Patterns Of Resource Acquisition Research Articles

Response of functional traits in Machilus pauhoi to nitrogen addition is influenced by differences of provenances

Comprehensive studies on the response of whole plant functional traits to nitrogen deposition can provide insight into the resource acquisition strategies of plants. However, current studies on nitrogen deposition have mainly focused on leaves or roots.We conducted nitrogen deposition simulation experiments with Machilus pauhoi (Lauraceae) from five provenances in a common garden experiment in the southeast of China. We measured 29 traits (biomass, phenology traits, and nutrient concentrations) of leaves, stems, and roots in response to nitrogen addition and selected 26 distinct important functional traits related to resource acquisition strategies of the whole M. pauhoi seedlings.We found that N (Nitrogen) addition significantly increased the biomass of M. pauhoi seedlings and altered biomass allocation among organs. The response of the leaf, stem and root traits to nitrogen addition was not always consistent among the different provenances of M. pauhoi seedlings. A uniform variation pattern of the three organs was found in the C (Carbon) and P (Phosphorus) concentrations, as well as N:P ratio. In contrast, N concentration, the C:N ratio and the phenotypic trait specific leaf area (SLA) and specific root area (SRL) did not respond in the same direction at the organ level.We concluded that nitrogen addition alters the biomass allocation pattern of M. pauhoi and the resource acquisition capacity of above- and below-ground organs. N concentrations and C:N ratio may play a key role in this regulatory process. Overall, N addition increased leaf mass fraction (LMF) and SRL, and instead decreased SLA and root mass fraction (RMF) of M. pauhoi. There are also differences in biomass allocation and resource acquisition patterns between the different provenances. AF and SC seedlings can be preferred provenances for M. pauhoi due to their balanced resource acquisition strategy and high phenotypic plasticity, respectively.Our study may contribute to a more comprehensive understanding of how N deposition affects the plant as a whole and provide a theoretical basis for precise nutrient management of M. pauhoi seedlings and their plantations in the context of nitrogen deposition.

Institutional stakeholder collaborations (ISCs): a conceptual framework for housing research

Housing development calls for collaboration through a multipronged and concerted effort from all stakeholders to acquire resources within institutional arrangements set by state and local governments. Despite growing attention by UN-Habitat towards the New Urban Agenda for affordable housing, the role of institutional collaboration among stakeholders has been overlooked. For purpose of the present research, a structured literature review was conducted based on 33 papers collaborative archetypes in the affordable housing sector. A typology of key collaborative approaches in housing research and practice is presented jointly to juxtapose these approaches emphasizing the integration of stakeholder engagement with institutional patterns of resource acquisition. The present study offers a conceptual framework of Institutional Stakeholder Collaborations (ISCs) beyond the conventional definitions and concepts of collaboration. The ISCs framework offers a two-level agenda, encouraging scholars and academicians to examine stakeholder engagements and resource dependency patterns within the institutional arrangements for future empirical research, to navigate the affordable housing provision effectively. Finally, this research advances the collaboration theory integrating resource dependence, institutional, and stakeholder theories.

Functional strategies of tropical dry forest plants in relation to growth form and isotopic composition

Tropical dry forests (TDFs) undergo a substantial dry season in which plant species must endure several months of drought. Although TDFs support a diverse array of plant growth forms, it is not clear how they vary in mechanisms for coping with seasonal drought. We measured organic tissue stable isotopic composition of carbon (δ13C) and nitrogen (δ15N) across six plant growth forms including epiphytes, terrestrial succulents, trees, shrubs, herbs, and vines, and oxygen (δ18O) of four growth forms, to distinguish among patterns of resource acquisition and evaluate mechanisms for surviving annual drought in a lowland tropical dry forest in Yucatan, Mexico. Terrestrial succulent and epiphyte δ13C was around –14‰, indicating photosynthesis through the Crassulacean acid metabolism pathway, and along with one C4 herb were distinct from mean values of all other growth forms, which were between –26 and –29‰ indicating C3 photosynthesis. Mean tissue δ15N across epiphytes was –4.95‰ and was significantly lower than all other growth forms, which had values around +3‰. Tissue N concentration varied significantly among growth forms with epiphytes and terrestrial succulents having significantly lower values of about 1% compared to trees, shrubs, herbs and vines, which were around 3%. Tissue C concentration was highest in trees, shrubs and vines, intermediate in herbs and epiphytes and lowest in terrestrial succulents. δ18O did not vary among growth forms. Overall, our results suggest several water-saving aspects of resource acquisition, including the absolute occurrence of CAM photosynthesis in terrestrial succulents and epiphytes, high concentrations of leaf N in some species, which may facilitate CO2 drawdown by photosynthetic enzymes for a given stomatal conductance, and potentially diverse N sources ranging from atmospheric N in epiphytes with extremely depleted δ15N values, and a large range of δ15N values among trees, many of which are legumes and dry season deciduous.

Effects of clump spacing on nutrient distribution and root activity of Dendrocalamus strictus in the humid region of Kerala, peninsular India

The humid agroclimatic conditions of Kerala, India permit the cultivation of an array of bamboo species of which Dendrocalamus strictus Roxb. (Nees.) is an important one on account of its high growth rate and multiple uses. Stand density, a potential tool in controlling the productivity of woody ecosystems, its effect on growth and root distribution patterns may provide a better understanding of productivity optimization especially when bamboo-based intercropping options are considered. Growth attributes of 7-year-old bamboo (D. strictus) stands managed at variable spacing (4 × 4 m, 6 × 6 m, 8 × 8 m, 10 × 10 m, 12 × 12 m) were studied. Functional root activity among bamboo clumps were also studied using a radio tracer soil injection method in which the radio isotope 32P was applied to soil at varying depths and lateral distances from the clump. Results indicate that spacing exerts a profound influence on growth of bamboo. Widely spaced bamboo exhibited higher clump diameters and crown widths while clump heights were better under closer spacing. Clump height was 30% lower and DBH 52% higher at the widest spacing (12 × 12 m) compared to the closest spacing (4 × 4 m). With increasing soil depth and lateral distance, root activity decreased significantly. Root activity near the clump base was highest (809 counts per minute, cpm; 50 cm depth and 50 cm lateral distance) at 4 × 4 m. Tracer study further showed wider distribution of root activity with increase in clump spacing. It may be concluded that the intensive foraging zone of bamboo is within a 50-cm radius around the clump irrespective of spacing. N, P and K content in the upper 20 cm was 2197, 21, and 203 kg/ha respectively for the closely spaced bamboo (4 × 4 m) which were significantly higher than corresponding nutrient content at wider spacings. About 50% of N, P and K were present within the 0–20 cm soil layer, which decreased drastically beyond the 20 cm depth. The results suggest that stand management practices through planting density regulation can modify the resource acquisition patterns of D. strictus which in turn can change growth and productivity considerably. Such information on root activities, spatial and temporal strategies of resource sharing will be helpful in deciding the effective nutrition zone for D. strictus. Further, the study throws light on the spatial distribution of non-competitive zones for productivity optimization yields, especially when intercropping practices are considered.

Global resource acquisition patterns of invasive and native plant species do not hold at the regional scale in Mediterranean type ecosystems

Invasive species may outperform native species by acquiring more resources or by efficiently using limited resources. Studies comparing leaf traits as a metric of carbon capture strategies in native and invasive species have come to different conclusions. Some studies suggest that invasive species are better at acquiring resources, but that native and invasive species use resources similarly. Other studies have found that native and invasive species differ in resource use efficiency, which implies different biochemical or physiological mechanisms of carbon capture. To resolve this debate, we examined relationships among four leaf traits (photosynthetic rate, specific leaf area, foliar nitrogen, foliar phosphorus) in co-occurring native and invasive species from eight plant communities across five Mediterranean-climate ecosystems. We performed standardized major axis regression for all trait combinations within and across sites, testing for slope homogeneity and shifts in elevation (y-intercept) or along a common slope between species groups. Across the global dataset, native and invasive species had similar carbon capture strategies (i.e., similar slopes), with invasive species occupying a position of greater resource acquisition. However, these patterns did not hold when regions were analyzed individually. Regional differences may be driven by differences in life form between native and invasive species, and variation in soil resource availability among regions. Our context-dependent results reveal not only that management of invasive species will differ across regions but also that global comparisons of invasive and native species can be misleading.

The total opportunity for sexual selection and the integration of pre- and post-mating episodes of sexual selection in a complex world.

It is well known that sexual selection can target reproductive traits during successive pre- and post-mating episodes of selection. A key focus of recent studies has been to understand and quantify how these episodes of sexual selection interact to determine overall variance in reproductive success. In this article, we review empirical developments in this field but also highlight the considerable variability in patterns of pre- and post-mating sexual selection, attributable to variation in patterns of resource acquisition and allocation, ecological and social factors, genotype-by-environment interaction and possible methodological factors that might obscure such patterns. Our aim is to highlight how (co)variances in pre- and post-mating sexually selected traits can be sensitive to changes in a range of ecological and environmental variables. We argue that failure to capture this variation when quantifying the opportunity for sexual selection may lead to erroneous conclusions about the strength, direction or form of sexual selection operating on pre- and post-mating traits. Overall, we advocate for approaches that combine measures of pre- and post-mating selection across contrasting environmental or ecological gradients to better understand the dynamics of sexual selection in polyandrous species. We also discuss some directions for future research in this area.

Who Shall Get More? How Intangible Assets and Aspiration Levels Affect the Valuation of Resources

Combining findings from the research streams on intangible assets and problemistic search, we develop a framework to explain the valuation of resources by organizations. Similar to search behavior and resource acquisition patterns, we expect organizations to value resources more as they encounter problems those resources can help solve. We study this by considering two intangible assets, reputation and status, brought by resource providers to organizations, and two outcomes, product quality and revenues. Building on recent research that has found reputation to be more closely tied to product quality, and status to be more closely tied to revenues, we expect organizations to value resource providers possessing an intangible asset more as they encounter performance problems on the outcome more closely tied to that particular asset. Furthermore, we also expect this sensitivity to manifest itself primarily when the organization has a low stock of the particular intangible asset they are in need of. We find support for our hypotheses in a sample of NBA players and teams.

Functional composition controls invasion success in a California serpentine grassland

Summary 1. Recent debates about the role of biotic resistance in controlling invasion success have focused on effects of species richness. However, functional composition could be a stronger control: species already in the community with similar functional traits to those of the invaders should have the greatest competitive effect on invaders. Still, experiments assessing effects of functional similarity have found contradictory results. 2. We used experimental communities in a serpentine grassland in California, USA, to assess the extent to which functional composition and functional diversity influenced success of two different types of invading plants: early season annuals (E) and late‐season annuals (L) that have been previously shown to differ in patterns of resource acquisition. 3. We seeded known quantities of seed of six different species (three in each functional group) into experimental plots containing established communities differing in functional composition and functional diversity. The experimental communities contained different combinations of E, L, perennial bunchgrass (P) and nitrogen‐fixer (N) functional groups, with functional diversity ranging from 0 to 4 groups. Each invading species was seeded into a separate quadrat within each plot to minimize competitive effects of invaders on each other. We measured both seedling and adult success of invaders for two full growing seasons to further understand mechanisms underlying biotic resistance. 4. More functionally diverse communities were less invaded overall, as measured by the average success of individual invaders. However, assessment of invaders by functional groups was more informative: Es in the extant community suppressed E invaders the most, and Ls in the extant community suppressed L invaders the most. 5. We observed a variety of interactions among extant functional groups in reducing invader success, including synergism, complementarity and ‘basement’ effects, where two or more groups negatively affected invaders, but combinations of groups were no more suppressive than single groups. The extant community influenced invaders more strongly through suppression of adult plant growth than through effects on seedling establishment. 6. Synthesis. Contrary to predictions from neutral theory, these results indicate that niche overlap was an important component of biotic resistance in these experimental plant communities and summed up to significant effects of species richness.

Precipitation pulse use by an invasive woody legume: the role of soil texture and pulse size

Plant metabolic activity in arid and semi-arid environments is largely tied to episodic precipitation events or "pulses". The ability of plants to take up and utilize rain pulses during the growing season in these water-limited ecosystems is determined in part by pulse timing, intensity and amount, and by hydrological properties of the soil that translate precipitation into plant-available soil moisture. We assessed the sensitivity of an invasive woody plant, velvet mesquite (Prosopis velutina Woot.), to large (35 mm) and small (10 mm) isotopically labeled irrigation pulses on two contrasting soil textures (sandy-loam vs. loamy-clay) in semi-desert grassland in southeastern Arizona, USA. Predawn leaf water potential (psi(pd)), the isotopic abundance of deuterium in stem water (deltaD), the abundance of 13C in soluble leaf sugar (delta13C), and percent volumetric soil water content (theta(v)) were measured prior to irrigation and repeatedly for 2 weeks following irrigation. Plant water potential and the percent of pulse water present in the stem xylem indicated that although mesquite trees on both coarse- and fine-textured soils quickly responded to the large irrigation pulse, the magnitude and duration of this response substantially differed between soil textures. After reaching a maximum 4 days after the irrigation, the fraction of pulse water in stem xylem decreased more rapidly on the loamy-clay soil than the sandy-loam soil. Similarly, on both soil textures mesquite significantly responded to the 10-mm pulse. However, the magnitude of this response was substantially greater for mesquite on the sandy-loam soil compared to loamy-clay soil. The relationship between psi(pd) and delta13C of leaf-soluble carbohydrates over the pulse period did not differ between plants at the two sites, indicating that differences in photosynthetic response of mesquite trees to the moisture pulses was a function of soil water availability within the rooting zone rather than differences in plant biochemical or physiological constraints. Patterns of resource acquisition by mesquite during the dynamic wetting-drying cycle following rainfall pulses is controlled by a complex interaction between pulse size and soil hydraulic properties. A better understanding of how this interaction affects plant water availability and photosynthetic response is needed to predict how grassland structure and function will respond to climate change.

Constancy of the G matrix in ecological time.

The constancy of the genetic variance-covariance matrix (G matrix) across environments and populations has been discussed and tested empirically over the years but no consensus has so far been reached. In this paper, I present a model in which morphological traits develop hierarchically, and individuals differ in their resource allocation and acquisition patterns. If the variance in resource acquisition is many times larger than the variance in resource allocation then strong genetic correlations are expected, and with almost isometric relations among traits. As the variation in resource acquisition decreases below a certain threshold, the correlations decrease overall and the relations among traits become a function of the allocation patterns, and in particular reflecting the basal division of allocation. A strong bottleneck can break a pattern of strong genetic correlation, but this effect diminishes rapidly with increasing bottleneck size. This model helps to understand why some populations change their genetic correlations in different environments, whereas others do not, since the key factor is the relation between the variances in resource acquisition and allocation. If a change in environment does not lead to a change in this ratio, no change can be expected, whereas if the ratio is changed substantially then major changes can be expected. This model can also help to understand the constancy of morphological patterns within larger taxa as a function of constancy in resource acquisition patterns over time and environments. When this pattern breaks, for example on islands, larger changes can be expected.

A comparison of ecological responses among aclonal (unitary), clonal and coalescing macroalgae

Based on growth patterns, regeneration capabilities and genetic make up, benthic macroalgae include three groups of species. Similar to land plants, they include clonal and aclonal species, and, similar to colonial aquatic animals, seaweeds also include coalescing species, that have the capacity to fuse forming composite (chimeric) entities. Since the awareness of the differences between these three kinds of seaweeds is rather recent, most ecological studies have not discriminated among them. However, ecological models based on one kind of seaweeds will not necessarily apply to all kinds of seaweeds. This study reviews ecological responses of algae at the individual and community levels, and describes similarities and differences among both the three algal groups and with parallel groups in land plants and chimeric marine animals. The ecological responses reviewed are plant sizes and shapes; patterns of resource acquisition; algal life phases, reproduction and dispersal; genetic variability, intraspecific and interspecific competition and herbivory. Analysis of these responses supports the idea in distinguishing among the above three algal group, reveals the need for numerous additional ecological studies and advices on incorporating concepts from the biology of chimeric aquatic animals and from clonal theory of land plants into the study of benthic macroalgae.

CONSTANCY OF THE G MATRIX IN ECOLOGICAL TIME

The constancy of the genetic variance-covariance matrix (G matrix) across environments and populations has been discussed and tested empirically over the years but no consensus has so far been reached. In this paper, I present a model in which morphological traits develop hierarchically, and individuals differ in their resource allocation and acquisition patterns. If the variance in resource acquisition is many times larger than the variance in resource allocation then strong genetic correlations are expected, and with almost isometric relations among traits. As the variation in resource acquisition decreases below a certain threshold, the correlations decrease overall and the relations among traits become a function of the allocation patterns, and in particular reflecting the basal division of allocation. A strong bottleneck can break a pattern of strong genetic correlation, but this effect diminishes rapidly with increasing bottleneck size. This model helps to understand why some populations change their genetic correlations in different environments, whereas others do not, since the key factor is the relation between the variances in resource acquisition and allocation. If a change in environment does not lead to a change in this ratio, no change can be expected, whereas if the ratio is changed substantially then major changes can be expected. This model can also help to understand the constancy of morphological patterns within larger taxa as a function of constancy in resource acquisition patterns over time and environments. When this pattern breaks, for example on islands, larger changes can be expected.

Ecophysiological consequences of contrasting microenvironments on the desiccation tolerant moss Tortula ruralis.

Tortula ruralis is a homoiochlorophyllous-desiccation-tolerant (HDT) moss that retains all pigments when dehydrated and rapidly recovers physiological function upon rehydration. This moss forms extensive cover in exposed and shaded areas in the sandy semi-arid grasslands of Central Europe. We hypothesized that contrasting drying regimes between these microhabitats would affect plant N status, constraints to gas exchange and growth, as well as result in altered pigment concentrations and ratios, and photochemical light-response dynamics. Furthermore, we believed T. ruralis's HDT habit would limit its ability to acclimate to altered light environment. We found that sun plant T. ruralis had lower plant mass, as well as lower tissue N, C, total photosynthetic pigment concentrations and carbon isotope discrimination (Δ) values compared to shade plant counterparts. Carotenoid/chlorophyll ratios in sun plants were typical of high light-adapted tissue, but chlorophyll a/chlorophyll b ratios were lower, more characteristic of low light-adapted tissue. This unique combination of pigment responses was accompanied by sustained lower levels of optimal quantum efficiency of PSII (F v/F m) in sun plant T. ruralis, even during favorable diurnal conditions, and reduced engagement of energy-dependent thermal dissipation (NPQ). Reciprocal transplants of sun and shade plants showed that T. ruralis is capable of short-term adjustment to altered light level, as evidenced by increases in F v/F m, NPQ, and light-adapted PSII yield (φPSII) in transplanted sun plants, and concurrent decreases in sun-transplanted shade plants. However, the performance of transplanted sun plants remained consistently below that of undisturbed shade plants. These findings show that microenvironmental variation results in different patterns of resource acquisition in this HDT moss, and that growth in the open imparts greater desiccation tolerance, and the development of a greater standing engagement of slowly reversing photoprotective mechanisms. In contrast, prolonged activity and greater resource acquisition in shaded populations may allow T. ruralis to rapidly adjust to changes following disturbance to the plant canopy, fostering the persistence of T. ruralis in these semi-arid grasslands.

Diallel crosses reveal patterns of variation in fruit-set, seed mass, and seed number in Asclepias incarnata.

Plants from each of two populations of Asclepias incarnata ssp. incarnata were hand-pollinated in diallel crosses and seed number per fruit, mean individual seed mass per fruit and fruit-set were determined for the parental plants. Two diallels were performed on the glasshouse-grown plants, one involving six plants from one population and the other involving five plants from the second population. The contributions to total phenotypic variation from joint, maternal, paternal, and two types of interaction sources of variation were then estimated. Variance attributable to maternal effects, reflecting differences between maternal plants resulting from environmental or genetic factors or both, comprised 31.3-68.4% of total variance in seed mass, 20.5-37.1% of variance in seed number, and 0.7-7.5% of variance in fruit-set. Interaction effects that depended on the direction of the cross accounted for 7.3-46.5% of variance in seed mass and 31.4-39.1% of variance in seed number. These interaction effects are consistent with the hypothesis that maternal plants provision resources differently to seeds depending on the specific genotypes of the embryos they contain. In the analysis of fruit-set, interaction effects independent of the direction of the cross (combined variance) explained 22.9-78.0% of phenotypic variance. These effects could have several causes, including inbreeding depression, shared incompatibility alleles, or 'control' of fruit-set by zygotes via hormonal signals or patterns of resource acquisition.

Growth and dry matter partitioning in loblolly and ponderosa pine seedlings in response to carbon and nitrogen availability

summaryWe grew loblolly pine (Pinus taeda L.) and ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings in a factorial experiment with two CO2 partial pressures (35 and 70 Pa) and two nitrogen treatments (1‐0 and 3–5 mM NH4+) for one growing season in a ‘common garden’ experiment designed to examine the extent that dry matter and nitrogen accumulation and partitioning are environmentally controlled. Ponderosa pine seedlings grown in 35 Pa CO2 and 3.5 mM NH4+ showed symptoms of nitrogen toxicity, characterized by greatly reduced growth, and moderately reduced total plant N. With the exception of this treatment combination, there were no significant differences between species in total plant dry matter or total plant nitrogen, suggesting that responses of growth to environmental conditions were stronger than heritable responses. There were however large differences in dry matter and N partitioning between the two species. Increases in leaf mass were largest in loblolly pine, whilst ponderosa pine tended to have higher root: shoot (R:S) ratios. R:S ratio of loblolly increased in response to C availability and decreased in response to N availability, whilst R: S ratio of ponderosa pine was much less responsive to resource availability. Total plant N varied with N supply, and N partitioning was related to plant growth and carbon partitioning. Carbon and N were interactive, such that an increase in the accumulation of either resource was always accompanied by an increase in the other. Over several seasons the different patterns of resource acquisition and biomass allocation that we observed in a uniform environment could potentially result in different growth rates at most resource levels. In the first season, contrary to our expectations, heritable differences in growth rate did not appear.

Resource allocation by plants under air pollution stress: Implications for plant-pest-pathogen interactions

Plant growth depends on the coordinated acquisition and allocation of carbon, water, and nutrient resources to the major plant organs (root, stem, leaf, flower, and fruit) and to the major classes of metabolic function (vegetative growth, maintenance, defense, and reproduction). Air pollutants like SO2, NO2, and O3 can directly damage plant tissues and disrupt normal patterns of resource acquisition and allocation. These disruptions in turn potentially will influence the plant’s ability to defend itself against pests and pathogens. This review summarizes the quantitative and qualitative changes that have been observed when plants are exposed to low levels of SO2, NO2, and O3; the following generalizations emerge: 1. Root biomass is reduced more than shoot biomass in plants exposed to SO2 or O3, but NO2 does not appear to induce the differential suppression of above-versus below-ground organs. 2. Quantitative allocation to leaves increases and to stem decreases under SO2 pollution regimes; too few data are available to generalize about O3 or NO2 effects on leaf: stem ratio. 3. Root carbohydrate concentrations sometimes increase and sometimes decrease after SO2 or O3 fumigations. Leaf nitrogen concentrations tend to decrease after exposure to air pollutants, and leaf carbohydrate concentrations can increase or decrease. Too few data on leaf concentrations of lipids and secondary chemicals are available to justify any generalizations on pollutant responses. 4. Reproduction is suppressed by O3, SO2, and NO2, with O3 appearing to have the most marked effects. Seed lipid and protein composition can be altered by exposure to pollutants. While both quantitative and qualitative changes in plant resource allocation after exposure to pollutants are common, the importance of these diverse changes for plant-pest and plant-pathogen interaction requires more comprehensive study. Ideally, the time course of plant growth and of metabolite pools critical to particular pests or pathogens should be followed in plants exposed to realistic pollutant regimes and related to pest or pathogen performance on the treated plants.