c8.9.4 – Climate and site properties strongly affect microflora and mesofauna in subalpine forest soils

Pietramellara G (1), Sartori G (2), Graefe U (3), Thornton B (4), Ceccherini MT (1), Egli M (5), Ascher J* (1)

(1) Department of Plant, Soil and Environmental Science, University of Florence, Piazzale delle Cascine 18, 50144 Firenze, Italy; (2) Museo Tridentino di Scienze Naturali, Via Calepina 14, 38100 Trento, Italy; (3) IFAB Institut für Angewandte Bodenbiologie GmbH, Sodenkamp 62, 22337 Hamburg, Germany; (4) The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK; (5) Department of Geography, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
Collocazione: c8.9.4 – Tipo Comunicazione: Presentazione orale
8° Congresso SISEF *
Sessione 9: “Ecologia del Suolo, Micorrize e Biorimedio” *

Contatto: Giacomo Pietramellara (giacomo.pietramellara@unifi.it)

Abstract: This study focuses on the diversity and vertical distribution of microflora (bacteria, actinomycetes, fungi) and mesofauna (microannelids) in forested Alpine soils (Italian Alps) as a function of climate and site properties. A multidisciplinary approach, consisting of biochemical fingerprinting of soil microbial communities by nucleic acid based denaturing gradient gel electrophoresis (DGGE; qualitative), phospholipid fatty acid – fatty acid methyl ester analysis (PLFA-FAME; quantitative) and systematic investigation of the vertical distribution of microannelid communities was performed to assess and correlate soil biological and physico-chemical parameters of soil profiles differing in altitude (and consequently mean annual temperature) and exposure (south, north). Although the mesofauna and microflora showed a very complex behaviour, effects of climate and exposure could be clearly detected. Higher amounts of both Gram-positive and Gram-negative bacteria in the topsoil were measured at north-facing sites compared to the southern facing slopes. The higher proportion of Gram-negative bacteria at north-facing sites and higher altitudes (cooler climate) could be ascribed to their better adaptation to a lower temperature, pH and nutrient contents. A higher amount of total PLFA was, furthermore, measured at the north-facing sites and at higher altitudes (and therefore a cooler climate). Based on principal component analyses, distinct differences were discernible for the bacterial and the actinomycete patterns. These patterns quite nicely traced the expected thermal sequence. The δ13C signatures of the PLFA markers showed that the decomposition rate seemed to be lower at the cooler sites which gave rise to a lower respiratory loss and an accumulation of weakly decomposed organic material. In addition, the microannelid species assemblages clearly demonstrated that north-facing soils and cooler sites have a more acidic environment than south-facing soils. The highest species number of microannelids was found at south-facing sites. Generally, indicators of slight acidity were associated with the humus forms (ERB- and German classification) Hemimoder (F-Mull) and Dysmoder (Amphi). In contrast, the cooler and more acidic sites had Humimor (Mormoder) -like humus forms showing the absence of mixing activity of earthworms. Consequently, the humus form proved to be a good indicator of the soil biota (macro- and micro-biology). To our knowledge this is the first attempt that links solar radiation (exposure) and climate with soil biological factors using a multidisciplinary approach to characterise subalpine forest soils. Our results evidence the complex interactions of biotic and abiotic factors (above-and below-ground). Some first basic data are provided that will be helpful in assessing ecosystem changes under global change.

Parole chiave: Molecular Fingerprinting, Soil Micorflora And Mesofauna, Soil Climate, Soil Exposure

Citazione: Pietramellara G , Sartori G , Graefe U , Thornton B , Ceccherini MT , Egli M , Ascher J (2011). Climate and site properties strongly affect microflora and mesofauna in subalpine forest soils . 8° Congresso Nazionale SISEF, Rende (CS), 04 – 07 Ott 2011, Contributo no. #c8.9.4