TY - JOUR
T1 - Influence of nitrite accumulation in association with seasonal patterns and mineralization of soil nitrogen in a semi-arid pine forest
AU - Gelfand, Ilya
AU - Yakir, Dan
N1 - Funding Information:
We are grateful to Uri Shapira, Boaz Arad, and Nitai Zecharia for technical assistance, to Dr. Sharon Avrahami and Dr. Dror Minz for useful discussions. This research was supported in part by GLOWA-Jordan River, the Israeli Ministry of Science and Technology (MOS), the Israeli Ministry of the Environment, the Sussman Family Center for the Study of Environmental Sciences, The Henry Gutwirth Fund for Research, and the Philip M. Klutznick Fund for Research.
PY - 2008/2/1
Y1 - 2008/2/1
N2 - To identify factors that influence the relatively high productivity of a semi-arid pine afforestation system in southern Israel, we investigated inorganic nitrogen deposition and mineralization for more than 2 years. To this end, we measured bulk and dry deposition, in situ N-mineralization over the seasonal cycle, and the potential activity of nitrifying microorganisms by soil slurry incubations. There was a small increase in bulk N deposition in the forest, compared with shrubland, but no change in dry deposition. An unexpected rapid increase in nitrite concentration in the forest soil was observed after soil rewetting by the first winter rains, which could not be explained by deposition. This was accompanied by a decrease in ammonium and only a slight increase in nitrate concentrations. Only a small increase in nitrite and a rapid increase in nitrate concentration in the mineral soil were observed in the surrounding shrubland. Soil slurry incubations from the forest sites exhibited significant delay in nitrite, compared with nitrate accumulation (up to 50 h under lab conditions) in samples taken in the dry season, but not in the wet season. This indicated different rates of ammonium and nitrite oxidation that are most likely linked to differential activation of different microbial populations after the summer stress. The initial oxidation process of ammonia to nitrate, upon soil rewetting in semi-arid environments, appears to occur as a partially uncoupled two-step process, as opposed to a rapid continuous one in wetter environments. This may have implications for the synchronization of nitrate availability to plants and therefore for high forest productivity and nitrogen use efficiency. Forest productivity in the semi-arid regions, in turn, is becoming increasingly more important with persistent predictions of warming and drying trends over the entire Mediterranean basin and other regions.
AB - To identify factors that influence the relatively high productivity of a semi-arid pine afforestation system in southern Israel, we investigated inorganic nitrogen deposition and mineralization for more than 2 years. To this end, we measured bulk and dry deposition, in situ N-mineralization over the seasonal cycle, and the potential activity of nitrifying microorganisms by soil slurry incubations. There was a small increase in bulk N deposition in the forest, compared with shrubland, but no change in dry deposition. An unexpected rapid increase in nitrite concentration in the forest soil was observed after soil rewetting by the first winter rains, which could not be explained by deposition. This was accompanied by a decrease in ammonium and only a slight increase in nitrate concentrations. Only a small increase in nitrite and a rapid increase in nitrate concentration in the mineral soil were observed in the surrounding shrubland. Soil slurry incubations from the forest sites exhibited significant delay in nitrite, compared with nitrate accumulation (up to 50 h under lab conditions) in samples taken in the dry season, but not in the wet season. This indicated different rates of ammonium and nitrite oxidation that are most likely linked to differential activation of different microbial populations after the summer stress. The initial oxidation process of ammonia to nitrate, upon soil rewetting in semi-arid environments, appears to occur as a partially uncoupled two-step process, as opposed to a rapid continuous one in wetter environments. This may have implications for the synchronization of nitrate availability to plants and therefore for high forest productivity and nitrogen use efficiency. Forest productivity in the semi-arid regions, in turn, is becoming increasingly more important with persistent predictions of warming and drying trends over the entire Mediterranean basin and other regions.
KW - Ammonium
KW - Mediterranean climate
KW - Nitrate
KW - Nitrification
KW - Nitrite
KW - Nitrogen deposition
KW - Pine forest
KW - Semi-arid
UR - http://www.scopus.com/inward/record.url?scp=36048966591&partnerID=8YFLogxK
U2 - 10.1016/j.soilbio.2007.09.005
DO - 10.1016/j.soilbio.2007.09.005
M3 - Article
AN - SCOPUS:36048966591
SN - 0038-0717
VL - 40
SP - 415
EP - 424
JO - Soil Biology and Biochemistry
JF - Soil Biology and Biochemistry
IS - 2
ER -
