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

Abstract 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.

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Diversity Influences Tree Aboveground Carbon Stocks Through Functional Diversity and Functional Dominance in the Dry Evergreen Afromontane Forest of Hararghe Highland, Southeast Ethiopia

10.21203/rs.3.rs-53977/v1 ◽

2020 ◽

Author(s):

Mengistu Teshome ◽

Zebene Asfaw ◽

Muktar Mohammed

Keyword(s):

Species Diversity ◽

Plant Height ◽

Functional Diversity ◽

Ecosystem Function ◽

Carbon Stock ◽

Equation Modeling ◽

Selection Effects ◽

Niche Complementarity ◽

Aboveground Carbon ◽

Biodiversity And Ecosystem Function

Abstract Background: The relationship between biodiversity and ecosystem function has increasingly been debated as the key ecological issues behind ecosystem service provision. Still, many experimental and theoritical based studies have reported inconsistent patterns of biodiversity and ecosystem function relationships, supporting either niche complementarity or selection effect hypothesis. In this study, aboveground carbon (AGC) stock used as a proxy for ecosystem function and examined its relationship with species diversity, through functional diversity and functional dominance. It is hypothesized that (i) diversity influences AGC through functional diversity and functional dominance effects; and (ii) effects of diversity on AGC would be parted for both functional dominance and functional diversity. Community weight mean (CWM) of functional traits (wood density, specific leaf area, and maximum plant height) was calculated to assess functional dominance (selection effects). As for functional diversity (complementarity effects), multi-trait functional diversity (selection effects) indices were computed. The first hypothesis was tested 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 both.Results: Results revealed that tree aboveground carbon varied significantly along the slope gradient. Species diversity (richness) had a positive relationship with aboveground carbon, even when elevation effects were considered. As predicted, diversity effects on aboveground carbon were mediated through functional diversity and functional dominance, suggesting that both the niche complementarity and the selection effects are not exclusively affecting carbon stock. However, the effects were greater for functional diversity than for functional dominance. Furthermore, functional dominance effects were strongly transmitted by CWM of maximum plant height, reflecting the importance of forest vertical stratification of diversity and carbon relationship. We therefore argue for stronger complementary effects that would be induced also by complementary light use efficiency of tree and species growing in the understory layer.Conclusions: Species diversity (richness) influences carbon stock through functional diversity and functional dominance. Both the niche complementarity and selection hypotheses are important predictors of carbon stock in the study forest.

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Tree species diversity promotes aboveground carbon storage through functional diversity and functional dominance

Ecology and Evolution ◽

10.1002/ece3.2525 ◽

2016 ◽

Vol 6 (20) ◽

pp. 7546-7557 ◽

Cited By ~ 36

Author(s):

Sylvanus Mensah ◽

Ruan Veldtman ◽

Achille E. Assogbadjo ◽

Romain Glèlè Kakaï ◽

Thomas Seifert

Keyword(s):

Species Diversity ◽

Carbon Storage ◽

Functional Diversity ◽

Tree Species ◽

Tree Species Diversity ◽

Aboveground Carbon ◽

Aboveground Carbon Storage

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Stand structural diversity and species with leaf nitrogen conservative strategy drive aboveground carbon storage in tropical old-growth forests

10.21203/rs.3.rs-27540/v1 ◽

2020 ◽

Author(s):

Genzhu Wang ◽

Yuguo Liu ◽

Xiuqin Wu ◽

Danbo Pang ◽

Xiao Yang ◽

...

Keyword(s):

Carbon Storage ◽

Structural Equation ◽

Structural Diversity ◽

Old Growth ◽

Elevation Gradients ◽

Niche Complementarity ◽

Aboveground Carbon ◽

Old Growth Forest ◽

Stand Structural Diversity ◽

Aboveground Carbon Storage

Abstract Background: Tropical old-growth forest ecosystems are essential for global carbon regulation. Even there are mounting evidences for the significance of species and functional composition, stand structure and elevation gradients on aboveground carbon storage, the relative strengths of these drivers and whether elevation effects via biotic factors are not clear. Furthermore, the mechanisms (the mass-ratio hypothesis or niche complementarity hypothesis) are still poorly understood. Methods: We analyzed aboveground carbon storage, species diversity, stand structural diversity, community-weighted mean (CWM) of functional traits and functional diversity (FDvar) using date from 56 old-growth forest communities with different elevation gradients in Dawei mountain of southwestern China. Multiple regression models were used to test the relative importance of the predictor variables and structural equation model was used to explore the direct and indirect influences on the aboveground carbon storage. Results: Our optimal multiple regression model show aboveground carbon storage is mostly affected by diameter at breast height (DBH) diversity, followed by FDvar of dry matter concentration in mature leaves and CWM nitrogen concentration in young leaves. The final structural equation model indicates elevation indirectly affected aboveground carbon storage via DBH diversity. The stand structural diversity, but not species diversity or functional diversity, enhanced aboveground carbon storage. Conclusions: Our results indicate mass-ratio and niche complementarity effect promote aboveground carbon storage simultaneously. The complex stand structure and species with leaf nitrogen conservative strategy were the crucial drivers of aboveground carbon storage in tropical old-growth forests.

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Stand Structural Diversity and Species with Leaf Nitrogen Conservation Drive Aboveground Carbon Storage in Tropical Old-Growth Forests

Forests ◽

10.3390/f11090994 ◽

2020 ◽

Vol 11 (9) ◽

pp. 994

Author(s):

Genzhu Wang ◽

Yuguo Liu ◽

Xiuqin Wu ◽

Danbo Pang ◽

Xiao Yang ◽

...

Keyword(s):

Carbon Storage ◽

Structural Equation ◽

Nitrogen Concentration ◽

Structural Diversity ◽

Old Growth ◽

Niche Complementarity ◽

Aboveground Carbon ◽

Old Growth Forests ◽

Stand Structural Diversity ◽

Aboveground Carbon Storage

Tropical old-growth forests are essential for global carbon regulation. Although there is increasing evidence that species and functional diversity, stand structural diversity, functional compositions, and elevation play roles in ecosystem functioning, the relative strengths of these drivers and the underlying mechanisms (mass-ratio hypothesis or niche complementarity hypothesis) are not clear. Aboveground carbon storage, species diversity, stand structural diversity, community-weighted mean (CWM), and functional diversity (FDvar) of 12 leaf traits were analyzed using data from 56 old-growth forest communities in the Dawei Mountain area of Southwest China. Multiple regression models were used to test the relative importance of the predictor variables and the structural equation model was used to explore the direct and indirect influences on aboveground carbon storage. High structural diversity moderately enhanced aboveground carbon storage. CWM leaf nitrogen concentration in young leaves weakly affected aboveground carbon storage. Our final multiple regression model showed that aboveground carbon storage is mostly affected by diameter at breast height (DBH) diversity, followed by FDvar of dry matter concentration in mature leaves and CWM nitrogen concentration in young leaves. The structural equation model indicated that elevation negatively affects aboveground carbon storage via diameter at breast height (DBH) diversity. Our results suggest that niche complementarity effects moderately drive aboveground carbon storage in tropical old-growth forests, but do not fully support the importance of the mass-ratio hypothesis.

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Tree aboveground carbon storage correlates with environmental gradients and functional diversity in a tropical forest

Scientific Reports ◽

10.1038/srep25304 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 7

Author(s):

Yong Shen ◽

Shixiao Yu ◽

Juyu Lian ◽

Hao Shen ◽

Honglin Cao ◽

...

Keyword(s):

Tropical Forest ◽

Carbon Storage ◽

Functional Diversity ◽

Environmental Gradients ◽

Aboveground Carbon ◽

Aboveground Carbon Storage

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Stand structural diversity and species with leaf nitrogen conservative strategy drive aboveground carbon storage in tropical old-growth forests

10.21203/rs.3.rs-27540/v2 ◽

2020 ◽

Author(s):

Genzhu Wang ◽

Yuguo Liu ◽

Xiuqin Wu ◽

Danbo Pang ◽

Xiao Yang ◽

...

Keyword(s):

Carbon Storage ◽

Structural Equation ◽

Structural Diversity ◽

Old Growth ◽

Elevation Gradients ◽

Niche Complementarity ◽

Aboveground Carbon ◽

Old Growth Forest ◽

Stand Structural Diversity ◽

Aboveground Carbon Storage

Abstract Background: Tropical old-growth forest ecosystems are essential for global carbon regulation. Even there are mounting evidences for the significance of species and functional composition, stand structure and elevation gradients on aboveground carbon storage, the relative strengths of these drivers and whether elevation effects via biotic factors are not clear. Furthermore, the mechanisms (the mass-ratio hypothesis or niche complementarity hypothesis) are still poorly understood.Methods: We analyzed aboveground carbon storage, species diversity, stand structural diversity, community-weighted mean (CWM) of functional traits and functional diversity (FDvar) using date from 56 old-growth forest communities with different elevation gradients in Dawei mountain of southwestern China. Multiple regression models were used to test the relative importance of the predictor variables and structural equation model was used to explore the direct and indirect influences on the aboveground carbon storage.Results: Our optimal multiple regression model show aboveground carbon storage is mostly affected by diameter at breast height (DBH) diversity, followed by FDvar of dry matter concentration in mature leaves and CWM nitrogen concentration in young leaves. The final structural equation model indicates elevation indirectly affected aboveground carbon storage via DBH diversity. The stand structural diversity, but not species diversity or functional diversity, enhanced aboveground carbon storage.Conclusions: Our results indicate mass-ratio and niche complementarity effect promote aboveground carbon storage simultaneously. The complex stand structure and species with leaf nitrogen conservative strategy were the crucial drivers of aboveground carbon storage in tropical old-growth forests.

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