Single- versus Double-Species Cover Crop Effects on Soil Health and Yield in Mississippi Soybean Fields

Conservation management practices can improve soil health while minimizing deleterious effects of agriculture on the environment. However, adoption of these practices, particularly cover crops, is not widespread, as they often reduce crop yields compared to traditional management practices. The purpose of the current study was to determine if a two-species cover crop treatment of rye (Secale cereale L.) and crimson clover (Trifolium incarnatum L.) could increase soil health parameters and maximize soybean (Glycine max L.) yield greater than rye only in tilled and no-till Mississippi field soils. Enhanced microbial biomass and organic matter input from cover crops increased the activities of β-glucosidase, cellobiohydrolase, fluorescein diacetate hydrolysis, N-acetylglucosaminidase, and phosphatase in surface soils. Rye plus clover tended to elicit higher activities than rye only in no-till plots. Both cover crop treatments inhibited soybean yield in tilled plots by 11–25%. These results indicate that tillage exacerbates yield inhibition by cover crops in soybean and that double-species cover crop treatments were more consistent in increasing activities linked to nutrient cycling. Further study examining different combinations of cover crops in no-till systems is necessary to gain a better understanding of how they can be implemented to enhance soil health while maximizing crop yield.

Weed Suppression, Biomass and Nitrogen Accumulation in Mixed-Species and Single-Species Cover Crops in a Tropical Sugarcane Fallow

While mixed-species cover crops are gaining worldwide popularity, their utility in the ‘plough-out’ period in tropical sugar cane systems has not been investigated. Field trials investigating weed suppression (one season only), biomass production and nitrogen accumulation of single-species and mixed-species cover crops were conducted over two seasons on a commercial sugarcane farm in the Australian tropics. Mixed-species cover crops showed strong weed suppression, and were among the top treatments for biomass production each year, but did not yield the highest biomass in either season. Sunn hemp (Crotalaria juncea cv. Global sunn) produced the most biomass in the drier-than-average 2016–2017 season (>10 t dry matter ha−1), while soybean (Glycine max cv. Leichardt) produced the most biomass (5.3 t dry matter ha−1) in the wetter-than-average 2018–2019 season, highlighting the influence of seasonal conditions on species’ biomass production. The inclusion of multiple species in a short-term cover crop in the tropics where extreme weather events can occur can thus be seen as a risk mitigation strategy given the risk of failure of any given species in a given season.

Diversity and composition of moss guilds on uprooted trees in Central European mountain forests: effects of uprooting components and environmental variables

Key message The size of the structural components of the root–pit–mound complex was crucial for high moss species richness. Root plates, pits, and mounds were similar in terms of moss species composition, which was mostly determined by forest type. Context Uprooted trees may be colonized by different terricolous mosses including common species and specialists. Aims The main aim of the present study was to analyze the relative effects of tree uprooting on mosses. Methods We used the parametric ZIGLMM and GLMM models to explain the richness and abundance of the moss species and double constrained correspondence analysis (dc-CA) to analyze species composition. Results The size of components of RPM complexes had a positive effect on moss species richness. The species cover of mosses was positively correlated with elevation. Species richness was partly dependent on forest type and species cover on component type and age of the RPM complex. The most important factor diversifying species composition was the type of forest. Species traits were also related to forest communities. Conclusion Uprooted trees are worth keeping in forest community, especially large ones. Moreover, the conservation value of uprooted trees in woodlands is higher if they are dispersed in different forest types.

Grazing exclosures reveal divergent patterns of change in bunchgrass grasslands of Western Canada

Thirty-six long-term (14–83 years) cattle grazing exclosures and adjacent grazed pastures spanning a climatic gradient from cooler–wetter to warmer–drier growing seasons in south-central British Columbia were compared for temporal vegetation change. Trajectories of temporal vegetation change from non-metric multidimensional scaling were mostly scattered for the grazed areas, but more directed toward the dominant grasses, primarily rough fescue (Festuca campestris) or Kentucky bluegrass (Poa pratensis), for the exclosures. Plant community differences, detected only after 10 years of grazing exclusion, were primarily due to structural shifts in overall species cover related to growth increases of the dominant grasses inside exclosures. Species richness remained unchanged between the first and last sampling dates in both grazed areas and exclosures, with both treatments showing moderate degrees (15%–30%) of turnover in species composition. Shannon diversity declined in both treatments as a result of the structural changes in species cover. The results highlight the value of repeated monitoring of long-term exclosures for assessment of grassland resiliency to grazing. Further studies of the interaction of grazing and climate are needed for a more complete understanding of the ongoing vegetation change.

An uphill battle? The elevational distribution of alien plant species along rivers and roads in the Austrian Alps

Ever-increasing international trade and anthropogenic activity has led to the relocation of thousands of plant species worldwide. So far, the harsh climate of the European Alps historically has restricted the establishment of alien plants. However, new opportunities created by rising temperatures and increasing human activity might allow alien plants to spread further upwards. Here, the distribution of alien plants along an altitudinal gradient in two Austrian valleys is analyzed. Specifically, the distribution along two contrasting corridors (roads, rivers) and the spread of alien plants into adjacent habitats is examined. Following the MIREN sampling protocol, 20 transects composed of three plots along each river and main road, were established in each study region. Plant species cover and a range of site-specific factors were collected. In total, 641 plant species were recorded, of which 20 were alien. Alien species richness along roads was slightly higher compared to rivers, and the composition of the alien flora differed markedly between roads and rivers. Further, alien plant species richness decreases with distance to roads and rivers (indicating that adjacent habitats are less invaded), as well as with increasing elevation. Mowing along roadsides resulted in lower alien plant species cover, but higher alien plant species richness. Finally, compositional dissimilarity between sites showed that elevation, proximity of a plot to a river or road, and alien plant cover are important factors for higher dissimilarity. This study demonstrates that both natural (rivers) and man-made (roads) corridors play an essential role in the upward spread of different alien plants in mountains.