Influence Of Ground Cover Research Articles

Influence of ground cover and tunnels on production of Red Russian kale in urban gardes

Kale, Brassica oleracea L. var. acephala, is an important urban crop for human health and may potentially be grown year-round even in a temperate climate. We investigated black plastic and straw mulch compared to bare soil cover in low tunnels at 10 urban garden sites and in low tunnels within a high tunnel in the USA to ascertain the influence on yield and nutrients of Red Russian kale, soil temperature, air temperature, weed pressure, and aphid abundance. Kale had low yield in garden sites, likely because the outside environment was too cold for low tunnels to gain and retain heat. Cultivating kale in a high tunnel resulted in good yields, especially when paired with a low tunnel and plastic or straw mulch, which resulted in the highest air and soil temperatures. The amount of minerals in plants within the high tunnel largely did not vary across combinations of low tunnels and ground covers, except for copper and sulfur, which were lowest in plots with no low tunnel or ground cover. Also, dietary fiber was higher when no low tunnel or ground cover was used compared to plots with a low tunnel and no ground cover. Weeds were suppressed by straw and black plastic mulch, but none of the ground covers influenced aphid abundance. Overall, our work demonstrates that Red Russian kale can be grown in a temperate climate during winter with some combinations of tunnels and ground covers.

Which factors influence the density of birch (Betula pendula Roth) seeds in soil seed banks in temperate woodlands?

The natural regeneration of disturbed forest sites is becoming increasingly important due to climate change. Following disturbance events affecting large areas seed trees are often absent from the site, and regeneration solely by means of seed rain may not be successful. In these situations, soil seed banks are an important driver of the regeneration and reforestation of forest sites. The aim of the study was to determine the birch seed density in the soil of birch stands, spruce–birch stands and spruce stands dependent upon the number of seed trees (stands) and upon varying degrees of ground cover using the ‘seedling emergence method.’ The study revealed a significant link between the quantity of germinated birch seedlings in soil samples and the presence of seed sources. Seedling densities of birch in the different stand categories reached 2644–6414 seedlings per m2 [n m−2] in birch stands, 392–759 n m−2 in spruce–birch stands and 25–122 n m−2 in pure spruce stands. The density of germinated birch seedlings was also negatively affected by the soil layer. In all stand types, the factors humus thickness, litter cover, moss cover and herb cover had no significant influence on the amount of birch seedlings. Successful rapid regeneration of disturbed sites by means of the birch soil seed bank is guaranteed in cases where birch stands, or at least birch seed trees, were present before the event. The influence of ground cover on the regeneration potential of birch from the soil is negligible.

Influence of ground cover on earthworm communities in an unmanaged beech forest: linear gradient studies

Micro-scale changes in earthworm communities and ground cover types were studied along five transect lines in an unmanaged beech forest (Fontainebleau forest, France). Spatial patterns were interpreted in the light of interactions between earthworm species and forest architecture, ground vegetation and quantity as well as quality of litter. The anecic Lumbricus terrestris was associated with patches of the grass Melica uniflora, with poor litter cover, while most epigeic species were favoured by accumulation of litter in the absence of grass vegetation. The endogeic Aporrectodea caliginosa avoided, at least in summer time, 4-year-old gaps opened by wind storms. Under the shade of beeches, the evergreen spiny shrub Ruscus aculeatus, and in opened areas the giant herb, Phytolacca decandra, seemed repellent to most earthworm species.

Influence of ground cover on development of phytophthora crown and root rot of apple trees

The influence of ground cover with fall rye, perennial rye grass, oats, canola, quack grass, and timothy grass on percent mortality and disease severity ratings of phytophthora crown and root rot of apple trees was determined over five years under orchard conditions in the Okanagan Valley of British Columbia. Fall rye and perennial rye grass significantly (P = 0.05) reduced the disease compared with the hand-weeded control. There were no significant differences in the percent tree mortality among the timothy grass, quack grass, oats, canola, and the hand-weeded control treatments. These results indicate that use of fall rye or perennial rye grass as a ground cover will reduce the incidence of phytophthora crown and root rot of apple trees planted in sandy soils of nurseries or orchards where the disease is present and conditions are sufficiently wet.

Influence of ground cover on spider populations in a table grape vineyard

1. Cover crops and/or resident ground vegetation have been used in California vineyards to increase the number of predators and decrease the number of pestiferous herbivores. The most common resident predators in vineyards are spiders (Araneae). Several observational studies suggest that the addition of cover crops results in an increase in spider density and a decrease in insect pest densities.2. To test experimentally the effects of cover crops and/or resident ground vegetation (hereafter collectively referred to as ground cover) on spider populations, a 3‐year study was undertaken in a commercial vineyard. Large, replicated plots were established with and without ground cover during the growing season. Spider species diversity was analysed on the vines and on the ground cover.3. On the vines, there was no significant difference in spider species richness or the total number of spiders in plots with and without ground cover. There were differences in the relative abundance of two spiders between treatments, with one species (Trachelas pacificus [Chamberlin & Ivie]) more abundant in plots with ground cover and another (Hololena nedra Chamberlin & Ivie) more common on vines in plots with no ground cover. Annual variation in spider abundance was greater than variation due to ground cover treatment.4. On the ground cover, the spider species diversity was considerably different from that found on the vines above, suggesting that there is little movement of spiders between the ground cover and the vines. Enhancement of T. pacificus populations on vines with ground covers may be a result of prey species movement between the ground cover and the vines. Spider abundance was sparse on the bare ground.5. The maintenance of ground cover increased spider species diversity in the vineyard as a whole (vine and ground cover). However, the relatively small changes in spider abundance on the vines indicate there are limitations in the use of ground covers for pest management with respect to generalist predators.

Influence of Ground Cover on Beneficial Arthropods in Pecan

Arthropods were collected, identified, and counted on three dates to determine the effects of ground cover on arthropod type and density in pecan canopies. Ground covers were a grass sod (primarily bermudagrass,Cynodon dactylon[L.] Pers.), red clover (Trifolium pratenseL.), or a mixture of crimson clover (T. incarnatumL.) and hairy vetch (Vicia villosaRoth.). Arthropods collected represented eight orders of Insecta, three orders of Arachnida, and one Chilopoda. Ground cover had little effect on the density or type of arthropods present in the pecan canopy, except that densities ofChrysoperla rufilabris(Burmeister) were greater during July from pecans with a legume ground cover than from those with a grass ground cover.Chrysoperla rufilabrisis a major predator of aphids, which may suppress pecan aphid density. Other statistically significant differences in arthropod density between ground cover types were not of practical importance.

Influence of ground cover on dynamics of Amblyseius fallacis Garman (Acarina; Phytoseiidae) in New York apple orchards

Four studies were conducted between 1989 and 1992 to determine the influence of vegetation beneath apple trees on the dynamics of the mite predator Amblyseius fallacis (Garman). Withholding herbicide applications in the spring to allow ground cover to grow beneath trees did not result in greater numbers of A. fallacis in trees during the summer compared with plots where herbicides were applied and ground cover was greatly reduced. A survey of 23 commercial orchards revealed that A. fallacis overwintered on trees in many of these sites (14). Typhlodromus pyri (Scheuten) and Typhlodromus occidentalis (Nesbitt) were also found in the trees. In two of the orchards phytoseiids and European red mites, Panonychus ulmi (Koch), were sampled the following spring and summer. Amblyseius fallacis were found in the trees at bloom (10 May) and there was no evidence that they first increased in density in the ground cover and then colonized trees. Overwintering predator populations were repeatedly sampled in six orchards during autumn, winter, and spring 1991–1992. Amblyseius fallacis and T. pyri overwintered in high numbers in the trees. Amblyseius fallacis was also found in high numbers in the ground cover. Typhlodromus pyri also overwintered in the ground cover, but in lower numbers. Both predator species suffered high overwintering mortality, with that of T. pyri apparently less than that of A. fallacis. Treatment of ground vegetation with a pyrethroid insecticide in the spring did not affect arboreal A. fallacis densities during the summer; however, treatment of trees with the insecticide greatly reduced A. fallacis densities. In New York, ground cover in apple orchards directly beneath the trees does not appear to play a large role in the dynamics of A. fallacis.

Influence of ground cover and herbicide treatments onTetranychus urticae populations in peach orchards

Two-spotted spider mites,Tetranychus urticae Koch, were sampled in peach orchards to quantify abundance in trees over different types of ground cover to document the dispersal of mites from orchard-floor plants to trees. Mite populations developed more quickly and with higher densities in trees over ground cover compared to bare ground, and specifically over covers of predominantly narrowleaf vetch,Vicia angustifolia Reichard. Orchard floor plants such asVicia, Geranium, Lamium, andLepidium contained relatively high densities of mites during early spring, and may have formed the source for later peach-tree infestation.