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Assessing the sustainability of complex development processes requires multi-causal and integrated analyses. We develop a system-based methodology, rooted Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.in interdisciplinary discussion and consensus building between 15 experts, to construct a multi-causal diagram which examines the sustainability of the Argentine Pampaś process of agriculturization. The resulting diagram includes 25 factors and provides a big-picture of the multiple dimensions and interrelations affecting sustainability. According to this examination, the increasing concentration of production and the incorporation of technological innovations, triggered by economic and institutional factors, are the cause of environmental distresses and social changes, whose consequences for sustainability are still highly disputed. Nevertheless, the symptoms of both environmental and social unsustainability are more evident in the case of the extraPampean regions than in the Pampas. This suggests that the Pampean agriculture model should not be transferred to these regions without substantial modifications. The experts did not reach consensus on whether the agriculturization process is overall sustainable or unsustainable. Lack of consensus revolved mainly around opposing perspectives regarding the significance of the threats to environmental sustainability. The magnitude of socio-distributive unbalance and loss of rural jobs were also contentious. Yet, the paper shows how the exercise of building a joint causal diagram was undoubtedly helpful for linking piece-meal disciplinary facts, brought in from all fronts, into a comprehensive and coherent picture.

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Abstract. In order to test for cumulative effects of fire on Paspalum quadrifarium‐dominated grasslands (‘pajonal’), we analysed the impact of single and repeated fires on the community structure and post‐fire recovery of canopy after a final, simultaneous fire event. Nine plots were defined within a homogeneous pajonal stand, and treatments of low (LF), medium (MF) and high frequency (HF) of fire were defined by the application of one, two or four cold‐season burns, respectively, along a 6‐yr period. Both burned and unburned plots were exposed to grazing by cattle during the summer following the first and the third years of that period. High cattle preference for burned sites conditioned fire temperature and vegetation responses to the following burning events. Cumulative effects between successive burning events were observed for the cover of basal area of the dominant and other sprouting species, the cover and thickness of the litter layer, the seed bank size of the principal recruiter species, and the floristic composition. While light interception by the canopy was positively related to fire frequency during the early growth season, further growth of P. quadrifarium determined a greater light interception in LF than in MF and HF. These patterns of light interception were associated with a faster occupation of the inter‐tussock areas by opportunistic species in plots subjected to frequent fires (HF and MF) than in plots with low fire frequency (LF), and a more lasting regrowth of P. quadrifarium in the LF plot than in the HF ones. High fire frequencies reduced the dominance of P. quadrifarium. Percent of species classified as subordinated graminoids or forbs did not vary among treatments. However, the abundance of different forb species was differentially favoured by contrasting frequencies of fire, describing some coarse relationships between their specific responses and their dispersal strategies.

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