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The influences of canopy species and topographic variables on understory species diversity and composition in coniferous forests.

Huo H, Feng Q, Su YH - ScientificWorldJournal (2014)

Bottom Line: Many heliophilous species were significantly associated with juniper forest, while only one species was indicative of spruce forest.Using constrained ordination and the variation partitioning model, we quantitatively assessed the relative effects of two sets of explanatory variables on understory species composition.The results showed that topographic variables had higher explanatory power than did site conditions for understory plant distributions.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Ecohydrology of Inland River Basin, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China ; University of Chinese Academy of Sciences, Beijing 100049, China.

ABSTRACT
Understanding the factors that influence the distribution of understory vegetation is important for biological conservation and forest management. We compared understory species composition by multi-response permutation procedure and indicator species analysis between plots dominated by Qinghai spruce (Picea crassifolia Kom.) and Qilian juniper (Sabina przewalskii Kom.) in coniferous forests of the Qilian Mountains, northwestern China. Understory species composition differed markedly between the forest types. Many heliophilous species were significantly associated with juniper forest, while only one species was indicative of spruce forest. Using constrained ordination and the variation partitioning model, we quantitatively assessed the relative effects of two sets of explanatory variables on understory species composition. The results showed that topographic variables had higher explanatory power than did site conditions for understory plant distributions. However, a large amount of the variation in understory species composition remained unexplained. Forward selection revealed that understory species distributions were primarily affected by elevation and aspect. Juniper forest had higher species richness and α-diversity and lower β-diversity in the herb layer of the understory plant community than spruce forest, suggesting that the former may be more important in maintaining understory biodiversity and community stability in alpine coniferous forest ecosystems.

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The CCA ordination of 27 plots and environmental variables. Arrows indicate the environmental variables (Ele, elevation; Asp, aspect; Slo, slope; Pos, slope position; BA, basal area; Cov, canopy cover; Den, tree density). Plots dominated by P. crassifolia and S. przewalskii are represented by circles (n = 16) and squares (n = 11), respectively.
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fig1: The CCA ordination of 27 plots and environmental variables. Arrows indicate the environmental variables (Ele, elevation; Asp, aspect; Slo, slope; Pos, slope position; BA, basal area; Cov, canopy cover; Den, tree density). Plots dominated by P. crassifolia and S. przewalskii are represented by circles (n = 16) and squares (n = 11), respectively.

Mentions: In the CCA ordination, a Monte Carlo permutation test indicated that the eigenvalues for the first axis and those for all canonical axes were significant (P < 0.01), revealing that understory species composition was related to the measured variables (Figure 1). The first four axes explained 35.9% of the cumulative variance in species data and 83.3% of the variance in the relationship between understory species composition and environmental variables. CCA results showed that the first axis was significantly associated with elevation (r = −0.775), aspect (r = −0.474), slope (r = −0.464), canopy cover (r = 0.574), basal area (r = 0.467), and tree density (r = 0.607). The second axis was closely correlated with aspect (r = 0.611), slope position (r = 0.378), and SOIL (r = −0.588) (Figure 1; Table 3). Forward selection in the CCA ordination showed that understory species composition was primarily affected by elevation and aspect (P < 0.05; Table 4).


The influences of canopy species and topographic variables on understory species diversity and composition in coniferous forests.

Huo H, Feng Q, Su YH - ScientificWorldJournal (2014)

The CCA ordination of 27 plots and environmental variables. Arrows indicate the environmental variables (Ele, elevation; Asp, aspect; Slo, slope; Pos, slope position; BA, basal area; Cov, canopy cover; Den, tree density). Plots dominated by P. crassifolia and S. przewalskii are represented by circles (n = 16) and squares (n = 11), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4109125&req=5

fig1: The CCA ordination of 27 plots and environmental variables. Arrows indicate the environmental variables (Ele, elevation; Asp, aspect; Slo, slope; Pos, slope position; BA, basal area; Cov, canopy cover; Den, tree density). Plots dominated by P. crassifolia and S. przewalskii are represented by circles (n = 16) and squares (n = 11), respectively.
Mentions: In the CCA ordination, a Monte Carlo permutation test indicated that the eigenvalues for the first axis and those for all canonical axes were significant (P < 0.01), revealing that understory species composition was related to the measured variables (Figure 1). The first four axes explained 35.9% of the cumulative variance in species data and 83.3% of the variance in the relationship between understory species composition and environmental variables. CCA results showed that the first axis was significantly associated with elevation (r = −0.775), aspect (r = −0.474), slope (r = −0.464), canopy cover (r = 0.574), basal area (r = 0.467), and tree density (r = 0.607). The second axis was closely correlated with aspect (r = 0.611), slope position (r = 0.378), and SOIL (r = −0.588) (Figure 1; Table 3). Forward selection in the CCA ordination showed that understory species composition was primarily affected by elevation and aspect (P < 0.05; Table 4).

Bottom Line: Many heliophilous species were significantly associated with juniper forest, while only one species was indicative of spruce forest.Using constrained ordination and the variation partitioning model, we quantitatively assessed the relative effects of two sets of explanatory variables on understory species composition.The results showed that topographic variables had higher explanatory power than did site conditions for understory plant distributions.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Ecohydrology of Inland River Basin, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China ; University of Chinese Academy of Sciences, Beijing 100049, China.

ABSTRACT
Understanding the factors that influence the distribution of understory vegetation is important for biological conservation and forest management. We compared understory species composition by multi-response permutation procedure and indicator species analysis between plots dominated by Qinghai spruce (Picea crassifolia Kom.) and Qilian juniper (Sabina przewalskii Kom.) in coniferous forests of the Qilian Mountains, northwestern China. Understory species composition differed markedly between the forest types. Many heliophilous species were significantly associated with juniper forest, while only one species was indicative of spruce forest. Using constrained ordination and the variation partitioning model, we quantitatively assessed the relative effects of two sets of explanatory variables on understory species composition. The results showed that topographic variables had higher explanatory power than did site conditions for understory plant distributions. However, a large amount of the variation in understory species composition remained unexplained. Forward selection revealed that understory species distributions were primarily affected by elevation and aspect. Juniper forest had higher species richness and α-diversity and lower β-diversity in the herb layer of the understory plant community than spruce forest, suggesting that the former may be more important in maintaining understory biodiversity and community stability in alpine coniferous forest ecosystems.

Show MeSH
Related in: MedlinePlus