scholarly journals Accounting for underlying complexities identifies simple hierarchy of trait‒environment relationships in Wisconsin forest understory communities

2020 ◽  
Author(s):  
Andrés G. Rolhauser ◽  
Donald M. Waller ◽  
Caroline M. Tucker
Keyword(s):  
Observational Data ◽  
Plant Height ◽  
Mixed Model ◽  
Environmental Gradients ◽  
Functional Structure ◽  
Forest Understory ◽  
Weighted Mean ◽  
Community Weighted Mean ◽  
Understory Communities ◽  
Positive Effect

AbstractAdaptive relationships between traits and the environment are often inferred from observational data by regressing community-weighted mean (CWM) traits on environmental gradients. However, trait‒environment relationships are better understood as the outcome of trait‒abundance and environment‒abundance relationships, and the interaction between traits and the environment. Accounting for this functional structure and for interrelationships among traits should improve our ability to accurately describe general trait‒environment relationships. Using forest understory communities in Wisconsin, we applied a generalized mixed model (GLMM) incorporating this structure. We identified a simple hierarchy of trait‒environment relationships dominated by a strong positive effect of mean temperature on plant height. Compared to the traditional CWM approach, the GLMM was more conservative in identifying significant trait‒environment relationships, and also detected important relationships that CWM regressions overlooked. This work highlights the need to consider the complexity underlying trait‒environment relationships in future analyses.

scholarly journals Accounting for underlying complexities identifies simple hierarchy of trait‒environment relationships in Wisconsin forest understory communities

2020 ◽  
Author(s):  
Andres Rolhauser ◽  
Don Waller ◽  
Caroline Tucker
Keyword(s):  
Observational Data ◽  
Plant Height ◽  
Mixed Model ◽  
Environmental Gradients ◽  
Functional Structure ◽  
Forest Understory ◽  
Weighted Mean ◽  
Community Weighted Mean ◽  
Understory Communities ◽  
Positive Effect

Adaptive relationships between traits and the environment are often inferred from observational data by regressing community-weighted mean (CWM) traits on environmental gradients. However, trait‒environment relationships are better understood as the outcome of trait‒abundance and environment‒abundance relationships, and the interaction between traits and the environment. Accounting for this functional structure and for interrelationships among traits should improve our ability to accurately describe general trait‒environment relationships. Using forest understory communities in Wisconsin, we applied a generalized mixed model (GLMM) incorporating this structure. We identified a simple hierarchy of trait‒environment relationships dominated by a strong positive effect of mean temperature on plant height. Compared to the traditional CWM approach, the GLMM was more conservative in identifying significant trait‒environment relationships, and also detected important relationships that CWM regressions overlooked. This work highlights the need to consider the complexity underlying trait‒environment relationships in future analyses

Explaining variation in productivity requires intraspecific variability in plant height among communities

2021 ◽  
Author(s):  
Li Zhang ◽  
Xiang Liu ◽  
Shurong Zhou ◽  
Bill Shipley
Keyword(s):  
Plant Height ◽  
Structural Equation ◽  
Functional Group ◽  
Intraspecific Variability ◽  
Ecosystem Functions ◽  
Weighted Mean ◽  
Interspecific Variability ◽  
Community Weighted Mean ◽  
Intraspecific Trait Variability ◽  
Trait Variability

Abstract Aims While recent studies have shown the importance of intraspecific trait variation in the processes of community assembly, we still know little about the contributions of intraspecific trait variability to ecosystem functions. Methods Here, we conducted a functional group removal experiment in an alpine meadow in Qinghai-Tibetan Plateau over four years to investigate the relative importance of inter- and intra-specific variability in plant height for productivity. We split total variability in plant height within each of 75 manipulated communities into interspecific variability (TVinter) and intraspecific variability within a community (ITVwithin). Community weighted mean height among communities was decomposed into fixed community weighted mean (CWMfixed) and intraspecific variability among communities (ITVamong). We constructed a series of generalized additive mixed models and piecewise structural equation modelling to determine how trait variability (i.e., TVinter, ITVwithin, CWMfixed and ITVamong) indirectly mediated the changes in productivity in response to functional group removal. Important Findings Community productivity was not only affected directly by treatment manipulations, but also increased with both inter- and intra-specific variability (i.e., CWMfixed, ITVamong) in plant height indirectly. This suggests that both the “selection effect” and a “shade-avoidance syndrome” can incur higher CWMfixed and ITVamong, and may simultaneously operate to regulate productivity. Our findings provide new evidence that, besides interspecific variability, intraspecific trait variability in plant height also plays a role in maintaining net primary productivity.

scholarly journals Effect of Fertilization with Urea and Inhibitors on Growth, Yield and CBD Concentration of Hemp (Cannabis sativa L.)

2021 ◽  
Vol 13 (4) ◽  
pp. 2157
Author(s):  
Ioanna Kakabouki ◽  
Angeliki Kousta ◽  
Antigolena Folina ◽  
Stella Karydogianni ◽  
Charikleia Zisi ◽  
...  
Keyword(s):  
Plant Height ◽  
Field Experiments ◽  
Cannabis Sativa ◽  
Nitrification Inhibitor ◽  
Growth Yield ◽  
Urease Inhibitor ◽  
Significance Level ◽  
Yield And Quality ◽  
Positive Effect ◽  
Urea Fertilization

Field experiments were conducted during 2019 in two different locations in Greece (Athens and Farsala) to evaluate the effect of urea and urea fertilization with inhibitors on the agronomic yield and quality characteristics of two cannabis varieties (Cannabis sativa L.), “Uso31”and “Fedora 17”. The experimental design was split-plot with four different fertilization treatments—control, Urea (U), urea with Urease Inhibitor (UI), and urea with Nitrification Inhibitor (NI) and urease inhibitor (UI). The significance of differences between treatments was estimated by using Tukey’s test with a significance level of p = 0.05. The plant height was significantly affected by the different fertilizations and different varieties as well as by the two locations. The maximum plant height was 197 cm for “Fedora 17”in Farsala. The seed yield was higher forthe urea with inhibitors treatment in both varieties. The Cannabidiol (CBD) content was significantly affected by the fertilization—it was higher in urea with inhibitors in “Uso31”and “Fedora 17” treatments. The lowest CBD content value was 1.29% (control) and the highest was 1.69% (urea NI + UI). In conclusion, in both varieties, it seems that urea with inhibitors has a positive effect on their growth, as well as on the increase in cannabidiol (CBD) content.

scholarly journals Disturbance intensity, disturbance extent and ocean climate modulate kelp forest understory communities

2020 ◽  
Vol 651 ◽  
pp. 57-69
Author(s):  
T Wernberg ◽  
M Couraudon-Réale ◽  
F Tuya ◽  
M Thomsen
Keyword(s):  
Functional Groups ◽  
Kelp Forest ◽  
Forest Understory ◽  
Small Scale ◽  
Kelp Forests ◽  
Ocean Climate ◽  
Disturbance Regimes ◽  
Disturbance Intensity ◽  
Control Community ◽  
Understory Communities

Disturbances often control community structure by removing large dominant species, allowing new species to colonize. Disturbances vary in intensity and extent, and their effects on resident communities can depend on local environmental conditions. We tested the effects of disturbance intensity and extent on different functional groups of understory species in kelp forests at 4 locations along an ocean climate gradient in Western Australia. We hypothesized that, compared to intact canopies, increasing disturbance intensities (50 and 100% of kelp removal) and extents (2, 4 and 8 m diameter) would promote light-dependent competitors (turf, foliose, articulated coralline and fucoid seaweeds) at the expense of less light-dependent functional groups (invertebrates and encrusting seaweeds). We also hypothesized that these effects would be most pronounced at warmer relative to cooler locations, where metabolic and ecological rates are faster. The first hypothesis was supported; light-dependent understory groups (turfs, in particular) increased, while less light-dependent groups (crusts in particular) decreased with increasing disturbance regimes. However, the second hypothesis was not supported; even though understory communities differed between locations and turf covers were highest at the warmest location, we found no significant interactions between locations and disturbance regimes. Importantly, our results revealed that even small-scale partial canopy loss can have significant effects on kelp-associated communities. The implied community-wide, density-dependent effects have implications for the management and conservation of kelp forests, because restoration of ecological functions must also consider the density of kelp forests, not simply their presence or absence.

scholarly journals The legacy of deer overabundance: long-term delays in herbaceous understory recovery

2016 ◽  
Vol 46 (3) ◽  
pp. 362-369 ◽  
Author(s):  
Thomas H. Pendergast ◽  
Shane M. Hanlon ◽  
Zachary M. Long ◽  
Alejandro A. Royo ◽  
Walter P. Carson
Keyword(s):  
Community Composition ◽  
Community Response ◽  
Forest Understory ◽  
Total Density ◽  
Eastern United States ◽  
Legacy Effect ◽  
Browse Species ◽  
Understory Communities ◽  
Open Question ◽  
And Control

Decades of white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) overpopulation have dramatically homogenized forests across much of the eastern United States, creating depauperate forest understory communities. The rate at which these communities recover once deer browsing has been reduced remains an open question. We evaluate overbrowsing legacy effects by examining how forest herbaceous layers respond in terms of biodiversity, density, and community composition over 11 years using exclosures and control plots within a mature beech–maple forest. Although little recovery occurred in the first 5 years, total density and preferred browse density rebounded substantially during the final years of the study. Although community composition began to diverge between exclosure and control plots after 5 years, diversity failed to recover even after 11 years of excluding browsers. Our findings show that vulnerable species can increase after excluding browsers but only if those species were initially present. Biodiversity recovery may be extremely slow because preferred browse species have been nearly extirpated from many forests and thus are unable to recruit into refugia. We empirically demonstrate the extent of the ghost of herbivory past or legacy effect of browsing, i.e., the substantial time delay between herbivore abatement and community response after decades of high deer densities.

The demography of a dominant Amazon liana species exhibits little environmental sensitivity

2015 ◽  
Vol 32 (1) ◽  
pp. 79-82 ◽  
Author(s):  
Luciana de Campos Franci ◽  
Jens-Christian Svenning ◽  
Henrik Balslev ◽  
Fernando Roberto Martins ◽  
Jacob Nabe-Nielsen
Keyword(s):  
Dominant Species ◽  
Environmental Gradients ◽  
Floristic Composition ◽  
Environmental Variation ◽  
Common Species ◽  
Amazon Forest ◽  
Vegetation Density ◽  
Vital Rates ◽  
Relative Growth ◽  
Positive Effect

Abstract:Despite its high plant diversity, the Amazon forest is dominated by a limited number of highly abundant, oligarchic tree and liana species. The high diversity can be related to specific habitat requirements in many of the less common species, but fewer studies have investigated the characteristics of the dominant species. To test how environmental variation may contribute to the success of dominant species we investigated whether the vital rates of the abundant liana Machaerium cuspidatum is sensitive to canopy height, topographic steepness, vegetation density, soil components and floristic composition across an Ecuadorian Amazon forest. The population was inventoried in 1998 and in 2009. Plants were divided into seedling-sized individuals, non-climbers and climbers. Out of 448 seedling-sized plants 421 died, 539 of 732 non-climbers died, and 107 of 198 climbers died. There was weak positive effect of dense understorey on the relative growth rate of climbers. The mortality of seedling-sized plants was higher in areas with intermediate slope, but for larger plants mortality was not related to environmental variation. The limited sensitivity of the vital rates to environmental gradients in the area suggests that ecological generalism contributes to the success of this dominant Amazonian liana.

Effect of laser priming on canola yield and its components under salt stress

2012 ◽  
Vol 26 (1) ◽  
pp. 45-51 ◽  
Author(s):  
S. Mohammadi ◽  
F. Shekari ◽  
R. Fotovat ◽  
A. Darudi
Keyword(s):  
Salt Stress ◽  
Plant Height ◽  
Correlation Coefficients ◽  
Yield Increase ◽  
Effect On Yield ◽  
Lateral Branches ◽  
Pod Length ◽  
Positive Effect ◽  
Pod Number ◽  
Number Of Seeds

Effect of laser priming on canola yield and its components under salt stressThe effect of laser priming at different irradiation times on canola yield and its components under saline conditions were investigated. The results showed that laser priming had a positive effect on yield and its components and caused yield increase under saline conditions. Increase in salt levels had a negative and significant effect on seed yield, number of seeds per pod, number of pod per plant, pod length and plant height. The results showed that 45-min laser priming had the strongest effect on yield and yield components and reduced significantly the adverse effects of salinity. By contrast, laser radiation applied for 60 and 75 min, resulted in a dramatic decrease in yield and its components. Correlation coefficients between the attributes showed that canola yield had a positive and significant correlation with plant height, number of seeds, pod per main branch and lateral branches, length of pod and number of lateral branches. Effects of laser and salinity were significant on lateral branch pod length but not on main branch pods.

scholarly journals Comparing Correlation Coefficients and Path Analysis in Different Populations of Rice (Oryza sativa L.)

2020 ◽  
pp. 1-11
Author(s):  
Anjani Kumar ◽  
D. N. Singh ◽  
Krishna Prasad ◽  
Avinash Pandey
Keyword(s):  
Path Analysis ◽  
Plant Height ◽  
Harvest Index ◽  
Oryza Sativa L ◽  
Grain Weight ◽  
Path Coefficient ◽  
Panicle Length ◽  
Biomass Harvest ◽  
Different Populations ◽  
Positive Effect

This study performed to determine the correlation, their comparison and path coefficients of yield and yield contributing characters by using F2 (BPT-5204 /IR-64Drt1) their two parents separately and the joint parental populations. In this study, the computations for testing the significance of the difference between the 15 traits of different populations of rice determined from 324 F2, 9 IR-64Drt1 (P1), 9 BPT-5204 (P2) and 18 joint parental population. Results showed that the correlation of F2 indicated that the number of total tillers per plant, number of panicles per plant, plant height, panicle length, biomass, harvest index and yield per panicle were positive and significant association with yield per plant. Correlation of IR-64Drt1 stated that the plant height, panicle length, biomass and harvest index were positive and significant association with yield per plant. Correlation of BPT-5204 shown that the secondary branches per panicle and hundred-grain weight exhibited positive and significant association with yield per panicle. Correlation of the joint parent indicated that the plant height, panicle length, grain length, grain width, hundred-grain weight, biomass, harvest index and yield per panicle had exhibited positive and significant association with yield per plant. Path coefficient analysis indicated that harvest index had the highest direct positive effect (0.582) on yield per plant in the F2 population. However, the panicles per plant had the highest direct positive effect (1.481) on yield per plant IR-64Drt1 population. The total tillers per plant had the highest direct positive effect (1.821) on yield per plant in BPT-5204 population. In the joint population of BPT-5204 and IR-64Drt1, path analysis of yield components revealed that the biomass had the highest direct positive effect (0.658) on yield per plant. Information obtained in this study revealed that traits, the harvest index, biomass and panicles per plant are suggested as selection indices for grain yield improvement at segregating populations of rice.

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