Shrub Communities Research Articles

Recovering from quinoa: regenerative agricultural research in Bolivia

ABSTRACT Our objective was to research ways to introduce regenerative agriculture into the fragile landscape of the Southern Altiplano of Bolivia. The quinoa (Chenopodium quinoa) boom (2010–2014) had stimulated farmers to clear large areas of native vegetation: a climax community of shrubs, grasses and cacti. Most fields were soon abandoned, and native plants did not grow back spontaneously. Wind was rapidly eroding the sandy soils. Botanical exploration, informed by local knowledge, discovered species and ecotypes of wild plants, especially shrubs, legumes, grasses and cacti that could be grown as intercrops and as live barriers to control erosion. These plants were evaluated in farmers’ fields, using participatory research. New varieties of quinoa were developed by conventional plant breeding. Researchers learned to grow wild shrubs and grasses in live barriers, to control soil erosion. Wild, native lupines were cultivated for the first time, to use as cover crops. Native cacti were grown in nurseries to encourage farmers to plant them near fields. The new quinoa varieties were better adapted to the local environment. We conclude that this innovative, broad-spectrum research agenda is a kind of plant breeding at the level of the whole landscape. These multiple lines of research are important for developing a diverse, integrated, regenerative agriculture.

Effects of Shrub Encroachment in the Inner Mongolia Ecotones between Forest and Grassland on the Species Diversity and Interspecific Associations

Shrub encroachment, which is the increase in shrubs or woody plants in grassland, is one of the important ecological problems facing grassland worldwide. The study was conducted in the ecotones between the forest and grassland of Inner Mongolia. Using a simple random sampling method, 40 shrubland sample plots, evenly distributed in the typical forest-grass transition area, were selected for community investigation. According to the steppe shrub encroachment index, the grassland was divided into different levels. The species diversity and interspecific association of different levels of sample plots were statistically analyzed and compared. It was found that the Shannon-Wiener index (H) and Simpson index (P) were negatively associated with the shrub encroachment index (p < 0.01) and gradually decreased with increasing levels of shrub encroachment. When the grassland transitioned to severe shrub formation, the species diversity of the community significantly decreased, and H and P were significantly lower than those of the mild and moderate shrub-steppe, and the lowest values were 1.37 and 0.48, respectively. With the increase in the shrub encroachment index, biomass showed a trend of first increasing and then decreasing. The aboveground biomass of shrub interspace and total aboveground biomass in the severe shrub encroachment steppe were significantly lower than those in the mildly and moderately shrub-steppe, with the lowest values of 101.86 g/m2 and 189.69 g/m2, respectively. Shrub encroachment led to a change in the overall association of shrub communities in the ecotones between the forest and grassland of Inner Mongolia from positive to negative. The vast majority of species pairs in the shrub community showed no significant association, and the interspecies association was relatively weak. The results showed that shrub encroachment would affect community species diversity; mild and moderate shrub encroachment had no significant impact on community species diversity, but severe shrub encroachment significantly reduced the community species diversity. There was no significant effect of shrub encroachment on aboveground biomass, which increased first and then decreased, and the herbaceous plant population played a leading role in grassland productivity. The interspecific association of grassland is loose and weak. The community was in the early stage of unstable succession, and it was possible to continue shrub encroachment or reverse succession into a typical grassland in response to the interference of human or environmental factors.

Drivers of Bird and Rodent Assemblage Composition in Rangelands of Southern Mexican Plateau

Rangelands provide ecosystem services for livestock and habitat for many wildlife species. However, the key features that determine their value for biodiversity conservation need to be assessed regionally. To elucidate the structural attributes that drive bird and rodent assemblages in semiarid rangelands in the southern Mexican Plateau, we studied patches of rangelands dominated by herbaceous plants (open) and xerophytic shrub communities (closed). We hypothesized that different guilds and species of birds and rodents are influenced differently by rangeland condition and different habitat components, and that bird assemblages had a higher turnover rate between patches than rodents. We surveyed the birds and rodents during the three regional climatic seasons and measured ground plant cover of herbs, shrubs, nopales, and trees. Through an information-theoretic approach we tested the effect of range condition and season on all variables of habitat and bird and rodent species richness and abundance. Habitat components (shrubs and nopales) most often included in the best/most parsimonious models explained bird and rodent abundances. Rodent species turnover is lower among rangeland plots of the same type geographically separated than between nearby plots of different type. In contrast, bird species turnover was higher because their higher mobility allows them to explore landscape patches than might offer complementation and/or supplementation. Rangelands in the southern Mexican Plateau should be viewed not only as livestock-producing areas but also as landscape components that can and should be used to effectively support biodiversity conservation, complementing the conservation role of other regional habitats. The high biodiversity conservation potential of the rangelands we studied should be recognized, and both habitat conditions should be incorporated in any regional conservation plans.

How can UAV bridge the gap between ground and satellite observations for quantifying the biomass of desert shrub community?

Accurate estimation of the shrub above-ground biomass (AGB) is an essential basis for determining carbon storage and monitoring desertification risk in arid ecosystems. However, significant uncertainties and biases exist in large-scale monitoring of desert AGB due to the scale mismatch and spatio-temporal topological errors between the coarse resolution of satellite images and the limited area that can be surveyed via ground measurements. The rapid development of unmanned aerial vehicle (UAV) technology has the prospective advantage of multi-scale vegetation observation. However, its potential to bridge the gap between satellites and the ground in desert AGB estimation has not yet been explored. This study developed a procedure to fill the gap between satellite and ground measurements based on low-cost and easy-to-use UAV visible-light technology in typical desert shrub communities in Inner Mongolia, China. First, canopy area (CA), canopy maximum height (CH), and canopy volume (CV) metrics derived from UAV-RGB (Red, Green, Blue) images, coupled with structure-from-motion photogrammetry, were used to invert the UAV-based AGB. Then, the UAV-based AGB data were aggregated to different scales to align with satellite data. Here, we focused on examining the performance of generalized additive models between the upscaled UAV-based AGB and vegetation indices (VIs) generated from PlanetScope (resolution: 3 m), Sentinel-2A MSI (resolution: 10 m, 20 m), and Landsat 8 OLI (resolution: 30 m). Finally, we investigated the effects of scale and spectra in the upscaling and modeling process. Results showed that the UAV-based AGB linear prediction models developed by the CV metric performed best for Reaumuria soongarica (R2 = 0.749, RMSE = 65.5 g) and Salsola passerina (R2 = 0.919, RMSE = 56.7 g), which allowed for accurately mapping the desert AGB at the individual plant level with ultra-high resolution (2 cm). The performance of satellite biomass models was excellent based on the upscaled UAV-based AGB and VIs (best-performing models for different satellites: adjusted R2 = 0.625–0.934, RMSE = 35.1–119.1 g/m2). As the resolution of satellite data increases, the increase in variance is a big scale-related challenge in AGB model performance evaluation. It is worth noting that the UAV-based AGB data are unmodifiable due to their area-independent nature, which can avoid the scale-related effect. Moreover, the satellite VIs most closely related to the desert AGB were associated with Red, NIR, and Red-Edge bands. Specifically, we recommend the Red-Edge band when using Sentinel-2A data. This study proves that UAV technology can not only provide exhaustive information on vegetation biomass but also can train and validate satellite data beyond individual UAV observations, which can significantly improve large-scale biomass monitoring if widely applied in the future.

Soil organic carbon stock capacity in karst dolines under different land uses

The soil organic carbon (SOC) was determined in soils of enclosed karst depressions (dolines) (NW Dinaric Mts.) to define their potential for organic carbon sequestration. SOC was measured in the forest, succession (scrubland), and grassland plots at the bottom of dolines at four depths (0–40 cm) and for 40 cm soil layer SOC stock was calculated. We demonstrated that the prevailing fine soil fractions, the C/N ratio and soil thickness play a positive role in the storage capacity of SOC in dolines regardless land use type. Grasslands have the lowest SOC storage capacity (106 t/ha/40 cm), while the highest SOC storage capacity is in succession plots (130 t/ha/40 cm). The last are covered by shrub communities dominated by Prunus spinosa, forming dense communities, and are typical of abandoned croplands or meadows that have been impacted by high levels of nutrients during cultivation phase. At this stage, there is no additional nutrient input in studied plots, which lowers the nutrient content and increases the C/N ratio. C/N ratio is the highest in the forest, where SOC stock capacity is 116 t/ha/40 cm. Given the trend towards the abandonment of agricultural land at Kras Plateau (SW Slovenia), we can expect more overgrowth of dolines, and thus an increase in carbon stocks and stabilization of organic carbon in forest soils. In contrary, we noticed the alarming decrease in grasslands and increase in urban land. The SOC storage in 2020 was for 12,538 t/ha/40 cm lower than in 2002. Although grasslands showed the lowest SOC storage, their contribution to total SOC storage in dolines is very important. Since there is a lack of studies on carbon stocks in doline soils, our research is of great importance and a novelty and gives an important background for further research on SOC stock in karst landscapes worldwide.

Contrasting seasonal abiotic stress and herbivory incidence in Cistus albidus L. plants growing in their natural habitat on a Mediterranean mountain

Mediterranean climate mountain areas are characterized by stressful abiotic conditions for plants. Drought, high photosynthetically active photon flux density and extreme temperatures are the main abiotic factors that drive shrub biodiversity in these areas. However, little is known of the extent to which herbivory may additionally influence the physiology of these shrub communities. We studied the incidence of abiotic and biotic stresses in a representative Mediterranean shrub, Cistus albidus L., growing under natural conditions, with an emphasis on the seasonal occurrence of abiotic stress and herbivory, and the possible influence of mountain aspect and plant ageing on the stress response. Reductions in maximum quantum yield of photosystem II (PSII) occurred during early summer and coincided with a combination of drought, high light and high temperatures (above 35 °C in July). East-facing plants experienced greater reductions in PSII quantum yield during July and leaf water content during September than west-facing ones. However, east-facing plants also showed less herbivory-related damage during winter than west-facing plants, particularly from goats. Plant age did not influence herbivory pressure or the stress response to abiotic factors. It is concluded that C. albidus is a highly tolerant shrub to both abiotic and biotic stress factors in Mediterranean mountain areas. It only shows slight photoinhibition during early summer and mild symptoms of herbivory attack in winter.

Effect of Nitrogen Application on the Sensitivity of Desert Shrub Community Productivity to Precipitation in Central Asia.

Precipitation variability and nitrogen (N) deposition caused by anthropogenic activities could profoundly impact ecosystem productivity and carbon cycling. In desert ecosystems, vegetation is sensitive to changes in precipitation and N deposition. However, the impacts of large changes in precipitation, especially with a concurrent increase in N content, on plant community remain unclear. In this study, we carried out experiments to monitor the impacts of five precipitation levels and two N levels on the plant community function and composition from the Junggar desert in Central Asia during the period 2018–2019. Our results showed that: (1) Aboveground net primary production (ANPP) significantly increased with increasing precipitation, it followed a positive linear model under normal precipitation range, and nonlinear mode under extreme precipitation events; (2) N application led to an increase in ANPP, but did not significantly improve the sensitivity of ANPP to precipitation change; (3) Changes in N content and precipitation, and their impacts on ANPP were mainly driven by plant density. These results provide a theoretical basis for predict the future dynamics of terrestrial vegetation more accurately under climate change and increasing nitrogen deposition.

Patterns and Driving Factors of Diversity in the Shrub Community in Central and Southern China

Climate, topography, and human activities are known to influence plant diversity. In the present study, species-abundance distribution (SAD) patterns of the shrub community were fitted, and the mechanism of contribution of 22 driving factors was assessed. The results showed that the α-diversity index exhibited no significant differences between artificial disturbance and the natural community. The Zipf and Zipf–Mandelbrot models were found to exhibit a good SAD fitting of the communities, thereby exhibiting a different diversity structure. It was observed that the SAD followed more than one rule, and the Zipf–Mandelbrot model was better than other models. The gradient boosting model indicated that precipitation in the wettest month, annual precipitation, and slope direction showed the strongest impact on plant richness. The indicator species of the artificial disturbance and natural community were identified from a multiple regression tree. Furthermore, an increase in species diversity was observed with a rise in latitude, exhibiting a single-peaked curve with increased altitude. β-diversity analysis indicated that both habitat filtering and the neutral effect influenced the establishment of the natural community, while the establishment of the artificial disturbance community was only affected by habitat filtering. Our study provides a better understanding of the ecological process of the maintenance of shrub-community diversity.

Horizontal Distribution Characteristics and Environmental Factors of Shrubland Species Diversity in Hainan Island, China

Tropical forests play a vital role in preserving world biodiversity and supporting ecological services. Moreover, the spatial distribution of species diversity and its causes are one of the core issues in community ecology. Therefore, the aim of this study was to explore the horizontal distribution characteristics of shrub community diversity in the tropical region of Hainan and reveal the relationship between species diversity and environmental factors under anthropogenic disturbances. Based on a survey of 39 shrubland plots, we evaluated shrub community diversity by calculating Hill number and Pielou evenness index. Regression analysis was employed to determine the horizontal distribution pattern, and Pearson correlation and redundancy analysis were applied to reveal the relationship between species diversity and environmental factors. The results reveal that species richness increased from west to east and the horizontal distribution of shrubland species diversity in Hainan was largely determined by rainfall and edaphic factors and not by topographic factors. Rainfall factors were the most influential. Although there was a significant human disturbance in Hainan shrublands, environmental factors were still influencing the distribution of these shrublands, and there was a lower shrub diversity in areas with poor moisture conditions, which should be studied more. Our results are of great significance to the study of tropical vegetation and regional biodiversity conservation.

Evaluating Effects of Post-Fire Climate and Burn Severity on the Early-Term Regeneration of Forest and Shrub Communities in the San Gabriel Mountains of California from Sentinel-2(MSI) Images

Studying the early changes in post-fire vegetation communities may improve the overall resilience of forests. The necessity for doing so was demonstrated by the Bobcat Fire, which seriously threatened the central San Gabriel Mountains and the Angeles National Forest in California. This study aimed to monitor and quantify the effects of climatological and topographic conditions along with burn severity on early (within 1 year) post-fire forests and shrubs community regeneration. In this study, we used Sentinel-2(MSI) intensive time-series imagery (July 2020–October 2021) to make a confusion matrix combined with 389 vegetation sample points on Google Earth Pro. The overall accuracy (OA) and the Kappa coefficient, calculated from the confusion matrix, were used as evaluation parameters to validate the classification results. With multiple linear regression models and Environmental Systems Research Institute (ESRI) historical images, we analyzed the effects of climate and slope aspects on the regeneration of post-fire forest and shrub communities. We also quantitatively analyzed the regeneration rates based on five burn severity types. The results show that the normalized burning rate (NBR) was the most accurate vegetation classification indicator in this study (OA: 92.3–99.5%, Kappa: 0.88–0.98). The vegetation classification accuracy based on SVM is about 6.6% higher than K-Means. The overall accuracy of the burn area is 94.87%. Post-fire climate factors had a significant impact on the regeneration of the two vegetation communities (R2: 0.42–0.88); the optimal regeneration slope was 15–35°; and the fire severity changed the original competition relationship and regeneration rate. The results provide four main insights into the regeneration of post-fire vegetation communities: (1) climate factors in the first regenerating season have important impacts on the regeneration of forest and shrub communities; (2) daytime duration and rainfall are the most significant factors for forests and shrubs regeneration; (3) tolerable low burn severity promotes forests regeneration; and (4) forests have a certain ability to resist fires, while shrubs can better tolerate high-intensity fire ecology. This study could support the implementation of strategies for regionalized forest management and the targeted enhancement of post-fire vegetation community resilience.

Rare phytocoenotaxonomic diversity of the steppe zone of Ukraine: analysis and applied aspects

Preservation of rare phytocenotic diversity is one of the priority tasks in the integral problem of biodiversity protection. The implementation of these tasks requires a transition to such principles as the use of a system of preventive/prophylactic and direct methods and modes of conservation depending on the type of vegetation and the homeostasis of plant communities. It was established that the state of rare groups of Ukraine has changed significantly over the past few decades, It is noted that the Steppe biome under the influence of a huge anthropogenic press not only underwent significant changes, but also lost its structure and regulatory properties, which led, in fact, to its destruction and the complete death of numerous elements. The purpose of the work was to compile information on the current state of rare groups in the steppe zone using data from ecological-cenotic and floristic studies, to assess their presence in the territories of biosphere and natural reserves and national natural parks in the region. Field research was carried out using classical geobotanical methods (detailed routing, establishment of test sites, geobotanical description). A critical analysis of the current rare phytocenophyte, the data of modern synphytosozological studies and the latest geobotanical information on the rare phytocenotic diversity made it possible to establish the modern rare phytocenophyte of the steppe zone of Ukraine. It has 321 associations of 48 formations. The forest vegetation has only 16 associations of 3 formations. Steppe vegetation is characterized by the most numerous rare phytocenophand, which is represented by 180 associations of 19 formations, grass and shrub communities of the xerotic type on outcrops and sands have 23 associations of 5 formations, 3 associations of one formation are established for swamp vegetation, halophytic vegetation is characterized by the presence of 13 associations of 5 formations. Higher aquatic vegetation is represented by 86 associations of 1 formation. Summarization of materials based on the results of geobotanical studies of rare taxa carried out in the region after the release of the state document «Green Book of Ukraine» in 2009 allowed to identify 96 associations (1 forest, 79 steppe, 7 grass and shrub communities of the xerotic type on outcrops, 3 halophytic, 6 water), which are new rare associations. The levels of their representation in biosphere reserves (BZ) and nature reserves (NP) and national natural parks (NPP) have been established. They are protected in 22 nature reserve territories (NPAs) of higher categorical ranks, in particular – in 3 BZ, 6 – PZ, 13 – NPP It was concluded that the state of protection of the rare vegetation of the region is typologically and syntaxonomically representative in the PZT system of the highest sociological rank. The level of security for most rare associations is high and average, in a small number of formations it is low. A small number of rare associations are protected in only one PZT, which is insufficient. A number of protected associations are represented by small fragments or groups with a weakened edifying value of the main components.

Carbon–water coupling and its relationship with environmental and biological factors in a planted Caragana liouana shrub community in desert steppe, northwest China

Abstract The carbon and water cycle, an important biophysical process of terrestrial ecosystems, is changed by anthropogenic revegetation in arid and semiarid areas. However, there is still a lack of understanding of the mechanisms of carbon and water coupling in intrinsic ecosystems in the context of human activities. Based on the CO2 and H2O flux measurements of the desert steppe with the planted shrub Caragana liouana, this study explored the carbon and water flux coupling of the ecosystem by analyzing the variations in gross primary productivity (GPP), evapotranspiration (ET) and water use efficiency (WUE) and discussing the driving mechanisms of biological factors. The seasonal variation in climate factors induced a periodic variation pattern of biophysical traits and carbon and water fluxes. The GPP and ET fluctuated in seasons, but the WUE was relatively stable in the growing season. The GPP, ET and WUE were significantly driven by global radiation (Rg), temperature (Ta and Ts), water vapor pressure deficit, leaf area index and plant water stress index (PWSI). However, Rg, temperature and PWSI were the most important factors regulating WUE. Rg and temperature directly affected WUE with a positive effect but indirectly inhibited WUE by rising PWSI. Plant water stress inhibited photosynthesis and transpiration of the planted shrub community in the desert steppe. When the plant water stress exceeded a threshold (PWSI >0.54), the WUE would decrease since the GPP responded more quickly to the plant water stress than ET. Our findings suggest that policies related to large-scale carbon sequestration initiatives under afforestation must first fully consider the status of water consumption and WUE.

Fire as a novel disturbance and driver of vegetation change in Nama-Karoo rangelands, South Africa

Nama-Karoo vegetation is fire naïve and therefore vulnerable to transformation by fire. This study investigated the effect of fire, a novel disturbance, on the composition and structure of shrub communities in semi-arid Eastern Upper Karoo rangelands. Nine sites across a rainfall gradient had been burnt between eight years and six months before time of sampling, whose grazing history ranged from heavy or lenient to no grazing. Fire markedly changed the composition and structure of Karoo shrublands, the nature and extent of which depended on climate regime. Non-sprouting species, including some dominant species, were extirpated by fire and replaced by previously non-dominant sprouter species. Replacement of non-sprouter by sprouter species was conspicuous for palatable and unpalatable dwarf shrubs. Under conditions that closely resemble climate change forecasts for the region, fire transformed Nama-karoo shrublands. The possibility of larger more frequent fires in the Nama-Karoo threatens to transform the vegetation, ecosystem functioning, and economy of the region. Fire has emerged as a novel agent of vegetation change in the eastern Nama-Karoo owing to a directional increase in annual rainfall over the past three decades, that may cement a state change from shrubland to grassland in an ampliative, positive feedback manner.

Continuing expansion of Narrow-leaved Cattail (<i>Typha angustifolia</i>) and decline of a provincially rare fen in the Holland Marsh, Ontario

At the time of European settlement, an extensive graminoid wetland existed at the confluence of the East and West Holland Rivers at the southern end of Lake Simcoe, Ontario. However, by 1925, clearing and draining of the marsh for specialty agriculture (i.e., market gardens) had begun and, by the 1940s, ~46% of the wetland had been cleared and another 13% was lost before 2016. Concurrent with marsh conversion has been an increase in Narrow-leaved Cattail (Typha angustifolia) in the remnant wetland. This study documents the change in the Holland Marsh wetland by delineating boundaries between marsh, fen, and shrub communities on aerial photographs taken at ~10-year intervals between 1946 and 2015 and documenting vegetation change along transects running perpendicular to tributaries bisecting the wetland. The extent of fen habitat within the Holland Marsh has been decreasing since 1946 at an average rate of 0.24 ha/year because of increases in both shrub and marsh (i.e., T. angustifolia) communities. Typha angustifolia expansion has been predominantly from along the margins of the Holland River where soil phosphorus concentration is significantly higher than in the core of the fen. Beyond 30 m from the river, vegetation dominance shifts from T. angustifolia to sedges (Cyperaceae). Managing phosphorus loading from upstream land uses will be of critical importance in protecting this habitat, which is rare in southern Ontario.

Quantifying the risk of non‐native conifer establishment across heterogeneous landscapes

Abstract Pines (genus Pinus) are cultivated extensively for forestry purposes, particularly in regions that are outside the genus' native range. The most common forestry species are also typically those most likely to escape cultivation and spread rapidly, and thus pines constitute a substantial weed problem in many regions. However, there is limited knowledge of the factors underlying the spread of pines from plantations. Assessments across heterogeneous landscapes are required to provide rigorous data to support management tools and policies aiming to protect vulnerable ecosystems from pine invasions. We examined the spread of Pinus radiata from forestry plantations over a ~9,000 km2 landscape on Banks Peninsula, New Zealand. We used ground‐based surveys from a set of viewpoints to determine tree locations, coupled with geographical information system (GIS) viewsheds to define the area surveyed. We used boosted regression trees to build a habitat model for P. radiata establishment on Banks Peninsula. We surveyed an area approximately 107 km2, recording 470 naturally established P. radiata individuals. Our habitat models suggested that proximity to the nearest plantation forest was the most important variable predicting P. radiata establishment, with individuals most likely to establish within 150 m of a plantation. Individuals were also most likely to establish in early successional shrub communities, proximate to roads, and on steeper topography. Highly grazed habitats were least vulnerable to P. radiata establishment. The slope and aspect of the source plantation influenced the distances from the plantation at which P. radiata individuals were recorded, with individuals recorded furthest away likely to have originated from plantations that were south‐facing or on steeper slopes, and therefore most exposed to strong winds. Synthesis and applications. Our findings on distances from plantations at which individuals established, vulnerable habitats, and the interactions we detected among our predictor variables, can be extended to aid management of non‐native conifer plantings elsewhere in the Southern Hemisphere. These data can be used to contribute to improvements of decision support systems that assess likely spread risk from non‐native conifer plantings. Such tools can reduce the likelihood of future pine establishment, potentially preventing biological invasions.

Comparing Elevational Patterns of Taxonomic, Phylogenetic, and Functional Diversity of Woody Plants Reveal the Asymmetry of Community Assembly Mechanisms on a Mountain in the Hengduan Mountains Region

The contributions and interaction of biotic and abiotic processes in community assembly are crucial for understanding the elevational patterns of biodiversity. The combined analyses of taxonomic, phylogenetic, and functional diversity are necessary to resolve this issue. By investigating vegetation in 24 transects sampled on Hongla Snow Mountain, in the central Hengduan Mountain Ranges in Southwest China, we delineated the elevational vegetation spectrum on the eastern and western slopes, analyzed the elevational variation in taxonomic, phylogenetic, and functional diversity of woody plant species, and compared the community structure of phylogeny and function in the low-elevational shrublands, mid-elevational forests, and alpine shrubs and meadows. The species richness, phylogenetic diversity, and functional diversity of woody plants showed nonstandard hump-shaped patterns with two peaks along the elevational gradient. The community structure of phylogeny and function (including tree height, leaf area, specific leaf area, leaf thickness, bark thickness, and wood density) clustered in the low-elevation shrub communities, being random and over-dispersed in mid-elevational forests. The phylogenic structure was over-dispersed in alpine communities, whereas the functional structure was clustered. Elevational patterns in taxonomic, phylogenetic, and functional diversity, together with the mean and variation in woody plant functional traits, suggested drought stress and freeze stress as environmental filters dominating the assembly of low and high elevation non-forest communities, and a conspicuous effect of biotic facilitation was also suggested for alpine habitats. By contrast, interspecific competition dominated the community assembly of forests at mid-elevations. The difference in biodiversity indices between the west and east slopes reflected the effects of the Indian Monsoon on the geomorphic patterns of ecosystem structure. These results increased our understanding of biodiversity patterns and underlying mechanisms in the Hengduan Mountains of Southwest China and highlighted the priorities for biodiversity conservation in this region.

Quantifying the Aboveground Biomass (AGB) of Gobi Desert Shrub Communities in Northwestern China Based on Unmanned Aerial Vehicle (UAV) RGB Images

Shrubs are an important part of the Gobi Desert ecosystem, and their aboveground biomass (AGB) is an important manifestation of the productivity of the Gobi Desert ecosystem. Characterizing the biophysical properties of low-stature vegetation such as shrubs in the Gobi Desert via conventional field surveys and satellite remote sensing images is challenging. The AGB of shrubs had been estimated from spectral variables taken from high-resolution images obtained by unmanned aerial vehicle (UAV) in the Gobi Desert, Xinjiang, China, using vegetation feature metrics. The main results were as follows: (1) Based on the UAV images, several RGB vegetation indices (RGB VIs) were selected to extract the vegetation coverage, and it was found that the excess green index (EXG) had the highest accuracy and the overall extraction accuracy of vegetation coverage reached 97.00%. (2) According to field sample plot surveys, the AGB and shrub crown area of single shrubs in the Gobi Desert were in line with a power model. From the bottom of the alluvial fan to the top of the alluvial fan, as the altitude increased, the AGB of the vegetation communities showed an increasing trend: the AGB of the vegetation communities at the bottom of the alluvial fan was 2–90 g/m2, while that at the top of the alluvial fan was 60–201 g/m2. (3) Vegetation coverage (based on the UAV image EXG index) and AGB showed a good correlation. The two conform to the relationship model (R2 = 0.897) and the expression is Y = 1167.341 x0.946, where Y is the AGB of the sample plots in units g/m2 and x is the vegetation coverage extracted by the VI. (4) The predicted AGB values of Gobi Desert shrubs using UAV RGB images based on a power model were closer to the actual observed AGB values. The study findings provide a more efficient, accurate, and low-cost method for estimating vegetation coverage and AGB of Gobi Desert shrubs.

Diversity and composition of shrubs in Behali Reserve Forest of Biswanath district, Assam, with special emphasis on Gnetum gnemon L.

The study is focused to study the diversity and distribution of shrubs in the Behali Reserve Forest. A total of 46 species of shrubs belonging to 40 genera representing 25 families were documented. Rubiaceae and Lamiaceae were the dominant families. Pycnarrhena pleniflora has the highest IVI value of (48.25) followed by Coffea benghalensis (41.1). Plotting in Raunkiaer’s frequency class distribution it was found that the shrub community of BRF is heterogeneous in nature i.e. represents uniform species diversity which does not allow the dominance of a species. Among the recorded shrubs, Pycnarrhena pleniflora, Coffea benghalensis, Boeica filiformis, Gnetum gnemon and Dalhousiea bracteata has a good population status. Gnetum gnemon on the other hand a potential NTFP of BRF has an infrequent distribution which is due to its high economic value and unregulated collection. The market value of G.gnemon and its conservation needs are also presented.

Short-interval fires increasing in the Alaskan boreal forest as fire self-regulation decays across forest types

Climate drivers are increasingly creating conditions conducive to higher frequency fires. In the coniferous boreal forest, the world’s largest terrestrial biome, fires are historically common but relatively infrequent. Post-fire, regenerating forests are generally resistant to burning (strong fire self-regulation), favoring millennial coniferous resilience. However, short intervals between fires are associated with rapid, threshold-like losses of resilience and changes to broadleaf or shrub communities, impacting carbon content, habitat, and other ecosystem services. Fires burning the same location 2 + times comprise approximately 4% of all Alaskan boreal fire events since 1984, and the fraction of short-interval events (< 20 years between fires) is increasing with time. While there is strong resistance to burning for the first decade after a fire, from 10 to 20 years post-fire resistance appears to decline. Reburning is biased towards coniferous forests and in areas with seasonally variable precipitation, and that proportion appears to be increasing with time, suggesting continued forest shifts as changing climatic drivers overwhelm the resistance of early postfire landscapes to reburning. As area burned in large fire years of ~ 15 years ago begin to mature, there is potential for more widespread shifts, which should be evaluated closely to understand finer grained patterns within this regional trend.

Identification of Lagopus muta japonica food plant resources in the Northern Japan Alps using DNA metabarcoding.

DNA metabarcoding was employed to identify plant-derived food resources for the Japanese rock ptarmigan (Lagopus muta japonica), which is registered as a natural living monument in Japan, in the Northern Japanese Alps in Toyama Prefecture, Japan, in July to October, 2015–2018. DNA metabarcoding using high-throughput sequencing (HTS) of rbcL and ITS2 sequences from alpine plants found in ptarmigan fecal samples collected in the study area. The obtained sequences were analyzed using a combination of a constructed local database and the National Center for Biotechnology Information (NCBI) database, revealed that a total of 53 plant taxa were food plant resources for ptarmigans. Of these plant taxa, 49 could be assigned to species (92.5%), three to genus (5.7%), and one to family (1.9%). Of the 23 plant families identified from the 105 fecal samples collected, the dominant families throughout all collection periods were Ericaceae (99.0% of 105 fecal samples), followed by Rosaceae (42.9%), Apiaceae (35.2%), and Poaceae (21.0%). In all of the fecal samples examined, the most frequently encountered plant species were Vaccinium ovalifolium var. ovalifolium (69.5%), followed by Empetrum nigrum var. japonicum (68.6%), Kalmia procumbens (42.9%), Tilingia ajanensis (34.3%) and V. uliginosum var. japonicum (34.3%). A rarefaction analysis for each collection period in the study revealed that the food plant resources found in the study area ranged from a minimum of 87.0% in July to a maximum of 97.5% in September, and that 96.4% of the food plant taxa were found throughout the study period. The findings showed that DNA metabarcoding using HTS to construct a local database of rbcL and ITS2 sequences in conjunction with rbcL and ITS2 sequences deposited at the NCBI, as well as rarefaction analysis, are well suited to identifying the dominant food plants in the diet of Japanese rock ptarmigans. In the windswept alpine dwarf shrub community found in the study area, dominant taxa in the Ericaceae family were the major food plant s for Japanese rock ptarmigans from July to October. This plant community therefore needs to be conserved in order to protect the food resources of Japanese rock ptarmigans in the region.