ISSN:
1573-5036
Keywords:
carbon sequestration
;
elevated CO2
;
metabolic quotient
;
microbial biomass
;
nutrient limitation
;
respiration
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract We investigated microbial responses in a late successional sedge-dominated alpine grassland to four seasons of CO2 enrichment. Part of the plots received fertilizer equivalent to 4.5g N m−2 a−1. Soil basal respiration (R mic ), the metabolic quotient for CO2 (qCO2=R mic /C mic ), microbial C and N (C mic and N mic ) as well as total soil organic C and N showed no response to CO2 enrichment alone. However, when the CO2 treatment was combined with fertilizer addition R mic and qCO2 were statistically significantly higher under elevated CO2 than under ambient conditions (+57% and +71%, respectively). Fertilizer addition increased microbial N pools by 17%, but this was not influenced by elevated CO2. Microbial C was neither affected by elevated CO2 nor fertilizer. The lack of a CO2-effect in unfertilized plots was suprising in the light of our evidence (based on C balance) that enhanced soil C inputs must have occurred under elevated CO2 regardless of fertilizer treatment. Based on these data and other published work we suggest that microbial responses to elevated CO2 in such stable, late-successional ecosystems are limited by the availability of mineral nutrients and that results obtained with fertile or heavily disturbed substrates are unsuitable to predict future microbial responses to elevated CO2 in natural systems. However, when nutrient limitation is removed (e.g. by wet nitrogen deposition) microbes make use of the additional carbon introduced into the soil system. We believe that the response of natural ecosystems to elevated CO2 must be studied in situ in natural, undisturbed systems.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00010451
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