Diverse responses of phenology to global changes in a grassland ecosystem (original) (raw)
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New Phytologist, 2008
Flowering is a critical stage in plant life cycles, and changes might alter processes at the species, community and ecosystem levels. Therefore, likely flowering-time responses to global change drivers are needed for predictions of global change impacts on natural and managed ecosystems. • Here, the impact of elevated atmospheric CO 2 concentration ([CO 2 ]) (550 µmol mol −1 ) and warming (+2ºC) is reported on flowering times in a native, species-rich, temperate grassland in , Australia in both 2004 and 2005. • Elevated [CO 2 ] did not affect average time of first flowering in either year, only affecting three out of 23 species. Warming reduced time to first flowering by an average of 19.1 d in 2004, acting on most species, but did not significantly alter flowering time in 2005, which might be related to the timing of rainfall. Elevated [CO 2 ] and warming treatments did not interact on flowering time. • These results show elevated [CO 2 ] did not alter average flowering time or duration in this grassland; neither did it alter the response to warming. Therefore, flowering phenology appears insensitive to increasing [CO 2 ] in this ecosystem, although the response to warming varies between years but can be strong. MH et al. 1999. Responses of tundra plants to experimental warming: Meta-analysis of the international tundra experiment. Ecological Monographs 69: 491-511. Badeck FW, Bondeau A, Bottcher K, Doktor D, Lucht W, Schaber J, Sitch S. 2004. Responses of spring phenology to climate change. New Phytologist 162: 295-309. Beaubien EG, Hall-Beyer M. 2003. Plant phenology in western Canada: trends and links to the view from space. Ecological Monitoring and Assessment 88: 419-429. Brando P, Ray D, Nepstad D, Cardinot G, Curran LM, Oliveira R. 2006. Effects of partial throughfall exclusion on the phenology of Coussarea racemosa (Rubiaceae) in an east-central Amazon rainforest. Oecologia 150: 181-189. Brearley FQ, Proctor J, Suriantata, Nagy L, Dalrymple G, Voysey BC. 2007. Reproductive phenology over a 10-yr period in a lowland evergreen rain forest of central borneo. Journal of Ecology 95: 828-839. Buchanan AM. 1999. A census of the vascular plants of Tasmania. Hobart, Australia: Tasmanian Herbarium. Cipollini ML, Drake BG, Whigham D. 1993. Effects of elevated CO 2 on growth and carbon/nutrient balance in the deciduous woody shrub Lindera benzoin (L.) blume (Lauraceae). Oecologia 96: 339-346. Cleland EE, Chiariello NR, Loarie SR, Mooney HA, Field CB. 2006.
2010
Future climate scenarios predict simultaneous changes in environmental conditions, but the impacts of multiple climate change drivers on ecosystem structure and function remain unclear. We used a novel experimental approach to examine the responses of an upland grassland ecosystem to the 2080 climate scenario predicted for the study area (3.5°C temperature increase, 20% reduction in summer precipitation, atmospheric CO 2 levels of 600 ppm) over three growing seasons. We also assessed whether patterns of grassland response to a combination of climate change treatments could be forecast by ecosystem responses to single climate change drivers. Effects of climate change on aboveground production showed considerable seasonal and interannual variation; April biomass increased in response to both warming and the simultaneous application of warming, summer drought, and CO 2 enrichment, whereas October biomass responses were either non-significant or negative depending on the year. Negative impacts of summer drought on production were only observed in combination with a below-average rainfall regime, and showed lagged effects on spring biomass. Elevated CO 2 had no significant effect on aboveground biomass during this study. Both warming and the 2080 climate change scenario were associated with a significant advance in flowering time for the dominant grass species studied. However, flowering phenology showed no significant response to either summer drought or elevated CO 2 . Species diversity and equitability showed no response to climate change treatments throughout this study. Overall, our data suggest that single-factor warming experiments may provide valuable information for projections of future ecosystem changes in cool temperate grasslands.
Climate change has induced pronounced shifts in the reproductive phenology of plants, with the timing of first flowering advancing in most species. Indeed, population persistence may be threatened by the inability to track climate change phenologically. Nevertheless, substantial variation exists in biological responses to climate change across taxa. Here, we explore the consequences of climate change for flowering phenology by integrating data from a long-term observational study and a manipulative experiment under contemporary conditions. Dissecting the environmental factors that influence phenological change will illuminate why interspecific variation exists in responses to climate change. We examine a 43-year record of first flowering for six species in subalpine meadows of Colorado in conjunction with a 3-year snow manipulation experiment on the perennial mustard Boechera stricta from the same site. We analyze shifts in the onset of flowering in relation to environmental drivers...
GRASSLAND RESPONSES TO THREE YEARS OF ELEVATED TEMPERATURE, CO 2 , PRECIPITATION, AND N DEPOSITION
Ecological Monographs, 2003
Global climate and atmospheric changes may interact in their effects on the diversity and composition of natural communities. We followed responses of an annual grassland to three years of all possible combinations of experimentally elevated CO 2 (ϩ300 L/L), warming (ϩ80 W/m 2 , ϩϳ1ЊC), nitrogen deposition (ϩ7 g N·m Ϫ2 ·yr Ϫ1 ), and precipitation (ϩ50%). Responses of the 10 most common plant species to global changes and to interannual variability were weak but sufficiently consistent within functional groups to drive clearer responses at the functional group level. The dominant functional groups (annual grasses and forbs) showed distinct production and abundance responses to individual global changes. After three years, N deposition suppressed plant diversity, forb production, and forb abundance in association with enhanced grass production. Elevated precipitation enhanced plant diversity, forb production, and forb abundance but affected grasses little. Warming increased forb production and abundance but did not strongly affect diversity or grass response. Elevated CO 2 reduced diversity with little effect on relative abundance or production of forbs and grasses. Realistic combinations of global changes had small diversity effects but more marked effects on the relative dominance of forbs and grasses. The largest change in relative functional group abundance (ϩ50% forbs) occurred under the combination of elevated CO 2 ϩ warming ϩ precipitation, which will likely affect much of California in the future. Strong interannual variability in diversity, individual species abundances, and functional group abundances indicated that in our system, (1) responses after three years were not constrained by lags in community response, (2) individual species were more sensitive to interannual variability and extremes than to mean changes in environmental and resource conditions, and (3) simulated global changes interacted with interannual variability to produce responses of varying magnitude and even direction among years. Relative abundance of forbs, the most speciose group in the community, ranged after three years from Ͼ30% under elevated CO 2 ϩ warming ϩ precipitation to Ͻ12% under N deposition. While opposing production responses at the ecosystem level by different functional groups may buffer responses such as net primary production (NPP) change, these shifts in relative dominance could influence ecosystem processes such as nutrient cycling and NPP via differences between grasses and forbs in tissue chemistry, allocation, phenology, and productivity.
Five years of phenology observations from a mixed-grass prairie exposed to warming and elevated CO2
Scientific Data, 2016
Atmospheric CO 2 concentrations have been steadily increasing since the Industrial Era and contribute to concurrent increases in global temperatures. Many observational studies suggest climate warming alone contributes to a longer growing season. To determine the relative effect of warming on plant phenology, we investigated the individual and joint effects of warming and CO 2 enrichment on a mixed-grass prairie plant community by following the development of six common grassland species and recording four major life history events. Our data support that, in a semi-arid system, while warming advances leaf emergence and flower production, it also expedites seed maturation and senescence at the species level. However, the additive effect can be an overall lengthening of the growing and reproductive seasons since CO 2 enrichment, particularly when combined with warming, contributed to a longer growing season by delaying plant maturation and senescence. Fostering synthesis across multiple phenology datasets and identifying key factors affecting plant phenology will be vital for understanding regional plant community responses to climate change. Design Type(s) time series design • parallel group design Measurement Type(s) life cycle stage • climate data • volumetric soil water Technology Type(s) phenological observation • meteorological station • water content profile probe Factor Type(s) atmospheric carbon dioxide • air temperature Sample Characteristic(s) State of Wyoming • prairie • Artemisia frigida • Bouteloua gracilis • Hesperostipa comata • Koeleria macrantha • Pascopyrum smithii • Sphaeralcea coccinea
Proceedings of the National Academy of Sciences, 2003
Biodiversity responses to ongoing climate and atmospheric changes will affect both ecosystem processes and the delivery of ecosystem goods and services. Combined effects of co-occurring global changes on diversity, however, are poorly understood. We examined plant diversity responses in a California annual grassland to manipulations of four global environmental changes, singly and in combination: elevated CO 2, warming, precipitation, and nitrogen deposition. After 3 years, elevated CO2 and nitrogen deposition each reduced plant diversity, whereas elevated precipitation increased it and warming had no significant effect. Diversity responses to both single and combined global change treatments were driven overwhelmingly by gains and losses of forb species, which make up most of the native plant diversity in California grasslands. Diversity responses across treatments also showed no consistent relationship to net primary production responses, illustrating that the diversity effects of these environmental changes could not be explained simply by changes in productivity. In twoto four-way combinations, simulated global changes did not interact in any of their effects on diversity. Our results show that climate and atmospheric changes can rapidly alter biological diversity, with combined effects that, at least in some settings, are simple, additive combinations of single-factor effects.
PLoS ONE, 2012
Background: The longer growing season under climate warming has served as a crucial mechanism for the enhancement of terrestrial carbon (C) sink over the past decades. A better understanding of this mechanism is critical for projection of changes in C cycling of terrestrial ecosystems. Methodology/Principal Findings: A 4-year field experiment with day and night warming was conducted to examine the responses of plant phenology and their influences on plant coverage and ecosystem C cycling in a temperate steppe in northern China. Greater phenological responses were observed under night than day warming. Both day and night warming prolonged the growing season by advancing phenology of early-blooming species but without changing that of lateblooming species. However, no warming response of vegetation coverage was found for any of the eight species. The variances in species-level coverage and ecosystem C fluxes under different treatments were positively dependent upon the accumulated precipitation within phenological duration but not the length of phenological duration. Conclusions/Significance: These plants' phenology is more sensitive to night than day warming, and the warming effects on ecosystem C exchange via shifting plant phenology could be mediated by precipitation patterns in semi-arid grasslands.
Ecological Monographs, 2003
We integrated experimental and natural gradient field methods to investigate effects of climate change and variability on flowering phenology of 11 subalpine meadow shrub, forb, and graminoid species in Gunnison County, Colorado (USA). At a subalpine meadow site, overhead electric radiant heaters advanced snowmelt date by 16 d and warmed and dried soil during the growing season. At three additional sites, a snow removal manipulation advanced snowmelt date by 7 d without altering growing season soil microclimate. We compared phenological responses to experimental climate change with responses to natural microclimate variability across spatial gradients at small and landscape scales, as well as across a temporal gradient from a separate study.