Event Title

Weakened Biotic-Environmental Relationships in the Herb Layer After a Hundred Years of Recovery From Logging Disturbance

Event Website

http://www.nafew2009.org/

Start Date

24-6-2009 9:40 AM

End Date

24-6-2009 10:00 AM

Description

A central debate in community ecology has been the degree to which communities bear the mark of history in their composition and structure. Modern forests have unique species compositions that are decoupled from gradients of temperature, precipitation, and soil types. We do not know how long it takes for the relationship between species composition and the environment to return. The intensity of disturbance may effect the time it takes for environmental coupling to return. Previous studies have addressed environmental coupling on former agriculture land. In contrast, logging disturbance has a lesser impact on the environment and has affected more of the Eastern North American landscape. Given that logging is a lower intensity disturbance than agriculture and that these communities have had a century of recovery time, does environmental coupling play an equal role in old growth and previously logged forests? This study was conducted on the understory herbaceous community of old growth and hundred year old rich cove hardwood forests in the Nantahala National Forest, North Carolina. Herbaceous diversity and abundance along with 24 environmental variables and a spatial dataset based on principal coordinates of neighbor matrices (PCNM) were used in a partial canonical correspondence analysis (CCA). The results show that understory herbs in old growth forests have a strong biotic-environmental relationship. However, this relationship is decoupled in hundred year old forests. The environmental model explained 37.2% of the variation in species composition in old growth forests with Mn, Mg and total exchangeable cations significant predictors. In hundred year old forests, Zn was a significant predictor, but it only explained 11.1% of the variation in community composition. Logging disturbance a century ago retains a mark on species composition by decoupling the biotic-environmental relationship. A hundred years of recovery is inadequate for species to reach equilibrium with the environment.

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Jun 24th, 9:40 AM Jun 24th, 10:00 AM

Weakened Biotic-Environmental Relationships in the Herb Layer After a Hundred Years of Recovery From Logging Disturbance

A central debate in community ecology has been the degree to which communities bear the mark of history in their composition and structure. Modern forests have unique species compositions that are decoupled from gradients of temperature, precipitation, and soil types. We do not know how long it takes for the relationship between species composition and the environment to return. The intensity of disturbance may effect the time it takes for environmental coupling to return. Previous studies have addressed environmental coupling on former agriculture land. In contrast, logging disturbance has a lesser impact on the environment and has affected more of the Eastern North American landscape. Given that logging is a lower intensity disturbance than agriculture and that these communities have had a century of recovery time, does environmental coupling play an equal role in old growth and previously logged forests? This study was conducted on the understory herbaceous community of old growth and hundred year old rich cove hardwood forests in the Nantahala National Forest, North Carolina. Herbaceous diversity and abundance along with 24 environmental variables and a spatial dataset based on principal coordinates of neighbor matrices (PCNM) were used in a partial canonical correspondence analysis (CCA). The results show that understory herbs in old growth forests have a strong biotic-environmental relationship. However, this relationship is decoupled in hundred year old forests. The environmental model explained 37.2% of the variation in species composition in old growth forests with Mn, Mg and total exchangeable cations significant predictors. In hundred year old forests, Zn was a significant predictor, but it only explained 11.1% of the variation in community composition. Logging disturbance a century ago retains a mark on species composition by decoupling the biotic-environmental relationship. A hundred years of recovery is inadequate for species to reach equilibrium with the environment.

http://digitalcommons.usu.edu/nafecology/sessions/recovery/3