Prediction Comparison of Stand Parameters and Two Ecosystem Services through New Growth and Yield Model System for Mixed Nothofagus Forests in Southern Chile

Forest managers need tools to predict the behavior of forests not only for the main stand parameters, such as basal area and volume, but also for ecosystem services such as timber volume and carbon sequestration. Useful tools to predict these parameters are growth and yield model systems with several possible options for modeling, such as the whole stand-level model, with or without diameter distribution generation, individual tree-level model, and compatibility models. However, those tools are scarce or developed mainly for forest plantations that are mostly located in the northern hemisphere. Thus, this study focuses on analyzing predictions of several growth and yield models built for native mixed Nothofagus forests from southern Chile, using the simulator Nothopack. A dataset of 19 permanent plots with three measurements were used for comparing the different models. Individual tree-level simulation presented the best goodness-of-fit statistics for stand parameters and ecosystem services. For example, the basal area gave an R2emp of 0.97 and 0.87 at 6 and 12 years of projection. However, the stand-level simulations with a generation of diameter distribution and both compatibility models showed satisfactory performance, both in accuracy and bias control. The simulator Nothopack, which has the capability of obtaining detailed outputs, is a useful tool to support management plans for these forest ecosystems.

Assessment of forest degradation condition in Natmataung National Park Watershed, Myanmar

Oo Y, Suanpaga W, Muenpong P. 2021. Assessment of forest degradation condition in Natmataung National Park Watershed, Myanmar. Biodiversitas 22: 1354-1362. Natmataung National Park (NTNP) is an important biodiversity hotspot in Myanmar, yet it is threatened by various anthropogenic activities, leading to deforestation and forest degradation. As such, the park needs to be restored to bring back its main function of conserving biodiversity. Ecological restoration in NTNP needs assessment of forest restoration potential through forest degradation condition. This research aimed: (1) to assess forest stand parameters of tree density, basal area, Above Ground Biomass (AGB), and Above Ground Carbon (AGC) at plot level and study area level through sampling with fixed area in the NTNP watershed, (2) to compare the accessed forest stand parameters of old-growth forest (OF) and secondary forest (SF) (per plot individual level and per stem individual level) and tree species richness and diversity of OF and SF (per plot individual level only) in order to know the forest degradation condition. A total of 69 square plots were sampled to achieve such aims. This study found two main results: (1) the estimation of stand parameters in both OF and SF at the plot level and study area level had acceptable statistical proration: (2) stand parameters at stem level had significant differences in which OF had overall higher values of parameters than in SF. Based on the results of this study, we recommend that the OF sites should be conserved through sustainable forest management, while the SF sites should be restored to mimic condition in OF through the implementation of assisted natural regeneration (ANR) with highest dominant native tree species, and the abandoned fallow lands should be restored using pioneer native tree species.

CALCULATION OF STAND PARAMETERS FOR REPAIR WORKS WITH VEHICLE BRAKE SYSTEM

В статье представлена принципиальная схема и некоторые расчеты по совершенствованию универсального тормозного стенда для автомобилей, предназначенного для контроля эффективности торможения и устойчивости автотранспортных средств при торможении, в том числе легковых, грузовых автомобилей, автобусов, а также многоосных и полноприводных автомобилей с осевой нагрузкой до 15000 кг. Принцип действия стендов основан на преобразовании тензорезисторными датчиками реактивных моментов тормозных сил, возникающих при торможении колес автомобиля, а также силы тяжести, создаваемой осью автомобиля на роликовые установки в аналоговые электрические сигналы. В качестве измерительного датчика предполагается применение тензорезисторного силоизмерительного устройства, преобразующих реактивные моменты тормозных сил, возникающих при торможении колес автомобиля, а также силы тяжести, создаваемой осью автомобиля на роликовые установки в аналоговые электрические сигналы. Скорость вращения колес автомобиля и фиксация момента полного торможения контролируется следящими роликами с датчиками скорости вращения. Сигналы от тензорезисторных датчиков поступают в аналого-цифровой преобразователь (АЦП), а затем в микропроцессорный контроллер и ПЭВМ (персональная электронно-вычислительная машина), где они автоматически обрабатываются по специальной программе. Основным требованием, предъявляемым к конструкции стенда является возможность самозатягивания при проворачивании барабана.