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© iForest -Biogeosciences and Forestry IntroductionOne of the most meaningful attributes used to describe forests both as a resource and as an ecosystem is biomass density per unit area. Nondestructive measurements of tree biomass are not possible -at least if the term "measurement" is used in its generic sense. Therefore, models are established based on destructively sampled trees to estimate total biomass. Tree variables commonly used for such models are the diameter at breast height (DBH, measured at 1.3 m height) or DBH in combination with total tree height. These allometric relationships (from the ancient Greek word "αλλος" = "other") are commonly modeled as power functions (Niklas 1994, West et al. 1999a, Zianis & Mencuccini 2004, Pilli et al. 2006, Fehrmann & Kleinn 2006 of the form M = aDb, where M is the mass of dry matter, D is the diameter, b is the allometric scaling factor and a is a coefficient determining the allometric intercept (Parresol 1999). The general model formulation also complies with assumptions of process models in plant allometry that are based on considerations on the hydraulic architecture and structural design of vascular plants and derive a particular scaling exponent of 8/3 (West et al. 1997, 1999a, 1999b, Enquist 2002, Niklas 2004. Total tree biomass is expected to scale proportionally to the conducting tissue that determines the metabolic rate.The predicted biomass value, however, is not to be understood as a "measurement", but rather as "model-based estimation", carrying not only measurement errors (introduced by the measurement of the input variables to the model used) but also model errors (Clark & Kellner 2012). In many old-growth natural and close-to-natural forest types, in particular tropical forests, the relatively few very large trees fix a large amount of carbon (Stephenson et al. 2014) and contribute a considerable share to the stand basal area and total biomass: "Large trees drive forest aboveground biomass variation in moist lowland forests across the tropics" (Slik et al. 2010).In tropical forests the largest proportion of buttressed trees is usually among the emergent trees in the upper crown layer. These huge trees frequently show very irregular non-convex shapes (Chapman et al. 1998, Mehedi et al. 2012, Cushman et al. 2014. Clark (2002) reports for a Costarican lowland rain forest that about 52% of the stands' above ground woody biomass was constituted by trees whose diameter needed to be measured above stem irregularities. A study in southwest China shows that the percentage of buttressed trees is highest in the larger diameter classes (He et al. 2013). Buttresses are complex features that are regarded as an adaptation to poor tropical soils, enabling trees to form a flat root system in the upper, nutrient richer soil layers while maintaining their mechanical stability and anchorage (Richards 1952, Richter 1984, Ennos 1993, Crook et al. 1997, Newbery et al. 2009, Niklas 2013. Usually Dipterocarpaceae, Ligumninosae and Sterculiaceae show a greater tendency to p...

The Riau Province has been suffering from the highest deforestation rate in Sumatra, Indonesia. Many and various factors haved been discussed as causes of different deforestation types. This research is focused on evaluating the spatial pattern of deforestation in a specific location respresenting a typical deforestation in Riau. The main objective of this study to identify spatial metrics to describe deforestation that occurred in Kampar and Indragiri was Hulu regencies.The study divided the deforestation process into 3 periods of observation, .

Selling system of sengon (Paraserianthes falcataria) timber in community forests without using appropriate tree L. volume models may generate profit loss for the farmers. The objectives of this study were to develop volume models of sengon and to evaluate the profit losses of commonly practiced techniques for selling the sengon timber in community forest. The result showed that the proposed volume model can be used accurately to estimate the volume of sengon trees in the community forest by measuring tree diameters. This study confirmed that the selling system based on per log and total stand area caused profit losses of 24.99% and 32.19% respectively, to the farmers. To avoid such disadvantages, therefore the use of the proposed volume model is recommended to facilitate accurate estimation of the volume of sengon trees.

<p>Utilization of very high-resolution images becomes a new trend in forest management, particularly in the detection and identification of forest stand variables. This paper describes the use of mean-shift segmentation algorithm on unmanned aerial vehicles (UAV) images to measure crown closure of nypa (Nypa fructicans) and gap. The 27 combinations of the parameter values such as spatial radius (hs), range radius (hr), and minimum region size (M). Gap detection and nypa crown closure measurements were performed using a hybrid between pixel-based (maximum likelihood classifier) and object-based approaches (segmentation).  For evaluation of the approach performance, the accuracy assessment was done by comparing object-based classification results (segmentation) and visual interpretation (ground check). The study found that the best combination of segmentation parameter was the combination of hs 10, hr 10 and M 50, with the overall accuracy of 76,6% and kappa accuracy of 55.7%.</p>