Belowground morphology and population dynamics of two forest understory herbs of contrasting growth form

Botany ◽  
2021 ◽  
Author(s):  
Joseph A. Antos ◽  
Donald B. Zobel ◽  
Dylan Fischer
Keyword(s):  
Pacific Northwest ◽  
Large Range ◽  
Forest Understory ◽  
Old Growth Forest ◽  
Forest Herbs ◽  
Understory Herbs ◽  
Small Roots ◽  
Chimaphila Umbellata ◽  
Range Of Variation ◽  
Xerophyllum Tenax

Forest understory herbs exhibit a large range of variation in morphology and life history. Here we expand the reported range of variation by describing the belowground structures of two very different species, Xerophyllum tenax and Chimaphila umbellata. We excavated individuals in forests of the Cascade Mountains, Pacific Northwest, USA. Xerophyllum tenax has short rhizomes, but an extensive root system that is exceptionally large among forest understory species. The roots reach 4 m in length and may occupy an area 50 times that of the aboveground canopy. In contrast, Chimaphila umbellata has very small roots, but an extensive rhizome system. The largest plant we excavated had 57 m of connected rhizomes and still had a seedling source. Both species have long-lived individuals but differ in response to disturbance. Based on monitoring of 151 permanent 1 m2 plots in an old-growth forest, X. tenax increased only minimally in density over 40 years following tephra deposition from the 1980 eruption of Mount St. Helens, whereas density of C. umbellata increased substantially. The very different morphology of these two species highlights the large range of variation found among forest herbs, which needs to be considered when examining the forest understory.

scholarly journals Secondary disturbance following a deposit of volcanic tephra: A 30 year record from old-growth forest understory

2021 ◽  
Author(s):  
Donald B Zobel ◽  
Joseph A. Antos ◽  
Dylan Grey Fischer
Keyword(s):  
Vegetation Change ◽  
Forest Disturbance ◽  
Canopy Cover ◽  
Soil Disturbance ◽  
Tree Canopy ◽  
Forest Understory ◽  
Old Growth ◽  
Old Growth Forest ◽  
Volcanic Ejecta ◽  
Woody Litter

Forest disturbance is usually described by effects on trees, and small disturbances to forest understory are seldom studied. Nevertheless, effective analyses of succession need to consider both stand-replacing and subsequent “secondary” disturbances in both canopy and understory. We estimated characteristics of 13 types of secondary disturbance in old-growth forest understory, and of canopy cover, after the 1980 tephra (aerially transported volcanic ejecta) deposition from Mount St. Helens, Washington. We sampled 100 1-m2 plots at each of four sites for vegetation change and types of disturbance at ten times from 1980-2010; we sampled tree canopy above each plot in 1980 and 2016. The number of canopy gaps increased 23 % and mean gap dimension 68 % during 36 years, mostly from loss of Abies amabilis. Secondary disturbance in understory affected 1.4 % of stand area per year. The areas affected by soil disturbance and effects of woody litter were similar. Erosion, greater in deep than in shallow tephra, peaked in 1981, whereas most litter-caused disturbances increased after 2000. Less frequent litter-based disturbances covered greater area. Our results differ from conclusions about non-volcanic understory disturbances. Secondary disturbances are variable, need more study, and are likely to affect many other systems.

scholarly journals Carbon Storage in Coarse and Fine Fractions of Pacific Northwest Old-Growth Forest Soils

2004 ◽  
Vol 68 (6) ◽  
pp. 2023-2030 ◽  
Author(s):  
P. S. Homann ◽  
S. M. Remillard ◽  
M. E. Harmon ◽  
B. T. Bormann
Keyword(s):  
Pacific Northwest ◽  
Carbon Storage ◽  
Forest Soils ◽  
Old Growth ◽  
Old Growth Forest

Effects of species mixtures on growth and stand development of Douglas-fir and red alder

2006 ◽  
Vol 36 (3) ◽  
pp. 768-782 ◽  
Author(s):  
Steven R Radosevich ◽  
David E Hibbs ◽  
Claudio M Ghersa
Keyword(s):  
Pacific Northwest ◽  
Tree Mortality ◽  
Stand Structure ◽  
Stand Density ◽  
Douglas Fir ◽  
Forest Understory ◽  
Red Alder ◽  
Structure Tree ◽  
Species Proportions ◽  
Species Mixtures

In the Pacific Northwest, a mixture of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnus rubra Bong.) often results when red alder regenerates naturally in planted conifer stands. The relationships among stand structure, tree mortality, tree size, and understory development in the two species mixtures were explored at two sites for the first 16 years after planting. Treatments included a range of species proportions, and red alder was either planted simultaneously with Douglas-fir or planting was delayed for 5 years. Red alder was also removed from some simultaneously planted proportions. Both replacement effects (total stand density held constant) and additive effects (stand density doubled) of the interaction were considered. Red alder grew relatively better at Cascade Head Experimental Forest in the Coast Range, while Douglas-fir grew better at H.J. Andrews Experimental Forest in the less temperate Cascade Mountains. Possible production benefits from mixed plantings were examined using two methods of calculation. Potential production benefits from certain planted proportions of the two species occurred at H.J. Andrews Experimental Forest. No planting time or species proportion resulted in yield improvements over monoculture stands at Cascade Head Experimental Forest. Understory species also varied because of differences in site and stand characteristics that resulted from the differences in planting times and species proportions.

Use of a Native Matrix Species to Facilitate Understory Restoration in an Overbrowsed, Invaded Woodland

2013 ◽  
Vol 6 (2) ◽  
pp. 219-230 ◽  
Author(s):  
Joshua A. Martinez ◽  
Mathew E. Dornbush
Keyword(s):  
Open Access ◽  
Native Species ◽  
Alliaria Petiolata ◽  
Interactive Effects ◽  
Forest Understory ◽  
Planting Density ◽  
Management Technique ◽  
Garlic Mustard ◽  
Restoration Technique ◽  
Understory Herbs

AbstractThe interactive effects of herbivory, exotic species, and other human-mediated changes to the biosphere are reducing species diversity and altering ecosystem services globally. In this study, we tested whether facilitation could be used as a management technique to restore a degraded northeast Wisconsin forest understory facing high white-tailed deer (Odocoileus virginianus) browse pressure and high abundance of the exotic herb garlic mustard [Alliaria petiolata (Bieb.) Cavara & Grande]. Specifically, we attempted to facilitate native understory restoration by planting or seeding native herbs into three different matrix densities of the native, browse-tolerant grass Virginia wildrye (Elymus virginicus L.), which were either protected from (fenced), or accessible to, deer browsing. Deer had minimal impacts on E. virginicus but significantly reduced the cover, survival, and flower production of white snakeroot [Ageratina altissima (L.) King & H.E. Robins.] transplants, largely independent of the density of E. virginicus plantings in open-access plots. In contrast, the richness and abundance of native-seeded species were not affected by deer access but were reduced by increasing E. virginicus densities. Alliaria petiolata cover was significantly higher in plots accessible to deer but declined significantly with increasing E. virginicus planting density in both open-access and fenced plots. These results were largely corroborated by results from an associated observational study, with the exception that natural E. virginicus stands supported slightly higher native-species richness than did adjacent areas lacking E. virginicus. Thus, although we found little support that establishing E. virginicus facilitated browse-susceptible native understory herbs during our short-term experimental study, restored E. virginicus successfully established, thereby increasing native species cover and significantly reducing the cover of the exotic A. petiolata. We suggest the planting of browse-tolerant native species, such as E. virginicus, as a viable restoration technique in heavily browsed, A. petiolata–invaded woodlands.

scholarly journals Biofilm Formation of Clinical Klebsiella pneumoniae Strains Isolated from Tracheostomy Tubes and Their Association with Antimicrobial Resistance, Virulence and Genetic Diversity

Pathogens ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1345
Author(s):  
Dorota Ochońska ◽  
Łukasz Ścibik ◽  
Monika Brzychczy-Włoch
Keyword(s):  
Genetic Diversity ◽  
Bacterial Adhesion ◽  
Biofilm Formation ◽  
Large Range ◽  
Bacterial Colonization ◽  
Genes Encoding ◽  
Invasive Infections ◽  
Tracheostomy Tubes ◽  
Range Of Variation

(1) Background: Due to the commonness of tracheotomy procedures and the wide use of biomaterials in the form of tracheostomy tubes (TTs), the problem of biomaterial-associated infections (BAIs) is growing. Bacterial colonization of TTs results in the development of biofilms on the surface of biomaterials, which may contribute to the development of invasive infections in tracheostomized patients. (2) Methods: Clinical strains of K. pneumoniae, isolated from TTs, were characterized according to their ability to form biofilms, as well as their resistance to antibiotics, whether they harbored ESβL genes, the presence of selected virulence factors and genetic diversity. (3) Results: From 53 patients, K. pneumoniae were detected in 18 of the TTs examined, which constitued 34% of all analyzed biomaterials. Three of the strains (11%) were ESβL producers and all had genes encoding CTX-M-1, SHV and TEM enzymes. 44.4% of isolates were biofilm formers, SEM demonstrating that K. pneumoniae formed differential biofilms on the surface of polyethylene (PE) and polyvinyl chloride (PVC) TTs in vitro. A large range of variation in the share of fimbrial genes was observed. PFGE revealed sixteen genetically distinct profiles. (4) Conclusions: Proven susceptibility of TT biomaterials to colonization by K. pneumoniae means that the attention of research groups should be focused on achieving a better understanding of the bacterial pathogens that form biofilms on the surfaces of TTs. In addition, research efforts should be directed at the development of new biomaterials or the modification of existing materials, in order to prevent bacterial adhesion to their surfaces.

Sign in / Sign up

Export Citation Format

Share Document