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Harvard Forest Data Archive
Thresholds and Regime Shifts at Four LTER Sites (CCE, JRN, PAL, SBC) 1951-2009Related Publications
- hf170-01: krill (preview)
- hf170-02: penguins (preview)
- hf170-03: cucumbers (preview)
- hf170-04: pastures (preview)
- hf170-05: R code for exploratory data analysis for threshold detection
- Lead: Brandon Bestelmeyer, Aaron Ellison
- Investigators: Edward Brinton, William Fraser, Sally Holbrook, Mark Ohman, Donna Patterson-Fraser, Andrew Rassweiler, Russell Schmitt
- Contact: Aaron Ellison
- Start date: 1951
- End date: 2009
- Status: completed
- Location: CCE-LTER, JRN-LTER, PAL-LTER, SBC-LTER
- Latitude: -64.8 to +34.5
- Longitude: -121.8 to -64.0
- Elevation: -210 to 1320 meter
- Taxa: Aristida spp., Bouteloua eriopoda (black grama grass), Nyctiphanes simplex (krill), Pachythyone rubra (aggregating red sea cucumber), Pygoscelis adeliae (adelie penguin), Pygoscelis antarctica (chinstrap penguin), Pygoscelis papua (gentoo penguin), Sporobolus spp.
- Release date: 2011
- EML file: knb-lter-hfr.170.9
- DOI: digital object identifier
- Related links:
- California Current Ecosystem LTER
- Jornada Basin LTER
- Pacific Decadal Oscillation (PDO)
- Palmer Station Antarctica LTER
- Santa Barbara Coastal LTER
- Study type: long-term measurement
- Research topic: physiological ecology, population dynamics and species interactions
- LTER core area: populations
- Keywords: ecosystems, population dynamics, thresholds
The existence and causes of abrupt transitions, thresholds, or regime shifts between ecosystem states is of great concern because the likelihood of such transitions is predicted to increase. The science for measuring and responding to state changes, however, is not well developed. This limitation stems from a lack of data-supported case studies of abrupt transitions in all but a few well-studied ecosystems. We used 30-60 years of data on biological responses and putative drivers from ocean, coastal, polar, and dryland ecosystems to illustrate general approaches to analysis of abrupt transitions. The analyses indicate one case in which the state or response variable (krill abundance) tracked abrupt changes in the driver (Pacific Decadal Oscillation) in a linear fashion. Response variables in other cases (sea cucumber abundance, penguin abundance, and perennial grass production) exhibited hysteretic relationships to drivers (wave intensity, sea ice duration, and monsoonal rainfall amounts, respectively) through a variety of response mechanisms. The analyses illustrate that 1) a suite of common concepts and approaches can be used across disparate systems, 2) there are generally insufficient data for the use of leading indicators, particularly considering the abruptness of transition relative to the lifespan of long-lived organisms, 3) information on spatiotemporal context is useful for comparing transitions in similar systems, and 4) ancillary information from associated experiments and observations is critical for interpreting response-driver relationships.
For detailed methods, please see: (1) Brinton, E., Townsend, A., 2003. Decadal variability in abundances of the dominant euphausiid species in southern sectors of the California Current. Deep-Sea Research Part II 50: 2469-2492. (2) Lavaniegos, B.E., Ohman, M.D., 2007. Coherence of long-term variations of zooplankton in two sectors of the California Current System. Progress in Oceanography 75: 42-69. (3) Ohman, M.D., Smith, P.E., 1995. A comparison of zooplankton sampling methods in the CalCOFI time series. California Cooperative Oceanic Fisheries Investigations Reports 36: 153-158.
For detailed methods, please see: http://pal.lternet.edu.
Sea cucumber project
For detailed methods, please see: Rassweiler A., R. J. Schmitt, and S. J. Holbrook SJ. 2010. Triggers and maintenance of multiple shifts in the state of a natural community. Oecologia 164:489-498.
Black grama grass project
For detailed methods, please see: http://jornada-www.nmsu.edu.
This dataset is released to the public under Creative Commons license CC BY (Attribution). Please keep the designated contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement.
Bestelmeyer B, Ellison A. 2011. Thresholds and Regime Shifts at Four LTER Sites (CCE, JRN, PAL, SBC) 1951-2009. Harvard Forest Data Archive: HF170.
- year: sample year (1951-2009)
- pdo.index: Pacific Decadal Oscillation index. Values from http://jisao.washington.edu/pdo/ (unit: dimensionless / missing value: NA)
- n.sim: abundance of Nyctiphanes simplex; values are log10 of actual abundance values (unit: dimensionless / missing value: NA)
- year: sample year (1974-2010)
- adelies: number of nesting Adelie penguins (unit: number / missing value: NA)
- chinstraps: number of nesting Chinstrap penguins (unit: number / missing value: NA)
- gentoos: number of nesting Gentoo penguins (unit: number / missing value: NA)
- ice.days: estimated duration of sea ice in days (unit: number / missing value: NA)
- year: year sampling occurred (1982-2010)
- p.rub: percent cover of Pachythyone rubra (unit: dimensionless / missing value: NA)
- wave.days: number of days with large waves (defined as days with maximum significant wave height above 3.25 m) (unit: number / missing value: NA)
- year: year of data (1938-1971)
- p2.yield: estimated annual net primary productivity for pasture 2 (unit: poundPerAcre / missing value: NA)
- p9.yield: estimated annual net primary productivity for pasture 9 (unit: poundPerAcre / missing value: NA)
- js.precip: rainfall at the West Well rain gauge, located between pastures 2 and 9 (unit: inch / missing value: NA)
hf170-05: R code for exploratory data analysis for threshold detection
- Format: R code
- Type: R code