00605nas a2200181 4500008004100000245008700041210006900128300001400197490000700211100002500218700001900243700001600262700002500278700002700303700001500330700002000345856005800365 2022 eng d00aPrecipitation effects on nematode diversity and carbon footprint across grasslands0 aPrecipitation effects on nematode diversity and carbon footprint a2124-21320 v281 aFranco, André, L.C.1 aGuan, Pingting1 aCui, Shuyan1 aTomasel, Cecilia, M.1 aGherardi, Laureano, A.1 aSala, O.E.1 aWall, Diana, H. uhttps://onlinelibrary.wiley.com/doi/10.1111/gcb.1605502584nas a2200217 4500008004100000245010900041210006900150300001100219490000800230520185200238100002602090700002502116700002602141700001602167700002802183700001902211700002702230700002202257700002002279856006702299 2020 eng d00aBody size structure of soil fauna along geographic and temporal gradients of precipitation in grasslands0 aBody size structure of soil fauna along geographic and temporal  a1076380 v1403 a

Precipitation is a global driver of animal abundance and diversity in terrestrial ecosystems, but we know little on how it influences the body size structure of invertebrate communities, particularly soil fauna. It is unclear whether aridity limits the abundance of large-bodied soil invertebrates, and whether temporal precipitation changes can induce local shifts. The potential role of trophic identity in modulating such relationships is also unexplored. Here we investigate the community-weighted mean body mass of soil nematodes, globally widespread invertebrates, in a two-year manipulative experiment with experimental drought and increased rainfall, conducted in three North American grassland ecosystems ranging from arid to semiarid and mesic conditions. We predict that community-weighted mean increases along with precipitation, and that long-term aridity prevents body size shifts in response to within-site temporal changes in precipitation. Nematode community-weighted mean mass increased from arid to mesic conditions. Altered precipitation within sites had much weaker effects, and none detectable in the arid site. When analysing community-weighted mean mass separately by feeding group, only plant-feeding nematodes responded positively to rainfall addition in semiarid and mesic conditions, as well as to ambient interannual differences consistently across sites, presumably due to a tighter ecological linkage with primary production. Our findings point to aridity as an environmental filter against large-bodied soil nematodes, with limited potential for community body size shifts in response to extremely dry or wet years. However, the different responses of plant-feeding taxa from other functional groups indicate potential mismatches between morphologically similar taxa in multitrophic invertebrate communities.

1 aAndriuzzi, Walter, S.1 aFranco, André, L.C.1 aAnkrom, Katharine, E.1 aCui, Shuyan1 ade Tomasel, Cecilia, M.1 aGuan, Pingting1 aGherardi, Laureano, A.1 aSala, Osvaldo, E.1 aWall, Diana, H. uhttps://linkinghub.elsevier.com/retrieve/pii/S003807171930302502650nas a2200277 4500008004100000245010000041210007100141300001400212490000700226520171400233653000901947653002501956653001401981653002801995653002902023653002002052653002202072100002402094700002602118700002402144700001502168700002002183700002302203700001502226856013102241 2017 eng d00aBelow‐ground biological responses to pyrogenic organic matter and litter inputs in grasslands0 aBelow‐ground biological responses to pyrogenic organic matter an a260 - 2690 v313 a

1. Terrestrial ecosystems are often burned by both managed and wildfires. During a fire, the above-ground biomass that would typically accumulate and be decomposed as litter on the soil surface is combusted. Pyrogenic organic matter (PyOM) remaining after a fire is a considerably more recalcitrant organic input to the soil than fresh litter. The activity and community composition of soil organisms responsible for decomposition of organic matter and nutrient recycling in the soil could thus be affected by altered resource availability caused by frequent fires.

2. We examined the effect of PyOM vs. fresh litter inputs to soil biota at both an annually burned and an infrequently burned tallgrass prairie site by tracing (13) C-and N-15-labelled litter and PyOM into growing plant roots, microbial phospholipid fatty acids (PLFAs) and soil nematodes for 1 year.

3. Litter-derived C or N was incorporated into microbes, nematodes and roots, while PyOM contributed minimally to soil microbes and plant roots and was not detectable in nematodes. Soil microbial and nematode abundances in the PyOM amended plots did not significantly differ from the bare soil plots, but nematodes were more abundant and microbial PLFAs less abundant in litter-amended plots. The annually burned site had less predator and omnivore nematodes, with increased abundance of microbial feeders and greater microbial uptake of litter C.

4. An alteration of the soil food web structure caused by burning and the removal of the litter layer, along with the accumulation of non-microbially decomposed PyOM in the soil, contributes to the limitation of N cycling in frequently burned ecosystems.

10afire10alitter decomposition10aNematodes10aphospholipid fatty acid10apyrogenic organic matter10aStable isotopes10atallgrass prairie1 aNicolson, Susan, W.1 aWright, Geraldine, A.1 aSoong, Jennifer, L.1 aDam, Marie1 aWall, Diana, H.1 aCotrufo, Francesca1 aSala, Anna uhttp://knz.lternet.edu/content/below%E2%80%90ground-biological-responses-pyrogenic-organic-matter-and-litter-inputs-grasslands02223nas a2200253 4500008004100000022001400041245009500055210006900150260001600219300001400235490000600249520143500255653002001690653002801710653002801738100001801766700002401784700002301808700002601831700001501857700002001872700002401892856005301916 2015 eng d a1752-089400aFormation of soil organic matter via biochemical and physical pathways of litter mass loss0 aFormation of soil organic matter via biochemical and physical pa cJul-09-2015 a776 - 7790 v83 aSoil organic matter is the largest terrestrial carbon pool1. The pool size depends on the balance between formation of soil organic matter from decomposition of plant litter and its mineralization to inorganic carbon. Knowledge of soil organic matter formation remains limited2 and current C numerical models assume that stable soil organic matter is formed primarily from recalcitrant plant litter3. However, labile components of plant litter could also form mineral-stabilized soil organic matter4. Here we followed the decomposition of isotopically labelled above-ground litter and its incorporation into soil organic matter over three years in a grassland in Kansas, USA, and used laboratory incubations to determine the decay rates and pool structure of litter-derived organic matter. Early in decomposition, soil organic matter formed when non-structural compounds were lost from litter. Soil organic matter also formed at the end of decomposition, when both non-structural and structural compounds were lost at similar rates. We conclude that two pathways yield soil organic matter efficiently. A dissolved organic matter–microbial path occurs early in decomposition when litter loses mostly non-structural compounds, which are incorporated into microbial biomass at high rates, resulting in efficient soil organic matter formation. An equally efficient physical-transfer path occurs when litter fragments move into soil.10aBiogeochemistry10aEnvironmental chemistry10aStable isotope analysis1 aCotrufo, M.F.1 aSoong, Jennifer, L.1 aHorton, Andrew, J.1 aCampbell, Eleanor, E.1 aHaddix, L.1 aWall, Diana, H.1 aParton, William, J. uhttp://www.nature.com/doifinder/10.1038/ngeo252006167nas a2200133 4500008004100000245015200041210006900193260004800262490002200310520562500332100001805957700002005975856003805995 2013 eng d00aThe influence of moisture availability on terrestrial ecosystems: Effects on soil animal communities along a regional/global-scale climate gradient0 ainfluence of moisture availability on terrestrial ecosystems Eff aFort Collins, CObColorado State University0 vPhD. Dissertation3 a

Earth's climate is being altered at an alarming rate, and the consequences of these changes on the planet's ecosystems are unclear. In addition to increased warming due to rising CO2 concentrations, alterations to precipitation patterns will influence soil moisture availability in terrestrial ecosystems and this will have important consequences for plant growth and the ability of soil systems to perform functions such as decomposition and nutrient cycling. The effects on soil systems are especially poorly understood, partly due to the many interactions between environmental conditions and the numerous species found within soil ecosystems, ranging from microbial organisms such as bacteria, archaea and fungi to soil animals including mites and nematodes. With chapter 2, I provide an overview of the role of soil biodiversity and the implications climate and land-use changes may have for ecosystems as a consequence of their effects on soil biodiversity. I then examine the current state of understanding for the influence of soil moisture availability on plant and soil communities of temperate ecosystems in chapter 3, and highlight challenges for future research such as the inclusion of diversity metrics and soil animal community responses in climate change experiments as well as studies that operate at scales larger than single sites in order to better capture the dynamics of ecosystem changes. My research focused on one aspect of climate change, the alteration of soil moisture availability within ecosystems due to changes in precipitation regimes, and whether it affected soil organisms, particularly soil mites and nematodes (Chapter 4 of this dissertation). These two groups were selected because of their high abundances and diversity within soil ecosystems, their dependence upon soil water availability as a consequence of life history traits and their contributions to decomposition and nutrient cycling processes. To examine the effects of changing moisture availability on communities of mites and nematodes I analyzed soil samples along a large scale regional/global climate gradient made up of four long-term ecological research (LTER) sites including Konza Prairie LTER (KNZ), Kansas, Shortgrass Steppe LTER (SGS), Colorado, Jornada Basin LTER (JRN), New Mexico and McMurdo Dry Valleys LTER (MCM), Antarctica. I established elevation transects across hill slopes to obtain landscape-scale gradients of soil moisture availability within each of these ecosystems and sampled existing experimental manipulations of moisture availability from 2009-2011. Mites and nematodes were sorted to trophic groups to determine their ecological role and how changes to their abundances may affect ecosystems. Mite and nematode abundances responded strongly to changes in moisture availability. Across the large-scale climate gradient of all four sites, a positive non-linear response was found with particularly large increases in animal abundances corresponding to incremental moisture increases at the lower limits of moisture availability. Within each of the ecosystems, however, the responses of soil animal trophic group abundances to moisture availability were very similar and were largely negative. In chapter 5 of this dissertation, I further explore the effects of soil moisture and top-down or bottom-up community dynamics on mite and nematode abundances. To do this, I constructed a structural equation model examining the direct and indirect effects of soil moisture availability and trophic interactions on soil animal trophic group abundances. Results of this model suggest that soil moisture strongly controls populations of these organisms. Additionally, predatory mite and nematode trophic groups have top-down controls on lower trophic groups, although these interactions do not appear to be due to predation and instead suggest the influence of additional, unmeasured environmental factors acting indirectly on lower-level soil animal trophic groups. With this dissertation, I demonstrate that changes to soil moisture regimes can have important effects on soil animal communities. A review of the literature (Chapter 3 of this dissertation) showed altered soil moisture availability had the clearest effects on plants, with effects on soil organisms being more idiosyncratic, likely as a result of stronger indirect than direct effects. Experimental evidence along a regional/global climate gradient of two desert and two grassland sites (Chapter 4 of this dissertation) show that increases to moisture availability have strong positive effects on mite and nematode communities, especially at low levels of moisture availability across this large, multi-site scale. At smaller scales (within individual ecosystems) this response becomes weaker and results in declines to animal groups at most sites. These results suggest that as precipitation regimes are altered as a consequence of climate change, the resultant alterations to soil moisture availability may have important feedbacks to terrestrial ecosystems. Observed changes to trophic group structuring in response to changes in moisture availability (Chapters 4 and 5 of this dissertation) show that food webs may be restructured due to future changes in moisture availability, leading to increases to root herbivory and increasing the amount of energy flowing through bacterial rather than fungal decomposition pathways. These changes to food webs can result in alterations to nutrient cycling pathways and shifts in carbon allocation within plant communities, which will further influence ecosystem dynamics.

1 aSylvain, Z.L.1 aWall, Diana, H. uhttp://hdl.handle.net/10217/80184