Extracting ecological and biophysical information from AVHRR optical data: An integrated algorithm based on inverse modeling

Satellite remote sensing provides the only means of directly observing the entire surface of the Earth at regular spatial and temporal intervals

Extracting ecological and biophysical information from AVHRR optical data: An integrated algorithm based on inverse modeling

Satellite remote sensing provides the only means of directly observing the entire surface of the Earth at regular spatial and temporal intervals

Impact of postfire logging on soil bacterial and fungal communities and soil biogeochemistry in a mixed-conifer forest in central Oregon

Postfire logging recoups the economic value of timber killed by wildfire, but whether such forest management activity supports or impedes forest recovery in stands differing in structure from historic conditions remains unclear. The aim of this study was to determine the impact of mechanical logging after wildfire on soil bacterial and fungal communities and other measures influencing soil productivity.KEYWORDS: T-RFLP, Wildfire, Community level physiological profiles, Soil bacterial and fungal communities, Postfire salvage logging, Soil chemical and physical propertiesThis is the publisher’s final pdf. The published article is copyrighted by Springer Science+Business Media and can be found at: http://www.springerlink.com/content/0032-079x/350/1-2

Can carbon isotopes be used to predict watershed-scale transpiration?

The Penman‐Monteith equation is often used to estimate transpiration, but an important limitation to this approach, especially for mountainous forested sites, is an accurate estimate of canopy conductance averaged over the area of interest (Gs). We propose a method for estimating watershed‐scale transpiration using estimates of Gs derived from measurements of stable isotopes. To estimate Gs, we first determined the isotopic composition of ecosystem respiration (δ¹³CER) as derived from the ¹²C:¹³C ratio of respired CO₂ entrained within nocturnal cold air drainage flows exiting the base of the watershed. An isotope‐derived estimate of recent canopy conductance over the entire watershed (Gs‐I) was derived using biophysical models. To estimate daily average transpiration, we applied Gs‐I and other measured environmental variables to the Penman‐Monteith equation. The results were compared with an independent measure of transpiration using the heat dissipation method at four locations within the watershed. Considering the large number of assumptions required for both estimates of transpiration, the two estimates were remarkably similar. The relationship between the values derived by the two techniques was statistically significant (p value 0.1), but the standard error was large (SE = 0.48). The results demonstrate that this technique holds promise, but the effects of potential limitations require further attention. The future research necessary to fully demonstrate the validity of this potentially promising method is discussed

Impacts of changed litter inputs on soil CO2 efflux in three forest types in central south China

We have defined Neutrosophic Over-/Under-/Off-Set and Logic for the first time in 1995 and published in 2007. During 1995-2016 we presented them to various national and international conferences and seminars. These new notions are totally different from other sets/logics/probabilities. We extended the neutrosophic set respectively to Neutrosophic Overset {when some neutrosophic component is > 1}, to Neutrosophic Underset {when some neutrosophic component is < 0}, and to Neutrosophic Offset {when some neutrosophic components are off the interval [0, 1], i.e. some neutrosophic component > 1 and other neutrosophic component < 0}. This is no surprise since our real-world has numerous examples and applications of over-/under-/off-neutrosophic components

Bias and uncertainty of δ \u3c sup\u3e 13 \u3c/sup\u3e CO \u3c inf\u3e 2 isotopic mixing models

Patterns in the isotopic signal (stable C isotope composition; δ13C) of respiration (δ13CR) have led to important gains in understanding the C metabolism of many systems. Contained within δ13CR is a record of the C source mineralized, the metabolic pathway of C and the environmental conditions during which respiration occurred. Because gas samples used for analysis of δ13CR contain a mixture of CO2 from respiration and from the atmosphere, two-component mixing models are used to identify δ13CR. Measurement of ecosystem δ13CR, using canopy airspace gas samples, was one of the first applications of mixing models in ecosystem ecology, and thus recommendations and guidelines are based primarily on findings from these studies. However, as mixing models are applied to other experimental conditions these approaches may not be appropriate. For example, the range in [CO2] obtained in gas samples from canopy air is generally less than 100 μmol mol-1, whereas in studies of respiration from soil, foliage or tree stems, the range can span as much as 10,000 μmol mol-1 and greater. Does this larger range in [CO2] influence the precision and accuracy of δ13CR estimates derived from mixing models? Does the outcome from using different regression approaches and mixing models vary depending on the range of [CO2]? Our research addressed these questions using a simulation approach. We found that it is important to distinguish between large (≥1,000 μmol mol-1) and small (≤100 μmol mol-1) ranges of CO2 when applying a mixing model (Keeling plot or Miller-Tans) and regression approach (ordinary least squares or geometric mean regression) combination to isotopic data. The combination of geometric mean regression and the Miller-Tans mixing model provided the most accurate and precise estimate of δ13CR when the range of CO2 is ≥1,000 μmol mol-1. © Springer-Verlag 2009

Can carbon isotopes be used to predict watershed-scale transpiration?

The Penman-Monteith equation is often used to estimate transpiration, but an important limitation to this approach, especially for mountainous forested sites, is an accurate estimate of canopy conductance averaged over the area of interest (Gs). We propose a method for estimating watershed-scale transpiration using estimates of Gs derived from measurements of stable isotopes. To estimate Gs, we first determined the isotopic composition of ecosystem respiration (δ13CER) as derived from the 12C:13C ratio of respired CO2 entrained within nocturnal cold air drainage flows exiting the base of the watershed. An isotope-derived estimate of recent canopy conductance over the entire watershed (Gs-I) was derived using biophysical models. To estimate daily average transpiration, we applied Gs-I and other measured environmental variables to the Penman-Monteith equation. The results were compared with an independent measure of transpiration using the heat dissipation method at four locations within the watershed. Considering the large number of assumptions required for both estimates of transpiration, the two estimates were remarkably similar. The relationship between the values derived by the two techniques was statistically significant (p value \u3c 0.01), the slope of the line (slope = 1.7) was not statistically different from 1 (p value \u3e 0.1), but the standard error was large (SE = 0.48). The results demonstrate that this technique holds promise, but the effects of potential limitations require further attention. The future research necessary to fully demonstrate the validity of this potentially promising method is discussed

Toward using δ \u3c sup\u3e 13 \u3c/sup\u3e C of ecosystem respiration to monitor canopy physiology in complex terrain

In 2005 and 2006, air samples were collected at the base of a Douglas-fir watershed to monitor seasonal changes in the δ13CO2 of ecosystem respiration (δ13CER). The goals of this study were to determine whether variations in δ13C ER correlated with environmental variables and could be used to predict expected variations in canopy-average stomatal conductance (G s). Changes in δ13CER correlated weakly with changes in vapor pressure deficit (VPD) measured 0 and 3-7 days earlier and significantly with soil matric potential (ψm) (P value \u3c 0.02) measured on the same day. Midday Gs was estimated using sapflow measurements (heat-dissipation method) at four plots located at different elevations within the watershed. Values of midday Gs from 0 and 3-7 days earlier were correlated with δ13CER, with the 5-day lag being significant (P value \u3c 0.05). To examine direct relationships between δ13CER and recent Gs, we used models relating isotope discrimination to stomatal conductance and photosynthetic capacity at the leaf level to estimate values of stomatal conductance ( Gs-I ) that would be expected if respired CO2 were derived entirely from recent photosynthate. We compared these values with estimates of Gs using direct measurement of transpiration at multiple locations in the watershed. Considering that the approach based on isotopes considers only the effect of photosynthetic discrimination on δ13CER, the magnitude and range in the two values were surprisingly similar. We conclude that: (1) δ13CER is sensitive to variations in weather, and (2) δ13CER potentially could be used to directly monitor average, basin-wide variations in G s in complex terrain if further research improves understanding of how δ13C ER is influenced by post-assimilation fractionation processes. © 2008 Springer-Verlag