02579nas a2200397 4500008004100000022001300041245012700054210006900181260001200250300001100262490000600273520134500279653003401624653002501658653003101683653002701714653001801741653001401759100002201773700002401795700002201819700002301841700002301864700001401887700001901901700001601920700002101936700002701957700002601984700001602010700002402026700001602050700002102066700002202087856007202109 2021 eng d a2666900500aPatterns and trends of organic matter processing and transport: Insights from the US Long-term Ecological Research Network0 aPatterns and trends of organic matter processing and transport I c12/2021 a1000250 v23 a

Organic matter (OM) dynamics determine how much carbon is stored in ecosystems, a service that modulates climate. We synthesized research from across the US Long-Term Ecological Research (LTER) Network to assemble a conceptual model of OM dynamics that is consistent with inter-disciplinary perspectives and emphasizes vulnerability of OM pools to disturbance. Guided by this conceptual model, we identified unanticipated patterns and long-term trends in processing and transport of OM emerging from terrestrial, freshwater, wetland, and marine ecosystems. Cross-ecosystem synthesis combined with a survey of researchers revealed several themes: 1) strong effects of climate change on OM dynamics, 2) surprising patterns in OM storage and dynamics resulting from coupling with nutrients, 3) characteristic and often complex legacies of land use and disturbance, 4) a significant role of OM transport that is often overlooked in terrestrial ecosystems, and 5) prospects for reducing uncertainty in forecasting OM dynamics by incorporating the chemical composition of OM. Cross-fertilization of perspectives and approaches across LTER sites and other research networks can stimulate the comprehensive understanding required to support large-scale characterizations of OM budgets and the role of ecosystems in regulating global climate.

10acoupled biogeochemical cycles10across-site synthesis10aorganic matter composition10aorganic matter storage10astabilization10atransport1 aHarms, Tamara, K.1 aGroffman, Peter, M.1 aAluwihare, Lihini1 aCraft, Christopher1 aWieder, William, R1 aHobbie, S1 aBaer, Sara, G.1 aBlair, J.M.1 aFrey, Serita, D.1 aRemucal, Christina, K.1 aRudgers, Jennifer, A.1 aCollins, SL1 aKominoski, John, S.1 aBall, Becky1 aPriscu, John, C.1 aBarrett, John, E. uhttps://www.sciencedirect.com/science/article/pii/S266690052100025303232nas a2200169 4500008004100000245012600041210006900167260001200236300001000248490000600258520266000264100002102924700003302945700002502978700002203003856003703025 2017 eng d00aPrimary productivity as a control over soil microbial diversity along environmental gradients in a polar desert ecosystem0 aPrimary productivity as a control over soil microbial diversity  c07/2017 ae33770 v53 a

Primary production is the fundamental source of energy to foodwebs and ecosystems, and is thus an important constraint on soil communities. This coupling is particularly evident in polar terrestrial ecosystems where biological diversity and activity is tightly constrained by edaphic gradients of productivity (e.g., soil moisture, organic carbon availability) and geochemical severity (e.g., pH, electrical conductivity). In the McMurdo Dry Valleys of Antarctica, environmental gradients determine numerous properties of soil communities and yet relatively few estimates of gross or net primary productivity (GPP, NPP) exist for this region. Here we describe a survey utilizing pulse amplitude modulation (PAM) fluorometry to estimate rates of GPP across a broad environmental gradient along with belowground microbial diversity and decomposition. PAM estimates of GPP ranged from an average of 0.27 mmol O2/m2/s in the most arid soils to an average of 6.97 mmol O2/m2/s in the most productive soils, the latter equivalent to 217 g C/m2/y in annual NPP assuming a 60 day growing season. A diversity index of four carbon-acquiring enzyme activities also increased with soil productivity, suggesting that the diversity of organic substrates in mesic environments may be an additional driver of microbial diversity. Overall, soil productivity was a stronger predictor of microbial diversity and enzymatic activity than any estimate of geochemical severity. These results highlight the fundamental role of environmental gradients to control community diversity and the dynamics of ecosystem-scale carbon pools in arid systems. 

1 aGeyer, Kevin, M.1 aTakacs-Vesbach, Cristina, D.1 aGooseff, Michael, N.1 aBarrett, John, E. uhttps://peerj.com/articles/3377/00595nas a2200169 4500008004100000245008100041210006900122260001200191300001400203490000700217653002100224653001400245100002200259700002300281700002000304856010100324 2008 eng d00aPersistent effects of a discrete climate event on a polar desert ecosystem0 aPersistent effects of a discrete climate event on a polar desert c06/2008 a2249-22610 v1410aClimate Response10anematodes1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/persistent-effects-discrete-climate-event-polar-desert-ecosystem00612nas a2200145 4500008004100000245011000041210006900151260003400220300001100254100001300265700001700278700002200295700002300317856012600340 2006 eng d00aPedogenic carbonate distribution within glacial till in Taylor Valley, Southern Victoria Land, Antarctica0 aPedogenic carbonate distribution within glacial till in Taylor V bGeological Society of America a89-1031 aFoley, K1 aLyons, Berry1 aBarrett, John, E.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/pedogenic-carbonate-distribution-within-glacial-till-taylor-valley-southern-victoria-land00554nas a2200169 4500008004100000245006300041210006200104300001200166490000700178100001500185700001600200700002200216700002000238700002300258700001500281856008800296 2006 eng d00aPhosphorus fractions in soils of Taylor Valley, Antarctica0 aPhosphorus fractions in soils of Taylor Valley Antarctica a806-8150 v701 aBlecker, S1 aIppolito, J1 aBarrett, John, E.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aNorvell, K uhttps://mcm.lternet.edu/content/phosphorus-fractions-soils-taylor-valley-antarctica02635nas a2200181 4500008004100000245007200041210006900113260001200182300001200194490000700206520208100213653001102294100002202305700002302327700002402350700002002374856005902394 2005 eng d00aPotential soil organic matter turnover in Taylor Valley, Antarctica0 aPotential soil organic matter turnover in Taylor Valley Antarcti c02/2005 a108-1170 v373 a

Antarctic Dry Valley ecosystems are among the most inhospitable soil ecosystems on earth with simple food webs and nearly undetectable fluxes of carbon (C) and nitrogen (N). Due to the lack of vascular plants, soil organic matter concentrations are extremely low, and it is unclear how much of the contemporary soil C budget is actively cycling or a legacy of paleolake production and sedimentation. While recent work indicates multiple sources of organic matter for dry valley soils, the composition and kinetics of organic pools remain poorly characterized. We examined soil organic matter pools and potential C and N turnover in soils from within six sites located across three hydrological basins of Taylor Valley, Antarctica that differed in surface age, microclimate and proximity to legacy (paleolake) sources of organic matter. We estimated potential C and N mineralization, and rate kinetics using gas exchange and repeated leaching techniques during 90-d incubations of surface soils collected from valley basin and valley slope positions in three basins of Taylor Valley. Soil organic C content was negatively correlated with the ages of underlying tills, supporting previous descriptions of legacy organic matter. Carbon and N mineralization generally followed 1st order kinetics and were well described by exponential models. Labile pools of C (90 d) were 10% of the total organic C in the upper 5 cm of the soil profile. Labile N was 50% of the total N in surface soils of Taylor Valley. These results show that a large proportion of soil C and particularly N are mineralizable under suitable conditions and suggest that a kinetically defined labile pool of organic matter is potentially active in the field during brief intervals of favorable microclimate. Climate variation changing the duration of these conditions may have potentially large effects on the small pools of C and N in these soils.

10aBiggie1 aBarrett, John, E.1 aVirginia, Ross, A.1 aParsons, Andrew, N.1 aWall, Diana, H. uhttp://instaar.metapress.com/content/e653225425230175/