Changes of Scots Pine Phyllosphere and Soil Fungal Communities during Outbreaks of Defoliating Insects

Abstract

Abstract:Outbreaks of forest pests increase with climate change, and thereby may affect microbial communities and ecosystem functioning. We investigated the structure of phyllosphere and soil microbial communities during defoliation by the nun moth (Lymantria monacha L.) (80% defoliation) and the pine tree lappet (Dendrolimus pini L.) (50% defoliation) in Scots pine forests (Pinus sylvestris L.) in Germany. Ribosomal RNA genes of fungi and bacteria were amplified by polymerase chain reaction (PCR), separated by denaturing gradient gel electrophoresis (DGGE), and subsequently sequenced for taxonomic assignments. Defoliation by both pests changed the structure of the dominant fungal (but not bacterial) taxa of the phyllosphere and the soil. The highly abundant ectomycorrhizal fungal taxon (Russula sp.) in soils declined, which may be attributed to insufficient carbohydrate supply by the host trees and increased root mortality. In contrast, potentially pathogenic fungal taxa in the phyllosphere increased during pest outbreaks. Our results suggest that defoliation of pines by insect pest, change the structure of fungal communities, and thereby indirectly may be contributing to aggravation of tree health.

The Abundance of Fungi, Bacteria and Denitrification Genes during Insect Outbreaks in Scots Pine Forests

“…Reference [26]). Briefly, the DNA from 50 mg of finely ground soil, needle, feces, and litter was extracted following a CTAB protocol with two chloroform/isoamylalcohol steps with an intermediate phenol purification [27] and subsequent polyethylene glycol precipitation [28].…”

“…All the investigated forests were located in the federal state of Brandenburg, Germany. The detailed site and soil properties were described earlier [25,26]. The soil types at the study sites in both years were classified as podzols (Food and Agriculture Organization of the United Nations (FAO) classification) derived from glacial and aeolian medium sand deposits.…”

“…The standards were provided by D. Bru, French National Institute for Agricultural Research, Dijon, France. All target genes were cloned in plasmid pGEM-T (Promega, Mannheim, Germany) and multiplied in Escherichia coli JM109 grown in an LB medium [26] with ampicillin (50 µg/mL). For plasmid linearization, the restriction enzyme SalI was used.…”

Increased Forest Soil CO2 and N2O Emissions During Insect Infestation

“…Both sites did not differ significantly in their soil microbial community composition in early May prior the nun moth population peak [31]. Average annual temperature was 9.2 and 10.8 • C and average annual precipitation was 611 and 474 mm for the study sites in 2013 and 2014, respectively (German Federal Meteorological Service (DWD) and Climate Data Center (CDC), Weather Station Lindenberg (Station ID: 3015), 13.07.2018, see also Supplementary Figure S1; for a description of site properties, see [6,31]). We measured the CO 2 -C and N 2 O-N fluxes across one year (August 2013-July 2014), i.e., on three dates in 2013 (August-October with n = 18 for each date) and five dates in 2014 (March-July with n = 30 for each date).…”

Ectomycorrhizal Community on Norway Spruce Seedlings Following Bark Beetle Infestation

“…T. fibrillosa occupied twice as many seedlings in K2 than in REF, while C. geophilum showed an opposite trend. REF was characterized by the presence of Lactarius, Russula, and Cortinarius species, associated with healthy forests [20,36,37], with some were still found in K1. A similar trend was detected by Peter et al [33], who found T. fibrillosa increased its abundance on seedlings in a locality affected by air pollution with increasing damage intensity, while Russula and Lactarius species preferred sites with lower damage levels.…”