Dwarf Shrub Species Research Articles

Dendrochronology and extreme climate signals recorded in seven Icelandic shrubs: A multi-species approach in the sub-Arctic

Iceland, located in the climatologically sensitive subarctic zone, is one of the key areas for studying climate change and the current Arctic warming. Poor and rich heathland covers approximately 30% of Iceland, with heath vegetation being the area’s most important vegetation type. Prostrate and erect dwarf shrub and shrub species are the primary sources of dendrochronological information on the changes and characteristics of Iceland’s climate. Here, we investigate the dendrochronological potential of seven common Icelandic heathland species (Dryas octopetala, Calluna vulgaris, Salix arctica, Salix herbacea, Empetrum nigrum, Juniperus communis nana, and Betula nana) and explore the impact of climate conditions on their growth, particularly with regard to extreme meteorological events. We conducted comparative analyses among species and observed their climatic responses in a climatically, morphologically, and geologically homogeneous setting in north-eastern Iceland. After sampling, measurements, and cross-dating, we constructed local chronologies for the seven species. Of approximately 200 samples, only 113 were included in the final shrub chronologies. All chronologies covered at least 50 years, with few of them exceeding 100 years. Dendroclimatological analysis indicated that above-average temperatures in June and summer positively influence the growth of D. octopetala (June–September), J. communis (July–August), B. nana (July–August), C. vulgaris (June–August), and S. arctica (August–September). The opposite is observed for S. herbacea and E. nigrum. Climate–growth correlations indicate that the growth of these species is negatively correlated with temperature and positively correlated with winter and summer precipitation. Furthermore, among the long-lived woody species growing in Iceland, seven common species were used to assess the impact of extreme meteorological conditions on their growth. The most pronounced extreme year in the wood anatomy of Icelandic shrubs was 1979, depicted as very narrow or missing rings and as the blue ring in J. communis.

Annual ring widths in the arctic-alpine dwarf-shrub species Betula Nana — Dataset from long-term alpine ecosystem research in Central Norway (LTAER-NO)

Here we present a Data Paper with microscopically measured data on ring widths of the arctic-alpine dwarf shrub species Betula nana L. from Central Norway. We intend to continuously update the dataset in the future with further ring width measurements of this widespread shrub species.

Adaptation of dwarf shrubs to Arctic tundra conditions in West Svalbard

The stability of the biota in the Arctic regions under climate change and increasing anthropogenic burdens is influenced by the adaptive potential of its representatives. This study aimed to assess the adaptive potential of dwarf shrubs (Betula nana, Vaccinium uliginosum, and Salix polaris) in the flora of West Svalbard on the basis of their morphological and anatomical features and total leaf lipid fatty acid content. All species have similar leaf anatomy characteristics: small leaves, dorsoventral structure with clear differentiation into palisade and spongy mesophyll, which ensures their growth in the Arctic. However, S. polaris is characterized by high volumes of the stomatal apparatus, an amphistomatic type of leaf, a high palisade coefficient, a large volume of mechanical leaf tissue, and a high content of unsaturated fatty acids (UFA). These features provide high functional activity, passage through all stages of ontogenesis, and a wide distribution of the species in West Svalbard. In contrast to S. polaris, B. nana and V. uliginosum are characterized by a decrease in leaf area, a decrease in the palisade coefficient, and a hypostomatic leaf type, which, combined with an increase in the diversity of “secondary” UFA, as well as the lack of generative development, may indicate a higher level pressure of extreme conditions for the species. Thus, these features may explain their limited representation in the ecotopes of West Svalbard. In contrast to B. nana and V. uliginosum, the higher adaptive potential of S. polaris ensures its greater stability in conditions of changing habitat. All studied dwarf shrub species can be used as markers for monitoring the environment in the high Arctic.

Forb stability, dwarf shrub stability and species asynchrony regulate ecosystem stability along an experimental precipitation gradient in a semi-arid desert grassland.

Precipitation pattern changes may affect plant biodiversity, which could impact ecosystem stability. However, the effects of changes in precipitation regime on ecosystem stability and their potential mechanisms are still unclear. We conducted a 3-year field manipulation experiment with five precipitation treatments (-40%, -20%, 0% (CK), +20% and +40% of ambient growing season precipitation) in a semi-arid desert grassland to examine the effects of precipitation alterations on functional group stability, species asynchrony, and diversity, and the underlying mchanisms of ecosystem stability using structural equation modelling. Alterations in precipitation had different effects on community biomass and functional group biomass. Moreover, ecosystem stability was mainly driven by forb stability (path coefficient = 0.79). Changes in precipitation had significant effects on soil dissolved inorganic N (P < 0.01) further affecting ecosystem stability through species asynchrony (path coefficient = 0.25). Dwarf shrubs had a stabilizing effect on ecosystem stability (path coefficient = 0.32), mainly via deep roots. Ecosystem stability tended to be lower in the -40% (4.72) and +40% (2.74) precipitation treatments. The common reduction in species asynchrony and stability of forb and dwarf shrub functional groups resulted in lower ecosystem stability under the -40% treatment. The lower stability under the +40% treatment might be ascribed to unimproved dwarf shrub stability. Higher dwarf shrub and forb stability contributed to higher ecosystem stability under normal precipitation changes (±20% treatments) and CK. Species diversity was not a crucial driver of ecosystem stability. Our results indicate that precipitation alteration can regulate ecosystem stability via functional group stability (e.g. forb stability, dwarf shrub stability) and species asynchrony in a semiarid desert grassland.

Dynamics of radioactive contamination of lingonberry (Vaccinium vitis-idaea L.) in the forests of Zhytomyr Polissia (Ukraine) since the Chernobyl Nuclear Accident

The article presents results of study of levels of radioactive soil contamination and 137Cs activity concentration in the aboveground part of lingonberry (Vaccinium vitis-idaea L.) phytomass and berries on permanent experimental plots in different years since the Chernobyl Nuclear Power Plant accident (forest site type conditions — moist fairly infertile pine site type (B3), soils — soddy-podzolic sandy-loam on fluvioglacial sands). The research was conducted at the Poliskyi Branch of the Ukrainian Research Institute of Forestry and Forest Melioration named after G.M. Vysotsky over the years 1998–2021, utilized methods generally accepted in forest science and radioecology were used. Results were processed using statistical analysis. To substantiate the research, an official reporting data from forestry enterprises of the Volyn, Rivne and Zhytomyr regions were used. An analytical review of the state of research on this problem revealed that at the last 10–15 years there were no scientific publications on the study of 137Cs contamination of lingonberry. It was demonstrated that there was significant reduction in the density of radioactive soil contamination and 137Cs activity concentration in the aboveground part of lingonberry phytomass and berries in the forests of the research region over the observation period. It was found that the main part of the total 137Cs activity is currently located in the upper (10 cm) layer of the mineral part of the soil — 74.7% where root systems of herbaceous and dwarf-shrub species are concentrated in forest ecosystems. It was established that a considerable content of the radionuclide is retained in the aboveground part of lingonberry phytomass even with low density of radioactive soil contamination. It was found that in 1998, at relatively low value of soil 137Cs contamination density (49±5.6 kBq∙m–2), specific activity of 137Cs in aboveground phytomass of lingonberry was 8043±511 Bq∙kg–1, while in 2021 (value of soil 137Cs contamination density 22±0.3 kBq∙m–2) — 1046±182 Bq∙kg–1. The values of radionuclide transfer coefficients in 1998 were quite significant and varied within wide range: in the air-dry aboveground phytomass from 33.4 to 164.1 m2∙kg–1∙10–3 and in the fresh berries, from 9.5 to 26.0 m2∙kg–1∙10–3. Dependencies between density of radioactive soil contamination and the content of 137Cs in the aboveground part of lingonberry phytomass and berries were calculated, which can be applied in the practice of their harvesting. It was found that lingonberry belongs to the group of plants characterized by the high content of 137Cs in the aboveground vegetative phytomass. Harvesting of lingonberry leaves for the production of medicinal products should be restricted in all areas contaminated with 137Cs. Lingonberry fresh berries can be harvested in areas with a radioactive soil contamination density up to 74 kBq∙m–2.

How Do Nitrogen Deposition, Mowing, and Deer Grazing Drive Vegetation Changes on Dune Heaths?

Heathland vegetation has undergone significant changes in the past century, e.g., due to airborne pollutants and a lack of proper management. Understanding the interactions between these factors in combination is pivotal for heathland conservation. Here, we studied the vegetation changes at a dune heath in a four-year manipulation experiment analysing the combined effects of nitrogen deposition, mowing, and deer grazing. Our results showed no significant effect of nitrogen deposition and deer grazing on plant growth and cover of dwarf shrubs within the experimental plots. However, high loads of nitrogen decreased bryophyte cover and increased the growth and cover of sand sedge Carex arenaria L. Mowing adversely affected the dwarf shrub community, e.g., the dwarf shrub species crowberry Empetrum nigrum L., and facilitated increased cover and plant growth of graminoids. Plant growth and the cover of C. arenaria increased in plots without deer grazing, whereas bryophyte cover decreased significantly without grazing. We do not recommend intensive mowing of vegetation as a conservation method for dune heaths because it promotes graminoids. From a conservation aspect, it is essential to consider the effect of deer on heathlands because they both impede some species and benefit others and mitigate the adverse effects of nitrogen deposition on dune heaths.

Night-time water relations and gas exchange in cut shoots of five boreal dwarf shrub species: impact of soil water availability.

Recent findings suggest that drought may affect plants' daytime and night-time stomatal regulation differently. However, knowledge of night-time stomatal behaviour in dwarf shrubs growing in boreal ecosystems is lacking. We sampled cut shoots from dwarf shrub species to elucidate their capacity to transpire at night and the effect of drought on stomatal regulation. The shoots' water relations and gas exchange were measured under controlled conditions in a growth chamber. The studied species demonstrated considerable differences in their diurnal water use. The night-time water use percentage of daytime water use (NWU) reached up to 90% in Andromeda polifolia and Vaccinium uliginosum. In Rhododendron tomentosum, Vaccinium myrtillus and Chamaedaphne calyculata, the NWU was 62, 27 and 26%, respectively. The shoots of C. calyculata showed a significant increase (P < 0.001) in the transpiration rate (E) during the night. However, in R. tomentosum, a decrease (P < 0.05) in nightly E was observed. The shoot conductance (g) at the end of the night was lower than daytime g in all studied species, but the difference was not significant for V. uliginosum. Across the species, NWU was negatively related (P < 0.001) to the soil volumetric water content (SWC) in the plant habitat. However, daytime E and g were positively related (P < 0.05) to the habitat SWC. Only in V. myrtillus was night-time E higher (P < 0.05) in dry conditions than in wet conditions. Our results demonstrate high variability in diurnal water relations in dwarf shrubs, which can keep stomata open in the dark even when drought limits daytime g and E.

Annual ring width in the arctic-alpine dwarf-shrub species Salix herbacea - Dataset from long-term alpine ecosystem research in central Norway (LTAER-NO)

Here, we present a datapaper containing microscopically measured data of annual ring widths in the arctic-alpine dwarf-shrub species Salix herbacea (central Norway). The dataset will be updated with future measurements.

Close coupling of plant functional types with soil microbial community composition drives soil carbon and nutrient cycling in tundra heath

AimsThis study aimed at elucidating divergent effects of two dominant plant functional types (PFTs) in tundra heath, dwarf shrubs and mosses, on soil microbial processes and soil carbon (C) and nutrient availability, and thereby to enhance our understanding of the complex interactions between PFTs, soil microbes and soil functioning.MethodsSamples of organic soil were collected under three dwarf shrub species (of distinct mycorrhizal association and life form) and three moss species in early and late growing season. We analysed soil C and nutrient pools, extracellular enzyme activities and phospholipid fatty acid profiles, together with a range of plant traits, soil and abiotic site characteristics.ResultsShrub soils were characterised by high microbial biomass C and phosphorus and phosphatase activity, which was linked with a fungal-dominated microbial community, while moss soils were characterised by high soil nitrogen availability, peptidase and peroxidase activity associated with a bacterial-dominated microbial community. The variation in soil microbial community structure was explained by mycorrhizal association, root morphology, litter and soil organic matter quality and soil pH-value. Furthermore, we found that the seasonal variation in microbial biomass and enzyme activities over the growing season, likely driven by plant belowground C allocation, was most pronounced under the tallest shrub Betula nana.ConclusionOur study demonstrates a close coupling of PFTs with soil microbial communities, microbial decomposition processes and soil nutrient availability in tundra heath, which suggests potential strong impacts of global change-induced shifts in plant community composition on carbon and nutrient cycling in high-latitude ecosystems.

Ground Vegetation in Pinus sylvestris Forests at Different Successional Stages following Clear Cuttings: A Case Study.

The impact of intensive forestry on various components of ecosystems has become the main subject of public and scientific debate in many regions in recent years. Forest ground vegetation is considered one of the most consistent and biodiversity-rich indicators of a certain stage of successional forest development. Therefore, changes in this forest component can potentially show the risks of forest damage due to clear-cutting and recovery trends. This study was carried out to identify the ground vegetation species diversity, including species composition and cover, also ground vegetation species relations with organic layer (forest floor) and upper mineral soil parameters at the different successional stages of the Pinus sylvestris L. stand development, including 1–2-year-old clear-cuts, and 6–130 years old stands. This study identified that the herb and dwarf shrub species were more light-demanding in the 2-year-old clear-cuts, as well as in the 6-year and 10-year old P. sylvestris stands compared to the middle-aged and mature forest stands. The dominant ground vegetation species, characteristic for the Pinetum vaccinio-myrtillosum forest type, were negatively dependent on the forest floor mass; they also had negative correlations with the concentrations of total P, K, Ca, and Mg in the forest floor and upper mineral soil but had positive correlations with the soil pH values and total N. The developed regression models of the percentage cover of mosses, herbs and dwarf shrubs according to the P. sylvestris stand age highlight the stabilization of the increase in the moss cover about 30 years after clear-cutting, with no clear trend for vascular species. The herbs and dwarf shrub species were highly variable during the stand rotation due to the species-specific characteristics and random factors rather than due to the influence of stand age. In this study, relatively short-term changes in ground vegetation species composition and percentage cover were determined after clear-cutting, but an important aspect is that new ground vegetation species appeared in the open areas, creating the potential for increasing species diversity. The clear-cutting system supports different species and numbers of herbs and mosses at different stages of stand development, which potentially increases the overall vegetation species diversity of the ecosystem.

Alpine ericaceous dwarf shrubs as summer food resources for Asiatic black bears in Japan

The Asiatic black bear (Ursus thibetanus) is known to use the fruits of various fleshy-fruited plant species as food resources. However, there is no published evidence regarding whether they feed on the berries of 4 ericaceous dwarf shrub species that are widely distributed in alpine regions in Japan (Empetrum nigrum, Vaccinium uliginosum, Gaultheria pyroloides, and Vaccinium vitis-idaea). We assessed the use of, and preference for, these berries by black bears and identified the production and morphological and nutritional characteristics of these berries in the alpine zone of Mt. Asama, central Japan. Using camera-trap survey and scat analyses between July and November in 2017, 2018, and 2019, we obtained the first evidence that these bears consume large quantities of E. nigrum berries in the alpine zones during the summer. The density of berries per square meter was highest for E. nigrum. By contrast, the cost–benefit ratio of morphological fruit attractiveness (i.e., fresh pulp weight and dry pulp weight divided by total fresh seed weight per fruit), crude protein, crude fat, and nitrogen-free extract levels were lowest in E. nigrum berries. Therefore, fruit use by black bears appeared to be influenced by fruit production rather than the morphological or nutritional value of the fruits. Bears may compensate for this nutritional deficit by consuming large quantities of these berries. Consequently, E. nigrum berries are key food items for black bears in Japan and may compensate for summer food shortages.

Review: Phytogeography and history of Japanese beech forests: Recent advances and implications for vegetation ecology

AbstractIn this review, the phytogeography and history of Japanese beech (Fagus crenata Blume and F. japonica Maxim.) forests are re‐examined in light of recent phytogeographical and palaeobotanical research advances. I explain the floristics and the climatic and geological contrasts between Japanese beech forests on the Sea of Japan side and the Pacific side of the Japanese archipelago. We also review recent studies on the origin of dwarf evergreen shrub species occurring along the Sea of Japan. The old scenario that these dwarf evergreen shrub species diverged directly from counterpart species occurring on the Pacific coast of Japan is no longer supported. We propose more intricate speciation processes, including phylogenetic relations to extant Chinese species and inter‐species hybridization. We also review the results of recent palaeobotanical studies of forests on the Japanese islands in the Quaternary. The long persistence of beech forests through glacial/interglacial cycles of the Quaternary—with repeated spread and contraction of the geographical range—is confirmed. In addition, we briefly explain the phytosociological classification system of the Japanese beech forest and the geographical ranges of each vegetation type. We review studies of the geographic distribution of F. crenata and F. japonica at the population level, highlighting the need for further ecological and genetic studies of population dynamics near the range limits to understand historic migration processes better.

Influence of increased nutrient availability on biogenic volatile organic compound (BVOC) emissions and leaf anatomy of subarctic dwarf shrubs under climate warming and increased cloudiness.

Background and AimsClimate change is subjecting subarctic ecosystems to elevated temperature, increased nutrient availability and reduced light availability (due to increasing cloud cover). This may affect subarctic vegetation by altering the emissions of biogenic volatile organic compounds (BVOCs) and leaf anatomy. We investigated the effects of increased nutrient availability on BVOC emissions and leaf anatomy of three subarctic dwarf shrub species, Empetrum hermaphroditum, Cassiope tetragona and Betula nana, and if increased nutrient availability modifies the responses to warming and shading.MethodsMeasurements of BVOCs were performed in situ in long-term field experiments in the Subarctic using a dynamic enclosure system and collection of BVOCs into adsorbent cartridges analysed by gas chromatography–mass spectrometry. Leaf anatomy was studied using light microscopy and scanning electron microscopy.Key ResultsIncreased nutrient availability increased monoterpene emission rates and altered the emission profile of B. nana, and increased sesquiterpene and oxygenated monoterpene emissions of C. tetragona. Increased nutrient availability increased leaf tissue thicknesses of B. nana and C. tetragona, while it caused thinner epidermis and the highest fraction of functional (intact) glandular trichomes for E. hermaphroditum. Increased nutrient availability and warming synergistically increased mesophyll intercellular space of B. nana and glandular trichome density of C. tetragona, while treatments combining increased nutrient availability and shading had an opposite effect in C. tetragona.ConclusionsIncreased nutrient availability may enhance the protection capacity against biotic and abiotic stresses (especially heat and drought) in subarctic shrubs under future warming conditions as opposed to increased cloudiness, which could lead to decreased resistance. The study emphasizes the importance of changes in nutrient availability in the Subarctic, which can interact with climate warming and increased cloudiness effects.

西北干旱区泡泡刺灌丛的降雨再分配特征及影响因素分析

定量分析植被冠层对降雨再分配过程的影响, 是认识陆地生态系统水文循环的重要环节。然而, 由于干旱区天然植被分布稀疏、形态结构特殊, 其降雨再分配过程的测算较为困难, 相关研究较少, 特别是关于荒漠低矮灌丛的降雨再分配研究鲜有报道。本文以河西走廊中段临泽绿洲—荒漠过渡带的天然建群种泡泡刺灌丛(Nitraria sphaerocarpa)为研究对象, 基于3年逐个单次降雨事件的观测数据分析了生长季泡泡刺灌丛的降雨再分配特征及主要影响因素, 量化了泡泡刺灌丛覆盖下实际进入土壤的有效降雨量及其空间分布特征。结果表明：(1)生长季泡泡刺灌丛的平均穿透率、树干茎流率和冠层截留损失率分别为87.89%、1.61%和10.50%；(2)降雨量是影响泡泡刺灌丛降雨再分配特征的关键气象因素, 其与穿透雨量、树干茎流量、冠层截留损失量之间具有显著的统计关系(P < 0.001)；(3)与干旱区其他稀疏植被相比, 泡泡刺灌丛的穿透率和集流率较高, 冠层截留损失率较低, 与其特殊的植被形态特征有关, 相关分析的结果表明, 泡泡刺灌丛的穿透雨量与植被面积指数和株高呈显著的负相关关系(P < 0.001), 树干茎流量与树干倾角呈显著的正相关关系(P < 0.01)。这些研究结果增进了我们对于绿洲—荒漠过渡带植被对局地水文过程影响的认识, 为合理估算干旱区稀疏植被覆盖下的冠层截留损失提供了方法参考。;Analyzing quantitatively the effect of vegetation canopy on rainfall partitioning is an important part for better understanding the hydrological cycle in terrestrial ecosystems, which is particularly useful for hydrologic budget estimation, hydrological models' establishment and afforestation projects' implement in drylands. However, it is difficult to measure and calculate its rainfall partitioning process of the natural vegetation in the drylands due to its sparse distribution and special morphological structure, and very few field measurements have conducted specially for the natural desert dwarf shrub species, which distributed widely in the oasis-desert ectone of northwestern China. Here we present results of the partitioning of rainfall into throughfall (TF), stemflow (SF) and interception loss (IL) by a shrub species Nitraria sphaerocarpa, a naturally dominant species of Linze oasis-desert ecotone in the middle part of the Hexi Corridor, based on the observation data during the growing season for 3 years. Consequently, the effective rainfall that actually enters the soil and its spatial distribution characteristics beneath the N. sphaerocarpa canopy are quantified. We also analyze the influencing factors for rainfall partitioning by N. sphaerocarpa canopy. The results show that: (1) on average, the measured throughfall, stemflow and derived interception loss by N. sphaerocarpa during growing season account for 87.89%, 1.61% and 10.50% of gross rainfall amount, respectively. The average funneling ratio for N. sphaerocarpa is (129.66 ±93.01) and its canopy storage capacity is 0.42 mm. N. sphaerocarpa's throughfall is produced from rainfall events with total amount more than 0.2 mm, while its stemflow does not occur following rainfall events less than 1.5 mm. (2) Rainfall amount is the key meteorological factor affecting the rainfall partitioning characteristics. There are significant correlations between rainfall amount and throughfall, stemflow and interception loss (P < 0.001). Other meteorological variables like canopy surface temperature, atmospheric temperature, atmospheric humidity and vapor pressure can also affect rainfall redistribution process. (3) Compared with other sparse vegetation in drylands, the N. sphaerocarpa has higher throughfall percentage and funneling ratio, but lower interception loss percentage. Special canopy morphology of N. sphaerocarpa may play an important role in its pattern of rainfall partitioning. Pearson correlation analysis shows that throughfall has significantly negative correlation with plant area index (PAI) and shrub height (P < 0.001), and stemflow has positive correlation with stem orientation (P < 0.01). Other canopy morphology like bark roughness, leaf shape and canopy form, which lack of quantitative description, are also vital for rainfall partitioning patterns. The results might improve better understanding of shrubs' role on the local hydrological processes in oasis-desert ecotone, and provide a reasonable method for estimating interception loss by sparse vegetation in drylands.

An Annotated and Updated Checklist of the Hungarian Dendroflora

The checklist includes tree, shrub, dwarf shrub, woody liana and epiphyte species that occur or have occurred in Hungary except the settlements and other intensively utilised objects. 437 dendrotaxa were included and evaluated in this list. This means 281 species, 22 subspecies, 128 nothospecies and 6 nothosubspecies. Based on the indigenat, 260 native, 92 alien and 9 cryptogenic dendrotaxa live in Hungary, furthermore 54 cultivated dendrotaxa and 22 dendrotaxa with questionable occurrence. Analysing the invasive status of alien species, 19 invasive or being in the early stages of invasion, 12 naturalised and 61 casual dendrotaxa can be distinguished. According to residence time status, the number of archaeophytes is 16 and that of neophytes is 76. Of the 260 native dendrotaxa, 9 were extinct or presumably extinct. 44 dendrotaxa are considered to be proven endemic, and there are 8 subendemic. Of the 134 nothotaxa on the list, 14 are artificial and 120 are of natural origin.

Plant\u2013plant interactions and local patterns of diversity from semi-arid to subalpine Mediterranean plant communities

An understanding of the diversity spatial organization in plant communities provides essential information for management and conservation planning. In this study we investigated, using a multi-species approach, how plant–plant interactions determine the local structure and composition of diversity in a set of Mediterranean plant communities, ranging from semi-arid to subalpine habitats. Specifically, we evaluated the spatial pattern of diversity (i.e., diversity aggregation or segregation) in the local neighborhood of perennial plant species using the ISAR (individual species–area relationship) method. We also assessed the local pattern of beta-diversity (i.e., the spatial heterogeneity in species composition among local assemblages), including the contribution of species turnover (i.e., species replacement) and nestedness (i.e., differences in species richness) to the overall local beta-diversity. Our results showed that local diversity segregation decreased in the less productive plant communities. Also, we found that graminoids largely acted as diversity segregators, while forbs showed more diverse neighborhoods than expected in less productive study sites. Interestingly, not all shrub and dwarf shrub species aggregated diversity in their surroundings. Finally, an increase in nestedness was associated with less segregated diversity patterns in the local neighborhood of shrub species, underlining their role in creating diversity islands in less productive environmental conditions. Our results provide further insights into the effect of plant–plant interactions in shaping the structure and composition of diversity in Mediterranean plant communities, and highlight the species and groups of species that management and conservation strategies should focus on in order to prevent a loss of biodiversity.

Dendrometer measurements of arctic-alpine dwarf shrubs and micro-environmental drivers of plant growth - Dataset from long-term alpine ecosystem research in central Norway

Here, we present fine-scale measurements of stem diameter variation from three common arctic-alpine dwarf-shrub species monitored in two mountain regions of Central Norway. All three species (Betula nana, Empetrum nigrum ssp. hermaphroditum, and Phyllodoce caerulea) are abundant within the studied regions and highly important contributors to potential future arctic-alpine vegetation shifts. A profound understanding of their radial growth patterns therefore has the potential to yield crucial information regarding climate-growth relations within these ecosystems. We used high-resolution dendrometers (type DRO) to monitor 120 specimens, taking measurements near the shoot base of one major horizontal stem. Along with the shrub growth measurements, we measured on-site micro-environmental data at each studied site, including shoot zone and root zone temperatures as well as soil moisture. All data were recorded at an hourly scale and are presented as daily mean values. The monitoring period spanned five full years (2015 - 2019), with additional data from 2014 and 2020. Data were collected within one of the most continental climate regions of Europe, the Vågå/Innlandet region, and in the oceanic climate region Geiranger/Møre og Romsdal, spanning a steep climate gradient over just ~100 km horizontal distance. Both study regions are characterized by steep elevational gradients and highly heterogeneous micro-topography. The studied sites were chosen to represent these natural conditions using the transect principle. The collection of our original data is subject of our long-term alpine ecosystem monitoring program since 1991, from which numerous publications function as the basis for a recent project on the use of dendrometer data in alpine ecosystem studies.

Facilitation by a dwarf shrub enhances plant diversity of human-valued species at high elevations in the Himalayas of Nepal

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.

Testing the potential of the dwarf shrub Dryas octopetala L. for dating in dendrogeomorphology

Dendrochronology has been applied around the world over decades to reconstruct historical geomorphological events and climatic conditions. Traditionally, this research has been conducted using trees (conifers as well as broad-leaved trees) but, in the last few decades, several shrub and dwarf shrub species have also been shown to be useful for dendrochronological purposes. This study assesses the potential of mountain avens (Dryas octopetala L.) to provide accurately dated information about past debris-flow events. The study site, the Marlt-Graben debris-fan, is located in South Tyrol (Italy). 119 shrubs from three debris-flow tracks were analyzed. The longest radius of each sample was measured and cross-dated to build two chronologies for each debris-flow track, one for each leveé. Correlations between these chronologies and precipitation and temperature data from five climate stations located in the proximity of the study site were calculated. The cross-dating procedure was complex, but a strict grouping of the samples, based on the specific leveés of the tracks, enabled the construction of mean chronologies for each of the individual slopes. Although the development of a mean chronology for the study area was unsuccessful, the cross-dated ages of the single shrubs allowed us to reconstruct debris-flow events by utilizing the minimum age method. The low climate correlations suggest that micro site conditions strongly influence the growth of this dwarf shrub. Although the results of this study suggest that Dryas octopetala may provide useful dendroecological information, additional information about its growth dynamics is required before this potential can be fully realized.

Different sets of traits explain abundance and distribution patterns of European plants at different spatial scales

AbstractAimPlant functional traits summarize the main variability in plant form and function across taxa and biomes. We assess whether geographic range size, climatic niche size, and local abundance of plants can be predicted by sets of traits (trait syndromes) or are driven by single traits.LocationEurasia.MethodsSpecies distribution maps were extracted from the Chorological Database Halle to derive information on the geographic range size and climatic niche size for 456 herbaceous, dwarf shrub and shrub species. We estimated local species abundances based on 740,113 vegetation plots from the European Vegetation Archive, where abundances were available as plant species cover per plot. We compiled a complete species‐by‐trait matrix of 20 plant functional traits from trait databases (TRY, BiolFlor and CLO‐PLA). The relationships of species’ geographic range size, climatic niche size and local abundance with single traits and trait syndromes were tested with multiple linear regression models.ResultsGenerally, traits were more strongly related to local abundances than to broad‐scale species distribution patterns in geographic and climatic space (range and niche size), but both were better predicted by trait combinations than by single traits. Local abundance increased with leaf area and specific leaf area (SLA). Geographic range size and climatic niche size both increased with SLA. While range size increased with plant height, niche size decreased with leaf carbon content.ConclusionFunctional traits matter for species’ abundance and distribution at both local and broad geographic scale. Local abundances are associated with different combinations of traits as compared to broad‐scale distributions, pointing to filtering by different environmental and ecological factors acting at distinct spatial scales. However, traits related to the leaf economics spectrum were important for species’ abundance and occurrence at both spatial scales. This finding emphasizes the general importance of resource acquisition strategies for the abundance and distribution of herbaceous, dwarf shrub and shrub species.