Flowering, growth and defence in the two sexes: consequences of herbivore exclusion for Salix polaris

2002 ◽  
Vol 16 (5) ◽  
pp. 649-656 ◽  
Author(s):  
Carsten F. Dormann ◽  
Christina Skarpe
Keyword(s):  
Salix Polaris ◽  
Herbivore Exclusion

scholarly journals Effects of Grazer Exclusion on Carbon Cycling in Created Freshwater Wetlands

Land ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 805
Author(s):  
Delanie M. Spangler ◽  
Anna Christina Tyler ◽  
Carmody K. McCalley
Keyword(s):  
Soil Carbon ◽  
Carbon Cycling ◽  
Belowground Biomass ◽  
Freshwater Wetlands ◽  
Wetland Creation ◽  
Free Access ◽  
Exclusion Experiment ◽  
Herbivore Exclusion ◽  
Sequestration Potential ◽  
Natural Wetlands

Wetland ecosystems play a significant role in the global carbon cycle, and yet are increasingly threatened by human development and climate change. The continued loss of intact freshwater wetlands heightens the need for effective wetland creation and restoration. However, wetland structure and function are controlled by interacting abiotic and biotic factors, complicating efforts to replace ecosystem services associated with natural wetlands and making ecologically-driven management imperative. Increasing waterfowl populations pose a threat to the development and persistence of created wetlands, largely through intensive grazing that can shift vegetation community structure or limit desired plant establishment. This study capitalized on a long-term herbivore exclusion experiment to evaluate how herbivore management impacts carbon cycling and storage in a created wetland in Western New York, USA. Vegetation, above- and belowground biomass, soil carbon, carbon gas fluxes and decomposition rates were evaluated in control plots with free access by large grazers and in plots where grazers had been excluded for four years. Waterfowl were the dominant herbivore at the site. Grazing reduced peak growing season aboveground biomass by over 55%, and during the summer, gross primary productivity doubled in grazer exclusion plots. The shift in plant productivity led to a 34% increase in soil carbon after exclusion of grazers for five growing seasons, but no change in belowground biomass. Our results suggest that grazers may inhibit the development of soil carbon pools during the first decade following wetland creation, reducing the carbon sequestration potential and precluding functional equivalence with natural wetlands.

Using photography to estimate above-ground biomass of small trees

2020 ◽  
pp. 1-7
Author(s):  
Brandon R. Hays ◽  
Corinna Riginos ◽  
Todd M. Palmer ◽  
Benard C. Gituku ◽  
Jacob R. Goheen
Keyword(s):  
Cost Effective ◽  
Allometric Equation ◽  
Biomass Estimation ◽  
Above Ground Biomass ◽  
Tree Biomass ◽  
East African ◽  
Ground Biomass ◽  
Herbivore Exclusion ◽  
Significant Difference ◽  
Allometric Relation

Abstract Quantifying tree biomass is an important research and management goal across many disciplines. For species that exhibit predictable relationships between structural metrics (e.g. diameter, height, crown breadth) and total weight, allometric calculations produce accurate estimates of above-ground biomass. However, such methods may be insufficient where inter-individual variation is large relative to individual biomass and is itself of interest (for example, variation due to herbivory). In an East African savanna bushland, we analysed photographs of small (<5 m) trees from perpendicular angles and fixed distances to estimate above-ground biomass. Pixel area of trees in photos and diameter were more strongly related to measured, above-ground biomass of destructively sampled trees than biomass estimated using a published allometric relation based on diameter alone (R2 = 0.86 versus R2 = 0.68). When tested on trees in herbivore-exclusion plots versus unfenced (open) plots, our predictive equation based on photos confirmed higher above-ground biomass in the exclusion plots than in unfenced (open) plots (P < 0.001), in contrast to no significant difference based on the allometric equation (P = 0.43). As such, our new technique based on photographs offers an accurate and cost-effective complement to existing methods for tree biomass estimation at small scales with potential application across a wide variety of settings.

scholarly journals Salix polaris leaves dated at 14.3 ka BP from northern Jylland

2003 ◽  
Vol 50 ◽  
pp. 151-155
Author(s):  
B. Korsager ◽  
O. Bennike ◽  
M. Houmark Nielsen
Keyword(s):  
Woody Plants ◽  
Last Deglaciation ◽  
Salix Polaris ◽  
Plant Remains ◽  
The Last Deglaciation

Leaves of the tiny willow Salix polaris Wahlenberg from a lake deposit in northern Jylland have been dated to c. 14,300 cal. years BP. These are some of the oldest dated plant remains after the last deglaciation from an on-shore deposit in Denmark. Salix polaris was probably one of the first woody plants that immigrated to Denmark, where it played an important role on the raw, carbonate rich but unstable soils.

Leaf photosynthetic characteristics and net primary production of the polar willow (Salix polaris) in a high arctic polar semi-desert, Ny-Ålesund, Svalbard

2002 ◽  
Vol 80 (11) ◽  
pp. 1193-1202 ◽  
Author(s):  
Hiroyuki Muraoka ◽  
Masaki Uchida ◽  
Masako Mishio ◽  
Takayuki Nakatsubo ◽  
Hiroshi Kanda ◽  
...  
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Natural Habitat ◽  
Leaf Age ◽  
High Arctic ◽  
Photosynthetic Characteristics ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Salix Polaris ◽  
Temperature Conditions

Photosynthetic characteristics and their leaf-age dependence were examined to estimate ecophysiological effects on net primary production (NPP) of a polar willow (Salix polaris), a dominant dwarf shrub species in a polar semi-desert area of Ny-Ålesund, Svalbard. Leaves of S. polaris emerged just after snowmelt in early July in 2000; flowers were initiated within 1 week, and fruits in late July. Light-saturated rate of photosynthesis and stomatal conductance to water vapor increased rapidly to their maximum values within 1 week after leaf emergence and then decreased gradually. Depending on the leaf age, photosynthetic rates saturated at photosynthetically active photon flux density (PPFD) of 200–400 µmol·m–2·s–1, which is the light level usually available in the natural habitat. Optimum leaf temperature of photosynthesis ranged from 10 to 18°C, while air temperature in the habitat ranged from 8 to 20°C. These light and temperature responses of photosynthesis of S. polaris would be suitable for efficient carbon gain in the natural habitat characterized by highly variable light and temperature conditions. Using the photosynthetic and respiratory characteristics, biomass distribution, and meteorological data, NPP of S. polaris in the current year was estimated to be 26.1 g C·m–2. A model simulation of rising temperature conditions predicted a reduction of NPP because of a large increase in respiration. It was suggested that temperature condition and leaf phenological aspects strongly influence the carbon fixation by plants in the high arctic area studied.Key words: arctic semi-desert, climate change, net ecosystem production (NEP), net primary production (NPP), Salix polaris, photosynthesis.

scholarly journals What explains tick proliferation following large-herbivore exclusion?

2018 ◽  
Vol 285 (1878) ◽  
pp. 20180612
Author(s):  
Georgia Titcomb ◽  
Robert M. Pringle ◽  
Todd M. Palmer ◽  
Hillary S. Young
Keyword(s):  
Large Herbivore ◽  
Herbivore Exclusion

scholarly journals Nutrients cause grassland biomass to outpace herbivory

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
E. T. Borer ◽  
W. S. Harpole ◽  
P. B. Adler ◽  
C. A. Arnillas ◽  
M. N. Bugalho ◽  
...  
Keyword(s):  
Human Activities ◽  
Food Resource ◽  
Grazing Intensity ◽  
Fire Risk ◽  
Nutrient Supply ◽  
Nutrient Inputs ◽  
High Vertebrate ◽  
Herbivore Exclusion ◽  
Live Biomass ◽  
Consumer Control

AbstractHuman activities are transforming grassland biomass via changing climate, elemental nutrients, and herbivory. Theory predicts that food-limited herbivores will consume any additional biomass stimulated by nutrient inputs (‘consumer-controlled’). Alternatively, nutrient supply is predicted to increase biomass where herbivores alter community composition or are limited by factors other than food (‘resource-controlled’). Using an experiment replicated in 58 grasslands spanning six continents, we show that nutrient addition and vertebrate herbivore exclusion each caused sustained increases in aboveground live biomass over a decade, but consumer control was weak. However, at sites with high vertebrate grazing intensity or domestic livestock, herbivores consumed the additional fertilization-induced biomass, supporting the consumer-controlled prediction. Herbivores most effectively reduced the additional live biomass at sites with low precipitation or high ambient soil nitrogen. Overall, these experimental results suggest that grassland biomass will outstrip wild herbivore control as human activities increase elemental nutrient supply, with widespread consequences for grazing and fire risk.

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