Response of soil microbial biomass and community composition to chronic nitrogen additions at Harvard forest

Compton, Jana E.; Watrud, Lidia S.; Porteous, Lorna; DeGrood, Shira

doi:10.1016/j.foreco.2004.03.017

Cited by 212 publications

(110 citation statements)

References 59 publications

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“…An alternate explanation for the decreased diversity of the microbial community in conventionally managed soils is that higher inputs of inorganic N in the form of fertilizer led to enrichment of microbial groups that were well suited to high mineral N environments at the expense of other groups. This process has been observed in forest soils [56,57] and could be acting in concert with increased niche diversity in organically managed soil microbial communities to drive diversity differences. The variability of fungi between sample sites within management types ( Fig.…”

Section: Discussionmentioning

confidence: 88%

Agricultural Management and Labile Carbon Additions Affect Soil Microbial Community Structure and Interact with Carbon and Nitrogen Cycling

2013

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We investigated how conversion from conventional agriculture to organic management affected the structure and biogeochemical function of soil microbial communities. We hypothesized the following. (1) Changing agricultural management practices will alter soil microbial community structure driven by increasing microbial diversity in organic management. (2) Organically managed soil microbial communities will mineralize more N and will also mineralize more N in response to substrate addition than conventionally managed soil communities. (3) Microbial communities under organic management will be more efficient and respire less added C. Soils from organically and conventionally managed agroecosystems were incubated with and without glucose ( 13 C) additions at constant soil moisture. We extracted soil genomic DNA before and after incubation for TRFLP community fingerprinting of soil bacteria and fungi. We measured soil C and N pools before and after incubation, and we tracked total C respired and N mineralized at several points during the incubation. Twenty years of organic management altered soil bacterial and fungal community structure compared to continuous conventional management with the bacterial differences caused primarily by a large increase in diversity. Organically managed soils mineralized twice as much NO3 − as conventionally managed ones (44 vs. 23 μg N/g soil, respectively) and increased mineralization when labile C was added. There was no difference in respiration, but organically managed soils had larger pools of C suggesting greater efficiency in terms of respiration per unit soil C. These results indicate that the organic management induced a change in community composition resulting in a more diverse community with enhanced activity towards labile substrates and greater capacity to mineralize N.2

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Section: Discussionmentioning

confidence: 88%

Agricultural Management and Labile Carbon Additions Affect Soil Microbial Community Structure and Interact with Carbon and Nitrogen Cycling

2013

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“…This may not be the case in this study because the P concentration in plant litter also increased concomitantly with N, suggesting the soil P was not as limiting as N. Third, several studies have shown that microbial biomass and microbial activity decrease with the addition of N to soil. For example, Compton et al (2004) found decreased soil microbial biomass and diversity after chronic N additions at Harvard forest. Frey et al (2004) also observed that chronic N additions in a temperate hardwood and pine forest resulted in a decrease in active fungal biomass in fertilized plots, and detected a significant reduction in the activity of the enzyme phenoloxidase, a lignin-degrading enzyme produced by white-rot fungi.…”

Section: Discussionmentioning

confidence: 99%

Litter decomposition and nutrient release as affected by soil nitrogen availability and litter quality in a semiarid grassland ecosystem

et al. 2009

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Nitrogen availability is critically important to litter decomposition, especially in arid and semiarid areas where N is limiting. We studied the relative contributions of litter quality and soil N to litter decomposition of two dominant grassland species, Stipa krylovii and Artemisia frigida, in a semiarid typical steppe ecosystem in Inner Mongolia, China. The study had four different rates of N addition (0, 8, 32, and 64 g N m(-2) year(-1)), and litter samples were decomposed under varying site conditions and by litter types. Litter-mixing effects of the two species were also examined. We found that N addition increased litter N concentration and thus enhanced litter decomposition by improving substrate quality. This increase, however, was offset by the negative effect of increased soil N, resulting in a diminished effect of increased soil N availability on in situ litter decomposition. The positive effects of improved litter quality slightly out-performed the negative effects of increased soil N. Our further analysis revealed that the negative effect of increasing soil N on litter decomposition could be partially explained by reduced soil microbial biomass and activity. Decomposition was significantly faster for litters of a two-species mixture than litters of the single species, but the rate of litter decomposition did not differ much between the two species, suggesting that compositional balance, rather than changes in the dominance between Stipa and Artemisia, is more critical for litter decomposition, hence nutrient cycling in this ecosystem. This semiarid steppe ecosystem may become more conservative in nutrient use with switching of dominance from Artemisia to Stipa with increasing soil N, because Stipa has a slower decomposition rate and a higher nutrient retention rate than Artemisia.

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“…Nested PCR methods were adapted from other nifH gene surveys (Widmer et al 1999;Compton et al 2004), and all methods were tested and modiWed to optimize for DNA concentration, annealing temperature, and for the minimum number of cycles required for successful ampliWcation. The Wrst PCR reactions contained: (1) 23.25 l of nuclease free water (NFW; Burdick and Jackson, Morristown, NJ, USA); (2) 10 l of green GoTaq reaction buVer (Promega, Fitchburg, WI, USA); (3) 2 l of 25 mM MgCl 2 (Promega); (4) 5 l of 2 mM deoxyribonucleotide triphosphates (dNTPs; Promega); (5) 4 l 10 M each of primers nifA (5Ј-GCHWTHTAYG GNAARGNGG) and nifRev (5Ј-GCRTAHABNGCCATC ATYTC) (Operon Biotechnologies, Huntsville, AL, USA); (6) 0.25 l of 5 U GoTaq DNA Polymerase (Promega); and (7) 0.5 l of 10 mg/ml bovine serum albumin (BSA; Promega).…”

Section: Dna Extraction Ampliwcation and Sequencingmentioning

confidence: 99%

Microbial community shifts influence patterns in tropical forest nitrogen fixation

et al. 2010

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The role of biodiversity in ecosystem function receives substantial attention, yet despite the diversity and functional relevance of microorganisms, relationships between microbial community structure and ecosystem processes remain largely unknown. We used tropical rain forest fertilization plots to directly compare the relative abundance, composition and diversity of free-living nitrogen (N)-fixer communities to in situ leaf litter N fixation rates. N fixation rates varied greatly within the landscape, and 'hotspots' of high N fixation activity were observed in both control and phosphorus (P)-fertilized plots. Compared with zones of average activity, the N fixation 'hotspots' in unfertilized plots were characterized by marked differences in N-fixer community composition and had substantially higher overall diversity. P additions increased the efficiency of N-fixer communities, resulting in elevated rates of fixation per nifH gene. Furthermore, P fertilization increased N fixation rates and N-fixer abundance, eliminated a highly novel group of N-fixers, and increased N-fixer diversity. Yet the relationships between diversity and function were not simple, and coupling rate measurements to indicators of community structure revealed a biological dynamism not apparent from process measurements alone. Taken together, these data suggest that the rain forest litter layer maintains high N fixation rates and unique N-fixing organisms and that, as observed in plant community ecology, structural shifts in N-fixing communities may partially explain significant differences in system-scale N fixation rates.

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Response of soil microbial biomass and community composition to chronic nitrogen additions at Harvard forest

Cited by 212 publications

References 59 publications

Agricultural Management and Labile Carbon Additions Affect Soil Microbial Community Structure and Interact with Carbon and Nitrogen Cycling

Agricultural Management and Labile Carbon Additions Affect Soil Microbial Community Structure and Interact with Carbon and Nitrogen Cycling

Litter decomposition and nutrient release as affected by soil nitrogen availability and litter quality in a semiarid grassland ecosystem

Microbial community shifts influence patterns in tropical forest nitrogen fixation

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