Localized effects of coarse woody material on soil oribatid communities diminish over 700 years of stand development in black-spruce-feathermoss forests

In the black-spruce clay-belt region of Western Québec, soil nutrients are limited due to paludification. Under paludified conditions, nutrient subsidies from decomposing surface coarse woody material (CWM) may be important particularly during the later stages of ecosystem development when deadwood from senescent trees has accumulated. For soil organisms, CWM can alter microclimatic conditions and resource availability. We compared abundance and species richness of oribatid mites below or adjacent to CWM across a chronosequence which spans ca. 700 years of stand development. We hypothesized that oribatid abundance and richness would be greater under the logs, particularly in later stages of forest development when logs may act as localized sources of carbon and nutrients in the paludified substrate. However, oribatid density was lower directly under CWM than adjacent to CWM but these differences were attenuated with time. We suggest that oribatids may be affected by soil compaction and also that such microarthropods are most likely feeding on recently fallen leaf litter, which may be rendered inaccessible by the presence of overlying CWM. This may also explain the progressive decline in oribatid density and diversity with time, which are presumably caused by decreases in litter availability due to self-thinning and Sphagnum growth. This is also supported by changes of different oribatid trophic groups, as litter feeders maintain different numbers relative to CWM with time while more generalist fungi feeders only show differences related to position in the beginning of the succession

Influence of Coarse Woody Material (CWM) on Soil Microarthropods in Black Spruce-Feather Moss Forests of Western Quebec

Increasing demands for biofuels have opened the possibility for an overall decrease in the amount of residual coarse woody material (CWM) in forests. While CWM is known to be an important resource for saproxylic species that reside within downed logs, the relative importance of CWM for organisms residing beneath, in the soil is poorly understood. In this context, CWM likely modifies conditions as well as nutrient levels for soil communities that lie beneath. The relative importance of CWM for underlying soil communities may be accentuated in the black-spruce clay-belt region of Western Québec where soil nutrients are extremely limited by paludification and extensive Sphagnum growth. To better understand the importance of CWM for soil microarthropods in this region, we sampled the soil microarthropods directly under CWM and 50 cm. apart, in 20 sites representing different states of development of a black spruce-feather moss forest type. While previous studies in other forest types showed little effect of woody material, our preliminary results suggest that Oribatid mites are influenced by CWM. However, contrary to our expectations, they have lower abundances and diversity in soil directly under logs than in open areas. We hypothesize that as nutrients in the forest floor are rendered inaccessible due to the thick Sphagnum layer of this forest, detritivore mites depend on recent leaf litter as nutrient resource. Conversely, logs in this case are likely to work as a cover to litter fall

Intercropping trees' effect on soil oribatid diversity in agro-ecosystems

The benefits of tree-based intercropping (TBI) compared to conventional agro-ecosystems in North America could include climate change mitigation and adaptation, although enhancing resilience to climate change through increasing soil diversity remains poorly explored. Diversity of soil microarthropods supports a series of ecological services that may be altered by soil desiccation due to climate change. Here we study the effect of red oak and hybrid poplar TBI on soil oribatid mite species assemblages associated to forage crops (mix of Timothy-grass and red clover). Abundance and species density of oribatids were affected by treatment, depth and the interaction of both variables. Abundance of oribatid mites was significantly lower in the oak TBI, showing a homogeneous vertical distribution in opposition to a decreasing with depth distribution under poplar TBI and conventional crops. Species density was significantly higher in the conventional crop, showing again significant differences in depth that were not present in both TBI treatments. Distance to tree did not affect mite abundance nor species density. TBI increased oribatid richness (obtained by sample-based rarefaction and extrapolation) only in the presence of oaks. The distribution of oribatids was strongly associated to tree fine root biomass and stress the importance of underground organic resources for the oribatid fauna and their ecological functions. If increasing drought associated with climate change desiccates superficial levels of agro-ecosystem soils, deeper sources of organic resources, such as tree roots, should become crucial in the maintenance of diverse microarthropod communities

Physical, Chemical, and Biological Indicators of Soil Quality in Mediterranean Vineyards under Contrasting Farming Schemes

The soil of most Spanish vineyards is strongly eroded and carbon depleted and is very poor in biodiversity. Growing evidence of the negative impacts of soil degradation on climate change mitigation, water quality, and plant production is pushing a shift from intensive viticulture to more sustainable management strategies of the vineyards. Among them, minimum impact and regenerative viticulture are gaining ground. However, field data are still necessary to assess the real effect of these new farming schemes on soil carbon stocks and soil functional biodiversity. We compared soil quality at three vineyards managed under intensive, regenerative, and minimum impact strategies using physical, chemical, and biological indicators. Soil carbon stocks were 2.3 and 3.4 times greater in the regenerative and the minimal impact vineyards than in the intensive vineyard, respectively. Soil biota was particularly favored by regenerative viticulture, with 26.2 times more protists, 3.1 times more nematodes, and 29.4 more microarthropods in the regenerative than in the intensive vineyard. Our results indicate that the ecological intensification of agricultural practices is highly promising to restore degraded agricultural soils under Mediterranean conditions. We also propose cost-effective soil bioindicators sensitive to agricultural management for their possible inclusion in soil monitoring programs

Soil carbon stocks and their variability across the forests, shrublands and grasslands of peninsular Spain

Accurate estimates of C stocks and fluxes of soil organic carbon (SOC) are needed to assess the impact of climate and land use change on soil C uptake and soil C emissions to the atmosphere. Here, we present an assessment of SOC stocks in forests, shrublands and grasslands of peninsular Spain based on field measurements in more than 900 soil profiles. SOC to a depth of 1 m was modelled as a function of vegetation cover, mean annual temperature, total annual precipitation, elevation and the interaction between temperature and elevation, while latitude and longitude were used to model the correlation structure of the errors. The resulting statistical model was used to estimate SOC in the ∼8 million pixels of the Spanish Forest Map (29.3 × 10⁶ ha). We present what we believe is the most reliable estimation of current SOC in forests, shrublands and grasslands of peninsular Spain thus far, based on the use of spatial modelling, the high number of profiles and the validity and refinement of the data layers employed. Mean concentration of SOC was 8.7 kg m-₂, ranging from 2.3 kg m-₂ in dry Mediterranean areas to 20.4 kg m-₂ in wetter northern locations. This value corresponds to a total stock of 2.544 Tg SOC, which is four times the amount of C estimated to be stored in the biomass of Spanish forests. Climate and vegetation cover were the main variables influencing SOC, with important ecological implications for peninsular Spanish ecosystems in the face of global change. The fact that SOC was positively related to annual precipitation and negatively related to mean annual temperature suggests that future climate change predictions of increased temperature and reduced precipitation may strongly reduce the potential of Spanish soils as C sinks. However, this may be mediated by changes in vegetation cover (e.g. by favouring the development of forests associated to higher SOC values) and exacerbated by perturbations such as fire. The estimations presented here provide a baseline to estimate future changes in soil C stocks and to assess their vulnerability to key global change drivers, and should inform future actions aimed at the conservation and management of C stocks

A Battery of soil and plant indicators of NBS environmental performance in the context of global change

Nature-based solutions (NBSs) for risk reduction produce environmental effects that must be assessed to evaluate their performance. In a context of climate change and growing concern about the loss of biodiversity, indicators informing about ecosystem complexity, resilience and stability are required. NBS projects hardly ever include environmental monitoring programs and, at best, NBS performance is evaluated based on elementary indicators that provide poor information about ecosystem functions and services. Within the framework of the PHUSICOS (EU, H2020) project, a NBS approach is being applied to reduce the hydrometeorological risks (rock falls and snow avalanches) that threaten a transnational road and a very populated town in the Pyrenees range. In both cases, the planned actions are modifying soil and vegetation structure and functioning as well as the environmental services they provide. Here we present a set of soil and plant indicators designed to be included in the postoperation monitoring plan of both NBS projects. We provide a description and information about the range of values of every indicator measured in the study sites together with indications about analytical methods and sampling calendar. We discuss the trade-offs between monetary cost, expertise requirements and meaningfulness of the indicators

A review of the combination among global change factors in forests, shrublands and pastures of the Mediterranean Region : beyond drought effects

Research in CRAG is also supported byCERCA institution (Generalitat de Catalunya).Climate change, alteration of atmospheric composition, land abandonment in some areas and land use intensification in others, wildfires and biological invasions threaten forests, shrublands and pastures all over the world. However, the impacts of the combinations between global change factors are not well understood despite its pressing importance. Here we posit that reviewing global change factors combination in an exemplary region can highlight the necessary aspects in order to better understand the challenges we face, warning about the consequences, and showing the challenges ahead of us. The forests, shrublands and pastures of the Mediterranean Basin are an ideal scenario for the study of these combinations due to its spatial and temporal heterogeneity, increasing and diverse human population and the historical legacy of land use transformations. The combination of multiple global change factors in the Basin shows different ecological effects. Some interactions alter the effects of a single factor, as drought enhances or decreases the effects of atmospheric components on plant ecophysiology. Several interactions generate new impacts: drought and land use changes, among others, alter water resources and lead to land degradation, vegetation regeneration decline, and expansion of forest diseases. Finally, different factors can occur alone or simultaneously leading to further increases in the risk of fires and biological invasions. The transitional nature of the Basin between temperate and arid climates involves a risk of irreversible ecosystem change towards more arid states. However, combinations between factors lead to unpredictable ecosystem alteration that goes beyond the particular consequences of drought. Complex global change scenarios should be studied in the Mediterranean and other regions of the world, including interregional studies. Here we show the inherent uncertainty of this complexity, which should be included in any management strategy

Reassessing global change research priorities in mediterranean terrestrial ecosystems : how far have we come and where do we go from here?

Aim: Mediterranean terrestrial ecosystems serve as reference laboratories for the investigation of global change because of their transitional climate, the high spatiotemporal variability of their environmental conditions, a rich and unique biodiversity and a wide range of socio-economic conditions. As scientific development and environmental pressures increase, it is increasingly necessary to evaluate recent progress and to challenge research priorities in the face of global change. - Location: Mediterranean terrestrial ecosystems. - Methods: This article revisits the research priorities proposed in a 1998 assessment. - Results: A new set of research priorities is proposed: (1) to establish the role of the landscape mosaic on fire-spread; (2) to further research the combined effect of different drivers on pest expansion; (3) to address the interaction between drivers of global change and recent forest management practices; (4) to obtain more realistic information on the impacts of global change and ecosystem services; (5) to assess forest mortality events associated with climatic extremes; (6) to focus global change research on identifying and managing vulnerable areas; (7) to use the functional traits concept to study resilience after disturbance; (8) to study the relationship between genotypic and phenotypic diversity as a source of forest resilience; (9) to understand the balance between C storage and water resources; (10) to analyse the interplay between landscape-scale processes and biodiversity conservation; (11) to refine models by including interactions between drivers and socio-economic contexts; (12) to understand forest-atmosphere feedbacks; (13) to represent key mechanisms linking plant hydraulics with landscape hydrology. - Main conclusions:(1) The interactive nature of different global change drivers remains poorly understood. (2) There is a critical need for the rapid development of regional- and global-scale models that are more tightly connected with large-scale experiments, data networks and management practice. (3) More attention should be directed to drought-related forest decline and the current relevance of historical land use