Allometric relations between biomass and diameter at breast height and height of tree in natural forests at Me Linh Station for Biodiversity, Vinh Phuc Province, Vietnam

Effects of biotic and abiotic drivers on the growth rates of individual trees in temperate natural forests

Dalbergia tonkinensis is being promoted in Vietnam for the future supply of prized wood for furniture and chemical extraction. Expansion of the plantation area requires a reliable source of quality seed. This study evaluates the field performance of progeny from mature mother trees in natural forests and urban environments. Trials were established in Tan Son and Doan Hung districts of Phu Tho province and assessed 3 years later. There were significant differences in growth and survival between provenances. The best families reached heights of >3.5 m and came from mother trees in a natural forest. The number of leaflets per leaf on mother trees was positively correlated with height (Ht) and diameter at breast height (Dbh) of the trial trees. The individual heritabilities (ĥ2) for Ht and Dbh were 0.39 and 0.49 for Tan Son, and 0.33 and 0.48 for Doan Hung, respectively. The coefficient of additive variation (CVA) of Ht and Dbh were 36% and 58% for Tan Son, and 23% and 30% for Doan Hung, respectively. Interactions between the growth traits in the two trials were strongly correlated (R2 = 0.88 for Ht, 0.90 for Dbh). These results identify D. tonkinensis gene sources with advantages for early growth performance in plantations. These superior genetics can be used for seed orchards, clonal propagation and for implementing a breeding program.

Abstract. To determine if trees in urban or ornamental plantings are more susceptible to attack and receive more damage to foliage by herbivores than trees in natural forests, we compared the amount of leaf damage caused by several guilds of insects feeding on seven species of native, broadleaf trees in two geographic locations. Total leaf damage did not differ significantly between urban or ornamental and natural forests, although trees in natural forests tended to have slightly higher levels of leaf damage. Damage caused by chewing insects was consistently higher on trees in natural forests than in urban or ornamental plantings. All other feeding guilds showed no consistent pattern in levels of damage between the two habitats. Total damage levels were highest on canopy trees and lowest on understorey trees. These results are inconsistent with the view that trees in urban or ornamental settings are more susceptible to insect attack than trees in natural forests. The lower level of foliar damage caused by chewing insects on trees in urban or ornamental plantings may arise because of low rates of dispersal by insects into urban environments, higher levels of plant resistance to insect attack in urban or ornamental plantings, or lower survival rates of herbivorous insects in urban environments.

Regression estimators for aboveground biomass and its constituent parts of trees in native southern Brazilian forests

BackgroundLarch (Larix Mill.) forests are widely distributed in the upper parts of mountainous areas in China, playing vital roles in constructing mountain landscapes and maintaining mountain environments. Despite their importance, our knowledges on the large-scale patterns of structure characteristics and the relationships between different structure variables are unclear. In this paper, we investigated 155 plots from 11 natural larch forest types across the country to explore the biogeographic patterns of the structure characteristics and the allometric relationships between different structure variables for Chinese larch forests.ResultsThe structure characteristics were significantly different among larch forest types. For different larch forest types, the power function fits the relationships between tree height and diameter at breast height (DBH), average DBH and stem density, and taper and stem density well, but with different exponents among larch forest types. The power exponents of the allometric relationships between tree height and DBH for different larch forest types varied from 0.61 to 0.93 (mean = 0.86) by standard major axis regression (SMA), and from 0.51 to 0.78 (mean = 0.56) by ordinary least square regression (OLS). The 50%, 75% and 95% quantile regression (QR) and OLS indicated that the average DBH and taper of the L. gmelinii forests, L. gmelinii var. principis-rupprechtii forests, and L. sibirica forests were significantly correlated with stem density.ConclusionsThe relationship between tree height and DBH showed a power function relationship for all larch forest types in China, but with different exponents. Overall, stem density was negatively correlated with average DBH and taper. The Sect. Larix forests exhibited stand density effect. Our findings provide an important basis for recognizing the biogeographic patterns of structure factors and for the management of larch forests in China.

There are large areas of big-leaf mahogany (Swietenia macrophylla King) afforestation and reforestation plantations for reducing carbon dioxide due to climate change in Taiwan. In Taiwan, out of the total area of mahogany plantations of approximately 2982.00 ha, 125.40 ha is in national forests and 232.00 is at the Hsin-Hua Experimental Forest Station. Biomass is a plant attribute that accumulates over time. It is an important indicator of growth and is used in analysis and management processes. Above-ground biomass is the key parameter in many allometric relationships. However, there are few studies on below-ground biomass estimations of mahogany, for it is difficult to excavate and quantify these portions. The aim of this study was to establish an allometric relationship to estimate the above-ground (stem wood, stem bark, branches, and foliage) and belowground (roots) biomass using an easily measured value, such as the diameter at breast height (DBH), diameter at the stem base (DSB) and tree height (H). Forty-six mahogany saplings (0 cm ≤ DBH ≤ 10 cm), with different ages in the second compartment of this forest station, were used to establish the allometric functions of DBH and biomass, and functions of DSB and biomass. A significance test of the correlation was used to test the relationship between DBH and biomass in different sections, including foliage, branches, stems, above-ground, below-ground, and the entire tree. The DSB was also tested. The results showed that the power regression function was superior to other functions. The correlation between DBH and biomass was higher than the correlation between DSB and biomass. The allometric functions for the entire tree biomass, above-ground biomass, and below-ground biomass were W = 175.67×DBH^2.29 (R^2 = 0.9692), Wabove = 112.21×DBH^2.34 (R^2 = 0.9621), and Wbelow = 61.65×DBH^2.19 (R^2 = 0.9610), respectively. The carbon content of each part of mahogany trees was as follows: stem wood (45.83±0.92%), roots (45.09±0.89%), foliage (44.95±1.21%), branches (43.74±1.09%), and stem bark (42.64±1.01%). Managers can estimate the biomass, carbon content ratio, and carbon storage of mahogany without destroying trees.

Amazonian tropical forests are critical to global carbon cycling and sequestration, and in direct danger from deforestation. In order to contribute to limited existing literature on the carbon sequestration potential of secondary forest ecosystems and their aboveground biomass (AGB), we established permanent 0.2-ha plots in a primary and a secondary forest near Iquitos, Loreto, Peru. We measured diameter at breast height (DBH), tree height, and wood density for trees ≥10 cm DBH and took the diameter of lianas at 30 cm shoot extension, then used published allometric equations to estimate AGB and compare it between forests. Trees within the primary forest plot had a significantly greater mean DBH and higher mean wood density, as well as a greater overall AGB than trees within the secondary forest. AGB was calculated to be 322.05 Mg/ha for the primary forest and 51.17 Mg/ha for the secondary forest. Sequestered carbon quantities were 151.36 Mg/ha and 24.05 Mg/ha, respectively. Higher estimates of stored carbon within the primary forest are attributed to old- growth trees with large DBH values and increased wood density, and discrepancies between our carbon estimates for the secondary forest and past estimates for the same site suggest the need to focus more research and attention on allometric equation use. The results of this study provide a potential incentive for carbon sequestration funding to be awarded to the primary forest property studied and establish a foundation for future estimations of the carbon storage capacities of tropical secondary forests.

The carbon density was not different between natural and planted forests, while the biomass carbon density was greater in natural forests than in planted forests. The difference is due primarily to the larger carbon density in the standing trees in natural forests compared to planted forests (at an average age of 50.6 and 15.7 years, respectively). Afforestation and reforestation programs might have noticeable effect on carbon stock. An integrated assessment of the forest carbon density in mountain regions is vital to evaluate the contribution of planted forests to carbon sequestration. We compared the carbon densities and carbon stocks between natural and planted forests in the Luliang Mountains region where large-scale afforestation and reforestation programs have been implemented. The introduced peashrubs (Caragana spp.), poplars (Populus spp.), black locust (Robinia pseudoacacia), and native Chinese pine (Pinus tabulaeformis) were the four most common species in planted forests. In contrast, the deciduous oaks (Quercus spp.), Asia white birch (Betula platyphylla), wild poplar (Populus davidiana), and Chinese pine (Pinus tabulaeformis) dominated in natural forests. Based on the forest inventory data of 3768 sample plots, we estimated the values of carbon densities and carbon stocks of natural and planted forests, and analyzed the spatial patterns of carbon densities and the effects of various factors on carbon densities using semivariogram analysis and nested analysis of variance (nested ANOVA), respectively. The carbon density was 123.7 and 119.7 Mg ha−1 for natural and planted forests respectively. Natural and planted forests accounted for 54.8% and 45.2% of the total carbon stock over the whole region, respectively. The biomass carbon density (the above- and belowground biomass plus dead wood and litter biomass carbon density) was greater in natural forests than in planted forests (22.5 versus 13.2 Mg ha−1). The higher (lower) spatial carbon density variability of natural (planted) forests was featured with a much smaller (larger) range value of 32.7 km (102.0 km) within which a strong (moderate) spatial autocorrelation could be observed. Stand age, stand density, annual mean temperature, and annual precipitation had statistically significant effects on the carbon density of all forests in the region. No significant difference was detected in the carbon densities between natural and planted forests, and planted forests have made a substantial contribution to the total carbon stock of the region due to the implementation of large-scale afforestation and reforestation programs. The spatial patterns of carbon densities were clearly different between natural and planted forests. Stand age, stand density, temperature, and precipitation were important factors influencing forest carbon density over the mountain region.

The relationship between tree height (h) and tree diameter at breast height (dbh) is an important element describing forest stands. In addition, h often is a required variable in volume and biomass models. Measurements of h are, however, more time consuming compared to those of dbh, and visual obstructions, rounded crown forms, leaning trees and terrain slopes represent additional error sources for h measurements. The aim of this study was therefore to develop h–dbh relationship models for natural tropical forest in Tanzania. Both general forest type specific models and models for tree species groups were developed. A comprehensive data set with 2 623 trees from 410 different tree species collected from a total of 1 191 plots and 38 sites covering the four main forest types of miombo woodland, acacia savanna, montane forest and lowland forests was applied. Tree species groups were constructed by using a k-means clustering procedure based on the h–dbh allometry, and a number of different non-linear model forms were tested. When considering the complexity of natural tropical forests in general and in particular variations of h–dbh relationships due to high species diversity in such forests, the model fit and performance were considered to be appropriate. Results also indicate that tree species group models perform better than forest type models. Despite the fact that the residual errors level associated with the models were relatively high, the models are still considered to be applicable for large parts of Tanzanian forests with an appropriate level of reliability.

Tropical forests are becoming increasingly alien-dominated through the establishment of timber plantations and secondary forests. Despite widespread recognition that afforestation results in increased evapotranspiration and lower catchment yields, little is known of the impacts of timber plantations on water balance relative to native forest. Native forest trees have been claimed to use water conservatively and enhance groundwater recharge relative to faster-growing alien species, and this argument should motivate native forest preservation and restoration. However, data have been available primarily for leaf-level gas exchange rather than for whole-plant and stand levels. We measured sap flow of dominant tree and tree fern species over eight weeks in native Metrosideros polymorpha forest and adjacent alien timber plantations on the island of Hawai'i and estimated total stand transpiration. Metrosideros polymorpha had the lowest values of sap flux density and whole-tree water use (200 kg m(-2) sapwood d(-1), or 8 kg/d for trees of 35 cm mean diameter at breast height, D), substantially less than timber species Eucalyptus saligna or Fraxinus uhdei (33 and 34 kg/d for trees of 73 and 30 cm mean D, respectively). At the stand level, E. saligna and F. uhdei trees had three- and ninefold higher water use, respectively, than native M. polymorpha trees. Understory Cibotium tree ferns were most abundant in M. polymorpha-dominated forest where they accounted for 70% of water use. Overall, F. uhdei plantation had the highest water use at 1.8 mm/d, more than twice that of either E. saligna plantation or M. polymorpha forest. Forest water use was influenced by species composition, stem density, tree size, sapwood allocation, and understory contributions. Transpiration varied strongly among forest types even within the same wet tropical climate, and in this case, native forest had strikingly conservative water use. Comparisons of vegetation cover in water use should provide additional resolution to ecosystem valuation and land management decisions.

Введение. В условиях изменяющегося климата всё более актуальны оценки полного углеродного пула всех компонентов лесных экосистем, в том числе массы отмерших ветвей (МОВ) растущих деревьев. В опубликованных данных о фитомассе деревьев отношение МОВ к надземной фитомассе (ОМОВ) варьирует в диапазоне от 0,3 до 29 %, однако попытки выявить факторы, объясняющие столь широкий его диапазон, довольно редки. Цель исследования. В настоящем исследовании предпринята первая попытка разработки аллометрических моделей, предназначенных для оценки МОВ и ОМОВ растущих деревьев сосны обыкновенной естественных древостоев и культур в условиях степной и лесостепной зон. Объекты и методы. Объектом исследования послужили чистые сосняки естественного и искусственного происхождения островных боров в степной зоне Тургайского прогиба. Для сравнения использованы опубликованные данные для естественных сосняков Красноярско-Канской лесостепи и выполнена их сравнительная оценка по МОВ и ОМОВ. Всего в анализе использовано 595 модельных деревьев, взятых на 48 пробных площадях. Результаты. Анализ парных связей МОВ с дендрометрическими характеристиками деревьев показал, что диаметр ствола объясняет от 87 до 92 % и высота дерева от 81 до 88 % изменчивости МОВ. При увеличении диаметра ствола с 6 до 26 см ОМОВ в Тургайской степи в культурах повышается с 6 до 13 %, а в естественных сосняках остаётся стабильной на уровне 4 %. Сравнительный анализ МОВ деревьев в культурах и естественных сосняках, выполненный по двухфакторной модели зависимости от диаметра ствола и высоты дерева, показал, что МОВ в культурах по сравнению с естественными древостоями выше в 1,8 раза. Сравнительный анализ МОВ деревьев в естественных сосняках Тургайской степи и Красноярско-Канской лесостепи показал, что их различие небольшое, и в среднем при увеличении диаметра ствола от 6 до 26 см МОВ изменяется с 0,3 до 9 кг, а ОМОВ остаётся стабильной на уровне 4 %. При увеличении возраста при неизменном диаметре ствола ОМОВ в естественных сосняках двух регионов снижается с 10–19 до 2–4 %. Вывод. При расчётах углеродных пулов надземной фитомассы необходимо вносить поправки в оценку пула в культурах сосны степной зоны в виде 6–13 %-ного и в естественных сосняках cтепной и лесостепной зон в виде 4 %-ного повышения за счёт МОВ. Introduction. In a changing climate, estimates of the total carbon pool of all components of forest ecosystems, including the mass of dead branches (DBM) of standing trees, are increasingly relevant. According to published data on the tree phytomass, the ratio of DBM to the aboveground phytomass, or relative DBM (RDBM), ranges from 0.3 to 29 %. However, attempts to identify the factors explaining such a wide range have been quite rare. The aim of the study. In this research, the first attempt was made to develop allometric models for estimating DBM and RDBM of Pinus sylvestris L. trees growing in the natural forest stands and plantations of the steppe and forest-steppe zones. Objects and methods. The object of the study was pure island pine forests of natural and artificial origin located in the steppe area of the Turgay Depression. For comparative purposes, published data on natural Pinus sylvestris L. forests of the Krasnoyarsk and Kansk forest steppe were utilized; their comparative evaluation in regard to DBM and RDBM was carried out. In total, 595 model trees taken from 48 sample plots were used for the analysis. Results. The analysis of paired associations of DBM with dendrometric tree characteristics showed that the trunk diameter at breast height (DBH) accounts for 87-92 % of DBM variability, and the tree height accounts for 81- 88 % of it. With an increase in DBH from 6 to 26 cm, RDBM in the Turgay steppe plantations rises from 6 to 13 %, while in natural pines forests it remains stable at 4 %. A comparative analysis of DBM of trees in plantations and natural forest stands, which was performed using a two-factor model depending on DBH and the tree height, showed that DBM in plantations was 1.8 times higher than that in natural stands. A comparative analysis of DBM of trees in the natural pine forests of the Turgay steppe and the Krasnoyarsk and Kansk forest-steppe revealed little difference; on average, with an increase in DBH from 6 to 26 cm, DBM changes from 0.3 to 9 kg, while RDBM remains stable at 4 %. With increasing age and constant DBH, RDBM in the natural pine forests of the two regions decreases from 10-19 % to 2-4 %. Conclusion. When calculating the carbon pools of the aboveground phytomass, it is necessary to make a correction to the pool estimate as a 6-13% increase for the steppe zone pine plantations, and as an increase of 4 % for the natural pine forests of the steppe and forest-steppe zones.

天然次生林蒙古栎种群空间格局

Allometric relationships for below- and aboveground biomass of young Scots pines

Many leaf traits strongly vary with tree size and environmental factors, but the importance of these factors to intraspecific variations of leaf traits in forest trees has rarely been simultaneously evaluated. We measured needle longevity and specific leaf area (SLA) and nitrogen (N) content of every needle age (0‐ to 4‐year old) for 65 individuals with 0.3–100 cm diameter at breast height (DBH) for an evergreen coniferous species, Pinus koraiensis Sieb. et Zucc., in Northeast China. We simultaneously evaluated the effects of tree size (DBH or tree height) and environment factors (light intensity, soil N content and water availability) on the needle longevity, SLA, foliage N content as well as the slopes of regressions of SLA and foliage N content against needle age. All of the studied leaf traits and slopes of regressions of SLA and foliage N content against needle age were significantly related to tree size. Tree height had a greater impact on SLA and area‐based leaf N content (Narea), whereas DBH was more important for needle longevity and mass‐based leaf N content (Nmass). The environment variables, light intensity, soil N content and water availability, were rather minor factors for trait variations compared with tree size. Significant influence of light intensity was found only on needle longevity, and soil N and water availability had no effects on the leaf traits. Our study clearly showed that tree size is an important driver of intraspecific variations in the key leaf traits of P. koraiensis in a natural forest. We also emphasize the importance of DBH or tree height varies depending on leaf traits, suggesting various mechanisms of size effects on the intraspecific variations in leaf traits. We suggest that ecological significance of leaf trait variations needs reconsideration incorporating tree size effect. A free Plain Language Summary can be found within the Supporting Information of this article.

Forest ecosystems fulfil crucial roles in mediating greenhouse gases and in harbouring biodiversity and providing products to humankind, meanwhile they are subjected to challenges from human activities and climate change. To test how prescribed burning and harvest compaction would influence the carbon (C) and nitrogen (N) cycles in forest ecosystems in the long term, we conducted a series of experiments in a natural forest and a hoop pine (Araucaria cunninghamii) plantation in subtropical Australia. Those experiments included collecting litter and soil samples from Toohey Forest to examine role of regular patch mosaic prescribed burning in regulating soil C and N pools. In situ incubations in Toohey Forest were used to assess the soil N transformations with time after prescribed burning. 15N natural abundance ([delta-N-15]) of inorganic N pools was used to quantify the responses of soil N transformation processes to elevated soil moisture which was used to mimic heavy rainfall. Collecting soil and foliage samples, measuring tree diameter at breast height over bark (DBHoB) and height in a 17-year-old machinery compaction trail site in a hoop pine plantation, Yarraman State Forest, was used to investigate the long-term impacts of harvesting compaction on soil C and N pools, and on forest productivity. [...]