Low-impact Systems Research Articles

Diversity of cattle raising systems and its effects over forest regrowth in a core region of cattle production in the Brazilian Amazon

Roughly 60% of all deforested lands in the Brazilian Amazon are covered with pastures, putting cattle raising in evidence as a major driver of deforestation and also of forests’ regrowth. Still, the role of cattle raising diversity in the landscape dynamics of this region remains poorly understood. To contribute to this discussion, we combined data from semi-structured interviews and quantitative spatially explicit methods to characterize and spatialize cattle raising systems and explore the effects of this diversity over secondary vegetation between 2004 and 2014 in Pará, a hotspot of deforestation and core region of cattle production. We quantified the use of different pasture management strategies to classify small- and large-scale operations into systems with high or low impact against pastures’ degradation. High-impact systems were mapped in regions with consolidated infrastructure and high accumulated deforestation, where they expanded. On the contrary, low-impact systems were more widespread and found near forest frontiers, shrinking over time. High-impact systems had less secondary vegetation, while under low-impact systems, as a result of strategies with little or no effect against degradation, the historical pattern of concentration of this cover prevailed. Better infrastructure and access to markets as well as higher accumulated deforestation are underlying conditions related to the emergence of intensification and, as it is still unclear whether intensification is indeed capable of sparing land, the expansion of intensive cattle raising systems has the potential to configure landscapes with reduced forested areas, either primary or secondary.

Mineralogical evidence of unfavorable geochemical interactions between urban runoff pollutants and filter materials in low-impact systems

We report on the geochemical interactions between a synthetic urban runoff (SUR) and the minerals of materials used in a multi-layered column filter (soil, sand, gravel, and tezontle) at the laboratory scale, which mimicked an unvegetated low-impact development (LID) system. After five 8 h infiltration cycles using the SUR, the average concentrations of Pb and Mn decreased slightly at the column outlet, as did HCO3−, SO42-, and Na+, whereas Mg increased and Cl−, Ca2+, and K+ were only detected at the outlet. The filter materials were comprised of silicates, Mn-bearing oxides (hausmannite and manganite), carbonates (calcite), chlorides (sylvite), and sulfates (anglesite, lanarkite, barite, and epsomite). PHREEQC modeling allowed the identification of the geochemical processes that occurred in the filter. The results showed the removal capacity of the filter materials through the formation of secondary minerals such as rhodochrosite (MnCO3) and the over-saturation of anglesite (PbSO4), and also showed that they may mobilize ions from the upper to the interior layers (as Mg2+ from epsomite, MgSO4·7H2O, and Ba2+ from barite, BaSO4). We highlight the importance of knowing the geological nature of filter materials used in LID systems because they may lead to the geogenic mobilization of toxic contaminants to the environment.

Pollinator diversity increases fruit production in Mexican coffee plantations: The importance of rustic management systems

Pollination is an ecological process that provides important services to humans. Pollination service in agroecosystems depends on several factors, including the land management systems used by farmers. Here we focused on the effects of insect pollinator diversity on coffee fruit production along a gradient of management systems in central Veracruz, Mexico. The gradient ranged from low environmental impact management systems (the native forest is not completely removed) to high environmental impact management systems (the native forest is completely removed). We hypothesized that pollinator diversity should be higher in low-impact systems. Then, if fruit production is positively related to pollinator diversity, plantations with low-impact management systems should display higher fruit production than plantations with high-impact management systems. We used observational and experimental data to test this hypothesis. Our results indicated that low-impact management systems have higher species richness and relative diversity (measured with the Shannon-Wiener diversity index) of pollinators than high-impact management systems. In all cases, fruit production was positively related with species richness and diversity of pollinators. Moreover, fruit production was higher in low-impact than in high-impact management systems. These results suggest that the diversity of insect pollinators can be influenced by the management system applied by farmers, and that such effects may have strong consequences on coffee fruit production.