management type. We also found that increased horizontal stratification filtered the range of plant sizes, probably through light reduction. HF management enhanced FD of SLA and clonal traits through micro‐environmental heterogeneity, while reducing the FD of plant size and seed mass. HF tended to select plant communities characterized by high resource acquisition strategies but lower persistence between ramets, possibly as an effect of more mature forest conditions.ConclusionOur study suggests that understorey plant community diversity and composition change in response to forest structure and management. Combining Leaf–Height–Seed with clonal traits offers a promising framework for understanding and predicting plant response to management practices.

Fagus sylvatica and Quercus pyrenaica: Two neighbors with few things in common

BackgroundThe Iberian Peninsula comprises one of the largest boundaries between Mediterranean and Eurosiberian vegetation, known as sub-Mediterranean zone. This ecotone hosts many unique plant species and communities and constitutes the low-latitude (warm) margin of numerous central European species which co-occur with Mediterranean vegetation. Two of the main species found in this region are the Eurosiberian European beech (Fagus sylvatica L.) and the Mediterranean Pyrenean oak (Quercus pyrenaica Willd.). It remains unclear how the different physiological and adaptive strategies of these two species reflect their niche partitioning within a sub-Mediterranean community and to what extent phenotypic variation (intraspecific variability) is driving niche partitioning across Eurosiberian and Mediterranean species. MethodsWe quantified functional niche partitioning, based on the n-dimensional hypervolume to nine traits related to resource acquisition strategies (leaf, stem and root) plus relative growth rate as an additional whole-plant trait, and the environmental niche similarity between Pyrenean oak and European beech. Further, we analyzed the degree of phenotypic variation of both target species and its relationship with relative growth rates (RGR) and environmental conditions. Plant recruitment was measured for both target species as a proxy for the average fitness. ResultsSpecies’ functional space was highly segregated (13.09% overlap), mainly due to differences in niche breadth (59.7%) rather than niche replacement (25.6%), and beech showed higher trait variability, i.e., had larger functional space. However, both species shared the environmental space, i.e., environmental niches were overlapped. Most plant traits were not related to abiotic variables or RGR, neither did RGR to plant traits. ConclusionsBoth target species share similar environmental space, however, show notably different functional resource-use strategies, promoting a high complementarity that contributes to maintaining a high functionality in sub-Mediterranean ecosystems. Therefore, we propose that conservation efforts be oriented to preserve both species in these habitats to maximize ecosystem functionality and resilience.

Accept, deny or cultivate – how entrepreneurs evaluate and exploit potential value added by equity investors

Venture capitalists and business angels can provide startups with many important resources. However, previous research has mainly focused on the value-adding side of investors while ignoring the value-exploiting side of entrepreneurs. This study examines how entrepreneurs evaluate and respond to investors’ non-financial support. We use a combination of inductive and deductive thematic analysis to analyze 19 semi-structured interviews with Vietnamese entrepreneurs. We find that entrepreneurs assess investors’ inputs based on the startup’s resource acquisition strategy, either in terms of how these inputs fit into the firm’s current resource gaps or in terms of how they lead to revisions in the firm’s strategy. Three factors can influence the resource-acquisition strategy: entrepreneurs’ resource preference, the firm’s stage of development, and its operating environment. We identify a psychological factor that shapes the post-evaluation response of entrepreneurs, i.e. their belief about the fixed/growth nature of investor abilities. In case investors’ inputs do not match or modify the current resource-acquisition strategy, founders who believe that investors’ abilities are fixed tend to adopt a rejection and avoidance response. In contrast, founders who view investor abilities as a malleable quality seek to improve investors’ understanding about their business and increase their motivation to help the company.

How nutrient loads influence microbial-derived carbon accumulation in wetlands: A new insight from microbial metabolic investment strategies

Excessive anthropogenic nutrient inputs often lead to the degradation of wetland ecosystems and a decrease in carbon sink capacity. Microbial-derived carbon is increasingly recognized as an important precursor for organic carbon formation, which is controlled by the balance between microbial anabolic and catabolic processes. Shifts in microbial metabolic investment under nutrient load disturbance are key, but understudied, components of microbial-derived carbon turnover. Here, the roles of the distinct life-history traits and cooperation degree of key microbial assemblies in regulating microbial-derived carbon accumulation in a wetland receiving treated wastewater were firstly assessed by combining microbial biomarkers and genomic approaches. It was found that microbial-derived carbon was an important source of organic carbon in wetlands, and strongly associated with several microbial assemblies with specific trait strategies. Further analysis demonstrated that high growth yield strategists were mainly associated with microbial necromass accrual, while microbial biomass was more dominated by resource acquisition strategies in nutrient-imbalanced wetlands. A significant positive relationship between positive cohesion and microbial-derived carbon indicated that cooperative behavior among taxa promoted the production and accumulation of microbial-derived carbon. Moreover, resource stoichiometric balance, including C:N and C:P, was identified as an important driver of shifts in microbial metabolic investment strategies. The decreased C:N ratio led to a shift from resource acquisition strategies to high growth yield strategies for the microbial community, which facilitated microbial necromass accrual along the N-limited wetland, while the increased C:P ratio caused by excessive P deposition in sediments limits microbial cooperative growth to some extent. This study highlighted the importance of stoichiometric balance in mediating microbial growth metabolism and, in turn, enhancing the carbon sink capacity of wetlands.

Plant diversity effects on herbivory are related to soil biodiversity and plant chemistry

Abstract Insect herbivory is a key process in ecosystem functioning. While theory predicts that plant diversity modulates herbivory, the mechanistic links remain unclear. We postulated that the plant metabolome mechanistically links plant diversity and herbivory. In late summer and in spring, we assessed individual plant above‐ground herbivory rates and metabolomes of seven plant species in experimental plant communities varying in plant species diversity and resource acquisition strategies. In the same communities, we also measured plant individual biomass as well as soil microbial and nematode community composition. Herbivory rates decreased with increasing plant species richness. Path modelling revealed that plant species richness and community resource acquisition strategy correlated with soil community composition. In particular, changes in nematode community composition were related to plant metabolome composition and thereby herbivory rates. Synthesis. These results suggest that soil community composition plays an important role in reducing herbivory rates with increasing plant diversity by changing plant metabolomes.

Delaying drought-driven leaf cell damage may be the key trait of invasive trees ensuring their success in the Mediterranean basin.

Invasive alien species (IAS) threaten the biodiversity richness of the Mediterranean basin, a drought-prone region. However, our knowledge on the adaptive strategies of IAS for facing Mediterranean drought summers is still incomplete. The aim of the present study is to compare the water relations and the critical relative water content (RWC) values leading to loss of cell rehydration capacity of two Mediterranean basin IAS (i.e., Ailanthus altissima (Mill.) Swingle and Robinia pseudoacacia L.) versus two co-occurring native species (i.e., Fraxinus ornus L.and Quercus pubescensWilld.). Study IAS showed higher values of water potential at turgor loss point and osmotic potential at full turgor, lower values of modulus of elasticity and leaf mass area but higher photosynthesis rate, even during the summer, with respect to the Mediterranean native species. These findings supported the hypothesis that IAS are characterized by a resource acquisitive strategy coupled with a safety-efficiency trade-off, compared with Mediterranean native species. However, similar leaf RWC thresholds leading to loss of cell rehydration capacity were recorded in the two groups of species. Moreover, IAS showed higher saturated water content and capacitance values compared with the co-occurring species. Overall, our results suggest that the success of Mediterranean IAS is driven by their ability to delay dehydration damage of mesophyll cells during Mediterranean summer drought, thereby supporting their distinctive high carbon assimilation rate.

Lianas have a faster resource acquisition strategy than trees: Below‐ground evidence from root traits, phylogeny and the root economics space

Abstract The competitive advantage of lianas over trees has been widely documented in studies of their leaf functional traits across diverse habitats; however, the relative contribution of root functional traits to the competitive superiority of lianas over trees has not yet been evaluated. The aim of this study was to explore the root functional traits, phylogenetic structure of these traits and root trait dimensions of lianas to clarify why lianas can outperform trees. We sampled 69 liana species from tropical and temperate forests in China and measured nine key functional traits of first‐order roots of each species, including morphological, architectural, anatomical and chemical traits, as well as the percentage of mycorrhizal colonization. Data on these traits were then compared with similar data of 127 tree species from the same biome obtained from the Global Root Traits (GRooT) database and our previous studies. Liana roots had lower construction costs and could acquire resources more rapidly compared with tree roots. Significant differences were observed in most tree root traits between tropical and temperate sites. However, no significant differences were observed in any of the liana root traits between tropical and temperate sites, apart from the root branching ratio. Lianas showed much weaker phylogenetic conservatism in their root traits than trees when species were pooled across sites. Phylogenetic constraint was lower for nearly all root traits of both temperate lianas and trees compared with those of tropical lianas and trees. The root economics space of lianas and trees had two orthogonal dimensions with ‘conservation’ and ‘collaboration’ axes. However, lianas occupied the trait space with higher root nitrogen concentration and greater specific root length, showing ‘fast’ resource acquisition strategy, while trees placed opposite space and exhibited relatively ‘slow’ strategy. Synthesis. The ability of lianas to outcompete trees in harsh environments might be explained by their faster resource acquisition strategy and the lower phylogenetic constraint in root traits. Generally, lianas might play an increasingly important role in the structure and function of forest ecosystems in the future with ongoing habitat fragmentation and climate change.

Coupling of leaf elemental traits with root fungal community composition reveals a plant resource acquisition strategy in a desert ecosystem

Coupling of leaf elemental traits with root fungal community composition reveals a plant resource acquisition strategy in a desert ecosystem

Using leaf traits to explain species co-existence and its consequences for primary productivity across a forest-steppe ecotone

Trait-based approaches have been widely applied to uncover the mechanisms determining community assembly and biodiversity-ecosystem functioning relationships. However, they have rarely been used in forest-steppe ecotones. These ecosystems are extremely sensitive to disturbances due to their relatively complex ecosystem structures, functionings and processes. In this study, we selected seven sites along a transect from closed canopy forests (CF) to forest-steppe ecotones (FSE) and meadow steppes (MS) in northeast China. Six leaf functional traits (i.e. leaf nitrogen and phosphorus contents, leaf length and thickness, single leaf area and leaf mass per unit area, LMA) as well as the community composition and aboveground biomass at each site were measured. Both functional trait diversity indices (richness, evenness and divergence) and community-weighted mean trait values (CWMs) were calculated to quantify community trait distributions. We found that dominant species in the FSE communities showed acquisitive strategies with highest leaf nitrogen (Mean ± SE: 19.6 ± 0.5 mg g−1) and single leaf area (19.2 ± 1.3 cm2), but the lowest LMA (59.6 ± 1.3 g cm−2) values compared to adjacent CF and MS communities. The ecotone communities also exhibited the largest functional trait richness (TOP), evenness (TED) and divergence (FDis) values (0.46, 0.92 and 0.67, respectively). Overall, niche differentiation emerges as the main mechanism influencing the coexistence of plant species in ecotone ecosystems. In addition, CWMs of leaf traits were the most important predictors for estimating variations in aboveground productivity across the transect, suggesting a major influence of dominant species. Our findings suggest that vegetation management practices in forest-steppe ecotones should increasingly focus on community functional trait diversity, and support the establishment and regeneration of plant species with rapid resource acquisition strategies.

Litter and root traits control soil microbial composition and enzyme activities in 28 common subtropical tree species

Abstract Plant trait‐based approaches are frequently used to explore the linkages between above‐ground plant communities and below‐ground ecosystem functions. However, the role of plant leaf litter and living root traits in driving soil microbial biomass, community composition and enzyme activities has rarely been explored. Here, we measured the soil microbial biomass, community composition and enzyme activities related to carbon (C), nitrogen (N) and phosphorus (P) acquisition under 3‐year‐old monocultures of 28 common subtropical tree species in China. We found that plant leaf litter and absorptive root traits, including leaf litter C content, litter water holding capacity and root N content, were the three best predictors for soil microbial biomass and enzyme activities. In particular, resource‐exploitative tree species with higher root N contents were associated with microbial communities with lower fungi to bacteria ratios and lower C‐ and P‐acquisition enzyme activities. Tree species with higher leaf litter water holding capacity were associated with microbial resource acquisition strategies for C and P acquisition. Synthesis: Our findings highlighted that plant leaf litter and root traits are important for mechanistically understanding the ecological linkage between the plant community and ecosystem functions.

Soil Compaction Drives an Intra-Genotype Leaf Economics Spectrum in Wine Grapes

Intraspecific trait variation is a critical determinant of ecosystem processes, especially in agroecosystems where single species or genotypes exist in very high abundance. Yet to date, only a small number of studies have evaluated if, how, or why traits forming the Leaf Economics Spectrum (LES) vary within crops, despite such studies informing our understanding of: (1) the environmental factors that drive crop LES trait variation and (2) how domestication has altered LES traits in crops vs. wild plants. We assess intragenotype variation in LES traits in ‘Chardonnay’ (Vitis vinifera)—one of the world’s most commercially important crops—across a soil compaction gradient: one of the most prominent characteristics of agricultural soils that may drive crop trait variation. Our early evidence indicates that ‘Chardonnay’ traits covary along an intragenotype LES in patterns that are qualitatively similar to those observed among wild plants: resource-acquiring vines expressed a combination of high mass-based photosynthesis (Amass), mass-based dark respiration (Rmass), and leaf nitrogen concentrations (N), coupled with low leaf mass per area (LMA); the opposite set of trait values defined the resource-conserving end of the ‘Chardonnay’ LES. Traits reflecting resource acquisition strategies (Amass, Rmass, and leaf N) declined with greater bulk density, while traits related to investment in leaf construction costs (LMA) increased with greater bulk density. Our findings contribute to an understanding of the domestication syndrome in grapevines and also provide information relevant for quantifying trait-based crop responses to environmental change and gradients.

Evergreen and deciduous tree species show distinct strategies to synchronize with seasonality in mid-elevational forests of central Himalaya

Synchronisation of the leaf phenological patterns with favourable environmental conditions and the variations in the leaf traits allow tree species to coexist, support biodiversity and maintain forest productivity with a larger implication on the global carbon cycle. However, within a forest whether plants with contrasting phenological attributes follow similar or distinct adaptive strategies for resource gain in response to seasonality and how they avoid niche-overlap to coexist is less clear. Further, whether the trade-offs between faster leaf growth within a shorter duration and vice-versa as proposed in the worldwide leaf economic spectrum (WLES) holds at the local scale remain inconclusive. Here, we aim to (1) describe patterns of temporal variation in leaf exposure (i.e. initiation, the peak of exposure, longevity, and expansion period) and leaf structural properties (i.e. area, dry mass, specific leaf area, dry-mass lost, construction cost, and mass acquired before the rainy season) among 12 coexisting evergreen and deciduous trees; and (2) explore whether the predictions of the WLES framework hold for evergreen and deciduous mid-elevation trees of the central Himalaya range. Results suggest that with an earlier leaf flush/leaf initiation and faster leaf recruitment in deciduous tree species, these plant species may maximize resource gains while investing less in structural parts of the leaves. In contrast, evergreens exhibit a higher investment in structural traits and retain leaves for a longer period and thereby maximizing resource gains from the growing season. The principal component analysis showed that PC-1 and PC-2 cumulatively explained 68.4% of the total variation in leaf traits. There was a distinct grouping of evergreen and deciduous species along the principal axis-1 for trait variation, suggesting a niche separation, which may allow species to coexist. When tested for the significance of differences in the average values of leaf traits, we found that deciduous trees had higher average values for mass before the rainy season (MRS), dry mass-loss (DML), specific leaf area (SLA), and leaf area (LA) than evergreens. The leaf life span of evergreens was significantly higher compared to the deciduous form which may allow evergreens to pay back the leaf construction cost which on average is higher than deciduous tree species. In a way, deciduous may adopt the resource acquisition strategy while evergreen exhibits a resource conservation strategy. The proposed generalized conservative-acquisitive traits axis of the world leaf economic spectrum thereby holds true for mid-elevational tree species in the central Himalaya.

The impact of platform corporate venture capital vs. traditional corporate venture capital on internet initial public offering underpricing: Evidence from Chinese-listed internet firms

PurposePlatform firms are playing an increasingly major role in venture investment. Based on the motivation perspective and signaling theory, this paper examines the effects of platform corporate venture capital (CVC) versus traditional CVC on Internet IPO underpricing.Design/methodology/approachThe sample consists of 117 Chinese Internet firms that went public between 2004 and 2019. Two-stage Heckman regression analysis was used to test several hypotheses.FindingsThis paper finds that, compared to traditional CVC firms, platform CVC firms increase Internet IPO underpricing. In particular, with the contingency of strong prior performance or implementation of China’s “Internet plus” policy, platform CVC firms increase Internet IPO underpricing more than traditional CVC firms. With increasing Internet penetration, platform CVC firms will increase Internet IPO underpricing less than traditional CVC firms.Practical implicationsAs CVC firms differ in their key resources and motivations used to realize their strategic goals, IPO firms should formulate their resource acquisition strategies according to their resource needs and the contexts in which they operate.Originality/valueBy identifying the differences between platform CVC and traditional CVC, this paper complements previous research on the role of CVC backing of IPOs and extends the knowledge of CVC investment by shedding light on the contingency value of corporate investors and Internet IPO underpricing in emerging markets.

The fern economics spectrum is unaffected by the environment.

The plant economics spectrum describes the trade-off between plant resource acquisition and storage, and sheds light on plant responses to environmental changes. However, the data used to construct the plant economics spectrum comes mainly from seed plants, thereby neglecting vascular non-seed plant lineages such as the ferns. To address this omission, we evaluated whether a fern economics spectrum exists using leaf and root traits of 23 fern species living under three subtropical forest conditions differing in light intensity and nutrient gradients. The fern leaf and root traits were found to be highly correlated and formed a plant economics spectrum. Specific leaf mass and root tissue density were found to be on one side of the spectrum (conservative strategy), whereas photosynthesis rate, specific root area, and specific root length were on the other side of the spectrum (acquisitive strategy). Ferns had higher photosynthesis and respiration rates, and photosynthetic nitrogen-use efficiency under high light conditions and higher specific root area and lower root tissue density in high nutrient environments. However, environmental changes did not significantly affect their resource acquisition strategies. Thus, the plant economics spectrum can be broadened to include ferns, which expands its phylogenetic and ecological implications and utility.

THE EFFECT OF EFFECTUATION PRINCIPLES ON OPPORTUNITY EXPLOITATION BY ENTREPRENEURS IN A DEVELOPING ECONOMY

This study aims to explore the direct effect of effectual means (who I am, who I know, what I have) on the successful exploitation of opportunity by new ventures. Resource acquisition and strategy implementation ability are employed as indicators of opportunity exploitation. We also examine the mediating role of particular, effectual principles on the relationship between effectual means and opportunity exploitation. A total of 462 owners of early-stage small and medium enterprises (SMEs) in Tanzania were surveyed. Structural Equation Modeling (SEM) and hierarchical regression were used to test a set of hypotheses. The results demonstrate that effectual means positively affected both resource acquisition ability and strategy implementation ability. Mediation effects differed based on the type of effectual means and different elements comprising opportunity exploitation. Implications are drawn from the results for theory and practice.

Responses of chlorophyll fluorescence and non-structural carbohydrate accumulation of Castanopsis kawakamii seedlings to seed dispersal positions

When seeds fallen from the mother trees, their initial contact physical environment was litter or soil. The dispersal positions of seeds (seeds positioned on top of the litter, the soil surface and beneath the litter) determine the process of their natural regeneration. We simulated three different dispersal positions of Castanopsis kawakamii, including seeds positioned on top of the litter (2 and 4 cm litter was placed below the seed layer), soil surface (without litter), and seeds beneath the litter (2, 4, 6 and 8 cm litter covers in the upper layer of seeds). We examined the effects of seed dispersal position on the chlorophyll fluorescence characteristics, non-structural carbohydrate, specific leaf area, leaf dry matter content and nutrient content of seedlings. The results showed that leaf nitrogen content per area of seedlings had significantly positive correlation with soluble sugar content, non-structural carbohydrate content, and negative correlation with specific leaf area across different dispersal positions. Seedlings of the moderate litter cover (2 and 4 cm) adopted resource acquisitive strategies by increasing relative chlorophyll content, soluble sugar content, non-structural carbohydrate content, leaf dry matter content, leaf nitrogen content and phosphorus contents per area, and decreasing specific leaf area to achieve their demands for rapid growth. Seedlings grew on soil surface and beneath the deep litter (6 and 8 cm) adopted the resource conservative strategies with higher leaf nitrogen content per mass and specific leaf area, lower leaf dry matter content, and non-structural carbohydrate content to intercept more effective light resources to compensate for the shady environment brought by deep litter. This would further decrease the probability of seedling mortality due to 'carbon starvation'. Seedlings under litter layer stored starch in leaf, and reduced the energy consumption of photosynthetic tissues (low PSⅡ maximum photochemical efficiency) to maintain seedling growth. Comprehensive analysis of entropy method indicated that low amount of litter cover (2 cm) significantly promoted seedling growth of C. kawakamii. In the future, we could regulate the thickness of litter layer to promote the growth and regeneration of C. kawakamii seedlings in natural forest.

Leading nutrient foraging strategies shaping by root system characteristics along the elevations in rubber (Hevea brasiliensis) plantations.

When it comes to root and mycorrhizal associations that define resource acquisition strategy, there is a need to identify the leading dimension across root physiology, morphology, architecture and whole plant biomass allocation to better predict the plant's responses to multiple environmental constraints. Here, we developed a new framework for understanding the variation in roots and symbiotic fungi by quantifying multiple-scale characteristics, ranging from anatomy to the whole plant. We chose the rubber (Hevea brasiliensis) grown at three elevations to test our framework and to identify the key dimensions for resource acquisition. Results showed that the quantities of absorptive roots and root system architecture, rather than single root traits, played the leading role in belowground resource acquisition. As the elevation increased from the low to high elevation, root length growth, productivity and root mass fraction (RMF) increased by 2.9-, 2.3- and 13.8-fold, respectively. The contribution of RMF to the changes in total root length was 3.6-fold that of specific root length (SRL). Root architecture exhibited higher plasticity than anatomy and morphology. Further, mycorrhizal colonization was highly sensitive to rising elevations with a non-monotonic pattern. By contrast, both leaf biomass and specific leaf area (traits) co-varied with increasing elevation. In summary, rubber trees changed root system architecture by allocating more biomass and lowering the reliance on mycorrhizal fungi rather than improving single root efficiency in adapting to high elevation. Our framework is instructive for traits-based ecology; accurate assessments of forest carbon cycling in response to resource gradient should account for the leading dimension of root system architecture.

Microplastics in soil can increase nutrient uptake by wheat

Microplastics can perturb microbial nutrient-mining strategies. However, the mechanism by which microplastics affect the resource-acquisition strategies of crops in agricultural systems remains unknown. The nutrient-acquisition potential of crops and microbes was investigated under treatments with two common microplastics (polyethylene [PE] and polyvinyl chloride [PVC]) at 0%, 1%, and 5% (w/w). Different root resource-acquisition strategies disturbed microbial nutrient turnover in the rhizosphere in response to microplastic addition. Specifically, the β-1,4-glucosidase (BG) hotspot expanded, whereas the rhizosphere expansion of BG activity decreased. A decrease of less than PE1% (w/w) and an expansion of less than PE5% (w/w) in the 1,4-N-acetyl-glucosaminidase (NAG) hotspot with wider rhizosphere expansion of NAG activity indicated that higher doses of PE allow roots to uptake additional N. The phosphomonoesterase (PHOS) hotspot decreased in PE1% (w/w) and expanded in PE5% (w/w), but rhizosphere expansion did not change under PE treatments. However, both NAG and PHOS hotspots expanded with decreasing rhizosphere expansion under PVC treatments, indicating that PVC limits the utilization of available N and P, forcing the crop to obtain nutrients from the narrow root zone. These results indicate that adding PE microplastics increases the demand for and consumption of NH4+-N and NO3--N by wheat.