The Ecosystem as Super-Organ/ism, Revisited: Scaling Hydraulics to Forests under Climate Change.

Classic debates in community ecology focused on the complexities of considering an ecosystem as a super-organ or organism. New consideration of such perspectives could clarify mechanisms underlying the dynamics of forest carbon dioxide (CO2) uptake and water vapor loss, important for predicting and managing the future of Earth's ecosystems and climate system. Here, we provide a rubric for considering ecosystem traits as aggregated, systemic, or emergent, i.

The ecosystem wilting point defines drought response and recovery of a Quercus-Carya forest.

Soil and atmospheric droughts increasingly threaten plant survival and productivity around the world. Yet, conceptual gaps constrain our ability to predict ecosystem-scale drought impacts under climate change. Here, we introduce the ecosystem wilting point (Ψ ), a property that integrates the drought response of an ecosystem's plant community across the soil-plant-atmosphere continuum.

The xylem of anisohydric Quercus alba L. is more vulnerable to embolism than isohydric codominants.

The coordination of plant leaf water potential (Ψ ) regulation and xylem vulnerability to embolism is fundamental for understanding the tradeoffs between carbon uptake and risk of hydraulic damage. There is a general consensus that trees with vulnerable xylem more conservatively regulate Ψ than plants with resistant xylem. We evaluated if this paradigm applied to three important eastern US temperate tree species, Quercus alba L.

Mild water and salt stress improve water use efficiency by decreasing stomatal conductance via osmotic adjustment in field maize.

Water and salt stress often occur simultaneously in heavily irrigated arid agricultural areas, yet they are usually studied in isolation. To understand the physiological bases of water use efficiency (WUE) of field-grown maize (Zea mays) at multi-scales under combined water and salt stress, we investigated the joint effects of water and salt stress on physiology, growth, yield, and WUE of two genotypes (XY335 and ZD958). We measured leaf stomatal conductance (g), net photosynthesis rate (A) and hydraulic traits, whole-plant growth and water use (ET), and final biomass and grain yield.

Detecting forest response to droughts with global observations of vegetation water content.

Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more.

Top-Down Constraints on Methane Point Source Emissions From Animal Agriculture and Waste Based on New Airborne Measurements in the U.S. Upper Midwest.

Agriculture and waste are thought to account for half or more of the U.S. anthropogenic methane source.

Eastern US deciduous tree species respond dissimilarly to declining soil moisture but similarly to rising evaporative demand.

Hydraulic stress in plants occurs under conditions of low water availability (soil moisture; θ) and/or high atmospheric demand for water (vapor pressure deficit; D). Different species are adapted to respond to hydraulic stress by functioning along a continuum where, on one hand, they close stomata to maintain a constant leaf water potential (ΨL) (isohydric species), and on the other hand, they allow ΨL to decline (anisohydric species). Differences in water-use along this continuum are most notable during hydrologic stress, often characterized by low θ and high D; however, θ and D are often, but not necessarily, coupled at time scales of weeks or longer, and uncertainty remains about the sensitivity of different water-use strategies to these variables.

Does overwintering change the inoculum effect on methane emissions from stored liquid manure?

Greenhouse gas (GHG) emissions, especially methane (CH ), from manure storage facilities can be substantial. Methane production requires adapted microbial communities ("inoculum") to be present in the manure. Complete removal of liquid dairy manure (thus removing all inoculum) from storage tanks in the spring has been shown to significantly reduce CH emissions over the following warm season.

Error characterization of methane fluxes and budgets derived from a long-term comparison of open- and closed-path eddy covariance systems.

Wetlands represent the dominant natural source of methane (CH) to the atmosphere. Thus, substantial effort has been spent examining the CH budgets of global wetlands continuous ecosystem-scale measurements using the eddy covariance (EC) technique. Robust error characterization for such measurements, however, remains a major challenge.

Sun-induced Chl fluorescence and its importance for biophysical modeling of photosynthesis based on light reactions.

Recent progress in observing sun-induced Chl fluorescence (SIF) provides an unprecedented opportunity to advance photosynthesis research in natural environments. However, we still lack an analytical framework to guide SIF studies and integration with the well-developed active fluorescence approaches. Here, we derive a set of coupled fundamental equations to describe the dynamics of SIF and its relationship with C and C photosynthesis.

Source Partitioning of Methane Emissions and its Seasonality in the U.S. Midwest.

The methane (CH) budget and its source partitioning are poorly constrained in the Midwestern United States. We used tall tower (185 m) aerodynamic flux measurements and atmospheric scale factor Bayesian inversions to constrain the monthly budget and to partition the total budget into natural (e.g.

Nitrous oxide emissions are enhanced in a warmer and wetter world.

Nitrous oxide (NO) has a global warming potential that is 300 times that of carbon dioxide on a 100-y timescale, and is of major importance for stratospheric ozone depletion. The climate sensitivity of NO emissions is poorly known, which makes it difficult to project how changing fertilizer use and climate will impact radiative forcing and the ozone layer. Analysis of 6 y of hourly NO mixing ratios from a very tall tower within the US Corn Belt-one of the most intensive agricultural regions of the world-combined with inverse modeling, shows large interannual variability in NO emissions (316 Gg NO-N⋅y to 585 Gg NO-N⋅y).

Greenhouse Gas Emissions from Stored Dairy Slurry from Multiple Farms.

A significant need exists to improve our understanding of the extent of greenhouse gas emissions from the storage of livestock manure to both improve the reliability of inventory assessments and the impact of beneficial management practice adoption. Factors affecting the extent and variability of greenhouse gas emissions from stored dairy manure were investigated. Emissions from six slurries stored in clean concrete tanks under identical "warm-season" conditions were monitored consecutively over 173 d (18°C average air temperature).

Performance of Seasonally and Continuously Loaded Constructed Wetlands Treating Dairy Farm Wastewater.

A 2-yr study compared the performance of seasonally and continuously loaded constructed wetlands treating dairy farm wastewater. One wetland was loaded during the growing season (GS) periods only, while the other was continuously loaded. Weekly samples were analyzed for 5-d biochemical oxygen demand (BOD), total suspended solids (TSS), total Kjeldahl N (TKN), total ammoniacal N (TAN), total P (TP), and .

Indirect nitrous oxide emissions from streams within the US Corn Belt scale with stream order.

N2O is an important greenhouse gas and the primary stratospheric ozone depleting substance. Its deleterious effects on the environment have prompted appeals to regulate emissions from agriculture, which represents the primary anthropogenic source in the global N2O budget. Successful implementation of mitigation strategies requires robust bottom-up inventories that are based on emission factors (EFs), simulation models, or a combination of the two.

Δ(9) desaturase protein expression and fatty acid composition of longissimus dorsi muscle in lambs fed green herbage or concentrate with or without added tannins.

The aims of this study were to investigate the effect of feeding system and of supplementation of tannins (8.93% DM) on the relationship between intramuscular fat content, fatty acid composition and Δ(9)desaturase (Δ(9)d) protein expression in longissimus dorsi muscle of lamb. Twenty-eight Comisana lambs (age 45days) were fed either vetch (Vicia sativa) or concentrate.

Regulation of CYP2A6 protein expression by skatole, indole, and testicular steroids in primary cultured pig hepatocytes.

CYP2A6 is one of the enzymes involved in the hepatic metabolism of a naturally produced compound, skatole, in the pig. Low CYP2A6 activity has been linked to excessive accumulation of skatole in pig adipose tissue and development of the phenomenon "boar taint." CYP2A6 activity varies between male and female animals, suggesting the involvement of sex hormones in regulation of the enzyme activity and/or expression.

Use of a particulate extracellular matrix bioscaffold for treatment of acquired urinary incontinence in dogs.

Objective: To evaluate use of a particulate bioscaffold consisting of the extracellular matrix (ECM) of the urinary bladder from pigs for treatment of acquired urinary incontinence in dogs resistant to medical treatment.

Design: Case series.

Animals: 9 female dogs with acquired urinary incontinence.

Dietary manipulation of fatty acid composition in lamb meat and its effect on the volatile aroma compounds of grilled lamb.

The effect on lamb muscle of five dietary supplements high in polyunsaturated fatty acids (PUFA) was measured. The supplements were linseed oil, fish oil, protected lipid (high in linoleic acid (C18:2 n-6) and α-linolenic acid (C18:3 n-3)), fish oil/marine algae (1:1), and protected lipid/marine algae (1:1). Eicosapentaenoic acid (C20:5 n-3) and docosahexaenoic acid (C22:6 n-3) were found in the highest amounts in the meat from lambs fed diets containing algae.

The pig CYP2E1 promoter is activated by COUP-TF1 and HNF-1 and is inhibited by androstenone.

Functional analysis of the pig cytochrome P4502E1 (CYP2E1) promoter identified two major activating elements. One corresponded to the hepatic nuclear factor 1 (HNF-1) consensus binding sequence at nucleotides -128/-98 and the other was located in the region -292/-266. The binding of proteins in pig liver nuclear extracts to a synthetic double-stranded oligonucleotide corresponding to this more distal activating sequence was studied by electrophoretic mobility shift assay.

Restriction of dietary energy and protein induces molecular changes in young porcine skeletal muscles.

Little is known about the molecular changes in response to dietary restriction (energy and/or protein) in young growing skeletal muscles. To profile such changes and to gain insights into the signaling molecules that could mediate the diet effects, a dedicated porcine skeletal muscle cDNA-microarray approach was used to characterize differential muscle gene expression between conventionally fed and diet-restricted (20% less protein and 7% less energy) growing pigs, reared from 9 to 21 wk of age. In both red and white muscles, diet restriction resulted in the accumulation of significantly more intramuscular fat, and in the increased expression of genes involved in substrate (protein, glycogen, and lipid) turnover, in translation and mitochondrial function, and in raising glycolytic and oxidative phosphorylation potentials.

Characterisation of androstenone metabolism in pig liver microsomes.

Androstenone (5 alpha-androst-16-en-3-one) is a steroid pheromone produced in the testis. Excessive accumulation of androstenone together with skatole (3-methyl-indole) in the adipose tissue of some male pigs leads to "boar taint". In isolated pig hepatocytes androstenone represses the expression of cytochrome P450IIE1 (CYP2E1), the enzyme principally responsible for skatole metabolism.