Microbial and Plant Community Structure Across a Primary Succession Gradient

Abstract

Microbial and plant community structure across a primary succession gradient.The formation of the organic layer within Scandinavian forest soil started about 10 000 yr ago, following the retreat of the continental ice sheet. Since then the land has been slowly rising in northern Europe and uplift still occurs on the coast of the Bothnian Bay at a rate of about 0.6 ± 0.9 m per 100 yr. Four, 300 m long, successional gradients were studied from the shoreline to a Scots pine (Pinus syl×estris) stand with a fully developed humus layer of a few centimetres' thickness. The plantless shoreline was followed by small foredunes and dunes, characterized by Agrostis stolonifera and Leymus arenarius, respectively, and the de¯ation basin characterized by lichens and sparse Festuca o×ina and Deschampsia¯exuosa. The study sites situated in Scots pine stands of about 25 and 40 yr age were characterized by sparse dwarf shrubs, lichens and bryophytes. The amount of organic matter in soil increased along the gradient. When the microbial biomass, estimated as indicative phospholipid fatty acids (PLFAs), was calculated on the organic matter basis, the total microbial biomass as well the amount of bacterial PLFAs decreased from the earlier stages of succession towards the pine forest. The ratio of fungal to bacterial PLFAs increased along the succession. The bacterial community structure in the shore soil was different to that in the dune soil or in forested zones. On the plantless shore the microbial community was almost completely described by PLFAs indicative of Gram-negative bacteria. In addition to these bacterial PLFAs, dunes were characterized by PLFAs indicative of actinomycetes. Thus, the fungal part of the microbial community seemed to respond most to the accumulation of organic matter and increasing C:N ratio, while the bacterial biomass and bacterial community structure seemed also to re¯ect the composition of the vegetation and the varying quality of the organic matter.

Root endophytes along a primary succession gradient in northern Finland

“…The lowest number of isolates per root system was obtained from the early successional dune ridge (0.5 per root system) and highest from the late successional site (1.5 per root system). Although the goal of this study was not to monitor the absolute number of strains between different successional stages and the number of samples varied between sites, our result is in line with the reports on increased fungal abundance along with increasing soil successional age (Pennanen et al 2001). The sequencing of the isolates revealed that most of the fungal strains were conspecific with the dark septate endophyte Phialocephala fortinii (27 strains out of 38).…”

“…The mineral soil in the seashore is sand with low total nitrogen content. Soil organic matter increases and soil pH decreases along the succession gradient towards late succession (Pennanen et al 2001). The plant material was collected in early growing season, (June 5th, 2007) from five sites representing four kinds of habitats: Site 1: A sandy seashore dune ridge area with only occasional patches of Empetrum nigrum L. (subspecies hermaphroditum, referred to as Empetrum nigrum hereafter) and the grasses Deschampsia flexuosa L. and Agrostis spp.…”

“…On sandy seashores, the first vascular plants typically are separately-growing non-mycorrhizal ruderals, for example, members of Chenopodiaceae, Polygonaceae and Brassicaceae (Read 1989;Smith and Read 1997). They soon become replaced by arbuscular mycorrhizal (AM) perennial graminoids that grow on the dunes (Read 1989;Pennanen et al 2001). Vegetation on the deflation basin beyond the dunes is comprised of patchily distributed ericoid mycorrhizal dwarf shrubs as well as sparse ECM (ectomycorrhizal) trees and few AM graminoid and forb species.…”

“…Furthermore, as the bacterial phospholipid fatty acids (PLFAs) decrease in the soil organic matter, the fungal PLFAs increase along the succession of sandy shores (Pennanen et al 2001).…”

Seasonal Variations in Soil and Bacteriological Properties as Affected by Phytogenic Mounds (Nebkhas) of Halocnemum strobilaceum in Lake Manzala, Egypt

“…Along with this variation in microbial community composition, microbial function, as measured through nutrient Society"pp.133 -145 (2017) turnover, changes may also occur on a seasonal basis (DeForest et al, 2009). Previous studies examining relationship between vegetation patchiness and microbial communities were conducted in a forest ecosystem (Pennanen et al, 2001) or volcanic desert ecosystem (Yoshitake et al, 2013). However, studies on examining the bacterial communities and activity associated with patchiness of halophytic vegetation in an extreme saline-alkali wet land are rare.…”