Nitrogen addition in a freshwater marsh alters the quality of senesced leaves, promoting decay rates and changing nutrient dynamics during the standing-dead phase

2017 ◽  
Vol 417 (1-2) ◽  
pp. 511-521 ◽  
Author(s):  
Xinhou Zhang ◽  
Rong Mao ◽  
Changchun Song ◽  
Yanyu Song ◽  
Patrick M. Finnegan
Keyword(s):  
Nutrient Dynamics ◽  
Nitrogen Addition ◽  
Freshwater Marsh ◽  
Decay Rates ◽  
Standing Dead ◽  
Senesced Leaves

Input and decay of coarse woody debris in coniferous stands in western Oregon and Washington

1982 ◽  
Vol 12 (1) ◽  
pp. 18-28 ◽  
Author(s):  
Phillip Sollins
Keyword(s):  
Tree Mortality ◽  
Large Diameter ◽  
Mineral Soil ◽  
Small Diameter ◽  
Decay Rates ◽  
Root Turnover ◽  
Permanent Plots ◽  
Old Growth ◽  
Salvage Logging ◽  
Standing Dead

At 10 locations in Oregon and Washington, tree mortality resulted in dry-matter transfer of 1.5–4.5 Mg•ha−1•year−1 of boles and branches to the forest floor and 0.3–1.3 Mg•ha−1•year−1 of large-diameter roots directly to the mineral soil. The first value is about the same as that reported for leaf fall in similar stands; the second value generally is smaller than that reported for fine root turnover. Results are based on measurements by the U.S. Forest Service spanning 16–46 years and areas as large as 42 ha. Values based on intervals < 10 years were highly variable and potentially misleading.At an old-growth Douglas-fir stand in Washington, fallen boles accounted for 81 Mg/ha, standing dead for 54 Mg/ha. Density of fallen boles averaged from 0.14 to 0.27 g/cm3 depending on decay state. Values were lower than some previously reported because (1) our sample included small-diameter fallen boles that tend to decay rapidly, and (2) we measured density with techniques that minimized compaction and shrinkage.The decay rate at the old-growth stand, calculated indirectly by dividing bole mortality (megagrams per hectare per year) by the amount (megagrams per hectare) of fallen and standing dead woody material, was 0.028 year−1. This rate, three to five times those previously calculated directly from change in density alone, was almost identical to values calculated elsewhere from change in both volume and density. Decay rates based on change in density alone include only respired and leached material and exclude the large amount of material lost in fragmentation. This study shows the value of permanent plots, undisturbed by salvage logging, for retrospective studies of decomposition, nutrient cycling, and productivity.

scholarly journals Resistance to Botrytis cinerea and Quality Characteristics during Storage of Raspberry Genotypes

HortScience ◽  
2014 ◽  
Vol 49 (3) ◽  
pp. 311-319 ◽  
Author(s):  
Julia M. Harshman ◽  
Wayne M. Jurick ◽  
Kim S. Lewers ◽  
Shiow Y. Wang ◽  
Christopher S. Walsh
Keyword(s):  
Botrytis Cinerea ◽  
Weather Conditions ◽  
Decay Rates ◽  
Rubus Idaeus ◽  
Soluble Solids ◽  
Postharvest Quality ◽  
Red Raspberry ◽  
Ethylene Evolution ◽  
Weather Factors

Raspberries are a delicate, high-value crop with an extremely short shelf life exacerbated by postharvest decay caused by Botrytis cinerea Pers. European red raspberry (Rubus idaeus L.) is the most widely grown variety. Yellow (R. idaeus L.), black (R. occidentalis L.), and purple raspberries (R. ×neglectus Peck. or R. occidentalis ×idaeus hybrids) are available mainly at local markets and U-pick farms. To compare the postharvest quality of the raspberry color groups, pesticide-free fruit from cultivars and breeding selections of red, yellow, purple, and black raspberries were examined for oxygen radical absorbance capacity (ORAC), phenolics, anthocyanins, soluble solids, titratable acids, pH, color, firmness, decay and juice leakage rates, ethylene evolution, and respiration. There were significant correlations between decay rate and physiochemical properties. Both decay and leakage rates were correlated with weather conditions before harvest, but each color group responded differently to different weather factors. There were no correlations among changes in color, firmness, decay, or juice leakage rates. All the other color groups were less acidic than the familiar red raspberry. Yellow raspberries had the worst decay rates but the best leakage rates. Black and purple raspberries, with the highest phenolics and anthocyanins and the lowest ethylene evolution rates, resisted decay the longest but bled soonest.

Effect of nitrogen addition on soil organic carbon in freshwater marsh of Northeast China

2013 ◽  
Vol 70 (4) ◽  
pp. 1653-1659 ◽  
Author(s):  
Changchun Song ◽  
Deyan Liu ◽  
Yanyu Song ◽  
Rong Mao
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Northeast China ◽  
Nitrogen Addition ◽  
Freshwater Marsh

scholarly journals Seasonal nutrient dynamics and biomass quality of giant reed (Arundo donax L.) and miscanthus (Miscanthus x giganteus Greef et Deuter) as energy crops

2011 ◽  
Vol 6 (3) ◽  
pp. 24 ◽  
Author(s):  
Nicoletta Nassi o Di Nasso ◽  
Neri Roncucci ◽  
Federico Triana ◽  
Cristiano Tozzini ◽  
Enrico Bonari
Keyword(s):  
Nutrient Dynamics ◽  
Arundo Donax ◽  
Energy Crops ◽  
Giant Reed ◽  
Miscanthus X Giganteus ◽  
Biomass Quality ◽  
Arundo Donax L

Nitrogen content, decay rates, and decompositional dynamics of hollow versus solid hardwood logs in hardwood forests of Minnesota, U.S.A.

1998 ◽  
Vol 28 (9) ◽  
pp. 1276-1285 ◽  
Author(s):  
Cindy M Hale ◽  
John Pastor
Keyword(s):  
Residence Time ◽  
N Mineralization ◽  
Nutrient Dynamics ◽  
Hardwood Forests ◽  
Decay Rates ◽  
Net N Mineralization ◽  
Residence Times ◽  
Decay Class ◽  
Class 1 ◽  
Decay Parameters

Decay rates and nutrient dynamics of hardwood logs have been quantified in only a few studies over the last two decades. This study quantified and compared the nitrogen dynamics, residence times, and decay rates of hollow and solid maple and oak logs in decay classes 1 through 4. Decay parameters were not correlated with log age but did correlate with decay class. Hollow logs generally had lower percent original density and higher %N than did solid logs in each decay class. The point of maximum net immobilization of N and initial net N mineralization occurred late in decay class 1 or early in decay class 2. Residence time of logs in each decay class was low in decay class 1 (2 years), high in decay class 2 (17 years), and low in decay classes 3 and 4 (3 and 4 years, respectively). Decay rates varied by decay class, being low in decay classes 1 and 2 and high in decay classes 3 and 4.

scholarly journals Mental Mechanisms for Topics Identification

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Louis Massey
Keyword(s):  
Baseline Level ◽  
Short Term Memory ◽  
Decay Rates ◽  
Neural Systems ◽  
Long Term Memory ◽  
Neural Activation ◽  
Main Hypothesis ◽  
Term Memory

Topics identification (TI) is the process that consists in determining the main themes present in natural language documents. The current TI modeling paradigm aims at acquiring semantic information from statistic properties of large text datasets. We investigate the mental mechanisms responsible for the identification of topics in a single document given existing knowledge. Our main hypothesis is that topics are the result of accumulated neural activation of loosely organized information stored in long-term memory (LTM). We experimentally tested our hypothesis with a computational model that simulates LTM activation. The model assumes activation decay as an unavoidable phenomenon originating from the bioelectric nature of neural systems. Since decay should negatively affect the quality of topics, the model predicts the presence of short-term memory (STM) to keep the focus of attention on a few words, with the expected outcome of restoring quality to a baseline level. Our experiments measured topics quality of over 300 documents with various decay rates and STM capacity. Our results showed that accumulated activation of loosely organized information was an effective mental computational commodity to identify topics. It was furthermore confirmed that rapid decay is detrimental to topics quality but that limited capacity STM restores quality to a baseline level, even exceeding it slightly.

Decomposition and nutrient dynamics of ponderosa pine needles in a Mediterranean-type climate

1992 ◽  
Vol 22 (3) ◽  
pp. 306-314 ◽  
Author(s):  
Stephen C. Hart ◽  
Mary K. Firestone ◽  
Eldor A. Paul
Keyword(s):  
Sierra Nevada ◽  
Ponderosa Pine ◽  
Nutrient Dynamics ◽  
Decay Rates ◽  
Litter Fall ◽  
Decomposition Rates ◽  
Old Growth ◽  
Old Growth Forest ◽  
Significant Difference ◽  
Young Growth

A litter-bag technique was used to measure decay rates and assess changes in organic and inorganic constituents of ponderosa pine (Pinusponderosa Laws.) needle litter during decomposition over a 2-year period in old- and young-growth forests in the Sierra Nevada of California. Rates of mass loss were among the lowest reported for temperate and boreal forests, with annual decomposition constants of about 0.08 and 0.18 year−1 for the old- and young-growth forests, respectively. Apparently, the temporal separation of warm temperatures and moist conditions found in Mediterranean-type climates severely limits decomposition in these coniferous forests. In the old-growth forest, comparison of estimates of tree nutrient uptake with net releases of nutrients from fine litter during their 1st year of decomposition suggests that recent litter fall potentially acts as a significant source of P, Mg, and K for tree uptake in this forest; in contrast, recently fallen litter acts as a net sink for N, S, and Ca. Despite initially lower indices of litter quality for litter originating from the old–growth relative to the young–growth forest, no significant difference in decomposition rates of these two litter age-classes was found when placed at either site. This result does not support the hypothesis that decreases in decomposition rates during forest development are driven by decreases in the quality of litter fall.

scholarly journals In situ decomposition of northern hardwood tree boles: decay rates and nutrient dynamics in wood and bark

2014 ◽  
Vol 44 (12) ◽  
pp. 1515-1524 ◽  
Author(s):  
Chris E. Johnson ◽  
Thomas G. Siccama ◽  
Ellen G. Denny ◽  
Mary Margaret Koppers ◽  
Daniel J. Vogt
Keyword(s):  
Mass Loss ◽  
Sugar Maple ◽  
Nutrient Dynamics ◽  
Exponential Model ◽  
Fagus Grandifolia ◽  
Decay Rates ◽  
Nutrient Concentrations ◽  
Betula Alleghaniensis ◽  
Northern Hardwood ◽  
Clear Cutting

The decomposition of coarse woody debris contributes to forest nutrient sustainability and carbon (C) balances, yet few field studies have been undertaken to investigate these relationships in northern hardwood forests. We used a paired-sample approach to study the decomposition of sugar maple (Acer saccharum Marsh.), American beech (Fagus grandifolia Erhr.), and yellow birch (Betula alleghaniensis Britt.) boles at the Hubbard Brook Experimental Forest in New Hampshire. Mass loss over 16 years followed a first-order exponential decay pattern with half-lives ranging from 4.9 to 9.4 years in bark and from 7.3 to 10.9 years in wood. Nitrogen (N) and phosphorus (P) concentrations increased significantly during decomposition, resulting in sharp decreases in C:N and C:P ratios. We did not, however, observe significant net increases in the amount of N or P stored in decomposing boles, as reported in some other studies. Calcium (Ca) concentration decreased by up to 50% in bark but more than doubled in wood of all species. The retention of Ca in decomposing wood helps maintain Ca pools in this base-poor ecosystem. Together, the exponential model for mass loss and a combined power-exponential model for changes in nutrient concentrations were able to simulate nutrient dynamics in decomposing boles after clear-cutting in an adjacent watershed.

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