Non-flooded riparian Amazon trees are a regionally significant methane source

Inundation-adapted trees were recently established as the dominant egress pathway for soil-produced methane (CH 4 ) in forested wetlands. This raises the possibility that CH 4 produced deep within the soil column can vent to the atmosphere via tree roots even when the water table (WT) is below the surface. If correct, this would challenge modelling efforts where inundation often defines the spatial extent of ecosystem CH 4 production and emission. Here, we examine CH 4 exchange on tree, soil and aquatic surfaces in forest experiencing a dynamic WT at three floodplain locations spanning the Amazon basin at four hydrologically distinct times from April 2017 to January 2018. Tree stem emissions were orders of magnitude larger than from soil or aquatic surface emissions and exhibited a strong relationship to WT depth below the surface (less than 0). We estimate that Amazon riparian floodplain margins with a WT < 0 contribute 2.2–3.6 Tg CH 4 yr −1 to the atmosphere in addition to inundated tree emissions of approximately 12.7–21.1 Tg CH 4 yr −1 . Applying our approach to all tropical wetland broad-leaf trees yields an estimated non-flooded floodplain tree flux of 6.4 Tg CH 4 yr −1 which, at 17% of the flooded tropical tree flux of approximately 37.1 Tg CH 4 yr −1 , demonstrates the importance of these ecosystems in extending the effective CH 4 emitting area beyond flooded lands. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 2)'.

Covariance Generalized Linear Models: An Approach for Quantifying Uncertainty in Tree Stem Taper Modeling

A natural dependence among diameters measured within-tree is expected in taper data due to the hierarchical structure. The aim of this paper was to introduce the covariance generalized linear model (CGLM) framework in the context of forest biometrics for Pinus taeda stem form modeling. The CGLMs are based on marginal specification, which requires a definition of the mean and covariance components. The tree stem mean profiles were modeled by a nonlinear segmented model. The covariance matrix was built considering four strategies of linear combinations of known matrices, which expressed the variance or correlations among observations. The first strategy modeled only the variance of the diameters over the stem as a function of covariates, the second modeled correlation among observations, the third was defined based on a random walk model, the fourth was based on a structure similar to a mixed-effect model with a marginal specification, and the fourth was a traditional mixed-effect model. Mean squared error and bias showed that the approaches were similar for describing the mean profile for fitting and validation dataset. However, uncertainties expressed by confidence intervals of the relative diameters were significant and related to the matrix covariance structures of the CGLMs. Study Implications: We proposed stem taper modeling based on a new class of statistical models. Covariance generalized linear models allow quantification of the stem dynamic by using a nonlinear model. Uncertainty estimates are performed on a covariance matrix given by a linear combination of known matrices. The matrices enable modeling of the nonconstant variance as well as the several correlation patterns, resulting in a framework more flexible and robust than traditional approaches usually applied for stem taper modeling. For practical purposes, uncertainty modeling can improve forest management planning, because the production limits by timber assortments are more reliable due to the confidence intervals derived from an appropriate uncertainty analysis.

The pattern of germination of teak mistletoe seeds in relation with parasitism

The objectives of this research are to test the initial viability and germination pattern of teak mistletoe seeds, namely Dendrophthoe pentandra and Macrosolen tetragonus in associated with parasitism. Research results showed that the pattern of D. pentandra germination was different from that of M. tetragonus. The germination process of D. pentandra showed incomplete development of germination morphology, marked by an absence of development or growth of hypocotyl and cotyledon. Parasitism was more dominant in D. pentandra, supported by the fact that the sum of mean germination day (RH) in the stem of teak seedling was faster (17.54±2.77 days), as compared with that of M. tetragonus (35.13±1.76 days), although mortality of M. tetragonus seedlings was very low (±3%), whereas that of D. pentandra was fairly high (±34%). It was related to the life cycle of M. tetragonus, which was longer than that of D. pentandra. In the attachment of seeds in the standing tree stems, it was proven that the germination percentage (%K) of D. pentandra (38.5%) was higher than that of M. tetragonus (11.1%). Seed germination of D. pentandra from bird feces also showed that %K (46.4%) was higher than seed attachment in tree stem, including M. tetragonus. It was supposed that there was a correlation between the easiness of germination and parasitism character in teak mistletoes. It was considered that parasitism of D. pentandra was more prominent than that of M. tetragonus in a teak host.

Modeling structure of Scots pine stems volume by grade categories using stochastic process

The study highlights methodological aspects of predicting stem volume of merchantable Scots pine trees by grade categories using distribution models of different quality zones along stems. The study is based on empirical data collected in the mature stand during clear-cut harvesting. In total it includes measurements of 245 tree stems for which sequence and lengths of different quality categories were evaluated. A semi-Markov model was applied to characterize a random process of height-relevant co-occurrence and length of merchantable wood, firewood, and residues. The model was determined by the following parameters: 1) input occurrence probabilities of specific grade category in the butt section of tree stems (initial state of the system); 2) distribution matrix of grade categories by lengths; 3) matrix with transition probabilities between grade classes on different stem heights. In this study, we considered the process in which the initial state of the system was associated with merchantable wood which was true for most pine stems. We used beta-function to model lengths of grade categories which parameters were fitted using relative stems height. We also used empirical data to calculate probabilities of transition between merchantable wood, firewood, and residuals along pine stems. The analysis indicates that the length distribution of merchantable wood and firewood depends on the relative height where the grade is observed, and total tree stem height. Thus, we identified four zones where the function of beta-distribution was used to model lengths of each grade category with customized parameters depending on the relative height of their location on tree stem. As a result, we developed a methodology that can be used to simulate datasets with tree stem characteristics, and further to predict the distribution of volume by grade categories depending on their diameters, heights, and merchantability. It is worth noting that our study is focused merely on merchantable pine stems, and one should expect another relationship for stems of different tree species as well as for merchantable pulpwood trees. Given the new standard for merchantable wood classification adopted in Ukraine, the developed methodology is suitable for updating existing tables of distribution of tree stem volumes by wood grade categories.

Intriguing aural foreign body and algorithm of management of foreign body

Foreign body (FB) in the external auditory canal is more common among the paediatric age group compared with adult patients and it may be deposited in various ways. An accidental animate aural FB is reported to be commonly encountered in adults whereas inanimate FBs are likely to be found among adult patients with learning disability. An elderly man presented with accidental penetration of rattan tree stem into his ear while gardening. Removal of a FB from the external auditory canal requires expertise as deep penetration of a FB into the middle and inner ear may lead grave complications, especially when overzealous removal is attempted by nonear, nose and throat (ENT) personnel. This case emphasises on the importance of awareness of meticulous removal of a FB under proper visualisation so as to avoid unnecessary complications. Additionally, we propose an algorithm for proper removal of aural FB in an acute care setting.