Causes and consequences of liana infestation in southern Amazonia

1. Lianas, a key component of tropical forests, can limit growth of trees, impacting both the structure and functioning of forests, and are expected to benefit from fragmentation and potentially from global climatic changes. While it is critical to understand the impacts of liana infestation on contemporary tropical forests across large geographical areas, to date most liana studies have been focussed on single or few sites. 2. We measured and quantified liana infestation of 16,066 trees with diameter ≥10 cm in 27 plots distributed across southern Amazonia, a region characterized by substantial ecological and environmental variation and environmental change. We examined the influence of potential drivers of liana infestation at the plot, species and individual tree level. Additionally, we evaluated the effect of liana infestation on tree growth. 3. More than half of all trees had lianas in their crown. At the plot level, infestation by lianas was driven by forest structure but not by the studied climate or soil fertility variables, though low levels of liana infestation were found in seasonally flooded forests. 4. At the tree level, larger and stouter trees had a greater proportion of their crown infested with lianas. At the species level, trees belonging to intrinsically slow‐growing, dense‐wooded species were more susceptible to liana infestation. 5. Liana infestation had a negative impact on tree growth, with growth of heavily infested trees reduced by 33% compared to non‐infested. The impact of liana infestation on tree growth was strongest for the best‐lit tree crowns, indicating that lianas act to reduce the large competitive advantage that well‐lit trees otherwise hold over their neighbours. 6. Synthesis. Lianas are a pervasive and influential feature of the extensive forests at the southern edge of Amazonia. The degree of liana infestation in forests was closely linked to species‐level variables such as potential growth and wood density as well as the size of the individual tree. The growth of heavily infested trees was particularly restricted by lianas, and especially so for trees growing in otherwise favourable conditions, indicating the potential for lianas not only to reduce forest growth rates overall, but also to modify competitive hierarchies among trees within tropical forests

Fire, deforestation, and livestock: when the smoke clears

Recent Amazon fires fuelled a media narrative combining politics with an already emotive story linking deforestation to extensive cattle ranching and global meat consumption. Scrutiny of the reasons for the 2019 fires suggests that the perceived link between deforestation and extensive land use for beef production is not as clear as commonly supposed. Indeed, land sparing through sustainable intensification of predominant livestock pastures may be acting as a significant buffer between meat demand and livestock production and consequent land use change and deforestation. Well-intentioned beef boycotts potentially weaken the incentive to invest in pasture restoration and may lead to a counterfactual of extensive land use, and increased greenhouse gas emissions. The possibility suggests the need for more nuanced debate about the regional-specificity of land use for sustainable livestock production, and the role of dietary change

Achieving low-carbon cattle ranching in the Amazon:‘Pasture sudden death’ as a window of opportunity

Livestock farming is the key sector that can most contribute to low-carbon agriculture in the Amazon, the region of Brazil that stands most to gain from land-use intensification and most to lose from further primary habitat loss. Cattle pastures affected by the ‘sudden death’ syndrome, which has decimated exotic grass pastures across seven Amazonian states, have forced cattle ranchers to begin renewing their grazing lands. Vast areas of pasture die-off create an opportunity to catalyse livestock intensification through public policies. More productive livestock husbandry results in avoided deforestation, mitigation of methane emissions from enteric digestion, and the release of vast previously deforested areas to either more intensive agriculture or forest restoration. This, however, comes with a cautionary note as the much debated promising paradigm of agricultural intensification remains largely untested as a land-sparing strategy across the humid tropics. Well-designed government subsidies will, therefore, be required to ensure that thousands of landowners can take advantage of this opportunity with minimal environmental side effects

Loss of secondary-forest resilience by land-use intensification in the Amazon

Summary: Understanding how land-use intensification affects forest resilience is a key for elucidating the mechanisms underlying regeneration processes and for planning more sustainable land-use systems. Here, we evaluate how the intensification of a swidden cultivation system affects secondary-forest resilience in the Amazon. Along a gradient of land-use intensity, we analysed the relative role of management intensity, soil properties and landscape configuration in determining the resilience of early secondary forests (SFs). We assessed resilience as the recovery level of forest structure and species diversity achieved by SFs 5 years after abandonment. We used as a reference the recovery level achieved by SFs subjected to the lowest intensity of use, given that these SFs are part of a dynamic system and may not develop to old-growth forests. Therefore, we interpreted a deviation from this reference level as a change in forest resilience. The recovery of forest structure was determined by management intensity, while the recovery of species diversity was driven by landscape configuration. With increasing number of cycles and weeding frequency along with decreasing fallow period and patch area, SF basal area and canopy height decreased, regeneration shifted from a seed- to sprout-dependent strategy, and liana infestation on trees increased. With decreasing area covered by old-growth forest, species richness and Shannon diversity decreased. Secondary-forest resilience decreased with land-use intensification, mainly mediated by the effect of management intensity upon regeneration strategies. Our findings demonstrate the - many times overlooked - importance of previous management intensity in determining the structure of SFs and highlight the importance of regeneration strategy for forest resilience. Synthesis. Swidden cultivation supports people's livelihoods and transforms landscapes in the tropics. The sustainability of this system depends on ecosystem services provided by SFs that develop during the fallow period. Land-use intensification reduces the resilience of SFs and ultimately may drive the system towards an arrested succession state that holds a lower potential to deliver ecosystem services to the Amazonian people. Under an intensification scenario, the adaptation of management practices is needed to guarantee the resilience of swidden cultivation systems. Swidden cultivation supports people's livelihoods and transforms landscapes in the tropics. We evaluated how the intensification of this system affects secondary-forest resilience in the Amazon. Secondary-forest resilience decreased with land-use intensification, mainly mediated by the effect of management intensity upon regeneration strategies. Under an intensification scenario, the adaptation of management practices is needed to guarantee the resilience of swidden cultivation. © 2015 The Authors. Journal of Ecology © 2015 British Ecological Society

The negative influences of the new brazilian forest code on the conservation of riparian forests

More than one million hectares of riparian forests were degraded or altered in Mato Grosso State (Brazil) up to 2009. The aim of the research is to set a comparative scenario to show differences in the quantification of environmental liabilities in riparian forest areas resulting from the change in native vegetation protection rules due to the transition between Laws 4771/65 and 12651/2012. Data collection took place in a marginal stretch of Vermelho River in Rondonópolis County, Mato Grosso State. The following data set was taken into consideration: aerial images derived from unmanned aerial vehicle, Rapid Eye satellite images and orbital images hosted at Google Earth. The spatial resolution of those images was compared. The aerial photos composed a mosaic that was photo-interpreted to generate land use and occupation classes. The riparian forest areas of a rural property were used as parameter, and their environmental situation was compared in 05 meter and 100 meter strips. Thus, by taking into consideration the current rules, 23,501 m2 of area ceased to be an environmental liability within the riparian forest and became a consolidated rural area. According to the previous Forest Code, in a different scenario, that is, in a set of rural properties, the public authority would receive USD 68,600.00 in fines. The new Brazilian Forestry Code of 2012, which replaces the previous one made in 1965, exempts those responsible for rural property from regenerating previously deforested native vegetation — an obligation established by older Forest Code. We have shown that the new Forest Code has diminished the legal responsibility of the rural owners in relation to the maintenance of forest fragments in their properties