Evaluating Buffer Strips along Boreal Streams Using Bryophytes as Indicators

Abstract

Abstract. Buffer strips have recently become the main management practice for reducing logging impact on stream habitats in boreal and temperate regions. The habitat value of buffer strips, however, has not received much attention, although riparian forests belong to the systems with the highest biodiversity in these regions. We used plants as indicators of the ability of buffer strips to maintain an environment similar to intact riparian forests in a boreal forest landscape in northern Sweden. We measured the growth of three common bryophyte species (Hylocomiastrum umbratum, Calypogeia integristipula, and Tritomaria quinquedentata) transplanted to riparian habitat close to a stream in clear-cut logged sites, 10-15 m wide buffer strips on each side of the stream, and intact (reference) sites. Each of the three site categories included six wet and six moist-mesic sites and the experiment was followed over three months in 1999.The species remained vital in the reference sites and grew substantially during the 3-mo-long experiment, but in the logged sites almost no growth was registered, and many shoots died (except for T. quinquedentata). The pattern was consistent irrespective of the ground moisture class. The performance of bryophytes in the moist-mesic buffer strips was almost as bad as in the logged sites, whereas in the wet buffer strips it was either intermediate between that in logged and reference sites (H. umbratum) or very similar to that in reference sites (C. integristipula and T. quinquedentata). The edge effect has previously been shown to vary depending on edge orientation, edge physiognomy, and weather conditions. We found that ground moisture can be of major importance as well. Although many buffer strips function better than no strips, 20-30 m wide strips (with a stream in the middle) through a logged area consist entirely of edge habitat. Increasing the buffer width and avoiding clear-cut logging on both sides of a watercourse would be the first steps to take for improving biodiversity conservation in riparian habitats. Our results also show that bryophytes are good indicators of habitat quality and efficient tools for assessing the ecological function of buffer strips.

Assessing the quality and usefulness of different taxonomic groups inventories in a semiarid Mediterranean region

“…It could be due to the special nature of these groups, which includes a high number of species and rare species having many of them narrow ecological niches (Hylander et al 2002;Millán et al 2006;Stewart and Mallik 2006;Picazo et al in press). So, the degree of inventory completeness depends on both the sampling effort carried out and the intrinsic nature of the species-abundance distribution: at the same sampling effort applied in a given geographic scale, the groups that hold a greater richness and higher number of rare species will show lower completeness values.…”

Interaction of edge influence from multiple edges: examples from narrow corridors

“…Narrow forest strips are often left between harvested areas to provide dispersal or movement corridors for wildlife (Debinski and Holt 2000), to serve as a seed source or because of restrictions on the size of harvested areas. Forested buffers around water bodies are maintained following timber harvest or agricultural development to protect aquatic ecosystems (Lowrance et al 1984;Peterjohn and Correll 1984;Gregory et al 1991;O'Laughlin and Belt 1995) and riparian habitat (Pearson and Manuwal 2001;Hylander et al 2002), and they may also provide wildlife habitat and help to maintain connectivity across the landscape (Castelle et al 1994;Brosofske et al 1997;Hannon et al 2002). Lakeshore buffers are influenced by a natural lakeshore edge and a cut edge, whereas riparian buffers along small streams are influenced by cut edges on two sides.…”

The importance of large-tree retention for the persistence of old-growth epiphytic bryophyte Neckera pennata in selection harvest systems

“…Reduced crown cover implies increased light intensity and most likely a warmer and drier microclimate. Forest bryophytes are generally sensitive to high light intensities, high temperatures, and severe desiccation (Proctor, 1990;Marschall and Proctor, 2004;Dynesius et al, 2008) and bryophyte growth and vitality may be reduced if microclimatic conditions are suddenly altered (Hylander et al, 2002;Dynesius et al, 2008). In fact, Wiklund and Rydin (2004) found that N. pennata displayed decreased growth and colonization near forest edges, the latter owing to lower germination success and viability of spores.…”