Composition Of Herbaceous Plants Research Articles

Effects of nitrogen addition on species composition and diversity of early spring herbs in a Korean pine plantation.

Under the background of global nitrogen deposition, temperate forest ecosystems are suffering increasing threats, and species diversity is gradually decreasing. In this study, nitrogen addition experiments were conducted on Korean pine (Pinus koraiensis) plantations in Northeast China to explore the effect of long-term nitrogen addition on herb species diversity to test the following hypothesis: long-term nitrogen addition further reduced plant species diversity by affecting plant growth, which may be due to soil acidification caused by excessive nitrogen addition. Experimental nitrogen addition was conducted from 2014 to 2021, and the nitrogen treatment levels were as follows: N0 (control treatment, 0/(kg N ha-1 year-1)), N20 (low nitrogen treatment, 20/(kg N ha-1 year-1)), N40 (medium nitrogen treatment, 40/(kg N ha-1 year-1)) and N80 (high nitrogen treatment, 80/(kg N ha-1 year-1)). A herb community survey was conducted in the region from 2015 to 2021. The results showed that long-term nitrogen addition decreased soil pH, changed the species and composition of herbaceous plants, and decreased the species diversity of understory herbaceous plants. With the increase in nitrogen application years, middle- and high-nitrogen treatments significantly reduced the diversity of early-spring flowering herbs and early-spring foliating herbs, and their diversity decreased with the decrease in soil pH, indicating that soil acidification caused by long-term nitrogen addition may lead to the decrease of plant diversity. However, for early-spring growing herbs, adequate nitrogen addition may promote their growth. Our results show that plants have evolved different life-history strategies based on their adaptation mechanisms to the environment, and different life-history strategies have different responses to long-term nitrogen addition. However, for most plants, long-term nitrogen application will have a negative impact on the growth and diversity of herbs in temperate forests.

АНАЛИЗ СОСТОЯНИЯ ТРАВЯНИСТОЙ РАСТИТЕЛЬНОСТИ ПРИВОКЗАЛЬНЫХ ТЕРРИТОРИЙ ГОРОДОВ КОЛЬСКОЙ СУБАРКТИКИ

The study of species diversity and the state of grassy ground cover in the station territories of 5 cities of the Murmansk region (Murmansk, Apatity, Olenegorsk, Polyarnye Zori, Kandalaksha) have been carried out. It has shown that the floristic composition of herbaceous plants was monot-onous, poor and was represented by species characterized by a wide range of ecological tolerance. Common species found in all cities were Taraxacum officinale Taraxacum officinale Wigg. s. l., Trifolium repens L., Achillea millefolium L., Equisetum arvense L., E. Palustre L., Rumex confer-tus L. and cereals (Dactylis glomerata L., Deschampsia cespitosa (L)., Festuca rubra L., Festuca pratensis Huds., Poa annua L., Poa pratensis L., Phleum pratense L.). The greatest species diver-sity was found in Apatity and Polyarnye Zori. The plant state was satisfactory, no pests and dis-eases were found, no damage in the form of necrotic spots was noted. Of the ornamental flower plants, 20 species were found, Aconite firmum Reichenb., Primula elatior (L.) Hill var. tatrica Domin, Primula amoena Bieb. were widely distributed. The analysis of the projective cover of herbaceous vegetation showed the presence of a different number of areas with disturbed ground cover. The highest percentage of wastelands (56%, due to trampling and other types of anthropo-genic impact) was found in Olenegorsk, the least – in Kandalaksha (84%).

Обґрунтування природної цінності території "Дублянського парку" для надання статусу парку-пам'ятки садово-паркового мистецтва

Проаналізовано ландшафтну, планувальну, просторову структури "Дублянського парку" Самбірського району Львівської області. Встановлено, що на дослідженій території відсутні ознаки функціонального зонування, немає проєкту організації його території. Об'ємно-просторова структура цього парку, в основному, представлена закритим простором. Напіввідкриті простори виявлені вздовж русла річки Веретено та алеї біля північної межі парку. Переважає лісовий тип ландшафту, який виник на місці порушеного паркового ландшафту. Залишились окремі елементи регулярного парку у вигляді ділянки перерослого грабового боскету, які потребують реконструкції та збереження. Визначено основні види деревних і трав'яних рослин, що присутні на території, запропонованій для охорони у смт Дубляни Самбірського району. У дендрофлорі дослідженого парку більшість рослин належить до відділу Magnoliophyta. Видовий склад деревних рослин представлений 39 видами, які належать до 16 родин. Серед життєвих форм, які формують основу цього парку, переважають дерева (30 таксонів). Кущі представлені такими лісовими видами: Euonymus europaeus L., Cornus sanguinea L., Rosa canina L. У складі паркового фітоценозу смт Дубляни присутні інтродуковані вікові види, а саме: Juglans nigra L. та J. мandshurica Maxim,, Phellodendron amurense Rupr, Acer sacharinum L. та A. negundo L. За таких умов зростання для цих видів характерна досить висока стійкість, деякі з них дають природне поновлення, мають історичну та ботанічну цінність. У складі трав'яних рослин, здебільшого, переважають лісові види, що свідчить про відсутність належного догляду і витіснення штучних угруповань. Найвища частота трапляння та проєктивного вкриття спостерігається у Carex brizoides L., Stellaria holostea L., Aegopodium podagraria L., Pulmonaria obscura Dumort., Galeobdolon luteum Huds. Узагальнено назрілі проблеми функціонування досліджуваного парку, встановлено причини деградації зелених насаджень, намічено невідкладні природоохоронні та ландшафтно-планувальні завдання, обґрунтовано доцільність надання парку статусу парку-пам'ятки садово-паркового мистецтва місцевого значення у смт Дубляни Самбірського району Львівської області.

Floristic composition and distribution pattern of herbaceous plant diversity in fallow lands of the central districts of Punjab, India

This study explores the change in composition of herbaceous plants with change in season and site in the fallow lands of central districts of Punjab, India. Overall 41 plant species were reported from studied sites. Poaceae and Asteraceae were recorded as dominant families with seven and six plant species, respectively. Density and IVI values of perennial plant species were recorded to be the maximum from July to September and for annuals maximum values were from February to March and from July to September. Diversity indices like Shannon Wiener index, evenness index, Menhinick index, and Simpson diversity index values showed variation with season and site. Similarity index value between studied sites was recorded to be the minimum in July (0.45) which indicates a maximum value of dissimilarity index in this month. The information generated in this study can be exploited by researchers for conservation of natural plant diversity and timely assessments of such areas help to study climate change.
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Influence of the herbaceous layer and litter depth on the spatial distribution of litter macrofauna in a forest plantation

The litter invertebrate community consists of species from different size, trophic and taxonomic groups. The distribution of the animal population of the litter horizon depends upon many factors, especially the content of the phytocoenosis, the projective herbaceous plant cover, moisture, litter thickness and the soil texture. This article analyses the variability of the main characteristics of litter invertebrate communities (total number, number of species, diversity according to the Shannon–Wiener and Pielou indices) on plots with different herbaceous plant composition and cover in plantations of Robinia pseudoacacia L. in the South steppe zone of Ukraine (territory of the “Tiligulsky” Regional Landscape Park). The taxonomic structure of the litter communities in the Robinia plantation was dominated by predatory groups of invertebrates (Carabidae, Aranea, Formicidae). The abundance of Julidae, Isopoda, Silphidae and Staphylinidae was relatively low. The studied forest plots were characterized by the simplified size structure of the litter macrofauna. The absence of species with body length of 16–20 mm and length over 20 mm indicates damage to the most significant trophic chains. The forest belt studied is in a highly disturbed condition, the plots being dominated by steppe species of herbaceous plants. The analyzed factors (diversity and extent of cover of herbaceous plants) do not determine the structure of the litter macrofauna community but affect it indirectly: a slight increase in the total number of invertebrates was observed in areas with minimal and maximum number of species of herbaceous plants. The relationship between the abundance of invertebrates and the percentage of herbaceous plant cover is manifested insignificantly. We noted a tendency for the number of invertebrate species to decrease along the gradient of herbaceous plant cover due to the concentration of dominant predatory species which exterminate other trophic groups of macrofauna.

Influence of Increasing Prosopis glandulosa on Herbaceous Diversity and Composition on Two Soils in Southern Mixed-Grass Prairie

We evaluate how increasing cover levels of the tree Prosopis glandulosa Torr. influence herbaceous species richness and composition in two soil-landscape positions in the mixed-grass prairie of the southern Great Plains, U.S.A. Herbaceous species biomass and composition and P. glandulosa cover were monitored on silt-loam bottomlands and clay-loam uplands, in spring, summer, and fall from 1995 to 2001 in 8 paddocks varying in size from 1,283 to 2,130 ha. P. glandulosa trees were closely associated with herbaceous plant composition and richness in different ways on each of the soils. Herbaceous species richness was greater on silt-loam bottoms than clay-loam uplands and decreased little except at the highest P. glandulosa cover levels on both soils. Herbaceous vegetation differed between soil sites and between low (<15%), mid (between 20 and 55%), and high (>60%) P. glandulosa cover levels. The greatest species richness on both soils occurred in areas dominated by herbaceous plants and the least at the highest levels of P. glandulosa cover. On both soils increasing P. glandulosa cover from 0 to 100% was associated with significant declines in herbaceous biomass with C4 tall grasses, C4 mid-grasses, and forbs, small declines with C4 short grasses, and significant increases with C3 annual grasses. Both cool and warm season forb herbaceous functional groups declined with increasing P. glandulosa cover. These results indicate that P. glandulosa reduction on the bottomland sites would yield the greatest benefits in species richness and herbage productivity.

The role of holm oak edges in the control of disturbance and conservation of plant diversity in fire-prone landscapes

Holm oak (Quercus rotundifolia) woodlands have been able to persist in fire-prone landscapes in northern Portugal where they seem to play a relevant role in community and landscape level patterns and processes, namely in the control of disturbance events and in the maintenance of biodiversity. In this research we tested the following hypotheses: (i) holm oak woodlands affect fire behavior, mainly by disrupting and delaying fire spread; (ii) disruption and delaying of fire spread is due to fire extinction at the edge of woodlands; and (iii) plant diversity is favored by frequent low-intensity fires as a result of the control of fire spread by holm oak woodland edges. We sampled herbaceous, shrub and tree structure and herbaceous plant composition across edges of holm oak woodlands with known recent contact with fire. Using BehavePlus we converted structural data into fuel models and simulated fire behavior for the locations sampled along the exterior–interior gradient of the woodlands. Our results indicate that holm oak woodlands play a relevant role in the control of fire spread and in the maintenance of plant diversity. We found differences in simulated maximum rate of fire spread (ROS) and fireline intensity (FLI) between outside and inside woodlands as well as a 100% probability of fire extinction when fuel moisture was >12% and wind speed at 10m aboveground was <40kmh−1, supporting the self-extinction hypothesis. We found also that richness and abundance of herbaceous plants varied between the interior and exterior of the woodland, with higher values outside the woodland, and that plant composition along the interior–exterior gradient had distinct patterns. These variables and the pattern of plant distribution were also significantly affected by time since last fire event. We conclude that holm oak woodlands affect fire behavior by interrupting fire spread at the edge zone and that fire-created edges affect herbaceous plant species richness, abundance and distribution by maintaining habitat diversity, which increased plant diversity at patch and landscape levels. Based on our results and other evidence, we developed a conceptual model of the dynamics of fire, landscape structure, and plant diversity in fire-prone landscapes where holm oak patches persist.

Long‐term effects of exclusion of grazing stock on degraded herbaceous plant communities in a riparian Eucalyptus camaldulensis forest in south‐eastern Australia

Abstract Stock grazing has degraded many riparian ecosystems around the world. However, the potential for ecosystem recovery following the removal of grazing stock is poorly known. We developed a conceptual model to predict the responses of native and exotic herbaceous plants to grazing exclusion, based on site productivity and the degree of initial vegetation degradation. The effects of excluding grazing stock on richness, cover and composition of herbaceous plants were examined over 12 years in the degraded understorey of a riparian forest in Gulpa Island State Forest in south‐eastern Australia. We predicted that grazing exclusion would lead to limited changes in vegetation cover, richness and composition, owing to presumed low site productivity and the high degree of understorey degradation. Results showed that the cover, richness and composition of native and exotic species varied significantly among years. Over all plots, regions and years, total cover was slightly but significantly lower in grazed than in ungrazed plots (43.4% vs. 50.8%). While the cover of native plants increased over time in both treatments, the rate of increase was slightly greater in ungrazed plots. Grazing exclusion had no effect on the richness of native or exotic species, but had a significant but minor impact on plant composition, with different common species (mostly exotics) being promoted or diminished in ungrazed plots. The composition of grazed and ungrazed areas did not become more different over time. Overall, the effects that could be attributed to grazing exclusion were relatively minor and transient. Results are consistent with predictions based on site productivity and initial degradation, and should not be extrapolated to other more productive, or less degraded, riparian systems.

The relative importance of cattle grazing in subtropical grasslands: does it reduce or enhance plant biodiversity?

Summary Livestock grazing enterprises have potentially threatening effects on the conservation of plants in grassy subtropical eucalypt woodlands. Commercial levels of grazing could cause local extinctions of sensitive native species and/or reductions in abundance and species richness in native pastures. We studied the nature of grazing impacts on the diversity and composition of herbaceous plants and used a natural experiment to analyse the effects of disturbances (cattle grazing, soil disturbance, water enrichment) and environment (lithology, slope position, presence of trees) on plant community composition in eastern Australia. We sampled pastures and reserves at 191 sites over an area of 3000 ha. Canonical correspondence analysis (CCA) was used to explore the relative importance of disturbance and environment in accounting for floristic variation and to examine individual species responses. From individual responses, we identified seven response groups relating to grazing. The factors analysed explained small but significant amounts of floristic variation, and there were interactions between soil disturbance, water enrichment and grazing. We explored the hypothesis that grazing increased species density at small scales but decreased it at landscape scales, due to the elimination of grazing‐sensitive species. Our data did not support the hypothesis, as there were similar numbers of species that increase with grazing (increasers) and species that decline with increasing grazing (decreasers) in the assemblage. However, there were more native decreasers and more exotic increasers in the assemblage. Synthesis and applications. For land managers to retain plant diversity on grazed landscapes, it would be desirable to provide all levels of grazing pressure across the landscape, including areas protected from livestock grazing. This would apply to all plant communities where both grazing increasers and decreasers are present. Extensive areas supporting grassland with a tall tussock structure that is selectively grazed are most important, as all plant response groups have some representation and ecosystem function is retained under moderate grazing. In terms of regional conservation planning, the protection and enlargement of areas protected from livestock grazing is important in the study area, as these occur on only about 4% of the landscape and are threatened by on‐going disturbances and land‐use intensification.

Rangeland Grasshoppers (Orthoptera: Acrididae) Associated with Mesquite and Juniper Habitats in the Texas Rolling Plains

Density, species composition, and spatial distribution of grasshoppers and biomass and species composition of herbaceous plants in 2 rangeland habitats, honey mesquite, Prosopis glandulosa Torrey, and redberry juniper, Juniperus pinchoti Sudworth, were quantified in the Texas Rolling Plains in 1992 and 1993. Grasshoppers were sampled weekly from early May to late September, and vegetation was sampled 3 times (May, July, and September). Grasshopper density was significantly greater in the mesquite habitat than in the juniper habitat for both years, with an average of 6.38 and 5.50 grasshoppers per square meter in mesquite habitat and 0.86 and 0.33 grasshoppers per square meter in juniper habitat in 1992 and 1993, respectively. Grasshopper species composition varied with sampling year and with the habitat, with significantly greater species diversity in mesquite habitat compared with that in the juniper habitat. Of the 37 species of grasshoppers captured during the 2-yr study, 3 species in the mesquite habitat, Hesperotettix speciosus (Scudder), Hesperotettix viridis (Thomas), and Syrbula admirabilis Uhler, and 2 species in the juniper habitat, Ageneotettix deorum (Scudder) and S. admirabilis , comprised ≍50% of the adult grasshoppers collected. Analysis of dispersion patterns of grasshoppers in 1-m2 transects showed that the grasshoppers exhibit a random spatial pattern in both habitats. Average herbaceous biomass for both years was greater in the mesquite (mean = 3,435 kg/h) than in the juniper (mean = 793 kg/h) habitat, with greater grass than forb biomass in both habitats. Grasshopper abundance and species composition in rangeland mesquite and juniper habitats appear to be related with the herbaceous plant community structure in those habitats.

Tracked Vehicle Impacts on Vegetation at the Pinon Canyon Maneuver Site, Colorado

AbstractThe effects of military tracked vehicle maneuvers on the vegetation of the Pinon Canyon Maneuver Site (PCMS), southeastern Colorado, were assessed from 1985 to 1987. Tracking decreased plant basal and litter cover and increased bare ground. The immediate effect of tracking was to reduce perennial warm‐season grasses [primarily blue grama, Bouteloua gracilis (H.B.K.) Lag. ex. Griffith] followed by the invasion of annual cool‐season grasses [sixweeks grass, Vulpia octoflora (Walt.) Rybd., and little barley, Hordeum pusillum Nutt.] and annual warm‐season forbs [sunflower, Helianthus annuus L., russian thistle, Salsola iberica Sennen &amp; Pau, and kochia, Kochia scoparia (L.) Schrab.]. In untracked areas, herbaceous plant composition did not change; however, litter increased and bare ground and basal cover decreased. Changes in cover in untracked areas was attributed to above average precipitation and the cessation of domestic livestock grazing. Overall (tracked plus untracked areas), total cover increased on PCMS, but the proportion of annual cover also increased. Woody plant density decreased an average of 9% from 1985 to 1987. Long‐term management of the soil and vegetative resources of PCMS are discussed.