Grassland management for stem-boring insects: Abandoning small patches is better than reducing overall intensity

• Published in: Agriculture, ecosystems & environment Vol. 167; pp. 38 - 42
• Main Authors: Rothenwöhrer, Christoph, Scherber, Christoph, Tscharntke, Teja
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.03.2013; Elsevier
• Subjects: Abandoned; Abandonment; Agronomy. Soil science and plant productions; Biological and medical sciences; Conservation practice; Control; Dactylis glomerata; Endoherbivore; environmental factors; feeds; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; Germany; Grasses; Grasslands; growing season; hibernation; Insects; land use change; Land-use intensity index; larval development; Management; meadows; niches; pastures; Phytopathology. Animal pests. Plant and forest protection; plant tissues; Protozoa. Invertebrates; range management; Reduction; Set-aside gradient; shoots; Spatial niche differentiation; sward; Germany; Set-aside gradient; Spatial niche differentiation; Endoherbivore; Land-use intensity index; Conservation practice; Dactylis glomerata; Monocotyledones; Gradient; Borer; Ecology; Land use; Pest; Grassland management; Gramineae; Angiospermae; Spermatophyta; Fodder crop
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2013.01.005

► Stem-borer communities among habitats varying in disturbance frequency were compared. ► Reducing management over a 1-season period is not sufficient to enhance insect abundances. ► Species mostly responded positively to grassland abandonment of 2-seasons or more. ► Regular land-use management narrows species’ spatial niche width. ► Small grassy strips should be excluded from grazing or mowing for at least two growing seasons. Grasses are a dominant component of meadows and pastures, harboring an often overlooked diversity of non-pest stem-boring insects that feed and develop exclusively enclosed by plant tissue inside grass shoots. Surprisingly, the effects of land-use management on these highly specialized communities have rarely been studied. Here, the applicability of short-term management reduction as a conservational tool, increasing stem-borer colonization success, was examined. On 41 grasslands in Germany a temporal gradient of set-aside treatments was established by experimentally excluding subplots from management, or by a priori selection of already abandoned grassland patches. Stem-borer abundances and attack heights on resulting managed, 1-season unmanaged and ≥2-seasons abandoned treatments were compared. Grassland management had a negative effect on stem-borer colonization success and spatial niche differentiation. Reducing management over a 1-season period did not enhance abundances. Two out of three species responded positively only to an abandoning treatment lasting ≥2-seasons, which was also reflected by the decreasing spatial overlap in this treatment. Even though grass shoots in unmanaged areas were on average 14.9cm taller than in managed areas, stem-borer abundances did not differ between the latter treatments. Hence, preserving essential larval development and hibernation habitats in future rotational set-aside schemes requires a management exclusion period of at least two growing seasons. From these grassy strips, e.g. located at meadow edges, highly specialized stem-borers can re-colonize sward islets on surrounding intensively managed grasslands, despite of ever changing land-use practices and environmental conditions.