Differences Due to Selection of Field Sites

In general, only limited information is available for ecosystems under naturally or anthropogenically disturbed conditions (e.g., her-bivory, fire, wind-fill, logging, clear-cut, severe air pollution). However, these conditions do not cause disagreements with modeled A, estimates since they are not considered in B10ME3.5 or the other models either. Thus, the lack of predominantly C4 sites could contribute to the observed pattern of lower A. values from the models. 

The B10ME3.5 model may underestimate ecosystem discrimination in places where water stress or environmental limitations on 

It is well established that leaf carbon-isotope discrimination provides valuable information about the ratio of leaf assimilation 

Aj value. Thus, the advantage of the evergreen life form that is well established at the plant and the leaf levels (Aerts, 1995) also shows at the ecosystem level. The model s simulation of leaf area index, which is optimized for A/Gj., is closely correlated to A in most cases, indicating the importance of canopy structure and canopy roughness for determining Aj. (unpublished mss.). 

Site Latitude N/S Longitude E/W A.. [Tool Intercept it T.-rr [%o SE of %o] lime Reference Ufe form 

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