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Charcoal fragments preserved in soils or sediments are used by scientists to reconstruct fire histories and thereby improve our understanding of past vegetation dynamics and human-plant relationships. Unfortunately, most published methods for charcoal extraction and analysis are incompletely described and are therefore difficult to reproduce. To improve the standardization and replicability of soil charcoal analysis, as well as to facilitate accessibility for non-experts, we developed a detailed, step-by-step protocol to isolate charcoal from soil and to efficiently count and measure charcoal fragments. The extraction phase involves the chemical soaking and wet sieving of soils followed by the collection of macrocharcoal (≥500 μm). The analysis phase is performed semi-automatically using the open-source software ImageJ to count and measure the area, length, and width of fragments from light stereo microscope images by means of threshold segmentation. The protocol yields clean charcoal fragments, a set of charcoal images, and datasets containing total charcoal mass, number of fragments, and morphological measurements (area, length, and width) for each sample. We tested and validated the protocol on 339 soil samples from tropical savannas and forests in eastern lowland Bolivia. We hope that this protocol will be a valuable resource for scientists in a variety of fields who currently study, or wish to study, macroscopic charcoal in soils as a proxy for past fires. [ABSTRACT FROM AUTHOR]

The consequences of land‐use change for savanna biodiversity remain undocumented in most regions of tropical Asia. One such region is western Maharashtra, India, where old‐growth savannas occupy a broad rainfall gradient and are increasingly rare due to agricultural conversion and afforestation.To understand the consequences of land‐use change, we sampled herbaceous plant communities of old‐growth savannas and three alternative land‐use types: tree plantations, tillage agriculture and agricultural fallows (n = 15 sites per type). Study sites spanned 457 to 1954 mm of mean annual precipitation—corresponding to the typical rainfall range of mesic savannas globally.Across the rainfall gradient, we found consistent declines in old‐growth savanna plant communities due to land‐use change. Local‐scale native species richness dropped from a mean of 12 species/m2 in old‐growth savannas to 8, 6 and 3 species/m2 in tree plantations, fallows and tillage agriculture, respectively. Cover of native plants declined from a mean of 49% in old‐growth savannas to 27% in both tree plantations and fallows, and 4% in tillage agriculture. Reduced native cover coincided with increased cover of invasive species in tree plantations (18%), fallows (18%) and tillage agriculture (3%).In analyses of community composition, tillage agriculture was most dissimilar to old‐growth savannas, while tree plantations and fallows showed intermediate dissimilarity. These compositional changes were driven partly by the loss of characteristic savanna species: 65 species recorded in old‐growth savannas were absent in other land uses. Indicator analysis revealed 21 old‐growth species, comprised mostly of native savanna specialists. Indicators of tree plantations (nine species) and fallows (13 species) were both invasive and native species, while the two indicators of tillage agriculture were invasive. As reflective of declines in savanna communities, mean native perennial graminoid cover of 27% in old‐growth savannas dropped to 9%, 7%, and 0.1% in tree plantations, fallows and tillage agriculture, respectively.Synthesis. Agricultural conversion and afforestation of old‐growth savannas in India destroys and degrades herbaceous plant communities that do not spontaneously recover on fallowed land. Efforts to conserve India's native biodiversity should encompass the country's widespread savanna biome and seek to limit conversion of irreplaceable old‐growth savannas. [ABSTRACT FROM AUTHOR]

The understanding of genetic diversity and evolutionary relationships within the genus Anadenanthera Speg. (Fabaceae) is limited. Brenan's classification recognized four species, but Altschul's classification currently recognizes only two species, each with two varieties. Both classifications were based solely on morphology. We analysed molecular data from 283 specimens using 12 SSRs and 186 specimens using ITS sequence data. The results showed that neither SSR-based genotyping nor ITS-based phylogeny supported Altschul's classification. Instead, they provided evidence of four reproductively isolated taxa and a single clade corresponding to one of Altschul's varieties. Additionally, ecological niche modelling (ENM) investigated the influence of past climate on the geographic distribution of Anadenanthera. The ENM results suggest that the 'varieties' may have occupied different regions of South America with distinct paleoclimates. On the basis of these findings, the authors suggest recognizing four species, as per Brenan's original classification. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Applied Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Despite growing recognition of the conservation values of grassy biomes, our understanding of how to maintain and restore biodiverse tropical grasslands (including savannas and open‐canopy grassy woodlands) remains limited. To incorporate grasslands into large‐scale restoration efforts, we synthesised existing ecological knowledge of tropical grassland resilience and approaches to plant community restoration. Tropical grassland plant communities are resilient to, and often dependent on, the endogenous disturbances with which they evolved – frequent fires and native megafaunal herbivory. In stark contrast, tropical grasslands are extremely vulnerable to human‐caused exogenous disturbances, particularly those that alter soils and destroy belowground biomass (e.g. tillage agriculture, surface mining); tropical grassland restoration after severe soil disturbances is expensive and rarely achieves management targets. Where grasslands have been degraded by altered disturbance regimes (e.g. fire exclusion), exotic plant invasions, or afforestation, restoration efforts can recreate vegetation structure (i.e. historical tree density and herbaceous ground cover), but species‐diverse plant communities, including endemic species, are slow to recover. Complicating plant‐community restoration efforts, many tropical grassland species, particularly those that invest in underground storage organs, are difficult to propagate and re‐establish. To guide restoration decisions, we draw on the old‐growth grassland concept, the novel ecosystem concept, and theory regarding tree cover along resource gradients in savannas to propose a conceptual framework that classifies tropical grasslands into three broad ecosystem states. These states are: (1) old‐growth grasslands (i.e. ancient, biodiverse grassy ecosystems), where management should focus on the maintenance of disturbance regimes; (2) hybrid grasslands, where restoration should emphasise a return towards the old‐growth state; and (3) novel ecosystems, where the magnitude of environmental change (i.e. a shift to an alternative ecosystem state) or the socioecological context preclude a return to historical conditions. [ABSTRACT FROM AUTHOR]

Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ancient tropical grassy biomes are often misrecognized as severely degraded forests. I trace this confusion to several factors, with roots in the nineteenth century, including misinterpretations of the nature of fire in savannahs, attempts to reconcile savannah ecology with Clementsian succession, use of physiognomic (structural) definitions of savannah and development of tropical degradation frameworks focused solely on forests. Towards clarity, I present two models that conceptualize the drivers of ecosystem degradation as operating in both savannahs and forests. These models highlight how human-induced environmental changes create ecosystems with superficially similar physiognomies but radically different conservation values. Given the limitation of physiognomy to differentiate savannahs from severely degraded forests, I present an alternative approach based on floristic composition. Data from eastern lowland Bolivia show that old-growth savannahs can be reliably distinguished by eight grass species and that species identity influences ecosystem flammability. I recommend that scientists incorporate savannahs in tropical degradation frameworks alongside forests, and that savannah be qualified as old-growth savannah in reference to ancient grassy biomes or derived savannah in reference to deforestation. These conceptual advances will require attention not only to tree cover, but also to savannah herbaceous plant species and their ecologies.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'., (© 2016 The Author(s).)