Plant Cover Research Articles

Plant and soil microbial composition legacies following indaziflam herbicide treatment

Land stewards in dryland ecosystems across the western U.S. face challenges to manage the exotic grass Bromus tectorum (cheatgrass), which is a poor forage, is difficult to remove, and increases risk of catastrophic fire. Managers may consider using indaziflam (Rejuvra™), a relatively new pre-emergent herbicide, which may reduce cheatgrass cover within drylands. However, few studies have explored the effects of indaziflam on non-target organisms. We tested how indaziflam application impacted cover and biomass of native and exotics within the plant community and composition and diversity of the soil microbiome by comparing untreated and treated arid shrubland sites in Boulder County, Colorado, USA. We found that indaziflam application decreased cheatgrass cover by as much as 80% and increased native plant cover by the same amount. Indaziflam application also was associated with increased soil nitrate (NO3−), decreased soil organic matter, and had a significant effect on the composition of the soil microbiome. Microbial community composition was significantly related to soil NO3−, soil organic matter, soil pH, and native species and cheatgrass biomass. An indicator species analysis suggested that indaziflam application shifted microbial communities. In untreated sites, ammonia-oxidizing bacteria Nitrosomonadaceae and nitrogen-digesting Opitutaceae and the fungi Articulospora proliferata were found. While in treated sites, ammonia-oxidizing archaea which are associated with intact drylands, Nitrososphaeraceae and toxin digesters and acidic-soil species Sphingomonas and Acidimicrobiia were significantly associated. Overall, these results demonstrate that indaziflam application can increase native plant recruitment, while also affecting soil properties and the soil microbiome. The findings from this study can be used to inform decision-making during dryland restoration planning process as indaziflam use may have benefits and unknown long-term consequences for the biogeochemistry and microbial ecology of the system.

ANALYSIS OF VEGETATION COVER IN COMMUNITIES OF UZHGOROD DISTRICT BASED ON NBR-INDEX VALUES

An important resource of the Uzhgorod district and its fourteen territorial communities is the plant cover, which is characterized by a significant phytocenotic diversity. The landscapes of the Uzhgorod district have been undergone significant anthropogenic changes, especially in the flat part, where agricultural lands with mainly arable land and pastures. Numerous vegetation indices are used for the monitoring of the vegetation cover condition using remote sensing data, among which NBR is the normalized burn ratio index. Such an index is an informative quantitative indicator of the state of vegetation in general and as a result of the impact of fires in particular. To calculate and compare the NBR index, images with minimum cloud cover for August-September 2023 were used. The selected period is due to the temperature peak and seasonal burning of dry vegetation. Also, at the end of summer and beginning of autumn, the harvesting of cereals and other agricultural crops begins, as a result of which there is a significant decrease in vegetation cover, which affects the reflectivity of the surface and the value of the NBR index. The values of community areas with negative values of the NBR index and their correlation with the total area and population were analyzed.

Bioguided isolation and identification of the protodioscin isomers from Brachiaria ruziziensis L. as inhibitors of growth of Euphorbia heterophylla L.

A bioguided identification of the phytotoxic compounds of the Brachiaria ruziziensis L. on the weed species Euphorbia heterophylla L. was conducted. From the butanolic fraction of B. ruziziensis it was separated an active subfraction (Subfraction III) that was demonstrated to contain the steroidal saponins. These substances were determined as protodioscin and protonedioscin by 1H and 13C NMR analysis. b-ethyl glucose was also identified, but it represented only 2.4% of the subfraction III. The effects of pure protodioscin were very similar to those caused by Fraction III or saponins isolated from B. ruziziensis. Root length was the most sensitive variable and the germination indices were little modified. The calculated ID50 for primary root inhibition was 390.1 ± 112.7 µg/ml and 359.5 ± 44.6 µg/ml for saponins and pure protodioscin, respectively. b-ethyl glucose did not cause significant modifications in the germination and seedling growth when assayed at a concentration range of 100 to 1000 µg/ml. These results suggest that protodioscin isomers are the causative compounds of the inhibitory effects on growth of E. heterophylla. These compounds are possibly involved in the reported ability of B. ruziziensis in reducing the emergence and the growth of weed species when used as a cover plants. This finding confirms the potential of the utilization of B. ruziziensis for weed management options in the field.

The Impact of Exogenous Organic Matter on the Properties of Humus Compounds of Soils Developing on a Reclaimed Fly Ash Landfill

Fly ash does not contain organic matter to initiate soil-forming processes and the proper development of plant cover. Therefore, in the reclamation of fly ash landfills, an integrated approach is required, including the introduction of exogenous organic matter into the top layer of ash. This study assessed changes in the content and quality of organic matter in soils developing on a reclaimed fly ash landfill. This study included reclaimed areas without the introduction of EOM (RV_1—the direct introduction of plants) and with the introduction of EOM (RV_2—surface humus and RV_3—sewage sludge). In samples taken 15 years after reclamation, the contents of total organic carbon (TOC) and total nitrogen (TN), the fractional composition of organic matter, the susceptibility of organic matter to oxidation, and soil carbon management indices (carbon pool index (CPI), C lability (L), lability index (LI), and carbon management index (CMI)) were determined. The study results showed that the use of EOM in the reclamation of the ash dump significantly increased the content and improved the quality parameters of organic matter and thus influenced the initiation of the process of organic matter accumulation. In RV_1 soil, the accumulation of carbon resources was only found in the topsoil. An increase in carbon resources in the 15–40 cm layer was only noted in the variants in which EOM was introduced (RV_2 and RV_3). Carbon management indices showed that organic matter transformations covered only the top layers of these soils and were closely related to the EOM inflow. The interdependence of the CPI and L was most beneficial in the soil reclaimed with sewage sludge. In the soil of this reclaiming variant, the CMI had a value above 100, which indicates the initiation of the soil-forming process. Significant differences between the assessed reclamation variants were confirmed by means of PCA based on organic matter quality indicators. The organic matter content and quality indicators were the most favorable in the soil of variant RV_3. The obtained results confirmed that the introduction of EOM into the top layer of fly ash has a beneficial effect on the accumulation and quality indicators of organic matter and thus on the development of the soil-forming process in Technosols developing on a reclaimed fly ash landfill.

Microbial diversity and cover plants in de-sealed urban soil as strategies for mitigating anthropogenic volatile organic compounds

Urbanization exacerbates soil degradation, compromising global soil health and biodiversity. To reduce this, strategies for soil de-sealing and bioremediation are necessary. In a mesocosm experiment using a de-sealed soil from an urban site as substrate, an inoculum of arbuscular mycorrhizal fungi (AMF) and two cover plants, Cynara cardunculus L. and Trifolium repens L., were utilized to assess their effects on volatile organic compound (VOC) emissions and soil microbial community dynamics. The soil status was investigated employing soil VOC and metabarcoding analyses. Our results showed that the soil VOC emission was mainly composed by anthropogenic derived VOCs, especially arene and furan classes. These two classes were shown to be less concentrated in C. cardunculus soils, with and without AM fungal inoculation, suggesting a positive impact of these conditions on soil health restoration. Additionally, AM fungal inoculation of C. cardunculus resulted in increased bacterial alpha diversity, with enhanced Proteobacteria/Acidobacteria, Cyanobacteria/Chloroflexi, and Fungi/Bacteria ratios, suggesting an improvement in soil quality conditions. In our experimental conditions, order Chloroflexales and specific bacterial genera, including Ralstonia, Delftia, Ramlibacter, were identified as contributors to VOC degradation, highlighting their adaptability in contaminated environments. Overall, this study provided evidence on the importance of integrating AM fungal inoculation and specific flowerbed/ornamental plants in urban soil management after de-sealing processes.

Highway to health: Microbial pathways of soil organic carbon accrual in conservation farming systems

Increasing pressure on arable land related to climate change mitigation and adaptation within recent policy frameworks has generated widespread interest in the effect of sustainable agricultural management practices on soil organic carbon (SOC) storage. Current frameworks point to soil microorganisms and their functioning as the key drivers of SOC accrual. This study provides a comprehensive on-farm assessment of changes in SOC formation pathways (physico-chemical and microbial) and the underlying drivers comparing three soil use systems: conservation and conventional farming systems as well as permanently vegetated adjacent reference soils (i.e., field margins) without agricultural land-use.Overall, our results indicated substantial increases in extractable organic carbon (+22 %), microbial biomass carbon (+29 %) and necromass carbon stocks (+11 %) in soils of conservation farming systems as compared to conventional farming systems. Differences between all three soil use systems were strongly pronounced in the surface soil (0–5 cm) and declined in deeper soil layers. Structural equation modelling revealed a varying influence of SOC storage pathways among soil use systems, with microbial-mediated (‘in-vivo’) turnover and direct sorption being the most dominant pathways. Moreover, diversity of crop rotation and tillage intensity were identified as the most important factors influencing extractable organic carbon and carbon-liberating enzyme activity within conservation farming management. Our on-farm approach demonstrates that enhanced bioavailable carbon inputs and reduced soil disturbance are the key drivers for microbially-controlled SOC accrual in arable soils and that conservation farming systems with extended plant coverage and increased crop diversity can substantially advance the restoration of soil health.

Trophic activity of pedofauna in two gardens of Saint-Petersburg (experience of using the express bait-lamina test methid)

The plant and soil cover of cities functions as their ecological framework. Soil invertebrates play an important role in urban ecosystems. Trophic activity of pedofauna is an integral indicator of its condition. The trophic activity of macroand mesopedofauna in the soils of the gardens of the Russian Museum (St. Petersburg) was determined by the express method baitlamina test. The average values of the degree of consumption of bait by pedobionts amounted to 10.9 ± 1.6% for the Summer Garden and 8.5 ± 3.5% for the Mikhailovsky Garden. The variability of trophic activity indices between different sample areas was established – in the Summer Garden it varies from 2 ± 6.2% to 21.8 ± 8.4%, and in the Mikhailovsky Garden – from 2.8 ± 4.5% to 19.3 ± 8.8%. Differences in trophic activity within the vegetation season were noted. The lowest degree of bait consumption (less than 2%) was observed in the driest and hottest months in the middle of the vegetation period, and the highest (within 19–22%) – at the beginning and end of the vegetation period under the most favorable hydrothermal conditions.

Phenotypic plasticity accounts for changes in plant phosphorus‐acquisition strategies from mining to scavenging along a gradient of soil phosphorus availability in South American Campos grasslands

Abstract Plants have evolved numerous traits to acquire phosphorus (P). Correspondingly, soil P availability modulates the functional composition of many plant communities. However, it is unclear to what extent plant species modulate the expression of different P‐acquisition strategies (phenotypic plasticity). Moreover, how variation in soil‐P availability interacts with plant phenotypic plasticity and species turnover to determine what P‐acquisition strategies are present in highly diverse communities? To address these questions, we assessed associations between plant‐available soil P and the magnitude of several P‐acquisition traits in both individual species and plant communities in Campos grasslands. Root phosphatase activity (phosphomonoesterase and phosphodiesterase), leaf manganese (Mn) concentration (a proxy for carboxylate concentration in the rhizosphere) and arbuscular mycorrhizal (AM) colonization were assessed in 105, 52 and 54 native plant species, respectively, sampled across three to seven plant communities with contrasting concentrations of plant‐available soil P. Furthermore, root diameter and plant cover of those species were also quantified. Variation in P‐acquisition strategies among species was large: 157‐ and 118‐fold for phosphatases, 96‐fold for leaf [Mn] and 39‐fold for AM colonization. Between half and two‐thirds of the variation in community‐weighted mean P‐acquisition traits was accounted for by the interactive factors plant‐available soil P, soil pH and root diameter. At low‐P availability, phosphatases and carboxylate exudation (P‐mining traits) and thin roots predominated, particularly at low soil pH. At higher P availability, AM associations (P‐scavenging trait) and thicker roots were more common. Synthesis. Phenotypic plasticity was a major source of variation in the response of P‐acquisition traits to soil properties, particularly for P‐mining traits. Our results reveal that the plasticity of the expression of plant P‐acquisition strategies in individual species was more important than changes in species presence or cover as a mechanism underlying shifts between P‐mining and P‐scavenging strategies as plant P availability varied across communities.

Enhancing Bird Diversity in Urban Parks: Insights from the Futian Mangrove Ecological Park, Shenzhen

Small urban parks and green spaces, serving as essential recreational venues for city residents, also play a vital and irreplaceable role in maintaining urban biodiversity. It is of great importance to design and plan these areas in a way that integrates multiple habitats for various species while accommodating residents’ usage. This study, carried out at the Futian Mangrove Ecological Park located in Shenzhen, Guangdong Province, China, chose birds as indicator species to assess biodiversity within the park. Site inventory was undertaken from May to September 2022 and from October 2022 to April 2023. We quantitatively described the park’s habitats by examining primary environmental factors, along with 3 primary environmental factors and 11 secondary factors. A correlation analysis was then performed between these factors and bird diversity to gain insights into birds’ habitat preferences across different habitat types and at a finer scale of plant communities. Furthermore, bird clusters in the study case were categorized by foraging guilds and foraging patterns, and their distributions were studied at both the habitat patch scale and the plant community scale. Our findings reveal that, at the habitat patch scale, water surface area and grass coverage significantly positively impact bird diversity. At the plant community scale, plant communities with different structural characteristics vary in their importance to bird clusters with distinct characteristics. In areas with high human disturbance, shrub coverage is crucial for bird habitat protection. Additionally, we discovered that the impact of anthropogenic sound differs among bird species, highlighting the complexity of human disturbance factors on bird habitat preferences. Accordingly, we proposed several design recommendations aimed at enhancing bird diversity in parks, including increasing water body areas, reducing the distance between habitats and water surfaces, enhancing herbaceous plant coverage, and controlling anthropogenic sound.

Classification of plants based on time-series SAR coherence and intensity data in Yancheng coastal wetland

ABSTRACT Investigating coastal wetland plant communities is of great significance for wetland monitoring due to the important functions of coastal wetlands, such as maintaining biodiversity and mitigating global climate change. Current studies on wetland plants mostly rely on optical data, with few utilizing synthetic aperture radar (SAR) data. Moreover, these studies often analysed single temporal SAR data, which limited the exploration of the valuable information present in time-series SAR data. Therefore, in this paper, we proposed a technique for mapping coastal wetland plant types based on time-series SAR coherence and intensity data to fully utilize the information from these data. We utilized Sentinel-1 Single Look Complex (SLC) images covering the Yancheng coastal wetland for the entire year of 2021 to investigate the effectiveness of using dual-polarization interferometric coherence and intensity-derived information from time-series Sentinel-1 data as features for classification. Plant classification was conducted using support vector machine (SVM) and random forest (RF) methods. Our results demonstrated that integrating time-series dual-polarization coherence and intensity-derived information resulted the best classification accuracy, with an overall accuracy (OA) of 89.79% and a Kappa coefficient of 0.858. This highlights the effectiveness of combining coherence and intensity data from time-series Sentinel-1 for monitoring plant cover in coastal wetlands.

Habitat management interventions for a specialist mid- successional grassland butterfly, the Lulworth Skipper

Evidence-based management is needed to reverse declines in insect abundance. The Lulworth Skipper Thymelicus acteon is a range-restricted and declining species in the UK and northern Europe associated with mid-successional grassland, which presents management challenges because interventions are necessary to prevent long-term habitat deterioration but can result in short-term reductions in quality. In addition, site management should be compatible for the focal species and for wider plant and insect diversity. We conducted factorial experimental management trials to understand effects of cutting and rotovation on the height and structure of vegetation containing the larval host plant Tor-grass Brachypodium rupestre. We monitored vegetation height, B. rupestre cover and plant diversity, and T. acteon larval presence over four years. Rotovation and cutting differed in their effects on habitat structure and larval occupancy relative to controls. Vegetation height and host plant cover, the most important components of habitat quality for T. acteon, were faster to recover to suitable levels on cut plots. However, larval occupancy increased more quickly on rotovated plots, where plant species diversity was also higher. Results suggest that due to initial negative impacts of interventions on T. acteon occupancy, low frequency or low-intensity management, such as managing sections of a site every three years, is advisable. Our results show that rotovation or cutting the sward can be suitable for mid-successional grassland species such as Lulworth Skipper on sites where grazing might be problematic. Rotational grazing or rotovation can maintain suitable conditions for habitat specialist insects requiring a range of different grassland conditions, serving wider conservation goals.

Biodiversity and Abundance of Angiosperms and Environmental Resilience in the Tidal Range of Yuanjiang Dry–Hot Valley, Southwestern China

Yuanjiang dry–hot valley is located in the southwest of mainland China. It is a sparsely vegetated area with a fragile arid ecosystem. Although the valley previously had forest cover, it has become a tropical montane savannah in recent decades. Mechanisms controlling plant species distribution in such dry–hot valleys are unclear. Clarifying this will be beneficial to sustainable ecosystem management in dry–hot valleys. This study explored the relationship between diversity patterns of plant species and their environments in the lowland of this dry–hot valley. To achieve this, transects and plots were arranged along the river channel. Alpha and beta diversity indices were calculated to quantify biodiversity changes between species and environments. Estimated species, rarity, and abundance indices were also utilized to examine the correlation among species, their population size, and their environment: Species_estimated (expected number of species in t pooled plots), Singletons (the number of species with only one individual in t pooled plots), Uniques (the number of species living in one plot in t pooled plots), ACE (species richness estimator with coverage-based abundance), ICE (species richness estimator with coverage-based incidence), and Chao2 (species richness estimator extrapolated from Singletons). Fifty years of meteorological records, including temperature and precipitation, were utilized as climate variables. The results indicated the following findings: (1) alpha diversity was higher closer to the river, whereas the beta diversity was higher towards the lower sections of the river (Bray–Curtis < 0.5), but this trend was reversed in the perpendicular transects; (2) total phosphorous (TP) and total potassium (TK) were higher on flatter ground, tending to be associated with raised nitrogen (TN) and organic matter (OM); (3) soil nutrients were higher towards the lower sections of the river, corresponding to an increased number of species; (4) water supply determined plant distribution, with soil condition determining water retention; (5) the estimated species and their rarity and abundance indices were associated with proximity to the river, indicating heterogeneity of habitats and soil condition; and (6) fern species could be used as indicators representing the xeric environment of Yuanjiang dry–hot valley. Plant cover was reduced at low altitudes, with high temperatures and a low water supply. These results draw attention to the need for specific policy formation to protect the microhabitats and manage the environment of the Yuanjiang valley.

Predation dynamics of Rhodeus sinensis on Procambarus clarkii larvae: Behavioral patterns and aquatic plant refuge effects in crayfish aquaculture

Non-target fish are frequently present in crayfish aquaculture systems, yet limited research has explored their predatory impacts on crayfish larvae. To address this gap, three experiments were conducted to examine the predation dynamics of Rhodeus sinensis on Procambarus clarkii larvae, focusing on the effects of predator sizes, group sizes, and aquatic plant refuges. In experiment 1, Cox proportional hazards regression model revealed that P. clarkii larvae (8.40 mm and 11.30 mm) faced heightened predation risks from R. sinensis, particularly when the predator’s weight exceeded 2 g. Predation mortality significantly rose with increasing predator size. P. clarkii larvae primarily sought refuge in bottom corners and under heating rods, as indicated by Self-Organizing Map. Experiment 2, analyzed with Bayesian Additive Regression Tree, demonstrated that group predation of R. sinensis significantly enhanced predatory efficiency on larger crayfish larvae, resulting in reduced time to the first attack, increased total number of attacks and extended total attack duration. Experiment 3 disclosed that casualty and mortality rates of crayfish larvae markedly decreased when aquatic plants coverage exceeded 20 %, irrespective of plants types. Under predation pressure, crayfish larvae exhibited a preference for microhabitats on and under aquatic plants, indicating an adaptive behavior in response to predation. These findings underscore the susceptibility of P. clarkii larvae to predation by R. sinensis and suggest maintaining a 20 % aquatic plant coverage as an effective management strategy to mitigate predation risks and support juvenile crayfish survival in aquaculture systems.

Revealing How Human Activity and Native Plants Outshine Climate in Shaping New Invasive Alien Plant Elevational Patterns in Nature Reserves

ABSTRACTAimWe aim to investigate whether invasive alien plants introduced at different times exhibit variations in elevational distribution patterns and to explore the correlations of these patterns with climate, native plants and human activity.LocationGuangxi, China.MethodsWe recorded plant richness and cover across elevational gradients at 25–34 sites within each reserve, utilising 84–134 roadside plots per site. Using generalised linear mixed model (GLMM), we assessed the impacts of climate, native plants and human activity on the distributions of all, old and new invasive alien plants across the region and within the nature reserves.ResultsAt regional scales, the cover of all, new and old invasive alien plants decreased with increasing elevation, while only the richness of old invasive alien plants exhibited a similar pattern. Contrasting patterns were observed in Dayao Mountain, where the cover of old invasive alien plants decreased while the cover of new invasive alien plants increased. The richness patterns of all and new invasive alien plants were opposite between Dayao Mountain and Yachang Orchid. Moreover, native plant richness was negatively correlated with the richness of invasive alien plants, while interference intensity positively affected new invasive alien plants at both regional and reserve scales. At the regional scale, native plant richness accounted for 78.27%, 91.94% and 60.9% of all, old and new invasive alien plants respectively. Interference intensity accounted for 33.85% of the variation in new invasive alien plants. Annual mean temperature positively influenced the cover of all and old invasive alien plants at both regional and reserve scales, explaining 36.91% and 74.28% of their regional variation. Additionally, interference intensity and distance to human settlements positively impacted the cover of new invasive alien plants, contributing to 50.95% and 31.92% of their variation at regional scales.Main ConclusionThe distinct distribution patterns of old and new invasive alien plants highlight the significance of residence time in understanding their dynamics. Climate factors constrain the cover distribution of all and old invasive alien plants, whereas interference intensity and distance to settlements determine the distribution of new invasive alien plants. Notably, native plants play a vital role in preventing the establishment and spread of invasive alien plants within nature reserves, and their effectiveness increases with longer residence times. Our findings highlight the critical importance of minimising human interference and conserving native species for the effective management of invasive alien plants in nature reserves.

Native Gramineae outperform Leguminosae in enhancing ecosystem multifunctionality during semiarid desert steppe restoration

The effects of reseeded native Gramineae and Leguminosae species on the multifunctionality of desert steppe have remained unclear. Therefore, we examined a semiarid desert steppe that was reseeded 5 years earlier with a dominant native Gramineae species, Agropyron mongolicum; a dominant native Leguminosae species, Lespedeza potaninii; and a 1:1 reseeded mixture of A. mongolicum × L. potaninii. We evaluated the changes in plant communities and soil properties and then quantified aboveground ecosystem multifunctionality (AEMF), belowground ecosystem multifunctionality (BEMF), and overall ecosystem multifunctionality (EMF) using an averaging approach. Compared with the native steppe without reseeding, both reseeded A. mongolicum and A. mongolicum × L. potaninii increased fine root volume, plant height, plant cover, aboveground biomass (AGB), belowground biomass (BGB), soil water storage (SWS), soil organic carbon, light fraction organic carbon, labile organic carbon, total nitrogen (TN), nitrate nitrogen, and total phosphorus (P), but decreased soil bulk density. However, reseeded L. potaninii increased coarse root volume, plant height, plant cover, AGB, BGB, and SWS but decreased plant richness, plant diversity, TN, and total P. In addition, reseeded A. mongolicum and A. mongolicum × L. potaninii increased AEMF, BEMF, and overall EMF, but reseeded L. potaninii only increased AEMF. Further analysis indicated that the fine roots played a crucial role in improving individual ecosystem functions and eventually in determining EMF. Therefore, the reseeding of a desert steppe with Gramineae species has greater potential than with Leguminosae species for improving EMF, since Gramineae species have greater fine roots volume than Leguminosae species.

The impact of juniper removal on shrubs and understory vegetation and its implications for sagebrush dependent vertebrate herbivores

The expansion of trees into previously grass- and shrub- dominated ecosystems is a global phenomenon threatening ecosystem integrity and function in encroached systems, including the North American sagebrush biome. This ecosystem is currently in peril, threatened in part by juniper (Juniperus sp.) encroachment. Sagebrush (Artemisia sp.) ecosystems contain a diversity of forage, including grasses, forbs, and shrubs, that serve as a key food source for vertebrate herbivores. Removal of encroached juniper has been used by land managers as a widespread restoration technique in sagebrush ecosystems, however, the long-term impact of this restoration action on shrubs and understory vegetation has not been thoroughly examined in the context of sagebrush dependent vertebrate herbivores. In 2020 and 2021, we studied shrub and understory vegetation response to juniper treatment in the sagebrush of northern Nevada and northeastern California. Juniper treatments completed between 2008 and 2020 were surveyed and sampled to assess the impact of this restoration action on grasses, forbs, and shrubs over time. Forage biomass was higher in old treatments than untreated reference sites, which was a trend that persisted across all vegetation functional groups. Differences in plant cover were slight or had inconsistent nonlinear trends between reference sites and treatments. Forage from treated sites had higher crude protein levels than forage from untreated sites, although the nutritional difference was slight. Our results suggest that juniper treatments that increase forage quantity and improve forage quality may benefit sagebrush dependent wildlife or domestic livestock in conifer-encroached ecosystems.

Investigation and Simulation Study on the Impact of Vegetation Cover Evolution on Watershed Soil Erosion

Soil erosion has always been a critical issue confronting watershed environments, impacting the progress of sustainable development. As an increasing number of countries turn their attention to this problem, numerous policies have been enacted to halt the progression of soil erosion. However, policy-driven interventions often lead to significant changes in watershed vegetation coverage, under which circumstances, the original sediment erosion models may fall short in terms of simulation accuracy. Taking the Kuye River watershed as the research subject, this study investigates soil erosion data spanning from 1981 to 2015 and utilizes the Revised Universal Soil Loss Equation (RUSLE) model to simulate soil erosion. It is found that the extensive planting of vegetation after 2000 has led to a rapid reduction in soil erosion within the Kuye River watershed. The original vegetation cover and management factor (C) proves inadequate in predicting the abrupt changes in vegetation coverage. Consequently, this study adopts two improved plant cover and management factor equations. We propose two new methods for calculating the vegetation cover and management factor, one using machine learning techniques and the other employing a segmented calculation approach. The machine learning approach utilizes the Eureqa software (version11.0, Cornell University, New York, American) to search for the relationship between Normalized Difference Vegetation Index (NDVI) and C, ultimately establishing an equation that describes this relationship. On the other hand, the piecewise method determines critical values based on data trends and provides separate formulas for C above and below these critical values. Both methods have achieved superior calculation accuracy. Specifically, the overall data calculation using the machine learning method achieved an determined coefficient (R2) of 0.5959, while the segmented calculation method achieved an R2 of 0.6649. Compared to the R2 calculated by the traditional RULSE method, these two new methods can more accurately predict soil erosion. The findings of this study can provide valuable theoretical reference for water and soil prediction in watersheds.

Soil cover heterogeneity associated with biocrusts predicts patch-level plant diversity patterns

ContextSoil resource heterogeneity drives plant species diversity patterns at local and landscape scales. In drylands, biocrusts are patchily distributed and contribute to soil resource heterogeneity important for plant establishment and growth. Yet, we have a limited understanding of how such heterogeneity may relate to patterns of plant diversity and community structure.ObjectivesWe explored relationships between biocrust-associated soil cover heterogeneity and plant diversity patterns in a cool desert ecosystem. We asked: (1) does biocrust-associated soil cover heterogeneity predict plant diversity and community composition? and (2) can we use high-resolution remote sensing data to calculate soil cover heterogeneity metrics that could be used to extrapolate these patterns across landscapes?MethodsWe tested associations among field-based measures of plant diversity and soil cover heterogeneity. We then used a Support Vector Machine classification to map soil, plant and biocrust cover from sub-centimeter resolution Unoccupied Aerial System (UAS) imagery and compared the mapped results to field-based measures.ResultsField-based soil cover heterogeneity and biocrust cover were positively associated with plant diversity and predicted community composition. The accuracy of UAS-mapped soil cover classes varied across sites due to variation in timing and quality of image collections, but the overall results suggest that UAS are a promising data source for generating detailed, spatially explicit soil cover heterogeneity metrics.ConclusionsResults improve understanding of relationships between biocrust-associated soil cover heterogeneity and plant diversity and highlight the promise of high-resolution UAS data to extrapolate these patterns over larger landscapes which could improve conservation planning and predictions of dryland responses to soil degradation under global change.

How often are ecosystems top-down controlled? Experiments in grassland, grasshopper, and bird systems over time and space.

Ecosystems are frequently considered to be controlled by predation (top-down). Experiments examined this in four bird/spider/grasshopper/prairie habitats over 34 years, employing in each habitat three 100 m2 bird exclosures and controls (121 habitat/year cases) where plant, grasshopper, and spider abundances were measured. Top-down control (plants decrease and grasshoppers increase with bird exclusion) was observed in only 13.2% of cases, while plants increased and grasshoppers decreased in 33.1% of cases, plants decreased and grasshoppers decreased in 25.6% of cases, and plants increased and grasshoppers increased in 28.1% of cases. Therefore, top-down control was not common and system responses were not constant, but varied among sites, years, and directionally over time with climate change. This diversity of responses is expected given the variety of underlying processes in complex ecosystems. For example, decision tree/discriminant analysis found that plant decreases and increases with bird exclusion were correctly identified in 78.3% of cases by grasshopper hatchling abundance, plant cover, and annual net primary production (ANPP), while grasshopper decreases and increases with bird exclusion were correctly identified in 76.7% of cases by edible plant biomass per grasshopper hatchling, grasshopper hatchling abundance, and large grasshopper abundance. Analysis of other system-wide terrestrial trophic experiments indicates that the variety of responses observed by us over time and space may be common so that system-wide trophic responses may, in general, be more variable than either top-down or bottom-up as often considered.

How does the taxonomic and functional structure of plant communities differ between riverine and palustrine swamps?

AbstractQuestionsHow does the type of swamp, that is, riverine vs palustrine, shape understorey and overstorey plant communities? Beyond swamp type, how do spatial, topographic, soil and landscape characteristics determine the taxonomic and functional structure of swamp communities?LocationSouthern Québec, Canada.MethodsWe sampled riverine and palustrine swamp plant communities in two watersheds within two ecoregions with contrasting land use. At the site scale (n = 56), we analyzed differences between riverine and palustrine swamps in plant richness and cover, species composition, and mean and dispersion values for ecological and morphological traits. At the plot scale (n = 213), we assessed the relative influence of a set of environmental parameters on species richness and cover, as well as on trait values using mixed models and on species composition using redundancy analysis.ResultsSpecies composition and the mean value of traits varied significantly between the two types of swamps. While riverine swamps hosted more non‐native species and were composed of more mesophilic species, shorter in height and with dominant resource acquisition strategies, palustrine swamps sheltered more non‐vascular taxa and tall hygrophilous vascular species with more conservative resource strategies. The surrounding landscape and local microtopography within swamps had a significant effect on plant community structure. Species diversity and trait dispersion increased from agricultural‐dominated to forest‐dominated landscapes, and from homogeneous to heterogeneous substrates.ConclusionsHabitats provided by riverine and palustrine swamps are complementary for wetland biodiversity. Our results underline the need to develop conservation plans to protect a wide variety of freshwater swamp types; for example, management actions that maintain or promote heterogeneous topographic forms at the site scale, and continuity of forest cover at the landscape scale.