The responses of alpine grassland to four seasons of CO2 enrichment: a synthesis

Körner, Christian; Diemer, Matthias; Schäppi, Bernd; Niklaus, Pascal A.; Arnone, John A.

doi:10.1016/s1146-609x(97)80002-1

Cited by 110 publications

(90 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4b), i.e., in a range of values where NDVI continues to respond linearly to increasing green biomass and Leaf Area Index (Hmimina et al, 2013). Indeed, many studies have shown that the maximum amount of biomass produced by arctic and alpine species or meadows did not benefit from the experimental lengthening of the favorable period of growth (Kudo et al, 1999;Baptist et al, 2010), or to increasing CO 2 concentrations (Körner et al, 1997). Altogether, these results strongly suggest that intrinsic growth constraints limit the ability of high elevation grasslands to enhance their growth under ameliorated atmospheric conditions.…”

Section: P Choler: Growth Response Of Grasslands To Snow Cover Durationmentioning

confidence: 99%

Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

Choler

2015

Biogeosciences

View full text Add to dashboard Cite

Abstract.A remote sensing approach is used to examine the direct and indirect effects of snow cover duration and weather conditions on the growth response of mountain grasslands located above the tree line in the French Alps. Time-integrated Normalized Difference Vegetation Index (NDVI int ), used as a surrogate for aboveground primary productivity, and snow cover duration were derived from a 13-year long time series of the Moderate-resolution Imaging Spectroradiometer (MODIS). A regional-scale meteorological forcing that accounted for topographical effects was provided by the SAFRAN-CROCUS-MEPRA model chain. A hierarchical path analysis was developed to analyze the multivariate causal relationships between forcing variables and proxies of primary productivity. Inter-annual variations in primary productivity were primarily governed by year-to-year variations in the length of the snow-free period and to a much lesser extent by temperature and precipitation during the growing season. A prolonged snow cover reduces the number and magnitude of frost events during the initial growth period but this has a negligible impact on NDVI int as compared to the strong negative effect of a delayed snow melting. The maximum NDVI slightly responded to increased summer precipitation and temperature but the impact on productivity was weak. The period spanning from peak standing biomass to the first snowfall accounted for two-thirds of NDVI int and this explained the high sensitivity of NDVI int to autumn temperature and autumn rainfall that control the timing of the first snowfall. The ability of mountain plants to maintain green tissues during the whole snowfree period along with the relatively low responsiveness of peak standing biomass to summer meteorological conditions led to the conclusion that the length of the snow-free period is the primary driver of the inter-annual variations in primary productivity of mountain grasslands.

show abstract

Section: P Choler: Growth Response Of Grasslands To Snow Cover Durationmentioning

confidence: 99%

Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

Choler

2015

Biogeosciences

View full text Add to dashboard Cite

show abstract

“…With so few studies, and with so many different experimental methodologies (CO # levels ; study duration ; soil depth sampled ; sampling method ; parameters measured ; Table 1), it is extremely difficult to discern general patterns of CO # response, even with respect to the two most common measures of root response -standing biomass, length or numbers (size) of roots (all 12 studies) ; and root production (five studies). Seven of the 12 studies reported little ( 20%) or no increase in the size of root systems under elevated CO # (C % grasslands : Mo et al, 1992, 0% ;Hunt et al, 1996, 0% ;C $ grassland : Navas et al, 1995, 0% ;Sto$ cklin et al, 1998, 0% ;Leadley et al, 1999, 0%) ;Scha$ ppi &Ko$ rner, 1996 andKo$ rner et al, 1997, j6%, 2-yr mean ;Sindhøj et al, 2000, j12%, 2-yr mean). The average stimulatory response to elevated CO # in these low-responding systems (excluding the C % grassland of Mo et al, 1992 andHunt et al, 1996) is approx.…”

Section: mentioning

confidence: 99%

Dynamics of root systems in native grasslands: effects of elevated atmospheric CO₂

et al. 2000

View full text Add to dashboard Cite

The objectives of this paper were to review the literature on the responses of root systems to elevated CO # in intact, native grassland ecosystems, and to present the results from a 2-yr study of root production and mortality in an intact calcareous grassland in Switzerland. Previous work in intact native grassland systems has revealed that significant stimulation of the size of root systems (biomass, length density or root number) is not a universal response to elevated CO # . Of the 12 studies reviewed, seven showed little or no change in root-system size under elevated CO # , while five showed marked increases (average increase 38%). Insufficient data are available on the effects of elevated CO # on root production, mortality and life span to allow generalization about effects. The diversity of experimental techniques employed in these native grassland studies also makes generalization difficult. In the present study, root production and mortality were monitored in situ in a species-rich calcareous grassland community using minirhizotrons in order to test the hypothesis that an increase in these two measures would help explain the increase in net ecosystem CO # uptake (net ecosystem exchange) previously observed under elevated CO # at this site (600 vs 350 µl CO # l −" ; eight 1.2-m# experimental plots per CO # level using the screen-aided CO # control method). However, results from the first 2 yr showed no difference in overall root production or mortality in the top 18 cm of soil, where 80-90% of the roots occur. Elevated CO # was associated with an upward shift in root length density : under elevated CO # a greater proportion of roots were found in the upper 0-6-cm soil layer, and a lower proportion of roots in the lower 12-18 cm, than under ambient CO # . Elevated CO # was also associated with an increase in root survival probability (RSP ; e.g. for roots still alive 280 d after they were produced under ambient CO # , RSP l 0.30 ; elevated CO # , RSP l 0.56) and an increase (48%) in median root life span in the deepest (12-18 cm) soil layer. The factors driving changes in root distribution and longevity with depth under elevated CO # were not clear, but might have been related to increases in soil moisture under elevated CO # interacting with vertical patterns in soil temperatures. Thus extra CO # taken up in this grassland ecosystem during the growing season under elevated CO # could not be explained by changes in root production and mortality. However, C and nutrient cycling might be shifted closer to the soil surface, which could potentially have a substantial effect on the activities of soil heterotrophic organisms as CO # levels rise.

show abstract

“…Experimental warming in a range of 0.3$6.0°C, for example, significantly increased soil respiration rates by 20% and plant productivity by 19% with considerable variation among individual sites [Rustad et al, 2001]. Meta-analyses of data published in the literature about ecosystems responses to elevated [CO 2 ] revealed a wide range of responses to increases in atmospheric [CO 2 ] [Jastrow et al, 2005;Luo et al, 2006], from no biomass responses in alpine grasslands [Körner et al, 1997] and in the subhumid tall grass prairie for wet years [Owensby et al, 1999], to consistent and substantial production responses in semiarid shortgrass steppe [Morgan et al, 2004]. How to explain the variations in observed terrestrial ecosystem responses to climate change has been a great challenge in the research community.…”

Section: Introductionmentioning

confidence: 99%

Soil hydrological properties regulate grassland ecosystem responses to multifactor global change: A modeling analysis

Weng¹,

Luo²

2008

J. Geophys. Res.

102

View full text Add to dashboard Cite

[1] We conducted a modeling study to evaluate how soil hydrological properties regulate water and carbon dynamics of grassland ecosystems in response to multifactor global change. We first calibrated a process-based terrestrial ecosystem (TECO) model against data from two experiments with warming and clipping or doubled precipitation in Great Plains. The calibrated model was used to simulate responses of soil moisture, evaporation, transpiration, runoff, net primary production (NPP), ecosystem respiration (R h ), and net ecosystem production (NEP) to changes in precipitation amounts and intensity, increased temperature, and elevated atmospheric [CO 2 ] along a soil texture gradient (sand, sandy loam, loam, silt loam, and clay loam). Soil available water capacity (AWC), which is the difference between field capacity and wilting point, was used as the index to represent soil hydrological properties of the five soil texture types. Simulation results showed that soil AWC altered partitioning of precipitation among runoff, evaporation, and transpiration, and consequently regulated ecosystem responses to global environmental changes. The fractions of precipitation that were used for evaporation and transpiration increased with soil AWC but decreased for runoff. High AWC could greatly buffer water stress during long drought periods, particularly after a large rainfall event. NPP, R h , and NEP usually increased with AWC under ambient and 50% increased precipitation scenarios. With the halved precipitation amount, NPP, R h , and NEP only increased from 7% to 7.5% of AWC followed by declines. Warming and CO 2 effects on soil moisture, evapotranspiration, and runoff were magnified by soil AWC. Regulatory patterns of AWC on responses of NPP, R h , and NEP to warming were complex. In general, CO 2 effects on NPP, R h , and NEP increased with soil AWC. Our results indicate that variations in soil texture may be one of the major causes underlying variable responses of ecosystems to global changes observed from different experiments.Citation: Weng, E., and Y. Luo (2008), Soil hydrological properties regulate grassland ecosystem responses to multifactor global change: A modeling analysis,

show abstract

The responses of alpine grassland to four seasons of CO2 enrichment: a synthesis

Cited by 110 publications

References 18 publications

Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

Dynamics of root systems in native grasslands: effects of elevated atmospheric CO₂

Soil hydrological properties regulate grassland ecosystem responses to multifactor global change: A modeling analysis

Contact Info

Product

Resources

About

The responses of alpine grassland to four seasons of CO2 enrichment: a synthesis

Cited by 110 publications

References 18 publications

Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

Dynamics of root systems in native grasslands: effects of elevated atmospheric CO2

Soil hydrological properties regulate grassland ecosystem responses to multifactor global change: A modeling analysis

Contact Info

Product

Resources

About

Dynamics of root systems in native grasslands: effects of elevated atmospheric CO₂