Selection Effects of Soil Fertility on the Progenies of Soybean Crosses

The F2, F3, families and F4 lines of six soybean crosses, were selected successively under high-and low - fertility sites with the relection objective of high yield and the method of pedigree was used. Two best F4 - derived lines were chosen from each of the six crosses under both high-and low-fertility for use in this study. In 1995, the total 24 lines were tested in high, medium and low fertility sites with the same experimental design (CRB) to study the selcctoin effects of high and low - fertility. The results suggested that high- and low-fertility had different selection effects. High fertility was more effective for selecting lines, which had higher yield under high-fertility and lower yield under low-fertility; low-fertility was better for selecting lines, which had higher yield under low-fertility and lower yield under low-fertility, and high fertility was somewhat better than low fertility for selecting lines, which had higher yield under both high and low-fertility. It revealed that the lines selected from high-fertility had superior yield potential. The lines selected from high-fertility had shorter plant height, more nodes on main stem, fewer branches, higher seed-stem ratio. The reverse was true for the lines selected from low-fertility . The lodging-resistance of the lines selected from highfertility was greater than that of the lines from low-fertility. The soil fertility level of breeding nursery should be chosen according to the breeding objective.

Tree diversity effects on forest productivity increase through time because of spatial partitioning

Background: Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment(as of2018) in Japan.Results: I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages(≤ 3 years), the positive complementarity effect was explained by enhanced growths of early-and mid-successional species in the mixture. Later on(≥ 15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e. alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer.Conclusions: The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies.

EFFECT OF ELECTRON DONORS ON THE SELECTIVE HYDROGENATION OF DIENE TO MONOENE OVER HETEROGENIZED Pd CATALYST

In the selective hydrogenation of diene (or alkyne) using heterogenized homogeneous catalyst, the high selectivity of monoene formation only appears in a very short time interval. The addition of suitable electron donors can decrease or even cease the monoene hydrogenation and thereby keep the high monoene selectivity after reaching its maximum.

Selection of Fixed Effects in High-dimensional Generalized Linear Mixed Models

The selection of fixed effects is studied in high-dimensional generalized linear mixed models(HDGLMMs)without parametric distributional assumptions except for some moment conditions.The iterative-proxy-based penalized quasi-likelihood method(IPPQL)is proposed to select the important fixed effects where an iterative proxy matrix of the covariance matrix of the random effects is constructed and the penalized quasi-likelihood is adapted.We establish the model selection consistency with oracle properties even for dimensionality of non-polynomial(NP)order of sample size.Simulation studies show that the proposed procedure works well.Besides,a real data is also analyzed.

Incorporating metal nanoparticles in porous materials via selective heating effect using microwave

Metal nanoparticle@porous material composites have attracted increasing attention due to their excellent synergistic catalytic performance.However,it is a challenge to introduce metal nanoparticles into cavities of porous materials without agglomeration on the exterior.Despite the progress achieved,a universal approach that can integrate different kinds of metal nanoparticles and porous materials is still highly desirable.Here we report a facile and general approach to fabricating metal nanoparticle@porous materials by microwave-triggered selective heating.The microwave can pass through the non-polar solvent and act on the polar solvent in the porous materials,causing the polar solvent to be heated,vaporized,and away from the pores of porous materials.The local void produced by the escape of polar solvent facilitates non-polar solvent containing metallic precursor to be dragged into the narrow pores,followed by further reduction,resulting in the complete encapsulation of nanoparticles.A series of metal nanoparticles@porous materials,ranging from metal-organic frameworks(MOFs)to zeolites,are successfully prepared by this method and show excellent size selectivity in catalytic reactions.

Dieback intensity but not functional and taxonomic diversity indices predict forest productivity in different management conditions: Evidence from a semi-arid oak forest ecosystem

The relationships between different aspects of diversity(taxonomic,structural and functional)and the aboveground biomass(AGB)as a major component of global carbon balance have been studied extensively but rarely under the simultaneous influence of forest dieback and management.In this study,we investigate the relationships between taxonomic,functional and structural diversity of woody species(trees and shrubs)and AGB along a gradient of dieback intensity(low,moderate,high and no dieback as control)under two contrasted management conditions(protection by central government vs.traditional management by natives)in a semi-arid oak(Quereus brantii Lindl.)forest ecosystem.AGB was estimated and taxonomic diversity,community weighted average(CWM)and functional divergence indices were produced.We found that the aerial biomass was significantly higher in the intensively used area(14.57(±1.60)t/hm^(2))than in the protected area(8.70(±1.05)t/hm^(2))due to persistence of some large trees but with decreasing values along the dieback intensity gradient in both areas.CWM of height(H),leaf nitrogen content(LNC)and leaf dry matter content(LDMC)were also higher in the traditional managed area than in the protected area.In contrast,in the protected area,the woody species diversity was higher and the inter-specific competition was more intense,explaining a reduced H,biomass and LDMC.Contrary to the results of CWM,none of the functional diversity traits(FDvar)was affected by dieback intensity and only FDvar values of LNC,leaf phosphorus content(LPC)and LDMC were influenced by management.We also found significantly positive linear relationships of AGB with CWM and FDvar indices in the protected area,and with taxonomic and structural diversity indices in the traditional managed area.These results emphasize that along a dieback intensity gradient,the leaf functional traits are efficient predictors in estimating the AGB in protected forests,while taxonomic and structural indices provide better results in forests under a high human pressure.Finally,species identity of the dominant species(i.e.,Brant’s oak)proves to be the main driver of AGB,supporting the selection effect hypothesis.

Positive diversity effects on productivity in mixtures of arable weed species as related to density-size relationships

Aims Diversity-productivity relationships among herbaceous species have mostly been studied in grasslands,while less is known about diversity effects among weedy species with a short life cycle.Methods We studied diversity-productivity relationships,shoot density,size and allometry in experimental communities of different species richness(one,three,six,and nine species),functional group number(one to three functional groups:grasses,small herbs and tall herbs)and functional group evenness(even and uneven number of species per functional group)based on a pool of nine arable weed species with a short life cycle in a 2-year experiment.Important Findings Higher species richness increased above-and belowground biomass production in both years of the experiment.Additive partitioning showed that positive selection effects increased with increasing species richness and functional group number,while positive complementarity effects were greater when tall herbs were present.Relative yield totals were larger than 1 across all species richness levels but did not increase with species richness,which is consistent with constant positive complementarity effects.Community biomass production and diversity effects increased in the second year of the experiment,when communities achieved greater shoot densities and average shoot sizes.At the community level,varying productivity was mainly attributable to variation in mean shoot sizes.Tall herbs reached greater observed/expected relative yields(=overyielding)due to increased shoot sizes,underyielding of small herbs was mainly attributable to decreased shoot sizes,while grasses partly compensated for reduced shoot sizes by increasing densities.Shifts in community-level density-size relationships and changes in shoot allometry in favour of greater height growth indicated that a greater biomass at a given density was due to increased dimensions of occupied canopy space.We conclude that diversity effects are also possible among short-lived arable weed species,but selection effects through sizes differences among species are key for positive species richness-productivity relationships.

Aboveground carbon stock is related to land cover and woody species diversity in tropical ecosystems of Eastern Ethiopia

Background:Current theories on biodiversity-carbon sequestration relationship describe biodiversity as an important factor influencing carbon storage,either through complementarity effect or by mass ratio effect.So far,the expected form of biodiversity-carbon relationships in tropical ecosystems has not been known with certainty.Therefore,we explored the relationship between aboveground carbon stock and different biodiversity measurement indices(i.e.,species richness,species diversity,species evenness,and functional diversity)in different land cover types of Eastern Ethiopia.A total of 48 plots were established using stratified random sampling.Vegetation parameters such as diameter at breast height,diameter at stump height,tree height,and species type were recorded.Results:We found that the average aboveground carbon stock of the study area is 147.6±17.2 t ha^(−1)(mean,SE)across land cover types.Species richness,Shannon index,and functional diversity together explained 73.5%,61.4%,58.9%,and 52.0%of the variation in aboveground carbon storage in woodland,riparian forest,bushland,and farmland,respectively.Functional diversity was a significant predictor explaining the total aboveground carbon stocks(26.7%)across the land cover types.The effects of biodiversity on aboveground carbon storage were mediated by functional diversity and presence and dominance of species.This shows that both the selection effects and the niche complementarity are important for carbon storage.However,the impact of functional diversity effects(niche complementarity)was higher than that of functional dominance effects(selection effects).Conclusions:Implementation of protected area-based ecosystem conservation practices in the country seems feasible to mitigate climate change and Reducing Emissions from Deforestation and Forest Degradation(REDD+)programme should emphasize on biodiversity conservation.

Tree species diversity predicts aboveground carbon storage through functional diversity and functional dominance in the dry evergreen Afromontane forest of Hararghe highland, Southeast Ethiopia

Background:Regarding the most important ecological challenges,scientists are increasingly debating the relationship between biodiversity and ecosystem function.Despite this,several experimental and theoretical researches have shown inconsistencies in biodiversity and ecosystem function relationships,supporting either the niche complementarity or selection effect hypothesis.The relationship between species diversity,functional diversity,and aboveground biomass carbon was investigated in this study employing standing aboveground carbon(AGC)stock as a proxy measure for ecosystem function.We hypothesized that(i)effects of diversity on AGC can be transmitted through functional diversity and functional dominance;(ii)effects of diversity on AGC would be greater for functional dominance than functional diversity;and(iii)effects of functional diversity and functional dominance on carbon stock varied with metrics and functional traits.Community-weighted means(CWM)of functional traits(wood density,specific leaf area,and maximum plant height)were calculated to assess functional dominance(selection effects).As for functional diversity(complementarity effects),multi-trait functional diversity(selection effects)indices were computed.We tested the first hypothesis using structural equation modeling.For the second hypothesis,the effects of environmental variables such as slope,aspect,and elevation were tested first,and separate linear mixed-effects models were fitted afterward for functional diversity,functional dominance,and the two together.Results:Results revealed that slope had a significant effect on aboveground carbon storage.Functional diversity and functional dominance were significant predictors of the aboveground carbon storage(22.4%)in the dry evergreen Afromontane forest.The effects of species richness on aboveground carbon storage were mediated by functional diversity and functional dominance of species.This shows that both the selection effects and the niche complementarity are important for aboveground carbon storage prediction.However,the functional diversity effects(niche complementarity)were greater than functional dominance effects(selection effects).Conclusions:Linking diversity and biodiversity components to aboveground carbon provides better insights into the mechanisms that explain variation in aboveground carbon storage in natural forests,which may help improve the prediction of ecosystem functions.