Abundance Of Plant Communities Research Articles

Spatial dynamics and drivers of recent changes in grass and shrub cover in submontane grassland plant communities

AbstractShrub encroachment into grassland ecosystems has been increasingly observed and documented worldwide in recent years. A grass–shrub transition can affect the diversity, abundance and functional integrity of grassland plant communities and understanding the drivers behind these processes is therefore crucial. While potential environmental drivers are often investigated, the role of spatial patterns of neighbouring shrub density in local shrub encroachment has been less well studied. The aim of this study is to investigate the relative role of neighbouring shrub density and topography as potential key drivers of shrub encroachment in a typical montane grassland ecosystem in New Zealand. We used the SPOT (Satellite Pour l’Observation) 6/7 multispectral imagery captured on one day in 2013 and in 2017 to calculate recent changes in shrub/grass cover during this period. Using the Normalised Difference Vegetation Index (NDVI), we classified the study area into grassland and shrubland and quantified the extent and change in these two land-cover types over the study period. We then investigated the relationships between changes in land cover and neighbourhood shrub density, elevation and aspect. Between 2013 and 2017, there was an overall shrubland increase of + 0.35% of the study area per year, and grassland decrease of −0.43% per year. Locations at which any change in vegetation type occurred were more likely to be at mid-elevation (c. 600–1,000 m a.s.l.) and on west-facing slopes. Highest shrub expansion rates were observed on areas that were on warmer, north-facing slopes and at elevations below 900 m a.s.l.; this is consistent with areas below the pre-human, natural treeline which is estimated to be at very similar elevations. We found a marked threshold in the degree to which neighbourhood shrub density correlated with local shrub encroachment: local shrub encroachment only occurred when shrub cover in the neighbourhood exceeded 40% and peaked at c. 60% indicating the potential for a sudden grass–shrub regime shift once shrub cover reaches a certain level. Our study provides new evidence from the Southern Hemisphere of a measurable and interacting effect of topography and neighbourhood shrub density on recent shrub encroachment rates in montane grasslands even over short time periods.

Ecological Impacts of Introduced European Rabbits (Oryctolagus cuniculus) on Island Ecosystems in the Mediterranean

The Cyclades Islands (Aegean Sea, Greece) are part of the Mediterranean Basin biodiversity hotspot and harbor a plethora of endemic species. Plant communities on the smaller islands in this region have largely evolved in the absence of herbivory and frequently lack antiherbivore defenses. This study evaluates the short- and long-term effects of the European rabbit (Oryctolagus cuniculus), an herbivore that has been released on numerous islands in the region, by comparing islands that 1. have historically been rabbit-free (ungrazed); 2. are currently grazed by rabbits, and 3. have previously been grazed, but are now rabbit-free. Ecological impacts of rabbits on the Aegean Islands were investigated by assessing the abundance, composition, and diversity of plant and arthropod communities as well as soil characteristics. Our results indicate that ungrazed islands have more arthropod species, more specialized or endemic plant species, and less exposed soil than currently grazed islands. While ungrazed islands did not necessarily possess higher total plant species richness, they did harbor significantly more small-island endemic taxa relative to presently grazed islands. This study indicates that native plant communities on Mediterranean islets are not adapted to the presence of this introduced species and that the practice of intentionally releasing rabbits on islands has significant and lasting negative ecological impacts, especially on small islands. While a complete recovery of post-rabbit was not evident over the time span of our research, both arthropod and plant data indicate that partial recovery is possible once rabbits have been removed.

Negative plant-soil feedbacks disproportionally affect dominant plants, facilitating coexistence in plant communities

Plant-soil feedbacks (PSFs) are suggested to be major drivers of plant species coexistence and exotic invasions in natural plant communities, where species with more positive PSFs are thought to be more abundant in communities. Most evidence for this comes from mesocosm experiments with single species, but whether the results are transposable to diverse plant communities is mostly not verified and remains debated. We performed a combined monoculture and community experiment to test whether PSFs in monocultures predict PSFs in communities, and to infer the role of PSFs in invasive plant success. We found that (1) PSFs from monocultures were poor predictors for PSFs in plant communities, (2) competitive strength of invasive species did not consistently depend on PSF, and (3) dominant species experienced a significantly stronger negative PSFs than non-dominant species when grown in community. Hence, PSFs of plant species in monocultures seem less predictive for their abundance in plant communities or for invasibility than previously assumed. Nevertheless, PSF—and particularly negative PSF—seems indeed a major driver of plant species coexistence, with a strong species-specific pathogenic effect on dominant plants facilitating the persistence of rare species.

Сomparative analysis of the species abundance and structure of plant communities involving <i>Rhamnus cathartica</i> in Belarus and in the midwestern regions of the USA

The history of intentional introduction of Rhamnus cathartica L. into the Midwestern regions of the USA is briefly described. The species abundance and structure of plant communities, in which Rhamnus cathartica, a native species for Belarus and invasive in the USA grows, has been studied. We compared the studied parameters (floristic description of the monitoring plots, field enumeration of Rhamnus cathartica individuals, average height, projective coverage of the accompanying herb species) at two permanent sample plots in Belarus and three permanent sample plots in the Midwestern regions of the USA. The data confirmed the hypothesis of increased competitiveness of non-native species in the secondary range (EICA). In American populations, compared to Belarusian populations, Rhamnus cathartica has larger sizes, higher seed production, higher number of juvenile individuals, and higher total number of individuals in the population up to the formation of single-species thickets. Invading Rhamnus cathartica into natural plant communities in the USA reduces the number of herbaceous species 8 times! As control measures, the Minnesota Arboretum has begun balding the areas invaded by Rhamnus cathartica, removing juvenile plants (one to five years old) and replanting native tree species.

Climate and fragment area jointly affect the annual dynamics of seedlings in different functional groups in the Thousand Island Lake.

Habitat fragmentation and climate change are the two main threats to global biodiversity. Understanding their combined impact on plant community regeneration is vital for predicting future forest structure and conserving biodiversity. This study monitored the seed production, seedling recruitment and mortality of woody plants in the Thousand Island Lake, a highly fragmented anthropogenic archipelago, for 5 years. We analyzed the seed-seedling transition, seedling recruitment and mortality of different functional groups in the fragmented forests and conducted correlation analyses involving climatic factors, island area, and plant community abundance. Our results showed that: 1) shade-tolerant and evergreen species had higher seed-seedling transition, seedling recruitment and survival rate than shade-intolerant and deciduous species in time and space, and these advantages increased with the island area. 2) Seedlings in different functional groups responded differently to island area, temperature and precipitation. 3) Increasing active accumulated temperature (the sum of the mean daily temperature above 0 °C) significantly increased seedling recruitment and survival, and warming climate favored the regeneration of evergreen species. 4) The seedling mortality rate of all plant functional groups increased with the increase of island area, but the increasing strength weakened significantly with the increase of the annual maximum temperature. These results suggested that the dynamics of woody plant seedlings varied among functional groups, and can be regulated separately and jointly by fragmentation and climate.

Generating ecological insights from historical data

Generating ecological insights from historical data

Understory plant growth forms respond independently to combined natural and anthropogenic disturbances

Natural disturbances can maintain forest diversity by creating a heterogeneous resource landscape, which can contribute to coexistence of early- and late-successional species. However, almost all forested ecosystems are also subject to multiple anthropogenic stressors, which could inhibit plant diversity and forest recovery after natural disturbances. Here, we present the first large-scale replicated field experiment testing the interactions among two natural and two anthropogenic disturbances in a mature secondary temperate forest. Specifically, we test the extent to which: 1. a natural windthrow (tornado), 2. deer browsing, 3. salvage logging, a common forestry practice to generate revenue after natural disturbances, and 4. mechanical removal of the understory, drive subsequent plant community assembly, diversity, and abundance. Our results have two clear messages. First, the combined disturbances, especially salvage logging, increased plant species richness and abundance; we found 65 more species in 0.1 ha of the disturbed areas versus the same area of reference forest. Second, we found that it was critical to analyze plant growth forms separately; each major plant growth form responded to the disturbances differently. Surprisingly, salvage logging, browsing, and vegetation removal had negligible effects on the diversity and abundance of tree seedlings or saplings. In contrast, salvaging increased herb richness by 30% (six extra species per 36 m2 plot), and shrubs were twice as abundant in salvaged versus unsalvaged plots. The combined disturbances created unique plant communities in comparison to adjacent undisturbed reference sites, but plant growth forms differed in which combination of disturbances shifted community composition the most. We did not find that non-native invasive species substantially increased in abundance in response to the disturbances, nor were invasive species unique to the salvaged areas. Together, our results demonstrate that a patchwork of combined natural and anthropogenic disturbances can promote plant diversity in a human-modified temperate forest. In particular, the combination of a natural wind disturbance and salvage logging benefited native herbaceous species, the plant group that represents the vast majority of vascular plant species (∼80%) in temperate forests across the world.

Effects of grazing on underground parts of marsh plants by wintering Middendorf's bean goose Anser fabalis middendorffii: Its role as a keystone species in plant communities

AbstractGeese are known to impact on the species composition and abundance of plant communities, with grazing pressure by flocks negatively affecting various aspects of vegetation and ecosystems. However, positive effects have also been highlighted, including grazing preventing competition among plants and helping to maintain a high level of biodiversity. The Middendorf's bean goose Anser fabalis middendorffii is one waterfowl that winters in the marsh lands of Japan. At the Katano‐kamoike pond, the species main wintering site in central Japan, the effects of goose grazing on the structure of marsh plant communities were investigated by using field observations and experiments. During observations of foraging behavior, A. fabalis middendorffii mainly foraged on underground parts of Zizania latifolia and Bolboschoenus fluviatilis, including rhizomes, roots, and tubers, at the marshlands of the pond. The field census showed the biomass of the underground parts was significantly reduced by A. fabalis middendorffii grazing during winter. Specifically, the biomass of rhizomes in Z. latifolia was drastically decreased. Data collected from exclosure experiments over 5 years suggested that grazing pressure regulated the overgrowth of B. fluviatilis and enhanced the abundance of Z. latifolia. Furthermore, a field census of marsh plants at the Shimofukuda reservoir, where there have been no A. fabalis middendorffii, confirmed that the absence of A. fabalis middendorffii was related to a decrease in the abundance and biodiversity of marsh plants. In the Katano‐kamoike pond, A. fabalis middendorffii may play a key role in maintaining plant diversity.

The results of the field accounting of medicinal plants in the forest and forest-steppe zones of Central Russia

To assess the potential of the raw material base of medicinal plants and search for new plant sources of biologically active substances, it is necessary to monitor and record the biological diversity of plants, their number and abundance in natural plant communities. Plants are counted by the transect method. In the course of field research in 2022, the biodiversity, abundance, and abundance of medicinal plants in three regions of Central Russia were assessed. In the Lipetsk Region (the lower reaches of the Chichera River, the valley of the Sukhaya Lubna River), the most notable species of the Ranunculaceae families were identified: Adonis vernalis L. (spring adonis); Rosaceae: Agrimonia eupatoria L. (common agrimony); Filipendula vulgaris Moench (six-petalled meadowsweet). In the Samara region (floodplain of the Sok River) - Rosaceae: Sanguisorba officinalis L. (burnet officinalis); Filipendula vulgaris Moench; Ranunculaceae: Adonis vernalis L. In the Moscow, Ryazan region (Meshchera) species of families - Rosaceae: Potentilla argentea L. (silver cinquefoil) (Rosaceae), Fragaria vesca L. (wild strawberry), Potentilla erecta L. (upright cinquefoil), Comarum palustre L. (marsh cinquefoil); Onagraceae: Chamaenerion angustifolium (L.) Scop. (fireweed narrow-leaved); Asteraceae: Helichrysum arenarium (L.) Moench.; Caprifoliaceae: Valeriana officinalis L. (valerian officinalis); Hypericaceae: Hypericum maculatum L. (St. John’s wort); Equisetaceae: Equisetum arvense L. (horsetail); Lamiaceae: Stachys palustris L. (marsh weed); Primulaceae: Lysimachia vulgaris L. (common loosestrife). A total of 65 species of medicinal plants have been identified. Species with a noticeable abundance are characterized as a source of a certain group of chemical compounds. To assess the potential of the raw material base of medicinal plants and to search for new plant sources of biologically active substances, it is necessary to monitor and account for the biological diversity of plants, their size and abundance in natural plant communities. Accounting of plants is carried out by the transect method. In the course of field research 2022 year, the biodiversity, size and abundance of medicinal plants in three regions of Central Russia were evaluated. In the Lipetsk region (the lower reaches of the Chicher River, the valley of the Sukhaya Lubna River), the most notable species were identified - Ranunculaceae: Adonis vernalis L.; Rosaceae: Agrimonia eupatoria L.; Filipendula vulgaris Moench. In the Samara region (floodplain of the Sok river) - Rosaceae: Sanguisorba officinalis L.; Filipendula vulgaris Moench; Ranunculaceae: Adonis vernalis L. In the Moscow, Ryazan regions (Meschera) - Rosaceae: Potentilla argentea L., Fragaria vesca L., Potentilla erecta L., Comarum palustre L.; Onagraceae: Chamaenerion angustifolium (L.) Scop.; Asteraceae: Helichrysum arenarium (L.) Moench.; Caprifoliaceae: Valeriana officinalis L.; Hypericaceae: Hypericum maculatum L.; Equisetaceae: Equisetum arvense L.; Lamiaceae: Stachys palustris L.; Primulaceae: Lysimachia vulgaris L. A total of 65 species of medicinal plants have been identified. Species with a noticeable number are characterized as a source of a certain group of chemical compounds.

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EcologyVolume 103, Issue 12 e3409 COVER IMAGEFree Access Cover Image First published: 01 December 2022 https://doi.org/10.1002/ecy.3409AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract COVER PHOTO: Castilleja chromosa as seen in the Golden Gate Range, Nevada, USA. Hemiparasitic plants like C. chromosa parasitize other plants to gain key resources and can reduce host plant abundance. In their study published in this issue (Article e3837; doi: 10.1002/ecy.3837), Hodžić et al. show a positive correlation between hemiparasitic abundance and community evenness in plant communities across North America. Photo credit: Jasna Hodžić. Volume103, Issue12December 2022e3409 RelatedInformation

Long-Term Changes in Abundance and Composition of Forest-Floor Small Mammal Communities in a Landscape with Cumulative Clearcutting

Responses of forest-floor small mammals to clearcutting are species-specific with generalists occupying a range of habitats, and specialists persisting on clearcuts for variable periods. We investigated the responses in abundance and species composition of small mammal communities to cumulative clearcutting of coniferous forests on a landscape that had four independent clearcutting events (Periods 1 to 4) over a 42-year interval from 1979 to 2020 in south-central British Columbia, Canada. We ask if the small mammal communities have changed significantly over these decades owing to removal of old-growth forest by clearcut harvesting. Hypotheses (H) predicted that the small mammal community would (H1) increase in abundance, species richness, and diversity on new clearcuts owing to the availability of early seral post-harvest habitats from cumulative clearcutting; and (H2) have higher mean abundance, species richness, and species diversity in clearcut than uncut forest sites, owing to availability of vegetative food and cover. A third hypothesis (H3) predicted that abundance of (i) early seral vegetation (herbs and shrubs) and (ii) small mammal populations, will be greater in ungrazed clearcut sites than in those grazed by cattle (Bos taurus). Mean total numbers of small mammals on new clearcuts declined in Periods 3 and 4, and hence did not support the abundance part of H1. Much of this decline was owing to low numbers of the long-tailed vole (Microtus longicaudus) and meadow vole (M. pennsylvanicus). Two generalist species: the deer mouse (Peromyscus maniculatus) and northwestern chipmunk (Neotamias amoenus), contributed to high mean species richness and diversity in Periods 2 and 3 before these metrics declined in Period 4, and hence partly supported H1. The similarity in mean total numbers of small mammals in Periods 2 to 4 did not support the abundance prediction of H2 that total numbers would be higher in clearcut than uncut forest sites. Higher mean species richness (Periods 2 and 3) and diversity (Period 3) measurements on clearcut than forest sites, particularly in the early post-harvest years, did support these parts of H2. The vegetation part (i) of H3 was not supported for herbaceous plants but it was for shrubs. The small mammal part (ii) of H3 that populations would be higher in ungrazed than grazed clearcut sites was supported for abundance but not for species richness or diversity. The decline and near disappearance of both species of Microtus was possibly related to the reduction in plant community abundance and structure from grazing (at least for shrubs) and potentially from drought effects associated with climate change. Loss of microtines from these early seral ecosystems may have profound negative effects on various ecological functions and predator communities.

Differential effects of wildfire on salt marsh and coastal forest plant community abundance and diversity in the urbanized Long Island Sound

Coastal marshes are dynamic ecosystems that provide essential ecosystem services and are impacted by a variety of natural and anthropogenic disturbances including flooding, fire, climate change, and urbanization. Coastal saltmarshes are sometimes managed through prescribed burning to enhance habitat value for wildlife and increase plant diversity, but this practice is uncommon in urbanized environments and the effects are unclear. In this study, we observed the effects of a 2017 wildfire on a Spartina saltmarsh and oak-hickory coastal forest over three years on Long Island Sound, New York. The objectives were to determine the impact of the fire on plant abundance, diversity, and invasive species. We studied the marshland and nearby coastal forest. It was concluded that the marsh habitat was more resilient than the forested habitat as its plant composition, abundance and diversity returned to that of the unburned marsh two years post fire. The wildfire caused large shifts in community composition, increasing abundance and diversity in the burned forest relative to the unburned forest, but it also facilitated an increase in non-native species. Because these systems provide countless ecosystem services, further research on the effect of wildfire and interactions with other disturbances is needed.

Effects of simulated precipitation changes on plant community characteristics of wetland in the Yellow River Delta, China

Under the changing climate scenario, changes in precipitation regimes are expected to alter soil water and salinity conditions, with consequences on the characteristics of plant community in estuarine wetland. Here, we used a six-year (2015-2020) precipitation manipulation experiment to examine how plant community characteristics responded to precipitation changes in the Yellow River Delta. The results showed that soil electrical conductivity significantly decreased, while soil moisture significantly increased with increasing precipitation. Precipitation changes altered plant community composition. Increased precipitation reduced the absolute dominance of Suaeda glauca and Suaeda salsa, but increased that of Triarrhena sacchariflora and Imperata cylindrica. Shannon index and Margalef richness index of plant community significantly increased with increasing precipitation. Compared with the control, both decreased and increased precipitation decreased the plant community abundance, frequency and coverage. The treatment of 60% increased precipitation significantly decreased plant community frequency by 54.9%, while the 60% decreased precipitation, 40% decreased precipitation, 40% increased precipitation and 60% increased precipitation treatment significantly decreased plant abundance by 38.9%, 33.8%, 35.8% and 45.7%, respectively. The aboveground biomass significantly increased with increasing precipitation, but aboveground plant biomass under 60% increased precipitation treatment being lower than that reducing under 40% increased precipitation treatment, probably due to the negative effects of flooding stress. In addition, Margalef richness index had a significantly positive relationship with aboveground biomass. Aboveground biomass, Shannon diversity index, Margalef richness index, and Simpson diversity index were negatively related to soil electrical conductivity, and aboveground plant biomass was positively related to soil moisture. Our results revealed that precipitation changes regulate growth characteristics, species composition, and diversity of plant community by altering soil water and salinity conditions in a coastal wetland.

Soil resource availability is much more important than soil resource heterogeneity in determining the species diversity and abundance of karst plant communities.

Resource availability and heterogeneity are recognized as two essential environmental aspects to determine species diversity and community abundance. However, how soil resource availability and heterogeneity determine species diversity and community abundance in highly heterogeneous and most fragile karst landscapes is largely unknown. We examined the effects of soil resource availability and heterogeneity on plant community composition and quantified their relative contribution by variation partitioning. Then, a structural equation model (SEM) was used to further disentangle the multiple direct and indirect effects of soil resource availability on plant community composition. Species diversity was significantly influenced by the soil resource availability in shrubland and woodland but not by the heterogeneity in woodland. Abundance was significantly affected by both soil resource availability and heterogeneity, whereas variation partitioning results showed that soil resource availability explained the majority of the variance in abundance, and the contribution of soil resource heterogeneity was marginal. These results indicated that soil resource availability plays a more important role in determining karst plant community composition than soil resource heterogeneity. Our SEMs further found that the multiple direct and indirect processes of soil resource availability in determining karst species diversity and abundance were different in different vegetation types. Soil resource availability and heterogeneity both played a certain role in determining karst plant community composition, while the importance of soil resource availability far exceeded soil resource heterogeneity. We propose that steering community restoration and reconstruction should be highly dependent on soil resource availability, and multiple direct and indirect pathways of soil resource availability for structuring karst plant communities need to be taken into account.

Danish wetlands remained poor with plant species 17-years after restoration

For more than two decades, wetland restoration has been successfully applied in Denmark as a tool to protect watercourses from elevated nutrient inputs from agriculture, but little is known about how the flora and fauna respond to restoration. The main objective of this study was therefore to: (1) examine plant community characteristics in 10 wetland sites in the River Odense Kratholm catchment, restored between 2001 and 2011 by re-meandering the stream and disconnecting the tile drains, and (2) explore whether the effects of restoration on plant community characteristics change with the age of the restoration. Specifically, we hypothesised that plant community composition, species richness and diversity would improve with the age of the restoration and eventually approach the state of natural wetland vegetation. We found that the prevailing plant communities could be characterised as humid grasslands, moist fallow fields and improved grasslands, whereas the abundance of natural wetland plant communities (e.g., rich fens, fen-sedge beds and humid grasslands) was lower in both the recently restored as well as in older restored wetlands. Additionally, species richness and diversity did not seem to improve with the age of the restoration. We suggest that the continued high nutrient input at the restored sites in combination with restricted dispersal of wetland plant species may hamper the recovery of natural plant communities and that the sites therefore may stay botanically poor for many decades.

Effects of plant species diversity on nematode community composition and diversity in a long-term biodiversity experiment

Diversity loss has been shown to change the soil community; however, little is known about long-term consequences and underlying mechanisms. Here, we investigated how nematode communities are affected by plant species richness and whether this is driven by resource quantity or quality in 15-year-old plant communities of a long-term grassland biodiversity experiment. We extracted nematodes from 93 experimental plots differing in plant species richness, and measured above- and belowground plant biomass production and soil organic carbon concentrations (Corg) as proxies for resource quantity, as well as C/Nleaf ratio and specific root length (SRL) as proxies for resource quality. We found that nematode community composition and diversity significantly differed among plant species richness levels. This was mostly due to positive plant diversity effects on the abundance and genus richness of bacterial-feeding, omnivorous, and predatory nematodes, which benefited from higher shoot mass and soil Corg in species-rich plant communities, suggesting control via resource quantity. In contrast, plant-feeding nematodes were negatively influenced by shoot mass, probably due to higher top–down control by predators, and were positively related to SRL and C/Nleaf, indicating control via resource quality. The decrease of the grazing pressure ratio (plant feeders per root mass) with plant species richness indicated a higher accumulation of plant-feeding nematodes in species-poor plant communities. Our results, therefore, support the hypothesis that soil-borne pathogens accumulate in low-diversity communities over time, while soil mutualists (bacterial-feeding, omnivorous, predatory nematodes) increase in abundance and richness in high-diversity plant communities, which may contribute to the widely-observed positive plant diversity–productivity relationship.

Community‐level responses to increasing dryness vary with plant growth form across an extensive aridity gradient

AbstractAimPerennial plant communities are crucial for regulating ecological processes and maintaining ecosystem functions. Variation in community structure is driven by both biotic and abiotic factors, reflecting adaptation strategies of plant communities to various environments. Although much is known about the response of individual perennial plants to drier climates, empirical evidence of the community‐level responses to increasing dryness is limited.LocationEastern Australia; 1500 km gradient.TaxonPerennial plants.MethodsWe measured the abundance and size distribution (median, skewness and variance) of perennial plant communities from different growth forms (trees, shrubs and grasses), the spatial arrangement of trees in the overstorey and both biotic (competition) and abiotic (climate, soil properties) factors at 150 sites along an extensive aridity gradient from humid to arid areas. We used regression analyses and linear models to explore variation in community structure with increasing aridity and key driving factors for different perennial plant communities.ResultsVariation in community structure differed with growth form. As aridity increased, trees had wider canopies and were spatially aggregated, shrubs became miniaturised, but highly variable in size, and grasses comprised more larger individuals. Biotic and abiotic factors exerted different effects on different growth forms, with trees and shrubs consistently affected by competition and aridity, respectively, whereas grasses were weakly affected by aridity, summer rainfall and soil texture.Main conclusionsOur study highlights the idiosyncratic adaptation strategies used by trees, shrubs and grasses in response to drying climates at the community level through their effect on the size distribution or spatial aggregation. The structure of different perennial growth forms was influenced by different effects from either biotic (competition) or abiotic (climate, soil) factors. Under forecasted drier climates, canopy expansion and greater aggregation of trees might enhance resource sinks and shelter for diverse biota, potentially shielding plant communities against predicted aridification.

MsGBS: A new high-throughput approach to quantify the relative species abundance in root samples of multispecies plant communities.

Plant interactions are as important belowground as aboveground. Belowground plant interactions are however inherently difficult to quantify, as roots of different species are difficult to disentangle. Although for a couple of decades molecular techniques have been successfully applied to quantify root abundance, root identification and quantification in multispecies plant communities remains particularly challenging. Here we present a novel methodology, multispecies genotyping by sequencing (msGBS), as a next step to tackle this challenge. First, a multispecies meta‐reference database containing thousands of gDNA clusters per species is created from GBS derived High Throughput Sequencing (HTS) reads. Second, GBS derived HTS reads from multispecies root samples are mapped to this meta‐reference which, after a filter procedure to increase the taxonomic resolution, allows the parallel quantification of multiple species. The msGBS signal of 111 mock‐mixture root samples, with up to 8 plant species per sample, was used to calculate the within‐species abundance. Optional subsequent calibration yielded the across‐species abundance. The within‐ and across‐species abundances highly correlated (R 2 range 0.72–0.94 and 0.85–0.98, respectively) to the biomass‐based species abundance. Compared to a qPCR based method which was previously used to analyse the same set of samples, msGBS provided similar results. Additional data on 11 congener species groups within 105 natural field root samples showed high taxonomic resolution of the method. msGBS is highly scalable in terms of sensitivity and species numbers within samples, which is a major advantage compared to the qPCR method and advances our tools to reveal hidden belowground interactions.

Contribution of species abundance and frequency to aboveground forest biomass along an Andean elevation gradient

AimsTo determine whether species that contribute most to a plot’s biomass are the most abundant (high local abundance at plot scale) or the most frequent (occur the most across plots at landscape scale), or both. In the tropical Andes, these patterns may change with elevation. This study assesses the contribution to plot’s above-ground biomass (AGB) of the plant community abundance pattern –the prevalence of within-plot dominant species– and the over-occurrence of regionally frequent species, in an elevation gradient. MethodsWe considered all trees ≥2.5 cm DBH from 446 0.1 ha plots in an Amazonia-Andes 260–4350 m elevation cline in N Bolivia. Plot AGB was calculated as the sum of AGBs for all stems contained. We grouped plots into four bins segregated by elevation and ran a bootstrap analysis over subsets of 58 random plots per bin with 100 iterations. Simpson evenness index (ED) for all species in each plot was used as a measure for its species abundance. Values for each plot’s species frequency was calculated as the mean of all species’ in the plot mean frequencies across the bin (i.e. the fraction of plots where each species occurs). We used linear models to correlate plot AGB with (1) elevation and mean annual precipitation (MAP), and (2) ED, plot species frequency and elevation. We performed all analyses at the species, genus and family levels. ResultsPlot AGB was related negatively with elevation, and thus positively with MAP, and also negatively with plot ED and plot species frequency, all significant. Plot species abundance therefore contributes positively to explain the relationship with AGB along elevational gradients, while plot species frequency does so negatively (i.e. less frequent species contribute more to a plot’s AGB across elevation). AGB, for both generic and familial levels was also significantly and negatively correlated with ED, but not related with plot species frequency biomass at these taxonomic levels. ConclusionsPlot AGB was mainly associated with elevation and floristic composition where species, genera and families tended to be abundant at the local (plot) scale. Species that were less frequent at the regional scale contributed with more AGB regionally, while frequency at generic and familial scales did little to explain AGB patterns. This association seems stronger at lower elevations for all taxonomic levels while decreases toward higher elevation. Our study reveals a relationship between plot structural features like C stocks –influenced by species local abundances– and the distribution of taxa across the landscape.

Community Classification of Piñon-Juniper Vegetation in the Four Corners Region, USA

AbstractPiñon-juniper is one of the most common vegetation types in the Four Corners states of the western United States (Arizona, Colorado, New Mexico, and Utah). Because of its high degree of community heterogeneity across the landscape, development of a more detailed and statistically supported classification system for piñon-juniper has been requested by regional land managers. We used a USDA Forest Service Forest Inventory and Analysis (FIA) data set from the Four Corners states to develop a statistics-based classification system for piñon-juniper vegetation. Cluster analysis was used to group piñon-juniper FIA data into community classes. Classification and regression tree analysis was then used to develop a model for predicting piñon-juniper community types. To determine which variables contributed most to classifying piñon-juniper FIA data, a random forest analysis was conducted. Results from these analyses support a six-class piñon-juniper community-type model within the Four Corners states. Using the classification tree, membership of FIA piñon-juniper communities can be accurately predicted (r2 = 0.81) using only relative overstory species abundance. Our dominance-based classification system was useful in classifying piñon-juniper community types and could be used in the field to identify broad community types and complement more refined tools available for stand-scale decisionmaking.Study Implications: Piñon-juniper vegetation communities commonly occur in the Four Corners region of the United States. We used a regional data set to develop a statistically based classification system for piñon-juniper communities. We found support for a dominance-based approach supporting initial classification into six community classes. Classes were based on different overstory species dominance patterns, stand structural characteristics (stand density index, basal area [square meters per hectare], trees per hectare, and stand age), and precipitation patterns (mean annual precipitation and monsoonal index) (Table S2). Community type can be predicted using relative overstory abundance to help managers prioritize regional areas (~6,000 acres [2,428 hectares]) for management and predict responses based on precipitation patterns, current understory tree regeneration, and plant community abundance. This system could lead to better planning documents and management decisions on a regional scale to complement more refined tools available for stand-scale management such as plant associations and detailed soil maps.