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Ding L, Li Z, Wang X, Shen B, Xiao L, Dong G, Yu L, Nandintsetseg B, Shi Z, Chang J, Shao C. Spatiotemporal patterns and driving factors of gross primary productivity over the Mongolian Plateau steppe in the past 20 years. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 920:170886. [PMID: 38360323 DOI: 10.1016/j.scitotenv.2024.170886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 12/09/2023] [Accepted: 02/08/2024] [Indexed: 02/17/2024]
Abstract
The Eurasian steppe is the largest temperate grassland in the world. The grassland of the Mongolian Plateau (MP) represents an important part of the Eurasian steppe with high climatic sensitivity. Gross primary productivity (GPP) is a key indicator of the grassland's production, status and dynamic on the MP. In this study, we calibrated and evaluated the grassland-specific light use efficiency model (GRASS-LUE) against the observed GPP collected from nine eddy covariance flux sites on the MP, and compared the performance with other four GPP products (MOD17, VPM, GLASS and GOSIF). GRASS-LUE with higher R2 (0.91) and lower root mean square error (RMSE = 0.99 gC m-2 day-1) showed a better performance compared to the four GPP products in terms of model accuracy and dynamic consistency, especially in typical and desert steppe. The parameters of the GRASS-LUE are more suitable for water-limited grassland could be the reason for its outstanding performance in typical and desert steppe. Mean grassland GPP derived from GRASS-LUE was higher in the east and lower in the west of the MP. Grassland GPP was on average 205 gC m-2 over the MP between 2001 and 2020 with mean annual total GPP of 322 TgC yr-1. 30 % of the MP steppe showed a significant GPP increase. Growing season precipitation is the main factor affecting GPP of the MP steppe across regions. Anthropogenic factors (livestock density and population density) had greater effect on GPP than growing season temperature in pastoral counties in IM that take grazing as one of main industries. These findings can inform the status and trend of the productivity of MP steppe and help government and scientific research institutions to understand the drivers for spatial pattern of grassland GPP on the MP.
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Affiliation(s)
- Lei Ding
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Zhenwang Li
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology, Agricultural College of Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China
| | - Xu Wang
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Beibei Shen
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Liujun Xiao
- National Engineering and Technology Center for Information Agriculture, Engineering Research Center of Smart Agriculture, Ministry of Education, Key Laboratory for Crop System Analysis and Decision Making, Ministry of Agriculture, Jiangsu Key Laboratory for Information Agriculture, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Gang Dong
- School of Life Science, Shanxi University, Taiyuan 030006, China
| | - Lu Yu
- School of Public Affairs, Zhejiang University, Hangzhou 310058, China; German Institute of Development and Sustainability (IDOS), Bonn 53113, Germany
| | - Banzragch Nandintsetseg
- ERDEM Research and Communication Center, Mongolia; Eurasia Institute of Earth Sciences, Istanbul Technical University, Turkey
| | - Zhou Shi
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jinfeng Chang
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
| | - Changliang Shao
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
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2
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Spiess JW, McGranahan DA, Berti MT, Gasch CK, Hovick T, Geaumont B. Spatio-temporal patterns of rangeland forage nutritive value and grazer selection with patch-burning in the US northern Great Plains. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 357:120731. [PMID: 38552513 DOI: 10.1016/j.jenvman.2024.120731] [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: 11/29/2023] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/14/2024]
Abstract
Understanding how management influences forage nutritive value and grazer selection within grazing seasons is an ongoing effort for researchers and land managers globally. We used six, 65 ha pastures managed with patch-burn grazing and stocked with either cow-calf pairs (0.45-0.5 ha • AUM-1) or gestating ewes (0.4-0.48 ha • AUM-1) to explore how patterns in rangeland forage drive grazer selection in semi-arid rangeland over four summer grazing seasons at monthly intervals. We used near-infrared spectroscopy to determine nutritive value parameters from monthly forage clippings. We evaluated livestock performance as the average daily weight gains of each animal. We used mixed-effect models and ordination to compare patch and grazer types across the time-since-fire gradient and found that time-since-fire was significant for all measured variables. Cattle and sheep consistently preferred recently burned patches throughout grazing seasons. These recently burned patches typically contained available forage with higher crude protein and moisture content, lower biomass, and lower acid detergent fiber, acid detergent lignin, and neutral detergent fiber compared to intermediate time since fire patches and patches burned three years ago. Differences between patch-burn grazing with cattle and sheep were observed as additional patch contrasts for available biomass and crude protein, but grazer type and ecological site were not statistically significant factors for the nutritive value ordination. Our study indicates that patch-burn grazing is capable of imposing and maintaining heterogeneous, grazer selection, forage biomass, and nutritive value patterns desirable for heterogeneity focused land management, regardless of grazer type. These findings are especially relevant to the northern Great Plains where introduced grasses are homogenizing the structural environment of remaining rangelands. With prescribed fire currently an uncommon practice throughout the region, these findings provide a baseline of expectations for practitioners and land managers implementing patch-burn grazing and illustrate how grazing livestock can benefit from the patch contrast in forage nutritive value and biomass.
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Affiliation(s)
- Jonathan W Spiess
- USDA Agricultural Research Service, Range Sheep Production Efficiency Research Unit, 27 Office Loop, Dubois, ID, 83423, USA.
| | - Devan Allen McGranahan
- USDA Agricultural Research Service, Livestock & Range Research Laboratory, 234 Ft. Keogh Rd, Miles City, MT, 59301, USA
| | - Marisol T Berti
- North Dakota State University, Plant Sciences, Loftsgard Hall 270A, Fargo, ND, 58105, USA
| | - Caley K Gasch
- Institute of Agriculture, Natural Resources and Extension, University of Alaska Fairbanks, Palmer, AK, 99645, USA
| | - Torre Hovick
- North Dakota State University, Range Science, Fargo, ND, 58105, USA
| | - Benjamin Geaumont
- North Dakota State University, Hettinger Research Extension Center, 102 Highway 12 W, Hettinger, 58639, ND, USA
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Hajek OL, Knapp AK. Signatures of autumn deluges revealed during spring drought in a semi-arid grassland. Oecologia 2024; 204:83-93. [PMID: 38108892 DOI: 10.1007/s00442-023-05488-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 11/08/2023] [Indexed: 12/19/2023]
Abstract
Increases in extremely large precipitation events (deluges) and shifts in seasonal patterns of water availability with climate change will both have important consequences for ecosystem function, particularly in water-limited regions. While previous work in the semi-arid shortgrass steppe of northeastern Colorado has demonstrated this ecosystem's strong sensitivity to growing season deluges, our understanding of ecosystem responses to deluges during the dormant season is limited. Here, we imposed experimental 100 mm deluges (~ 30% of mean annual precipitation) in either September or October in a native C4-dominated shortgrass steppe ecosystem to evaluate the impact of this post-growing season shift in water availability during the autumn and the following growing season. Soil moisture for both deluge treatments remained elevated compared with ambient levels through April as spring precipitation was atypically low. Despite overall low levels of productivity with spring drought, these deluges from the previous autumn increased aboveground net primary production (ANPP), primarily due to increases with C4 grasses. C3 ANPP was also enhanced, largely due to an increase in the annual C3 grass, Vulpia octoflora, in the October deluge treatment. While spring precipitation has historically been the primary determinant of ecosystem function in this ecosystem, this combination of two climate extremes-an extremely wet autumn followed by a naturally-occurring spring drought-revealed the potential for meaningful carryover effects from autumn precipitation. With climate change increasing the likelihood of extremes during all seasons, experiments which create novel climatic conditions can provide new insight into the dynamics of ecosystem functioning in the future.
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Affiliation(s)
- Olivia L Hajek
- Graduate Degree Program in Ecology and Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA.
| | - Alan K Knapp
- Graduate Degree Program in Ecology and Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA
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Zhang Y, Wuriliga, Liu P, Fan R, Guo J, Liu L, Ding Y. Effect of grazing and climatic factors on biodiversity-ecosystem functioning relationships in grassland ecosystems - a case study of typical steppe in Inner Mongolia, China. FRONTIERS IN PLANT SCIENCE 2023; 14:1297061. [PMID: 38186605 PMCID: PMC10770857 DOI: 10.3389/fpls.2023.1297061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 11/22/2023] [Indexed: 01/09/2024]
Abstract
Biodiversity underpins grassland ecological functions and productive capacities. By studying the mechanisms for the maintenance of species diversity in animal communities, we can provide important theoretical guidance for the optimization of grazing management and biodiversity protection. The typical grassland of Xilingol in Inner Mongolia, China, was used as the experimental area, and a grazing intensity experiment was set up. This consisted of four gradient levels that were grazed by sheep, which were available for continuous monitoring, namely control standard sheep unit·day·hectare-1·year-1 (CK, 0 SSU·d·hm-2y-1), light grazing (LG, 170 SSU·d·hm-2·y-1), moderate grazing (MG, 340 SSU·d·hm-2·y-1), and high grazing (HG, 510 SSU·d·hm-2·y-1). Nine consecutive years of multi-indicator monitoring of vegetation was carried out from 2014-2022, using monitoring data coupled with time series and inter-annual climatic (relative moisture index, RMI) fluctuations. This was done to analyze the impacts of disturbances, such as grazing use and climatic fluctuations, on the diversity of species and above-ground productivity of the community, thereby exploring the relationship between diversity and productivity, and provide possible explanations for the emergence of a range of ecological responses. The statistical analysis methods used were One-way Analysis of Variance (ANOVA), general linear regression and mixed-effects models. The main conclusions of this study are as follows: (1) The grassland in the experimental area under CK had the highest diversity and productivity and the ecosystem was better able to buffer the negative impacts of climatic drought. Furthermore, the effect of climate on productivity and diversity weakened as the intensity of grazing increased. (2) LG to MG had a constant diversity. (3) Grazing utilization changed the relationship between community species diversity and aboveground productivity by releasing spatial community resources, altering the structure of plant communities, weakening competitive exclusion, and strengthening complementary effects. However, under all of the conditions there is a brief stage in the time series when diversity is stimulated to increase, and the higher the grazing intensity, the earlier this occurs.
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Affiliation(s)
- Yiran Zhang
- Inner Mongolia Key Laboratory of Grassland Conservation Ecology, Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wuriliga
- Inner Mongolia Key Laboratory of Grassland Conservation Ecology, Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Pengtao Liu
- Inner Mongolia Ecology and Agrometeorology Centre, Hohhot, China
| | - Ruyue Fan
- Inner Mongolia Key Laboratory of Grassland Conservation Ecology, Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Jing Guo
- Inner Mongolia Key Laboratory of Grassland Conservation Ecology, Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Li Liu
- Inner Mongolia Key Laboratory of Grassland Conservation Ecology, Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Yong Ding
- Inner Mongolia Key Laboratory of Grassland Conservation Ecology, Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
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Legesse TG, Dong G, Dong X, Qu L, Chen B, Daba NA, Sorecha EM, Zhu W, Lei T, Shao C. The extreme wet and large precipitation size increase carbon uptake in Eurasian meadow steppes: Evidence from natural and manipulated precipitation experiments. ENVIRONMENTAL RESEARCH 2023; 237:117029. [PMID: 37659645 DOI: 10.1016/j.envres.2023.117029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/04/2023]
Abstract
The distribution of seasonal precipitation would profoundly affect the dynamics of carbon fluxes in terrestrial ecosystems. However, little is known about the impacts of extreme precipitation and size events on ecosystem carbon cycle when compared to the effects of average precipitation amount. The study involved an analysis of carbon fluxes and water exchange using the eddy covariance and chamber based techniques during the growing seasons of 2015-2017 in Bayan, Mongolia and 2019-2021 in Hulunbuir, Inner Mongolia, respectively. The components of carbon fluxes and water exchange at each site were normalized to evaluate of relative response among carbon fluxes and water exchange. The investigation delved into the relationship between carbon fluxes and extreme precipitation over five gradients (control, dry spring, dry summer, wet spring and wet summer) in Hulunbuir meadow steppe and distinct four precipitation sizes (0.1-2, 2-5, 5-10, and 10-25 mm d-1) in Bayan meadow steppe. The wet spring and summer showed the greatest ecosystem respiration (ER) relative response values, 76.2% and 73.5%, respectively, while the dry spring (-16.7%) and dry summer (14.2%) showed the lowest values. Gross primary production (GPP) relative response improved with wet precipitation gradients, and declined with dry precipitation gradients in Hulunbuir meadow steppe. The least value in net ecosystem CO2 exchange (NEE) was found at 10-25 mm d-1 precipitation size in Bayan meadow steppe. Similarly, the ER and GPP increased with size of precipitation events. The structural equation models (SEM) satisfactorily fitted the data (χ2 = 43.03, d.f. = 11, p = 0.215), with interactive linkages among soil microclimate, water exchange and carbon fluxes components regulating NEE. Overall, this study highlighted the importance of extreme precipitation and event size in influencing ecosystem carbon exchange, which is decisive to further understand the carbon cycle in meadow steppes.
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Affiliation(s)
- Tsegaye Gemechu Legesse
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Gang Dong
- School of Life Science, Shanxi University, Taiyuan, 030006, China
| | - Xiaobing Dong
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems (SKLHIGA), College of Ecology, Lanzhou University, Lanzhou, 730000, China
| | - Luping Qu
- Forest Ecology Stable Isotope Center, Forestry College, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Baorui Chen
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Nano Alemu Daba
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Eba Muluneh Sorecha
- State Engineering Laboratory of Efficient Water Use of Crops and Disaster Loss Mitigation/Key Laboratory of Dryland Agriculture, Ministry of Agriculture and Rural Affairs of China, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wen Zhu
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Tinajie Lei
- State Engineering Laboratory of Efficient Water Use of Crops and Disaster Loss Mitigation/Key Laboratory of Dryland Agriculture, Ministry of Agriculture and Rural Affairs of China, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Changliang Shao
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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Zhang Z, Zhang Z, Hautier Y, Qing H, Yang J, Bao T, Hajek OL, Knapp AK. Effects of intra-annual precipitation patterns on grassland productivity moderated by the dominant species phenology. FRONTIERS IN PLANT SCIENCE 2023; 14:1142786. [PMID: 37113592 PMCID: PMC10126275 DOI: 10.3389/fpls.2023.1142786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/23/2023] [Indexed: 06/19/2023]
Abstract
Phenology and productivity are important functional indicators of grassland ecosystems. However, our understanding of how intra-annual precipitation patterns affect plant phenology and productivity in grasslands is still limited. Here, we conducted a two-year precipitation manipulation experiment to explore the responses of plant phenology and productivity to intra-annual precipitation patterns at the community and dominant species levels in a temperate grassland. We found that increased early growing season precipitation enhanced the above-ground biomass of the dominant rhizome grass, Leymus chinensis, by advancing its flowering date, while increased late growing season precipitation increased the above-ground biomass of the dominant bunchgrass, Stipa grandis, by delaying senescence. The complementary effects in phenology and biomass of the dominant species, L. chinensis and S. grandis, maintained stable dynamics of the community above-ground biomass under intra-annual precipitation pattern variations. Our results highlight the critical role that intra-annual precipitation and soil moisture patterns play in the phenology of temperate grasslands. By understanding the response of phenology to intra-annual precipitation patterns, we can more accurately predict the productivity of temperate grasslands under future climate change.
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Affiliation(s)
- Ze Zhang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Inner Mongolia University, Hohhot, China
- Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Zhihao Zhang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Inner Mongolia University, Hohhot, China
- Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Yann Hautier
- Ecology and Biodiversity Group, Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Hua Qing
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Inner Mongolia University, Hohhot, China
- Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Jie Yang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Inner Mongolia University, Hohhot, China
- Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Tiejun Bao
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Inner Mongolia University, Hohhot, China
- Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Olivia L. Hajek
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO, United States
| | - Alan K. Knapp
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO, United States
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Sturchio MA, Macknick JE, Barron‐Gafford GA, Chen A, Alderfer C, Condon K, Hajek OL, Miller B, Pauletto B, Siggers JA, Slette IJ, Knapp AK. Grassland productivity responds unexpectedly to dynamic light and soil water environments induced by photovoltaic arrays. Ecosphere 2022. [DOI: 10.1002/ecs2.4334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Matthew A. Sturchio
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
| | | | - Greg A. Barron‐Gafford
- School of Geography, Development and Environment University of Arizona Tucson Arizona USA
- Biosphere 2 University of Arizona Tucson Arizona USA
| | - Anping Chen
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
| | - Cavin Alderfer
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
| | - Kathleen Condon
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
| | - Olivia L. Hajek
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
| | - Benjamin Miller
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
| | - Benjamin Pauletto
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
| | - J. Alexander Siggers
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
| | - Ingrid J. Slette
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
- Long Term Ecological Research Network, National Center for Ecological Analysis and Synthesis University of California Santa Barbara Santa Barbara California USA
| | - Alan K. Knapp
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
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Fust P, Schlecht E. Importance of timing: Vulnerability of semi-arid rangeland systems to increased variability in temporal distribution of rainfall events as predicted by future climate change. Ecol Modell 2022. [DOI: 10.1016/j.ecolmodel.2022.109961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hoover DL, Hajek OL, Smith MD, Wilkins K, Slette IJ, Knapp AK. Compound hydroclimatic extremes in a semi-arid grassland: Drought, deluge, and the carbon cycle. GLOBAL CHANGE BIOLOGY 2022; 28:2611-2621. [PMID: 35076159 DOI: 10.1111/gcb.16081] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 12/10/2021] [Accepted: 12/10/2021] [Indexed: 05/08/2023]
Abstract
Climate change is predicted to increase the frequency and intensity of extreme events including droughts and large precipitation events or "deluges." While many studies have focused on the ecological impacts of individual events (e.g., a heat wave), there is growing recognition that when extreme events co-occur as compound extremes, (e.g., a heatwave during a drought), the additive effects on ecosystems are often greater than either extreme alone. In this study, we assessed a unique type of extreme-a contrasting compound extreme-where the extremes may have offsetting, rather than additive ecological effects, by examining how a deluge during a drought impacts productivity and carbon cycling in a semi-arid grassland. The experiment consisted of four treatments: a control (average precipitation), an extreme drought (<5th percentile), an extreme drought interrupted by a single deluge (>95th percentile), or an extreme drought interrupted by the equivalent amount of precipitation added in several smaller events. We highlight three key results. First, extreme drought resulted in early senescence, reduced carbon uptake, and a decline in net primary productivity relative to the control treatment. Second, the deluge imposed during extreme drought stimulated carbon fluxes and plant growth well above the levels of both the control and the drought treatment with several additional smaller rainfall events, emphasizing the importance of precipitation amount, event size, and timing. Third, while the deluge's positive effects on carbon fluxes and plant growth persisted for 1 month, the deluge did not completely offset the negative effects of extreme drought on end-of-season productivity. Thus, in the case of these contrasting hydroclimatic extremes, a deluge during a drought can stimulate temporally dynamic ecosystem processes (e.g., net ecosystem exchange) while only partially compensating for reductions in ecosystem functions over longer time scales (e.g., aboveground net primary productivity).
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Affiliation(s)
- David L Hoover
- USDA-ARS Rangeland Resources and Systems Research Unit, Crops Research Laboratory, Fort Collins, Colorado, USA
| | - Olivia L Hajek
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
| | - Melinda D Smith
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
| | - Kate Wilkins
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
| | - Ingrid J Slette
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
| | - Alan K Knapp
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
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Driving Climatic Factors at Critical Plant Developmental Stages for Qinghai–Tibet Plateau Alpine Grassland Productivity. REMOTE SENSING 2022. [DOI: 10.3390/rs14071564] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Determining the driving climatic factors at critical periods and potential legacy effects is crucial for grassland productivity predictions on the Qinghai–Tibet Plateau (QTP). However, studies with limited and ex situ ground samples from highly heterogeneous alpine meadows brought great uncertainties. This study determined the key climatic factors at critical plant developmental stages and the impact of previous plant growth status for interannual aboveground net primary productivity (ANPP) variations in different QTP grassland types. We hypothesize that the impact of climatic factors on grassland productivity varies in different periods and different vegetation types, while its legacy effects are not great. Pixel-based partial least squares regression was used to associate interannual ANPP with precipitation and air temperature at different developmental stages and prior-year ANPP from 2000 to 2019 using remote sensing techniques. Results indicated different findings from previous studies. Precipitation at the reproductive stage (July–August) was the most prominent controlling factor for ANPP which was also significantly affected by precipitation and temperature at the withering (September–October) and dormant stage (November–February), respectively. The influence of precipitation was more significant in alpine meadows than in alpine steppes, while the differentiated responses to climatic factors were attributed to differences in water consumption at different developmental stages induced by leaf area changes, bud sprouting, growth, and protection from frost damage. The prior-year ANPP showed a non-significant impact on ANPP of current year, except for alpine steppes, and this impact was much less than that of current-year climatic factors, which may be attributed to the reduced annual ANPP variations related to the inter-annual carbon circulation of alpine perennial herbaceous plants and diverse root/shoot ratios in different vegetation types. These findings can assist in improving the interannual ANPP predictions on the QTP under global climate change.
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Post AK, Davis KP, LaRoe J, Hoover DL, Knapp AK. Semiarid grasslands and extreme precipitation events: do experimental results scale to the landscape? Ecology 2021; 102:e03437. [PMID: 34133764 DOI: 10.1002/ecy.3437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/18/2021] [Accepted: 05/24/2021] [Indexed: 11/10/2022]
Abstract
The frequency and magnitude of deluges (extremely large rain events) are increasing globally as the atmosphere warms. Small-scale experiments suggest that semiarid grasslands are particularly sensitive to both the timing and size of deluge events. However, the assumption that plot-scale results can be extrapolated across landscapes with variable soil textures, plant communities, and grazing regimes has seldom been tested, despite being key to forecasting regional consequences of precipitation extremes. We used precipitation data from an extensive rain gauge network to identify natural deluges (mean size = 60 ± 31 mm, 1984-2012) that occurred across a ˜60-km2 heterogeneous native shortgrass steppe landscape in Colorado. We then related spatial variation in deluge precipitation to postdeluge responses in canopy greenness (normalized difference vegetation index, NDVI) via satellite imagery. Consistent with results from experiments, this semiarid grassland was most sensitive to mid-growing-season deluges, and postdeluge canopy greenness usually increased linearly (67% of the time) with increasing deluge size. This suggests that aboveground productivity in these semiarid systems will likely increase, rather than asymptote, with forecasted increases in deluge size. Importantly, differences in grazing regime did not significantly alter deluge responses, indicating that these patterns are robust to this widespread management practice.
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Affiliation(s)
- Alison K Post
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, 80523, USA.,Department of Biology, Colorado State University, Fort Collins, Colorado, 80523, USA
| | - Kristin P Davis
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, 80523, USA.,Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, 80523, USA
| | - Jillian LaRoe
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, 80523, USA.,Natural Resources Ecology Laboratory, Colorado State University, Fort Collins, Colorado, 80523, USA
| | - David L Hoover
- U.S. Department of Agriculture-Agricultural Research Service, Rangeland Resources and Systems Research Unit, Crops Research Laboratory, Fort Collins, Colorado, 80526, USA
| | - Alan K Knapp
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, 80523, USA.,Department of Biology, Colorado State University, Fort Collins, Colorado, 80523, USA
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