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

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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.


Boxplots of the deviation of unweighted mean Ellenberg community indicator values of 2005, 2010, and 2014 from the first survey in 1993. The community indicator values represent means of the individual Ellenberg indicator values of each vascular plant species occurring per plot (n = 143). Asterisks symbolize the level of significance (*p < .05, **p < .01, ***p < .001)
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ece32801-fig-0003: Boxplots of the deviation of unweighted mean Ellenberg community indicator values of 2005, 2010, and 2014 from the first survey in 1993. The community indicator values represent means of the individual Ellenberg indicator values of each vascular plant species occurring per plot (n = 143). Asterisks symbolize the level of significance (*p < .05, **p < .01, ***p < .001)

Mentions: Mean herb layer cover decreased from 63.3 ± 30.9% to 52.1 ± 28.4% (p < .001). The total number of vascular plant species occurring in the herb layer of the 143 plots dropped from 235 in 1993 to 207 in 2014. The Sørensen index increased significantly from 0.0023 to 0.0028 (p < .001). The Simpson dissimilarity of the all plots increased significantly from 0.9357 to 0.9373 (p < .001), whereas nestedness decreased from 0.021 to 0.017 (p < .001). All Ellenberg indicator values except for the N value exhibited significant changes between the first and the last survey (Figure 3). Temperature (T) and soil pH (R) values increased, whereas light (L) and soil moisture (F) values decreased.


Multiple environmental changes drive forest floor vegetation in a temperate mountain forest
Boxplots of the deviation of unweighted mean Ellenberg community indicator values of 2005, 2010, and 2014 from the first survey in 1993. The community indicator values represent means of the individual Ellenberg indicator values of each vascular plant species occurring per plot (n = 143). Asterisks symbolize the level of significance (*p < .05, **p < .01, ***p < .001)
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5383490&req=5

ece32801-fig-0003: Boxplots of the deviation of unweighted mean Ellenberg community indicator values of 2005, 2010, and 2014 from the first survey in 1993. The community indicator values represent means of the individual Ellenberg indicator values of each vascular plant species occurring per plot (n = 143). Asterisks symbolize the level of significance (*p < .05, **p < .01, ***p < .001)
Mentions: Mean herb layer cover decreased from 63.3 ± 30.9% to 52.1 ± 28.4% (p < .001). The total number of vascular plant species occurring in the herb layer of the 143 plots dropped from 235 in 1993 to 207 in 2014. The Sørensen index increased significantly from 0.0023 to 0.0028 (p < .001). The Simpson dissimilarity of the all plots increased significantly from 0.9357 to 0.9373 (p < .001), whereas nestedness decreased from 0.021 to 0.017 (p < .001). All Ellenberg indicator values except for the N value exhibited significant changes between the first and the last survey (Figure 3). Temperature (T) and soil pH (R) values increased, whereas light (L) and soil moisture (F) values decreased.

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.