Endophytic bacteria are critical for plant growth and health. However, compositional and functional responses of bacterial endophyte communities towards agricultural practices are still poorly ...understood. Hence, we analyzed the influence of fertilizer application and mowing frequency on bacterial endophytes in three agriculturally important grass species. For this purpose, we examined bacterial endophytic communities in aerial plant parts of Dactylis glomerata L., Festuca rubra L., and Lolium perenne L. by pyrotag sequencing of bacterial 16S rRNA genes over two consecutive years. Although management regimes influenced endophyte communities, observed responses were grass species-specific. This might be attributed to several bacteria specifically associated with a single grass species. We further predicted functional profiles from obtained 16S rRNA data. These profiles revealed that predicted abundances of genes involved in plant growth promotion or nitrogen metabolism differed between grass species and between management regimes. Moreover, structural and functional community patterns showed no correlation to each other indicating that plant species-specific selection of endophytes is driven by functional rather than phylogenetic traits. The unique combination of 16S rRNA data and functional profiles provided a holistic picture of compositional and functional responses of bacterial endophytes in agricultural relevant grass species towards management practices.
•Native species in ponderosa pine woodland are resistant to moderate grazing after summer wildfire.•Total herbaceous productivity is resistant to moderate grazing after summer wildfire.•Moderate ...grazing after summer wildfire reduced old dead material and increased richness.•Early growing season defoliation reduces non-native annual grasses.•Early growing season defoliation increases native diversity.
There remains a high level of ambiguity around post-fire grazing management. The Lodgepole Complex fire burned 109,346 ha in east-central Montana in July 2017, including areas previously burned in 2003 by the Bureau of Land Management for fuels mitigation. We hypothesized that herbaceous productivity and species composition in ponderosa pine woodlands are resistant to moderate grazing and timing of defoliation the first growing season after fire. Eight exclosures (25 × 15 m) were built, 4 on reburned area and 4 on wildfire area. To determine grazing effects, a 15 × 10 m sampling area in each exclosure was paired with a grazed section outside the exclosure. Additionally, four 5x10-m plots were established within each exclosure and were mowed to 10 cm in June, July, August, or not mowed to determine seasonal defoliation effects. Differences between grazed and nongrazed sites in 2019 were limited. There was a trend for less old dead biomass in grazed than nongrazed treatments. Species richness was greater on grazed sites than nongrazed or reburn sites. Native species richness was greater on grazed sites than nongrazed sites and reburn sites had an intermediate level of native species richness. Standing crop was reduced by defoliation, with current year and perennial grass biomass being unaffected. The reduction in standing crop was driven by less old dead biomass on defoliated plots. June defoliation reduced C3 grasses and increased C4 grasses, and June and July defoliation each reduced annual grasses. Simpson’s and native Simpson’s diversity were greater on defoliated plots. Results indicate ponderosa pine woodland is resilient to moderate post-fire grazing.
A complicated life history and specific habitat requirements make the Alcon blue butterfly
Phengaris alcon
a very sensitive species to land-use change. Eggs are oviposited on some
Gentiana
and
...Gentianella
plants, in whose flowerheads larvae initially feed, after which they continue their development as social parasites in the nests of specific
Myrmica
ants, once they have been adopted by workers. One of the main threats to their existence is mowing at a time when most individuals are still on gentians. In our research, we tested an emergency conservation method on a site of the butterfly subjected to this kind of pressure in the Białowieża Forest (NE Poland). Previous studies showed that the focal population (dependent on
Gentiana pneumonanthe
and
Myrmica scabrinodis
) was characterized by an extremely high density of adults as well as of
Ichneumon eumerus
, i.e. the rare and specific parasitoid of
P. alcon
. In mid-August 2020 we performed an unplanned experiment to save caterpillars present in freshly cut plants. We selected about 1800 shoots bearing the eggs or egg shells of the butterfly. Seven hundred and fifty preadoption larvae were transported to the site and placed close to the nests of host ants located in patches without
G. pneumonanthe
. In the following season we observed that the
P. alcon
infestation rate of experimental colonies was similar to a control patch, and proportions of parasited pupae did not differ, either.
Implications for conservation.
Our experiment proved that such actions can be highly effective as emergency conservation methods, and possibly also in (re)introductions of
P. alcon
.
Returning turfgrass clippings to soil (i.e., mulching) has been shown to yield many benefits, such as reducing fertilizer requirements. However, previous reports on the contribution of clippings to ...turfgrass fertilization varies widely, making it difficult for turfgrass managers to adjust their fertilization practices. Other potential benefits of this practice, such as soil water conservation, still need to be quantified. The objectives of this project were to measure the contribution of Kentucky bluegrass clippings to N, P and K fertilization under four different N levels and to measure the impact of clippings management on turfgrass color (NDVI), soil nutrient and water content as well as thatch accumulation. A field experiment was conducted over three years, with treatments consisting of two clipping management strategies (returned or removed) and four nitrogen levels (0, 48, 96 and 144 kg N ha −1 yr −1). Clippings were collected on every mowing date and were analyzed for N, P and K foliar content. Soil volumetric water content and NDVI were measured weekly, while thatch accumulation and soil chemical content (Mehlich-3) were assessed twice per year. Increasing N fertilization resulted in an increase in both clippings dry matter yield (DMY) and foliar N concentration. Returning grass clippings was equivalent to doubling the amount of N applied through the fertilizer and resulted in an increase in turfgrass color and soil P and K levels. For P and K, clippings contribution was more affected by their DMY than by foliar concentrations. Grass clippings did not contribute to thatch accumulation, but resulted in a consistent increase (3.9% on average) in soil volumetric water content.
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•Grass clippings contribution to lawn fertilization is affected by nitrogen application rate.•Increasing the N rate increases dry matter yield, turfgrass color and clippings content in N, P and K.•Returning grass clippings is equivalent to doubling the amount of N applied.•Soil volumetric water content is 4% higher, on average, when clippings are returned.
The increased availability of systematically acquired high spatial and temporal resolution optical imagery improves the characterization of dynamic land surface processes such as agriculture. The use ...of time series phenology can help overcome limitations of conventional classification-based mapping approaches encountered when, for example, attempting to characterize grassland use intensity. In Europe, permanent grasslands account for more than one third of all agricultural land and a considerable share of the EU Common Agricultural Policy (CAP) budget is devoted to grasslands. The frequency and timing of mowing events is an important proxy for grassland use intensity and methods that allow characterizing grassland use intensity at the parcel level and over large areas are urgently needed. Here we present a novel algorithm that allows detecting and quantifying the number and timing of mowing events in central European grasslands. The algorithm utilizes all imagery acquired by Sentinel-2 MSI and Landsat-8 OLI for one entire year as available from the NASA Harmonized Landsat-Sentinel dataset. Cloud-free observations from both sensors are first synthesized through compositing at 10-day interval. Machine learning algorithms are then used to derive a grassland stratum. The intra-annual growing season profiles of NDVI values are subsequently assessed and compared to an idealized growing season trajectory. Residuals between the idealized trajectory and a polynomial model fit to the observed NDVI values are then evaluated to detect potential mowing events. We demonstrate and evaluate the performance of our algorithm and utilize its large area analysis capabilities by mapping the frequency and timing of grassland mowing events in 2016 on the national-scale across Germany. Our results suggest that 25% of the grassland area is not used for mowing. Validation results however suggest a relatively high omission error of the algorithm for areas that only experienced a single mowing event. The date ranges of detected mowing events compare overall well to a sample of interpreted time series points and to farm level reports on mowing dates. The mapped mowing patterns depict typical management regimes across Germany. Overall, our results exemplify the value of multi-sensor time series applications for characterizing land use intensity across large areas.
•Current EO data sources provide unprecedented temporal data at parcel level detail.•Opportunity for improved characterization of large-area grassland management•Novel approach exploits phenology signal from integrated S2 & L8 time series.•Algorithm presented and first national scale assessment for Germany performed.•Approach is sensitive to parcel level mowing regimes, regional insights provided.
Backgrounds and aims
Mowing and P-fertilization enhance legume seedling establishment, assisting in successful restoration of degraded grasslands. Legume establishment may influence soil chemical ...compounds and soil microbial assemblage to facilitate legume productivity. We aim to better understand these complex plant-soil-microbial interactions to improve grassland productivity following overgrazing.
Methods
We conducted a 3-years
Medicago falcata
reseeding experiment was in semi-arid meadows, assessing responses of aboveground plant biomass, soil chemical compounds, and soil microbial community composition. Reseeded plots were mowed and/or P-fertilized.
Results
Application of both management practices increased grassland biomass compared with all other combinations. Soil chemical diversity predicted fungal alpha diversity, and fungal alpha diversity positively correlated with aboveground biomass. Our results indicate reseeded alfalfa directly altered bulk soil chemical compounds with subsequent alterations in grassland microbial communities. Soils contained chemical compounds with antifungal properties that indirectly improved grassland productivity via antagonism to pathogenic fungi. Furthermore, we found three specific compounds (5-methyltridecane, pentatriacontane, and N-tridecane) reduced microbial diversity.
Conclusions
Here we demonstrate soil chemical compounds play an important role in shaping beneficial microbial communities to improve grassland biomass. These results may help direct beneficial soil microbial community composition through improved grassland management practices.
Grasslands cover one third of the earth’s terrestrial surface and are mainly used for livestock production. The usage type, use intensity and condition of grasslands are often unclear. Remote sensing ...enables the analysis of grassland production and management on large spatial scales and with high temporal resolution. Despite growing numbers of studies in the field, remote sensing applications in grassland biomes are underrepresented in literature and less streamlined compared to other vegetation types. By reviewing articles within research on satellite-based remote sensing of grassland production traits and management, we describe and evaluate methods and results and reveal spatial and temporal patterns of existing work. In addition, we highlight research gaps and suggest research opportunities. The focus is on managed grasslands and pastures and special emphasize is given to the assessment of studies on grazing intensity and mowing detection based on earth observation data. Grazing and mowing highly influence the production and ecology of grassland and are major grassland management types. In total, 253 research articles were reviewed. The majority of these studies focused on grassland production traits and only 80 articles were about grassland management and use intensity. While the remote sensing-based analysis of grassland production heavily relied on empirical relationships between ground-truth and satellite data or radiation transfer models, the used methods to detect and investigate grassland management differed. In addition, this review identified that studies on grassland production traits with satellite data often lacked including spatial management information into the analyses. Studies focusing on grassland management and use intensity mostly investigated rather small study areas with homogeneous intensity levels among the grassland parcels. Combining grassland production estimations with management information, while accounting for the variability among grasslands, is recommended to facilitate the development of large-scale continuous monitoring and remote sensing grassland products, which have been rare thus far.
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