Soil methane sink capacity response to a long-term wildfire chronosequence in Northern Sweden

Boreal forests occupy nearly one fifth of the terrestrial land surface and are recognised as globally important regulators of carbon (C) cycling and greenhouse gas emissions. Carbon sequestration processes in these forests include assimilation of CO2 into biomass and subsequently into soil organic matter, and soil microbial oxidation of methane (CH4). In this study we explored how ecosystem retrogression, which drives vegetation change, regulates the important process of soil CH4 oxidation in boreal forests. We measured soil CH4 oxidation processes on a group of 30 forested islands in northern Sweden differing greatly in fire history, and collectively representing a retrogressive chronosequence, spanning 5000 years. Across these islands the build-up of soil organic matter was observed to increase with time since fire disturbance, with a significant correlation between greater humus depth and increased net soil CH4 oxidation rates. We suggest that this increase in net CH4 oxidation rates, in the absence of disturbance, results as deeper humus stores accumulate and provide niches for methanotrophs to thrive. By using this gradient we have discovered important regulatory controls on the stability of soil CH4 oxidation processes that could not have not been explored through shorter-term experiments. Our findings indicate that in the absence of human interventions such as fire suppression, and with increased wildfire frequency, the globally important boreal CH4 sink could be diminished

THE RELATIONSHIP BETWEEN POSTURE STABILITY AND ONE-HAND CATCHING

The purpose of this study was to examine the influence of posture stability on one-hand catching in skilled adults. Ten female PE major college students participated in the experiment. They practiced the stabilometer task 20 trials a day, 3 days a week for 2 weeks. The balancing time, number of balls caught, as well as the movement kinematics of the pre and post-test data were analyzed. The results show that the time of balance improved through practice, the frequency and the amplitude of the platform changed after practice. The number of balls caught was only perturbed by the stabilometer before practice. Principle component analysis (PCA) on the kinematic data show that the number of components did not decrease after practice, but the content of each component changed through practice. We conclude that postural stability only influences the well-retained motor skills at the beginning of practice; it is the performance of the newly learned skill that suffers from perturbations

A proteomic study of TAR-RNA binding protein (TRBP)-associated factors

<p>Abstract</p> <p>Background</p> <p>The human TAR RNA-binding protein, TRBP, was first identified and cloned based on its high affinity binding to the small hairpin trans-activation responsive (TAR) RNA of HIV-1. TRBP has more recently been found to be a constituent of the RNA-induced silencing complex (RISC) serving as a Dicer co-factor in the processing of the ~70 nucleotide pre-microRNAs(miRNAs) to 21-25 nucleotide mature miRNAs.</p> <p>Findings</p> <p>Using co-immunoprecipitation and protein-identification by mass spectrometry, we characterized intracellular proteins that complex with TRBP. These interacting proteins include those that have been described to act in protein synthesis, RNA modifications and processing, DNA transcription, and cell proliferation.</p> <p>Conclusions</p> <p>Our findings provide a proteome of factors that may cooperate with TRBP in activities such as miRNA processing and in RNA interference by the RISC complex.</p

The nuclear envelopathies and human diseases

The nuclear envelope (NE) consists of two membrane layers that segregate the nuclear from the cytoplasmic contents. Recent progress in our understanding of nuclear-lamina associated diseases has revealed intriguing connections between the envelope components and nuclear processes. Here, we review the functions of the nuclear envelope in chromosome organization, gene expression, DNA repair and cell cycle progression, and correlate deficiencies in envelope function with human pathologies

Net soil carbon balance in afforested peatlands and separating autotrophic and heterotrophic soil CO₂ effluxes

Peatlands are a significant global carbon (C) store, which can be compromised by drainage and afforestation. Quantifying the rate of C loss from peat soils under forestry is challenging, as soil CO2 efflux includes both CO2 produced from heterotrophic peat decomposition and CO2 produced by tree roots and associated fungal networks (autotrophic respiration). We experimentally terminated autotrophic below-ground respiration in replicated forest plots by cutting through all living tree roots (trenching) and measured soil surface CO2 flux, litter input, litter decay rate, and soil temperature and moisture over 2 years. Decomposition of cut roots was measured and CO2 fluxes were corrected for this, which resulted in a large change in the fraction heterotrophic : autotrophic flux, suggesting that even 2 years after trenching decaying root biomass makes significant contributions to the CO2 flux. Annual peat decomposition (heterotrophic CO2 flux) was 115 \ub116 g C m−2 yr−1, representing ca. 40 % of total soil respiration. Decomposition of needle litter is accelerated in the presence of an active rhizosphere, indicating a priming effect by labile C inputs from roots. This suggests that our estimates of peat mineralization in our trenched plots are conservative and underestimate overall rates of peat C loss. Considering also input of litter from trees, our results indicate that the soils in these 30-year-old drained and afforested peatlands are a net sink for C, since substantially more C enters the soil organic matter than is decomposed heterotrophically. This study does not account for fluvial C fluxes, which represent a small flux compared to the CO2 soil efflux; further, root litter and exudate deposition could be a significant C source that is only partially sampled by our approach, adding to these plantations being a potential carbon sink. However, the C balance for these soils should be taken over the lifespan of the trees, in order to determine if the soils under these drained and afforested peatlands are a sustained sink of C or become a net source over longer periods of forestry

Assessing Forest Carbon Accumulation Potential Across Different Treatments using Field Inventory Data

Deforestation and forest degradation lead to an increase in the level of carbon in the atmosphere and disrupted the global carbon cycle. The tropical forest has received a lot of interest since it contributes around 60% of the total global forest carbon. By enhancing carbon sink, tropical forests have a great potential in mitigating climate change. Assessing aboveground biomass (AGB) and carbon stock through field inventories is crucial for this purpose as it provides the most accurate result. The research was conducted at Danum Valley Conservation Area and INFAPRO in Sabah, Malaysia. An earlier study over 35 years ago at this site suggests that restored forests accrue AGB at twice the rate of regenerating forests, though the cause of this difference between treatments is unclear. Thus, this study will focus on three principal study sites which are restored, naturally regenerating and old-growth forests to determine the forest’s potential to sequester and store carbon in the forest ecosystem. These three sites were chosen because it is a well-established plot from the earlier inventory over the last seven years. The field measuring method is a non-destructive methodology. Tree parameters such as diameter at breast height (DBH), tree height and tree species diversity were collected for calculating AGB using a species-specific allometric equation. Results showed a positive correlation between tree species, diameter at breast height, and biomass/carbon stock across three different forest treatments. The active restoration increases up to 151% carbon stock whilst the old-growth forest increased by 34% and natural regeneration increased by 73%, which active restoration can be the best solution for forest treatment. The outcome of this study will increase the ability of forest authorities and the Malaysian government to effective monitoring of carbon stock for establishing reliable standard guidelines in measuring deforestation and forest degradation toward achieving sustainable forest management

Spatial variations in heterotrophic respiration from oil palm plantations on tropical peat soils

&lt;p&gt;Oil palm plantations growing on peat soil are associated with high soil CO&lt;sub&gt;2&lt;/sub&gt; emissions. Oil palm plantations are set up with regular spatial patterns consisting of different surface management microforms: bare soil harvest paths, frond piles, cover plants and drainage ditches. Currently, there is limited understanding about the extent that this spatial variation impacts soil carbon losses, in part due to the challenges of partitioning peat oxidation from total soil respiration. We explored this spatial variation by measuring total soil respiration (R&lt;sub&gt;tot&lt;/sub&gt;), root density and environmental variables at 210 locations. Measurements were taken along transects going from the base of oil palms into the different microforms. R&lt;sub&gt;tot&lt;/sub&gt; was partitioned into root respiration (R&lt;sub&gt;a&lt;/sub&gt;) and heterotrophic respiration (R&lt;sub&gt;h&lt;/sub&gt;) using two different methods: (i) a “distance from palm” method (which utilizes the fluxes taken from soil with minimal root density) and (ii) a “linear regression” method (which models root density and R&lt;sub&gt;tot&lt;/sub&gt;, using the regression intercept for R&lt;sub&gt;h&lt;/sub&gt;). Here, the distance from palm partitioning method gave higher R&lt;sub&gt;h&lt;/sub&gt; estimates than the linear regression method. R&lt;sub&gt;h&lt;/sub&gt; varied significantly between the different palms used in the assessment but did not show significant spatial variation aside from this. R&lt;sub&gt;tot&lt;/sub&gt; and R&lt;sub&gt;a&lt;/sub&gt; were highest next to the palm and decreased with increasing distance from the palm. R&lt;sub&gt;tot&lt;/sub&gt; and R&lt;sub&gt;a&lt;/sub&gt; also showed significant spatial variation between the different surface management microforms, with each giving significantly higher fluxes below the frond piles near the drainage ditches than from below the frond piles near the cover plants. Area-weighted upscaling gave plantation best estimates of R&lt;sub&gt;tot&lt;/sub&gt;, R&lt;sub&gt;h&lt;/sub&gt;, R&lt;sub&gt;a&lt;/sub&gt; of 0.158 \ub1 0.016, and 0.130 \ub1 0.036 and 0.029 \ub1 0.030 g CO&lt;sub&gt;2&lt;/sub&gt;-C m&lt;sup&gt;−2&lt;/sup&gt; h&lt;sup&gt;−1&lt;/sup&gt;, respectively. We conclude that spatial patterns impact root density, R&lt;sub&gt;a&lt;/sub&gt; and R&lt;sub&gt;tot&lt;/sub&gt; fluxes but not R&lt;sub&gt;h&lt;/sub&gt; fluxes.&lt;/p&gt

Major and persistent shifts in below-ground carbon dynamics and soil respiration following logging in tropical forests

Soil respiration is the largest carbon efflux from the terrestrial ecosystem to the atmosphere, and selective logging influences soil respiration via changes in abiotic (temperature, moisture) and biotic (biomass, productivity, quantity and quality of necromass inputs) drivers. Logged forests are a predominant feature of the tropical forest landscape, their area exceeding that of intact forest. We quantified both total and component (root, mycorrhiza, litter, and soil organic matter, SOM) soil respiration in logged (n=5) and old-growth (n=6) forest plots in Malaysian Borneo, a region which is a global hotspot for emission from forest degradation. We constructed a detailed below-ground carbon budget including organic carbon inputs into the system via litterfall and root turnover. Total soil respiration was significantly higher in logged forests than in old-growth forests (14.3 \ub1 0.23 and 12.7 \ub1 0.60 Mg C ha-1 year-1, respectively, p=0.037). This was mainly due to the higher SOM respiration in logged forests (55% \ub1 3.1% of the total respiration in logged forests vs. 50% \ub1 3.0% in old-growth forests). In old-growth forests, annual SOM respiration was equal to the organic carbon inputs into the soil (difference between SOM respiration and inputs 0.18 Mg C ha-1 year-1, with 90% confidence intervals of -0.41 and 0.74 Mg C ha-1 year-1), indicating that the system is in equilibrium, while in logged forests SOM respiration exceeded the inputs by 4.2 Mg C ha-1 year-1 (90% CI of 3.6 and 4.9 Mg C ha-1 year-1), indicating that the soil is losing carbon. These results contribute towards understanding the impact of logging on below-ground carbon dynamics, which is one of the key uncertainties in estimating emissions from forest degradation. This study demonstrates how significant perturbation of the below-ground carbon balance, and consequent net soil carbon emissions, can persist for decades after a logging event in tropical forests

Effects of Biochar from Oil Palm Biomass on Soil Properties and Growth Performance of Oil Palm Seedlings

Fertilizer is the most expensive input in oil palm cultivation. Biochar can be used to improve the nutrient use efficiency, reducing the cost of fertilizer. Application of biochar from oil palm biomass onto oil palms has been scarcely studied. This paper reports the effects of empty fruit bunch (EFB) and palm kernel shell (PKS) biochar on the soil properties and growth performance of oil palm seedlings. The EFB and PKS biochar used were slightly acidic to neutral (pH 6.08 – 7.10) with the former exhibiting well-defined macropores. The seedlings ameliorated with EFB biochar demonstrated improved plant height and biomass with increasing biochar dosage. Marked improvements in uptake of phosphorus, magnesium, calcium and boron were also observed in the palm seedlings treated with EFB biochar. This was associated with the enhanced soil cation exchange capacity (CEC) upon biochar treatment. These positive effects of EFB biochar on plants and soil however were not recorded in the treatment with PKS biochar as the biochar was characterized with marginal porous structures and poor CEC properties. The study concluded that the stimulatory effects of EFB biochar on soil properties and plant growth were primarily governed by the biochar morphology and its cation exchange properties

Short- and long-term carbon emissions from oil palm plantations converted from logged tropical peat swamp forest

Need for regional economic development and global demand for agro-industrial commodities has resulted in large-scale conversion of forested landscapes to industrial agriculture across South East Asia. However, net emissions of CO2 from tropical peatland conversions may be significant and remain poorly quantified, resulting in controversy around the magnitude of carbon release following conversion. Here we present long term, whole ecosystem monitoring of carbon exchange from two oil palm plantations on converted tropical peat swamp forest. Our sites compare a newly converted oil palm plantation (OPnew) to a mature oil palm plantation (OPmature) and combine them in the context of existing emission factors. Mean annual net emission (NEE) of CO2 measured at OPnew during the conversion period (137.8 Mg CO2 ha-1 yr -1) were an order of magnitude lower during the measurement period at OPmature (17.5 Mg CO2 ha-1 yr-1). However, mean water table depth (WTD) was shallower (0.26 m) than a typical drainage target of 0.6 m suggesting our emissions may be a conservative estimate for mature plantations, mean WTD at OPnew was more typical at 0.54 m. Reductions in net emissions were primarily driven by increasing biomass accumulation into highly productive palms. Further analysis suggested annual peat carbon losses of 24.9 Mg CO2-C ha-1 yr-1 over the first 6 years, lower than previous estimates for this early period from subsidence studies, losses reduced to 12.8 Mg CO2-C ha-1 yr-1 in the later, mature phase. Despite reductions in NEE and carbon loss over time, the system remained a large net source of carbon to the atmosphere after 12 years with the remaining 8 years of a typical plantation?s rotation unlikely to recoup losses. These results emphasise the need for effective protection of tropical peatlands globally and strengthening of legislative enforcement where moratoria on peatland conversion already exist