Herbaceous Stands Research Articles

Yield of yellow-flowered alfalfa (Medicago falcata L.) with the use of the growth regulator Albit, the microbiological fertilizer Sporion and molybdenum microfertilizer

Field studies were conducted at the Field Experimental Station of the Russian State Agricultural Academy named after K.A. Timiryazev (Moscow) in 2022-2024, the effect of the growth regulator Albit, microbiological fertilizer Sporion and molybdenum micronutrient on the formation of herbaceous stands of alfalfa of the sickle variety Nizhegorodskaya, alfalfa of the variable varieties Agnia and Taisia was studied. It was found that on medium-cultivated sod-podzolic soil with a pHKCl of 5,4, sickle-shaped alfalfa and variable alfalfa formed dense and weed-free agrophytocenoses. The density of sickle alfalfa in the 3rd year of life was 804-1051 shoots per 1m2, and variable alfalfa was significantly less - 712-947. There was no thinning of grass stands. The participation of variable alfalfa in the harvest for the third year by mowing was 80,5-99,9%, and sickle alfalfa 81,1-97,9%. Sickle alfalfa of the Nizhegorodskaya variety was characterized by high yields, providing an average of 6,4-6,78 t/ha of dry matter over three years. It increased the yield when using Albit, Sporion and molybdenum by 0,25; 0,37 and 0,38 t/ha, respectively.

Gravel Bar Vegetation Database

For the purpose of an ongoing research project dealing with the classification of European river gravel bar vegetation, we collected and digitized vegetation plot data included in the Gravel Bar Vegetation Database (GIVD ID: EU-00-025, http://www.givd.info/ID/EU-00-025). The database consists of vegetation plots obtained from the literature and from our own field sampling in the countries where this vegetation has not previously been studied or is less explored, especially in southeastern and northern Europe and the Caucasus. The database currently contains 1,738 vegetation plots from 18 countries representing different types and successional stages in the range of gravel bar vegetation from the initial herbaceous stands to scrub, mainly of the order Epilobietalia fleischeri (class Thlaspietea rotundifolii) and the class Salicetea purpureae. Geographical coordinates are available for all plots; accuracy of those derived from the literature depends on the precision of the location descriptions. European montane and submontane gravel-bed rivers with their typical vegetation belong to most endangered habitats; thus the database should complete the information about their distribution and their typical vegetation types. It also serves as data source for studies of vegetation structure and dynamics. The database is managed by the Vegetation Science Group at the Department of Botany and Zoology, Masaryk University, Brno. It has been integrated in the European Vegetation Archive (EVA).

Leaf-level nitrogen use efficiency: definition and importance

Nitrogen use efficiency (NUE) has been widely used to study the relationship between nitrogen uptake and dry mass production in the plant. As a subsystem of plant nitrogen use efficiency (NUE), I have defined leaf-level NUE as the surplus production (gross production minus leaf respiration) per unit amount of nitrogen allocated to the leaf, with factorization into leaf nitrogen productivity (NP) and mean residence time of leaf nitrogen (MRT). These concepts were applied to two herbaceous stands: a perennial Solidago altissima stand and an annual Amaranthus patulus stand. S. altissima had more than three times higher leaf NUE than A. patulus due to nearly three times longer MRT of leaf N. In both species, NUE and NP were higher at the leaf level than at the plant level, because most leaf N is involved directly in the photosynthetic activity and because leaf surplus production is higher than the plant net production. MRT was longer at the plant level. The more than twice as long MRT at the plant level as at the leaf level in S. altissima was due to a large contribution of nitrogen storage belowground in the winter in this species. Thus, comparisons between a perennial and an annual system and between plant- and leaf-level NUE with their components revealed the importance of N allocation, storage, recycling, and turnover of organs for leaf photosynthetic production and plant dry mass growth.

Productivity and botanical composition of herbaceous stands of different ages under agrolandscape conditions

The spatiotemporal dynamics of productivity and botanical composition of herbaceous grass-legume stands within an agrolandscape of a moraine hill are studied. The characteristics of the change in the energy value of the fodder being produced are revealed. Recommendations on adapting meadow fodder production to the landscape conditions are given.

Differential impacts of plant interactions on herbaceous species recruitment: disentangling factors controlling emergence, survival and growth of seedlings

Recruitment is a crucial event in the plant life cycle that is very sensitive to interaction with established vegetation. Based on a large comparative experiment, we tested the hypothesis that the components of recruitment--emergence time and rate, seedling survival and biomass--differ in response to plant-plant interactions during recruitment. The consequences for the population are predicted with a simple demographic model assessing the response of seed production. In a common garden experiment, we recorded the recruitment of four target species in an individual-based survey protocol. A total of 7,680 seeds were sown within 20 neighbourhoods, consisting of 19 mono-specific herbaceous stands and a control treatment without vegetation. We measured transmitted light, temperature and moisture at soil surface to characterise the environmental conditions within neighbourhoods. The mean height of neighbours controlled temperature buffering and light interception and thus depicted the interaction gradient. Emergence rate and time increased with neighbour height in two of the four target species, while seedling survival and biomass significantly decreased with neighbour height in three and all four target species, respectively. We recorded a shift in seedling neighbour interactions under the tallest neighbours that largely favoured emergence but strongly depressed seedling survival and biomass. The components of recruitment were predicted to differ in their impact on later adult performance. Biomass strongly contributed to predicted seed production in three target species, and emergence had an equal or greater impact on a fourth species. These results confirm the fundamental role of plant-plant interactions in the recruitment of herbaceous species through a complex combination of habitat amelioration, which facilitates emergence and light competition, which in turn limits seedling survival and biomass.

Productivity of herbaceous stands of different ages under landscape conditions of a terminal moraine ridge

Yield formation of uneven-aged herbaceous stands under various weather and lanscape conditions is investigated in a multifactor experiment. It is shown that yield and adaptive properties of the stands depend in many respects on their age and climatic situation as well as on the properties of the landscape and soil environment.

Essai préliminaire de détection des champs d'ambroisie par télédétection spatiale

The detection of dense populations of ragweed ( Ambrosia artemisiifolia L.) using spatial remote sensing methods seems possible. A sufficiently accurate map of parcels of land infested with ragweed could offer new possibilities to engage in weeding campaigns and to appreciate the space-time evolution of this plant. Obviously, the main difficulties in this approach are related to the heterogeneous floral composition of herbaceous stands and to the risk of confusion of the spectral composition of ragweed with that of other species. On 21 July 2001, we carried out field surveys in zones with abundant ragweed near Lyon (Department of the Rhone), and we used the resulting data in connection with two images of the same area obtained by the Terra ASTER 1B satellite on 26 June and 13 August 2001. A measurement was made in the laboratory on a sample of the plant obtained from the same area to determine its reflectance spectrum. On analysis of the spatial images, we were able to localize herbaceous patches in which ragweed is dominant. When the density of this plant decreases, the reflectance signals of the populations become multiform, requiring further studies. Further progress can be expected when sensors such as the spatial tel IKONOS (operating at a resolution in the order of 1 to 5 m) or the future SPOT 5 (operating at a resolution of 2 to 3 m in the panchromatic mode or at 10 m in a multispectral mode) will be used, allowing us to work at a resolution on the order of one meter.

A review of soil erosion potential associated with biomass crops

It has been estimated that up to 60 million hectares could be devoted to energy crop production in the U.S. Due to economic considerations, biomass crops will probably be produced on marginal cropland which is frequently highly erodible. Thus, the impact of herbaceous and woody biomass crop production on soil erosion must be addressed. Perennial grasses provide year-round soil cover, limiting erosion even with continued biomass harvest. Vigorous perennial herbaceous stands reduce water runoff and sediment loss and favor soil development processes by improving soil organic matter, soil structure and soil water and nutrient-holding capacity. Minimum tillage management of row crops reduces erosion compared with systems involving more frequent or more extensive tillage. Woody biomass plantations reduce water erosion by improving water infiltration, reducing impacts by water droplets, intercepting rain and snow and physically stabilizing soil by their roots and leaf litter. Shelterbelts reduce wind erosion when planted as shelterbelts and improve soil organic matter, soil structure and soil moisture in their leeward zone, reducing soil erodibility. Harvesting of woody biomass plantations may be accompanied by increased erosion. Forestry clear-cutting, especially on steep slopes, often results in a large increase in water erosion. For this reason, it is essential that woody biomass plantations be designed for rotational harvesting, even though this may result in higher harvesting costs.

Leaf nitrogen distribution and whole canopy photosynthetic carbon gain in herbaceous stands

The amount of photosynthetically-active photon flux density incident upon a leaf and the nitrogen content of that leaf strongly affect the photosynthetic carbon gain of that leaf. Therefore, the canopy structure of a stand, affecting the light climate in the canopy, and the leaf nitrogen distribution pattern in the canopy, affect the carbon gain of the whole canopy. This review discusses the results of studies directed to this problem and obtained so far in open and in dense canopies of stands of herbaceous, monocotyledonous or dicotyledonous, plants in their growing or flowering stages. It is found that the leaf nitrogen distribution pattern in the canopy is vertically non-uniform, and in dense stands more strongly so than in open stands. The leaf nitrogen distribution pattern in most canopies closely approaches an optimal pattern in that it maximizes whole canopy potential carbon gain as calculated for the actual total leaf nitrogen content and leaf area index of the stand. The resulting increase in potential carbon gain as compared to a uniform leaf nitrogen distribution pattern is considerable and it is larger in dense stands than in open stands. For at least some dense stands simulation studies show that with the available total leaf nitrogen content, whole canopy carbon gains could still be considerable higher had a lower leaf area index been developed.

Size spectra of particulate matter in herbaceous stands

Particle-size spectra were obtained for three types of herbaceous stands subdivided into structural components. In spite of the remarkable non-uniformity, apparently caused by a number of uncontrollable factors influencing conditions in the stand (mainly meteorological episodes), clustering seemed to follow a certain trend. It was noteworthy that clustering occurred more frequently in samples collected on the same day than in samples of a similar kind. This may be interpreted in terms of the turnover rate of the deposit increased by translocation flows, and of the influence of the weather before sampling.

Forage Quality Responses of Selected Grasses to Tebuthiuron

Tebuthiuron pellets (20% active ingredient [a.i.]) applied at 0.6, 1.1 or 2.2 kg/ha (a.i.) to native stands of little bluestem and at 1.1 or 2.2 kg/ha to l-year-old seeded stands of Bahiagrass, Bell rhodesgrass, green sprangletop, and little bluestem did not significantly alter the in vitro digestible organic matter concentrations of grass leaves. Leaf water concentrations of Bahiagrass, green sprangletop, and little bluestem were not consistently altered by application of tebuthiuron. However, application of 1.1 or 2.2 kg/ha of tebuthiuron pellets to seeded stands or to native little bluestem increased foliar crude protein concentrations. Application of 0.125,0.188, or 0.25 ppm of tebuthiuron in aqueous solutions to pots containing grasses in the greenhouse significantly increased foliar crude protein concentrations, compared to that of untreated plants. Crude protein concentrations were increased only during the growing season of application in the native stand of little bluestem. These results suggest application of tebuthiuron for brush control may enhance rangeland forage crude protein concentrations while not affecting in vitro digestible organic matter. Research on herbicides for brush management traditionally has emphasized efficacy as related to dosage and time of application with lesser emphasis on forage responses. Most studies of range forage responses to herbicide application have evaluated changes in standing crop and botanical composition of herbaceous stands as attributed to selective removal or suppression of associated woody species. However, sublethal applications of some herbicides may significantly alter various physiological processes within some forage species (Reis 1976). Nutritional constituents, such as crude protein, have increased following applications of simazine [2chloro-4,y-bis(ethylamino)-s-triazine] (Allinson and Peters 1970) or atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-~-triazine] (Raker et al. 1980). The physiological mode of action of tebuthiuron [N-(5-(1 ,Idime

Autoradiography for Studying Individual Root Systems in Mixed Herbaceous Stands

Study of the morphology of individual root systems growing with those of associated plants is facilitated by washing a monolith of soil containing roots of plants whose tops were treated with C14 applied as urea. The roots thus extracted are pressed and dried. X—ray film is applied and the labeled roots can be detected clearly on the resulting autograph. A method of measuring root length for quantitative analysis is suggested.

THE CHLOROPHYLL CONTENT OF SOME NATIVE AND MANAGED PLANT COMMUNITIES IN CENTRAL MINNESOTA

Concentration of chlorophyll per unit area of land surface was measured for six forests and 13 native and managed herbaceous stands in central Minnesota. Chlorophyll samples were extracted in acetone and in ethyl ether, and spectro-photometric analysis made of chlorophyll a and b content. Wet and ovendry weights of the aboveground crop were determined.A highly significant correlation was found between the dry weight of the aboveground crop of the annual herbaceous stands and the chlorophyll content of these stands. All stable natural herbaceous stands had an approximately similar ratio of chlorophyll to the dry weight of aboveground parts.Chlorophyll content in grams per square meter of land surface along an upland gradient from field crop through native communities of increasing age or successional development or both was Zea mays (2.7), Soja max (0.9), younger to older successional stages of old field (0.3 to 0.6), native prairie (0.7), xeric (more open) savanna (0.6), mesic (less open) savanna (1.0), conifer–hardwood forest (3.1). Chlorophyll content for a pond hydrosere from the Nymphaea odorata margin through Carex lasiocarpa mat to Chamaedaphne calyculata shrub and Larix laricina forest increased from 0.3 to 1.4 g/m2. Values for a younger and older Populus tremuloides lowland grove were 1.7 and 5.9 and for a Typha marsh were 4.6 g/m2.These data showed a tendency for later successional stages to exceed earlier stages, for some lowland stands to exceed upland stands, for forest to exceed herbaceous communities on a given moisture level, and for field crops to exceed prairie and old field. The upland old field to forest sequence and the lowland Nymphaea to Larix sequence had similar chlorophyll contents for a given stage of successional development. There was a highly significant positive correlation between chlorophyll content and height of the arboreal stands, and a significant positive correlation between chlorophyll content and herbaceous stand height.A significant difference in chlorophyll content was found between all stands with three or more sample plots, except those with closely correspondent mean values. The maximum difference between stands was twentyfold, which does not support previous studies which have suggested a similarity of chlorophyll content in diverse communities.Chlorophyll concentrations and wet and dry weights per various plant parts are presented for the seven tree samples, and the presence of chlorophyll in other than leaf parts emphasized.