Physiological and morphological responses to shade and nutrient additions of Claytonia virginica (Portulacaceae): implications for the "vernal dam" hypothesis

1998 ◽  
Vol 76 (8) ◽  
pp. 1340-1349 ◽  
Author(s):  
Wendy B Anderson ◽  
William G Eickmeier
Keyword(s):  
Nutrient Cycling ◽  
Field Experiments ◽  
Deciduous Forest ◽  
Nutrient Addition ◽  
Bisphosphate Carboxylase ◽  
Spring Ephemerals ◽  
Nutrient Additions ◽  
Spring Ephemeral ◽  
Morphological Responses ◽  
Claytonia Virginica

Because of their unique phenology and physiology, spring ephemeral herbs are believed to play an important role in intrasystem nutrient cycling in deciduous forest ecosystems. It was hypothesized that they function as a "vernal dam" by temporarily sequestering nutrients and preventing leaching from the system during a period of high nutrient availability. However, spring ephemerals require high-irradiance growing conditions. How do their physiological and morphological responses to ambient light and shade limit their ability to sequester excess nutrients? We performed field experiments using Claytonia virginica L. as a model to test several responses to shade and increasing levels of nutrient additions. We also examined the biomass responses and nutrient storage capacities of other spring ephemeral herbs. In C. virginica, shading reduced ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco) activity, photosynthesis rate, specific leaf weight, leaf width/length (W/L), and biomass; nutrient additions increased W/L and biomass only under unshaded conditions. Other herbs responded similarly but reached maximum biomass at lower nutrient addition levels than C. virginica. Shading reduced and nutrient additions increased nitrogen and phosphorus concentrations in both C. virginica and other herbs. Shaded herbs generally reached nutrient saturation at lower nutrient addition levels than unshaded herbs. Overall, unshaded plants sequestered larger amounts of nutrients than shaded plants. This pattern is best explained by a reduction in biomass under shaded conditions. We concluded that C. virginica and other spring herbs, although important components in forest nutrient cycling in the early spring, are limited in their capacity to store excess nutrients, particularly when shaded.Key words: Claytonia virginica, nutrient cycling, spring ephemerals, vernal dam.

Nutrient resorption in Claytonia virginica L.: implications for deciduous forest nutrient cycling

2000 ◽  
Vol 78 (6) ◽  
pp. 832-839 ◽  
Author(s):  
Wendy B Anderson ◽  
William G Eickmeier
Keyword(s):  
Nutrient Cycling ◽  
Nutrient Availability ◽  
Deciduous Forests ◽  
P Availability ◽  
Resorption Efficiency ◽  
Spring Ephemerals ◽  
Nutrient Additions ◽  
Spring Ephemeral ◽  
Use Efficiency ◽  
Claytonia Virginica

According to the vernal dam hypothesis, spring ephemeral herbs temporarily sequester large nutrient pools in deciduous forests prior to canopy closure and return the nutrients to the soil following senescence of aboveground tissues. However, many species resorb nutrients from their leaves back to belowground tissues during senescence, and the degree of resorption is often associated with soil nutrient availability. Species that store large proportions of their absorbed nutrients between years are not participating in the temporary sequestering and rapid recycling of nutrients implied by the vernal dam. We investigated the extent to which Claytonia virginica L. sequestered and returned nutrients to the soil in response to nitrogen (N) and phosphorus (P) availability. We tested the effect of nutrient availability on nutrient use efficiency, resorption efficiency, and resorption proficiency (% nutrient in senescent leaves) of Claytonia. Nutrient additions significantly decreased N but not P use efficiency of Claytonia, particularly as the growing season progressed. Nutrient additions also significantly reduced N resorption efficiency from 80 to 47% and decreased P resorption efficiency from 86 to 56%. N and P resorption proficiencies were also significantly lower in senesced leaves of fertilized plants: N concentrations were 2.33% when unfertilized and 4.13% when fertilized, while P concentrations were 0.43% when unfertilized versus 0.57% when fertilized. When unfertilized, Claytonia was more efficient at resorption compared with other spring herbs, but similar to other species when fertilized. However, Claytonia was much less proficient in resorbing nutrients than other reported plants, because senescent tissues maintained substantially higher concentrations of N and P, particularly when fertilized. In conclusion, Claytonia, an important spring ephemeral species, exhibits physiological responses that emphasize its role in the vernal dam by its temporary sequestration and substantial, rapid return of nutrients in deciduous forests. Adding nutrients to the site increases the total mass and the relative proportion of nutrients that Claytonia returns to the soil rather than sequestering between seasons, which ultimately increases nutrient recycling rates within the entire system.Key words: Claytonia virginica, nutrient response, resorption efficiency, nutrient cycling, spring ephemerals, vernal dam.

Cooler temperatures favour growth of wild leek (Allium tricoccum), a deciduous forest spring ephemeral

Botany ◽  
2012 ◽  
Vol 90 (11) ◽  
pp. 1125-1132 ◽  
Author(s):  
Antoine Bernatchez ◽  
Line Lapointe
Keyword(s):  
Temperature Regime ◽  
Deciduous Forest ◽  
Plant Biomass ◽  
Photochemical Efficiency ◽  
Early Spring ◽  
Photochemical Quenching ◽  
Spring Ephemerals ◽  
Spring Ephemeral ◽  
Short Period ◽  
Allium Tricoccum

Allium tricoccum Aiton is a common spring ephemeral of hardwood deciduous forests of northeastern North America. It takes advantage of the short period of high light conditions between snowmelt and canopy closure to complete its vegetative life cycle and accumulate carbohydrate reserves for the following year. Previous studies on other spring ephemerals have shown that growth of these species is enhanced when grown at low temperature, typical of very early spring. We thus quantified the effect of three growth temperature regimes, i.e., 18 °C day – 14 °C night, 12 °C day – 8 °C night, and 8 °C day – 6 °C night, which have previously been tested on Erythronium americanum, another spring ephemeral. Gas exchange, chlorophyll a fluorescence, and plant biomass were measured repeatedly throughout the growth season. Growth was greatest under the 12 °C day – 8 °C night temperature regime, consistent with enhanced net photosynthetic rates (Pn), photochemical quenching (qP), and photochemical efficiency of photosynthesis (ΦPSII) at this temperature regime throughout the season. Pn was similar at 18 °C day – 14 °C night and 8 °C day – 6 °C night, but leaves had a greater duration at 8 °C day – 6 °C night; however, bulb biomass was not greater at 8 °C day – 6 °C night than at 18 °C day – 14 °C night. This study corroborates the general sensitivity of spring ephemerals to warmer temperatures. It also highlights species differences that might be caused by their specific carbon metabolism at the bulb level.

L'importance des interactions dans une population de l'araignée Lepthyphantes flavipes (Blackwall) (Araneida: Linyphiidae)

1991 ◽  
Vol 69 (8) ◽  
pp. 2246-2249 ◽  
Author(s):  
Jacques Leclerc ◽  
Patrick Blandin
Keyword(s):  
Field Experiment ◽  
Web Sites ◽  
Web Site ◽  
Field Experiments ◽  
Deciduous Forest ◽  
Interference Competition ◽  
Forest Litter

The significance of interactions between spiders was evaluated in a population of Lepthyphantes flavipes (Blackwall) that occurs on a deciduous forest litter. Three hypotheses are presented: (i) H0, interactions, mainly interference competition for web sites, are not important in structuring the population; (ii) H1, spiders tend to use silk from deserted webs; (iii) H2, dominant spiders tend to displace resident subordinate spiders from their web sites. Because spinning a new web is costly in Lepthyphantes, substantial gain may be obtained when moving to a new web site under hypotheses H1, and H2. These hypotheses were tested in a field experiment by means of plastic rings introduced on litter as web sites. Results confirm hypothesis H0. Hypothesis H1 is not rejected for small-sized spiders and needs to be explored through more field experiments. Hypothesis H2 is rejected.

scholarly journals Late canopy closure delays senescence and promotes growth of the spring ephemeral wild leek (Allium tricoccum)

Botany ◽  
2017 ◽  
Vol 95 (5) ◽  
pp. 457-467 ◽  
Author(s):  
Pierre-Paul Dion ◽  
Julie Bussières ◽  
Line Lapointe
Keyword(s):  
Light Availability ◽  
Growing Season ◽  
Tree Canopy ◽  
Strong Impact ◽  
Bud Burst ◽  
Growth And Survival ◽  
Spring Ephemerals ◽  
Spring Ephemeral ◽  
Tree Leaf ◽  
Allium Tricoccum

Spring ephemerals take advantage of the high light conditions in spring to accumulate carbon reserves through photosynthesis before tree leaves unfold. Recent work has reported delayed leaf senescence under constant light availability in some spring ephemerals, such as wild leek (Allium tricoccum). This paper aims to establish whether tree canopy composition and phenology can influence the growth of spring ephemerals through changes in their phenology. Wild leek bulbs were planted in 31 plots in southern Quebec, Canada, under canopies varying in composition and densities. Light availability and tree phenology were measured, along with other environmental conditions, and their effect on the growth of wild leeks was assessed with a redundancy analysis. Higher light availability resulted in better growth of wild leeks. The plants postponed their senescence under trees with late bud-burst, and thus better bulb growth and seed production were achieved. The tree litter and temperature and moisture levels of the soil also influenced the growth and survival of wild leeks. Thus, tree leaf phenology appears to have a strong impact on the growth of spring ephemerals by modulating the length of their growing season and their photosynthetic capacity. This underlines the importance of considering the variation of light availability throughout the growing season in the study of spring ephemerals.

scholarly journals Ecosystem Entanglement and the Propagation of Nutrient-Driven Instability

2020 ◽  
Author(s):  
Kevin S. McCann ◽  
A.S MacDougall ◽  
G.F. Fussmann ◽  
C. Bieg ◽  
K. Cazelles ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Nutrient Loading ◽  
Transport Theory ◽  
Nutrient Addition ◽  
Edible Plant ◽  
Nutrient Additions ◽  
Theoretical Synthesis ◽  
Human Modification ◽  
And Function

ABSTRACTAlmost 50 years ago, Michael Rosenzweig pointed out that nutrient addition can destabilize food webs, leading to loss of species and reduced ecosystem function through the paradox of enrichment. Around the same time, David Tilman demonstrated that increased nutrient loading would also be expected to cause competitive exclusion leading to deleterious changes in food web diversity. While both concepts have greatly illuminated general diversity-stability theory, we currently lack a coherent framework to predict how nutrients influence food web stability across a landscape. This is a vitally important gap in our understanding, given mounting evidence of serious ecological disruption arising from anthropogenic displacement of resources and organisms. Here, we combine contemporary theory on food webs and meta-ecosystems to show that nutrient additions are indeed expected to drive loss in stability and function in human-impacted regions. However, this loss in stability occurs not just from wild oscillations in population abundance, but more frequently from the complete loss of an equilibrium due to edible plant species being competitively excluded. In highly modified landscapes, spatial nutrient transport theory suggests that such instabilities can be amplified over vast distances from the sites of nutrient addition. Consistent with this theoretical synthesis, the empirical frequency of these distant propagating ecosystem imbalances appears to be growing. This synthesis of theory and empirical data suggests that human modification of the Earth’s ecological connectivity is “entangling” once distantly separated ecosystems, causing rapid, expansive, and costly nutrient-driven instabilities over vast areas of the planet. The corollary to this spatial nutrient theory, though -- akin to weak interaction theory from food web networks -- is that slow spatial nutrient pathways can be potent stabilizers by moderating flows across a landscape.

Nutrient Cycling in a Stand of Acacia holosericea A. Cunn. Ex G. Don. III. Calcium, Magnesium, Sodium and Potassium.

1983 ◽  
Vol 31 (2) ◽  
pp. 141 ◽  
Author(s):  
. NP.J ◽  
MJ Dalling
Keyword(s):  
Nutrient Cycling ◽  
Nutrient Addition ◽  
The Other ◽  
Total Rainfall ◽  
Other Hand ◽  
Acacia Holosericea ◽  
Calcium Magnesium ◽  
Sodium And Potassium ◽  
Leaching Surface

Nutrient cycling by a 3-year-old Acacia holosericea plantation (1111 trees ha-1) was studied over a 13-month period. The gross accumulation of each nutrient in the various above-ground organs was calculated from the net increase over the study period plus the amounts lost by leaching and litterfall. Gross accumulation was greatest for calcium (22.4 kg ha-1), and potassium (18.8 kg ha-1), sodium (6.8 kg ha-1), followed by magnesium (5.2 kg ha-1). Biochemical recycling was greatest for calcium (10%) magnesium (8%), sodium (3%) and potassium (2%); however, this may be an overestimate as some of the apparent mobilization was undoubtedly due to leaching. Litter return accounted for 14% of the gross accumulation for potassium, 11% of magnesium, 10% of sodium and 9% of calcium. Litterfall accounted for 90% of the return of calcium to the soil and 75% of the return of magnesium. On the other hand, transfer in solution (leaching, surface wash) accounted for 88% of the return of sodium from the canopy to the soil and 59% of the return of potassium. Over the period 1 January 1979 to 28 February 1980 (total rainfall 2261 mm), the addition of nutrients in area precipitation was greatest for sodium (23.6 kg ha-1), followed by potassium (11.2 kg ha-1), calcium (6.8 kg ha-1) and magnesium (1.8 kg ha-1). Throughfall and stemflow increased the concentration of nutrients, such that the total nutrient addition to the soil was greatest for sodium (28.8 kg ha-1) followed by potassium (15.0 kg ha-1), calcium (7.0 kg ha-1) and magnesium (2.0 kg ha-1). These additions to the soil are significant in relation to the gross accumulation of these elements by Acacia holosericea.

Methane uptake by various forest soils with and without litter

2020 ◽  
Author(s):  
Anna Walkiewicz ◽  
Piotr Bulak ◽  
Bruce Osborne ◽  
Mohammad Ibrahim Khalil ◽  
Syed Faiz-ul Islam ◽  
...  
Keyword(s):  
Forest Soils ◽  
Field Experiments ◽  
Deciduous Forest ◽  
Coniferous Forest ◽  
Mixed Forest ◽  
Ghg Emissions ◽  
Atmospheric Methane ◽  
Litter Layer ◽  
Negative Effect ◽  
Dry Conditions

<p>Forest soils are often a sink for atmospheric methane (CH<sub>4</sub>) and are thus worth special attention in the context of mitigation of greenhouse gases (GHGs) and offset of agricultural GHG emissions at farm to national levels. The litter layer influences the exchange of GHGs between soil and atmosphere; however, most studies focus on the contribution of only soil to the CH<sub>4</sub> cycle. In order to improve the inventory of this gas, it is worth investigating how litter influences the exchange of GHGs. Its effect on CH<sub>4</sub> uptake may vary in deciduous and coniferous sites due to the different properties of litter. Field experiments were carried out to assess the CH<sub>4</sub> uptake capability in 5 different soil types (with and without litter) under different forest types (deciduous, coniferous, and mixed) in Poland. During summer 2019, the highest CH<sub>4</sub> uptake (about 2 mg C m<sup>-2</sup> day<sup>-1</sup>) in a variant without litter on the ground was detected in Dystric Cambisol (with the highest C/N ratio) under a 100-year-old coniferous forest and in Albic Luvisol under a 58-year-old mixed forest. The presence of the litter level reduced the CH<sub>4</sub> flux in the range of 6-27% in these locations. Methane consumption was the lowest in silty soils (~ 0.4 – 1 mg C m<sup>-2</sup> day<sup>-1</sup>) in the mixed forest and decreased by 13-29% when covered with the litter layer. The negative effect of the litter layer on CH<sub>4</sub> absorption was the lowest (~ 3-4%) in sandy Eutric Gleysol under a 75-year-old deciduous forest with 90% of oak and 10% of European hornbeam. The dry conditions in the summer 2019 (with total rainfall 163 mm during the tested months in the studied region) resulted in low moisture in both the litter and soil. However, even low-humidity litter (below 10%) reduced CH<sub>4</sub> consumption rates in the measured sites.</p><p>Research was partially conducted under the project financed by Polish National Centre for Research and Development within of ERA-NET CO-FUND ERA-GAS Programme (ERA-GAS/I/GHG-MANAGE/01/2018).</p>

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