Pastagens enriquecidas com biocarvão: restauro da função de habitat do solo para a resiliência climática e sustentabilidade

One major, if not the main, challenge faced by pastures worldwide is securing aboveground productivity for livestock, while supporting habitat for the functional biodiversity. HABITAT’s working concept is that we can have both, through restoring soils capacity to provide habitat, as a proof of concept. For that, it uses an innovative and synergistic ecosystem engineering approach, consisting of a tailor-made (i.e. site-specific, which will maximise benefits and minimize tradeoffs) combination of biochars and biodiverse seed mixtures (highly nutritious legumes and deep-rooting perennial species) to improve soil attributes that are directly linked to habitat provision. Based on literature and previous work, we hypothesise that biochar will increase vegetation yield by 20-50% [13,24], soil structure and water retention by 10-20% [4], soil NPK by 36%, 34% and 18% respectively [38] and soil organic C stocks by 6.15% [58]. In turn, this is expected to increase germination rates, growth (e.g. through improved ecophysiology, deeper rooting, etc) and functional performance of the selected legumes and perennial wheat, which will then reinforce soil water retention/exchange, livestock nutrition, aboveground food webs by harbouring abundant and diverse pollinator, herbivore and detritivore communities [7] and belowground by promoting microbial activity/diversity, N (up to 4 M/ha) and C (up to 43 Mg/ha OC) fixation [7]. So far, no single scientific approach can fully assess, quantify or monitor soil habitat status in a biodiverse open ecosystem, due to: i) lack of clear/accepted definition of ‘soil habitat function’, ii) low standardization in field biology/ecology methods, and iii) difficulties in addressing spatial and temporal scales because of heterogeneity and variability [34]. In the context of HABITAT, the ‘soil habitat function’ represents our pasture’s capacity to simultaneously, support abundant/diverse/nutritious vegetation cover for livestock and soil conditions that are central for the main representative functional groups of organisms on-site to live, forage, burrow and nidify, under present (i.e. within project life) and future climate-change scenarios. Thus, evaluating the success of our strategy will be done indirectly, by monitoring effects on 4 proxy-attributes that are both, easily quantifiable and directly linked to its habitat provision capacity: 1) moisture retention, 2) biological activity, 3) structure, and 4) nutrients/organic C content [adapted from 34]. Improvements on these proxy attributes will then be used to estimate the overall improvement of SHF, in two ways: by attributing the same weighing to each attribute (i.e. presuming equal contribution to SHF), and by attributing different weighing based on a ‘perceived’ priority scale developed in collaboration with stakeholders. This approach aligns with HABITAT’s aims, as a proof-of-concept, and being a solution-oriented environmental engineering (rather than an ecology) project.