Environmental Controls on Soil and Whole‐ecosystem Respiration from a Tallgrass Prairie

Abstract

piration and heterotrophic microbial respiration. Net ecosystem exchange of CO 2 as an integration of photo-Environmental controls on C cycling in terrestrial ecosystems are synthesis, plant dark respiration, and soil respiration in difficult to define, because (i) C fluxes from plant vs. microbial activity are difficult to separate, and (ii) controlling variables are often inter-grasslands can be obtained with various micrometeorocorrelated. We investigated temporal and spatial determinants of soil logical techniques, which integrate across large land areas respiration and whole-ecosystem respiration using nighttime exposure (Verma, 1990; Norman et al., 1992). Knowing the contriof static chambers to alkali absorption during 2 yr on a tallgrass prairie bution of soil respiration to these fluxes would improve in northeastern Kansas. Soil respiration (mg CO 2-C m Ϫ2 h Ϫ1) was posour understanding of the C cycle and help determine rates itively related to soil organic C (SOC, kg m Ϫ2 0.1 m Ϫ1) through linear of ecosystem C sequestration. Separation of soil resregression [CO 2-C ϭ Ϫ44 ϩ (40 SOC), r 2 ϭ 0.71]. Temporal variations in piration from whole-ecosystem respiration is best suited respiration were related to soil temperature, water-filled pore space during the nighttime, when photosynthetic fixation of (WFPS), and a plant growth rate function, with a combined R 2 of 0.76 CO 2 is not a factor. There is also a need to better underfor soil respiration and of 0.84 for whole-ecosystem respiration. Temstand whole-ecosystem respiration during the nighttime, poral variograms suggested that both soil and whole-ecosystem respiration became increasingly dissimilar the longer the time between mea-since micrometeorological techniques for net ecosystem surements up to 30 d, while dissimilarity in soil temperature and WFPS exchange of CO 2 are generally less suited during the nightleveled between 10 and 20 d of separation. A plant growth rate functime than during the daytime, because of less reliable ention was an important variable that controlled whole-ecosystem respiergy balance, concentration gradients, and wind speeds ration, as well as soil respiration. The ratio of soil respiration to wholeneeded for calculations (Harper, 1989). ecosystem respiration was ≈0.4 during maximum plant growth (July) Previous studies have indicated a high degree of spaand approached a value of 1 during minimal plant growth (November tial and temporal variability in soil respiration that makes to March). We conclude that whole-ecosystem respiration is under simextrapolations of findings to different ecosystems diffiilar environmental controls as soil respiration, the main variables being cult (Buyanovsky et al., 1986; Kiefer, 1990; Rochette et soil organic C, soil temperature, WFPS, and plant growth rate, which al., 1991). Even when attempting to extrapolate results all control the supply of readily mineralizable substrates.

Ecosystem respiration and its components from a Carex meadow of Poyang Lake during the drawdown period

“…The total soil respiration typically contributes 30e80% of annual ecosystem respiration in forests . The Rs to Re ratio in grasslands varied from 0.4 to 1 in a tallgrass prairie (Franzluebbers et al, 2002), and 0.43 to 0.56 in a Tibetan alpine meadow (Zhang et al, 2009). Our estimations in this littoral meadow are within the range observed in Table 2 Ratios of various components to ecosystem respiration and their temperature sensitivities.…”

Partitioning of evapotranspiration and its relation to carbon dioxide exchange in a Chihuahuan Desert shrubland

“…This is especially true for systems dominated by wet-dry cycles where a substantial contribution of soil micro-organisms to the CO 2 efflux is expected (Austin et al, 2004;Huxman et al, 2004a). However, some fraction of efflux should be related to the respiratory activity of plants and correlated with deeper, rooting zone soil moisture and transpiration (Franzluebbers et al, 2002;Chimner and Welker, 2005), and another fraction could be related to the release of CO 2 from the precipitation of carbonates in the soil profile during drying cycles (Emmerich, 2003).…”

Concerning the Measurement and Magnitude of Heat, Water Vapor, and Carbon Dioxide Exchange from a Semiarid Grassland

“…In addition to comparing and reconciling the absolute magnitude of the long-term fluxes measured by each method, we present an analysis of the behavior of the eddy diffusivities for heat, water vapor, and CO 2 . Since grassland ecosystems constitute approximately 24% of the planet's terrestrial surface (Franzluebber et al 2002) or between 32% (3.3 3 10 7 km 2 ) and 40.5% (4.2 3 10 7 km 2 ) of the earth's vegetation cover (Adams et al 1990;White et al 2000;Hunt et al 2002), including nearly 41% of the land cover of the North American continent (Suyker and Verma 2001) and 22% of Europe (Soussana et al 2007), reconciling the two methods could lead to a better understanding of the role of this ubiquitous landscape in the global climate system.…”