Plant Communities In Field Research Articles

Intraspecific chemical variation of Tanacetum vulgare affects plant growth and reproductive traits in field plant communities.

The study investigated the impact of intraspecific plant chemodiversity on plant growth and reproductive traits at both the plant and plot levels. It also aimed to understand how chemodiversity at stand level affects ecosystem functioning and plant-plant interactions. We describe a biodiversity experiment in which we manipulated intraspecific plant chemodiversity at the plot level using six different chemotypes of common tansy (Tanacetum vulgare L., Asteraceae). We tested the effects of chemotype identity and plot-level chemotype richness on plant growth and reproductive traits and plot-level headspace emissions. The study found that plant chemotypes differed in growth and reproductive traits and that traits were affected by the chemotype richness of the plots. Although morphological differences among chemotypes became less pronounced over time, reproductive phenology patterns persisted. Plot-level trait means were also affected by the presence or absence of certain chemotypes in a plot, and the direction of the effect depended on the specific chemotype. However, chemotype richness did not lead to overyielding effects. Lastly, chemotype blends released from plant communities were neither richer nor more diverse with increasing plot-level chemotype richness, but became more dissimilar as they became more dissimilar in their leaf terpenoid profiles. We found that intraspecific plant chemodiversity is crucial in plant-plant interactions. We also found that the effects of chemodiversity on plant growth and reproductive traits were complex and varied depending on the chemotype richness of the plots. This long-term field experiment will allow further investigation into plant-insect interactions and insect community assembly in response to intraspecific chemodiversity.

Plant species capacity to drive soil fungal communities contributes to differential impacts of plant–soil legacies

Plant–soil feedbacks occur when plants alter soil conditions in ways that influence growth of subsequent plants. We explored the relative contributions of such legacy effects and contemporary interactions in a greenhouse experiment by crossing three soil microbial inocula conditioned by distinct field plant communities with two greenhouse plant treatments (Malva parviflora or Sonchus oleraceus). We evaluated the composition of inocula and final microbial communities after greenhouse cultivation and correlated compositional changes to plant growth. Final bacterial community composition reflected both field and greenhouse plant treatments, but was not associated with greenhouse plant growth. Alternatively, final fungal communities only reflected recent greenhouse plant exposures and were associated with plant growth, albeit differently for the two species. M. parviflora growth correlated with final, but not initial, fungal community composition. S. oleraceus growth correlated with the degree of change between initial and final fungal communities, but only in the highly growth‐suppressive inocula from plots conditioned by plants producing high levels of toxic secondary compounds. Thus, plant sensitivity to microbial legacies can be jointly determined by a plant species' ability to exert selective pressures and the remnant microbial community's responsiveness to plant interactions.

Characteristics of flora and segetal communities of the Landscape Park Pojezierze Iławskie

Smal part (1100 ha - 4,7 %) of the Landscape Park Pojezierze Iławskie is an agricultural area. On the arable soils of this area floristic and phytosociological studies of weed communities were performed. In total, 156 species of vascular plants were registered what makes 75 percent of the whole segetal population high diferentitation in field plants was found. Seven associations and three communities of segetal plants were distinguished. High quantitative participation of the field plant communities in the range of associations (72 percent studied areas) allows us to suggest that the degree of agrocenosis degradation is very small in this area as compare to the majority of the agricultural areas in Poland. Taking into account floristical and ecological diferentiation, geographical range and syntaksonomical position three assiociations (<i>Teesdaleo-Arnoseridetum minimae, Aphano-Matricarietum</i> and <i>Spergulo-Chrysanthemetum segeti</i>) present high specific value and deserve of the active form of protection.

Long-Term Data from Fields Recovering after Sugarcane, Banana, and Pasture Cultivation in Ecuador

I report here on an ongoing permanent plot study in areas recovering from agriculture in Ecuador. These plots were set up in 1995 at Maquipucuna Reserve where the forest is tropical lower montane. The study consists of replicate fields in three past crop types (Sugarcane, Banana, and Pasture) for a total of six fields. Each field was first divided into 25 continuous 2 m × 5 m subplots which together form a 10 m × 25 m plot with the longest side bordering the adjacent forest. Then starting in 1996, and continuing annually every year since, each subplot has been sampled for percent cover of all plants and diameter at breast height (dbh) for all trees whose dbh is greater than or equal to 1 cm. I have used that data in these published studies: (1) species composition and life form, richness, and basal area trends, (2) computation of all positive and negative pairwise species associations, (3) relationships between richness and productivity over time, (4) dominance-diversity curves, and (5) definition and quantification of old field plant communities. Finally with the help of the LTER program in Puerto Rico, this sampling continues, with 2012 marking the sixteenth year of continuous annual sampling.

Stubble field plant communities of the Mazowiecki Landscape Park

The characteristics of communities found in unploughed stubble fields of the Mazowiecki Landscape Park and its agricultural buffer zone are presented in the paper. The association <i>Echinochloo-Setarietum</i> divided into a typical variant, the variant with <i>Galinsoga parviflora</i>, and the variant with <i>Bidens tripartite</i>, was the most frequently noted and floristically differentiated association. Patches of <i>Digitarietum ischaemi</i> were also frequently observed in stubble fields on the poorest habitats. Rarely, on fertile soils, small patches of floristically rich communities with <i>Veronica agrestis</i> were recorded. Periodically, excessively wet habitats were seldom occupied by the speciesrichest phytocoenoses of <i>Centunculo-Anthoceretum punctati</i>. Single patches of the community with <i>Setaria pumila</i>, the form with <i>Aphanes arvensis</i>, were observed only in the south-eastern part of the Park.

Avena strigosa Schreb. in agrocoenoses of the Podlaski Przełom Bugu mesoregion

The research on the localities of <i>Avena strigosa</i> and on its increased occurrence in agricultural crops of the Podlaski Przełom Bugu was carried out in 1994-1998. The documentation of this research consists of 600 phytosociological relevés and the floristic records. The paper presents the composition and structure of the field plant communities where <i>Avena strigosa</i> was found. It occurs frequently on various soil types of the Podlaski Przełom Bugu. However, on the area examined it was found just in small numbers, covering up to 5% of the area, while in the eastern part of the area an increase in its occurrence was observed. In the area of the Podlaski Przełom Bugu <i>Avena strigosa</i> occurred in spring cereals in the communities of <i>Arnoserido</i>-<i>Scleranthetum</i> and <i>Vicietum tetraspermae</i> as well as in the poor field communities, with the character species of <i>Aperion spicae</i>-<i>venti</i> and <i>Panico</i>-<i>Setarion</i>. Additionally, <i>Avena strigosa</i> was also found in the field communities of root crops belonging to <i>Panico</i>-<i>Setarion</i> alliance; however, it was present there just in small numbers.

Generalization of heterogeneous alpine vegetation in air photo-based image classification, Latnjajaure catchment, northern Sweden

Mapping alpine vegetation at a meso-scale (catchment level) using remote sensing presents difficulties due to a patchy distribution and heterogeneous spectral appearance of the plant cover. We discuss issues of generalization and accuracy assessment in this case study when using a digital CIR air photo for an automatic classification of the dominant plant communities. Spectral information from an aerial photograph was supplemented by classified plant communities in field and by topographical information derived from a DEM. 150 control points were tracked in the field using a GPS. The outcome from three alternative classifications was analysed by Kappa statistics, user’s and producer’s accuracy. Overall accuracy did not differ between the classifications although producer’s and user’s accuracy for separate classes differed together with total surface (ha) and distribution. Manual accuracy assessment when recording the occurrence of the correct class within a radius of 5 meters from the control points generated an improvement of 16 % of the total accuracy. About 10 plant communities could be classified with acceptable accuracy where the chosen classification scheme determined the final outcome. If a high resolution pixel mosaic is generalized to units that match the positional accuracy of simple GPS this generalization may also influence the information content of the image.

Response of Tridens Flavus (l.) A. S. Hitchc. to Soil Nutrients and Disturbance in an Early Successional Old Field1

Soil nutrients and disturbance are two of the main abiotic factors that influence plant dominance (canopy cover), density, and fecundity in early successional old field plant communities. The manner in which the dominant species in old field successional systems respond to the interaction of nutrients and disturbance is poorly known. We examined the dominance, density of flowering tillers, and reproductive output of Tridens flavus, a perennial, warm-season bunchgrass that is important in old field succession, to varying soil nutrient and disturbance regimes. We tested the hypothesis that the interaction between nutrients and disturbance would influence the performance (cover, density, fecundity) of T. flavus. To test this hypothesis, we subjected 25 m2 experimental plots to various combinations of fertilizer and mowing treatments for eight years after initially plowing the field. The performance of T. flavus was measured by estimating percent cover for 8 years (1996–2003) and both density of flowering tillers and reproductive output (panicle length and number of branches per panicle) for three years (2001–2003). The pattern of canopy cover of T. flavus over the first eight years of succession varied over time depending on mowing regime. Dominance was significantly higher in plots that were fertilized only in years one and five than in annually fertilized and unfertilized control plots. The length of panicles and density of flowering tillers were both significantly greater in annually mowed plots than in unmowed plots. In the absence of mowing in particular, T. flavus became overtopped by woody species and declined in this old field community. Therefore, disturbances such as mowing and fertilization may be important in maintaining grasses such as Tridens flavus in old fields.

Mechanisms for Dominance in An Early Successional Old Field by the Invasive Non-Native Lespedeza Cuneata (Dum. Cours.) G. Don

Researchers studying invasive plants often concentrate their efforts on predictive models thought to allow invasive plants to dominate native landscapes. However, if an invasive is already well established then experimental research is necessary to provide the information necessary to effectively manage the species. Prescribing appropriate management strategies without prior experimental research may not only be ineffective but also may squander limited resources or have the unintended consequence of furthering spread. Lespedeza cuneata(Dum. Cours.) G. Don. is a well-established invasive plant of old fields and tall-grass prairie in the US. Managers suspect this species shades-out native plants and this is proposed as its primary mechanism for dominance. Using field experiments we tested probable factors allowing the species to establish itself and, once established, interfere in old field plant communities. We also examined the effects of two common anthropogenic disturbances (mowing and nutrients) on L. cuneata growth and establishment. When L. cuneata was treated (clipping, herbicide and stem pull-back) there was a significant increase in species richness and native species cover. Stem density and canopy cover of L. cuneata increased significantly with mowing frequency but decreased with nutrient input. We suggest that mowing benefits L. cuneata while also hindering woody competition. Results also indicate L. cuneata is less prevalent on nutrient enriched soils than on unamended soil. Lespedeza cuneata appears to suppress native plants by shading them out and it can subsequently take over grassland communities. Since it has a varying response to human induced disturbances and may actually benefit from mowing, land managers should be cautious when utilizing this as a management tool.

Succession in Old‐Field Plant Communities: Effects of Contrasting Types of Nutrient Enrichment

We investigated the effects of monthly nutrient applications on succession in two old—field plant communities. Succession was monitored for 3 yr in 1—yr (younger) and 4—yr (older) experimental plots. Three 0.1—ha plots in each old field were treated with sludge, three with fertilizer, and two were left as untreated controls. In the younger community, herbaceous perennials and winter annuals replaced summer annuals by the 3rd yr of succession in control plots. Summer annuals, however, dominated enriched plots throughout the study. Species richness was significantly higher in enriched plots than in control plots during the 1st yr, but was significantly lower than control plots thereafter. Annual aboveground net primary productivity (ANPP) was significantly greater in enriched plots than in controls in the 1st yr, but the converse occurred in the 3rd yr. The type of nutrient enrichment affected ANPP; sludge plots had significantly lower ANPP than fertilizer plots in the 1st and 3rd yr. In the older community, two summer annuals and a biennial displaced dominant perennial grasses in enriched plots. In contrast to the younger community, ANPP was consistently greater in nutrient—enriched plots than in controls, and nutrient enrichment did not alter species richness. The type of nutrient enrichment affected the older community in an opposite manner from the younger community; sludge plots had significantly greater ANPP than fertilizer plots in the 3rd yr. We concluded that the age and physiognomy of the old—field community, the type of nutrients applied, and the duration of enrichment, each influenced the course of succession; responses observed in the 1st yr of enrichment were not indicative of later trends.

Effects of chronic gamma irradiation on the development of old field plant communities

First- and second-year old field plant communities were allowed to develop in sections of the Gamma Radiation Field at Brookhaven National Laboratory. The communities developing under irradiation differed in general from non-irradiated communities in lower diversity of species, in lower total plant cover, and in the densities of individual species. Changes in species composition of the communities along the radiation gradient were proportional to the daily radiation exposure, a 50 per cent reduction in the coefficient of community corresponding to an approximately 3-fold change in radiation exposure rate. While there was an overall decline in total density along the gradient of increasing radiation, densities of individual species varied greatly without simple relationship to radiation exposure. Individual plants in the irradiated communities differed in form and in reproductive potential from those in non-irradiated communities. At exposures in excess of 320 r/day growth of most species was inhibited and anomalies in form were common. The reproductive potential of Erigeron canadensis, one of the relatively resistant species of the second year communities, was zero at exposures of 320 r/day and above, although individual plants survived 640 r/day. This work shows: (1) that any threshold for effects of radiation on species composition of old field communities lies at less than 50 r/day; (2) changes in species composition are approximately linearly related to the logarithm of daily radiation exposure; (3) the principle of species individuality appears to apply to communities exposed to ionizing radiation as it does to communities along other environmental gradients ; (4) the individuality of species' responses to radiation results in a different community at each radiation exposure; (5) all the higher plants of the old field communities in this study are relatively radioresistant; (6) resistance is correlated in these field studies with low average interphase chromosome volumes and with relatively high degrees of polyploidy; (7) using the effects of irradiation on the reproductive capacity of Erigeron as an example, sexual reproduction remains substantially intact at exposures as high as 1/6–1/3 those required to exclude the species from the community: reduced quantities of viable seeds are produced at exposures about 1/2 those which excluded the species; (8) there is at present no clear relationship between the LD 50's of laboratory studies and criteria useful in appraising effects on communities.

Hydrologic Characteristics of Three Soils Supporting Natural Hardwoods, Planted Red Pine, and Old Field Plant Communities

An investigation conducted during 1958 to 1961 compared hydrologic characteristics of the Hagerstown, Calvin-Edom, and Dekalb soils under natural hardwoods, planted red pine, and old field plant communities. Infiltration of simulated rainfall, water percolation, and soil properties were investigated. Other than surface organic matter accumulations and rooting habits, there were no significant differences in physical properties of soil profiles under old field and red pine cover. Hardwood soil profiles differed materially from old field and red pine soil profiles, with organic matter, porosity, and water-stable aggregates being higher and bulk density lower in the upper horizons under hardwoods. Average wet-run infiltration capacity was 33% higher under red pine than under old field cover, while infiltration under hardwoods exceeded that under red pine by only 7%. Infiltration was less variable under red pine and hardwoods than under old field cover. Vegetational influences affecting water percolation were exerted primarily through their effect on soil porosity. Noncapillary porosity was more closely related to variations in soil permeability than were total porosity or aggregate stability.