Mountain Grasslands Research Articles

Estimating aboveground biomass of grassland in central Asia mountainous areas using unmanned aerial vehicle vegetation indices and image textures – A case study of typical grassland in Tajikistan

Climate change and human activities have severely impacted Central Asia's mountainous grasslands' health status, making monitoring aboveground biomass (AGB) crucial for grassland protection. However, a high-resolution and low-cost solution for AGB monitoring is lacking for Central Asia's grassland. This research proposes an unmanned aerial vehicle (UAV) based AGB monitoring framework using consumer-level cameras. Texture features from UAV RGB images and vegetation indices from UAV multispectral images are used to predict AGB. As one of the typical mountainous countries in Central Asia, Tajikistan is chosen as the study area. Four different grassland types were chosen to investigate the performance of applying UAV for AGB monitoring. Firstly, correlation analysis was performed to identify important features for AGB estimation. Subsequently, the ground-measured AGB and UAV image features were utilized in multiple linear regression (MLR) and generalized additive model (GAM) to develop an AGB prediction model. The results show that the angular second moment (ASM) of the green band and green normalized difference vegetation index (GNDVI) are the two most important features for AGB estimation in the study area. Furthermore, the GAM-based model demonstrated higher accuracy (R2 = 0.87, RMSE = 127.53 g/m2, rRMSE = 0.17) compared to MLR (R2 = 0.74, RMSE = 181.68 g/m2, rRMSE = 0.24), highlighting the nonlinear relationship between AGB and UAV image features. This research uses multispectral and RGB images to achieve a high accuracy and efficient AGB monitoring framework for Central Asia grasslands and provides a reference to validate satellite images for providing long-term and large-scale monitoring of grassland ecosystems and reasonable utilization of grassland resources.

Nutrient addition alters plant community productivity but not the species diversity of a mountain meadow in Tajikistan.

Tajikistan is a typical mountainous country covered by different mountain grasslands that are important pasture resources. Recently, grassland degradation has become widespread due to climate change and human activities and fertilization has been used to improve grassland production. However, fertilizer inputs can substantially alter species diversity, but it is uncl\ear how productivity and species diversity respond to nutrient enrichment in the mountain meadows of Tajikistan. Therefore, a 5-year (2018-2022) continuous in-situ mineral fertilizer experiment was conducted to examine the effects of three nitrogen (N) levels (0, 30, and 90kg N ha-1 year-1), two phosphorus (P) levels (0 and 30kg P ha-1 year-1), and their combinations on above-ground biomass (AGB) and species diversity in a mountain meadow grassland in Ziddi, Varzob region, Tajikistan. Five species diversity metrics-Margalef's species richness (Dma), the Shannon-Wiener index (H), the Simpson index (C), Pielou's equitability index (Epi), and the Evar Species Evenness index (Evar)-were used to measure species diversity. The results indicated that the addition of different N and P amounts and their various combinations considerably increased both total and dominant species AGB, with the highest increase occurring in the N90P30 (90kg N ha-1 year-1 combined with 30kg P ha-1 year-1) treatment in 2022; during the experiment, the importance value of Prangos pabularia (dominant species) first decreased and then increased, but its dominant status did not change or fluctuate among the years. Furthermore, N, P, and their different combinations had no significant effect on species diversity (Dma, H, C, Epi, and Evar). All the species diversity indexes fluctuated among years, but there was no interaction with mineral fertilizer addition. Total AGB had a negative relationship with species diversity and low concentration N fertilizer addition (N30; P30) strengthened this negative trend. However, this trend decreased under the high N fertilizer condition (N90P30). Overall, nutrient addition to the natural mountain grassland of the Varzob region improved AGB, which meant that there was more forage for local animals. Mineral fertilizers had no significant effect on species diversity, but may enhance P. pabularia dominance in the future, which will help maintain the stability of the plant community and improve the quality of the forage because P. pabularia is an excellent and important winter fodder. Our study suggests that scientific nutrient management could effectively promote grassland production, conserve plant variety, and regenerate degraded grassland, which will counteract the desertification process in northwest Tajikistan mountain meadows.

Climate change is threatening mountain grasslands and their cultural ecosystem services

Mountain grasslands are widespread ecosystems worldwide that provide economic and cultural ecosystem services. They serve as a source of food, carbon sequestration, clean water, and habitat, also hosting traditional practices such as transhumance. However, they are facing growing threats due to climate change, including extreme weather events like intensified rainfall causing soil erosion and prolonged droughts alongside high temperatures, impacting vegetation health and water resource management. Despite their strategic importance, there remains a gap in the comprehensive global mapping of these ecosystems and an exhaustive exploration of the critical challenges posed by climate change. In this context, we present an unprecedented satellite-based global mapping of mountain grasslands and conduct an analysis focusing on key climate change-related concerns. This includes an assessment of (1) soil erosion by water under diverse climate scenarios (RUSLE; 2015 vs. 2070-RCP8.5) and (2) the dynamics of extreme drought and high-temperature events (utilizing the Vegetation Health Index; VHI), with a specific focus on European mountain grasslands during the summer of 2022. Our findings indicate a potential future global aggravation of soil erosion in mountain grasslands (+2.3%), particularly in South America (+19.4%) and Africa (+10.0%), as well as localized hotspots. Furthermore, our analysis of the 2022 situation in Europe demonstrates the extensive impact of similar extreme events across a significant portion of grassland areas at a continental scale, with notable hotspots observed in southern Europe. Finally, we explore strategies to enhance mountain grassland management, specifically focusing on nature-based solutions (NbS) aimed at preserving their invaluable cultural ecosystem services in the face of climate change.

The update and ecological status of the flora of the Belezma National Park, Algeria

Abstract. Benchouala A, Bekdouche F, Si Bachir A. 2023. The update and ecological status of the flora of the Belezma National Park, Algeria. Biodiversitas 24: 6134-6150. The establishment of national parks and nature-protected areas helps to conserve biodiversity. The conservation and enhancement of the floristic diversity of the Belezma National Park (BNP), Algeria which is also designated as biosphere reserve, require precise knowledge of its flora. To that end, the inventory conducted at BNP at the level of forest massifs, preforests, and mountain grasslands enabled us to identify 562 taxa belonging to 342 genera and 93 families, with a predominance of Asteraceae, Poaceae, and Fabaceae. Based on biological spectrum, hemicryptophytes outnumbers other life forms by 44.4%. Zoochory is the most common distribution mode among inventoried species (44.3%). The Mediterranean type dominates the chronological spectrum with proportion of 45.9%. Endemism is represented by 53 species (9.4% of the total flora). According to executive decree No. 12-03 of January 4, 2012, the BNP flora consists of 196 rare species, including 34 endemic species and 26 threatened and protected ones in Algeria. Based on our results, it has been possible to constitute a database of the BNP flora, useful for its protection.

Effects of Environmental Factors on Plant Productivity in the Mountain Grassland of the Mountain Zebra National Park, Eastern Cape, South Africa

The relationship between plant productivity, measured according to biomass and species richness, is a fundamental focal point in community ecology, as it provides the basis for understanding plant responses or adaptive strategies. Although studies have been conducted on plant biomass and environmental factors, research concerning mountainous grassland areas is scarce. Therefore, the aim of the present study was to examine the influence of environmental factors on aboveground plant biomass in the mountainous grassland of the Mountain Zebra National Park, South Africa. Biomass distribution was uneven within the park, owing to certain species having relatively higher biomass values. These differences may be attributed to the chemical and physical properties of the soil, including carbon and nitrogen content, soil pH, and soil texture (sand, silt, and coarse fragments). A disc pasture meter was used to collect biomass data. Multiple regression analysis revealed that most environmental factors did not significantly influence plant biomass. The only environmental factor influencing plant biomass was soil pH; the influences of other factors were not statistically significant. The results of this study elucidate the interactions of environmental factors with plant biomass. Future research could investigate how environmental factors influence plant biomass, both below and above the ground in mountainous grassland.

Compositional Characteristics, Fatty Acid Profile, Phenolic Content and Volatile Organic Compounds (VOCs) of Feta Cheese Made in Mountainous Grasslands and Plains of Greece

The study aimed to compare the physicochemical composition, fatty acid profile, phenolic content and volatile organic compounds (VOCs) of feta cheese produced in two regions in Greece (mountainous grasslands and plains). The VOC profiles of forage in the mountainous grasslands were also investigated in order to detect any relationship between the two profiles. Forbs were found to be the major functional group in the mountainous area and the most abundant VOCs were aldehydes, alcohols, and terpenes. Significant variations were observed between the main compositional features of the two types of cheeses, with the cheese produced from the milk of ewes and goats grazing in the mountainous region having a higher moisture content, lower fat content, and higher protein content. A total of 34 VOCs were identified and the most abundant groups in the cheese samples were esters, hydrocarbons, and alcohols. The fatty acid profile, phenolic content, and terpene profile of the cheese were also affected by the type of pasture. The cheese produced from the milk of ewes and goats grazing in the mountainous region also had a higher content of conjugated linoleic acid (CLA) and a lower content of saturated fatty acids (SFAs). These findings suggest that the grasslands grazed by ewes and goats in the mountainous region have a positive impact on the nutritional quality of feta cheese.

Effects of Spring Phenology on Grassland Growth in Qilian Mountains Across Multiple Spatiotemporal Scales

AbstractInvestigating the differences in grassland growth and its response to advancing spring phenology and climate change across various spatiotemporal scales is crucial for the sustainable development of alpine mountain regions under a warming and wetting climate. This study analyzed the growth dynamics of grassland in the Qilian Mountains from 2000 to 2019 at seasonal and periodic scales. Using partial wavelet coherency and partial correlation analysis, we investigated the influence of temperature, precipitation, and spring phenology on grassland growth. Additionally, we quantified the dominant factors affecting grassland growth in different ecological zones and elevational gradient. The results indicated that the mean normalized difference vegetation index increased at an average rate of 1.1 and 2.8 × 10−3/year for grassland in spring and summer, respectively. Furthermore, the start of vegetation growing season (SOS) has advanced 6.0 days during 2000–2019. The dominant factor for grassland growth shifted from spring temperature to summer precipitation. The importance of SOS ranked second, significantly influencing 29.3% and 25.1% of grassland during spring and summer, respectively. Grasslands situated above 4,000 m above sea level (ASL) were more sensitive to climate change, with SOS exerting the greatest influence within the elevation range of 2,800–4,000 m ASL. Additionally, the phase difference in the time‐frequency scale of partial wavelet coherency revealed a lag effect of approximately 1 month for summer grassland growth to respond to precipitation. These findings can provide a scientific basis for optimizing global vegetation models and predicting the productivity of alpine mountain grasslands.

Positive and negative plant−plant interactions influence seedling establishment at both high and low elevations

Deciphering how plants interact with each other across environmental gradients is important to understand plant community assembly, as well as potential future plant responses to environmental change. Plant−plant interactions are expected to shift from predominantly negative (i.e. competition) to predominantly positive (i.e. facilitation) along gradients of environmental severity. However, most experiments examine the net effects of interactions by growing plants in either the presence or absence of neighbours, thereby neglecting the interplay of both negative and positive effects acting simultaneously within communities. To partially unravel these effects, we tested how the seedling establishment of 10 mountain grassland plants varied in the presence versus absence of plant communities at two sites along an elevation gradient. We created a third experimental treatment (using plastic plant mats to mimic surrounding vegetation) that retained the main hypothesised benefits of plant neighbours (microsite amelioration), while reducing a key negative effect (competition for soil resources). In contrast to our expectations, we found evidence for net positive effects of vegetation at the low elevation site, and net negative effects at the high elevation site. Interestingly, the negative effects of plant neighbours at high elevation were driven by high establishment rates of low elevation grasses in bare soil plots. At both sites, establishment rates were highest in artificial vegetation (after excluding two low elevation grasses at the high elevation site), indicating that positive effects of above-ground vegetation are partially offset by their negative effects. Our results demonstrate that both competition and facilitation act jointly to affect community structure across environmental gradients, while emphasising that competition can be strong also at higher elevations in temperate mountain regions. Consequently, plant−plant interactions are likely to influence the establishment of new, and persistence of resident, species in mountain plant communities as environments change.

Impacts of Grazing on Vegetation and Soil Physicochemical Properties in Northern Yinshan Mountain Grasslands

The grasslands at the northern foot of the Yinshan Mountains are an integral component of the northern grassland ecosystem in China. The ecosystem in this region has low stability and poor resistance to disturbance. In this study, experiments were conducted to evaluate the possible changes in vegetation community structure and soil physicochemical properties due to overgrazing in the grasslands. Completely randomized group experiments were designed with grazing intensity as the single-factor study was conducted using natural grassland located in Xilamuren (in Inner Mongolia, northern China) as the study area. Three blocks were created, each having four plots of different grazing intensities and each block having an area of 100 m × 100 m. The experiments were conducted to evaluate the possible variances both in the structure of the vegetation community and the soil physicochemical properties resulting from overgrazing in the grasslands at the northern foot of Yinshan Mountain. The results were as follows: The importance values of dominant species, such as Heteropappus altaicus and Artimisia gmelinii, exhibited varying degrees of change with an increase in the grazing intensity. The surface vegetation cover decreased significantly with an increase in the grazing intensity. The increasing grazing intensity led to a significant increase in the content of very coarse sand grains in the soil. Severe grazing increased the exposed surface area, intensified the effects of blowing wind and scouring action of water, and led to the coarsening of topsoil particles. At 0–5 cm depth, the bulk density of soil exhibited an increasing tendency with an increase in the grazing intensity. The organic matter content of the soil in the heavily grazed plots decreased by 11.74%, 11.00%, and 14.08%, respectively, when compared to that in the 0–40 cm soil layer with no grazing, light grazing, and moderate grazing. The results emphasized the importance of managing grazing intensity for soil and vegetation restoration. Thus, the effects of short-term grazing (for example, 5 years) on vegetation community composition and species diversity may be less pronounced. This study contributes to our understanding of pasture management and the restoration of grassland species diversity.

Isotopic insights into the Early Acheulean (1.95 Ma–1.66 Ma) high-elevation paleoenvironments at Melka Kunture (Upper Awash Valley, Ethiopia)

In this paper, we present stable carbon and oxygen isotope analyses of fauna tooth enamel from Garba IVD (1.95 Ma) and Gombore IB (1.66 Ma), two Early Acheulean sites of Melka Kunture (Upper Awash, Ethiopia), and discuss faunal taxonomy and fossil pollen. Our aim is to infer the diet and habitat of the fossil fauna, as well as the environment of both sites, in order to provide a broader paleoecological reconstruction. During the Pleistocene, the vegetation of the highlands of Ethiopia belonged to the Dry evergreen Afromontane Forest and grassland complex, which is distinct from the savanna of lower elevations in eastern Africa. Our carbon isotopic results indicate that all the analyzed faunal taxa were grazers consuming C4 plants, whereas oxygen isotopic results discriminate the taxa according to their semiaquatic or terrestrial habitats. These results are consistent with the taxonomic composition of the faunal assemblages and the palynological results, suggesting extended mountain grasslands in the landscape at Garba IVD. In contrast, the carbon isotopic results do not totally agree with the pollen paleoenvironmental reconstruction at Gombore IB, where the open vegetation was interrupted by forests and bushy vegetation. Stable isotope and pollen data provide different outcomes (feeding strategies vs. nearby plants) and have different temporal and spatial resolutions. This is relevant when reconstructing past environments by using independent proxies. Furthermore, isotopic comparisons with other Early Pleistocene paleontological and archaeological sites from eastern Africa indicate that all the analyzed taxa in common fed on C4 plants and that their dietary strategies were not affected by variations linked to the difference in elevations.

Variation in reproductive success in a fragmented Meadow Pipit population: a role for vegetation succession?

Most farmland birds experience strong declines across Europe. These declines are typically associated with agricultural intensification but research on alternative local causes remains scarce. We investigated variation in reproductive success as a potential driver for the observed population declines in a fragmented population of the Meadow Pipit Anthus pratensis, a representative inhabitant of extensively managed mountain grasslands across Europe. Intense nest surveys in the entire Meadow Pipit metapopulation of the Northern Black Forest (SW Germany) between 2020 and 2022 provided information on reproductive success for 53 females distributed across nine habitat patches along an 18 km ridge of the Northern Black Forest. Hatching dates delayed by approx. 5.0 days per 100 m altitude and were almost 10 days later in a year with cold and rainy spring weather. Mean reproductive success per female and year (3.45 fledglings) was low compared to literature values (approx. 4.5) and may thus drive ongoing population declines. Mayfield nest survival estimates (approx. 51% across the nesting period) were comparably high, with most nest failures linked with predation or adverse weather. Low reproductive success further associated with comparably small clutch sizes and low fractions of second broods in habitat patches characterized by homogeneously dense swards. We suggest that restoration through extensive permanent cattle grazing coupled with succession control may be a key factor to increase population productivity.

Impact of Mountain Grassland Management on Groundwater Recharge in the Polish Carpathians

Impact of Mountain Grassland Management on Groundwater Recharge in the Polish Carpathians

Genetic diversity and runs of homozygosity analysis of Hetian sheep populations revealed by Illumina Ovine SNP50K BeadChip

Hetian sheep have a long history and a wide distribution. They are renowned for their carpet-grade wool, which makes them a valuable genetic resource in China. The survey revealed that Hetian sheep primarily inhabit three distinct ecological environments: mountains (MTS), mountain–grasslands (MGTS), and grasslands (GTS). To understand the evolutionary relationships and germplasm characteristics of Hetian sheep in these diverse environments, we randomly selected 84 healthy adult ewes from each of these ecological regions. We obtained the Illumina Ovine SNP50K BeadChip by extracting DNA from Hetian sheep ear tissue using the phenol-chloroform method. Afterward, we conducted a population genetic structure and genetic diversity analysis of Hetian sheep using the Illumina Ovine SNP50K Beadchip. Principal component analysis (PCA) and neighbor-joining (NJ) phylogenetic analysis indicated that Hetian sheep in three different ecological environments exhibit distinct genetic distances. Admixture analysis indicated that MGTS and GTS share a common ancestral origins. Additionally, the linkage disequilibrium (LD) analysis indicated that M had the highest decay rate, while MG had the lowest decay rate. Furthermore, we identified the overlapping homozygous genomic regions of Hetian sheep in the three ecological environments through runs of homozygosity (ROH) analysis. We subsequently performed gene annotation and enrichment analysis on these overlapping genomic regions. In the MTS environment, we identified 31 candidate genes associated with high-altitude environmental adaptation. These genes are involved in bone cell generation, differentiation, and the maintenance of bone homeostasis (WNT6, WNT10A, and CHSY1); tooth and tongue development (LEF1, TP63, and PRDM16); and hearing and visual functions (RBP4, ATF6, and JAG1). In the GTS environment, we identified 22 candidate genes related to economic traits, including those associated with reproduction (PLA2G4F, ACVR1, and ADCY2) and growth (CAPN3, YAP1, and FGF9). Research indicates that Hetian sheep can be divided at the genomic level into three subtypes: MTS, MGTS, and GTS. This enhances the genetic diversity of Hetian sheep germplasm resources and provides guidance for the conservation of Hetian sheep breeds. Additionally, we have identified genes related to multiparous traits in MGTS and GTS, offering insights for the selection and breeding of multiparous Hetian sheep.

Incipient reshaping of the critical zone of native mountain grasslands caused by exotic pines

Incipient reshaping of the critical zone of native mountain grasslands caused by exotic pines

Monitoring immediate post-fire vegetation dynamics of tropical mountain grasslands using phenocameras

The growing incidence of uncontrolled wildfires all over the globe has called for urgent close monitoring of fire events, awareness, prevention, and management approaches. Phenocameras, ground sensors for monitoring plant phenology by taking sequential RGB digital images, can be an accessible and accurate tool for identifying, monitoring, and analyzing fire events and vegetation recovery. Here, we evaluated the application of an RGB camera system as a methodological approach to monitor and assess the post-fire recovery of a tropical mountain grasslands, the Brazilian campo rupestre. Using camera-derived vegetation indices, we investigated the immediate post-fire regrowth, and short-term post-fire leafing among four vegetation types: wet grassland, peatbog, stony grassland, and rocky outcrop. We recorded significant variations in the post-fire recovery among the grassy vegetation types. The results indicated that fire represents an important driver of leafing dynamics by shortening the length of post-fire growing seasons. The phenological metric of growing season length (GSL) indicated a full post-fire ecosystem recovery in the third year after the fire. The green-up index represented well the dynamics of post-fire vegetation regrowth and recovery across the landscape. Phenocameras rapidly detected fire occurrence and post-fire vegetation responses across vegetation types, demonstrating their significant application in the fire ecology of grassy ecosystems. The accessible, low-cost, and easy-to-setup camera system allows the application of near-remote phenology as a monitoring system and an indicator of vegetation recovery, which may improve restoration and management plans, promoting the conservation of the highly diverse campo rupestre grassland ecosystems.

Substantial Reduction in Vegetation Photosynthesis Capacity during Compound Droughts in the Three-River Headwaters Region, China

Solar-induced chlorophyll fluorescence (SIF) is a reliable proxy for vegetative photosynthesis and is commonly used to characterize responses to drought. However, there is limited research regarding the use of multiple high-resolution SIF datasets to analyze reactions to atmospheric drought and soil drought, especially within mountain grassland ecosystems. In this study, we used three types of high-spatial-resolution SIF datasets (0.05°), coupled with meteorological and soil moisture datasets, to investigate the characteristics of atmospheric, soil, and compound drought types. We centered this investigation on the years spanning 2001–2020 in the Three-River Headwaters Region (TRHR). Our findings indicate that the TRHR experienced a combination of atmospheric drying and soil wetting due to increases in the standardized saturation vapor pressure deficit index (SVPDI) and standardized soil moisture index (SSMI). In the growing season, atmospheric drought was mainly distributed in the southern and eastern parts of the TRHR (reaching 1.7 months/year), while soil drought mainly occurred in the eastern parts of the TRHR (reaching 2 months/year). Compound drought tended to occur in the southern and eastern parts of the TRHR and trended upward during 2001–2020. All three SIF datasets consistently revealed robust photosynthetic activity in the southern and eastern parts of the TRHR, with SIF values generally exceeding 0.2 mW· m−2·nm−1·sr−1. Overall, the rise in SIF between 2001 and 2020 corresponds to enhanced greening of TRHR vegetation. Vegetation photosynthesis was found to be limited in July, attributable to a high vapor pressure deficit and low soil moisture. In the response of CSIF data to a drought event, compound drought (SVPDI ≥ 1 and SSMI ≤ −1) caused a decline of up to 14.52% in SIF across the source region of the Yellow River (eastern TRHR), while individual atmospheric drought and soil drought events caused decreases of only 5.06% and 8.88%, respectively. The additional effect of SIF produced by compound drought outweighed that of atmospheric drought as opposed to soil drought, suggesting that soil moisture predominantly governs vegetation growth in the TRHR. The reduction in vegetation photosynthesis capacity commonly occurring in July, characterized by a simultaneously high vapor pressure deficit and low soil moisture, was more pronounced in Yellow River’s source region as well. Compound drought conditions more significantly reduce SIF compared to singular drought events. Soil drought evidently played a greater role in vegetation growth stress than atmospheric drought in the TRHR via the additional effects of compound drought.

Long-term grazing improved soil chemical properties and benefited community traits under climatic influence in an alpine typical steppe

Grazing and climate change both contribute to diversity loss and productivity fluctuations. Sensitive climate conditions and long-term grazing activities have a profound influence on community change, particularly in high-altitude mountain grassland ecosystems. However, knowledge about the role of long-term continuous grazing management on diversity, productivity and the regulation mechanisms in fragile grassland ecosystems is still rudimentary. We conducted a long-term grazing experiment on an alpine typical steppe in the Qilian Mountains to assess effects of grazing intensity on soil, diversity, productivity and the regulation mechanisms. Plants and soil were sampled along grazing gradients at different distances from the pasture entrance (0, 0.3, 0.6, 0.9, 1.2 and 1.5 km) under the non-growing (WP) and the growing season grazing pasture (SAP). The results revealed that community diversity and biomass did not change significantly on a time scale, while the concentration of soil organic carbon and total phosphorus increased significantly. Heavy grazing (0–0.3 km) decreased community diversity and biomass. Grazing increased soil chemical properties in heavy grazed areas of WP, while the opposite was recorded in SAP. Soil chemical properties explained the largest variances in community diversity and community biomass. The prediction model indicates that grazing in WP mainly affects community diversity through soil chemical properties, and promotes a positive correlation between community diversity and community biomass; in SAP, the direct effect of grazing gradients on community diversity and biomass is the main pathway, but not eliminating the single positive relationship between diversity and biomass, which means that diversity can still be used as a potential resource to promote productivity improvement. Therefore, we should focus on the regulation of soil chemical properties in WP, such as the health and quality of soil, strengthening its ability to store water, sequester carbon and increase nutrients; focus on the management of livestock in SAP, including providing fertilizer and sowing to increase diversity and production in heavily grazed regions and reducing grazing pressure through regional rotational grazing. Ultimately, we call for strengthening the stability and sustainability of ecosystems through targeted and active human intervention in ecologically sensitive areas to cope with future grazing pressures and climate disturbances.

No detectable upper limit when predicting soil mineral-associated organic carbon stabilization capacity in temperate grassland of Central Argentina mountains

Soil organic carbon (SOC) is the major active organic carbon (OC) reservoir within terrestrial ecosystems. SOC is stored in different soil organic matter fractions, among which mineral-associated organic matter is considered the more stable. It has been proposed that the OC stored in this fraction (i.e., MAOC-mineral associated organic carbon) depends on the proportion of fine soil particles. This idea has been challenged by studies that found soils with significantly higher MAOC values than predicted by several models. We assessed the soil MAOC contents in central Argentina mountain grasslands. These soils store high OC contents, and thus may constitute a valuable case to evaluate the soils' saturation behavior. We compared the actual soil MAOC content of these mountain grasslands with the predictions from different MAOC saturation models, and we explored if there were indications of saturation behavior by: a) plotting the MAOC against the total SOC contents, and b) by plotting the OC contents in the fine fraction against the fine soil particles content. We found a positive relationship between MAOC and the fine particle content in the soils studied. However, we also found that even the model with the highest upper limit of MAOC stabilization underestimated the MAOC contents of these grasslands. In addition, we found the absence of an inflection point when plotting the MAOC against total SOC contents. Finally, we observed a weak but significant negative relationship between the concentration of OC in the fine fraction and the proportion of the fine fraction of the soil, with high OC loading values in the coarser soils. These last patterns could be indicators of non-saturation behavior. Our results provide additional evidence that many of the models currently used for predicting the OC saturation deficit of soils may be underestimating the potential MAOC stabilization capacity of certain soils. Additionally, our findings contribute to the evidence challenging the ideas of OC saturation on a fine soil particles basis. We highlight some lines of research that should be developed to confirm the existence of a MAOC saturation behavior, as well as to continue exploring the drivers of OC accrual in different systems.

Polystichum lionelii (Dryopteridaceae), a new Andean species from northwestern Argentina

Polystichum lionelii, a new fern species from the Andean mountain grasslands of northwestern Argentina, is described and illustrated. It is morphologically well differentiated from the other species occurring in the region, showing some relationships especially with P. pycnolepis particularly by the morphology of the pinnules. However, the new species differs from the latter in significant characters, the rhizome scales are ovate to ovate-lanceolate, the basal petiole scales are concolorous, and lamina with filiform scales and multicellular hairs on the abaxial side. An identification key to all Polystichum taxa currently known to occur in the northwestern Argentina is presented.

Climate change and management intensity alter spatial distribution and abundance of P mineralizing bacteria and arbuscular mycorrhizal fungi in mountainous grassland soils

In mountainous grasslands management adaptations are required to maintain soil functions. We investigated climate change (CC) and management effects on the abundance and potential activity of microbiota catalyzing the major steps of P transformation which are still unknown in these grasslands.Soil samples were taken from intact plant-soil mesocosms managed extensively or intensively (two vs. five mowing and slurry applications, respectively). These mesocosms were previously translocated from high to lower altitudes to simulate two CC scenarios (CC1: +1 °C warming and mean annual precipitation (MAP) of 1347 mm and CC2: +3 °C warming and MAP of 956 mm), while control mesocosms (CC0) were relocated at their original site (6 °C and MAP of 1400 mm). Specific marker genes for P-solubilization (gcd), P-mineralization (phoN, phoD, phnX and appA), P-uptake (pitA and pstS), total bacteria and arbuscular mycorrhizal fungi (AMF) were quantified by quantitative real-time PCR. Spatial distributions of phosphatase activities were analyzed in situ by zymography analysis and total organic C, N and P contents were measured.Gene abundances and enzymatic activities were comparable for both managements under CC0, except for phytase-harboring (appA) microbiota which decreased under intensive management. The abundance of microbiota which catalyzes organic P (Po) mineralization (phoN and appA) and those harboring quinoprotein glucose dehydrogenase (gcd) for P solubilization significantly dropped by interacting effects of CC2 and extensive management. The same effect was found for microbes harboring specific P transporters (pitA and pstS). Under intensive management, microbiota catalyzing Po mineralization (phoN and appA), and alkaline phosphatase activities tended to increase in CC2. Noteworthy, the AMF abundance was reduced at 0–5 cm soil depth under CC. Our results suggest that CC and extensive management reduced microbial P solubilization, mineralization and uptake, while management intensification may increase P availability, which leads to shifts in nutrient stoichiometry and decreased AMF abundance.