Plant Population Characteristics Research Articles

Spatio-temporal variation of seed rain between urban and rural fragments of humid tropical forests

Introduction: The type of land use surrounding the remnants of tropical forest may generate changes in the characteristics of plant populations and communities. Consequently, there may be a significant reduction in processes of pollination and diasporas dispersion. Therefore, causing changes in some parameters of seed rain. Objective: To characterize and compare seed density, species richness, floristic composition, habit, dispersal syndrome, and successional category of seed rain between urban and rural fragments of Atlantic Forest, in the 2015 and 2016 weather seasons. Methods: The study areas were defined after mapping and quantification of urban and rural occupations around the remnants, based on satellite images. In each fragment, were installed 36 collectors of 0.25 m2. The material was collected monthly during two consecutive years. Results: Seed rain richness was higher in the urban fragment during the rainy season in the two years, whereas it was similar between the fragments in the dry season. The seed density in the rural fragment was higher than in the urban during the rainy season; did not vary in urban between years or between seasons; and it was higher in the rural fragment in the rainy season of one year. There was a difference in the floristic composition of the seed rain between the fragments along time. The variations in the functional attributes of habit, dispersal syndrome, and successional category, were explained by the variables fragment, season, and year. Conclusions: Differences in the characteristics of the seed rain between the fragments might reflect the spatial and temporal heterogeneity, due to the diverse uses of the soil and external pressures (anthropogenic actions) present in the surroundings of the forest fragments and temporal variation in precipitation.

Effects of Nutrient Addition on Pedicularis kansuensis Invasion of Alpine Grassland

In order to study the changes in invasive plant population characteristics under different nutrient addition treatments, this study used the native invasive species Pedicularis kansuensis, which is spreading in the Bayabulak alpine grassland, as the research object and conducted two consecutive years of field studies in which nutrients were added to plots. Changes in the P. kansuensis population’s invasive characteristics were monitored in 2020 and 2021 in four different nutrient-addition treatments, namely no-nutrients (control), low-nitrogen, high-nitrogen, and phosphorus treatments. The result showed that (1) nutrient addition had significant effects on P. kansuensis height and root/shoot ratio (p < 0.05); the time effect had significant effects on P. kansuensis height, coverage, abundance, aboveground biomass, and belowground biomass (p < 0.01), and the interaction between nutrient addition and time had a significant effect on P. kansuensis height (p < 0.01). (2) Nitrogen addition effectively inhibited the growth and the development of P. kansuensis, especially under high-nitrogen conditions in the second growing season, where the effect of height (2.50 cm), coverage (0.13%), richness (3 strains), aboveground biomass (0.21 g m−2), and belowground biomass (0.03 g m−2) was significant, with the P. kansuensis population almost disappearing by the end of the trial. (3) Phosphorus addition had no significant effect on the P. kansuensis population’s invasive characteristics. These results indicate that higher nitrogen addition could effectively slow the invasion of the P. kansuensis population, and the findings of this study could provide certain baseline data and scientific guidance for the effective control of the P. kansuensis invasion of the Bayabulak alpine grassland in the future as well as identify certain theoretical bases for the effect of nutrient addition on invasive plants overall.

PREDICTION OF CORN GRAIN PRODUCTIVITY AS A FUNCTION OF ALTITUDE AND PLANT POPULATION

This study aimed to evidence the best arrangement of plants according to altitudes to potentialize corn grain yield. An information survey was performed in the 2019/20 harvest, using 144 producers responsible for corn grain production fields totaling 2,301.3 hectares in 144 environments of Rio Grande do Sul. Within 144 environments, 14 corn hybrids were arranged: DKB 240 PRO, DOW 2A620, AG 9045 PRO3, AS1555 PRO3, AS1572 PRO2, AS1656, BIOGENE 7046, DKB 250 PRO2, DKB 290 PRO3, DKB 330RR, NS56, P1630HX, P30F53HX, and SH7910. Yield, morphological, and phenological variables were measured, and geographic and meteorological information was collected. There is a positive influence on grain yield according to altitude and plant population characteristics. At lower altitudes, increasing plant population is essential to enhance grain yield.

生境破碎对古尔班通古特沙漠南缘骆驼刺种群生物学特性的影响

在破碎化生境中，植物种群的生物学特性直接反映植物对环境的响应特征和适应对策，探讨不同破碎化程度生境中植株的大小、密度、结实率、种子大小、种子质量以及萌发特性等，对深入了解植物在不同生境中的生存和繁殖状况有重要的指导意义。对古尔班通古特沙漠南缘9个斑块化骆驼刺种群的形态特征和繁殖生物学参数进行了连续2年的调查研究，研究结果表明：随着生境破碎化程度的加剧，骆驼刺的株高、冠幅、密度、结实率、种子大小、种子质量以及萌发率等均显著下降（P < 0.05）。生境破碎不仅强烈抑制了骆驼刺植株的营养生长，使其生长矮小，个体分布稀疏，而且严重阻碍了骆驼刺的繁殖成功和种群更新，增加了种群衰退甚至灭绝的风险。;In the fragmented habitats, the biological characteristics of plant populations directly reflect the plant's response and adaptation to the environment. Researches on the size, density, seed setting rate, seed size, seed quality, and seed germination characteristics of plants in different fragmented habitats have important guiding significance for in-depth understanding of plants' survival and reproduction strategies. In this study, the morphological characteristics and reproductive parameters of Alhagi sparsifolia populations in nine patches at the southern margin of the Gurbantunggut Desert were investigated in 2018 and 2019. The results showed that with the increase of the degree of habitat fragmentation, the height, crown width, density, seed setting rate, seed size, seed quality, and seed germination rate of A. sparsifolia decreased significantly. The habitat fragmentation not only significantly inhibited the vegetative growth of A. sparsifolia, but also led to the sparsely distribution that seriously hindered its reproduction and population regeneration, increasing the risks of population depression and extinction.

Application of UAV aerial image in monitoring and maintenance of expressway green belt

The function of highway greening project is mainly classified from three aspects of central separation belt greening, slope greening and road side greening, and the initial indexes of various highway greening evaluation will bring great workload to the post-maintenance work. High-throughput highway inspection and monitoring platform is of great significance to the qualitative and quantitative evaluation of highway greening project. The UAV platform monitors the population shape of the plant in the central green belt of the highway, has the advantages of higher flux, high reduction degree and low cost, and is an important development direction of highway greening project maintenance in the future. Based on the present situation of maintenance and repair of highway greening project, the information acquisition technology of plant population characteristics and the systematic summary of the function of highway green belt, this paper mainly discusses the application prospect of UAV quantitative remote sensing technology in the monitoring of functional index of highway green belt, which is the driving safety of highway, the design of green belt, structural optimization and maintenance management provide theoretical support.

The self-thinning rule and plant population modelling with resource constraints

The Japan Agency for Marine-Earth Science and Technology contributed this challenge to the 2016 Mathematics-in-Industry New Zealand Study Group Workshop. It concerned implications of the self-thinning rule for modelling plant population characteristics via a partial differential equation governing the temporal evolution of the density distribution of plants of a particular size. The self-thinning rule is empirically observed for crowded populations under constrained resources. We investigate the theoretical consequences of a resource constraint on the partial differential equation of interest, and through numerical experiments reveal a surprisingly strong link between imposition of the resource constraint, and populations that evolve according to the self-thinning rule. The result is a simple condition between growth and mortality functions that implies self-thinning behaviour, and motivates further mathematical investigation.

Approaching the concepts of ecosystems resilience and stability through spatiotemporal system dynamics and agent-based modelling

We introduce a simplified ecohydrological model to quantitatively assess the resiliency and stability of ecosystems over long periods. The model couples a hydrological soil moisture balance with a set of spatiotemporal systems dynamics and agent-based algorithms to represent the interactions among several plant populations in a gridded area under different water, soil and temperature constraints. We characterize the plant populations by allometric rules (i.e., power laws for generational and reproductive times; linear approximations for water and temperature gains, losses and optimal values; and a set of intra and interspecific interaction rules based on high, optimal and low competition responses among the populations), that represent different plant phenotypes. We define the disturbances by a clearance of populations in an area within the model’s domain and calculate the resiliency and stability with simple indices to determine the ability of the ecosystem to recover from a disturbance. The indices evaluated on each population and over the structure of the entire ecosystem show how the populations respond differently to disturbances, following patterns similar to those expected in nature. The model can represent the spatial and temporal succession of the ecosystem after being disturbed, suggesting how the differences in the phenotypical characteristics of plant populations can be advantageous or disadvantageous for the ecosystem recovery.

Sap flow and trunk maximum daily shrinkage (MDS) measurements for diagnosing water status of Populus euphratica in an inland river basin of Northwest China

ABSTRACTUsing sap flow flux density and trunk maximum daily shrinkage (MDS) as the main plant‐based water stress indicators and combined with soil salinity parameters and plant population characteristics, water statuses of Populus euphratica were diagnosed. Based on these parameters, optimal groundwater depth for maintaining the development of natural P. euphratica were explored in middle and lower reaches of the Tarim River. When excluding the impact of soil salinity and climatic factors, our results demonstrated that sap flow flux density in P. euphratica decreases with increase groundwater depth and that such a negative correlation is significant. It also showed that MDS has a significant positive correlation with groundwater depth. When the water table depth reached 4.5–5.0 m, our study showed a significant reduction in sap flow flux density changes of P. euphratica apparent and increasing MDS, indicating that the growth of P. euphratica is under drying stress, and the plant adapts to the environment through reducing transpirational water consumption by self‐regulation. When water table is in the range of 4–6 m, the populations characteristics (coverage, density and frequency) of P. euphratica under different groundwater depth reached the maximums. We conclude that groundwater depth between 4.5 and 5.0 m is the optimum restoring P. euphratica and its ecosystem in the middle and lower reaches of the Tarim River. Copyright © 2013 John Wiley &amp; Sons, Ltd.

The impact of habitat fragmentation on the interaction betweenCentaurium erythraea(Gentianaceae) and its specialized seed predatorStenoptilia zophodactylus(Pterophoridae, Lepidoptera)

AbstractHabitat fragmentation can affect plant population characteristics and plant traits, which in turn can change biotic interactions, such as plant–insect interactions. Because of this, habitat fragmentation can affect reproductive success and survival of both the plant and seed predators, especially when the predator is rare and specialized. This study focuses on the level of fruit predation inCentaurium erythraeaby its specific seed predator, the plume mothStenoptilia zophodactylus, in a fragmented coastal dune landscape. To investigate the consequences of habitat fragmentation, we assessed the effect of population and plant characteristics of 25C. erythraeapopulations on fruit predation byS. zophodactylus. Although the distribution of this specialized predator is poorly documented, our results show thatS. zophodactylusoccurred frequently in most of the studiedC. erythraeapopulations. We found a strong correlation between the spatial isolation of the host plant and the level of fruit predation, with low predation in isolated populations, most likely due to the limited dispersion capacity of the plume moth.C. erythraeaindividuals experienced a higher risk of fruit predation when showing a large floral display size, presumably because they are more attractive. However, at fruit level, the risk of predation decreases with increasing floral display at individual plant level, representing a sort of dilution effect. Our findings indicate that maintaining and restoring large, dense and rather connected populations ofC. erythraeawill be beneficial for the sustainable conservation of the rare specialist seed predatorS. zophodactylus, without increasing the predation pressure on the host plant.

Relationships among nectar‐dwelling yeasts, flowers and ants: patterns and incidence on nectar traits

Nectar‐dwelling yeasts are emerging as widely distributed organisms playing a potentially significant and barely unexplored ecological role in plant pollinator mutualisms. Previous efforts at understanding nectar–pollinator–yeast interactions have focused on bee‐pollinated plants, while the importance of nectarivorous ants as vectors for yeast dispersal remains unexplored so far. Here we assess the abundance and composition of the nectar fungal microbiota of the ant‐pollinated plant Cytinus hypocistis, study whether yeast transmission is coupled with ant visitation, and discern whether ant‐ transported yeasts promote changes in nectar characteristics. Our results show that a high percentage of flowers (77%) and plants (94%) contained yeasts, with yeast cell density in nectar reaching up to 6.2 × 104 cells mm−3, being the highest densities associated with the presence of the nectar‐specialist yeast Metschnikowia reukaufii. The establishment of fungal microbiota in nectar required flower visitation by ants, with 70% of yeast species transported by them being also detected in nectar. Ant‐vectored yeasts diminished the nutritional quality of nectar, with flowers exposed to pollinators and yeasts containing significantly lower nectar sugar concentration than virgin flowers (13.4% and 22.8%, respectively). Nectar of flowers that harbored M. reukaufii showed the lowest quality, with nectar concentration declining significantly with increasing yeast density. Additionally, yeasts modified patterns of interpopulation variation in nectar traits, homo genizing differences between populations in some nectar attributes. We show for the first time that the outcome of the tripartite pollinator–flower–yeast interaction is highly dependent on the identity and inherent properties of the participants, even to the extent of influencing the species composition of this ternary system, and can be mediated by ecological characteristics of plant populations. Through their influence on plant functional traits, yeasts have the potential to alter nectar consumption, pollinator foraging behavior and ultimately plant reproduction.

Higher fine-scale genetic structure in peripheral than core populations of a long-lived and mixed-mating conifer - eastern white cedar (Thuja occidentalis L.)

BackgroundFine-scale or spatial genetic structure (SGS) is one of the key genetic characteristics of plant populations. Several evolutionary and ecological processes and population characteristics influence the level of SGS within plant populations. Higher fine-scale genetic structure may be expected in peripheral than core populations of long-lived forest trees, owing to the differences in the magnitude of operating evolutionary and ecological forces such as gene flow, genetic drift, effective population size and founder effects. We addressed this question using eastern white cedar (Thuja occidentalis) as a model species for declining to endangered long-lived tree species with mixed-mating system.ResultsWe determined the SGS in two core and two peripheral populations of eastern white cedar from its Maritime Canadian eastern range using six nuclear microsatellite DNA markers. Significant SGS ranging from 15 m to 75 m distance classes was observed in the four studied populations. An analysis of combined four populations revealed significant positive SGS up to the 45 m distance class. The mean positive significant SGS observed in the peripheral populations was up to six times (up to 90 m) of that observed in the core populations (15 m). Spatial autocorrelation coefficients and correlograms of single and sub-sets of populations were statistically significant. The extent of within-population SGS was significantly negatively correlated with all genetic diversity parameters. Significant heterogeneity of within-population SGS was observed for 0-15 m and 61-90 m between core and peripheral populations. Average Sp, and gene flow distances were higher in peripheral (Sp = 0.023, σg = 135 m) than in core (Sp = 0.014, σg = 109 m) populations. However, the mean neighborhood size was higher in the core (Nb = 82) than in the peripheral (Nb = 48) populations.ConclusionEastern white cedar populations have significant fine-scale genetic structure at short distances. Peripheral populations have several-folds higher within-population fine-scale genetic structure than core populations. Anthropogenic disturbances and population fragmentation presumably have significant effects on fine-scale genetic structure in eastern white cedar. Core populations have higher neighborhood size than peripheral populations, whereas gene flow distances are higher in peripheral than in core populations. The results of our study contribute to the knowledge of poorly-understood spatial genetic structure of core versus peripheral populations in plants. As well, the information is of significance for conservation of genetic resources of eastern white cedar and perhaps of other long-lived forest trees with mixed-mating system.

Persistence of Phalaris aquatica in grazed pastures. 1. Plant and tiller population characteristics

Phalaris tiller and plant population characteristics were monitored in sown Australian phalaris–subterranean clover pastures over 3 seasons (1999–2001) to determine the impact of fertiliser and grazing method on phalaris persistence in south-western Victoria. Four grazing systems were tested: set-stocked, low phosphorus (P) fertiliser input (SS low P); set-stocked, high P fertiliser input (SS high P); simple rotation, high P (RG 4 paddock); and intensive rotation, high P (RG intensive). Within each year there was no significant difference in tiller density (tillers/m2) between the grazing systems. Phalaris tiller density declined (P&lt;0.05) on all treatments from June 1999 to June 2001. There was a significant effect of grazing method on tiller size (mg/tiller); tillers growing under rotational grazing systems were much larger than those in set-stocked systems. There was some evidence of tiller size density compensation across the grazing management treatments; however, the slope of the trade-off between tiller size and density was not as steep as those reported for other species. In general, the phalaris tiller populations under rotationally grazed treatments were characterised by lower density per m2 of phalaris clump and larger size, compared with the set-stocked treatments. Both the phalaris tiller and clump density declined at a similar rate on all treatments during this experiment, suggesting that there was some limitation to phalaris persistence irrespective of grazing system. Measured leaf appearance intervals (days/leaf) indicated that a lack of tillering sites was not a contributing factor in the observed tiller density decline. It is likely that the combination of high grazing pressure, below average rainfall and subsoil acidity contributed to the observed phalaris population decline.

Produção de capítulos florais da camomila em função de populações de plantas e da incorporação ao solo de cama-de-aviário

O experimento foi realizado no horto de plantas medicinais da Universidade Federal de Mato Grosso do Sul, em Dourados, de abril a setembro/2000. Avaliou-se o efeito do uso de cama-de-aviário semidecomposta incorporada ao solo e populações de plantas sobre as características morfológicas, a produção e a qualidade do óleo essencial dos capítulos florais da camomila cv. 'Mandirituba'. Os fatores em estudo deram origem aos nove tratamentos, combinando respectivamente espaçamentos entre plantas (m) e cama-de-aviário (kg m-2): 0,16 e 1,2; 0,24 e 1,2; 0,16 e 2,8; 0,24 e 2,8; 0,20 e 2,0; 0,11 e 1,2; 0,29 e 2,8; 0,16 e 0,2 e 0,24 e 3,8, dispostos no delineamento experimental de blocos casualizados, com quatro repetições. As características avaliadas foram altura de plantas; número, altura e diâmetro, massa fresca e seca e análise qualitativa do óleo essencial dos capítulos florais. A altura média máxima das plantas da camomila 'Mandirituba' foi de 0,61 m, sendo considerada cultivar de porte baixo. Não houve efeito significativo da interação espaçamentos entre plantas e cama-de-aviário sobre as características avaliadas. A produção dos capítulos florais foi influenciada mais intensamente pelo espaçamento entre plantas do que pela cama-de-aviário. O menor espaçamento induziu os maiores números (56,57 milhões ha-1) e massas secas dos capítulos florais (1.080 kg ha-1). As alturas (0,71 a 0,81 cm aos 100 dias e 0,68 a 0,71 cm aos 116 dias após transplante), o diâmetro (1,96 a 2,13 cm aos 100 dias e 1,83 a 1,91 cm aos 116 dias após transplante) e a massa unitária dos capítulos florais (0,12 g) não foram significativamente influenciados pelos tratamentos estudados. A produção média de massa seca dos capítulos florais (800 kg ha-1) foi maior que a média brasileira convencional (500 kg ha-1). O óleo essencial obtido, nas amostras dos nove tratamentos, apresentou cor azul intensa e odor característico, como descrito na literatura para os óleos de boa qualidade e apropriados para a comercialização.

The Effects of Boat Docks on Eelgrass Beds in Coastal Waters of Massachusetts

/ The effects of docks on eelgrass beds were measured using plant population characteristics (shoot density, canopy height, and growth rates), light levels, and an assessment of eelgrass bed quality in Massachusetts estuaries. Eelgrass populations were impacted under and directly adjacent to docks, as shown by depressed shoot density and canopy structure. Severe impacts can cause fragmentation of eelgrass beds, thus contributing to large-scale declines in estuaries such as Waquoit Bay. Impacts were fewer under docks supported by piers than under floating docks, and taller piers resulted in fewer impacts. Based on this investigation, we conclude that docks should be greater than 3 m in height above the bottom in areas with tidal ranges less than 1 m to allow enough light to sustain eelgrass beds under the docks. In addition to dock height, orientation and width were also found to be important factors affecting eelgrass. Narrow docks with a north-south orientation can best ensure the long-term survival of eelgrass under and near the dock. KEY WORDS: Docks; Shade; Eelgrass beds; Zostera marina; Seagrass

Seed Dormancy Implications in Grain and Forage Production

Seed dormancy has been described for many species, and has promoted the curiosity of ecologists, who have recorded in detail the conditions and periods where seed dormancy is present. Physiologists have focused on understanding the mechanisms involved in seed dormancy induction and release. Agronomists have found seed dormancy to be problematic since it is related to the development of persistent weed seed banks and to the problems in predicting establishment of weed stands. If the crop seed has dormancy, its germination is restricted to a very narrow range of micro-environmental conditions. In this paper, we discuss how seed dormancy and the knowledge of its nature could be used to improve agronomic practices for grain and forage production. Crops selected to have dormant seeds, or artificially generated dormant seeds, could be sown at any time. When seedling establishment is desired, seed dormancy level could be lowered to produce synchronic germination and seedling emergence by modifying the environment, (i.e., changing the light and thermal environment of the seeds) so that physiological changes could occur and trigger germination. Seed germination could be naturally induced by seasonal changes or artificially induced by sonication. Selecting crops with dormant seeds during ripening and storage could also prevent seeds from germinating in moist environments. Artificially induced seed dormancy could be achieved by spraying hormones or oils. With adequate knowledge about the seed dormancy characteristics of plant populations, environmental situations can be engineered to encourage release from seed dormancy, to promote or inhibit certain species in weed and range management.

Determination and application of vision standards in industry.

Job-related vision standards benefit both employee and employer. By comparing employees' vision to specific job requirements, workers can be better placed into positions commensurate with their visual abilities. For a company without a vision care program, a project was undertaken to determine visual standards, and the need for vision care services for employees to better meet these standards. The critical factors for performing specific visual tasks for 40 job classifications were identified through direct observation and measurement, and through worker interviews. Additionally, a sample of employees was screened to determine plant population characteristics, and to determine what percentage of employees met the newly formed standards. This study can serve as a model for the application of visual standards to the workplace and is pertinent, as "reduced vision" is increasingly defined by government as a disability.

Sustenance and Symbol: Anthropological Studies of Domesticated Animals

For nearly as long as anything can be inferred about human cognition, paleoan­ thropologists and archaeologists believe humans have thought carefully about animals, about the "predominant characteristic" of each animal, and about those "contradictory elements" that make up humankind. This careful thought has had many outcomes, some scientific, others not . Among the scientific outcomes in the 19th century was evolutionary thinking about the causes and consequences of domestication, including Charles Dar­ win's study (32) of the mechanics of human (artificial) selection of domesti­ cated animal and plant population characteristics. In the 20th century, theoreti­ cal refinements and the painstaking collection of empirical data have led to studies of such disparate phenomena as the physical consequences of keeping pets (12); the spread of antibiotic-resistant bacteria as a result of feeding antibiotics to livestock (117); and the evolutionary consequences of milk­ drinking (99). Speculation about the origins of human-animal interaction is not the exclu­ sive province of scientists: religions and storytellers alike customarily try to account for the beginnings of human-animal interaction . Genesis does so

The population structure and density of central Australian trees and shrubs, and relationships to range condition, rabbit abundance and soil.

The regional variation in population structure and density of trees and shrubs was investigated in four central Australian pasture types: open woodland, mulga annual, calcareous shrubby grassland and bluebush nse. The possible influences of range condition, rabbit abundance, soil erosion and so11 characteristics were examined, and the likelihood of long-term change was cons~dered. Density at some woodland and mulga sites was potentially high enough to depress pasture yield. The most common "increaser"species were Casszaspp. in open woodland and mulga (Acaciaaneura) in mulga annual. None of the measured influences related closely to population structure and density, and it is argued that changed fire regimes are most likely to have led to increasing densities of trees and shrubs. Density in calcareous shrubby grasslands was related to rabbit abundance, and smaller size classes of trees and shrubs were severely depleted whererab- bits were plentiful. Continuing loss of the woody plant resource is forecast, if rabbits are not controlled. Other measured influences were not related to woody plant population characteristics. Bluebush (Maireana miroiricha) populations were considered to be relatively stable under current management of bluebush rises.