Journal
BIOGEOCHEMISTRY
Volume 107, Issue 1-3, Pages 379-391Publisher
SPRINGER
DOI: 10.1007/s10533-010-9559-6
Keywords
Denitrification; Uptake; Nutrient retention; Cienega; Paspalum distichum; Regime shift
Funding
- NSF DEB [07142]
- ASU Division of Graduate Studies
Ask authors/readers for more resources
In late-successional steady state ecosystems, plants and microbes compete for nutrients and nutrient retention efficiency is expected to decline when inputs exceed biotic demand. In carbon (C)-poor environments typical of early primary succession, nitrogen (N) uptake by C-limited microbes may be limited by inputs of detritus and exudates derived from contemporaneous plant production. If plants are N-limited in these environments, then this differential limitation may lead to positive relationships between N inputs and N retention efficiency. Further, the mechanisms of N removal may vary as a function of inputs if plant-derived C promotes denitrification. These hypotheses were tested using field surveys and greenhouse microcosms simulating the colonization of desert stream channel sediments by herbaceous vegetation. In field surveys of wetland (ci,nega) and gravelbed habitat, plant biomass was positively correlated with nitrate (NO(3) (-)) concentration. Manipulation of NO(3) (-) in flow-through microcosms produced positive relationships among NO(3) (-) supply, plant production, and tissue N content, and a negative relationship with root:shoot ratio. These results are consistent with N limitation of herbaceous vegetation in Sycamore Creek and suggest that N availability may influence transitions between and resilience of wetland and gravelbed stable states in desert streams. Increased biomass in high N treatments resulted in elevated rates of denitrification and shifts from co-limitation by C and NO(3) (-) to limitation by NO(3) (-) alone. Overall NO(3) (-) retention efficiency and the relative importance of denitrification increased with increasing N inputs. Thus the coupling of plant growth and microbial processes in low C environments alters the relationship between N inputs and exports due to increased N removal under high input regimes that exceed assimilative demand.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available