The Pattern Recognition of Small-Scale Privately-Owned Forest in Ciamis Regency, West Java, Indonesia

Small-scale Privately-owned Forest (SSPF) has various patterns identification, based on the stand structure and species composition. The recognition and classification of the SSPF cropping patterns are required for further planning and policy development. Therefore, this study aims to classify the cropping pattern of SSPF in Ciamis Regency, West Java Province, Indonesia. The data were collected by observing the stand structure and species composition of 150 plots of land, encompassing three Sub-districts representing the central, northern, and southern regions of Ciamis Regency. The four categorical variables include tree species composition, age, spatial distribution, and intercropping pattern. While the two continuous variables were stand density and basal area. The patterns obtained were classified based on a Two-Step Cluster algorithm with log-likelihood distance measure, and auto clustering using Schwarz's Bayesian Information Criterion, validated by silhouette index. In addition, a multicollinearity test was conducted to reduce redundancy in using variable sets. The results showed that, the improvement of the cluster quality based on the silhouette index value, was achievable by excluding the tree spatial distribution variable, which exhibits multicollinearity. The cropping patterns were classified into three categories, namely tree crops, mixed-tree lots, and agrisilviculture for group-1, group-2, and group-3, respectively. Group-1 consisted of stands with one or two commercial tree species, and in several cases, were intercropped. Group-2 contained uneven-aged mixed-tree stands without any crops. While Group-3 consisted of an intercropping system of uneven-aged mixed-tree stands and crops. The results suggest further analysis, in order to relate the cropping patterns with the socio-economic characteristics of the landowners, as well as the strategies for the development of a sustainable SSPF.

Temporal and Spatial Variation of Aboveground Biomass of Pinus densata and Its Drivers in Shangri-La, CHINA

Understanding the drivers of forest aboveground biomass (AGB) is essential to further understanding the forest carbon cycle. In the upper Yangtze River region, where ecosystems are incredibly fragile, the driving factors that make AGB changes differ from other regions. This study aims to investigate AGB’s spatial and temporal variation of Pinus densata in Shangri-La and decompose the direct and indirect effects of spatial attribute, climate, stand structure, and agricultural activity on AGB in Shangri-La to evaluate the degree of influence of each factor on AGB change. The continuous sample plots from National Forest Inventory (NFI) and Landsat time series were used to estimate the AGB in 1987, 1992, 1997, 2002, 2007, 2012, and 2017. The structural equation model (SEM) was used to analyze the different effects of the four factors on AGB based on five scales: entire, 1987–2002, 2007–2017, low population density, and high population density. The results are as follows: (1) The AGB of Pinus densata in Shangri-La decreased from 1987 to 2017, with the total amount falling from 9.52 million tons to 7.41 million tons, and the average AGB falling from 55.49 t/ha to 40.10 t/ha. (2) At different scales, stand structure and climate were the drivers that directly affect the AGB change. In contrast, the agricultural activity had a negative direct effect on the AGB change, and spatial attribute had a relatively small indirect effect on the AGB change. (3) Analyzing the SEM results at different scales, the change of the contribution of the agricultural activity indicates that human activity is the main negative driver of AGB change in Shangri-La, especially at the high population density region. In contrast, the change of the contribution of the stand structure and climate indicates that the loss of old trees has an important influence on the AGB change. Forest resources here and other ecologically fragile areas should be gradually restored by adhering to policies, such as strengthening forest protection, improving forest stand quality, and limiting agricultural production activities.

A study of the relationship between heights and diameters at breast height in tree stands of Scots pine in the Training and Experimental Forestry of the Leningrad region

Взаимосвязи между высотами деревьев и диаметрами на высоте груди широко применяются при определении запасов и сортиментной структуры древостоев. Для их описания применяются многочисленные математические модели. Сравнительный анализ точности шести моделей на примере древостоев сосны обыкновенной Учебно-опытного лесничества Ленинградской области показал близкую точность каждой из них. При этом для разных пробных площадей наибольшую точность показывали разные модели. Это обуславливает необходимость дальнейших исследований по данной тематике с целью выявления наиболее применимых для различных древесных пород, возрастов и условий местопроизрастаний математических моделей. В практической деятельности часто используются таблицы, составленные с учетом соотношений высот и диаметров на высоте груди в древостоях, основными из которых являются таблицы объемов стволов по разрядам высот и сортиментные таблицы. В рамках исследования было установлено, что фактические зависимости высот деревьев от диаметров на высоте груди отличаются от приведенных в таблицах, что обусловлено индивидуальными особенностями структуры и условий местопроизрастания древостоев. По этой причине разряды высот, определенные для отдельных ступеней толщины, зачастую отличаются от найденных по средним для древостоя высоте и диаметру на высоте груди. Это приводит к расхождениям в найденных с учетом данных двух подходов запасах древостоев, а также выхода и стоимости сортиментов в них. Несмотря на незначительность различий, их наличие свидетельствует о необходимости дальнейших исследований с целью повышения точности определения таксационных показателей древостоев. The relationships between heights and diameters at breast height of trees are widely used in determining of growing stock and assortment structure of stands. Numerous mathematical models are used to describe them. A comparative analysis of the accuracy of six models on the example of tree stands of Scots pine in the Training and Experimental Forestry of the Leningrad region showed the close accuracy of each of them. For different sample plots, however, the highest accuracy was showed by different models. This necessitates further research on this topic in order to identify the most applicable mathematical models for different tree species, ages and habitat conditions. In practice are often used the tables, compiled taking into account the ratios of heights and diameters at breast height in tree stands, the main of which are tables of volumes of trees by height ranks and assortment tables. Within the framework of the study, it was found that the actual relationships between tree heights and diameters at breast height differ from those given in the tables, which is due to the individual features of the stand structure and habitat conditions. For this reason, the height ranks, determined for individual diameter classes often differ from those found for the average tree stand height and diameter at breast height. This leads to discrepancies in the growing stocks of tree stands, found taking into account these two approaches, as well as the yield and cost of assortments in them. Although the differences are insignificant, they highlight the need for further research in order to improve the accuracy of determining the inventory parameters of tree stands

Betula pendula Ssp. distribution and growth in the sub-Carpathian curvature

Birch ssp. in the sub-Carpathians curvature can be found in composition with beech and other resinous species, unevenly distributed from the mountain peaks at around 1200 m down to 500-600, mainly from high hills to depressions at 600m, rarely seen on plain sites, crossing different geomorphological structures and overall accounting for 3857.1 ha. The main objective of the paper was to analyze the site and stand characteristics of Betula pendula ssp. Roth. in the subCarpathians curvature as followed: stand structure, stand types and stand site types, soils and different metrics, from growth to yields and its connectivity.The ecological adaptability to climate and soil and early fast growth, makes silver birch fulfill the overall requirements as a pioneer species, mostly naturally regenerated. Birch distribution is highly influenced by stand structure having low proportion in compositions, mean height of 15 m at age 50, and a diameter of 20m. Regarding the site, characteristics are more commonly found on fertile soils, corrugated or fragmented site type with a slope of 20-50° and it is distributed as secondary species in stands, averaging 750m in attitude, ranging from 500 to 1200m, 90% being in mixtures with other species with a mean annual increment of approximately 7 m³/year/ha regardless of stand site type. As an early successional species, it serves as a first colonizer but secondary species and quite often as an ecological instrument to improve the soil characteristics, biodiversity and prevent landslides in certain sites, lacking economic value other than fuel wood or other non-wood products.

Threshold Response to Extreme Drought Shifts Inter-Tree Growth Dominance in Pinus sylvestris

Many studies quantify short-term drought impact on tree growth relative to pre-drought growth averages. However, fewer studies examine the extent to which droughts of differing severity differentially impact tree growth or shape stand dynamics. Focusing on three droughts in high and low density stands of Pinus sylvestris in Scotland, we calculated pre-drought growth averages using climatically standardized antecedent growth years to assess tree level drought and post-drought growth performance as percentage growth change (PGC). We then used mixed-effects models to understand how droughts of differing severity impact tree growth and calculated indices of growth dominance (Gd), size inequality (Si), and size asymmetry (Sa) to detect changes in stand structure. Mixed-effects model results indicate that the magnitude and duration of the growth reduction during and following the more extreme drought was significantly larger compared to less severe droughts, for which we found limited evidence of drought impact. While no changes in Si or Sa were noted following any drought, we found evidence of a difference in Gd after the most extreme drought in both stand densities indicative of a threshold response, with smaller trees contributing proportionally more to stand growth relative to their size. Under less severe droughts, inter-tree variability may have partially buffered against stand-level growth change, however, a small increase in drought severity was associated with a significant reduction in average tree growth, an increase in the number of trees growing at >2SD below pre-drought levels and a shift in Gd toward smaller trees, indicating that a drought severity threshold in P. sylvestris may have been exceeded.