Perception and plant awareness: lessons from the blind botanist and polymath John Gough (1757–1825) of Kendal

As the ecological barrier of a lake environment, lakebanks with plant/soil/microorganism systems play roles in runoff sink function. However, without proper control, the pollutants absorbed by plants can remain in plant litter and return to the water body in the plant fall season, resulting in secondary pollution. To reuse plant litter and further enhance the ecological function of lakebanks, in this study, plant litter was collected to produce biochar, which was incorporated into the lakebank soil in a microcosm. Then, the results and mechanisms of nitrogen (N) interception/removal by biochar-amended soil (biochar-based lakebank) were examined in the plant fall season (December–February) and growth season (June–August), respectively. The results showed that: (1) in both plant fall and growth seasons, the biochar-based lakebank exhibited higher total nitrogen (TN) and nitrate N (NO3−-N) removal efficiency from runoff than natural lakebank, especially in the plant growth season; (2) in the plant growth season, the TN removal efficiency of biochar-based lakebank increased by 32.85%, 12.00%, and 18.97%, and NO3−-N removal efficiency increased by 218.19%, 67.22%, and 85.91% under low, medium, and high influent pollution loads, respectively, when compared with those of natural lakebank; and (3) biochar amendment into soil promoted plant growth and increased the abundance of microorganisms related to the N cycle such as nitrobacteria, nitrifying bacteria, and aerobic denitrifying bacteria, which can further enhance the ecological function of lakebank in N removal from runoff.

Abstract—“Plant blindness” is affecting humans’ relationships with plants, which has negative consequences for both science and conservation. It is, therefore, important to find new ways to promote societal interest in botany and plants. One possibility is encouraging the use of informal settings to promote curiosity and provide education to students. Forest fragments can be regarded as open air labs for teaching botany, especially on university campuses. We aimed to formally document the angiosperm diversity in the Mata dos Saguis (MS), a fragment of Atlantic forest under restoration belonging to the central campus of the Federal University of Rio Grande do Norte (UFRN), Brazil. We recorded 140 species, 113 genera in 52 families, and 24 orders of angiosperms. The MS has nearly 10% of the species and one third of all the families occurring in the entire state of Rio Grande do Norte, representing the main evolutionary groups of angiosperms, and we also recorded two new species occurrences for the state. Here we provide a checklist of the MS, a location that has been used as an open-air laboratory by many UFRN undergraduate courses in biosciences. We also share examples that can be replicated in other institutions and discuss the process of learning systematic botany in floristically rich countries by means of alternative and hands-on experiences.

Biotic and abiotic controls in determining exceedingly variable responses of ecosystem functions to extreme seasonal precipitation in a mesophytic alpine grassland

Plants are crucial parts of ecosystems but are traditionally considered boring and difficult by students. It is therefore not clear whether factual knowledge about plants contributes to building positive attitudes and interest in botany. We investigated whether factual knowledge about monocotyledonous plants is associated with secondary students’ attitudes toward and interest in plants. Furthermore, we examined whether self-reported plant cultivation experiences and gender differences exist in attitudes toward plants. Factual knowledge about monocotyledonous plants significantly correlated with attitudes toward plants and these attitudes were greatly influenced by interest in botany, ecology, evolution, and zoology, but not with other, more distant biological disciplines (e.g. microbiology, or health and nutrition). Females received better scores in knowledge and attitudes toward plants, but interest in plants was similar between males and females. We suggest that (1) factual knowledge in botany is essential in building positive attitudes toward plants and that (2) inter-connections between botany with zoology, ecology and evolution may help with elimination of plant blindness and building positive attitudes toward plants.

Leyland cypress (X Cupressocyparis leylandii ‘Haggerston Grey’) cuttings were grown in 3.8 1 (#1), 7.6 1 (#2) and 11.4 1 (#3) containers in media combinations of pine bark, hardwood bark and coarse sand. Plants were fertilized with weekly applications of 200, 400, 600 or 800 ppm N. A growth index, percent foliar nitrogen, pH and soluble salts were detennined after 1 growing season and top dry weight was measured after 2 growing seasons. The 4 pine bark: 1 sand (v/v) and combination medium had lower pH values than the 4 hardwood bark: 1 sand medium. Percent foliar nitrogen ranged from 0.9% N to 1.34% N. Incremental N application did not increase N accumulation in leaf tissue. Increasing container size or N application did not increase the growth index through the fIrst growIng season. By the end of the second growing season plants in 11.4 1 containers were larger than those in 3.8 1 containers.

Studies on multisensory perception often focus on simplistic conditions in which one single stimulus is presented per modality. Yet, in everyday life, we usually encounter multiple signals per modality. To understand how multiple signals within and across the senses are combined, we extended the classical audio-visual spatial ventriloquism paradigm to combine two visual stimuli with one sound. The individual visual stimuli presented in the same trial differed in their relative timing and spatial offsets to the sound, allowing us to contrast their individual and combined influence on sound localization judgements. We find that the ventriloquism bias is not dominated by a single visual stimulus but rather is shaped by the collective multisensory evidence. In particular, the contribution of an individual visual stimulus to the ventriloquism bias depends not only on its own relative spatio-temporal alignment to the sound but also the spatio-temporal alignment of the other visual stimulus. We propose that this pattern of multi-stimulus multisensory integration reflects the evolution of evidence for sensory causal relations during individual trials, calling for the need to extend established models of multisensory causal inference to more naturalistic conditions. Our data also suggest that this pattern of multisensory interactions extends to the ventriloquism aftereffect, a bias in sound localization observed in unisensory judgements following a multisensory stimulus.

Leaf-wax n-alkanes are produced by terrestrial plants, and through long-term preservation in sediments their stable hydrogen-isotopic signature (δ2Hwax) provides useful information on past hydrological variation for paleoclimate reconstructions. However, gaps remain in our understanding of the relationships between the isotopic signatures of leaf waxes and the plants’ source water. In this study, we investigated the influence of plant growth form, habitat and season on the distribution patterns and δ2Hwax values of 14 plant species (among which are two grasses, five trees and seven shrubs) sampled during four successive dry and wet seasons in three distinct habitats around Lake Chala in equatorial East Africa. Variation in δ2Hwax was analyzed with linear mixed-effect models and compared with the associated values of xylem water (δ2Hxylem), leaf water (δ2Hleaf) and biosynthetic hydrogen fractionation (ebio). Our results show that plant growth form was the most important driver of modern-day δ2Hwax variability in the study area, and that differences in δ2Hwax among habitats to a large extent reflect how each major growth forms is represented in those habitats. Individual plant species appear to express substantial species-specific isotopic fractionation that cannot be attributed to the tested external factors but rather seem to depend on intrinsic (e.g., plant phenological and biosynthesis-related) factors. For the purpose of calibrating δ2Hwax signatures against vegetation types, it is thus crucial to analyze representative samples of the plant communities present in the study area. Our results further indicate that paleohydrological studies in regions receiving rain from multiple moisture sources must take into account possible seasonal bias in the δ2Hwax signature relative to annual rainfall, due to unequal use of those moisture sources by the plants. Finally, the strong influence of plant growth form on δ2Hwax values argues for δ2Hwax variation in paleo-records being evaluated in conjunction with independent proxy data on changes in vegetation composition. Differences in n-alkane distribution patterns among trees, shrubs and grasses (e.g., average chain length, carbon preference index and C31/(C29 + C31) ratio) may provide such proxies, and can be produced from the same leaf-wax n-alkane dataset used to determine δ2Hwax.

Trends of increasing global air temperatures are shifting the water balance of many ecosystems with drastic subsequent effects for vegetation. Dew is thought to be particularly sensitive to atmospheric changes due to its fundamental reliance on the interaction between water vapor and temperature. While several studies have shown that dew can be an important water source for specific plant species, efforts have consisted of a subset of species over short periods, leaving a knowledge gap concerning the effects of dew on ecosystems across larger spatial and temporal extents. Here we use hourly climate data from 221 stations in Germany and remote sensing of plant greenness during the growing season to understand: What are the long-term trends in dew amount in Germany, and are they influencing seasonal plant growth? Our results indicate that long-term changes in dewfall are common across Germany, with 30% of our sites showing significant declines in dew amount over the last 20 years, whereas 12% show significant increases in dew. We found that total dew accumulation had small but significant effects on vegetation greenness across Germany. On average, we estimate that during the growing season, dew increases peak greenness by four percent and total cumulative greenness by three percent. Dew impacts on greenness metrics indicate it has an important role in plant ecosystem health and productivity. Current atmospheric trends may not only decrease the amount of dew during the growing season in Germany, but also lead to higher water deficit, where dew amount plays a larger role in water and energy balance.

Bacillus subtilis B579, which was isolated from rhizosphere of cucumber, exhibited an excellent biocontrol activity on soil-born pathogens under greenhouse conditions. It could colonize in rhizosphere of cucumber with large number of populations after inoculated in plant growth season. To reveal the effect of high level colonization of B. subtilis B579 on rhizobacteria community structure, cultivation-based analysis coupled with denaturing gradient gel electrophoresis (DGGE) analysis were used to profile the changes of rhizobacteria community structure sampling at 1week interval. Cultivation-based and DGGE fingerprinting analysis showed significant plant-dependent and seasonal shifts in rhizobacteria populations. Only minimal and transient effects were observed at 4-9weeks after sowing in samples of B579 treatment, without the pathogen inoculation and showed the best plant growth potential. Sequencing of dominant bands excised from the gel revealed that Streptomyces sp. was the dominate species in soils before and after sowing. Burkholderia sp. was the dominate species in bulk soil, while Bacillus sp. was dominated in rhizosphere within the growth season. Arthrobacter ramosus and Nocardioides sp. were identified as the specific species in samples treated by B579 at the maturity and flowering stages of cucumber.

To assess the impact of the biocontrol strain Pseudomonas fluorescens CHA0 on a collection of barley rhizosphere bacteria using an agar plate inhibition assay and a plant microcosm, focusing on a CHA0-sensitive member of the Cytophaga-like bacteria (CLB). The effect of strain CHA0 on a collection of barley rhizosphere bacteria, in particular CLB and fluorescent pseudomonads sampled during a growth season, was assessed by a growth inhibition assay. On average, 85% of the bacteria were sensitive in the May sample, while the effect was reduced to around 68% in the July and August samples. In the May sample, around 95% of the CLB and around 45% of the fluorescent pseudomonads were sensitive to strain CHA0. The proportion of CHA0-sensitive CLB and fluorescent pseudomonad isolates decreased during the plant growth season, i.e. in the July and August samples. A particularly sensitive CLB isolate, CLB23, was selected, exposed to strain CHA0 (wild type) and its genetically modified derivatives in the rhizosphere of barley grown in gnotobiotic soil microcosms. Two dry-stress periods were imposed during the experiment. Derivatives of strain CHA0 included antibiotic or exopolysaccharide (EPS) overproducing strains and a dry-stress-sensitive mutant. Despite their inhibitory activity against CLB23 in vitro, neither wild-type strain CHA0, nor any of its derivatives, had a major effect on culturable and total cell numbers of CLB23 during the 23-day microcosm experiment. Populations of all inoculants declined during the two dry-stress periods, with soil water contents below 5% and plants reaching the wilting point, but they recovered after re-wetting the soil. Survival of the dry-stress-sensitive mutant of CHA0 was most affected by the dry periods; however, this did not result in an increased population density of CLB23. CLB comprise a large fraction of barley rhizosphere bacteria that are sensitive to the biocontrol pseudomonad CHA0 in vitro. However, in plant microcosm experiments with varying soil humidity conditions, CHA0 or its derivatives had no major impact on the survival of the highly sensitive CLB strain, CLB23, during two dry-stress periods and a re-wetting period; all co-existed well in the rhizosphere of barley plants. Results indicate a lack of interaction between the biocontrol pseudomonad CHA0 and a sensitive CLB when the complexity increases from agar plate assays to plant microcosm experiments. This suggests the occurrence of low levels of antibiotic production and/or that the two bacterial genera occupy different niches in the rhizosphere.

Removal of low concentration nutrients in hydroponic wetlands integrated with zeolite and calcium silicate hydrate functional substrates

To find out the secular and seasonal trends of the δ13C value and CO2 concentration in the surface air and the determination of the δ13C in the atmospheric CO2 collected at Tsukuba Science City was carried out during the period from July 1981 to October 1983. The monthly average of the δ13C value of CO2 in the surface air collected at 1400 LMT ranged from -7.52 to \s-8.45‰ with an average of -7.96±0.25‰ and the CO2 concentration in the air varied from 334.5 μl 1-1 to 359 μl 1-1 with an average of 347.2±6.3 μl 1-1. The δ13C value is high in summer and low in winter and is negatively correlated with the CO2 concentration. In general, the relationship between the δ13C and the CO2 concentration is explainable by a simple mixing model of two different constant carbon isotopic species but the relationship does not always follow the model. The correlation between the δ13C value and the CO2 concentration is low during the plant growth season and high at other times. The observed negative deviation of the δ13C value from the simple mixing model in the plant growth season is partly due to the isotopic fractionation process which takes place in the land biota.

The presence of salts in the leaf exudate improves the photosynthetic performance of a recreto-halophyte, Tamarix chinensis

Modelling alteration of leaf coloration peak date in Cotinus coggygria in a high-elevation karst region

A obvious feature of many coastal wetlands is the relatively low plant species richness across different plant zones. The mechanisms of low plant species richness in the coastal wetland still need to be investigated. On the other hand, seed addition and litter removal are traditional measures to increase plant species richness in degraded ecosystems (such as grasslands and forests), but the effects of these interventions has not been greatly explored in coastal wetlands. We performed a seed addition and litter removal experiment in three coastal marsh vegetative zones characterized by Suaeda salsa, Aeluropus pungens, and Phragmites australis in the Yellow River Delta. The results showed that seed addition and litter removal treatments did not increase the species richness, plant density, or above-ground biomass over one growth season in each zone. We further found that the mechanisms limiting these measures was salinity in S. salsa and A. pungens zones, and water inundation in the P. australis zone, which may limit seed germination and seedling recruitment. Specifically, seed addition increased plant density of P. australis in the early growth season (May and June), but decreased it dramatically at the end of the growth season (September) due to water inundation. The interactive effect of seed addition and litter removal on average plant height varied by plant zone and growth season. Limitations in both seed germination and seedling recruitment may lead to lower species richness in coastal marsh plant zones and, more generally, it is unlikely that seed addition and litter removal will increase species richness in plant zones of degraded coastal wetlands with high environmental stress.