Legacy effects of a regional drought on aboveground net primary production in six central US grasslands

Griffin‐Nolan, Robert J.; Carroll, Charles J. W.; Denton, Elsie M.; Johnston, Melissa K.; Collins, Scott L.; Smith, Melinda D.; Knapp, Alan K.

doi:10.1007/s11258-018-0813-7

Cited by 82 publications

(75 citation statements)

References 47 publications

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“…Further, in both regions, S was higher postdrought than during the drought. This pattern of grassland biomass being buffered against decreased rainfall and responding strongly to increased rainfall (Knapp et al , Griffin‐Nolan et al ) is consistent with those found in a meta‐analysis of precipitation manipulation experiments (Wilcox et al ), and in cross‐site observational studies (Knapp and Smith , Bai et al ). It is, however, surprising that this holds even in the extreme droughts analyzed in this study (Griffin‐Nolan et al ).…”

Section: Discussionsupporting

confidence: 82%

Nutrient addition increases grassland sensitivity to droughts

Bharath

Borer

Biederman

et al. 2020

Ecology

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Grasslands worldwide are expected to experience an increase in extreme events such as drought, along with simultaneous increases in mineral nutrient inputs as a result of human industrial activities. These changes are likely to interact because elevated nutrient inputs may alter plant diversity and increase the sensitivity to droughts. Dividing a system’s sensitivity to drought into resistance to change during the drought and rate of recovery after the drought generates insights into different dimensions of the system’s resilience in the face of drought. Here, we examine the effects of experimental nutrient fertilization and the resulting diversity loss on the resistance to and recovery from severe regional droughts. We do this at 13 North American sites spanning gradients of aridity, five annual grasslands in California, and eight perennial grasslands in the Great Plains. We measured rate of resistance as the change in annual aboveground biomass (ANPP) per unit change in growing season precipitation as conditions declined from normal to drought. We measured recovery as the change in ANPP during the postdrought period and the return to normal precipitation. Resistance and recovery did not vary across the 400‐mm range of mean growing season precipitation spanned by our sites in the Great Plains. However, chronic nutrient fertilization in the Great Plains reduced drought resistance and increased drought recovery. In the California annual grasslands, arid sites had a greater recovery postdrought than mesic sites, and nutrient addition had no consistent effects on resistance or recovery. Across all study sites, we found that predrought species richness in natural grasslands was not consistently associated with rates of resistance to or recovery from the drought, in contrast to earlier findings from experimentally assembled grassland communities. Taken together, these results suggest that human‐induced eutrophication may destabilize grassland primary production, but the effects of this may vary across regions and flora, especially between perennial and annual‐dominated grasslands.

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Section: Discussionsupporting

confidence: 82%

Nutrient addition increases grassland sensitivity to droughts

Bharath

Borer

Biederman

et al. 2020

Ecology

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“…Evidence shows that lag effects can be attributed to complex interacting feedbacks such as lagged respiration of soil biota, carryover effects of antecedent climate responses (e.g., water deficit), and changes in nutrient cycles [35][36][37][38][39][40] . Variability in lag effects may be particularly significant in waterlimited dryland ecosystems where precipitation events have strong impacts on the variability in aboveground NPP, soil N availability, and drought sensitivity 39 . It was found that lag effects can explain between 18 and 28% of the response variables in semiarid and arid ecosystems 41 .…”

Section: Discussionmentioning

confidence: 99%

Accelerated dryland expansion regulates future variability in dryland gross primary production

et al. 2020

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Drylands cover 41% of Earth's surface and are the largest source of interannual variability in the global carbon sink. Drylands are projected to experience accelerated expansion over the next century, but the implications of this expansion on variability in gross primary production (GPP) remain elusive. Here we show that by 2100 total dryland GPP will increase by 12 ± 3% relative to the 2000-2014 baseline. Because drylands will largely expand into formerly productive ecosystems, this increase in dryland GPP may not increase global GPP. Further, GPP per unit dryland area will decrease as degradation of historical drylands outpaces the higher GPP of expanded drylands. Dryland expansion and climate-induced conversions among sub-humid, semi-arid, arid, and hyper-arid subtypes will lead to substantial changes in regional and subtype contributions to global dryland GPP variability. Our results highlight the vulnerability of dryland subtypes to more frequent and severe climate extremes and suggest that regional variations will require different mitigation strategies.

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“…In the current study, we focus on the legacy effects of the imposed heat and/or drought. While recovery after climate extremes is often fast in temperate grassland (Dreesen et al, 2014 ; Griffin-Nolan et al, 2018 ), the short growing season in the (sub)alpine zone is likely to constrain immediate recovery (De Boeck et al, 2016 ; Cremonese et al, 2017 ). This means that, although short-term responses to heat and drought, both as single factors and in combination, were found to be similar in alpine and temperate grassland, the different recovery dynamics may lead to divergent responses in the longer term.…”

Section: Introductionmentioning

confidence: 99%

Legacy Effects of Climate Extremes in Alpine Grassland

et al. 2018

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Climate change is particularly apparent in many mountainous regions, with warming rates of more than twice the global average being reported for the European Alps. As a result, the probability of climate extremes has increased and is expected to rise further. In an earlier study, we looked into immediate impacts of experimentally imposed heat waves in alpine grassland, and found that these systems were able to cope with heat as long as enough water was available. However, concomitant drought led to increased stress, and reduced aboveground biomass production and green plant cover. Here, we studied the legacy effects (lag-effects) of the imposed climate extreme to see whether delayed responses occurred and how fast the alpine grassland could rebound from the initial changes. Green cover continued to be suppressed the two following years in communities that had been exposed to the most intense hot drought, while aboveground biomass production had returned to control levels by year 2. The initial lower resistance of the forb fraction in the communities was not compensated by faster recovery later on. This resulted in alpine communities that became (and remained) relatively enriched with graminoids, which resisted the original extreme better. The responses of alpine grassland to heat extremes with or without drought observed in this study resemble those typically found in lowland grassland in the short term. However, alpine grassland exhibited longer legacy effects from an annual perspective, with delayed recovery of aboveground production and persistent changes in community composition. This suggests that once initial resistance thresholds are exceeded, impacts may be longer-lasting in alpine grassland, where recovery is constrained by both the short growing season and difficult seedling establishment.

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Legacy effects of a regional drought on aboveground net primary production in six central US grasslands

Cited by 82 publications

References 47 publications

Nutrient addition increases grassland sensitivity to droughts

Nutrient addition increases grassland sensitivity to droughts

Accelerated dryland expansion regulates future variability in dryland gross primary production

Legacy Effects of Climate Extremes in Alpine Grassland

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