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Castillioni K, Newman GS, Souza L, Iler AM. Effects of drought on grassland phenology depend on functional types. THE NEW PHYTOLOGIST 2022; 236:1558-1571. [PMID: 36068954 DOI: 10.1111/nph.18462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
Shifts in flowering phenology are important indicators of climate change. However, the role of precipitation in driving phenology is far less understood compared with other environmental cues, such as temperature. We use a precipitation reduction gradient to test the direction and magnitude of effects on reproductive phenology and reproduction across 11 plant species in a temperate grassland, a moisture-limited ecosystem. Our experiment was conducted in a single, relatively wet year. We examine the effects of precipitation for species, functional types, and the community. Our results provide evidence that reduced precipitation shifts phenology, alters flower and fruit production, and that the magnitude and direction of the responses depend on functional type and species. For example, early-blooming species shift toward earlier flowering, whereas later-blooming species shift toward later flowering. Because of opposing species-level shifts, there is no overall shift in community-level phenology. This study provides experimental evidence that changes in rainfall can drive phenological shifts. Our results additionally highlight the importance of understanding how plant functional types govern responses to changing climate conditions, which is relevant for forecasting phenology and community-level changes. Specifically, the implications of divergent phenological shifts between early- and late-flowering species include resource scarcity for pollinators and seed dispersers and new temporal windows for invasion.
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Affiliation(s)
- Karen Castillioni
- Oklahoma Biological Survey, University of Oklahoma, Norman, OK, 73019, USA
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
- Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN, 55108, USA
| | - Gregory S Newman
- Oklahoma Biological Survey, University of Oklahoma, Norman, OK, 73019, USA
- Department of Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Lara Souza
- Oklahoma Biological Survey, University of Oklahoma, Norman, OK, 73019, USA
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Amy M Iler
- Chicago Botanic Garden, The Negaunee Institute for Plant Science Conservation and Action, Glencoe, IL, 60022, USA
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Castillioni K, Patten MA, Souza L. Precipitation effects on grassland plant performance are lessened by hay harvest. Sci Rep 2022; 12:3282. [PMID: 35228587 PMCID: PMC8885915 DOI: 10.1038/s41598-022-06961-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 12/24/2021] [Indexed: 11/09/2022] Open
Abstract
Climate and human management, such as hay harvest, shape grasslands. With both disturbances co-occurring, understanding how these ecosystems respond to these combined drivers may aid in projecting future changes in grasslands. We used an experimental precipitation gradient combined with mimicked acute hay harvest (clipping once a year) to examine (1) whether hay harvest influences precipitation effects on plant performance (cover and height) and (2) the role of inter-specific responses in influencing plant performance. We found that hay harvest reduced the strength of precipitation effects on plant performance through changes in bare-ground soil cover. Species performance were mainly influenced by change in abiotic factors, often responding negatively, as hay harvest increased bare-ground amount. Conversely, altered precipitation without hay harvest promoted plant species performance through abiotic factors change first, followed by biotic. Most species, including the dominant grass Schizachyrium scoparium, increased their performance with greater leaf area index (proxy for canopy structure). Our experiment demonstrates that plant performance responds directly to abiotic factors with hay harvest, but indirectly without hay harvest. Positive effects of increasing precipitation were likely due to microhabitat amelioration and resource acquisition, thus inclusion of hay harvest as a disturbance lessens positive impacts of biotic variables on species performance to climate change.
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Frameworks on Patterns of Grasslands’ Sensitivity to Forecast Extreme Drought. SUSTAINABILITY 2020. [DOI: 10.3390/su12197837] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Climate models have predicted the future occurrence of extreme drought (ED). The management, conservation, or restoration of grasslands following ED requires a robust prior knowledge of the patterns and mechanisms of sensitivity—declining rate of ecosystem functions due to ED. Yet, the global-scale pattern of grasslands’ sensitivity to any ED event remains unresolved. Here, frameworks were built to predict the sensitivity patterns of above-ground net primary productivity (ANPP) spanning the global precipitation gradient under ED. The frameworks particularly present three sensitivity patterns that could manipulate (weaken, strengthen, or erode) the orthodox positive precipitation–productivity relationship which exists under non-drought (ambient) condition. First, the slope of the relationship could become steeper via higher sensitivity at xeric sites than mesic and hydric ones. Second, if the sensitivity emerges highest in hydric, followed by mesic, then xeric, a weakened slope, flat line, or negative slope would emerge. Lastly, if the sensitivity emerges unexpectedly similar across the precipitation gradient, the slope of the relationship would remain similar to that of the ambient condition. Overall, the frameworks provide background knowledge on possible differences or similarities in responses of grasslands to forecast ED, and could stimulate increase in conduct of experiments to unravel the impacts of ED on grasslands. More importantly, the frameworks indicate the need for reconciliation of conflicting hypotheses of grasslands’ sensitivity to ED through global-scale experiments.
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