Decoupled responses of soil bacteria and their invertebrate consumer to warming, but not freeze–thaw cycles, in the Antarctic Dry Valleys

Knox, Matthew A.; Andriuzzi, Walter S.; Buelow, Heather N.; Takacs-Vesbach, Cristina; Adams, Byron J.; Wall, Diana H.

doi:10.1111/ele.12819

Cited by 21 publications

(22 citation statements)

References 64 publications

(150 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Body size distributions may reveal ecological patterns undetected by other analyses (Andriuzzi, Pulleman, Cluzeau, & Pérès, ; Knox et al., ; Lindo, ; Zhao et al., ), but our results show that simpler metrics of abundance and community structure are essential to interpret them correctly. In the high‐OM site, the intercept of the abundance–mass relationship was higher in grazed than ungrazed soil, but rather than a sign of community downsizing (e.g., as in Lindo, ) in this case, it was an artefact of the much lower abundance in grazed than ungrazed Site 3 (i.e., nematodes across the entire size spectrum were less numerous); therefore, we focused on the slopes.…”

Section: Discussioncontrasting

confidence: 62%

“…Such research gaps are particularly wide for soil animals, which is at odds with a growing number of studies on how their body size determines ecosystem processes or responses to global change (de Graaff, Adkins, Kardol, & Throop, 2015;Knox et al, 2017;Lindo, 2015;Moretti et al, 2016). Body size varies enormously in soil fauna, as reflected by the conventional sorting of soil invertebrates in microfauna, mesofauna and macrofauna, of demonstrated functional importance (Cole, Bradford, Shaw, & Bardgett, 2006;de Graaff et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

Andriuzzi

Wall

2018

Journal of Animal Ecology

Self Cite

View full text Add to dashboard Cite

Body size is a central functional trait in ecological communities. Despite recognition of the importance of above ground-below ground interactions, effects of above-ground herbivores on size and abundance-size relationships in soil fauna are almost uncharted. Depending on climate and soil properties, herbivores may increase basal resources of soil food webs, or reduce pore space, mechanisms expected to have contrasting effects on soil animal body size. We investigated how body size and shape of soil nematodes responded to mammalian grazers in three semi-arid grassland sites, along a gradient of soil texture and organic matter (OM) in a long-term herbivore removal study. We analysed nematode mass, length, diameter, body size distribution and biomass distribution. We formulated two mechanistic hypotheses to assess whether resource availability or pore space was the dominant abiotic control and modulated the effects of grazing. In ungrazed soils, average and maximum nematode size, as well as abundance and biomass of large nematodes, were greater in the high-OM than in the low-OM soil, and intermediate in the medium-OM soil. Grazing promoted larger sizes in the low-OM soil, where it had been shown to increase OM and microbial biomass, and led to more homogeneous average size and body size distribution across sites. The results support the hypothesis that nematode size was controlled by basal resource availability rather than by pore space. However, body shape might have been constrained by small pores in the fine-texture, high-OM soil, where nematodes were more elongated. Grazing may facilitate larger sizes in soil nematode communities by boosting basal resources where these are limiting, with important implications for estimations of nematode biomass and contribution to carbon and nutrient cycling. These findings contribute to the insofar-limited mechanistic understanding of how herbivores can shape functional traits of soil fauna and demonstrate that animals at one trophic level may control patterns in body size and abundance-size relationships in other trophic levels without a direct predator prey or competitive linkage between them.

show abstract

Section: Discussioncontrasting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

Andriuzzi

Wall

2018

Journal of Animal Ecology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Field observations and a numerical active layer thermal model are used to elucidate physical controls on the active layer thermodynamic regime. Results of this research refine the Knox et al () hypothesis by clarifying expectations of how regional climate change may alter the frequency, rate, and spatial patterning of active layer freeze‐thaw events. Additionally, field‐observed freezing rates provide a quantitative benchmark for planning future laboratory studies employing cultured nematodes.…”

Section: Introductionsupporting

confidence: 77%

“…Ten‐centimeter freezing rate plotted as a function of 15 day mean antecedent freezable soil moisture at 15 cm. For reference, the freezing rate applied to laboratory cultured S. lindsayae in the Knox et al () study is shown by a black dashed line.…”

Section: Resultsmentioning

confidence: 99%

Soil Moisture Controls the Thermal Habitat of Active Layer Soils in the McMurdo Dry Valleys, Antarctica

2018

View full text Add to dashboard Cite

Antarctic soil ecosystems are strongly controlled by abiotic habitat variables. Regional climate change in the McMurdo Dry Valleys is expected to cause warming over the next century, leading to an increase in frequency of freeze‐thaw cycling in the soil habitat. Previous studies show that physiological stress associated with freeze‐thaw cycling adversely affects invertebrate populations by decreasing abundance and positively selecting for larger body sizes. However, it remains unclear whether or not climate warming will indeed enhance the frequency of annual freeze‐thaw cycling and associated physiological stresses. This research quantifies the frequency, rate, and spatial heterogeneity of active layer freezing to better understand how regional climate change may affect active layer soil thermodynamics, and, in turn, affect soil macroinvertebrate communities. Shallow active layer temperature, specific conductance, and soil moisture were observed along natural wetness gradients. Field observations show that the frequency and rate of freeze events are nonlinearly related to freezable soil moisture (θf). Over a 2 year period, soils at θf < 0.080 m3/m3 experienced between 15 and 35 freeze events and froze rapidly compared to soils with θf > 0.080 m3/m3, which experienced between 2 and 6 freeze events and froze more gradually. A numerical soil thermodynamic model is able to simulate observed freezing rates across a range of θf, reinforcing a well‐known causal relationship between soil moisture and active layer freezing dynamics. Findings show that slight increases in soil moisture can potentially offset the effect of climate warming on exacerbating soil freeze‐thaw cycling.

show abstract

“…For example, increased summer temperatures in the region will initiate more frequent freeze‐thaw cycles in dry soils, increasing mortality of the dominant invertebrate (Knox et al. , ). Snow cover in the McMurdo Dry Valleys is patchy and ephemeral, and soils completely lack plant cover and ecosystem engineering macrofauna, thereby they are devoid of abiotic and biotic buffers that, in other ecosystems, can mitigate the impact of harsh atmospheric conditions (Pauli et al.…”

Section: Discussionmentioning

confidence: 99%

Observed trends of soil fauna in the Antarctic Dry Valleys: early signs of shifts predicted under climate change

Andriuzzi

Adams

Barrett

et al. 2018

Ecology

View full text Add to dashboard Cite

Long-term observations of ecological communities are necessary for generating and testing predictions of ecosystem responses to climate change. We investigated temporal trends and spatial patterns of soil fauna along similar environmental gradients in three sites of the McMurdo Dry Valleys, Antarctica, spanning two distinct climatic phases: a decadal cooling trend from the early 1990s through the austral summer of February 2001, followed by a shift to the current trend of warming summers and more frequent discrete warming events. After February 2001, we observed a decline in the dominant species (the nematode Scottnema lindsayae) and increased abundance and expanded distribution of less common taxa (rotifers, tardigrades, and other nematode species). Such diverging responses have resulted in slightly greater evenness and spatial homogeneity of taxa. However, total abundance of soil fauna appears to be declining, as positive trends of the less common species so far have not compensated for the declining numbers of the dominant species. Interannual variation in the proportion of juveniles in the dominant species was consistent across sites, whereas trends in abundance varied more. Structural equation modeling supports the hypothesis that the observed biological trends arose from dissimilar responses by dominant and less common species to pulses of water availability resulting from enhanced ice melt. No direct effects of mean summer temperature were found, but there is evidence of indirect effects via its weak but significant positive relationship with soil moisture. Our findings show that combining an understanding of species responses to environmental change with long-term observations in the field can provide a context for validating and refining predictions of ecological trends in the abundance and diversity of soil fauna.

show abstract

Decoupled responses of soil bacteria and their invertebrate consumer to warming, but not freeze–thaw cycles, in the Antarctic Dry Valleys

Cited by 21 publications

References 64 publications

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

Soil Moisture Controls the Thermal Habitat of Active Layer Soils in the McMurdo Dry Valleys, Antarctica

Observed trends of soil fauna in the Antarctic Dry Valleys: early signs of shifts predicted under climate change

Contact Info

Product

Resources

About