Forb Species Research Articles

Effects of Fire on Diversity and Aboveground Biomass of Understory Communities in Seasonally Dry Tropical Forest in Western Thailand

Fire is a necessary disturbance in tropical deciduous forests, as it helps clear the understory community and allows regeneration of grasses and forbs for local wildlife. Huai Kha Khaeng Wildlife Sanctuary (HKK) and Huai Thab Salao-Huai Rabum Non-Hunting Area (HTS) are parts of a few places in Southeast Asia with deciduous forests. However, this area was heavily logged up until 1989, followed by a long period of fire suppression. The consequences of these changes on understory communities have not been investigated. Therefore, the current study aimed to examine the understory communities and their aboveground biomass before and after the annual prescribed burns in HKK and HTS. Understory plant composition and biomass were surveyed in November 2018 (before the fire) and May 2019 (three months after the fire) in 128 temporary plots, covering of deciduous dipterocarp forest, mixed deciduous forest, mixed deciduous forest with bamboo, and open area. We identified a total of 480 understory species, including 37 grass species, 214 forb species, 73 shrub species, 153 tree seedling species and three species of bamboo in the study plots. Grasses in the DDF plots were at 72.79 ± 22.41 kg ha−1, accounting for only ten percent of the understory plants in the plots. The understory community in the DDF plots was dominated by shrubs and tree seedlings of competing species, especially after the fire. The results suggested that past logging activities and long-term fire suppression had reduced the number of mature key dipterocarp forests and hindered the regeneration of grasses and forbs. Maintaining the structure of dipterocarp forests and sufficient food sources for the local wildlife species will require more active habitat management of the study areas.

Above‐ and below‐ground responses to experimental climate forcing in two forb species from montane wooded pastures in Switzerland

Abstract Mountain ecosystems are particularly threatened by ongoing climate change and the species composition of high elevation grasslands is already changing. An open research question is how these ecosystems will adapt to changes in their key environmental constraints. The responses of wooded pastures to experimental climate forcing were analysed in a transplantation experiment conducted downslope, along an elevational temperature and precipitation gradient on the lee side of Jura Mountains, Switzerland (up to +4.17°C and −35% precipitation). To improve mechanistic understanding of biodiversity and biomass decreases in response to transplantation, changes in functional traits within foliage and roots of one ubiquitous (Taraxacum officinale) and one montane (Alchemilla monticola) perennial forb species were investigated. In consequence of transplantation, the two studied species raised their temperature optimum for CO2 assimilation and net photosynthesis yield from 20 to 30°C. During cool periods, the highest rates of leaf gas exchanges were measured at the lower recipient sites. However, an opposite trend was observed during a spring drought and summer warm spell. Regarding the more integrative morpho‐anatomical traits, Alchemilla primarily acclimated to warmer temperatures at the recipient sites with increased leaf and foliage rosette size. Missing xeromorphic and/or hydraulic adjustments in foliage and roots, its susceptibility to higher vapour pressure deficits and lower soil moisture availability was thus enhanced. Taraxacum showed adjustments to both warmer temperature and lower moisture availability, including reduced leaf size, lower hydraulic diameter of xylem vessels and theoretical specific hydraulic conductivity. The anticipated shift in the environmental conditions at high elevation, with reduced coldness limitation but increasingly constraining water economy, could thus become particularly demanding for montane species of wooded pastures. It may favour perennials with large phenotypic plasticity but leads to maladjustments and loss of the species which are more specifically adapted to montane conditions. Read the free Plain Language Summary for this article on the Journal blog.

Endozoochorous seed dispersal by Korean water deer (Hydropotes inermis argyropus) in Taehwa Research Forest, South Korea

Endozoochorous seed dispersal by ungulates can facilitate the dispersal of seeds over long distances. Endozoochorous seed dispersal can also result in the ecological filtering of plant species by dispersing plant seeds with distinctive traits. The Korean water deer (Hydropotes inermis argyropus) is a potential long-distance seed dispersal vector in lowland areas of South Korea. In this study, to test the endozoochorous seed dispersal role of Korean water deer in forested areas, we collected 202 fresh fecal pellet group samples in Taehwa Research Forest, Gwangju City, Gyeonggi Province, South Korea. Additionally, we conducted a vegetation survey to compare the traits of dispersed seeds from feces with the seed traits of flora in the study site. To test whether the composition of species traits dispersed by endozoochory is consistent with that of lowland areas, which consist of forested hills, arable land, and wetlands, we compared the results with a former study conducted in the lowlands. From the seedling emergence method applied to feces, we found a total of 22 species and 115 seedlings. Among 202 fecal pellet groups, 19.8% had at least one germinable seed. Species of forbs, with small-sized seeds (≤2 mm in length), from open habitat, and seeds without special morphology for dispersal are most frequently dispersed through Korean water deer endozoochory. These traits were consistent with the former endozoochory study conducted in a lowland area, irrespective of the different available flora. Therefore, we suggest that deer can potentially disperse seeds with the aforementioned traits to forest plant communities, acting as a consistent ecological filter through endozoochory.

Deciphering the interactions between plant species and their main fungal root pathogens in mixed grassland communities

Abstract Plant diversity can reduce the risk of plant disease, but positive, and neutral effects have also been reported. These contrasting relationships suggest that plant community composition, rather than diversity per se, affects disease risk. Here, we investigated how the diversity and composition of plant communities drive root‐associated pathogen accumulation belowground. In a temperate grassland biodiversity experiment, containing 16 plant species (forbs and grasses), we determined the abundance of root‐associated fungal pathogens in individual plant species growing in monocultures and in four‐species mixtures through Illumina MiSeq amplicon sequencing. In the plant monocultures, we identified three major fungal pathogens that differed in host range: Paraphoma chrysanthemicola, associated with roots of forb species of the Asteraceae family, Slopeiomyces cylindrosporus, associated with grass species, and Rhizoctonia solani, associated with multiple forb and grass species. In mixtures, there was no significant reduction in relative abundance of these pathogens in their host species as compared to monocultures. However, in mixtures, there was a significant increase in relative abundance of each pathogen in several non‐host and host plant species. Across mixtures, plant community composition affected pathogen relative abundance in individual plant species. This effect was driven by the presence of a particular neighbouring plant species (depending on the pathogen), rather than functional group composition (i.e. grass/forb ratio) or averaged pathogen pressure (based on monocultures) of all neighbours. Specifically, the presence of neighbour host species Achillea millefolium significantly increased P. chrysanthemicola, but decreased R. solani relative abundance in several host and non‐host plant species in mixtures. Synthesis. Our results indicate that interactions between different plant species—both host and non‐hosts—and fungal pathogens underlie the effects of plant diversity on root pathogen abundance. Non‐host species may act as pathogen reservoirs in diverse plant communities, as they harboured certain pathogens in mixtures, but not in monocultures. Additionally, particular host species can strongly affect pathogen abundance in other (host and non‐host) plant species in plant mixtures, suggesting clear effects of species identity in the diversity–disease relationship. Below‐ground disease risk thus depends on plant community composition rather than diversity per se, via specific interactions between plant species and their root‐associated pathogens.

UV radiation and drought interact differently in grass and forb species of a mountain grassland

Among abiotic stressors, drought and enhanced ultraviolet radiation (UV) received a lot of attention, because of their potential to impair plant growth. Since drought and UV induce partially similar protective mechanisms, we tested the hypothesis that UV ameliorates the effect of reduced water availability (WA) in selected grass (Holcus mollis and Agrostis capillaris) and forb species (Hypericum maculatum and Rumex acetosa). During 2011–2014, an outdoor manipulation experiment was conducted on a mountain grassland ecosystem (Beskydy Mts; Czech Republic). Lamellar shelters were used to pass (WAamb) or exclude (WA–) incident precipitation in order to simulate reduced water availability (WA). In addition, the lamellas were made from acrylics either transmitting (UVamb) or blocking (UV–) incident UV. Generally, both UV exposure and reduced WA enhanced epidermal UV-screening, while exposure to both factors resulted in less than additive interactions. Although UV radiation increased epidermal UV-screening rather in the grass (up to 29 % in A. capillaris) than forb (up to 12 % in H. maculatum) species and rather in well-watered than reduced WA plants, such acclimation response did not result in significant alleviation of reduced WA effects on gas exchange and morphological parameters. The study contributes to a better understanding of plant responses to complex environmental conditions and will help for successful modelling forecasts of future climate change impacts.

Traffic patterns, more than adjacent land use, influence element content of roadside forbs for insect pollinators

Abstract Roadsides are targeted for restoration of pollinator‐friendly plants. Yet, roads are sources of macronutrient, micronutrient and heavy metal pollution that may contaminate roadside plants. Adjacent landscape features such as railroads and agriculture provide additional macronutrient and heavy metal pollution that may exacerbate traffic effects. However, we lack perspective on how roads combine with rural landscape features to influence nutrition of roadside plants, which could have implications for pollinator health. We surveyed roadsides across Minnesota, USA and measured foliar levels of dietary macronutrients (nitrogen, phosphorous and potassium), a micronutrient (sodium) and metals (iron, zinc, copper, chromium, nickel, lead, aluminium and cadmium) in six abundant roadside forb species used by insect pollinators: Asclepias syriaca, Dalea purpurea, Monarda fistulosa, Ratibida pinnata, Solidago spp. and Trifolium pratense. We aimed to determine (1) how road variables (traffic volume and distance from road) combine with adjacent land use (railroad and agriculture) to influence element content of roadside forbs and (2) whether some forb species show consistent differences in their accumulation of potentially toxic heavy metals, which could inform selection of species to plant along roadsides. We found that foliar concentrations of nine elements increased with greater traffic volume (nitrogen, phosphorous, iron, zinc, copper, chromium, nickel, lead and aluminium), and concentrations of six elements declined with distance from the road (nitrogen, phosphorous, potassium, iron, zinc and copper). Leaves collected adjacent to railroad had less phosphorous, potassium, iron, nickel and aluminium than leaves collected from sites not adjacent to railroad. Additionally, leaves collected from sites adjacent to agriculture had lower copper levels than leaves from sites without adjacent agriculture. We found no evidence that particular ford species along roadsides consistently rank higher than other species in their accumulation of heavy metals. Our results show that traffic alters more elements in roadside plants than does adjacent landscape context, alleviating concerns that landscape features exacerbate pollutant levels in roadside pollinator habitat. However, nutrient contamination of most roadside plants is unlikely to reach toxic levels for insect pollinators. This work is consistent with the positive conservation potential of low to moderate traffic roadsides for pollinators.

Can pasture‐fed livestock farming practices improve the ecological condition of grassland in Great Britain?

Abstract Livestock farming in Great Britain (GB) faces multiple pressures. Yet, grassland managed for livestock is the most extensive habitat in GB and is key to cultural landscapes and their biodiversity and soil health. This study analysed a nationally representative dataset of over 940 large (200 m2) Neutral (agriculturally semi‐improved) and (agriculturally) Improved Grassland plots from the GB Countryside Survey (CS) to assess relationships between key grassland sward and soil variables. Analysis also looked at how these variables changed over time as plots switched between these grassland types. Data from grassland plots managed by Pasture‐Fed Livestock Association (PFLA) farmers were compared to CS plot data to assess the impacts of their practices on these variables. Plant species richness in Neutral grassland types in CS plots was positively associated with total soil invertebrate abundance (total taxa) and soil N and C and negatively associated with soil P. There were negative relationships between the covers of Lolium sp. (Neutral only), legumes and forbs and soil C and moisture variables. Grassland swards on PFLA member farms were characteristic of Neutral grassland. PFLA plots were more species rich and contained more legume and forb species and lower proportions of Lolium perenne than those on Improved Grassland. Vegetation height was greater in PFLA plots than in CS plots of either Improved or Neutral Grassland. Unlike CS Neutral Grassland plots, soil properties in PFLA plots were not significantly different from those for Improved Grassland for any measured variable (soil carbon concentration [C], bulk density, pH, nitrogen [N], phosphorus [P]). Higher species richness in grasslands is associated with positive measures of soil health. PFLA plant communities contain relatively high species richness and tall vegetation, which is positive for biodiversity. Lack of positive measures of soil health associated with higher species richness recorded in PFLA grassland (as opposed to CS grassland) may reflect time lags in soil responses to management, as evidenced through an analysis of the impacts of land‐use change over time on CS plot characteristics. Our findings indicate that pasture‐fed livestock approaches may be beneficial for grassland and wider ecosystems.

Bison wallows effect on soil properties, vegetation composition and structure in a recently reintroduced area

Bison are considered an ecologically keystone species of the North American grasslands because their activities influence ecosystem dynamics and interactions, particularly their wallowing behavior. In 2009, 23 bison were reintroduced within a 1,500 ha private native semi-arid grassland in Janos, Chihuahua. Our objective was to evaluate the effect of bison wallows on the composition and structure of the vegetation, on species composition of annual grasses, and soil properties. Soil and vegetation samples were taken from inside the wallows and were compared against the samples obtained outside the wallows from late August to early September. The percentage of plant cover and the height of the foliage were measured inside and outside the wallow. Soil cores were taken, and the presence of soluble salts, moisture retention capacity, percentage of clay, and concentration of nutrients was determined. The three associations preferred by bison for wallowing were toboso grassland, vine mesquite and annual grassland. Of the 27 species of grasses and forbs recorded in the three plant associations mostly used for wallowing, we found that 17 species were present inside and outside wallows. Five different species were found only inside wallows and another five, only outside of wallows. The annual grassland plants had a greater height outside the wallows. The toboso grassland association presented higher soil moisture, likely related to the higher percentage of clay, and the annual grassland presented the highest bulk density (BD) inside the wallows, which limited plant growth in this association. Soils in other associations did not show significant differences in BD among them, mainly due to their finer texture. No significant effect of the wallows on nutrient concentrations was recorded. The lack of significant differences related to bison activities could be related to the brief period since the herd was reintroduced to the site. These differences might become apparent over time with a larger herd. For this reason, we conclude that the current differences in the soil properties are mainly due to geomorphological processes. That is, at this stage after the reintroduction, the grasslands are responding to soil characteristics, and not to the activity of the bison.

194 Sustainable Livestock Production from Phytochemically Diversified Pastures

Abstract Agricultural systems must increase productivity while conserving the natural resource base and optimizing ecosystem services to meet the converging challenges posed by a growing human population, increasing costs of production inputs, and widespread environmental degradation. Thus, sustainability concerns justify the needs for readjustment of pasture strategies and redefining the role of forages in livestock production. The function of forages in pasture-based livestock systems needs to be broaden beyond their agronomic and animal nutrition benefits. Specifically, the potential of bioactive compounds found in forb species in reducing greenhouse gas (GHG) emissions, boosting animal immune system, increasing the biochemical richness of animal products and ecosystem benefits should be considered in designing pasture systems. It is key to take full advantage of the benefits provided by the biochemicals present in diverse arrays of forages, as they can contribute to the enhancement of feed efficiency and animal health at relatively low costs to the producer. The use of phytochemically diverse pastures that include legumes and forbs with high nutritive quality together with the presence of beneficial plant secondary compounds can improve the antioxidant capacity and the immune function of livestock and reduce animal CH4 emissions and nitrate (NO3) leaching from soils. The main tenet of the invited talk will be to provide information on recent research findings on the effects of temperate forb species with high bioactive compounds on animal production, health and GHG emissions. Furthermore, how these forages can be successfully incorporated in pasture systems and animal feeding programs in temperate agro-ecologies will be discussed.

Effects of N and P enrichment on plant photosynthetic traits in alpine steppe of the Qinghai-Tibetan Plateau

BackgroundN (nitrogen) and P (phosphorus) play important roles in plant growth and fitness, and both are the most important limiting factors that affect grassland structure and function. However, we still know little about plant physiological responses to N and P enrichment in alpine grassland of the Qinghai-Tibetan Plateau. In our experiment, five dominant common herbaceous species were selected and their photosynthetic parameters, leaf N content, and aboveground biomass were measured.ResultsWe found that species-specific responses to N and P enrichment were obvious at individual level. N addition (72 kg Nha−1 yr−1), P addition (36 kg Pha−1 yr−1) and NP addition (72 kg Nha−1 yr−1and 36 kg P ha−1 yr−1, simultaneously) significantly promoted net photosynthetic rate of Leymus secalinus. Differential responses also existed in the same functional groups. Responses of forb species to the nutrients addition varied, Aconitum carmichaeli was more sensitive to nutrients addition including N addition (72 kg Nha−1 yr−1), P addition (36 kg Pha−1 yr−1) and NP addition (72 kg Nha−1 yr−1and 36 kg P ha−1 yr−1). Responses of plant community photosynthetic traits were not so sensitive as those of plant individuals under N and P enrichment.ConclusionsOur findings highlighted that photosynthetic responses of alpine plants to N and P enrichment were species-specific. Grass species Leymus secalinus had a higher competitive advantage compared with other species under nutrient enrichment. Additionally, soil pH variation and nutrients imbalance induced by N and P enrichment is the main cause that affect photosynthetic traits of plant in alpine steppe of the Qinghai-Tibetan Plateau.

Effects of Native and Non-Native Invasive Grasses on Northern Bobwhite Habitat in South Texas

Usable space for northern bobwhite (Colinus virginianus) has been reduced across South Texas rangelands because of the spread of non-native, invasive grasses. A native grass, tanglehead (Heteropogon contortus), has also rapidly expanded its dominance in South Texas within the past 25 yr. It has formed high-density monocultures, similar to non-native grasses, which are associated with losses of herbaceous diversity and bare ground, both key components of bobwhite habitat. The objectives of our research were to 1) determine selection-avoidance of invasive grass cover by bobwhites and 2) determine effects of invasive grass cover on vegetation characteristics.We hypothesized the effects of tanglehead on bobwhite would be negative and similar to the effect of non-native grasses in the region. We recorded covey locations via helicopter surveys in December 2014 and 2015, with field measurements of bobwhite habitat at covey and random locations taken each spring. We measured grass and forb species richness, herbaceous vegetation height, woody-plant cover, tanglehead canopy cover, and non-native grass canopy cover at all covey detections and an equal number of random locations. We developed continuous selection ratios using Simple Saddlepoint Approximations to determine habitat selection by bobwhites. We also used quantile regression, at the 10th, 50th, and 90th quantiles, to determine relationships between invasive grass cover and vegetation factors. Bobwhites avoided areas of high canopy cover (> 20%) of all invasive grasses measured. We found negative relationships between native and non-native invasive grass cover and forb and grass species richness, as well as bare ground, and a positive relationship with herbaceous vegetation height at all quantiles modeled. Our results demonstrate the negative effects of increased tanglehead cover on native rangeland habitats, which aligns with similar non-native invasive grasses. Further expansion by tanglehead has the potential to significantly reduce usable space for bobwhites in South Texas.

Urban Prairie Plots and Gardens Can Sustain Plant-Pollinator Interactions Similar to Established Rural Prairies

Urban prairie “gardens/plots” are gaining popularity for providing similar ecological services as remnant and restored prairies, which are predominantly found in rural areas. However, it is not known to what extent small urban prairies can sustain the plant-pollinator interactions that are vital to both the insects and the plants. The goal of our research was to examine plant/pollinator interactions in three urban prairies in southwest Missouri and compare them to rural managed/restored prairies using a visit-based approach. Urban prairies were all in Springfield, Mo. and shared similar habitat matrices (within an area of 8 km2); rural prairies were located within 68 km of urban prairies, shared similar habitat matrices to each other, and shared soil edaphic characteristics with an urban prairie. From May through August 2018 in all six prairies, we observed the five most abundant forbs in bloom, the number of pollinator visits by bees, butterflies/moths, wasps, beetles, and flies; and, pollinator fidelity from dawn to dusk. The areas observed within a prairie, hereafter “plot(s)”, were determined randomly by where at least two plants of the same species, out of the five most abundant forbs, were located. Using these criteria of observations on the five most abundant species across six prairies and four months, a total of 66 forb species were identified, with 58 of the species native to tallgrass prairies. However, only eight of the 58 native forb species were shared across urban and rural prairies. Jaccard similarity indices indicate lower similarity of the five abundant forbs within urban plots (9%) when compared to rural plots (24%), and low similarity between urban and rural plots (9%). Insect visitation varied by prairie type (rural/urban), month, and insect group; however, urban plots received 61% of the total visits compared to 39% in rural plots. Bees accounted for 5913 visits out of 10,113 visits recorded; high bee visits were similar in urban and rural plots. Insect fidelity was over 97% and did not significantly differ between rural and urban prairies. Therefore, the lack of similarity among and across urban and rural prairies in dominant species did not affect insect visitation rates or fidelity in our study. Our results suggest that establishment and management of urban prairie gardens and plots of various size may sustain the same or greater levels of pollinator services as rural prairies.

Disturbance of plateau zokor (Eospalax baileyi) mounds increase plant and soil macroinvertebrate richness by offering a diversified microenvironment

Habitat heterogeneity is expected to change community composition and diversity, with large implications for ecosystem processes and function. Understanding the potential mechanisms of habitat heterogeneity affecting community ecological processes is a central issue in biodiversity conservation. In this study, we use a spatial metrics analysis to quantify the spatial pattern of plateau zokor mounds. We integrated soil physicochemical variables and community characteristic data to understand the disturbance effect of plateau zokor mounds on community diversity at a microhabitat scale (400 m2). Results showed that plant species richness increased significantly with increasing disturbance levels. Increases in forb species were largely the reason for the increased plant diversity in the alpine meadow disturbed by plateau zokor mounds. Disturbance caused by the plateau zokor significantly increased the soil macroinvertebrate richness and abundance, with herbivorous taxa playing a key role. Mantel tests and redundancy analysis showed that the composition of plant and soil macroinvertebrate communities are significantly related to soil moisture and soil temperature, and the SEM model revealing soil moisture and soil temperature positive effects on plant and macroinvertebrate richness after plateau zokor disturbance. Furthermore, soil variables (moisture, temperature, and organic carbon) directly affected plant richness, and indirectly affected soil macroinvertebrate communities. Our results suggest that the spatial pattern of plateau zokor mounds facilitate greater biodiversity through increased habitat complexity and heterogeneity. Therefore, it can be regarded as a “key species” in the alpine grassland and researchers should pay more attention to the ecological effects of alpine rodent disturbance on grassland ecosystems.

Enclosure in Combination with Mowing Simultaneously Promoted Grassland Biodiversity and Biomass Productivity.

Grassland is the primary land use in China, which has experienced extensive degradation in recent decades due to overexploitation. Here, we conducted field experiments to quantify the degraded grassland’s recovery rate in Northeast Inner Mongolia in response to restoration measures, including fallow + enclosure (FE) and mowing + enclosure (ME) in comparison to livestock grazing (LG), since 2005. Plant community properties were surveyed and aboveground biomass (AGB) sampled in summer 2013. Our results showed that the regional dominant species Leymus chinensis retained its dominance under FE, whereas a range of forb species gained dominance under LG. Vegetative cover was maximal under FE and minimal under LG. The least amount of vegetation development and AGB were observed under LG. However, plant diversity showed an opposite pattern, with maximal diversity under LG and minimal under FE. Statistical analysis revealed that AGB was negatively associated with plant diversity for all treatments except ME. For ME, a positive AGB-diversity relationship was characterized, suggesting that mowing intensity was a controlling factor for the AGB-diversity relationship. Overall, these results demonstrated that enclosure plus mowing represented an effective conservation measure that provided fair support to forage production and a progressive pathway to a more resilient grassland system.

The effect of 19 years of restoration managements on forage quality and herbage‐soil relationships within improved upland grassland

AbstractRestoration managements based on extensification strategies are commonly used to improve biodiversity on formerly improved grasslands. In this study the long‐term effects of six different restoration management regimes (extensive sheep grazing only, hay cutting only, hay cutting followed by aftermath extensive grazing; each with and without lime application) on forage quality, and soil/herbage/sward characteristics relationships were determined and compared with a conventionally fertilized, limed and extensively grazed control.Restoration managements incorporating cutting resulted in higher forage quality than forage from grazed‐only treatments; the latter featuring only a few forb species and large proportion of ungrazed matured grasses plus dead biomass. Concentrations of crude protein, neutral detergent fibre and K in the herbage were negatively correlated with cover of forbs and total number of plant species, whereas in vitro organic matter digestibility, and concentrations of water‐soluble carbohydrates, Ca, Mg, and Na were correlated positively. In contrast, concentrations of Ca, Mg, and Na were negatively correlated with the total cover of graminoids and dry matter standing biomass. Regardless of management treatment the forage was generally suitable only for sheep or beef cattle feeding. A positive relationship between P and K concentration in the soil and in the herbage was recorded. No effect of previous liming on forage quality was found. Overall, this study found introducing long‐term restoration managements to support biodiversity by postponing the timing of the first defoliation by cutting to mid growing season did not deteriorate forage quality in comparison with continual extensive sheep grazing in improved upland grassland.

Can sowing density facilitate a higher level of forb abundance, biomass, and richness in urban, perennial “wildflower” meadows?

Forb species abundance and richness determine both ecological and social values in naturalistic meadows in urban landscapes. However, species loss and dominance through competition are naturally part of meadow ecological processes often leading on productive soils to large grass biomass in the absence of appropriate management. Sowing density is a design tool to manipulate the initial number of emergents of each component species however high sowing densities may not benefit community performance in terms of species richness and diversity in the longer term. This study investigated the effect of sowing density on forb species abundance, biomass and richness. Two sowing densities approximating to 500 and 1,000 emerged seedlings/m2 were employed with 29 forb and one grass species. The higher sowing density did not lead to a larger grass biomass that dominated the community, as the grass species used was ultimately less competitive than the forb dominants. Increasing sowing density increased the number of forb seedlings initially but this declined, as did species richness in the longer term. In terms of subordinate forb survival, ability to access light resources to survive intense competition from dominants was key. Tall, and native species were more likely to maintain higher seedling numbers in the longer term. The research suggest that lower sowing rates are likely to be most useful on soils which are either unproductive, do not contain a significant weed seed banks, where weed free sowing mulches are employed or in rural situations where there is less immediate political pressure for rapid development of forb rich meadows.

Variation in overall fitness due to seed source: projections for predictive provenancing

Seed sourcing decisions affect short‐ and long‐term restoration outcomes. Seeds sourced closer to restoration sites are likely to be better adapted to local conditions and therefore may perform better than those sourced farther away, following assumptions of local adaptation. However, plants may not be adapted to future conditions under climate change; hence, managers are considering a predictive provenancing approach, where plant materials adapted to predicted conditions are used at a site. Currently, there is little empirical evidence available to inform this approach. To address this, we evaluate predictive provenancing using three species of forbs used in tallgrass prairie restorations (Allium cernuum, Chamaecrista fasciculata, and Rudbeckia hirta) in a common garden experiment in northeastern Illinois, U.S.A. We compared the fitness in plants sourced from three regional zones across a latitudinal gradient that represents different climate projections, relative to the planting site. Data were analyzed using Aster life‐history models and generalized linear models. We found that source affected overall fitness in all three species, but no climate proxy had the highest fitness across all species. The performance at each life stage had different effects on overall fitness, which varied by source. We observed later reproductive phenology in southern‐sourced plants for all three species, possibly due to adaptation to longer growing seasons. The mixed results of this study suggest that climate proxy alone would not be sufficient to determine an effective and accurate predictive provenancing strategy. Long‐term tests are needed to pursue such a strategy for high‐priority species.

Phytochemical, antioxidant, and functional group analyses of South African Evolvulus alsinoides (L.) L.

Evolvulus alsinoides (L.) L. (Convolvulaceae) is a forb species that is highly valued in traditional medicine for its memory-enhancing effects, and a range of other ethnomedicinal properties. However, there are no studies on the phytochemical composition and antioxidant activities of E. alsinoides collected in South Africa. The present study was designed to investigate the phytochemical contents and antioxidant properties of aqueous and ethanolic plant extracts of E. alsinoides collected from the Limpopo Province of South Africa. The phytochemical contents were determined using spectrophotometric and colorimetric methods, while the antioxidant activities were determined using three in vitro antioxidant ([2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS), and Ferric reducing antioxidant power (FRAP)] assays. Additionally, the functional groups present in the extracts were analyzed using Fourier-transform infrared (FTIR) spectroscopy. Results revealed that the ethanolic extracts of E. alsinoides gave the highest content of total phenol (17.07 ± 2.28 mg GAE/g DW extract), total flavonoid (82. 44 ± 0.93 mg QE/g DW extract), and proanthocyanidin (32. 98 ± 2.10 mg CE/g DW extract). The total alkaloid and saponin quantification of the crude extract of E. alsinoides gave mean percentage values of 2.6 ± 0.2% and 33.7 ± 0.00%, respectively. The ethanol extract had the highest DPPH scavenging ability (IC50 value: 0.4367 mg/mL), ABTS scavenging ability (IC50 value: 0.099 mg/mL) and the best ferric reducing antioxidant power (138.16 ± 3. 27 mg TE/ g). The total phenolic, flavonoid, and proanthocyanidins contents positively correlated with DPPH and ABTS activities. The spectral data of FTIR analysis of E. alsinoides extracts revealed the presence of functional characteristic groups of carboxylic acids, aromatic amines, alkanes, phenols, alkynes, hydroxy, alcohols, and sulfoxide, which could contribute to the medicinal properties of this plant species. The results of the study justify the usage of E. alsinoides in folkloric medicine and can be explored further for pharmaceutical plant-based products.

Performance of native succulents, forbs, and grasses on an extensive green roof over four years in subtropical Australia

To achieve enduring low-maintenance green roofs that provide maximum benefit in the subtropics, plants need to be well adapted to the local climate with extensive green coverage. The use of native plants contributes to ecological restoration, yet there is very limited information available on their performance in the subtropics. This study aimed to determine the performance of nine species of Australian native forbs, succulents, and grasses in monofunctional and functionally-mixed plant communities on an extensive green roof in Brisbane over four years. Green coverage and survival were monitored via image analysis and observational visits. Forbs established slowly, but successfully (82 % green coverage, 67 % survival after four years) with species Hibbertia scandens (100 % survival) and Dianella brevipedunculata (58 % survival and extensive recruitment) performing the best. Grasses, including Themeda triandra, Poa labillardieri and Cymbopogon refractus, achieved a fast initial green coverage (47 % after 10 months), but showed high seasonal variability and declined to 2 %. Contrary to expectations, succulents performed poorly (<5 % green coverage, 14 % survival). Green coverage had an inverse trend to plant survival in successful plots (forbs, functionally-mixed) indicating a gap-filling effect by high performing species. Survival was more strongly linked to individual species than to functional type or plant community arrangement. Based on the results of this study, we recommend consideration of functionally-mixed green roof plantings with a variety of indigenous plants including forbs for low maintenance and resilient green coverage in the subtropics. Habitats that provided suitable plant species for this study were coastal headlands, dunes, montane areas, and open eucalypt forests. Analogous habitats in other regions can be explored to find new native plant species to increase the plant palette of potentially suitable species. It would be beneficial to trial more plants from these habitats over multiple years to increase the knowledge of suitable species available to green roof designers.

Mucilage affects seed water imbibition and germination time of subtropical monsoonal forbs

The role of seed mucilage in the moist environments of monsoonal subtropics is poorly understood. We studied germination of six forb species from subtropical monsoonal China. Mucilage presence had little to no effect on germination percentage (G%), except for a significant decline for the large-seeded Prunella vulgaris. Dark treatments reduced G% for all species, while the combination of mucilage removal and high temperatures delayed the mean germination time (MGT). Seed fresh mass was negatively correlated with G%, but only for intact seeds incubated at 12/12 hours of 25/35 °C. The MGT of de-mucilaged seeds varied with seed shape index, also under the warmer temperature regime. Temperature and light are fundamental to drive germination processes, and the presence of mucilage influences MGT of subtropical monsoonal species. Presence or absence of mucilage had little to no difference in germination percentage, but can be important to drive germination timing, also promoting water uptake and seed adhesion to soil.