학술논문
Soluble soil aluminum alters the relative uptake of mineral nitrogen forms by six mature temperate broadleaf tree species: possible implications for watershed nitrate retention
Highlighted Student Research
Highlighted Student Research
Document Type
Academic Journal
Source
Oecologia. November 2017, Vol. 185 Issue 3, p327, 11 p.
Subject
Language
English
ISSN
0029-8549
Abstract
Author(s): Mark B. Burnham [sup.1] , Jonathan R. Cumming [sup.1] , Mary Beth Adams [sup.2] , William T. Peterjohn [sup.1] Author Affiliations: (1) Department of Biology, West Virginia University, 0000 [...]
Increased availability of monomeric aluminum (Al.sup.3+) in forest soils is an important adverse effect of acidic deposition that reduces root growth and inhibits nutrient uptake. There is evidence that Al.sup.3+ exposure interferes with NO.sub.3.sup.- uptake. If true for overstory trees, the reduction in stand demand for NO.sub.3.sup.- could increase NO.sub.3.sup.- discharge in stream water. These effects may also differ between species that tolerate different levels of soil acidity. To examine these ideas, we measured changes in relative uptake of NO.sub.3.sup.- and NH.sub.4.sup.+ by six tree species in situ under increased soil Al.sup.3+ using a .sup.15N-labeling technique, and measured soluble soil Al levels in a separate whole-watershed acidification experiment in the Fernow Experimental Forest (WV). When exposed to added Al.sup.3+, the proportion of inorganic N acquired as NO.sub.3.sup.- dropped 14% across species, but we did not detect a reduction in overall N uptake, nor did tree species differ in this response. In the long-term acidification experiment, we found that soluble soil Al was mostly in the free Al.sup.3+ form, and the concentration of Al.sup.3+ was ~65 [mu]M higher (~250%) in the mineral soil of the acidified watershed vs. an untreated watershed. Thus, increased levels of soil Al.sup.3+ under acidic deposition cause a reduction in uptake of NO.sub.3.sup.- by mature trees. When our .sup.15N uptake results were applied to the watershed acidification experiment, they suggest that increased Al.sup.3+ exposure could reduce tree uptake of NO.sub.3.sup.- by 7.73 kg N ha.sup.-1 year.sup.-1, and thus increase watershed NO.sub.3.sup.- discharge.
Increased availability of monomeric aluminum (Al.sup.3+) in forest soils is an important adverse effect of acidic deposition that reduces root growth and inhibits nutrient uptake. There is evidence that Al.sup.3+ exposure interferes with NO.sub.3.sup.- uptake. If true for overstory trees, the reduction in stand demand for NO.sub.3.sup.- could increase NO.sub.3.sup.- discharge in stream water. These effects may also differ between species that tolerate different levels of soil acidity. To examine these ideas, we measured changes in relative uptake of NO.sub.3.sup.- and NH.sub.4.sup.+ by six tree species in situ under increased soil Al.sup.3+ using a .sup.15N-labeling technique, and measured soluble soil Al levels in a separate whole-watershed acidification experiment in the Fernow Experimental Forest (WV). When exposed to added Al.sup.3+, the proportion of inorganic N acquired as NO.sub.3.sup.- dropped 14% across species, but we did not detect a reduction in overall N uptake, nor did tree species differ in this response. In the long-term acidification experiment, we found that soluble soil Al was mostly in the free Al.sup.3+ form, and the concentration of Al.sup.3+ was ~65 [mu]M higher (~250%) in the mineral soil of the acidified watershed vs. an untreated watershed. Thus, increased levels of soil Al.sup.3+ under acidic deposition cause a reduction in uptake of NO.sub.3.sup.- by mature trees. When our .sup.15N uptake results were applied to the watershed acidification experiment, they suggest that increased Al.sup.3+ exposure could reduce tree uptake of NO.sub.3.sup.- by 7.73 kg N ha.sup.-1 year.sup.-1, and thus increase watershed NO.sub.3.sup.- discharge.