Distribution of the nurse species Pycnophyllum molle J. Rémy and P. weberbaueri Muschl. in the Andean dry puna (Arequipa district-Southern Peru): role of topographic/soil variability and disturbance regime

The dry Puna is the widest pastoral ecosystem of the tropical alpine Andes, characterized by harsh environmental conditions (long and intense drought stress periods and un-fertile soils) and grazed by wild and domestic camelids. In these conditions, facilitation is of key importance in plant diversity conservation. Indeed, facilitation is a positive plant-plant interaction by which the so called nurse species provide environmental amelioration of harsh conditions and/or refuge to other plants (beneficiary species), which otherwise might fail to establish. The research aims were to understand which ecological variables affect the distribution of the potential nurse cushion species Pycnophyllum molle J. Remy and P. weberbaueri Muschl., and if these species are affected by grazing disturbance. The study area (4000-4900 m a.s.l.) is located in the southern Peruvian Andes. Data of species cover, topographic and soil features, besides type of disturbance were collected along transects. We used canonical redundancy analysis to understand the relations between the cover of the two Pycnophyllum species and the above mentioned constraining variables. Results indicate that both the Pycnophyllum species grow on sandy loam, moderately acid soils, with low organic matter and very poor nitrogen content, and avoid high disturbance intensities. molle is more sensitive than P weberbaueri to disturbance, and grows on relatively more fertile soils, also at higher altitudes and on steeper slopes characterized by greater rockiness

Evidence of Facilitation Cascade Processes as Drivers of Successional Patterns of Ecosystem Engineers at the Upper Altitudinal Limit of the Dry Puna

Facilitation processes constitute basic elements of vegetation dynamics in harsh systems. Recent studies in tropical alpine environments demonstrated how pioneer plant species defined as "ecosystem engineers" are capable of enhancing landscape-level richness by adding new species to the community through the modification of microhabitats, and also provided hints about the alternation of different ecosystem engineers over time. Nevertheless, most of the existing works analysed different ecosystem engineers separately, without considering the interaction of different ecosystem engineers. Focusing on the altitudinal limit of Peruvian Dry Puna vegetation, we hypothesized that positive interactions structure plant communities by facilitation cascades involving different ecosystem engineers, determining the evolution of the microhabitat patches in terms of abiotic resources and beneficiary species hosted. To analyze successional mechanisms, we used a "space-for-time" substitution to account for changes over time, and analyzed data on soil texture, composition, and temperature, facilitated species and their interaction with nurse species, and surface area of engineered patches by means of chemical analyses, indicator species analysis, and rarefaction curves. A successional process, resulting from the dynamic interaction of different ecosystem engineers, which determined a progressive amelioration of soil conditions (e.g. nitrogen and organic matter content, and temperature), was the main driver of species assemblage at the community scale, enhancing species richness. Cushion plants act as pioneers, by starting the successional processes that continue with shrubs and tussocks. Tussock grasses have sometimes been found to be capable of creating microhabitat patches independently. The dynamics of species assemblage seem to follow the nested assemblage mechanism, in which the first foundation species to colonize a habitat provides a novel substrate for colonization by other foundation species through a facilitation cascade process

Short communication: Effects of summer rainfall variations on sheep body state and farming sustainability in sub-Mediterranean pastoral systems

In sub-Mediterranean climate the grassland aboveground phytomass production peaks in late spring and drops in summer, when the decrease of the pasture feed value may lead to the worsening of the animal welfare. Our goal was to define the summer rainfall values leading to a decrease of semi-extensive farming system sustainability in sub-Mediterranean regions. Summer rainfall variations reflect in the aboveground phytomass production and on the sheep body state. Differences of body condition score (BCS) among years were significant in late summer, which is the mating period for sheep. In the driest year the BCS of end August drops down to 2.1, largely below the value considered sufficient to ensure the animal breeding/milking performances (2.5). Reduction of summer rainfall greater than 15–20% compared to the normal average value (thus less than expected by the scenario of climate change) might be detrimental for semi-extensive rearing sustainability in sub-Mediterranean climate

Filtering effect of temporal niche fluctuation and amplitude of environmental variations on the trait-related flowering patterns: lesson from sub-Mediterranean grasslands

Timing of flowering is a critical component of community assembly, but how plant traits respond to heterogeneity of resources has been identified mostly through observations of spatial variations. Thus, we performed a trait-based phenological study in sub-Mediterranean grasslands to assess the importance of temporal variation of resources in the species assemblage processes. We found that early flowering species have traits allowing for slow resource acquisition and storage but rapid growth rate. Instead, mid- and late-flowering species exhibited sets of strategies devoted to minimizing water loss by evapotranspiration or aimed at maximizing the species’ competitive ability, thanks to slow growth rate and more efficient resource acquisition, conservation and use. Our findings were consistent with the fluctuation niche theory. We observed that the amplitude of the environmental fluctuations influences the type and number of strategies positively filtered by the system. In fact, in the most productive grasslands, we observed the highest number of indicator trait states reflecting strategies devoted to the storage of resources and competition for light. Results seem also indicate that temporal variation of resources plays a role in trait differentiation and richness within a plant community, filtering traits composition of grasslands in the same direction, as formerly proved for spatial heterogeneity of resources

Land use change in the high mountain belts of the central Apennines led to marked changes of the grassland mosaic

Aims High mountain pastures are hotspots of biodiversity, but grazing cessation and climate change are causing tall-grass encroachment and expansion of scrublands and forests. As part of biodiversity conservation efforts, grassland variation needs to be investigated at different spatial scales. We aimed to assess the landscape mosaic variation that occurred between 1988 and 2015 in the higher Mediterranean mountains. We investigated the recovery or land-degradation processes related to land use change, the effects of site condition, the impacts on grassland mosaic heterogeneity, and the threats to biodiversity. Location Sibillini Mountains (central Italy), over 1,650 m a.s.l. Methods We used two-step object-based supervised classification on Landsat 5 and 8 satellite images to analyze changes in landscape patterns and vegetation cover on formerly low-intensity pastures, by assessing the Normalized Difference Vegetation Index variation between 1988 and 2015. Twenty percent of the polygons obtained from segmentation were visually interpreted and assigned to five land cover classes. We generated a land use transition matrix and used Fourier Transforms to detect trends in variation of landscape mosaics and fragmentation. Results We observed prominent dynamics of the grassland mosaic leading to the homogenization of its structure through decreasing patch heterogeneity, especially on south-facing slopes. Grasslands shifted from open communities to dense pastures, with a reduction of scree and spread of tall grasses. The former trend could be understood as a recovery process reverting screes to conditions in equilibrium with local landform and climatic features, while the invasion of tall grasses is a land-degradation process that might lead to local species extinction and loss of habitat connectivity. Conclusions Pronounced changes in the large-scale landscape characteristics, mainly due to land use changes, of which scientists and managers of protected areas are not fully aware, are underway in the top mountain sectors of the study area

Functional response of an invasive tall grass (Brachypodium genuense) to environmental variability in sub-Mediterranean climate

We found that in more productive conditions (deeper soil, medium/high pH values, northfacing slopes, and “conservative” land forms) populations of B. genuense showed higher SLA, plant height and cover values. This underlies a fast-growing strategy based on high resource acquisition/use rate, as well as higher competitive ability for above-ground resources (e.g. light). The opposite trend emerged for unproductive/dry conditions (southfacing slopes, shallow soils, lower pH values). Under these constraints, SLA, plant height and cover value decreased underlying a slow-growing strategy with high conservation and low acquisition rate of resource. In addition, we found that very high nitrogen amount might have a detrimental effect on B. genuense individuals decreasing the SLA values, thus requiring the plant to change the growth strategy

How modifications of forage features related to inter-annual rainfall variations affect sheep morpho-physiological characteristics

The sub-Mediterranean climate, mostly characterising the mountain regions sited all around the Mediterranean basin, is a variant of the Temperate bioclimate, characterised by winter cold stress and summer drought stress, the intensity and duration of which depend on the elevation gradient and land form factors. Models for the sub-Mediterranean regions indicate a strong increase of summer dry conditions and a more marked inter-seasonal and interannual variability, with maximum changes in summer and minimum changes in winter. We aimed to assess the interplay among plant community characteristics, inter-annual climatic variations and sheep morpho-physiological features to model the responses of sub- Mediterranean pastoral systems to climate change and management modification. We tested the hypothesis that the inter-annual climatic variability affects grassland productivity and feed value with different intensity (depending on slope angle and aspect) and causes variations in sheep rumen features (epithelium keratinisation degree) and animal body state estimated by means of Body Condition Score (BCS) method. We postulated that there is a significant correlation among grassland features, rumen characteristics and animal body state. Results showed that in the sub-Mediterranean climate increased summer drought stress negatively affects forage quantity and quality, and that type and direction of changes are quite different from those reported for both Mediterranean and Temperate regions. In particular, the most negatively affected plant communities were those of productive habitats, which also undergo a strong decrease of the summer forage re-growth ability. These habitats are foundational for the sustainability of extensive sheep farming in sub- Mediterranean mountains, since those of south-facing slopes are normally fully dry in summer. Grasslands of south-facing slopes are more affected by the decrease of latespring/ summer rainfall variation, and by the seasonal rainfall patterns. Changes in forage features, and in particular the increasing fibre amount led to increase the rumen keratinisation. When the degree of keratinisation increases, the absorptive ability decreases, so we can infer that drought intensification reflects in a sheep's lessened ability to absorb nutrients because of increases in the rumen keratinisation degree, negatively affecting also the animal body state. Differences of BCS among years were significant in late summer, which is the mating period for sheep. In the driest year the end-August BCS drops down largely below the value considered sufficient to ensure the animal breeding/milking performances. Reduction of summer rainfall greater than 15–20% compared to the normal average value might be detrimental for semi-extensive rearing sustainability in sub- Mediterranean climate

LONG-TERM ABANDONMENT OF CROPLANDS IN THE SUBMEDITERRANEAN CLIMATE DOES NOT LEAD PER SE TO THE RECOVERY OF THE SEMI-NATURAL HERB COMMUNITIES DEEMED WORTHY OF CONSERVATION IN THE EU HABITATS DIRECTIVE

We found that topographic and soil conditions drive the species assemblage in pastures after crop abandonment, but long-term abandonment does not lead per se to the recovery of the semi-natural grassland communities deemed worthy of conservation in the EEC Directive. This was mainly due to the lack of appropriate disturbance regimes that allows the spread of dominant tall herbs, which, in turn, reduces the site suitability for subordinate plants. Moreover, their spread fosters the presence of elements such as ruderals and fringe species

An updated checklist of the vascular flora of Montagna di Torricchio State Nature Reserve (Marche, Italy)

This study aims to increase floristic knowledge of Marche by means of a survey in the Montagna di Torricchio State Nature Reserve (central Italy). The Reserve, located in the central Apennines, covers about 3.2 km2 at altitudes ranging from 820 to 1,491 m a.s.l. It has been owned and managed as a strict reserve by the University of Camerino since 1970: all the anthropic activities ceased about 50 years ago, except for a minimal area where mowing and cattle grazing are still allowed. The floristic list consists of 789 specific and subspecific taxa belonging to 81 families and 352 genera. Two species are new for Italy (Taraxacum calocarpum and T. pulchrifolium) and 14 for Marche regional flora. Compared to previous floristic studies, we found 127 more taxa but we showed a certain stability in the life-form spectrum, suggesting limited effects of dynamic processes related to climate and land-use changes. The negligible number of alien species (11) is probably related to the limitations to anthropic activities in the Reserve. The occurrence of taxa never recorded for Italy and Marche highlights the floristic value of the Reserve for species conservation in the central Apennines

How soil water availability affects the functional diversity in grazed and abandoned pastures

We analysed patterns of species, traits and functional diversity (FD, Rao’s quadratic entropy) in relation to environmental variables and management type. We found that soil water availability on a fine scale determines FD and direction of trait response after grazing cessation. In plots with bare soil and lower water availability values, species and trait composition were less affected by abandonment. Instead, we observed a shift from strategies devoted to grazing resistance to those devoted to competition for light after grazing cessation at intermediate water availability. Grazing cessation decreased the overall FD, however in both the harsher and more productive conditions grazed and abandoned systems did not show significant differences. Instead, in intermediate conditions we documented significant differences in FD of many trait states, especially those related to resource acquisition and space occupation. Thus, our results indicate that the level of soil water resources determines the net effect of disturbance on the FD of grassland communities