Photosynthetic Induction Dynamics to Sunflecks of Four Deciduous Forest Understory Herbs with Different Phenologies

2002 ◽  
Vol 163 (6) ◽  
pp. 913-924 ◽  
Author(s):  
James C. Hull

Botany ◽  
2021 ◽  
Author(s):  
Joseph A. Antos ◽  
Donald B. Zobel ◽  
Dylan Fischer

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.









AoB Plants ◽  
2017 ◽  
Vol 9 (5) ◽  
Author(s):  
Norman A Bourg ◽  
William J McShea ◽  
Valentine Herrmann ◽  
Chad M Stewart


1999 ◽  
Vol 29 (12) ◽  
pp. 1997-2002 ◽  
Author(s):  
Jeff P Castelli ◽  
Brenda B Casper ◽  
Jon J Sullivan ◽  
Roger Earl Latham

Early succession was followed in a 2.5-ha gap created by a severe wind storm in a 5.5-ha fragment of eastern North American deciduous forest. Understory vegetation cover by species, light, soil moisture, and levels of several major nutrients were measured in 1 × 2 m census plots 3 years prior to the disturbance. Coincidentally, the storm felled 50-55% of the trees over a portion of these plots. Vegetation cover by species was again measured in all plots 3 years following the disturbance. Species were grouped by growth form, and group cover values used to examine changes in the composition of the vegetation and to determine whether these changes were correlated with any measured predisturbance environmental variables. Given the size of the gap, shade-intolerant tree species were expected to increase but did not, most likely because of repression by the shrub layer. The main response to the disturbance appeared to occur through reorganization of existing vegetation. The value of predisturbance species cover data and limitations of our sample sizes are discussed.



2013 ◽  
Vol 6 (2) ◽  
pp. 219-230 ◽  
Author(s):  
Joshua A. Martinez ◽  
Mathew E. Dornbush

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.





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