Impact of management on foliage-dwelling arthropods and dynamics within permanent pastures

Abstract

The restoration of biodiversity within previously improved grasslands is an important objective worldwide. In some areas farmers receive remuneration for using specific strategies but the environmental responses to them are still uncertain. This study explored the short and long-term impacts of sheep grazing and/or hay cutting on arthropod foliage communities and flora within Welsh upland permanent pastures (UK). We measured arthropod abundance and diversity plus sward surface height, flower numbers and percentage of forbs and grasses. Data were collected during summer; twice before hay cutting and once shortly after. Total arthropod abundance was higher in grazed plots (due to Symphypleona flourishing) and family richness in hay cut plots, but taxa-specific responses occurred. Short-term effects reflected phenological changes (e.g. in Symphypleona or Cantharidae) and arthropod reductions after hay cut, when mostly Diptera remained. Arthropod communities were more abundant and diverse in flower-rich and forb-dominated plots managed by hay cutting and by hay cutting with aftermath grazing, although certain groups flourished in grazed only grass-dominated plots. The two managements based on a hay cut provided more heterogeneous environmental conditions than other management treatments, and these supported more diverse arthropod communities. The results make a valuable addition to the evidence base on which to base future land use policy at a time when trade-offs between agricultural production and nature conservation are under scrutiny across Europe.

Arthropod biodiversity associated to European sheep production systems

“…The percentage cover of grasses in this study correlated negatively with the percentage cover of forbs (R 2 = − 0.82, p < 0.001), the richness of pollinators (R 2 = − 0.42, p < 0.01) and the abundance of Orthoptera (R 2 = 0.39, p < 0.05). The inverse relationship in the percentage covers of grasses and forbs has been detected in previous studies (Rosa García and Fraser, 2019) and the negative relationship between the percentage cover of grasses and the abundance of pollinators could be related to the higher presence of wind-pollinated species and more reduced availability of pollen or nectar although grasses can include host plants to numerous groups (e.g. butterflies) and can provide nesting and overwintering sites.…”

“…The percentage cover of forbs was positively correlated to the sward height (R 2 = 0.31, p < 0.05) and the presence of higher number of flowers (R 2 = 0.38, p < 0.05). In upland permanent grasslands Rosa García and Fraser (2019) detected more abundant and diverse arthropod communities in flower-rich and forb-dominated plots managed by hay cutting and by hay cutting with aftermath sheep grazing, although certain groups were more abundant in grazed only and grass-dominated plots.…”

“…The Order Symphypleona showed higher abundances in SN than in MP (p < 0.05, Table 3). This order proliferates in humid environments and certain species can reach high numbers in grass dominated pastures where they can become a pest (Rosa García and Fraser, 2019).…”

“…The foliage arthropods were sampled with sweep nets as a rapid, inexpensive, and easily standardized protocol which has been successfully used to monitor their presence and responses to different management strategies, including sheep grazing (Rosa García and Miñarro, 2014;Rosa García and Fraser, 2019). The arthropods were sampled along six random linear transects (25 m long each one) per area and sweeps were performed in each transect.…”

“…The arthropod community contains excellent bioindicators to assess habitat quality and measure habitat differences (e.g., Niemelä et al, 1993;Longcore, 2003) due to their high sensitivity to environmental changes (Schowalter et al, 2003). The community composition is influenced by the characteristics of the habitat (including the vegetation structure and plant species composition in the sward) which in turn can be influenced by the grazing regime and/or the local conditions (Kleijn et al, 2001;Steffan-Dewenter et al, 2002, 2006Rosa García et al, 2013;Rosa García and Fraser, 2019). The EU sheep systems are highly diverse in management strategies, socioeconomic and environmental characteristics.…”