Sclerophyllous Research Articles

Selecting Low-Flammability Plants as Green Firebreaks within Sustainable Urban Garden Design

In response to an increasing risk of property loss from wildfires at the urban–wildland interface[…]

Wildfire in wet sclerophyll forests: the interplay between disturbances and fuel dynamics

AbstractThere are multiple pathways for vegetation to change following disturbances. Understanding those post‐disturbance pathways is critical for managing wildfire risk since vegetation is fuel in a wildfire context. Across forest systems, there is considerable debate about disturbance‐related changes to fuels and flammability. This study investigated post‐disturbance fuel trajectories following three disturbance types—high severity wildfire, low severity wildfire, and clear‐fell logging. Fuels were measured in a chrono‐sequence of 141 sites in Mountain Ash (Eucalyptus regnans)‐dominated wet sclerophyll forest in southeastern Australia, a particularly contentious forest system. Wildfires are an important part of the lifecycle of these forests, but too frequent fire can threaten post‐fire regeneration. Large wildfires (in 2009, 1983 and 1939) and ongoing public and scientific debate over clear‐fell logging highlight the need to better understand post‐disturbance trajectories for fuel and flammability in wet sclerophyll forests. We used empirical data to test 10, sometimes contradictory, hypotheses from the scientific literature regarding post‐disturbance pathways for fuel following wildfire and logging. Only five hypotheses were supported with surface fine fuels, fuel hazard, species composition, and vertical structure driving overall differences in post‐disturbance fuel trajectories. The implications for flammability remain uncertain because the independent and interactive effects of many fuel components on overall flammability remain unquantified. Importantly, we found there were always high quantities of fuel, irrespective of disturbance history, which demonstrates that fire occurrence is not fuel‐limited in wet sclerophyll forests. Under conditions of abundant fuel, fuel moisture could become critical to fire occurrence. Therefore, forest management should prioritize efforts to quantify not only the importance of individual fuel components to flammability but also fuel moisture dynamics in wet sclerophyll forests. As the climate (and fuels) becomes drier under climate change, it will be a major challenge to manage fire regimes in these highly valued forests.

Logging and fire regimes alter plant communities.

Disturbances are key drivers of plant community composition, structure, and function. Plant functional traits, including life forms and reproductive strategies are critical to the resilience and resistance of plant communities in the event of disturbance. Climate change and increasing anthropogenic disturbance are altering natural disturbance regimes globally. When these regimes shift beyond the adaptive resilience of plant functional traits, local populations and ecosystem functions can become compromised. We tested the influence of multiple disturbances, of varying intensity and frequency, on the composition and abundance of vascular plant communities and their respective functional traits (life forms and reproductive strategies) in the wet sclerophyll, Mountain Ash Eucalyptus regnans forests of southeastern Australia. Specifically, we quantified the effect of the type and number of disturbances (including fires, clearcut logging, and salvage logging) on plant community composition. We found that clearcut and salvage logging and the number of fires significantly influenced plant community composition and functional traits. Specifically, multiple fires resulted in lower populations of species that depend on on-site seeding for persistence. This includes the common tree species Eucalyptus regnans, Pomaderris aspera, and Acacia dealbata. In contrast, clearcut and salvage logged sites supported abundant on-site seeder species. However, species that depend on resprouting by surviving individuals, such as common and keystone "tree ferns" Dicksonia antarctica and Cyathea australis, declined significantly. Our data have important implications for understanding the relationship between altered disturbance regimes and plant communities and the respective effects on ecosystem function. In a period of rapid global environmental change, with disturbances predicted to increase and intensify, it is critical to address the impact of altered disturbance regimes on biodiversity.

Assessment of ecosystem functioning from space: Advancements in the Habitats Directive implementation

The Habitats Directive (HD) and the Natura 2000 network establish a common framework for maintaining European natural habitats in a favourable conservation status and represent the main instrument used by conservation decision makers in the European Union. Habitat conservation status depends on the sum of the influences acting upon the habitat and its typical species that may affect its long-term natural distribution, structure and functions. Thus, ecosystem functioning is influenced by the diversity, number and functional traits of the species occurring in a habitat. Although the HD establishes that representative species should be selected to reflect favourable structure and functioning of the habitat type, it would not be realistic to associate species with all aspects of structure and functioning given the variability of Annex I habitats. This constraint led us to seek new approaches that allow a more direct assessment of the ecosystem functioning for natural habitats in space and time. We propose a remote sensing-based approach to characterize and assess the ecosystem functioning of habitats. As a case study, we applied our approach to three Mediterranean natural habitat types from the Iberian Peninsula included in Annex I of the Habitats Directive, i.e., Mediterranean sclerophyllous forest, Mediterranean deciduous forest and Sub-Mediterranean and temperate scrub. First, we estimated two key descriptors of ecosystem functioning derived from the Enhanced Vegetation Index and related them to primary production dynamics by using satellite images captured by the MODIS sensor for each year between 2001 and 2012. Second, we arranged these functional descriptors in two-dimensional space and calculated the distances from the habitats assessed to the reference sites, i.e., habitat patches that showed an optimal conservation status of composition and structure. Then, the distances were averaged over the period, and the habitats were categorized according to their mean distances as favourable or unfavourable-inadequate or unfavourable-bad, as outlined in the reporting guidelines under Article 17 of the Directive. Our approach provides new procedures to assess ecosystem functions across space and time, while complying with reporting obligations derived from the HD.

Using Landsat Spectral Indices in Time-Series to Assess Wildfire Disturbance and Recovery

Satellite earth observation is being increasingly used to monitor forests across the world. Freely available Landsat data stretching back four decades, coupled with advances in computer processing capabilities, has enabled new time-series techniques for analyzing forest change. Typically, these methods track individual pixel values over time, through the use of various spectral indices. This study examines the utility of eight spectral indices for characterizing fire disturbance and recovery in sclerophyll forests, in order to determine their relative merits in the context of Landsat time-series. Although existing research into Landsat indices is comprehensive, this study presents a new approach, by comparing the distributions of pre and post-fire pixels using Glass’s delta, for evaluating indices without the need of detailed field information. Our results show that in the sclerophyll forests of southeast Australia, common indices, such as the Normalized Difference Vegetation Index (NDVI) and the Normalized Burn Ratio (NBR), both accurately capture wildfire disturbance in a pixel-based time-series approach, especially if images from soon after the disturbance are available. However, for tracking forest regrowth and recovery, indices, such as NDVI, which typically capture chlorophyll concentration or canopy ‘greenness’, are not as reliable, with values returning to pre-fire levels in 3–5 years. In comparison, indices that are more sensitive to forest moisture and structure, such as NBR, indicate much longer (8–10 years) recovery timeframes. This finding is consistent with studies that were conducted in other forest types. We also demonstrate that additional information regarding forest condition, particularly in relation to recovery, can be extracted from less well known indices, such as NBR2, as well as textural indices incorporating spatial variance. With Landsat time-series gaining in popularity in recent years, it is critical to understand the advantages and limitations of the various indices that these methods rely on.

The threatened status of the hollow dependent arboreal marsupial, the Greater Glider ( Petauroides volans ), can be explained by impacts from wildfire and selective logging

Abstract Logging and fires represent the major disturbance regimes in Eucalyptus forests and these can have varying effects on populations of forest fauna depending on their intensity and/ or frequency. Knowledge of the effects of fires on arboreal marsupials is limited and to the best of our knowledge no previous research has considered the effect of fire frequency on populations of these species. The aim of this study was to examine the effects of fire frequency (canopy-consuming wildfires) and logging intensity on the Greater Glider, Petauroides volans, a species of hollow dependent gliding possum that has recently been listed as vulnerable to extinction under Australian biodiversity law. Surveys were completed across a selective logging intensity and fire frequency gradient in tall wet (WSF) and tall dry sclerophyll forests (DSF) in north-eastern New South Wales, Australia. Generally, P. volans was restricted to WSF, where even a single fire, 10 years prior, significantly reduced the density of P. volans in comparison to unburnt areas. Significant negative impacts from intensive logging were also detected. These effects may explain observed declines in the abundance of P. volans over much of its range as well as its scarcity in the more fire prone DSF. To counteract these effects, we recommend not implementing prescribed fire under high or greater fire weather danger conditions near high-density populations of this species, along with increased retention of hollow-bearing trees during timber harvesting and/ or wider riparian buffers in areas where high density populations of P. volans occur.

Predicting community rank‐abundance distributions under current and future climates

Understanding influences of environmental change on biodiversity requires consideration of more than just species richness. Here we present a novel framework for understanding possible changes in species' abundance structures within communities under climate change. We demonstrate this using comprehensive survey and environmental data from 1748 woody plant communities across southeast Queensland, Australia, to model rank‐abundance distributions (RADs) under current and future climates. Under current conditions, the models predicted RADs consistent with the region's dominant vegetation types. We demonstrate that under a business as usual climate scenario, total abundance and richness may decline in subtropical rainforest and shrubby heath, and increase in dry sclerophyll forests. Despite these opposing trends, we predicted evenness in the distribution of abundances between species to increase in all vegetation types. By assessing the information rich, multidimensional RAD, we show that climate‐driven changes to community abundance structures will likely vary depending on the current composition and environmental context.

What was the vegetation in northwest Australia during the Paleogene, 66–23million years ago?

Fossil pollen and spores preserved in drillcore from both the upper South Alligator River (SARV) in the Kakadu National Park, Northern Territory and the North-West Shelf, Western Australia provide the first record of plants and plant communities occupying the coast and adjacent hinterland in north-west Australia during the Paleogene 66 to 23million years ago. The palynologically-dominant woody taxon is Casuarinaceae, a family now comprising four genera of evergreen scleromorphic shrubs and trees native to Australia, New Guinea, South-east Asia and Pacific Islands. Rare taxa include genera now mostly restricted to temperate rainforest in New Guinea, New Caledonia, New Zealand, South-East Asia and/or Tasmania, e.g. Dacrydium, Phyllocladus and the Nothofagus subgenera Brassospora and Fuscospora. These appear to have existed in moist gorges on the Arnhem Land Plateau, Kakadu National Park. No evidence for Laurasian rainforest elements was found. The few taxa that have modern tropical affinities occur in Eocene or older sediments in Australia, e.g. Lygodium, Anacolosa, Elaeagnus, Malpighiaceae and Strasburgeriaceae. We conclude the wind-pollinated Oligocene to possibly Early Miocene vegetation in the upper SARV was Casuarinaceae sclerophyll forest or woodland growing under seasonally dry conditions and related to modern Allocasuarina/Casuarina formations. There are, however, strong floristic links to coastal communities growing under warm to hot, and seasonally to uniformly wet climates in north-west Australia during the Paleocene-Eocene.

Coupling of microbial nitrogen transformations and climate in sclerophyll forest soils from the Mediterranean Region of central Chile

The Mediterranean region of central Chile is experiencing extensive “mega-droughts” with detrimental effects for the environment and economy of the region. In the northern hemisphere, nitrogen (N) limitation of Mediterranean ecosystems has been explained by the decoupling between N inputs and plant uptake during the dormant season. In central Chile, soils have often been considered N-rich in comparison to other Mediterranean ecosystems of the world, yet the impacts of expected intensification of seasonal drought remain unknown. In this work, we seek to disentangle patterns of microbial N transformations and their seasonal coupling with climate in the Chilean sclerophyll forest-type. We aim to assess how water limitation affects microbial N transformations, thus addressing the impact of ongoing regional climate trends on soil N status. We studied four stands of the sclerophyll forest-type in Chile. Field measurements in surface soils showed a 67% decline of free-living diazotrophic activity (DA) and 59% decrease of net N mineralization rates during the summer rainless and dormant season, accompanied by a stimulation of in-situ denitrification rates to values 70% higher than in wetter winter. Higher rates of both free-living DA and net N mineralization found during spring, provided evidence for strong coupling of these two processes during the growing season. Overall, the experimental addition of water in the field to litter samples almost doubled DA but had no effect on denitrification rates. We conclude that coupling of microbial mediated soil N transformations during the wetter growing season explains the N enrichment of sclerophyll forest soils. Expected increases in the length and intensity of the dry period, according to climate change models, reflected in the current mega-droughts may drastically reduce biological N fixation and net N mineralization, increasing at the same time denitrification rates, thereby potentially reducing long-term soil N capital.

Effects of fire regime on plant species richness and composition differ among forest, woodland and heath vegetation

AbstractQuestionDo the effects of fire regimes on plant species richness and composition differ among floristically similar vegetation types?LocationBooderee National Park, south‐eastern Australia.MethodsWe completed floristic surveys of 87 sites in Sydney Coastal dry sclerophyll vegetation, where fire history records have been maintained for over 55 years. We tested for associations between different aspects of the recent fire history and plant species richness and composition, and whether these relationships were consistent among structurally defined forest, woodland and heath vegetation types.ResultsThe relationship between fire regime variables and plant species richness and composition differed among vegetation types, despite the three vegetation types having similar species pools. Fire frequency was positively related to species richness in woodland, negatively related to species richness in heath, and unrelated to species richness in forest. These different relationships were explained by differences in the associations between fire history and species traits among vegetation types. The negative relationship between fire frequency and species richness in heath vegetation was underpinned by reduced occurrence of resprouting species at high fire frequency sites (more than four fires in 55 years). However, in forest and woodland vegetation, resprouting species were not negatively associated with fire frequency.ConclusionsWe hypothesize that differing relationships among vegetation types were underpinned by differences in fire behaviour, and/or biotic and abiotic conditions, leading to differences in plant species mortality and post‐fire recovery among vegetation types. Our findings suggest that even when there is a high proportion of shared species between vegetation types, fires can have very different effects on vegetation communities, depending on the structural vegetation type. Both research and management of fire regimes may therefore benefit from considering vegetation types as separate management units.

Impact of Austropuccinia psidii (myrtle rust) on Myrtaceae-rich wet sclerophyll forests in south east Queensland.

In April 2010, Austropuccinia psidii (formerly Puccinia psidii) was detected for the first time in Australia on the central coast of New South Wales. The fungus spread rapidly along the east coast and can now be found infecting vegetation in a range of native forest ecosystems with disease impacts ranging from minor leaf spots to severe shoot and stem blight and tree dieback. Localised extinction of some plant species has been recorded. In 2014, the impact of A. psidii was observed for the first time in a wet sclerophyll site with a rainforest understory, dominated by species of Myrtaceae, in Tallebudgera Valley, south east Queensland, Australia. This study aimed to determine the impact of A. psidii on individual species and species composition. Here we provide quantitative and qualitative evidence on the significant impact A. psidii has in native ecosystems, on a broader range of species than previously reported. Archirhodomyrtus beckleri, Decaspermum humile, Gossia hillii and Rhodamnia maideniana are in serious decline, with significant increases in tree mortality over the period of our study. This research further highlights the potential of this invasive pathogen to negatively impact native ecosystems and biodiversity.

Restoring connectivity between fragmented woodlands in Chile with a reintroduced mobile link species

We examine the feasibility of improving connectivity between of two dryland woodland types (“espinal”, a savanna type habitat, and sclerophyllous forest) in the Mediterranean climate zone of Chile, for restoration purposes. The restoration approach we examine involves the reintroduction of guanacos (Lama guanicoe) in a “transhumant rewilding” model. The guanacos stimulate the growth of Acacia caven in espinal through browsing, and also provide seed and nutrient dispersal and connectivity between the two woodland types. As in many drylands, degradation is problematic in this region, but clear criteria or maps of degradation are lacking. Thus to assess where restoration is required, how degradation has varied with ENSO across years, and how degraded areas are distributed across the region, we construct an index of woodland condition from Normalized Difference Vegetation Index (NDVI), Net Primary Production (NPP) and evapotranspiration (ET), derived from MODIS data at 1km resolution for each year between 2000 and 2013 inclusive. We construct a least-cost path for each year, which models the possible transhumant movements of herded guanacos between low and high quality woodlands each year. We find highly fragmented areas of espinal, sclerophyllous forest, and overlap between these, which we identified as sucessional habitat. We also found a fully-connected network linking low-quality and high-quality fragments of all types of woodland in each year. This shows that guanaco transhumant herding has the capacity to be used to create regional connectivity and restoration services.

Phytosociology and ecology of the Mediterranean forests ecosystems in the Amalfi Coast (Monti Lattari, Italy)

The forest vegetation of the southern sector of the Monti Lattari complex (Amalfi Coast) has been investigated due to the lack of information on vegetation within an area of worldwide relevance and with a high floristic richness. This area shows several environmental peculiarities due to the marked orography, with pedologic features varying from carbonate to volcanic character, and bioclimatic conditions varying in a relatively short space from Mediterranean to temperate types. The study involved an extensive phytosociological survey and the analyses revealed clear differences among the forest communities, whose syntaxonomical queries and the biogeographic and ecological characters have been discussed. The communities varied from the coastal sclerophyllous forests (Cyclamino repandi–Quercetum ilicis) to the mixed thermophilous deciduous forests (Festuco exaltatae–Aceretum neapolitani, Seslerio autumnalis–Aceretum obtusati), and from the mountain neutral–subacid forests (Salvio glutinosae–Alnetum cordatae, Castanea sativa groupment, Asperulo taurinae–Alnetum cordatae) to the mountain beech forest (Anemono apenninae–Fagetum sylvaticae). Multivariate analysis showed the high relevance of steepness, elevation and pyroclastic presence, and a low relevance of aspect in the discrimination of forest communities. Syntaxonomical interpretations showed the affinity of the local communities with those of the southern Italy, but also some interesting peculiarity. Data highlight the area as a geographical boundary and phytogeographic hinge between central and southern Italy.

Evolution in Australia’s mesic biome under past and future climates: Insights from a phylogenetic study of the Australian Rock Orchids (Dendrobium speciosum complex, Orchidaceae)

The Australian mesic biome spans c. 33° of latitude along Australia’s east coast and ranges and is dissected by historical and contemporary biogeographical barriers. To investigate the impact of these barriers on evolutionary diversification and to predict the impact of future climate change on the distribution of species and genetic diversity within this biome, we inferred phylogenetic relationships within the Dendrobium speciosum complex (Orchidaceae) across its distribution and undertook environmental niche modelling (ENM) under past, contemporary and projected future climates.Neighbor Joining tree inference, NeighborNet and Structure analyses of Amplified Fragment Length Polymorphism (AFLP) profiles for D. speciosum sampled from across its distribution showed that the complex consists of two highly supported main groups that are geographically separated by the St. Lawrence gap, an area of dry sclerophyll forest and woodland. The presence of several highly admixed individuals identified by the Structure analysis provided evidence of genetic exchange between the two groups across this gap. Whereas previous treatments have recognised between one to eleven species, the molecular results support the taxonomic treatment of the complex as a single species with two subspecies.The ENM analysis supported the hypothesis that lineage divergence within the complex was driven by past climatic changes. The St. Lawrence gap represented a stronger biogeographic barrier for the D. speciosum complex during the cool and dry glacial climatic conditions of the Pleistocene than under today’s interglacial conditions. Shallow genetic divergence was found within the two lineages, which mainly corresponded to three other biogeographic barriers: the Black Mountain Corridor, Glass House Mountains and the Hunter Valley. Our ENM analyses provide further support for the hypothesis that biogeographic barriers along Australia’s east coast were somewhat permeable to genetic exchange due to past episodic range expansions and contractions caused by climatic change resulting in recurrent contact between previously isolated populations. An overall southward shift in the distribution of the complex under future climate scenarios was predicted, with the strongest effects on the northern lineage. This study contributes to our understanding of the factors shaping biodiversity patterns in Australia’s mesic biome.

A global analysis of plant recovery performance from water stress

Plant post‐drought recovery performance is essential to predict shifts in ecosystem dynamics and production during frequent climate change‐driven drought events. Yet, it is not clear how post‐drought recovery is related to evolutionary and geographic variations in plants. In this study, we generated a global data set of post‐drought recovery performance in 140 plant species from published studies. We quantified the plant post‐drought recovery performance by calculating a recovery index for multiple plant physiological and hydraulic parameters, including leaf water potential, net photosynthetic rate, leaf hydraulic conductance and shoot biomass. The magnitude of recovery among four plant functional types (deciduous angiosperms, evergreen angiosperms, gymnosperms, and crops), two plant growth forms (shrubs and trees), two water management strategies (isohydric and anisohydric), four xylem porosity types (diffuse, ring, semi‐ring and tracheid), and four major biomes (dry sclerophyll forest, boreal forest, temperate forest and tropical/subtropical forest) were compared. We found the inability to completely recover immediately after severe water stress is ubiquitous across all plant functional types and growth forms, while the rate and magnitude of post‐drought recovery varied greatly across different plant taxonomic categories and geographic ranges. In general, plant hydraulic architecture, leaf anatomy and physiology affect plants’ propensity towards recovery, and reflect evolutionary consequences of plant adaptation to their habitat. Due to the essential role of plant functional traits in regulating carbon storage in each biome, a better understanding plant post‐drought recovery performance could improve our predictions on ecosystem productivity in a rapidly changing climate.

Last Glacial Maximum and Last Glacial–Interglacial Transition pollen record from northern NSW, Australia: evidence for a humid late Last Glacial Maximum and dry deglaciation in parts of eastern Australia

ABSTRACTThis paper presents the results of a palynological investigation into the late Last Glacial Maximum (LGM) and last deglaciation (ca. 20 000–9000 cal a BP) from Little Llangothlin Lagoon, in the sub‐tropics of eastern Australia. The Lagoon held permanent water during the late LGM and early deglaciation but was intermittently dry during the late deglaciation. During the late LGM, local vegetation was dominated by a sub‐alpine herbfield but the significant presence of rainforest taxa in the pollen record indicates the survival of rainforest, rainforest margin or wet sclerophyll communities close to the site. By ca. 17 000 cal a BP, open Eucalyptus forest replaced the alpine herbfield vegetation indicating that warming had commenced. Rainforest taxa disappeared at this time but re‐appeared at the end of the deglaciation. The LGM conditions are consistent with a dominant circulation system whereby persistent high pressure over eastern Australia brings onshore easterlies to this region and maintains humid conditions along the east coast and highlands of the Great Dividing Range. This is similar to modern winter circulation but the persistence of rainforest and wet sclerophyll taxa suggests an increase in easterly flow over modern conditions during the LGM. Copyright © 2017 John Wiley & Sons, Ltd.

Does the removal of Lantana camara influence eucalypt canopy health, soil nutrients and site occupancy of a despotic species?

Weed removal experiments provide strong evidence for weed impacts, validating management techniques and demonstrating the means by which biodiversity can be maintained. We examined the effects of removing Lantana (Lantana camara) through herbicide application in eucalypt-dominated sclerophyll forest and, then measured the response of soil carbon and nitrogen levels, tree canopy health and the density of Bell Miners (Manorina melanophrys) a bird species thought to amplify the negative impacts of Lantana on tree health. Four sites in northern New South Wales were monitored for 2.5years. We measured Lantana health, (index of height, number of stems and leaves present), soil nutrients (nitrogen and carbon at two depths: 0–10cm and 20–30cm), Bell Miner density (using acoustic methods) and eucalypt canopy health (5 trees/quadrat) in six 50×50m quadrats per site (n=24; 12 treated, 12 untreated). Lantana foliage in treated quadrats was sprayed with glyphosate. Lantana showed significant reductions in health within 6months of treatment and remained in a debilitated state compared to control quadrats for the duration of the project. Despite this, soil nutrients, Bell Miner density and canopy health did not differ between intact and treated quadrats for up to 2years after treatment. The lack of impact on soil nutrient level or tree canopy health despite large changes in Lantana abundance in treatment sites was unexpected, and may indicate that Lantana is unimportant in shaping these measures. However, a more likely explanation is that longer term monitoring is required before the full impact of Lantana removal can be detected. The level of habitat modification following herbicide application was insufficient to stimulate relocation of Bell Miner colonies. Further investigation is required into how Lantana removal affects Bell Miner density, soil nutrient levels and canopy health in the medium to long term.

Aridity indices predict organic matter decomposition and comminution processes at landscape scale

Microbial decomposition and invertebrate comminution of a particular organic substrate are largely regulated by temperature and water availability. Numerous metrics have been used to model decay processes at large regional-to-global scales. However, their use at smaller landscape scales might not be practical or feasible. Aridity, generally defined as the balance between long term annual precipitation (P) and potential evapotranspiration (PET), is a metric that synthesizes the major climatic drivers regulating ecosystem processes including the activity of microbes and invertebrates on the forest floor. Thus, aridity indices (AIs) can theoretically represent suitable predictors of decomposition and comminution processes at landscape scale.We investigated our hypothesis in a sclerophyll forest in south-east Australia, where decomposition and comminution rates of Eucalyptus globulus leaf litter were measured in eight sites positioned along an aridity gradient caused by variable exposure to solar radiation. Four sites were also instrumented to continuously monitor air, litter and soil microclimatic variables.We found that AIs were strongly related to above- and below-ground microbial decomposition rates, as well as above-ground comminution rates. Some microclimatic variables, such as shortwave radiation, air relative humidity and litter temperature were also significantly related to above-ground processes, but not below-ground decomposition. Among the AIs tested, the index calculated using the Priestley-Taylor equation for PET had consistently higher coefficients of determination with decomposition and comminution rates. Our case study suggests that AIs can represent robust predictors of both decomposition and comminution processes at landscape scale and useful surrogates for more expensive microclimatic predictors collected at site level. AIs could also be used across spatial scales (from local to continental) to improve biogeochemical and hydrological models by incorporating a spatially-explicit representation of decay processes.

The old charcoal kiln sites in Central Italian forest landscapes

Production of wood charcoal in the Mediterranean countries started over two millennia ago and vanished almost completely only in the last century. The legacy of this activity are thousands of abandoned charcoal kiln platforms, in which soil and vegetation characteristics are deeply affected. Understanding the consequences of such effects at the forest level demands a better knowledge of the density, distribution and morphology of these sites, as well as the influence of forest type and local geomorphological characteristics. We examined these aspects using field surveys and Airborne Laser Scanning (ALS) data in 1-ha sample quadrats distributed along an altitudinal gradient in three major forest types of Central Italy, namely evergreen sclerophyllous forest, oak-dominated thermophilous deciduous forest and montane beech forest. We found on average 5.5 kiln sites per ha. The highest overall surface proportion covered by charcoal platforms was recorded in oak-dominated forests, due to their generally larger size. In beech forests, kiln platforms were more numerous than in the other two forest types, but smaller. Density was intermediate in the sclerophyllous forests, where the overall proportion of surface was lowest. The charcoal-enriched soil layer was usually single and continuous (e.g. not interrupted by mineral layers). The thickness of this layer was similar in the three forest types, but increased with slope inclination. Several features of our kiln platforms such as density and shape were distinct from others in Central and Northern Europe, probably reflecting different forest histories and purposes for which they were built. Using ALS, we could detect all kiln platforms in beech forest on steep slopes and approximately 75% of the kilns in oak forests on hilly terrain. Hence, all further ecologically- or archaeologically-oriented study in our region at the landscape level will benefit from the use of hillshade and/or slope images from ALS data.

Former charcoal platforms in Mediterranean forest areas: a hostile microhabitat for the recolonization by woody species

Production of wood charcoal is a traditional form of forest use that lasted for millennia in the Mediterranean countries. Following their almost complete abandonment in the last century, thousands of old charcoal platforms remain in present-day forest landscapes. These sites are characterized by peculiar ecological conditions, whose effects on the recolonization by woody plants are still unknown. We examined 61 platforms in evergreen sclerophyllous woodlands and deciduous broadleaf forests with oaks and beech, spread over a wide geographic range in Tuscany (Italy). At each site, one kiln plot (on charcoal platform) and one control plot (in the adjacent stand) were established, and soil, light conditions and herb cover were measured. We examined species richness and composition of trees and shrubs in the understorey layer (<1.3 m) and in the “established regeneration” layer (> 1.3-4 m). In the latter, structural parameters such as number of stools, dbh, mean height and number of stems were compared. The density of seedlings of dominant tree species in the understorey was also measured in a subsample of sites per forest type. In the understorey, a general positive effect of kiln platforms was found on species richness at both the habitat and plot-scale level, as well as on species composition, especially in oak forests. Increased light availability, total C content and soil pH were positively related with species richness, while N content was a negative predictor. Density of seedlings was not substantially affected. Contrastingly, woody species richness in the established regeneration layer was considerably lower in the kiln plots of all three forest types. In sclerophyllous forests, all species in this layer were taller, denser and with a higher basal area compared to control plots, while regeneration was completely lacking on platforms of the two other forest types. Soil N content had a positive influence on structural parameters, while total C content resulting from charcoal accumulation had a negative influence. We conclude that charcoal platforms are a favorable microhabitat only in the first regeneration stages of woody species, as their further growth is hindered by long-term effects that should be investigated with an experimental approach.