Fine Root Biomass of Erica Trimera (Engl.) Along An Altitudinal Gradient on Bale Mountains, Ethiopia
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Date
2007-06
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Addis Ababa University
Abstract
The responses of fine roots to a changing environment are suggested to affect the growth and form of an individual plant or the structure and function of forest ecosystems.
The depth-wise distribution and seasonal variation of fine roots of Erica trim era was
investigated at three latitudinal levels, i.e., 3000, 3300 and 3500 mask up to 40 cm depth
separated into three depth classes (0 - 10, 10 - 20 and 20 - 40 cm) using sequential soil
coring. Soil chemical characteristics and moisture were analyzed for all the three
latitudinal levels and depth classes.
Total fine root mass and biomass increased significantly with altitude. Total nitrogen,
available phosphorus, organic carbon, moisture content and pH of the soils increased
significantly with altitude. In the two lower latitudinal levels, 3000 and 3300 mask, fine
root mass and biomass decreased as depth increased, but at the higher altitude (3500
mask) fine roots tended to be more concentrated at the deeper depths. In all of the three
sites the availability of soil nutrients and soil acidity showed a tendency to decrease as
depth increased. The highest fine root mass and biomass was recorded at the major rainy season followed by the transition period, the small rainy season and dry period, in that order.The higher below ground biomass and lower above ground biomass in contrast to higher soil nutrients at higher altitudes suggested that sink limitation may occur at the Americanizations upper latitudinal limit due to the lower temperature. The night frost at higher elevation that is sever above 10 cm in the soil may also be responsible for the limited abundance of fine roots at the depth of 0 - 10 cm than at the two deeper depth classes (10- 20 and 20 - 40 cm). The highest fine root mass during the major rainy season and lowest fine root mass in the dry season indicated that soil moisture was critical in governing the pattern of root growth in these ecosystems. Fine root production increased markedly from35.75 kg ha-1 yr-1 at 3000 malls and 65.37 kg ha-1 yr-1 at 3300 mask to 158.64 kg ha-1 yr-1at 3500 mask. The figures indicate that fine root production and turnover by this specie splays an important role in global carbon sequestration.
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Biology