Carbon cycle terrestrial

The Table of Contents for this collection will facilitate this discussion. Notice that the papers are grouped into the categories of Atmospheric, Aquatic and Terrestrial Components, Global Carbon Cycle and Climate Change, and Global Environmental Science Education. The reader may want to consider the various chemical species studied in each paper. Next, the reader may wish to group the papers by whether they address the source or the receptor, the transport or transformation processes for the chemical species. Finally, the reader needs to establish the time scales and the spatial resolution used. 

Feedbacks may be affected directly by atmospheric CO2, as in the case of possible CO2 fertilization of terrestrial production, or indirectly through the effects of atmospheric CO2 on climate. Furthermore, feedbacks between the carbon cycle and other anthropogenically altered biogeochemical cycles (e.g., nitrogen, phosphorus, and sulfur) may affect atmospheric CO2. If the creation or alteration of feedbacks have strong effects on the magnitudes of carbon cycle fluxes, then projections, made without consideration of these feedbacks and their potential for changing carbon cycle processes, will produce incorrect estimates of future concentrations of atmospheric CO2. 

The most common way in which the global carbon budget is calculated and analyzed is through simple diagrammatical or mathematical models. Diagrammatical models usually indicate sizes of reservoirs and fluxes (Figure 1). Most mathematical models use computers to simulate carbon flux between terrestrial ecosystems and the atmosphere, and between oceans and the atmosphere. Existing carbon cycle models are simple, in part, because few parameters can be estimated reliably. 

Another model, first introduced by Moore, et al. (2i), was used to examine the role of terrestrial vegetation and the global carbon cycle, but did not include an ocean component. This model depended on estimates of carbon pool size and rates of CO2 uptake and release. This model has been used to project the effect of forest clearing and land-use change on the global carbon cycle (22, 23, 24). 

Water and carbon play critical roles in many of the Earth s chemical and physical cycles and yet their origin on the Earth is somewhat mysterious. Carbon and water could easily form solid compounds in the outer regions of the solar nebula, and accordingly the outer planets and many of their satellites contain abundant water and carbon. The type I carbonaceous chondrites, meteorites that presumably formed in the asteroid belt between the terrestrial and outer planets, contain up to 5% (m/m) carbon and up to 20% (m/m) water of hydration. Comets may contain up to 50% water ice and 25% carbon. The terrestrial planets are comparatively depleted in carbon and water by orders of magnitude. The concentration of water for the whole Earth is less that 0.1 wt% and carbon is less than 500 ppm. Actually, it is remarkable that the Earth contains any of these compounds at all. As an example of how depleted in carbon and water the Earth could have been, consider the moon, where indigenous carbon and water are undetectable. Looking at Fig. 2-4 it can be seen that no water- or carbon-bearing solids should have condensed by equilibrium processes at the temperatures and pressures that probably were typical in the zone of fhe solar... 

Schimel, D. S. (1995). Terrestrial ecosystems and the carbon cycle. Glob. Change Biol. 1, 77-91. 

An important example of non-linearity in a biogeochemical cycle is the exchange of carbon dioxide between the ocean surface water and the atmosphere and between the atmosphere and the terrestrial system. To illustrate some effects of these non-linearities, let us consider the simplified model of the carbon cycle shown in Fig. 4-12. Ms represents the sum of all forms of dissolved carbon (CO2, H2CO3, HCOi" and... 

Rainwater and snowmelt water are primary factors determining the very nature of the terrestrial carbon cycle, with photosynthesis acting as the primary exchange mechanism from the atmosphere. Bicarbonate is the most prevalent ion in natural surface waters (rivers and lakes), which are extremely important in the carbon cycle, accoxmting for 90% of the carbon flux between the land surface and oceans (Holmen, Chapter 11). In addition, bicarbonate is a major component of soil water and a contributor to its natural acid-base balance. The carbonate equilibrium controls the pH of most natural waters, and high concentrations of bicarbonate provide a pH buffer in many systems. Other acid-base reactions (discussed in Chapter 16), particularly in the atmosphere, also influence pH (in both natural and polluted systems) but are generally less important than the carbonate system on a global basis. 

Stallard, R. F. (1998). Terrestrial sedimentation and the carbon cycle Coupling weathering and erosion to carbon burial. Glob. Biogeochem. Cycles 12, 231-252. 

Large amounts of carbon are found in the terrestrial ecosystems and there is a rapid exchange of carbon between the atmosphere, terrestrial biota, and soils. The complexity of the terrestrial ecosystems makes any description of their role in the carbon cycle a crude simplification and we shall only review some of the most important aspects of organic carbon on land. Inventories of the total biomass of terrestrial ecosystems have been made by several researchers, a survey of these is given by Ajtay etal.(1979). 

The freshwater cycle is an important link in the carbon cycle as an agent of erosion and as a necessary condition for terrestrial life. Although the amount of carbon stored in freshwater systems is insignificant as a carbon reservoir (De Vooys, 1979 Kempe, 1979a), about 90% of the material transported from land to oceans is carried by streams and rivers. 

The exchange of CO2 between the atmosphere and terrestrial biota is one of the prime links in the global carbon cycle. This is seen by studying the variations of C in the atmosphere. Figure 11-14 presents atmospheric A C for the years... 

There has been a tremendous development of various types of prognostic models of the carbon cycle during the past decades with increased refinement of both oceanic processes (see Siegenthaler and Sarmiento, 1993 Sarmiento et ah, 1992, 1998), terrestrial processes (Bonan,... 

Cao, M. and Woodward, F. I. (1998). Dynamic responses of terrestrial ecosystem carbon cycling to global climate change. Nature 393,249-252. 

Hudson R. J. M. et al. (1994). Modeling the global carbon cycle Nitrogen fertilization of the terrestrial biosphere and the "missing" CO2 sink. Global Bio-geochem. Cycles 8, 307-333. 

Until recently, the distribution of carbon among the different terrestrial spheres was stable. When humans began burning fossil fuels, however, such burning transferred carbon into the atmosphere as CO2. This has become a rapidly changing feature of the overall carbon cycle. Over the last quarter century, the atmospheric concentration of CO2 has grown by more than 10%. 

To solve this problem, we need to make computer calculations on the long-term global carbon cycle including the effect of terrestrial biota, ocean circulation pattern, and metamorphic activities which are not included in Kashiwagi et al. (2000) s computation. 

Soil contributes to a greater extent to total carbon storage than do above-ground vegetation in most forests (Johnson and Curtis 2001). The total amount of soil organic carbon (SOC) in the upper meter of soil is about 1500 x 1015 g C (Eswaran et al. 1993 Batjes 1996), and the global atmospheric pool of CO2 is about 750 x 1015 g C (Harden et al. 1992). The CO2 emission from soil into atmosphere is about 68.0-76.5 1015 g C per year, and this is more than 10 times the CO2 released from fossil fuel combustion (Raich and Potter 1995). Variations in SOC pools and SOM turnover rates, therefore, exert substantial impacts on the carbon cycles of terrestrial ecosystems in terms of carbon sequestration in soil and CO2 emission from soil. 

Steffen W, Noble I, Canadell J, Apps M, Schulze ED, Jarvis PG (1998) The terrestrial carbon cycle implication for the Kyoto protocol. Science 280 1393-1394... 

Cole, J.J. Prairie, Y.T. et al. 2007. Plumbing the global carbon cycle Integrating inland waters into the terrestrial carbon budget. Ecosystems, 10, 171-184. 

Ehleringer JR (1991) 13C/12C fractionation and its utility in terrestrial plant studies. In Coleman DC, Fry B (eds) Carbon isotopic techniques. Academic, New York, pp 187-200 Ehleringer JR, Buchmann RN, Flanagan LB (2000) Carbon isotope ratios in belowground carbon cycle processes. Ecol Appl 10 412-422... 

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