Strong Positive Direct Effect Research Articles

Functional richness mediates landscape and management effects on tree biomass and soil fertility during secondary forest succession

Secondary forests can play a critical role in conserving plant biodiversity and sequestering carbon. However, intensive past management, fragmentation, and initial soil fertility can hinder forest recovery during secondary succession, especially in terms of tree species selection. In turn, tree species selection can negatively impact soil fertility recovery and may slow down the succession process, but the direct and indirect effects between these factors remain unclear. To assess the complex interactions among landscape, previous management, soil and vegetation, 27 secondary forests of varying ages, previously used for eucalyptus plantations, located in diverse landscape configurations within the Atlantic Forest biome, were examined. Key variables, such as planting frequency, cutting frequency, forest cover in the landscape, patch isolation between fragments, functional richness, tree aboveground biomass (AGB), soil sum of bases, soil organic matter, and soil phosphorus concentration were used to construct a structural equation model to evaluate the direct and indirect effects of landscape and previous management on forest development. Cutting frequency and patch isolation had a negative direct effect on functional richness. Additionally, a strong positive direct effect of functional diversity on aboveground biomass and soil sum of bases was found. Thus, cutting frequency and patch isolation had negative indirect effects on biomass and soil sum of bases (a proxy for soil fertility), mediated by functional richness. These findings underscore the significance of integrating plant functional diversity into restoration strategies to preserve ecosystem functioning and efficiently recover biodiversity, tree biomass, and soil fertility in secondary forests.

Study on Correlation and Path Analysis in Forage Sorghum [Sorghum bicolor (L.) Moench

This investigation is conducted to determine character association and path coefficient analysis using 35 genotypes of forage sorghum at the Crop Research Centre of the Sardar Vallabhbhai Patel University of Agriculture and Technology in Meerut. In Kharif 2022, testing of all 35 genotypes of forage sorghum was conducted using a randomized block design with three replications. Observations were recorded for days to 50% flowering, plant height (cm), leaf breadth (cm), leaf length (cm), number of leaves per plant, total soluble solids (%), leaf area (cm2), stem girth (mm), leaf stem ratio and green fodder yield per plant (g). Correlation coefficient studies indicated that green fodder yield per plant was found highly significant positive association with leaf breadth, stem girth, leaf area, leaf length, number of leaves per plant, plant height and leaf stem ratio at both genotypic and phenotypic level, indicated that selection of these attributes may be helpful to increase fodder yield in sorghum. The results of genotypic and phenotypic path analysis indicated that stem girth had a strong positive direct effect on green fodder yield per plant, followed by leaf breadth and number of leaves per plant at both genotypic and phenotypic levels. Improving these attributes can increase fodder yield. The character showing indirect effect like Leaf breadth, leaf length, leaf area, and leaf stem ratio via another component trait, indirect selection through such trait can lead to improvement in green fodder yield.

The role of protected areas and land tenure regimes on forest loss in Bolivia: Accounting for spatial spillovers

The conversion of tropical forests to croplands and grasslands is a major threat to global biodiversity, climate and local livelihoods and ecosystems. The enforcement of protected areas as well as the clarification and strengthening of collective and individual land property rights are key instruments to curb deforestation in the tropics. However, these instruments are territorial and can displace forest loss elsewhere. We investigate the effects of protected areas and various land tenure regimes on deforestation and possible spillover effects in Bolivia, a global tropical deforestation hotspot. We use a spatial Durbin model to assess and compare the direct and indirect effects of protected areas and different land tenure forms on forest loss in Bolivia from 2010 to 2017. We find that protected areas have a strong direct effect on reducing deforestation. Protected areas – which in Bolivia are all based on co-management schemes - also protect forests in adjacent areas, showing an indirect protective spillover effect. Indigenous lands however only have direct forest protection effects. Non-indigenous collective lands and small private lands, which are associated to Andean settlers, as well as non-titled lands, show a strong positive direct effect on deforestation. At the same time, there is some evidence that non-indigenous collective lands also encourage deforestation in adjacent areas, indicating the existence of spillovers. Interestingly, areas with high poverty rate tend to be less affected by deforestation whatever tenure form. Our study stresses the need to assess more systematically the direct and indirect effects of land tenure and of territorial governance instruments on land use changes.

Genetic Variability and Association Analysis in Chickpea (Cicer arietinum L.) for Seed Yield Characters

During Rabi, 2019-2020, the present trial was carried out at the field experimentation centre of the Genetics and Plant Breeding, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences, Allahabad to assess genetic variability, correlation and path analysis in twenty-six chickpea genotypes, including one check variety Uday for twelve quantitative traits. The analysis of variance revealed significant variations across genotypes for all of the features under investigation, demonstrating a high level of genetic variability in the experimental material. The genotypes C-224, C-201, ICC-16693, C-1028, C-129, C-213, C-130 and C-1025 have been identified as the top performing lines among the genotypes studied. PCV values were found to be higher than GCV for all of the traits investigated, indicating that environmental variables influence the characters. The fact that biological yield per plant has a high PCV and GCV implies that there is a lot of genetic variability in the material for these qualities. Plant height, days to 50% flowering, harvest index, biological yield per plant, hundred seed weight, seed yield per plant and number of pods per plant were all found to have high heritability. For the traits of biological yield per plant, seed index, harvest index, number of pods per plant, seed yield per plant and plant height, high heritability was observed along with high genetic advance as percent of mean, indicating that these characters were primarily governed by additive gene effects. As a result of the accumulation of more additive genes, direct selection of these features using a simple selection strategy would be efficient, leading to further development of chickpea genotypes. Number of seeds per plant, number of pods per plant, biological yield per plant, number of primary branches per plant, number of secondary branches per plant and plant height all had positive significant genotypic and phenotypic associations with grain yield per plant. At the phenotypic level, biological yield per plant and number of seeds per plant both had a strong positive direct effect on grain yield per plant and contributed the most to yield per plant.

English

Correlation Study with Path analysis was performed on 29 Lentil Genotypes to determine direct and indirect effect of some morphological as well as Biochemical parameters on Yield. Following traits were studied: Root Nodule number, Nodule weight, Primary Root Length, Secondary root numbers, Root Fresh and Dry weight, Plant Height, Pods per plant, Days to 50% Flowering, 100 seed weight, Leaf chlorophyll content, Seed Carbohydrate with Starch content, Seed Protein content and Yield. Considering both genetic Advance and GCV, it was observed that selection for the following characters viz. Plant Height, Pods per plant, Days to 50% flowering, 100 seed weight, Seed Protein content & Yield will be rewarding. Seed Yield per plant showed significantly Positive correlation with the following traits: 100 Seed weight, Pod number per plant, Plant height and seed starch. Negative association with yield was found for Days to 50% flowering. Path coefficient study revealed that there was a strong positive direct effect of 100 seed weight and Pod no. per plant along with Leaf Chlorophyll content on Yield. Hence, direct selection only for Pods number and 100 seed weight will be rewarding as these characters also gave higher heritability % along with high Genetic advance. Plant height gave strong negative direct effect on yield, but it gave a positive correlation due to high indirect effect in association with pod number. It may be due to short winter span of West Bengal which results into forced maturity of the crops. So short plants with higher pod numbers will be desirable for higher yield in short winter span condition.

Genotypic and Phenotypic Correlation and Path Coefficient for Quantitative Traits in Field Pea (<i>Pisum sativum</i> L.) Genotypes at Arsi Highland of Ethiopia

In Ethiopia, field pea (<i>Pisum sativum</i> L.) is the main source of protein for resource poor growers. The improvement of varieties for yield and disease resistance is one of the important activities to support farmers and improve the productivity of the crop. Consequently, this study was showed to evaluate the genotypic correlations, phenotypic correlations and path coefficient analysis between the field pea genotypes for yield and yield associated traits. Forty-nine field pea genotypes were evaluated in simple lattice design at two locations Bekoji and Asasa in 2018/2019 cropping time of year. Grain yield per plot had positive and highly significant genotypic association through plant height whereas highly significant phenotypic correlation observed between grain yield and plant height and biomass yield. At Bekoji genotypic path analysis, days to 50% flowering, plant height, grain filling period, thousand seed weight, harvest index and total biomass showed strong positive direct effect on grain yield per plot. At Asasa the path analysis for grain yield at genotypic level showed that harvest index, thousand seed weight, plant height, days to 50% flowering and days to 95% physiological maturity and total biomass yield exerted positive direct effect on grain yield per plot. Path coefficient analysis at genotypic levels of the combined data exhibited that days to 50% flowering and total biomass per plot had strong positive direct effect on grain yield per plot. The phenotypic path analysis of the combined data revealed total biomass yield, thousand seed weight, plant height and days to maturity has strong positive direct effect on grain yield per plot. The study showed the existence of reasonable genetic variability between the field pea genotypes that can be exploited in breeding programs.

Can internal marketing activities save small and medium industrial enterprises in a tough economy Back to the basics approach

Recently, and due to the economic pressure in Jordan, several small and medium enterprises have filed for bankruptcy, or downsized their business leading to the layout of hundreds of employees, which will deepen the economic problems in Jordan and increase the circle of effect. Small and medium enterprises can follow other courses of actions to address such issue. This paper aims to understand the possible impact of internal marketing practices and activities during economic problems on the employees' productivity in small and medium industrial enterprises. In order to achieve this aim, a descriptive analytical methodology was used, quantitative approach through survey strategy was applied and electronically administrated questionnaires were utilised to collect the primary data from a representative stratified random sample of 490 small and medium industrial enterprises out of 2,291 registered local small and medium industrial enterprises. 345 filtered and screened questionnaires were analysed using SPSS, the main results of simple and multiple regression analyses indicate that internal marketing mix has a strong positive direct effect on employees' productivity, where internal promotion has the most effect followed by workplace, internal product and internal price respectively. Discussion, conclusion, and recommendations are provided based on the results of the study.

Local and Landscape Compositions Influence Stingless Bee Communities and Pollination Networks in Tropical Mixed Fruit Orchards, Thailand

Stingless bees are vital pollinators for both wild and crop plants, yet their communities have been affected and altered by anthropogenic land-use change. Additionally, few studies have directly addressed the consequences of land-use change for meliponines, and knowledge on how their communities change across gradients in surrounding landscape cover remains scarce. Here, we examine both how local and landscape-level compositions as well as forest proximity affect both meliponine species richness and abundance together with pollination networks across 30 mixed fruit orchards in Southern Thailand. The results reveal that most landscape-level factors significantly influenced both stingless bee richness and abundance. Surrounding forest cover has a strong positive direct effect on both factors, while agricultural and urbanized cover generally reduced both bee abundance and diversity. In the local habitat, there is a significant interaction between orchard size and floral richness with stingless bee richness. We also found that pollinator specialization in pollination networks decreased when the distance to the forest patch increased. Both local and landscape factors thus influenced meliponine assemblages, particularly the forest patches surrounding an orchard, which potentially act as a key reservoir for stingless bees and other pollinator taxa. Preservation of forest patches can protect the permanent nesting and foraging habitat of various pollinator taxa, resulting in high visitation for crop and wild plants.

Direct and indirect effects of land-use intensity on plant communities across elevation in semi-natural grasslands.

Grassland biodiversity is vulnerable to land use change. How to best manage semi-natural grasslands for maintaining biodiversity is still unclear in many cases because land-use processes may depend on environmental conditions and the indirect effects of land-use on biodiversity mediated by altered abiotic and biotic factors are rarely considered. Here we evaluate the relative importance of the direct and indirect effects of grazing intensity on plant communities along an elevational gradient on a large topographic scale in the Eastern Carpathians in Ukraine. We sampled for two years 31 semi-natural grasslands exposed to cattle grazing. Within each grassland site we measured plant community properties such as the number of species, functional groups, and the proportion of species undesirable for grazing. In addition, we recorded cattle density (as a proxy for grazing intensity), soil properties (bare soil exposure, soil organic carbon, and soil pH) and densities of soil decomposers (earthworms and soil microorganisms). We used structural equation modelling to explore the direct and indirect effects of grazing intensity on plant communities along the elevation gradient. We found that cattle density decreased plant species and functional diversity but increased the proportion of undesirable species. Some of these effects were directly linked to grazing intensity (i.e., species richness), while others (i.e., functional diversity and proportion of undesirable species) were mediated via bare soil exposure. Although grazing intensity decreased with elevation, the effects of grazing on the plant community did not change along the elevation gradient. Generally, elevation had a strong positive direct effect on plant species richness as well as a negative indirect effect, mediated via altered soil acidity and decreased decomposer density. Our results indicate that plant diversity and composition are controlled by the complex interplay among grazing intensity and changing environmental conditions along an elevation gradient. Furthermore, we found lower soil pH, organic carbon and decomposer density with elevation, indicating that the effects of grazing on soil and related ecosystem functions and services in semi-natural grasslands may be more pronounced with elevation. This demonstrates that we need to account for environmental gradients when attempting to generalize effects of land-use intensity on biodiversity.

Association of traits in Ethiopian fenugreek (Trigonella foenum-graecum L.) genotypes regarding to seed yield by using phenotypic data

Shortage of information on association of traits is one of the problems in fenugreek productivity. Field experiment was implemented at Jamma district of South Wollo Administrative Zone of Amhara National Regional State, in 2018/19 main rainy season to examine the nature and extent of correlation, direct and indirect effects among yield and yield related traits. Sixty-two nationally collected fenugreek genotypes along with standard and local checks were evaluated in simple lattice design. Seed yield plot-1 was significantly and positively correlated to biomass yield-1 (r = 0.5) and harvest index (r = 0.6***) at genotypic level. Seed yield was also significantly and positively correlated with harvesting index (r = 0.6***) and weakly and negatively (r = -0.01) correlated to biomass yield at phenotypic level. Path coefficient analysis revealed that biomass (0.951), harvesting index (0.283) and pod length (-0.163) had contributed the maximum positive and negative direct effect on seed yield respectively, at phenotypic level. At genotypic level biomass yield ha-1 (0.816) and harvesting index (0.930) had contributed strong positive direct effect and plant height (-0.004) had revealed weak negative direct effect.

Floral preferences of hoverflies (Diptera: Syrphidae) in response to the abundance and species richness of flowering plants

For understanding the relationship between floral resources and the abundance of hoverflies, five meadows were selected at different elevations in a forested region. At each site the number of flowering herbaceous plants was assessed along a transect at 10-m intervals. To measure floral density, we counted the number of open flowers per species in each plot. Hoverflies visiting flowering plants were captured in each plot during 10 minutes. Path analysis showed that there was a negative correlation between plant species richness and syrphid abundance. Flower abundance had a strong positive direct effect on syrphid abundance but had indirect effects on the number of syrphid species. Only altitude had a strong positive direct effect on the number of syrphid species and this may be explained by the different climatic conditions. Some plant species attracted more syrphids than others. There were significantly fewer species of hoverfly per plot with increasing numbers of flowers. We interpret this to mean that plant species with a high density of flowers attracted more syrphids of the same species. Analysis of pollen grains extracted from two species of hoverflies showed that flower constancy occurred in three examined sites.

Linking hypothesized causal factors to aboveground biomass growth in forests of Alabama and the eastern United States

Aim of study: We analyzed the hypothesized causal effects of relative density, density, height, species richness, species diversity, temperature, precipitation, and slope on above ground biomass growth (AGBG).Area of study: Eastern region of the USA.Materials and methods: We used the USDA Forest Service’s Forest Inventory and Analysis (FIA) database. A total of 2554 plots from all stand ages, regardless of disturbance history, were selected from the state of Alabama and 967 plots of stand age under 30 years and no prior disturbance were selected from the eastern US. We analyzed the data using descriptive statistics and structural equation modeling.Main results: Relative stand density exhibited a strong positive direct effect on AGBG, especially in the young forests (path coefficient 0.79), but a weaker indirect effect through species richness/diversity. Tree height influenced positively AGBG directly and indirectly through relative density and species richness. The effect of temperature and slope was greater than the effect of species richness/diversity on AGBG in the young forests of the eastern US.Research highlights: For the forests of the eastern US, greater tree species diversity did not appear to result in neither greater nor lower productivity. The diversity-productivity relationship was negative in forests of Alabama, however, where prior management likely resulted in removal of select dominant trees from valuable species (i.e., high-grading).

The mediation roles of intraspecific and interspecific functional trait diversity for linking the response of aboveground biomass to species richness across forest strata in a subtropical forest

Intraspecific functional trait diversity (FTD) has improved our understandings about the key mechanisms of species coexistence in plant communities. Yet, little is known about whether and how intraspecific and interspecific FTD mediate the response of aboveground biomass to species richness across forest strata (i.e. overstorey and understorey) and at whole-community in forests. To address this question, we tested the direct and indirect responses of aboveground biomass to species richness via intraspecific and interspecific FTD based on specific leaf area (FTDSLA) and leaf dry matter content (FTDLDMC) using structural equation modeling, in addition to the effects of soil nutrients, across 125 plots in a 5-ha subtropical forest in Eastern China. Results showed that intraspecific FTD mediates the response of aboveground biomass to species richness at overstorey and understorey strata, and whole-community level, while interspecific FTD did so at understorey strata only. At overstorey strata, 14% of the variation in aboveground biomass was accounted by the strong direct positive effect of species richness only. At understorey strata, soil nutrients had a strong negative direct effect followed by positive effects of species richness and FTDLDMC on aboveground biomass with 44–45% of the variation in both intraspecific and interspecific FTD models. At whole community level, 14% of the variation in aboveground biomass was explained by the strong positive direct effect of species richness followed by negative direct effect of intraspecific FTDSLA. Intraspecific and interspecific FTDLDMC had positively mediated the response of aboveground biomass to species richness at understorey strata through niche differentiation. Intraspecific FTD had negligible mediation role, whereas interspecific FTD had no role, for linking the response of aboveground biomass to species richness at overstorey strata, indicating that only dominant species with a specific functional strategy may largely determine community trait space. Intraspecific FTDSLA had negative relationship with aboveground biomass at the whole-community, probably due to the presence of a few large trees occupying larger niche space in a community. We conclude that intraspecific versus interspecific FTD plays a central role for linking the direct and indirect responses of aboveground biomass to species richness, but these relationships depend on the forest strata of a community.

The positive relationships between plant coverage, species richness, and aboveground biomass are ubiquitous across plant growth forms in semi-steppe rangelands

The positive relationships between biodiversity and aboveground biomass are important for biodiversity conservation and greater ecosystem functioning and services that humans depend on. However, the interaction effects of plant coverage and biodiversity on aboveground biomass across plant growth forms (shrubs, forbs and grasses) in natural rangelands are poorly studied. Here, we hypothesized that, while accounting for environmental factors and disturbance intensities, the positive relationships between plant coverage, biodiversity, and aboveground biomass are ubiquitous across plant growth forms in natural rangelands. We applied structural equation models (SEMs) using data from 735 quadrats across 35 study sites in semi-steppe rangelands in Iran. The combination of plant coverage and species richness rather than Shannon's diversity or species diversity (a latent variable of species richness and evenness) substantially enhance aboveground biomass across plant growth forms. In all selected SEMs, plant coverage had a strong positive direct effect on aboveground biomass (β = 0.72 for shrubs, 0.84 for forbs and 0.80 for grasses), followed by a positive effect of species richness (β = 0.26 for shrubs, 0.05 for forbs and 0.09 for grasses), and topographic factors. Disturbance intensity had a negative effect on plant coverage, whereas it had a variable effect on species richness across plant growth forms. Plant coverage had a strong positive total effect on aboveground biomass (β = 0.84 for shrubs, 0.88 for forbs, and 0.85 for grasses), followed by a positive effect of species richness, and a negative effect of disturbance intensity across plant growth forms. Our results shed light on the management of rangelands that is high plant coverage can significantly improve species richness and aboveground biomass across plant growth forms. We also found that high disturbance intensity due to heavy grazing has a strong negative effect on plant coverage rather than species richness in semi-steppe rangelands. This study suggests that proper grazing systems (e.g. rotational system) based on carrying capacity and stocking rate of a rangeland may be helpful for biodiversity conservation, better grazing of livestock, improvement of plant coverage and enhancement of aboveground biomass.

Disentangling the effects of species diversity, and intraspecific and interspecific tree size variation on aboveground biomass in dry zone homegarden agroforestry systems

The biodiversity – aboveground biomass relationship has been intensively studied in recent decades. However, no consensus has been arrived to consider the interplay of species diversity, and intraspecific and interspecific tree size variation in driving aboveground biomass, after accounting for the effects of plot size heterogeneity, soil fertility and stand quality in natural forest including agroforests. We tested the full, partial and no mediations effects of species diversity, and intraspecific and interspecific tree size variation on aboveground biomass by employing structural equation models (SEMs) using data from 45 homegarden agroforestry systems in Sri Lanka. The full mediation effect of either species diversity or intraspecific and interspecific tree size variation was rejected, while the partial and no mediation effects were accepted. In the no mediation SEM, homegarden size had the strongest negative direct effect (β=−0.49) on aboveground biomass (R2=0.65), followed by strong positive direct effect of intraspecific tree size variation (β=0.32), species diversity (β=0.29) and interspecific tree size variation (β=0.28). Soil fertility had a negative direct effect on interspecific tree size variation (β=−0.31). Stand quality had a significant positive total effect on aboveground biomass (β=0.28), but homegarden size had a significant negative total effect (β=−0.62), while soil fertility had a non-significant total effect on aboveground biomass. Similar to the no mediation SEM, the partial mediation SEMs had explained almost similar variation in aboveground biomass because species diversity, and intraspecific and interspecific tree size variation had non-significant indirect effects on aboveground biomass via each other. Our results strongly suggest that a multilayered tree canopy structure, due to high intraspecific and interspecific tree size variation, increases light capture and efficient utilization of resources among component species, and hence, support the niche complementarity mechanism via plant-plant interactions.

Direct and indirect effect of the oat (Avena sativa L.) component characters on the dry forage production

Oat ( Avena sativa L.), one of the important dual purpose crops of the world is grown for food and forage purpose. In India it is exclusively grown as fodder. Sixteen genotypes of oat were grown at the Central Research Farm of Bidhan Chandra Krishi Viswavidyalaya, Gayeshpur, Nadia, W. Bengal in the Rabi season of 2010-11 to estimate the direct and indirect effect of the component characters on the dry matter production. Path analysis carried out considering total dry weight per tiller at 50 per cent flowering as the dependent variable revealed in some characters like plant height at 20 days, fresh weight of per tiller at 40 days, dry weight of leaves per tiller at 40 days, total dry weight per tiller at 40 days and total chlorophyll content in spite of negative direct effect, the correlation value was positive. Again in some characters in spite of significantly positive direct effect, the correlation value was negative e.g. fresh weight of leaves per tiller at 50 per cent flowering. But characters like plant height at 40 days, plant height at 50 per cent flowering, fresh weight per tiller at 50 per cent flowering, dry weight of leaves per tiller at 50 per cent flowering, fresh weight of stem per tiller at 50 per cent flowering, dry weight of stem per tiller at 50 per cent flowering and chlorophyll 'a' both direct effect and correlation were positive. In case of dry weight per plant at 20 days, fresh weight of stem per tiller at 40 day, dry weight of stem per tiller at 40 days, dry weight of flag leaf and chlorophyll 'b' there was strong positive direct effect but no correlation could be established with dry weight of stem per tiller at 50 per cent flowering.

Direct and indirect effects of morphophysiological traits on kernel protein content of confectionary sunflower

The most important criterion for introducing new confectionary sunflower hybrids into production is high protein yield. In the breeding process it is important to identify traits which could be used as selection criteria for increased kernel protein content. Increase of kernel protein content results in increased protein yield. This research was conducted during three vegetation seasons on 22 NS high-protein two-line confectionary sunflower hybrids produced within the breeding program at IFVCNS, Novi Sad, Serbia. Strong and very strong correlations were found among the largest number of examined traits. Based on the analysis of simple correlation coefficients, strong negative correlation was determined between kernel protein content and kernel ratio (-0.516*). A weak negative interdependence was determined between head diameter, seed protein content, and kernel protein content. Positive but weak correlation was determined between kernel protein content and thickness of seed, length of seed, width of seed, and 1000 seed weight. Path coefficient analysis for kernel protein content at phenotypic level showed that the thickness of seed had a strong positive direct effect on kernel protein content (DE=382*). Kernel ratio and width of seed had a very strong direct negative effect on kernel protein content (DE=-0.990**; DE=0.600**). A weak direct positive effect of head diameter, seed protein content and length of seed was established, whereas 1000 seed weight had a weak direct negative effect on kernel protein content. Path coefficient analysis indicates showed that the thickness of seed has high great influence on kernel protein content, and an important selection criterion for breeding for high protein yield.

Community-weighted mean of leaf traits and divergence of wood traits predict aboveground biomass in secondary subtropical forests

Subtropical forests are globally important in providing ecological goods and services, but it is not clear whether functional diversity and composition can predict aboveground biomass in such forests. We hypothesized that high aboveground biomass is associated with high functional divergence (FDvar, i.e., niche complementarity) and community-weighted mean (CWM, i.e., mass ratio; communities dominated by a single plant strategy) of trait values. Structural equation modeling was employed to determine the direct and indirect effects of stand age and the residual effects of CWM and FDvar on aboveground biomass across 31 plots in secondary forests in subtropical China. The CWM model accounted for 78, 20, 6 and 2% of the variation in aboveground biomass, nitrogen concentration in young leaf, plant height and specific leaf area of young leaf, respectively. The FDvar model explained 74, 13, 7 and 0% of the variation in aboveground biomass, plant height, twig wood density and nitrogen concentration in young leaf, respectively. The variation in aboveground biomass, CWM of leaf nitrogen concentration and specific leaf area, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf explained by the joint model was 86, 20, 13, 7, 2 and 0%, respectively. Stand age had a strong positive direct effect but low indirect positive effects on aboveground biomass. Aboveground biomass was negatively related to CWM of nitrogen concentration in young leaf, but positively related to CWM of specific leaf area of young leaf and plant height, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf. Leaf and wood economics spectra are decoupled in regulating the functionality of forests, communities with diverse species but high nitrogen conservative and light acquisitive strategies result in high aboveground biomass, and hence, supporting both the mass ratio and niche complementarity hypotheses in secondary subtropical forests.

Digital Fit as a Leg-Up for Nongovernmental Organizations’ Media and Political Success

Two important and understudied dimensions of the interaction between politics and the digital revolution are the impact of digital technology on the ability of nongovernmental organizations (NGOs) to win more media coverage and to successfully influence the political processes. This original quantitative comparison of 50 Israeli NGOs examined two main issues: the impact of technology on the ability of organizations to achieve mass media and political success and whether some groups are better positioned than others to exploit technology to their advantage. A theoretical concept labeled digital fit was introduced and put to a statistical test using data from a survey of 50 NGO leaders and a survey of 15 key politicians who were asked to rank the political impact of organizations they are familiar with from relevant parliamentary committees they are members of. Digital fit is defined as a cluster of digitally related variables that puts political actors in a better position to harness digital technology to self-produce and self-distribute multimedia messages for the purpose of advocating their cause to mass media outlets and politicians. A prospective dimension of digital fit is its potential to stimulate power shifts between the old guard of successful political-communication actors and a new breed of successful challengers. Results showed that digital fit had a strong positive direct effect on mass media success and a mediated influence on political success. There are positive signs that conventional models are shifting in a way that empowers new political actors.

The path coefficient analysis of yield components for leaf nutrient concentrations in Mango (Mangifera indica L.) under rainfed agroclimatic conditions of north-west Himalaya

This study aimed to understand the relationship for productivity related traits using correlations and path coefficient analysis of ‘Dashehari’ mango under rainfed agro-climatic zone conditions of north-west Himalayas of India. The study also identifies the relationship among agronomic and yield-related characteristics to know the direct and indirect effect of independent variables on managerial ability of the crop. Correlation and path coefficient analyses were carried out over two consecutive years (2004, 2005) seasons for plant growth (tree trunk), leaf nutrient concentration, and fruit yield across four districts of Himachal Pradesh. Based on yield performance, an optimum sample size of 20 trees from each orchard comprised of 10 trees each of two categories: high productive (>90kgtree−1) and low productive (<90kgtree−1) were selected using the probability proportional to size multistage sampling scheme. Both high as well as low productive orchards were analyzed for soil and leaf chemical properties. Simple linear correlation and path coefficient analyses were worked out between all possible combinations. The contribution of leaf nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe) on growth and fruit yield was studied. In high productive trees, path model showed that leaf N, Mg, Fe, Cu and Mn concentrations recorded the high magnitude of direct effect on fruit yield. However, leaf N concentration had a strong positive indirect effect through leaf Zn. Leaf Cu and Zn concentrations had a positive indirect effect through leaf Mg and leaf Zn on fruit yield. In low productive trees, leaf N concentration had a strong positive direct effect and a strong positive indirect effect via leaf Zn on fruit yield. Similarly, the direct effect of tree volume on fruit yield was positive, while, the maximum positive indirect effect was through leaf K. A residual value of 0.7308 and 0.7292 indicates the collective influence of the variables was to the magnitude of 0.2692 and 0.2708 to the extent of 26.9 and 27.1% toward fruit yield, and contributed 40.7 and 14.7% toward tree volume in high and low productive mango trees, respectively. The collective influence of the variables included on tree volume to the magnitude of 0.8521 and concluded that leaf nutrient content has been contributed to the extent of 14.7% toward tree volume.