Abstract Detail

Recent Topics Posters

Kull, Kathleen [1], Williams, Kimberly [2], Evans, Jonathan [3].

Change in biomass accumulation over thirty-seven years in a nutrient-limited, upland temperate forest.

In forests with a low soil cation exchange capacity, anthropogenic influences can affect patterns of nutrient availability, potentially altering future biomass accumulation and composition.  While alterations such as whole tree removal and acid rain can result in nutrient loss, atmospheric changes in carbon have been shown to increase total biomass aggradation in some forests.  However, we hypothesize that when soil nutrient availability is limited, the effect of elevated carbon levels may be diminished, causing these forests to stop accumulating biomass earlier than would be expected.  Upland forests of the Cumberland Plateau surface are naturally nutrient limited due to their sandstone-derived, porous soils.  Our study site, located in Franklin State Forest (Franklin County, TN, USA), was part of a Tennessee Valley Authority ecosystem study conducted between 1976-1979, which demonstrated that the watershed exhibited a mean net loss of base cations.  Whole tree harvest in this watershed, therefore, likely had the net result of diminishing the total cation pool.  We used 37 years of census data (1977-2015) from a set of 1-ha permanent plots to assess the long term effects of nutrient removal as a result of logging on aboveground biomass aggradation.  Our results showed that the biomass average of three 1-ha plots of live trees increased from 146.6 Mg ha-1 to 229.4 Mg ha-1 from 1977 to 2015 and is best modelled by a polynomial function (R2 = 0.99), suggesting that this stand is no longer aggregating biomass.  Over time, a proportionally larger component of total biomass occurs in trees >30cm DBH (60% in 1978 to 79.4% in 2015), with increases especially notable in A. rubrum (+820%), Liriodendron tulipifera (+360%), Quercus spp. (+117%), and Carya spp. (+31%).  Recruitment of small (<30cm) A. rubrum, Sassafras albidum, Oxydendrum arboreum, and L. tulipifera accounts for ~6.7% of biomass gain, while the largest gains result from growing canopy Quercus species (+35%, +79 Mg ha-1).  Since this stand is reaching a steady-state condition, this confirms our hypothesis that nutrient limited forests may not conform to expectations from other studies which suggest linear biomass gain with elevated carbon.

1 - University of the South, Biology, 735 University Ave, Sewanee, TN, 37383, USA
2 - University of the South, 735 University Ave, Sewanee, TN, 37383, United States
3 - University of the South, 735 University Ave., Sewanee, TN, 37383, USA

Keywords:
biomass
nutrient-limited forest
Cumberland Plateau
Tennessee.

Presentation Type: Recent Topics Poster
Session: P, Recent Topics Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM
Number: PRT025
Abstract ID:1218
Candidate for Awards:None