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Questions: Knowledge of how extreme drought events induce plant dieback and, eventually, plant mortality, may improve our forecasting of ecosystem change according to future climate projections, especially in Mediterranean drylands. In them, shrublands are the main vegetation communities in transition areas from a subhumid to semi-arid climate. This study analyzed differences in plant dieback after an unusual drought in 2014 and identified their main underlying factors in relation to three groups of explanatory variables: water availability, soil properties and vegetation structure attributes. Location: Four Mediterranean shrublands along a climatic gradient in SE Spain. Methods: At each experimental field site, we sampled a pool of vegetation structure characteristics, soil depth and soil surface properties, and we also determined water availability by continuously monitoring soil moisture and the microclimate conditions. Results: The climatic analysis showed that there was an extreme drought event in 2014, which was below the first percentile of the driest years. Under such conditions, vegetation dieback occurred at all the study sites. However, plant dieback differed between sites and plant biotypes. Subshrubs were the main affected biotype, with diebacks close to 60% at the driest sites, and up to 40% dieback for shrubs depending on their vertical development. Relative extractable water and bare soil surface cover were the best explanatory variables of plant community dieback but changed between plant biotypes. Vegetation structure variables related to plant vertical development (leaf area index [LAI], plant height, phytovolume) were significant explanatory variables of plant dieback in shrubs, subshrubs and grasses. Consecutive dry days fitted the best model to explain subshrub dieback. Conclusions: We found that rainfall pattern rather than total annual rainfall was the climatic factor that best determined water availability for plants in Mediterranean drylands. These results also pointed out the relevance of plant structure and soil properties for explaining ecosystem responses to extreme drought. This research was funded by the Spanish Ministry of Economy and Competitiveness through Projects HYDROMED (PID2019-111332RB-C21) and INERTIA (PID2019-111332RB-C22), and through the IMAGINA projects (PROMETEU/2019/110) and (APOSTD20/2019–-7956) from the Generalitat Valenciana and the European Social Fund. AMR was supported by the scholarship FPU-UA (2015) from the University of Alicante.

Pathogens that attack invasive plants can positively affect the integrity and functioning of ecosystems. Stem-tip dieback and extensive wilting followed by sudden death have been observed in Chrysanthemoides monilifera subsp. rotundata (bitou bush), one of Australia’s worst invasive shrubs. Metabarcoding and culturing methods were used to investigate whether fungi are implicated in this syndrome. Metabarcoding results revealed significantly different endophytic fungal communities within healthy and diseased bitou bush, and colocated native plants. There was no difference in fungal communities between soil sampled in the root zone of healthy and diseased bitou bush at the same site. Two Diaporthe sp. operational taxonomic units (OTUs), dominant at sites with extensive wilting explained 30% of the similarity between diseased bitou bush across all sites. Two other OTUs, Austropleospora osteospermi and Coprinellus sp., explained 20 and 40% of the similarity between diseased plants, respectively, and were only dominant at sites with dead or stunted, partially defoliated but not wilted bitou bush. A Penicillium sp. OTU explained 90% of the similarity between healthy bitou bush plants. Various Diaporthe spp. dominated isolations from diseased bitou bush. Manipulative experiments confirmed Diaporthe spp. pathogenicity on bitou bush excised and in situ stems. In another experiment, Diaporthe masirevicii infected flowers and, from there, colonized stems endophytically; however, wilting and sudden death of bitou bush did not occur within the experimental timeframe. Our study provides circumstantial evidence that bitou bush sudden death syndrome is the result of a shift in the composition of its endophytic fungal community from mutualist to pathogenic species. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

The results of monitoring studies carried out to identify the features of the current distribution of vegetation and productivity of sandy pasture ecosystems in the south of the European territory of Russia are presented. The objects of research were natural pasture phytocenoses on the territory of the Tsimlyansk sand massif. The methods of ecological and geobotanical surveys were used in the work. Plant samples were collected at key sites located in different wet areas using the 5-fold slope method. To identify dominant and subdominant species of natural phytocenoses, the Drude species abundance assessment scale was used. It was found that the pasture ecosystems of the Tsimlyansk sand massif are characterized by the presence of 58 dominant and subdominant species from 22 families, which occupy a certain position in the herbaceous and shrub communities, depending on the moisture content of the territory. The territory of complete humidification is characterized by the presence of 7 dominants and subdominants from 7 families. In the territory of excessive moisture, 9 species from 7 families dominate in phytocenoses. On the territory of sufficient and variable moisture, 26 species from 8 families predominate in the communities. The territories of moderate humidification are distinguished by the presence in the associations of 22 dominant species from 9 families. The territory of complex moistening, which is insufficient and severely insufficient under sand hills and moderate in the groves, is characterized by the presence of 9 dominant and subdominant species from 6 families in the communities. In 2018-2020 it was revealed that the annual phytomass of the grass and grass communities of the Tsimlyansk sand massif increases from spring to summer (from 91-117 to 204-267 g/m2) and decreases from summer to autumn (from 204-267 to 156-190 g / m2). The average annual productivity of natural phytocenoses is 156-190 g / m2.

Invasions by multiple nonnative species threaten native communities worldwide. We know that interactions among nonnative species influence nonnative success. However, we know relatively less about the influence of community assembly history on the interactions within nonnative species and thereby invasion success. To investigate this, we transplanted seedlings of two highly invasive shrubs, Rosa rubiginosa (hereafter ‘rose’) and Cytisus scoparius (hereafter ‘broom’), at two different times into mesocosm communities of native and nonnative species. We conducted priority and delay treatments that consisted of the early and late arrival of the invasive shrubs, respectively. We gave full priority/delay to each invasive shrub (rose early/late arrival, broom early/late arrival) and simultaneous priority/delay (simultaneous early/late arrival). We predicted that if assembly history were important, the invasive shrubs will benefit from early-arriving and will be disadvantaged by late-arriving and that arriving before the co-invader shrub will be more beneficial than arriving before the rest of the community. We also predicted that assembly history treatments that gave an advantage to invasive shrubs will more negatively affect native species than nonnative species. We found that the invasive shrubs did not benefit by early-arrival, but they were hindered by the early-arrival of the co-invader. The rose paid a high cost for late-arrival, but the broom was only impaired when its late-arrival implied arriving after the rose. Contrary to our predictions, natives paid a lower cost than nonnatives by arriving late. In general, our mesocosm experiment showed that the success of invasive species depended more on not arriving later than other invaders than on arriving early in the community. We suggest that community assembly history modulates the sign and strength of nonnative species interactions whose consideration might improve management practices.

Urban flying-fox camps are a major source of human–wildlife conflict, producing noise, odour, vegetation damage, property damage, and concerns about disease. Although there is a significant demand in many communities for bat camps to be dispersed, there is limited information on how such dispersal can be conducted effectively. Determining the habitat characteristics flying-foxes use when selecting a camp site is key to understanding why they establish camps where they do and to where they might move if dispersed. We characterised little red flying-fox (LRFF) camp habitat at two spatial scales: floristics and vegetation structure at the local scale, and climatic and landscape characteristics at the broad scale. We found weak associations with local-scale tree and shrub height and cover, and stronger associations with increased Normalised Difference Vegetation Index (a measure of ‘greenness’) and decreased distance to nearest watercourse. These relationships were not strong enough to explain all variation in the model, suggesting that there are other factors, such as social cues, that could also influence camp site selection. Our results suggest that minor modifications to existing or proposed camp sites will be unlikely to repel or attract LRFFs, as other factors are likely to play key roles in the formation of camp sites for this species.

A long-term study of a bolster heath–pond system at Newdegate Pass, Mount Field, Tasmania, was designed to test a theory of cyclical dynamics and to determine why there was constancy in the proportions of species in stable mosaic bolster heath, while their individual distributions changed. Groups of permanent plots were monitored approximately once every 5 years between 1983 and 2017, in apparently stable, apparently colonising, apparently recovering and apparently degrading bolster heath. The putatively stable sites exhibited an average of 37% spatial turnover in the three early 5-year periods, with reciprocal replacements between many pairs of species; however, there was little evidence of long-term directional change except for expansion of a gymnosperm shrub across the top of the bolster mosaic at one site. This pattern suggests a cyclical succession of species in the stable mosaic; however, the mechanism driving cyclicity remains unclear, with facilitation, competition and stochastic processes being implicated at different times and locations. These cyclic changes were likely to have been largely endogenous, given the variability and autocorrelations in relative growth rates of the stable mosaic over short horizontal distances, conforming with neutral theory. The process of dam vegetation loss after draining was rapid, as was vegetation colonisation of the floor of one dam and recovery from fire. On a putatively colonising site on rocky ground, changes were subdued but directionally consistent with the previously proposed model, which was consistent with all long-term observations.

SummaryA new species to science of evergreen forest shrub, Kupeantha yabassi M.G.Alvarez & Cheek (Coffeeae - Rubiaceae), is described, illustrated and compared morphologically with the closely similar species K. pentamera. Restricted so far to a single site in evergreen lowland forest near the Ebo Forest, Yabassi, Littoral Region, Cameroon, this species is Critically Endangered using the IUCN 2012 standard due to habitat clearance driven mainly by agriculture, adding to the growing list of threatened species resulting from anthropogenic pressure on Cameroon forests. A revised key to the six species of Kupeantha is presented. Two distinct geographical and ecological species groupings within the genus are identified and discussed. Notes are given on other narrowly endemic and threatened species in the Ebo Forest area, a threatened centre of diversity important for conservation in the Littoral Region.

Designing wildflower habitats to support beneficial insects providing pollination and pest control services is important for supporting sustainable crop production. It is often desirable to support both groups of insects, making the selection of resource plants for insect conservation programs more challenging. Moreover, the process of selecting resource plants is complicated by the array of possible options in each region, and the need to provide resources over the entire growing season. Identifying traits shared by resource plants that are attractive to both bees and natural enemies can reduce the need to evaluate new plants in each region, by providing a guide for the types of plants expected to be rewarding to these insects. Using insect visitation data collected from replicated common garden plantings of native wildflower and shrub species from the Great Lakes region of the United States, we found a high degree of correlation between the abundance of bees and natural enemies visiting native plant species. These results were used to identify a set of 15 plant species that can provide resources for these insects throughout the summer. Across all tested species, pollen quantity per flower and the week of bloom were positively correlated with some, but not all, taxonomic groupings of beneficial insects. In contrast, floral area was consistently positively associated with visitation of both natural enemies and wild bees. This trait is easy to document and can allow for efficient local testing of potential resource plants, providing a faster path to implementing insect conservation in working landscapes.

The quality and quantity of forage available to reproductive female ungulates during the summer can influence body condition and lactation, ultimately influencing herd production. The energetic costs of migration can influence individual fitness, thus understanding the mechanisms that drive some individuals in a partially migratory population to migrate, while others remain on winter range year-round, has important conservation and ecological implications. We examined differences in forage quality and quantity between migratory (n = 19) and resident (n = 17) summer home ranges for a population of mule deer (Odocoileus hemionus) in the John Day Basin of northeast Oregon. During 2018, we collected vegetation measurements three times throughout the summer (mid-May, mid-June, mid-July) to determine changes in dry matter digestibility (DMD; %) at three different phenological stages (emergent, mature, and cured) for three forage classes (grass, shrub, forbs). On the second visit, at the peak of the growing season, we collected biomass and cover data to determine differences in forage quantity for each forage class between the migratory and resident summer ranges. In mid-June 2019, we revisited a subsample of sites (migratory [n = 5]; resident [n = 5]) to estimate interannual variation. Migratory deer had access to overall higher quality forage at higher-elevation summer ranges. Forbs had the highest forage quality on both summer ranges. Forage quality declined across the entire study area as moisture declined and vegetation senesced. Shrub forage quality was higher (DMD = 54.1%) on resident ranges than migratory ranges (49.7%; P = 0.001). Grasses had higher biomass (26.1 Mg/ha) and cover (50.1 %) than forbs (19.2 Mg/ha; 34.7% cover) or shrubs (20.6 Mg/ha; 6.7% cover) across the entire summer range. Overall, migratory deer had access to higher-quality forage throughout the summer, yet resident deer had access to higher-quality shrub browse. This trade-off in forage availability may partially explain the persistence of a partially migratory population as a bet-hedging strategy on a landscape where low moisture availability and episodic drought and disturbance create variable foraging conditions.

Resprouting is an efficient life history strategy by which woody savanna species can recover their aboveground biomass after fire. However, resprouting dynamics after fire and the time it takes to start producing flowers and fruits are still poorly understood, especially for the Brazilian savanna (Cerrado biome), where fire is an important driver of vegetation structure and ecosystem functioning. We investigated the resprouting dynamics and production of flowers and fruits of 26 woody species (20 tree and 6 shrub species for a total of 485 individuals) that were burned and the production of flowers and fruits for a subset of 12 species (139 individuals) in an unburned area in a Brazilian savanna. We classified the species’ resprouting strategies as hypogeal (at the soil level, with main stem death), epigeal (on the main stem or crown), and hypogeal + epigeal. We used generalized linear mixed-effect models to identify the post-fire recovery patterns for five years. Individuals with basal resprouts (hypogeal and hypogeal + epigeal resprouting) produced an average of 6 basal resprouts, but only 33% of resprouts survived after five years. Individuals in burned areas produced fewer flowers and fruits than individuals in unburned areas. At least a subset of individuals in all the resprouting strategies started to produce flowers and fruits in the first-year post-fire. About 68% of the species with hypogeal resprouts produced flowers and fruits in the first-year post-fire, but the intensity of flowering and fruiting was lower compared to individuals with other resprouting strategies over time. Although woody species have invested in post-fire growth and sexual reproduction in all resprouting strategies, the long time needed to recover these processes can make these species more vulnerable to frequent fires.

Live shrubs in forest understories pose a challenge for mitigating wildfire risk with prescribed fire. Factors driving shrub consumption in prescribed fires are variable and difficult to explain. This study investigated spatial patterns and drivers of Sierra Nevada mixed-conifer forest shrub consumption in prescribed fires through analysis of high-resolution imagery taken before and after prescribed fire. We applied a spatially explicit, generalized additive model to assess tree cover and coarse woody material as potential drivers of shrub consumption. Shrub cover in two experimental stands prior to burning was 38% and 59% and was 36% and 45% one-year post-burn. In both stands shrub patch density increased, while area-weighted mean patch size and largest patch index decreased. Increased local percent cover of coarse woody material was associated with increased shrub consumption. These findings provide information for prescribed fire managers to help better anticipate shrub consumption and patchiness outcomes under similar conditions.

Screw tree (Helicteres isora) is a shrub species (Fam: Malvaceae) with 1.5–4 m in height and with multi-main trunks up to 9–12. In Indonesia, kayu ules has been used as a traditional medicine, known as jamu, and has been commercialized. In order to cultivate this species, vegetative propagation is likely promising compared to the generative propagation since seed viability is low and cannot be stored for longterm. Nevertheless, there is a lack of information on which diameter classes, media types and light intensities would give the best result for vegetative propagation. This research aimed to obtain information on which diameter classes and media that were suitable for kayu ules stem cutting propagation and to what degree the light intensity would be best for the growth of the seedlings of kayu ules. Three diameter classes and four media types were employed in a complete random design under the greenhouse environment. Three months old good quality vegetatively-propagated seedlings were transplanted under two light intensities (under transparent canopy and shading net). The result showed that considering the factor of diameter classes and media in kayu ules stem cutting propagation, it had improved the survival of the stem cutting. Diameter class I was best grown in media type 3 with 46.67 ± 12.2 % of survival rate, diameter class II was best grown in media type 2 with 38.67 ± 11.6 % of survival rate, whereas diameter class III was best grown in media type 4 with 52 ± 6.9 % of survival rate. The transplanted seedlings also grew significantly better under transparent canopy with higher light intensity. The distinctive features of screw tree under shading net were wider leaf area, higher specific leaf area and relative water content but it was lower in above ground dry biomass compared to the kayu ules under transparent canopy.

Surface fuel loads are highly variable in many wildland settings, which can have many important ecological effects, especially during a wildland fire. This variability is not well described by a single metric (e.g. mean load), so quantifying traits such as variability, continuity and spatial arrangement will help more precisely describe surface fuels. This study measured surface fuel variability in the northern Sierra Nevada of California following a high-severity fire that converted a mixed-conifer forest to shrub-dominant vegetation, both before and after a subsequent shrub removal treatment conducted as site preparation for reforestation. Data were collected on vegetation composition, spatial arrangement and biomass load of the common surface fuel components (1–1000-h woody fuel, litter, duff and shrubs). Mean shrub patch length decreased significantly from 9.25 to 1.0 m and mean dead and down surface fuel load decreased significantly from 131.4 to 73.4 Mg ha−1. Additionally, probability of encountering a continuous high fuel load segment decreased after treatment. This work demonstrates a method of quantifying important spatial characteristics of surface fuel that could be used in the next generation of fire behaviour models and provides metrics that land managers may consider when designing post-fire reforestation treatments.

An understorey shrub is an extreme CaOx accumulator that plays a disproportionately large role in Ca cycling; however, transformations of CaOx and other Ca forms in forest soils demand detailed attention. Calcium oxalate (CaOx) plays an important but neglected role in Ca cycling in terrestrial ecosystems. CaOx crystals are present in leaves and roots (less commonly in bark and wood) of many trees and vary greatly in size, shape, and crystallinity. We extend an Australian study of an Eucalyptus regnans forest ecosystem, showing that the shrub Pomaderris aspera plays a significant role in Ca cycling. X-ray fluorescence microscopy (XFM) shows that crystals of CaOx in the leaves of both species contain up to 15% Ca; the density of crystals being much greater in P. aspera than in E. regnans. The concentration of oxalate in P. aspera is about 6% dry weight, ranking P. aspera as an extreme oxalate accumulator, in common with a number of other members of the family Rhamnaceae. The fate of CaOx in nutrient cycling is poorly known and often misunderstood. Upon committal of CaOx to the soil, transformations are brought about by fire or saprophytic heterotrophic bacteria and fungi; the latter derive carbon and energy from the oxidation of oxalate. The primary reaction is one of the oxidations which produces CaCO3 and CO2, such that half of the C is sequestered in the CaCO3 which will remain stable under alkaline conditions and is therefore a potential sink for atmospheric CO2.

Investigation of relationships between biomass of different plant compartments is important because their varying turnover rates affect the amount and composition of aboveground and belowground litter, which has a direct effect on nutrient cycling and carbon accumulation in soil. A study of biomass partitioning amongst compartments of the bilberry (Vaccinium myrtillus L.), a common clonal dwarf shrub in boreal coniferous forests, was carried out at eleven study sites in Finland. We hypothesize that the biomass partitioning of bilberry follows a common pattern across a variety of edaphic conditions and geographic range, and this pattern can be modelled by the rank distribution of compartment biomasses. We found that the highest portion of the total biomass belonged to rhizomes, which were followed by shoot stems, roots and leaves. Furthermore, this pattern was observed regardless of the latitudinal zone (northern or southern Finland), site fertility level measured as soil C/N ratio and canopy-dominant tree species (pine or spruce). However, the observed ratios between biomass compartments varied between different sites. In particular, we found that the exact ratio between above- and belowground biomass was dependent on the C/N ratio of the soil organic layer (exponential model, R2 = 0.443), showing that bilberry allocates more biomass to belowground parts in the nutrient poor than in the nutrient-rich sites. The results suggested that there are uniform regularities in the structural organization within the plant species representing clonal growth form of dwarf shrubs. This observation enables us to use the rank distribution of compartments in modelling biomass partitioning of bilberry in a wide range of environmental conditions, although the mechanisms underlying such regularities require further investigation.

Background Traditional knowledge is key for sustainability, but it is rapidly disappearing. Pig keeping in forests and marshes is an ancient, once widespread, now vanishing practice, with a major economic and ecological potential. The knowledge of pig keepers and the foraging activity of pigs are hardly documented. Methods We studied the knowledge of traditional pig keepers (svinjars) on wild plants and pig foraging on the Sava-Bosut forest-marsh complex in Serbia. We conducted picture-based interviews about 234 locally common and/or salient plant species, and participatory fieldwork (11 days) and visual observation (21 days) on pig foraging. Results 181 wild plant species were known by svinjars and 106 taxa were consumed by pigs. Svinjars knew well and could name most regularly foraged species. 98 species were reported by svinjars as foraged and 56 as not eaten. 28 species were observed by the authors as eaten regularly, while 21 were nibbled and 17 avoided. Contradictory information on foraging was rare both among svinjars (8 species) and between svinjars and researchers (7 species); several of these species were rare. Leaves of 92, fruits or seeds of 21 and ‘roots’ of 20 species were reported or observed as eaten, usually with high seasonality. Svinjars were overall observant, but knew little about some less salient species (e.g. Veronica, Circaea). The most common forages (reported and/or observed) were fruits (Quercus, fleshy fruits), grasses (Agrostis, Glyceria), herbs (Ranunculus ficaria, Circaea), nutritious ‘roots’ (Carex spp., Iris), young shrub leaves (Crataegus, Carpinus) and ‘tame’ plants growing in the sun (Persicaria dubia, Erigeron annuus). Traditional, now extinct pig breeds were reported as less selective and more ‘knowledgeable’ about plants, as they received less additional fodder. Svinjars learnt their knowledge since childhood, from community members, but long-term personal observations and everyday encounters with pigs were also important sources of knowledge. Conclusions A deeper understanding of pig foraging could contribute to using pigs in nature conservation management, resource management and organic farming, and to a better understanding of wild boar foraging. The knowledge of svinjars is a disappearing intangible cultural heritage of European importance. Knowledge holders deserve recognition, and legal and financial support to continue this tradition.

White‐tailed deer (Odocoileus virginianus) populations have recovered to about 30 million animals in the United States, but land cover has changed during the interval of recovery. To address the relationship between deer densities and current land cover at regional scales, I applied random forests and extreme gradient boosting classifiers to model low and high deer density classes, at two different thresholds (5.8 and 11.6 deer/km2), and land classes in three regions during approximately 2003. For low and high deer density classes divided at 5.8 deer/km2, deciduous broadleaf forest overall was the most influential and positive variable in the central east and central regions and crop and pasture were the most influential and negative variables in the southeast region. Deer density increased with area of deciduous and mixed forests, woody wetlands, and shrub in all regions. Deer density decreased with area of crop, developed open space, and developed low and medium residential density in all regions. For density classes divided at 11.6 deer/km2, deer density had the strongest relationship with woody wetlands in the central east region, mixed and deciduous forest in the southeast region, and woody wetlands and herbaceous vegetation in the central region. Deer density increased with deciduous and mixed forests, woody wetlands, and shrub in all regions. Conversely, deer density decreased with herbaceous vegetation, crop, and developed low residential densities in all regions. Therefore, at regional scales, deer overall occurred at greater densities in forests and woody wetlands and lower densities in agricultural and residential development, which did not appear to support more deer. Deer preference for forests does result in damage to forest products, but alternatively, some may consider that deer provide important socioeconomic and ecological services by reducing number of small trees, particularly in the absence of other disturbances that historically controlled tree biomass., At regional scales, deer occurred at greater densities in forests and lower densities in agricultural and residential development, which did not improve habitat by supporting more deer. Deer preference for forests does result in damage to forest products. However, deer provide important socioeconomic and ecological services by reducing number of small trees, particularly in the absence of other disturbances that historically controlled tree biomass.

The interspecific plant interactions along grazing and aridity stress gradients represent a major research issue in plant ecology. However, the combined effects of these two factors on plant–plant interactions have been poorly studied in the northeast of Iran. To fill this knowledge gap, 144 plots were established in 12 study sites with different grazing intensities (high vs. low) and climatic characteristics (arid vs. semiarid) in northeastern Iran. A dominant shrub, Artemisia kopetdaghensis, was selected as the model species. Further, we studied changes in plant life strategies along the combined grazing and aridity stress gradients. In this study, we used relative interaction indices calculated for species richness, Shannon diversity, and species cover to determine plant–plant interactions using linear mixed‐effect models (LMM). The indicator species analysis was used to identify the indicator species for the undercanopy of shrub and for the adjacent open areas. The combined effects of grazing and aridity affected the plant–plant interactions and plant life strategies (CSR) of indicator species. A. kopetdaghensis showed the highest facilitation effect under high stress conditions (high grazing, high aridity), which turned into competition under the low stress conditions (low grazing, low aridity). In the arid region, the canopy of the shrub protected ruderals, annual forbs, and grasses in both high and low grazing intensities. In the semiarid region and high grazing intensity (low aridity/high grazing), the shrubs protected mostly perennial forbs with C‐strategy. Our findings highlight the importance of context‐dependent shrub management to restore the vegetation damaged by the intensive grazing., The manuscript is based on a field study, aiming to compare the canopy effects of an unpalatable dominant shrub (Artemisia kopetdaghensis) in the conditions of biotic stress, represented by intensive grazing and abiotic stress, represented by severe aridity. Our results bring new evidence to the current debate on the relative importance and characteristics of plant–plant interactions along the gradients of environmental stress. We detected the facilitative effects of the dominant shrub on species diversity in the presence of both grazing and aridity. However, the facilitative effects turned into competition in the conditions of less severe aridity in the semiarid region.

Plateau pika burrows are common feature of degraded grassland in the Qinghai–Tibet Plateau (QTP) and serve as an important indicator of pika activity and grassland degradation. However, the current understanding of the spatial pattern changes of pika burrows and their critical thresholds across a degradation gradient in alpine grassland is deficient. In this study, we investigated and quantified changes in the spatial pattern of plateau pika burrows under typical degraded alpine shrub meadows in the northeastern QTP using an unmanned aerial vehicle and landscape pattern metrics. The degradation of the alpine shrub meadow leads to a change in landscape pattern from a two‐layered structure of alpine shrub and alpine meadow to a mosaic of alpine meadow and bare soil, with plateau pika burrows scattered throughout. Moderate degradation is the tipping point for changes in surface landscape patterns, followed by the disappearance of alpine shrub, the retreat of alpine meadows and the encroachment of bare soil, and the increasing density and size of pika burrows. The area characteristics of alpine meadows have influenced changes in the spatial pattern of pika burrow, and maintaining its proportional area is a vital measure to control the threat of pika burrows to pastures. The results of this paper provide a methodological reference and guidance for the sustainable utilization of grassland on the QTP., UAV‐based spatial pattern survey of plateau pika burrows. Negative effect of alpine meadow area ratio on pika burrow density. Spatial pattern characteristics of pika burrows will support grassland management.

Fire is considered a critical process for limiting shrub encroachment and maintaining grassland structure and functions. Fire can be detrimental to grasses in upland settings of arid desert grasslands, but no studies have been performed in more productive swale grasslands. Monitoring of a prescribed fire treatment in a swale grassland in southern New Mexico indicated that perennial grasses had not recovered after 5 years, even with above-average rainfall. Furthermore, indicators of erosion susceptibility increased, and shrubs resprouted rapidly.

Montane amphibians are vulnerable to environmental and climatic changes. Species response to these changes can be better understood by analyzing how amphibian communities differ along environmental gradients. We utilized both taxonomic and functional approaches to determine patterns of distribution in montane amphibians in the southern Philippines. We tested habitat variables to explain distribution and filtering of montane amphibian traits from lowland evergreen to upper montane forests. We recorded 24 species of amphibians from seven families. Multivariate tests revealed different species composition of montane amphibians among forest types. Amphibian diversity decreased and endemism increased from lowland evergreen to upper montane forest. Elevation, shrub foliar cover, and tree basal area explained most of the variations in amphibian distribution. Species richness decreased with these habitat variables while abundance decreased with shrub foliar cover. Fourth-corner modeling showed that elevation had the strongest effect on traits, particularly those related to habitat use, larval ecology, and resource acquisition. Our results suggest that both functional traits and environment were interacting in driving the pattern of montane amphibian distribution, highlighting the additive value of incorporating functional traits in understanding amphibian distribution patterns and community assembly mechanisms.

Radial growth of high-elevation shrubs shows the high sensitivity to climate in dry regions, providing new evidence for drought-mediated dynamics of alpine woody plants. In mountains, shrubs forming their uppermost distributional limits (shrubline) are highly sensitive to increasing cold limitations upwards. However, the constraints imposed by a shorter growing season due to lower temperatures upslope could interact with drought stress in mountainous regions. Here, we aim to investigate that question by comparing radial growth patterns of shrubs in wet (forest region of Nangqian County, BZ hereafter) vs. dry (forest region of Leiwuqi County, LWQ hereafter) regions located on the eastern Tibetan plateau. Considering the climate trend in this area towards warmer and drier conditions, we hypothesize that growth of high-elevation shrubs will be mainly limited by low summer temperatures under sufficient soil moisture. To test this hypothesis, we collected ring-width data from 123 alpine shrubs (Salix oritrepha Schneid.) along an altitudinal gradient from 4200 to 4600 m a.s.l. Dendroecological analyses showed that shrub growth was positively related to mean June or July temperature during the past decades in both wet (BZ) and dry (LWQ) regions regardless of site elevation. By contrast, correlations between shrub growth and seasonal precipitation were not significant. Shrub growth trends were positive before 2010 but turned negative afterwards. Overall, radial growth of shrubs along the altitudinal gradients up to the shrubline could shift from being temperature to moisture limited if warming-induced drought stress intensifies.

Key message Lowered pollen and seed quality of B. humilis compared to its widespread tree relatives may threaten its populations at the southwestern edge of the species range. Abstract Inability to produce vital propagules is the main threat to the persistence of rare plants at the edges of species distribution. In the present investigation, factors responsible for the low germinability of shrub birch (Betula humilis) seeds in the peripheral populations were analysed. As shrub birch populations are found in phosphorus (P)-limited peatlands with high groundwater levels, the impact of groundwater PO43− ion contents and groundwater table for B. humilis flowering was also studied. Qualities of the B. humilis seeds and pollen were compared to those of tree congeners silver birch (B. pendula) and downy birch (B. pubescens), which usually represent a high reproductive performance. We revealed that the poor germination ability of B. humilis seeds was caused by the high proportions of empty seeds (44.8%) and seeds with partially developed embryos (47.3%). The insufficient numbers of viable seeds may be a consequence of low-quality shrub birch pollen, as only 1.6% of pollen grains sprouted. The germinability of shrub birch pollen was significantly lower than that of Betula tree pollen; thus, there is a risk of pollination of B. humilis female flowers by pollen grains of tree birches. Positive relationships between the P concentrations in seeds and seed germinability were revealed in tree birches, but not in B. humilis. The availability of PO43− ions in the groundwater did not affect B. humilis flowering, but male inflorescences were more numerous in stands with higher groundwater levels. Consequently, the maintenance of peatlands is crucial for the efficient sexual reproduction of shrub birches.

For many species, facilitation can result in transient species coexistence, but subsequent competition can limit long-term coexistence. Adaptive phenotypic variation in response to increased competition following facilitation, however, could be a means of prolonging coexistence, although this hypothesis remains largely unexplored. Resprouting shrubs following fire in Mediterranean heathlands facilitate seedling establishment and growth of subshrub species such as the carnivorous plant Drosophyllum lusitanicum. Nevertheless, shrub canopies interfere with prey capture by established D. lusitanicum plants, potentially reducing fitness with increasing time since fire. At three heathland sites in southwestern Spain, we examined the relationship between stem morphology and shrub canopy cover to determine whether D. lusitanicum exhibited vertical or horizontal elongation to avoid shade or interference with prey capture. We also quantified individual performance responses (e.g., survival, growth, flower production) as a function of stem morphology and size of D. lusitanicum plants and shrub canopy cover. Adult plants of D. lusitanicum showed greater vertical elongation with increasing shrub canopy cover. Small adult plants showed an increased likelihood of flowering with increasing shrub canopy cover. The number of flowers produced by flowering plants decreased with vertical elongation when shrub cover was low. We illustrate how coexistence of foundational shrubs and D. lusitanicum could be maintained by a combination of facilitation of D. lusitanicum seedlings and small adults by shrubs and adaptive changes in stem morphology in established individuals to avoid shrub interference, allowing the replenishment of a fire-regulated, persistent seed bank.

Coastal freshwater wetlands (CFWs) are among the most understudied wetlands globally and are highly vulnerable to projected climate changes. To address CFW knowledge gaps in south-east Queensland, Australia, we surveyed the floristic composition and structure of wooded CFWs and explored variation in vegetation patterns in relation to selected environmental drivers. Understorey and shrub assemblages were surveyed using a cover-class scale and stem counts for tree species abundance. Vegetation structure attributes (stem density, basal area) were calculated from survey data. Redundancy analysis was used to investigate drivers of vegetation structure and the species composition of each stratum. Vegetation structure patterns were associated with gradients of rainfall, soil moisture, salinity and pH. Understorey species composition was associated with wallum wetland species, native perennial grass and herb species, and vegetation patterns of the canopy. Common CFW species, namely Melaleuca quinquenervia and Eucalyptus tereticornis, dominated tree assemblage variation. Overall, CFW vegetation exhibited strong associations with gradients of salinity, rainfall, groundwater dependence and disturbance. Alterations to key drivers of vegetation pattern with future climate changes are likely to markedly influence the composition, structure and function of CFW vegetation communities. Action is therefore required to maintain CFW vegetation communities and ecological function in these diverse and unique wetland systems.

Adesmia bijuga Phil. is an endemic and endangered shrub species of central Chile. Its potential shade intolerance is one of the leading hypotheses for its vigor loss when the species grows beneath closed canopies. The objective of this study was to assess the growth and physiological acclimation to the shade of young plants of A. bijuga. A nursery experiment was established with three light levels based on the interception of photosynthetic active radiation (PAR) (TRT0: control at full sun; TRT60: 60% shaded; TRT90: 90% shaded), and maintained for 71 days during the summer season. Growth and leaf morpho-physiological responses were evaluated at the beginning, at the middle, and at the end of the experiment. The shading treatment increased plant height (H), live crown percentage (Lcrown), and specific leaf area (SLA) compared to the control treatment at full sun. However, light-saturated photosynthetic rate (Amax), dark respiration rate (Rd), and light compensation point (Γi) were higher in TRT60 than in the other treatments, while no differences were found among treatments for the apparent quantum yield (α). At this stage of plant development, our results suggest high acclimation plasticity of A. bijuga to light levels; however, a semi-shade environment (i.e., TRT60) favored a better performance of the species.

Plant-derived carbon (C) inputs via foliar litter, root litter and root exudates are key drivers of soil organic C stocks. However, the responses of these three input pathways to climate warming have rarely been studied in alpine shrublands. By employing a 3-year warming experiment (increased by 1.3 °C), we investigated the effects of warming on the relative C contributions from foliar litter, root litter and root exudates from Sibiraea angustata, a dominant shrub species in an alpine shrubland on the eastern Qinghai-Tibetan Plateau. The soil organic C inputs from foliar litter, root litter and root exudates were 77.45, 90.58 and 26.94 g C m−2, respectively. Warming only slightly increased the soil organic C inputs from foliar litter and root litter by 8.04 and 11.13 g C m−2, but significantly increased the root exudate C input by 15.40 g C m−2. Warming significantly increased the relative C contributions of root exudates to total C inputs by 4.6% but slightly decreased those of foliar litter and root litter by 2.5% and 2.1%, respectively. Our results highlight that climate warming may stimulate plant-derived C inputs into soils mainly through root exudates rather than litter in alpine shrublands on the Qinghai-Tibetan Plateau.

Net ecosystem CO2 exchange is the result of net carbon uptake by plant photosynthesis and carbon loss by soil and plant respiration. Temperature increases due to climate change can modify the equilibrium between these fluxes and trigger ecosystem-climate feedbacks that can accelerate climate warming. As these dynamics have not been well studied in dry shrublands, we subjected a Mediterranean shrubland to a 10-year night-time temperature manipulation experiment that analyzed ecosystem carbon fluxes associated with dominant shrub species, together with several plant parameters related to leaf photosynthesis, leaf morphology, and canopy structure. Under moderate night-time warming (+0.9°C minimum daily temperature, no significant reduction in soil moisture), Cistus monspeliensis formed shoots with more leaves that were relatively larger and denser canopies that supported higher plant-level photosynthesis rates. Given that ecosystem respiration was not affected, this change in canopy morphology led to a significant enhancement in net ecosystem exchange (+47% at midday). The observed changes in shoot and canopy morphology were attributed to the improved nutritional state of the warmed plants, primarily due to changes in nitrogen cycling and higher nitrogen resorption efficiency in senescent leaves. Our results show that modifications in plant morphology triggered by moderate warming affected ecosystem CO2 fluxes, providing the first evidence for enhanced daytime carbon uptake in a dry shrubland ecosystem under experimental warming.

There is a significant knowledge gap in the area of management of the vast shelterbelt network currently existing on agricultural lands in Canada and across the world. Throughout eight decades of shelterbelt planting in Saskatchewan, Canada, there are no available records of shelterbelt management practices used by land managers, such as herbicides (H), fertilizers (F), irrigation (I), or tillage (T) applications, collectively referred to as HFIT management. The main objective of this large-scale study was to quantify the effects of HFIT management on shelterbelt carbon sequestration for six common tree and shrub species. Field data from 303 randomly selected shelterbelts across millions of hectares of agricultural land in three soil zones were combined with existing shelterbelt carbon stock curves for Saskatchewan, produced by a shelterbelt carbon management support tool, Belt-CaT, to estimate site-specific total ecosystem carbon (TEC) stocks. Estimated TEC stocks and annual rates for HFIT sites were compared to the no management sites used as a reference. HFIT management increased carbon stocks for the majority of species, four of six, resulting in higher TEC at any tree spacing, mostly at higher suitability sites. However, HFIT management effects were not consistent across individual species, land suitability, or planting designs. The top three HFIT management combinations for hybrid poplar were IT, HIT, and HI, for white spruce they were FT, IT, and FIT, and only FT benefited caragana shelterbelts. The lack of management practices makes unmanaged shelterbelts more unpredictable and unreliable, in terms of tree growth and carbon stocks sequestration potential.

We studied the impact of flooding and light availability gradients on sexual and asexual reproduction in Lindera melissifolia (Walt.) Blume, an endangered shrub found in floodplain forests of the Mississippi Alluvial Valley (MAV), USA. A water impoundment facility was used to control the duration of soil flooding (0, 45, or 90 days), and shade houses were used to control light availability (high = 72%, intermediate = 33%, or low = 2% of ambient light) received by L. melissifolia established on native soil of the MAV. Sexual reproductive intensity, as measured by inflorescence bud count, fruit set, and drupe production, was greatest in the absence of soil flooding. Ninety days of soil flooding in the year prior to anthesis decreased inflorescence bud counts, and 45 days of soil flooding in the year of anthesis lessened fruit set and drupe production. Inflorescence bud development was the greatest in environments of intermediate light, decreased in high‐light environments, and was absent in low light environments. But low fruit set diminished drupe production in intermediate light environments as compared to high light environments. Asexual reproduction, as measured by development of new ramets, was greatest in the absence of soil flooding and where plants were grown in high or intermediate light. Plants exhibited plasticity in reproductive mode such that soil flooding increased the relative importance of asexual reproduction. The high light environment was most favorable to sexual reproduction, and reproductive mode transitioned to exclusively asexual in the low light environment. Our results raise several implications important to active management for the conservation of this imperiled plant., We studied the impact of flooding and light availability gradients on sexual and asexual reproduction in Lindera melissifolia (Walt.) Blume, an endangered shrub found in floodplain forests of the Mississippi Alluvial Valley, USA. Plants exhibited plasticity in reproductive mode such that soil flooding increased the relative importance of asexual reproduction. The high light environment was most favorable to sexual reproduction, and reproductive mode transitioned to exclusively asexual in the low light environment.

Analizamos 103 censos de vegetación de la Estepa Magallánica Seca, un área de 12000 km2 de estepas graminosas semiáridas en el SE de la Patagonia. Los objetivos del presente trabajo fueron ampliar el relevamiento de vegetación de la región, clasificar las principales comunidades, interpretarlas en función de Modelos de Estados y Transiciones (MEyT), cartografiar su distribución espacial y buscar evidencias de posibles transiciones mediante análisis de contrastes de alambrado. El análisis de conglomerados definió 10 comunidades vegetales, algunas de las cuales no estaban contempladas en el MEyT previo, por lo que fue necesario generar un nuevo MEyT. Este modelo incluye transiciones ya descriptas previamente, en las que la erosión expone horizontes Bt y genera condiciones favorables a Estepas Subarbustivas, pero además, otras en las cuales se acumulan sedimentos que favorecen a Pappostipa chrysophylla, una gramínea psamófila invasora. Tres estados que se diferenciaban en el modelo anterior por cambios reversibles de cobertura de pastos cortos fueron combinados para reflejar solamente transiciones irreversibles. Para la cartografía se trazaron polígonos alrededor de cada censo sobre imágenes satelitales LANDSAT, se combinaron de acuerdo con el análisis de agrupamiento, se obtuvieron firmas espectrales, se clasificaron y se agruparon las clases del mapa en cinco estados. La precisión del mapa fue mayor al 61%. El 39% del área correspondió a Coironales en buena condición de conservación, dominantes al sur. Le siguen en importancia las Estepas Subarbustivas con P. chrysophylla (18%) y las Estepas Subarbustivas (15%), ambas degradadas. Los contrastes de alambrados evidenciaron transiciones que habían sido hipotetizadas en el modelo, como las que llevaron a Estepas Subarbustivas degradadas asociadas probablemente a un pastoreo de invernada intenso previo. El mapa y el MEyT que se presentan en este trabajo permiten interpretar mejor la dinámica de la Estepa Magallánica Seca, una de las áreas ecológicas más diversas y productivas de la Patagonia, que muestra extensas áreas degradadas. Estos pastizales deberían ser protegidos en el futuro, ya que no existen prácticamente áreas de conservación. En este sentido, toda la región debería ser conservada por medio de un manejo de cargas ganaderas moderadas y descansos que aseguren el mantenimiento de la biodiversidad, productividad y servicios ecosistémicos. We analyzed 103 vegetation relevés in the Dry Magellan Steppe, a 12000 km2 semiarid biozone (170-270 mm of annual rainfall) dominated by grass steppes in the SE of Patagonia. The objective was to map rangeland states within the State and Transition Model (STM). Cluster analysis showed 10 communities, some of them not included in previous STM models of the region, so that a new model was designed. In addition to already described transitions such as those driven by erosion that exposes argilic soil horizons covered by dwarf Shrub Steppes, the new model includes transitions driven by eroded soil accumulation that benefit Pappostipa chrysophylla, an invasive psammophyle grass species. Three states previously differentiated by short grass cover were combined in order to reflect only irreversible transitions. Maps were obtained by drawing polygons around each relevé, grouping them in accordance to the classes defined by cluster analysis and extracting spectral firms of these areas in a Landsat 8 image. These classes were grouped into five states. We estimated 61% precision of the map. Tussock grasslands in good conservation state occupied 39% and were dominant in the south of the area. Degraded dwarf shrub steppes with P. chrysophylla (18%) and dwarf shrub steppes (15%) were next in importance. Fence contrasts in the map show some of the hypothesized transitions, such as those that lead to dwarf shrub or dwarf shrubs with P. chrysophylla in highly grazed wintering areas in the north. The map and new STM will help to interpret the dynamics of the Magellan Steppe, one of the most diverse and productive biozones of Patagonia that shows clear evidence of past degradation. Some of these rangelands should probably be protected in the future, as conservation areas are almost nonexistent. In this sense, all of the region should be conserved in productive units by managing grazing with moderate stocking rates and rests in order to ensure conservation of biodiversity, productivity and other ecosystem services. EEA Santa Cruz Fil: Schenkel, Cintia Anahí. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Fil: Oliva, Gabriel Esteban. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Fil: Oliva, Gabriel Esteban. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina. Fil: Paredes, Paula Natalia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Fil: Humano, Gervasio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Fil: Ferrante, Daniela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Fil: Ferrante, Daniela. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; Argentina.

Facilitation is a global phenomenon that occurs when one species promotes the growth, survival, or reproduction of another species, mostly in stressful environments. However, the importance of facilitation by shrubs in maintaining plant community diversity is not well evaluated in the Himalayas, especially for the richness and conservation of medicinal and human-valued species. Therefore, we aimed to explore the facilitative role of a dwarf shrub species, Berberis angulosa, in maintaining plant composition and richness of human-valued species in the Langtang valley of Nepal's Himalayas. We censused plant species in open patches and beneath Berberis during monsoon and post-monsoon (dry) seasons at three elevations. Total species richness and richness of human-valued species were significantly higher inside the Berberis canopy than in gaps; the former being 39% and the latter 46% greater under shrubs than in open sites. Facilitation by Berberis shrubs promoted plant community diversity irrespective of season and elevation; however, higher differences in mean species richness for both total plant species and human-valued species during the dry season and at high elevation indicated increased facilitation intensity under more stressful conditions. The facilitative effect of Berberis shrubs increased, combining both seasons, overall plant diversity by 19% (total=105), and human-valued species by 16% (total=56). Our results show the importance of facilitation by nurse shrubs in structuring plant communities and protecting medicinal and socio-ecologically important plants, thus enriching ecosystem services in the Himalayas. These results suggest nurse plant species should be incorporated into conservation policies and management strategies for effective biodiversity conservation and sustainability, especially in the face of climate change.

A long-term drought has led to the mass mortality of shrubs in the semi-arid Israeli Negev. The most impacted shrub species is the Noaea mucronata (Forssk.) Asch. and Schweinf. In a four-year study, we found that herbaceous vegetation growth was greater in the dead shrub patches than in the surrounding inter-patch biocrusted spaces, suggesting that the dead shrub patches encompass improved micro-habitats. However, unexpectedly, the soil moisture in the dead shrub patches was consistently lower than that of the inter-patch biocrusted spaces. At the same time, soil quality in the dead shrub patches was higher than that in the inter-patch spaces. Therefore, it seems that the overall better soil conditions in the dead patches overcome the scarcity of soil-water, supporting increased herbaceous productivity. For explaining the discrepancy between herbaceous vegetation and soil-water, we formulated a conceptual framework, which highlights the key factors that regulate soil-water dynamics in this dryland ecosystem. We demonstrate that herbaceous vegetation is facilitated in the dead shrub patches by a legacy effect that takes place long after the shrubs have died. The dead shrub patches encompass a unique form of ecosystem engineering. The study highlights the complex and unpredicted impacts of prolonged droughts on dryland ecosystems.

Water is the main limiting factor for groundwater-dependent ecosystems (GDEs) in drylands. Predicted climate change (precipitation reductions and temperature increases) and anthropogenic activities such as groundwater drawdown jeopardise the functioning of these ecosystems, presenting new challenges for their management. We developed a trait-based analysis to examine the spatiotemporal variability in the ecophysiology of Ziziphus lotus, a long-lived phreatophyte that dominates one of the few terrestrial GDEs of semiarid regions in Europe. We assessed morpho-functional traits and stem water potential along a naturally occurring gradient of depth-to-groundwater (DTGW, 2–25 m) in a coastal aquifer, and throughout the species-growing season. Increasing DTGW and salinity negatively affected photosynthetic and transpiration rates, increasing plant water stress (lower predawn and midday water potential), and positively affected Huber value (sapwood cross-sectional area per leaf area), reducing leaf area and likely, plant hydraulic demand. However, the species showed greater salt-tolerance at shallow depths. Despite groundwater characteristics, higher atmospheric evaporative demand in the study area, which occurred in summer, fostered higher transpiration rates and water stress, and promoted carbon assimilation and water loss more intensively at shallow water tables. This multiple-trait analysis allowed us to identify plant ecophysiological thresholds related to the increase in salinity, but mostly in DTGW (13 m), and in the evaporative demand during the growing season. These findings highlight the existence of tipping points in the functioning of a long-lived phreatophyte in drylands and can contribute to the sustainable management of GDEs in southern Europe, paving the way for further studies on phreatophytic species. Supplementary Information The online version contains supplementary material available at 10.1007/s00442-021-04993-w.

Seed predation may influence community assembly and invasion dynamics when seed predators preferentially select some seed species over others. However, the role of different seed predators and their preferences for seeds in multiple ecological contexts, including the endangered California sage scrub ecosystem, remain unresolved making predictions about which processes limit or promote invasions difficult. In addition, selection criteria, specifically how seed size and biogeographic origin (native versus invasive) influences selection, requires further research across multiple granivore guilds. We examined seed predator preference for common native and invasive seeds across small and large seed classes using seed dish experiments with motion-sensor video observation. We also quantified the relative importance of ants, birds, and mammals as seed predators in sage scrub. Community-wide, granivores preferred the small-seeded invasive mustard Brassica nigra, avoided the large-seeded invasive grass Bromus rubens and the native large-seeded shrub Encelia californica, and did not show significant selection or avoidance for the small-seeded native shrub Salvia apiana. Birds, notably California towhees (Melozone crissalis), were the most frequent granivore while rodents and ants rarely removed seeds. This study reveals that birds are important seed predators in California sage scrub and have the potential to contribute to biotic resistance to mustard invasions (Brassica nigra and potentially others).

Mountain ecosystems are considered to be sensitive to global change and human disturbance. Our retrospective analysis of archival aerial imagery showed dynamics of arctic-alpine tundra vegetation in the Krkonose Mountains, Czech Republic; image classification revealed a change in land cover classes in 44% of the study area over the past eighty years. This particular ecosystem holds many rare features, such as high numbers of endemic, glacial relict and rare species as well as relict geomorphological components such as sorted patterned ground. Our study revealed an accelerating expansion of the native and planted shrub, Pinus mugo, from 30.6% of the study area in 1936 to 48.6% in 2018, mostly at the expense of grasslands that decreased from 59.3% in 1936 to 44.2% in 2018. Shrub expansion represents a threat to relict periglacial landforms, covering 8% of the sorted patterned ground in 1936 and 26.5% in 2018. Shrub encroachment was shown to be due to artificial planting of the pine in the past as well as the cessation of former farming (mowing and cattle grazing) and, most probably, also by global change. Both dwarf pine stands and tundra grasslands hold high conservation value (Natura 2000 habitats); a balance between different nature protection interests must, therefore, be ensured. Detailed spatio-temporally, explicit outputs of the remote sensing analysis can serve as a baseline for nature conservation in order to prepare corresponding management plans.