Forb Biomass Research Articles

Increased availability of preferred food and decreased foraging costs from degraded grasslands lead to rodent pests in the Qinghai-Tibet Plateau

The increased population density of rodent species during ongoing grassland degradation further deteriorates its conditions. Understanding the effects of grassland degradation on rodent feeding habits is of great value for optimizing grassland management strategies. In this study, lightly degraded (LD), moderately degraded (MD), severely degraded (SD), and reseeded grassland (RG) were selected and their plant resources and soil physical properties were investigated. In addition, the study usedITS2barcode combined with the Illumina MiSeq sequencing method to analyze the food composition and proportion of plateau zokors in different grassland conditions. The results showed that, with grassland degradation, plant biomass decreased, but the relative proportion of forbs increased (LD: 32.05 ± 3.89%; MD: 28.97 ± 2.78%; SD: 49.16 ± 4.67% and RG: 10.93 ± 1.53%). Forbs were the main food of the plateau zokor, accounting for more than 90% of their diet, and the animal had a clear preference forPotentillaspecies; the soil compaction of feeding habits showed a decreasing trend in the 10–25 cm soil layer, suggesting a decreased foraging cost. Nutritional analysis showed that the stomach content of crude protein in zokors feeding on MD grassland was significantly higher than that of animals feeding on the other grassland types. Structural equation modeling showed that soil physical properties and the relative biomass of forbs had significant (P< 0.05) and extremely significant (P< 0.001) impacts on the population density of plateau zokors, with direct impact contribution rates of 0.20 and 0.63. As the severity of grassland degradation increased, although the aboveground and underground biomass of the plants decreased, the proportion of food preferred by the plateau zokor increased, and the corresponding changes in the feeding environment resulted in decreased foraging energy expenditure, thereby increasing the suitability of the degraded grassland for the plateau zokor. Compared with degraded grassland, the food diversity and evenness of zokors increased, the food niche width enlarged, and the proportion of weeds decreased in RG, which increased the difficulty of obtaining food. Reseeding in grassland management is therefore an effective way to control plateau zokors.

Invertebrate herbivory accelerates shift towards forbs caused by warming in a sedge‐dominated alpine meadow

AbstractInvertebrate herbivory is suggested to modulate community shifts caused by climate warming in grasslands. However, experimental evidence is lacking, especially in high elevation areas. We examined the interactive effect of experimental warming and the grassland caterpillar Gynaephora alpherakjj, a typical invertebrate herbivorous insect with sedge preference, on the structure of plant community in a sedge‐dominated alpine meadow in the Tibetan Plateau. We manipulated both herbivore and temperature in a full factorial field experiment using passive warming chambers over one plant‐growing season. Results show that simulated warming significantly increased the aboveground plant biomass (APB) of forbs and total APB, while the presence of caterpillars significantly decreased sedge APB and total APB. The increase in consumption of sedges by caterpillars under warmed conditions can largely be ascribed to the increase in feeding time of caterpillars. Importantly, the presence of caterpillars significantly decreased the APB ratio of sedges to forbs in the warmed but not in the unwarmed chambers. These results suggest that with a warming climate, invertebrate herbivory could accelerate community shifts from sedge dominance to forb dominance in only one plant‐growing season in the Tibetan alpine meadow. This shift would reduce the biomass of high‐quality forage and further threaten animal husbandry in this area. Considering the harm of G. alpherakjj to grasslands, its population should be controlled more strictly under the global warming scenario.

Effect of Plateau Pika Disturbance on Plant Aboveground Biomass of Alpine Meadows at Two Different Scales.

Disturbance by small burrowing herbivores often has an impact on plant aboveground biomass of grassland because it makes grasslands into a mosaic of discrete vegetated surfaces and bare soil patches. This study focuses on the plateau pika (Ochotona curzoniae) to investigate the effect of the disturbance by a small burrowing herbivore on plant aboveground biomass through upscaling the quadrat scale to the plot scale across five sites. This study showed that the plateau pika disturbance reduced sedge biomass and increased forb biomass. In contrast, they did not affect plant community biomass, grass biomass and legume biomass at the quadrat scale across the five sites. At the plot scale, that is, when the bare soil patches with a lack of plants were considered, plateau pika disturbance induced lower aboveground biomass of the plant community, sedge and legumes, while it had no relationship with grass biomass and forb biomass. As the disturbance intensity increased, the aboveground biomass of the plant community and sedge decreased, whereas the grass biomass showed a hump-shaped trend. These results indicate that plateau pika disturbance might be not beneficial to alpine meadows given the aboveground biomass of the plant community at the plot scale. In contrast, the intermediate disturbance intensity improves the grazing quality of alpine meadows through the higher grass biomass. The findings of this study imply that the plot scale is better than the quadrat scale to investigate the influence of the disturbance by a small burrowing herbivore on the plant aboveground biomass, and that management of a small burrowing herbivore needs to consider its disturbance intensity.

Aboveground net primary productivity was not limited by phosphorus in a temperate typical steppe in Inner Mongolia

AbstractPhosphorus (P) is an essential element for plant growth, however, whether the aboveground net primary productivity (ANPP) of typical steppe was limited by P remains obscure. To detect the effects of P addition on primary productivity and aboveground biomass of different plant functional groups both under ambient and N addition conditions, ANPP and aboveground biomass of grasses and forbs were measured from 2016 to 2020 on a 16-year N and P addition experiment platform in a temperate typical steppe in Inner Mongolia. The soil available N and P concentrations were also determined to test the relationship between ANPP and the availability of soil nutrients. We found that P addition under ambient condition had no significant effect on ANPP and the aboveground biomass of grasses and forbs. However, under N addition, P addition significantly increased ANPP and the aboveground biomass of forbs. Furthermore, soil available N and P concentrations were increased significantly by N and P addition, respectively. Moreover, there was no significant correlation between ANPP and soil available P concentration, while ANPP was positively correlated with soil available N concentration. These results suggest that P is not the key factor limiting the primary productivity of the temperate typical steppe in Inner Mongolia. However, under N addition, P addition can promote ANPP and alter the community composition. These findings provide valuable information for the management of the temperate typical steppe.

Nitrogen Addition Affects Ecosystem Carbon Exchange by Regulating Plant Community Assembly and Altering Soil Properties in an Alpine Meadow on the Qinghai-Tibetan Plateau.

Nitrogen (N) deposition can affect the global ecosystem carbon balance. However, how plant community assembly regulates the ecosystem carbon exchange in response to the N deposition remains largely unclear, especially in alpine meadows. In this study, we conducted a manipulative experiment to examine the impacts of N (ammonium nitrate) addition on ecosystem carbon dioxide (CO2) exchange by changing the plant community assembly and soil properties at an alpine meadow site on the Qinghai–Tibetan Plateau from 2014 to 2018. The N-addition treatments were N0, N7, N20, and N40 (0, 7, 20, and 40 kg N ha–1year–1) during the plant growing season. The net ecosystem CO2 exchange (NEE), gross ecosystem productivity (GEP), and ecosystem respiration (ER) were measured by a static chamber method. Our results showed that the growing-season NEE, ER and GEP increased gradually over time with increasing N-addition rates. On average, the NEE increased significantly by 55.6 and 65.2% in N20 and N40, respectively (p < 0.05). Nitrogen addition also increased forage grass biomass (GB, including sedge and Gramineae) by 74.3 and 122.9% and forb biomass (FB) by 73.4 and 51.4% in N20 and N40, respectively (p < 0.05). There were positive correlations between CO2 fluxes (NEE and GEP) and GB (p < 0.01), and the ER was positively correlated with functional group biomass (GB and FB) and soil available N content (NO3––N and NH4+–N) (p < 0.01). The N-induced shift in the plant community assembly was primarily responsible for the increase in NEE. The increase in GB mainly contributed to the N stimulation of NEE, and FB and the soil available N content had positive effects on ER in response to N addition. Our results highlight that the plant community assembly is critical in regulating the ecosystem carbon exchange response to the N deposition in alpine ecosystems.

Short-Term Vegetation Response to Bulldozed Fire Lines in Northern Great Plains Grasslands

A bulldozed fire line is a fire-suppression technique that limits fire movement by altering fuel continuity through vegetation removal and mineral soil exposure. The ecological impacts of a bulldozed fire line may exceed the effects of the fire itself through lasting changes in the soil and vegetation properties; however, little research has been performed to quantify these impacts in grassland systems. In this study, we compared vegetation properties among burned, unburned, and bulldozed fire line conditions on two August 2012 grassland wildfires in Montana. Standing biomass, by growth form, was quantified in 2013 and 2014, and compared using a generalized linear model. Perennial grass production was significantly reduced, while annual grass and annual forb biomass increased in response to the fire line treatment. Shrub and total vegetation standing crop were reduced in response to the fire line in 2013; however, the treatment effects were diminished by 2014. The burned and unburned treatments were generally similar within two years post-fire. The loss of perennial grasses and invasion of competitive annual grasses such as cheatgrass (Bromus tectorum L.) may limit the vegetation recovery of the fire line and promote further invasion of annual grasses into these systems. The marginal impact of the fires on these plant communities suggests the need to limit the use of ad hoc bulldozed fire lines as a suppression activity. If a bulldozed fire line is constructed, we suggest limiting soil disturbance by restricting blade depth to remove only surface vegetation and restricting bulldozer use to flat slopes, even if working with the contour, and incorporating re-seeding as part of or immediately after fire line construction.

Mapping tundra ecosystem plant functional type cover, height and aboveground biomass in Alaska and northwest Canada using unmanned aerial vehicles

Arctic vegetation communities are rapidly changing with climate warming, which impacts wildlife, carbon cycling and climate feedbacks. Accurately monitoring vegetation change is thus crucial, but scale mismatches between field and satellite-based monitoring cause challenges. Remote sensing from unmanned aerial vehicles (UAVs) has emerged as a bridge between field data and satellite-based mapping. We assess the viability of using high resolution UAV imagery and UAV-derived Structure from Motion (SfM) to predict cover, height and aboveground biomass (henceforth biomass) of Arctic plant functional types (PFTs) across a range of vegetation community types. We classified imagery by PFT, estimated cover and height, and modeled biomass from UAV-derived volume estimates. Predicted values were compared to field estimates to assess results. Cover was estimated with root-mean-square error (RMSE) 6.29-14.2% and height was estimated with RMSE 3.29-10.5 cm, depending on the PFT. Total aboveground biomass was predicted with RMSE 220.5 g m&lt;sup&gt;-2&lt;/sup&gt;, and per-PFT RMSE ranged from 17.14-164.3 g m&lt;sup&gt;-2&lt;/sup&gt;. Deciduous and evergreen shrub biomass was predicted most accurately, followed by lichen, graminoid, and forb biomass. Our results demonstrate the effectiveness of using UAVs to map PFT biomass, which provides a link towards improved mapping of PFTs across large areas using earth observation satellite imagery.

Foliar herbivory on plants creates soil legacy effects that impact future insect herbivore growth via changes in plant community biomass allocation

ABSTRACT Plants leave legacy effects in the soil they grow in, which can drive important vegetation processes, including productivity, community dynamics and species turnover. Plants at the same time also face continuous pressure posed by insect herbivores. Given the intimate interactions between plants and herbivores in ecosystems, plant identity and herbivory are likely to interactively shape soil legacies. However, the mechanisms that drive such legacy effects on future generations of plants and associated herbivores are little known. In a greenhouse study, we exposed 10 common grasses and non‐leguminous forbs individually to insect herbivory by two closely related noctuid caterpillars, Mamestra brassicae and Trichoplusia ni (Lepidoptera: Noctuidae) or kept them free of herbivores. We then used the soil legacies created by these plant individuals to grow a plant community composed of all 10 plant species in each soil and exposed these plant communities to M. brassicae. We measured conditioning plant biomass, soil respiration and chemistry of the conditioned soils, as well as individual plant, plant community and herbivore biomass responses. At the end of the conditioning phase, soils with herbivore legacies had higher soil respiration, but only significantly so for M. brassicae. Herbivore legacies had minimal impacts on community productivity. However, path models reveal that herbivore‐induced soil legacies affected responding herbivores through changes in plant community shoot: root ratios. Soil legacy effect patterns differed between functional groups. We found strong plant species and functional group‐specific effects on soil respiration parameters, which in turn led to plant community shifts in grass: forb biomass ratios. Soil legacies were negative for the growth of plants of the same functional group. Synthesis. We show that insect herbivory, plant species and their functional groups, all incur soil microbial responses that lead to subtle (herbivory) or strong (plants and their functional group) effects in response plant communities and associated polyphagous herbivores. Hence, even though typically ignored, our study emphasizes that legacies of previous insect herbivory in the soil can influence current soil–plant–insect community interactions. A free Plain Language Summary can be found within the Supporting Information of this article.

Soil calcium content as the driving factor for vegetative structure and soil microbial function diverging across a fire chronosequence of the boreal forests in northeast China

AbstractThe role of biophysical variables in constructing community structure changes with the time since fire. The major objective of this study is to verify the transition stage and its underlying variables for the postfire forest and soil microbial function in the boreal forested area of China. A 50-year fire chronosequence was presented, and biomass of forbs, shrubs and woody plants was separately weighted to assess their contribution to the whole community with the year since fire (YSF). Simultaneously, soil biophysical properties were measured for stands in different time periods after fire. Soil microbial functions, i.e. growth efficiency (GE) and carbon use efficiency (CUE), were calculated based on ecoenzymatic and soil nutrient stoichiometry. In terms of vegetative structure, forbs’ proportion decreased from 75% to 1.5%, but the proportion of woody plants increased from 0.04% to 70% across this fire chronosequence. GE and CUE of soil microorganisms averaged 0.242 and 0.236 and were significantly higher in 9, 15 and 31 YSF than in 2 and 3 YSF. Soil metal content was significantly increased at the late stage of this fire chronosequence, and soil calcium content showed a positive correlation with woody plant biomass and a negative correlation with soil microbial function. Overall, the present work highlights that the time period of 15 and 31 YSF is a hallmark stage for aboveground vegetative structure and soil microbial function to change in different trends and that the calcium content may partly account for these two divergent trajectories.

Tree invasion in secondary grasslands diminishes herbaceous biomass and diversity: A study of mechanisms behind the process

AbstractQuestionsHow is plant biomass, composition and diversity in secondary grasslands affected by tree invasion? How do light conditions generated by invasive trees and soil legacy affect grassland's structure and functioning? Which mechanism is more important?LocationInland Pampa, Buenos Aires, Argentina.MethodsWe established a long‐term manipulative reciprocal transplant experiment by transplanting soil monoliths coming from two origins: grasslands (G) and invaded woody patches (W) into three different habitats: open grasslands (OG), woody patches (WP), and artificially shaded grasslands (SG).ResultsSeven years after the beginning of the experiment, litter, above‐ and below‐ground herbaceous biomass decreased from OG to WP habitats, with SG habitats showing intermediate values. However, differences between OG and WP habitats disappeared when tree (coarse) roots, and tree litter biomass were considered. No significant differences between the origin of the soil monoliths (G or W) were detected (p &gt; 0.10), except for herbaceous roots biomass that, contrary to expectations, was higher in all habitats when the transplanted soil monoliths came from a W origin. Additionally, biomass of C3 grasses was higher in WP habitats and biomass of C4 grasses was higher in OG habitats, while biomass of forbs had the highest biomass in SG habitats. The inverse Simpson's index decreased from OG (2.08), through SG (1.73) to WP habitats (1.14), suggesting higher dominance in WP.ConclusionsOur study helps to glimpse the main mechanism driving community changes after tree invasions in temperate grassland communities. We demonstrated that light reduction beneath the tree canopies has a more important role than soil legacy in determining structure and functioning of grasslands, even though invasion of Gleditsia triacanthos also affected soil properties such as water content and organic carbon.

Neutral responses of plant community Ca concentration to nitrogen enrichment in a semiarid grassland

AbstractCalcium (Ca) is an essential nutrient for plant growth and Ca concentrations in forage have important implications for ruminant diet and health. It remains an open question whether forage Ca concentration would be decreased by increasing nitrogen (N) deposition. We manipulated the increasing rates of N addition (2008–2015) in a semiarid grassland, northern China. Plant Ca concentrations for all species were examined in each plot under N treatment. The Ca concentrations at functional group and community levels were calculated based on the concentration of each species presented and their relative biomass in each plot. We found that community-level Ca concentration remained stable across a gradient of wide-ranged N addition rates, although Ca concentration at both species and functional group levels showed negative responses to N enrichment. Given that forbs had higher Ca concentration than grasses, the increasing relative biomass of forbs canceled out the negative responses of species-level and functional group-level Ca concentration. Our results further showed that community Ca pool showed a positive but saturating response to N addition, with a threshold at the rate of 10 g N m−2 yr−1. Our findings highlight the role of changes in plant relative biomass in controlling the responses of forage Ca concentration and stock to N enrichment.

Divergent climate change effects on widespread dryland plant communities driven by climatic and ecohydrological gradients.

Plant community response to climate change will be influenced by individual plant responses that emerge from competition for limiting resources that fluctuate through time and vary across space. Projecting these responses requires an approach that integrates environmental conditions and species interactions that result from future climatic variability. Dryland plant communities are being substantially affected by climate change because their structure and function are closely tied to precipitation and temperature, yet impacts vary substantially due to environmental heterogeneity, especially in topographically complex regions. Here, we quantified the effects of climate change on big sagebrush (Artemisia tridentata Nutt.) plant communities that span 76million ha in the western United States. We used an individual-based plant simulation model that represents intra- and inter-specific competition for water availability, which is represented by a process-based soil water balance model. For dominant plant functional types, we quantified changes in biomass and characterized agreement among 52 future climate scenarios. We then used a multivariate matching algorithm to generate fine-scale interpolated surfaces of functional type biomass for our study area. Results suggest geographically divergent responses of big sagebrush to climate change (changes in biomass of -20% to +27%), declines in perennial C3 grass and perennial forb biomass in most sites, and widespread, consistent, and sometimes large increases in perennial C4 grasses. The largest declines in big sagebrush, perennial C3 grass and perennial forb biomass were simulated in warm, dry sites. In contrast, we simulated no change or increases in functional type biomass in cold, moist sites. There was high agreement among climate scenarios on climate change impacts to functional type biomass, except for big sagebrush. Collectively, these results suggest divergent responses to warming in moisture-limited versus temperature-limited sites and potential shifts in the relative importance of some of the dominant functional types that result from competition for limiting resources.

Short-term nitrogen and phosphorus additions rather than mycorrhizal suppression determine plant community composition and productivity in desert steppe

Anthropogenic enrichment of soil nitrogen (N) and phosphorous (P) has dramatically altered ecosystem structures and functions. However, our understanding of the interactions between soil nutrient enrichment and arbuscular mycorrhizal (AM) fungi with plant community performance remains elusive. We examined the impacts of soil N and P enrichment and mycorrhizal suppression on plant community composition and productivity in desert steppe. Our results showed that short-term addition of P alone and combined N and P had stronger influence on plant community composition and productivity, but the addition of N alone had a minimal effect. Individual and combined addition of N and P mainly altered plant community productivity by increasing the biomass of annual forbs, but decreasing that of perennial forbs and C3 grasses, regardless of AM fungi. AM fungal suppression did not alter plant community composition and productivity. Addition of P alone and combined N and P slightly increased plant species richness and diversity. Our findings highlight that the short-term N and P enrichments, rather than the presence of AM fungi, change plant community dynamics in desert steppe.

The Effects of Continuous and Rotational Livestock Grazing on Forb Quality and Quantity: Implications for Pronghorn Habitat Management

Pronghorn (Antilocapra americana) evolved in grasslands with a diet composed of highly nutritious forbs. However, pronghorn habitat throughout North America has been lost to fragmentation and degradation. Additionally, the effects different cattle grazing regimes have on forb biomass, protein, and energy production for pronghorn are not well known in West Texas. We sampled forbs during the growing season in the months of September 2018 and 2019 to assess the effects of different cattle grazing regimes on forbs. We hypothesized rotational grazing would increase the nutritional quality of the forb community and overall forb production, compared to continuous grazing and no grazing. We randomly sampled pastures subject to continuous and rotational grazing, as well as ungrazed exclosures using 100, 96, and 64 1 m2 plots, respectively. We collected all forbs in each plot and analyzed differences in nutritional composition and biomass production using redundancy analysis. We found that the effects of grazing varied by year. In wetter conditions, rotational grazing exhibited higher forb quality and biomass, while exclusion from grazing exhibited these results under drier conditions. The knowledge gained from this study helps resource professionals and landowners understand how cattle grazing affects forbs for pronghorn. This knowledge may be used to improve the suitability of pronghorn habitat through cattle grazing regimes.

Fertilized graminoids intensify negative drought effects on grassland productivity.

Droughts can strongly affect grassland productivity and biodiversity, but responses differ widely. Nutrient availability may be a critical factor explaining this variation, but is often ignored in analyses of drought responses. Here, we used a standardized nutrient addition experiment covering 10 European grasslands to test if full-factorial nitrogen, phosphorus, and potassium addition affected plant community responses to inter-annual variation in drought stress and to the extreme summer drought of 2018 in Europe. We found that nutrient addition amplified detrimental drought effects on community aboveground biomass production. Drought effects also differed between functional groups, with a negative effect on graminoid but not forb biomass production. Our results imply that eutrophication in grasslands, which promotes dominance of drought-sensitive graminoids over forbs, amplifies detrimental drought effects. In terms of climate change adaptation, agricultural management would benefit from taking into account differential drought impacts on fertilized versus unfertilized grasslands, which differ in ecosystem services they provide to society.

Spatial Modeling of Forage Crops for Tiger Prey Species in the Area Surrounding Highway 304 in the Dong Phayayen-Khao Yai Forest Complex

Spatial modeling is an analytical procedure that simulates real-world conditions using remote sensing and geographic information systems. The field data in this study were collected from 318 survey plots in the area surrounding highway 304 in the Dong Phayayen-Khao Yai Forest Complex (DPKY-FC) during the 2019 rainy season. Forage-crop biomass was collected from all plots. We focused on sambar deer (Rusa unicolor) and gaur (Bos gaurus), which are the main prey for tigers in this area. We created spatial models using generalized linear models with stepwise regression. The results indicated that the normalized difference vegetation index (NDVI) varied directly with grass biomass but inversely with shrub biomass (p&lt;0.05). Elevation varied directly with forb biomass but inversely with shrub biomass (p&lt;0.05). The probability of occurrence of sambar deer varied directly with distance from disturbance variables, distance from the stream, and grass biomass (p&lt;0.001), but inversely with NDVI (p&lt;0.05). The occurrence of gaur varied directly with NDVI (p=0.08), but varied inversely with slope, distance from the road, and distance from the stream (p&lt;0.05). Our results demonstrate that spatial modeling can be an effective tool for wildlife habitat management in the area surrounding highway 304.

Size‐selective exclusion of mammals and invertebrates differently affects grassland plant communities depending on vegetation type

Abstract Human‐caused loss of vertebrate and invertebrate animals, defaunation, is increasing, and potentially affects plant community structure of diverse grassland ecosystems world‐wide. We experimentally simulated defaunation using size‐selective fences to progressively exclude large‐, medium‐ and small‐sized mammals, and invertebrates from two subalpine vegetation types in the Swiss National Park (SNP): intensively grazed short‐grass and moderately grazed tall‐grass vegetation. We assessed plant community properties yearly from 2009 to 2013, and examined treatment effects on plant community structure in the two grassland types. In the short‐grass vegetation, the exclusion of large mammals increased total plant biomass, while the exclusion of large and medium‐sized mammals increased total, grass and forb biomass compared to when all animals had access. These increases became stronger when invertebrates were also excluded. The exclusion of all mammals and invertebrates increased biomass of grasses by 205%, forbs by 100% and total plant biomass by 118% compared to when all animals had access, hence enhancing relative biomass of grasses from 43.6% to 60%, changing plant species composition and lowering richness of forbs by 16%, the number of plant families by 13% and family‐level Shannon diversity by 23%. In contrast to these significant community‐level responses found in the short‐grass vegetation, there was no evidence that the size‐selective exclusion of animals altered the plant community structure of the tall‐grass vegetation. The contrasting results were due to the difference in plant community composition prior to our experiment, which were related to differences in quantity and quality of forage and in grazing intensities of herbivores between the two grassland types. Synthesis. Our results showed that different‐sized animals, in particular large mammals and invertebrates, contributed to maintain the plant community structure in the short‐grass vegetation, highlighting the importance of multiple, functionally different animal groups for ecosystem functioning and stability. In contrast to the short‐grass vegetation, we could not detect such a top‐down control by animals in the tall‐grass vegetation. Our results suggest that potential defaunation effects on grassland plant community structure depend on the degree of grazing pressure release and grassland vegetation type.

Effect of 15‐year sward management on vertical distribution of plant functional groups in a semi‐natural perennial grassland of central Europe

AbstractAimsThe nutrient concentration in herbage and biomass productivity analyses are dependent on the vertical distribution of different sward layers where the sampling is done. Notably, a majority of studies indicate clipping biomass to the ground level without any consideration of the vertical distribution. This study examined the effect of cutting and grazing intensities on the vertical distribution of plant functional groups.LocationOldřichov Grazing Experiment, northern Czechia.MethodsDuring a 15‐year experiment: (a) intensive and (b) extensive grazing without cutting; (c) cutting in June followed by intensive and (d) extensive grazing; and (e) undefoliated treatment were applied throughout the vegetation season. Biomass data were collected at two layers in the sward (below and above 3 cm) and separated into five functional groups. Biomass data were analysed to examine the succession and effects of treatments on vertical distribution of functional groups.ResultsTreatment effects were differentiated after 2–3 years from the introduction of management, but the composition of functional groups fluctuated over time. Treatments significantly affected total biomass of all functional groups and the vertical distribution within swards of most groups. Particularly intensive grazing significantly decreased the total biomass of graminoids, forbs, and dead biomass in favour of legumes (which increased). This led to a shift in the relative biomass distribution from the upper sward layer to the lower layer for most functional groups except for legumes and mosses.ConclusionThe high proportion of dead biomass in the lower sward layer suggests the need for a methodological approach that considers clipping of biomass only above 3 cm when sampling for productivity and forage quality analysis. This approach would avoid including biomass from below 3 cm or the lower layer, which would be ungrazed by cattle. Many previous studies may have reported a distorted or inflated value in herbage productivity or forage quality results.

Effects of Soil Nutrient Heterogeneity and Earthworms on Aboveground Biomass of Experimental Plant Communities

Soil nutrients are commonly heterogeneously distributed and earthworms are one of the most common soil organisms. While effects of both soil nutrient heterogeneity and earthworms have been well studied, their interactive effect on plant community productivity has rarely been tested. In a greenhouse experiment, we constructed experimental plant communities by sowing seed mixtures of four grasses, two legumes and two forbs in either a heterogeneous soil consisting of low and high nutrient soil patches or a homogeneous soil where the low and high nutrient soil patches were evenly mixed. The earthworm <i>Eisenia fetida</i> was either added to these soils or not. Aboveground biomass of the whole communities, grasses and legumes did not differ between the homogeneous and heterogeneous soils or between the soils with and without earthworms. However, soil nutrient heterogeneity reduced aboveground biomass of forbs, and such an effect did not interact with earthworms. In response to soil heterogeneity and earthworms, biomass ratio of the three functional groups showed similar patterns as that of their biomass. At the patch level, aboveground biomass of the whole community, grasses and legumes were greater in the high than in the low nutrient soil patches within the heterogeneous soil. A similar pattern was found for the forbs, but this was only true in the absence of earthworms. Our results suggest that soil nutrient heterogeneity and earthworms may not influence aboveground biomass of plant communities, despite the fact that they may modify the growth of certain plant functional groups within the community.

Vacant lot soil degradation and mowing frequency shape communities of belowground invertebrates and urban spontaneous vegetation

Vacant land in legacy cities is increasingly recognized as a resource to support biodiversity and improve the quality of life for residents. However, the capacity for vacant lot parcels to provide these benefits is influenced by current management practices and landscape legacies of urbanization, which typically results in degraded soil quality. The role of soil quality in supporting urban biodiversity and ecosystem functions is often overlooked when developing sustainable urban planning initiatives. This study investigated how soil physical and chemical properties influenced the community of urban spontaneous vegetation and soil invertebrates found within vacant lots mowed monthly or annually in Cleveland, Ohio, USA. We found that soil chemical and physical properties were strong predictors of soil-dwelling invertebrates, as vacant lots highly contaminated with heavy metals had simplified communities. Moreover, increased mowing frequency resulted in greater biomass and blooms of urban spontaneous forbs. Importantly, vacant lots dominated by urban spontaneous forbs and high bloom abundances also were contaminated with heavy metals, with implications for herbivores and pollinators using these resources. Our findings indicate that conservation initiatives must consider landscape legacies from industrial activity and local habitat management practices in order to support above and belowground habitat quality of greenspaces in urban ecosystems. Understanding how soil degradation impacts habitat quality and the delivery of ecosystem services from vacant land is essential for legacy cities to maximize their environmental benefits.