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Multiple environmental changes drive forest floor vegetation in a temperate mountain forest

View Article: PubMed Central - PubMed

ABSTRACT

Human‐induced changes of the environment and their possible impacts on temperate forest understory plant communities have been examined in many studies. However, the relative contribution of individual environmental factors to these changes in the herb layer is still unclear. In this study, we used vegetation survey data covering a time period of 21 years and collected from 143 permanent plots in the Northern Limestone Alps, Austria. Data on soil chemistry (49 plots), light condition (51 plots), soil temperature and moisture (four and six plots), disturbance (all plots), climate (one station in a clearing area), and airborne sulfur (S) and nitrogen (N) deposition (two forest stands) were available for analyses. We used these data together with plot mean Ellenberg indicator values in a path analysis to attribute their relative contributions to observed vegetation changes. Our analysis reveals a strong directional shift of the forest understory plant community. We found strong evidence for a recovery of the ground‐layer vegetation from acidification as response to decreased S deposition. We did not observe a community response to atmospheric N deposition, but we found a response to altered climatic conditions (thermophilization and drying). The path analysis revealed that changes in the light regime, which were related to small‐scale disturbances, had most influence on herb layer community shifts. Thermophilization and drying were identified as drivers of understory community changes independent of disturbance events.

No MeSH data available.


Results of the nonmetric multidimensional scaling ordination plot (stress = 15.8) based on cover data of vascular plant species in plots (n = 143) of the herb layer: White dots represent the plot data from 1993, black filled triangles those from 2014. The gray paths indicate the movement of plots between the surveys. The 2005 and 2010 plot data were taken as vertices for the paths. The boxplots depict the variance of the survey years 1993 (white) and 2014 (gray). Asterisks symbolize whether there was a significant change in homogeneity of variance (*p < .05, **p < .01, ***p < .001)
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ece32801-fig-0004: Results of the nonmetric multidimensional scaling ordination plot (stress = 15.8) based on cover data of vascular plant species in plots (n = 143) of the herb layer: White dots represent the plot data from 1993, black filled triangles those from 2014. The gray paths indicate the movement of plots between the surveys. The 2005 and 2010 plot data were taken as vertices for the paths. The boxplots depict the variance of the survey years 1993 (white) and 2014 (gray). Asterisks symbolize whether there was a significant change in homogeneity of variance (*p < .05, **p < .01, ***p < .001)

Mentions: The three‐dimensional nMDS ordination explains 79% of the variation of species composition between plots and has a stress value of 0.158 (Figure 4). According to the widely accepted classification of Clarke (1993), nMDS ordinations with stress values <0.2 are considered to deliver an acceptable representation of the original distance matrix. nMDS axis 1 is significantly correlated (p < .05) with all Ellenberg indicator values, nMDS axis 2 with all but N, and nMDS axis 3 with R and L (Table 3). The variance in axis 2 scores decreased significantly (p < .01) from 1993 to 2014. Results of the MANOVA analysis reveal a substantial overall change in species composition (MANOVA without grouping variable: Pillai = 0.123, F3,140 = 6.55, p < .001) and a significant impact of disturbance on the magnitude of this change (MANOVA with disturbance as grouping variable: Pillai = 0.136, F3,139 = 7.28, p < .001).


Multiple environmental changes drive forest floor vegetation in a temperate mountain forest
Results of the nonmetric multidimensional scaling ordination plot (stress = 15.8) based on cover data of vascular plant species in plots (n = 143) of the herb layer: White dots represent the plot data from 1993, black filled triangles those from 2014. The gray paths indicate the movement of plots between the surveys. The 2005 and 2010 plot data were taken as vertices for the paths. The boxplots depict the variance of the survey years 1993 (white) and 2014 (gray). Asterisks symbolize whether there was a significant change in homogeneity of variance (*p < .05, **p < .01, ***p < .001)
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5383490&req=5

ece32801-fig-0004: Results of the nonmetric multidimensional scaling ordination plot (stress = 15.8) based on cover data of vascular plant species in plots (n = 143) of the herb layer: White dots represent the plot data from 1993, black filled triangles those from 2014. The gray paths indicate the movement of plots between the surveys. The 2005 and 2010 plot data were taken as vertices for the paths. The boxplots depict the variance of the survey years 1993 (white) and 2014 (gray). Asterisks symbolize whether there was a significant change in homogeneity of variance (*p < .05, **p < .01, ***p < .001)
Mentions: The three‐dimensional nMDS ordination explains 79% of the variation of species composition between plots and has a stress value of 0.158 (Figure 4). According to the widely accepted classification of Clarke (1993), nMDS ordinations with stress values <0.2 are considered to deliver an acceptable representation of the original distance matrix. nMDS axis 1 is significantly correlated (p < .05) with all Ellenberg indicator values, nMDS axis 2 with all but N, and nMDS axis 3 with R and L (Table 3). The variance in axis 2 scores decreased significantly (p < .01) from 1993 to 2014. Results of the MANOVA analysis reveal a substantial overall change in species composition (MANOVA without grouping variable: Pillai = 0.123, F3,140 = 6.55, p < .001) and a significant impact of disturbance on the magnitude of this change (MANOVA with disturbance as grouping variable: Pillai = 0.136, F3,139 = 7.28, p < .001).

View Article: PubMed Central - PubMed

ABSTRACT

Human&#8208;induced changes of the environment and their possible impacts on temperate forest understory plant communities have been examined in many studies. However, the relative contribution of individual environmental factors to these changes in the herb layer is still unclear. In this study, we used vegetation survey data covering a time period of 21&nbsp;years and collected from 143 permanent plots in the Northern Limestone Alps, Austria. Data on soil chemistry (49 plots), light condition (51 plots), soil temperature and moisture (four and six plots), disturbance (all plots), climate (one station in a clearing area), and airborne sulfur (S) and nitrogen (N) deposition (two forest stands) were available for analyses. We used these data together with plot mean Ellenberg indicator values in a path analysis to attribute their relative contributions to observed vegetation changes. Our analysis reveals a strong directional shift of the forest understory plant community. We found strong evidence for a recovery of the ground&#8208;layer vegetation from acidification as response to decreased S deposition. We did not observe a community response to atmospheric N deposition, but we found a response to altered climatic conditions (thermophilization and drying). The path analysis revealed that changes in the light regime, which were related to small&#8208;scale disturbances, had most influence on herb layer community shifts. Thermophilization and drying were identified as drivers of understory community changes independent of disturbance events.

No MeSH data available.