Date of Award

Spring 1995

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Frank P. Day, Jr.

Committee Member

Gerald F. Levy

Committee Member

Kneeland K. Nesius

Call Number for Print

Special Collections LD4331.B47 S74

Abstract

Fine roots play an important role in community development on barrier islands. Fine roots can influence nutrient losses from the soil environment along with regulating water loss based on their distribution and concentration (Nobel et al., 1989; Gleeson and Tilman, 1990). A sequential coring method was used to determine fine root biomass and total biomass along a chronosequence of barrier island dunes and swales on the Virginia Coast Reserve - Long Term Ecological Research Site. Fine root production and the effects of nitrogen fertilization were also examined using an ingrowth core method along the chronosequence. Live fine root biomass, total biomass and fine root production patterns were analyzed. These patterns were associated with topographic position and the interaction with nitrogen, phosphorus and water availability along the chronosequence. Patterns between dunes and swales defined them as two very different community types both structurally and functionally. Dune communities were xeric and swales more mesic in community structure due to their interaction with water table position. The swales had significantly larger accumulations of total biomass (live fine roots, dead fine roots and detrital material) ranging from 59 to 1505 g/m2 and the dunes ranged from 64 to 229 g/m2. The higher biomass quantities were probably due to greater accumulation of detritus resulting from anaerobic conditions in the swales created by a higher water table position. Live fine root biomass changed very little with increases in dune age, 5, 13, 6 and 4 g/m2 for the 6, 24, 36 and 120 yr dunes respectively. But swales showed a general decrease with increased swale age, 180, 105 and 122 g/m2 for the 24, 36 and 120 yr swales respectively. The 6 yr swale did not follow this pattern and had significantly lower biomass than the other swales. Live fine roots and total biomass were concentrated in the upper 10 cm of soil in dune and swale communities across the chronosequence.

Root nitrogen concentration increased with increased age along the dune and swale chronosequence. Root phosphorus concentrations increased with age in the dunes but were not different in the swales. Fine root production increased significantly with N-fertilization in the dune communities, 1.5 times to 2.5 times the control sites. The increased nitrogen levels in the N-fertilized sites were reflected in increased nitrogen concentration in live fine root tissues but root nitrogen levels in the fertilized areas did not increase with increased age; 1798, 1334 and 1826 mg/100g dry wt. for 24, 36 and 120 yr dunes respectively.

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DOI

10.25776/gxk0-db96

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