Red Birch Research Articles

A SET OF TOPONYMS DEFINING THE FEATURES OF THE SOIL AND VEGETATION COVER OF THE SHET DISTRICT

The article considers a set of toponyms that determine the soil and vegetation cover of the Shet district of the Karaganda region. The patterns of distribution and the degree of manifestation of the association of phytonyms that characterize the landscape features of the territory by natural zones are determined. During the analysis of phytonyms, the names of relic juniper, pine, red birch, black alder, ash and ancient sites of these trees were identified, and the prerequisites for their restoration were created.

Characterization of the complete chloroplast genome of Betula pendula purple rain (betulaceae)

Betula pendula purple rain is a variety of Betula pendula that is native to Europe and has important ornamental and economic value. In this study, we sequenced the complete chloroplast genome of B. pendula purple rain. This genome had a typical quadripartite structure with 160,552 bases, including a large single copy (LSC) region of 89,433 bases, a small single copy (SCC) region of 19,007 bases and two inverted repeat (IR) regions of 26,056 bases. The GC content of the chloroplast genome was 36% and contained 124 genes, including 79 protein-coding genes, 8 rRNA genes and 37 tRNA genes. The maximum likelihood phylogenetic analysis of reported chloroplast genomes showed that B. pendula purple rain was most closely related to Betula occidentalis and Betula platyphylla.

STUDY ON THE DECAY EXTENT OF WOODEN COMPONENTS OF DANXIA TEMPLE ANCIENT BUILDING BY POLARIZED LIGHT, FLUORESCENCE AND X-RAY DIFFRACTION METHODS

In the present study, the decay extent of wooden components from the Halls of Pilu and Tianran ancestor of Danxia Temple ancient buildings was observed by polarized light, fluorescence, and XRD methods. The findings of the investigation can be summarized as follows. Sample No. 1 was identified as red birch wood (Betula albo-sinensis) and sample No. 2 was identified as maple wood (Pterocarya stenoptera). The brightness of crystalline cellulose birefringence in the cell walls of vessels, wood rays and wood fibres, both in decayed red birch wooden components (DRBWC) and in decayed maple wooden components (DMWC), was not obvious, indicating that the cellulose was seriously consumed by fungi. However, the brightness of green fluorescence in the cell walls of both DRBWC and DMWC was very evident, indicating that the lignin was mainly retained or was not consumed by fungi. XRD analysis indicated that wood decay fungi did not change the structure and crystal layer distance of the crystallization zone, but the diffraction intensity decreased to a certain extent. The crystallinity of cellulose was reduced by 11.16%, from 43.29% to 38.46%, in DRBWC and by 52.16%, from 40.68% to 19.46%, in DMWC, demonstrating a reduction in crystalline cellulose. The degradation of cellulose in wooden components will eventually lead to a reduction in their load-bearing capacity. According to the tendency of brown rot fungi of consuming mostly cellulose and hemicelluloses while avoiding lignin, we concluded that both DRBWC and DMWC were seriously degraded by brown rot fungi, in addition to the attack of termites. The low resistance of the two wooden components to fungal decay and termites is the main cause of their deterioration. The results on the extent of decay will provide scientific data for the future conservation and restoration of the Danxia Temple relics.

CEDAR WAXWINGS (BOMBYCILLA CEDRORUM) FEEDING ON BIRCH SAP AT RED-NAPED SAPSUCKER (SPHYRAPICUS NUCHALIS) SAP WELLS

In late June 2020 in western Montana we observed up to 10 Cedar Waxwings (Bombycilla cedrorum) feeding on tree sap at Red-naped Sapsucker (Sphyrapicus nuchalis) sap wells excavated on 2 limbs of a Water Birch (Betula occidentalis). These observations constitute (a) the 1st report of waxwings feeding at sap wells created by sapsuckers of any species; (b) the 1st report of waxwings feeding on tree sap in early summer; and (c) the 1st report of the consumption of birch sap by this waxwing species. The Cedar Waxwings may have sought tree sap because of the limited availability of early-summer sugary fruits at the time of our observations in combination with the presence of new clusters of sap wells created by at least 1 pair of sapsuckers near where the waxwings were beginning to breed. The prevalent sugars in birch sap (glucose, fructose) are also those most efficiently assimilated by Cedar Waxwings and may have contributed in attracting the waxwings to the sapsucker wells.

Optimization theory explains nighttime stomatal responses.

Nocturnal transpiration is widely observed across species and biomes, and may significantly impact global water, carbon, and energy budgets. However, it remains elusive why plants lose water at night and how to model it at large scales. We hypothesized that plants optimize nighttime leaf diffusive conductance (gwn ) to balance potential daytime photosynthetic benefits and nocturnal transpiration benefits. We quantified nighttime benefits from respiratory reductions due to evaporative leaf cooling. We described nighttime costs in terms of a reduced carbon gain during the day because of water use at night. We measured nighttime stomatal responses and tested our model with water birch (Betula occidentalis) saplings grown in a glasshouse. The gwn of water birch decreased with drier soil, higher atmospheric CO2 , wetter air, lower leaf temperature, and lower leaf respiration rate. Our model predicted all these responses correctly, except for the response of gwn to air humidity. Our results also suggested that the slow decrease in gwn after sunset could be associated with decreasing leaf respiration. The optimality-based nocturnal transpiration model smoothly integrates with daytime stomatal optimization approaches, and thus has the potential to quantitatively predict nocturnal transpiration across space and time.

Anamorphic Site Index Curves for Central Appalachian Red Spruce in West Virginia, USA

Traditional site index curves are frequently produced for shade-intolerant species but are scarce for shade-tolerant species. Red spruce (Picea rubens Sarg.) can be found in three distinct geographic regions (northern, central, and southern) within the Appalachian Mountains. The one commonly used set of red spruce site index curves is over ninety years old. A definite need exists for a modern, regionally applicable set of site index curves. This research sampled 83 plots randomly located in the central Appalachians of West Virginia. Three sets of anamorphic site index curves were created after careful examination of height models built using Chapman-Richards and Meyer functions. One set of curves was constructed with traditional age height pairs. The second utilized a suppression-corrected age and height pair. The third set examined diameter at breast height (DBH) and height pairs. Fit statistics indicated better performance for the suppression-corrected age–height pair site index and the DBH–height pair site index versus the traditional age–height pair models. Site index conversion equations were also investigated for the red spruce age-corrected site index. Linear regression was used to determine significant geographic and climate variables and the utility of including site index values for red maple (Acer rubrum L.) and yellow birch (Betula alleghaniensis Britton) in the model to predict red spruce site index. Significant models were found for varying combinations of species site index, climate, and geographic variables with R2adj in the range of 0.139–0.455. These new site index curves and conversion equations should provide utility for site productivity estimation and growth and yield modeling while aiding in restoration efforts for this important central Appalachian species.

Using LiDAR to assess transitions in riparian vegetation structure along a rural‐to‐urban land use gradient in western North America

AbstractRiparian forests are essential for stream ecological processes in arid and semiarid regions, however, they are often highly altered by the rapid expansion of urban areas. To maintain riparian ecosystems services, it is important to better understand the effects of urbanization on riparian forests. We quantified the three‐dimensional (3D) structure and woody species composition of a riparian corridor in Utah, USA, to evaluate patterns of vegetation along stream reaches that flow through distinct hydrologic domains (with gaining and losing reaches) and through a rapid rural‐to‐urban gradient. By using LiDAR imaging and field observations, we explore the extent to which the riparian vegetation structure follows patterns of topography linked to energy and water subsidies and patterns of human influence along the stream. Whereas natural reaches of Red Butte Creek were characterized by native vegetation and typical riparian species (e.g., Betula occidentalis), urbanized reaches had higher numbers of introduced plants (e.g., Acer platanoides) and more upland species (e.g., Quercus gambelii). Urban reaches were also characterized by exceptionally high trees (>18 m) in older residential neighbourhoods. In the natural area, canopy height was negatively correlated with height above the river (HAR). Additionally, we found higher cover and taller canopies on north‐facing aspects. These results show that LiDAR data, in combination with ground observations, can reveal strong influences of hydrology as well as land use in different canopy layers of riparian forests. We suggest that the decision making of individual landowners shapes vegetation beyond natural hydrological patterns, with implications for riparian forest management and restoration.

Complete chloroplast genome sequence of Betula microphylla (Betulaceae)

Betula microphylla (Betulaceae) is a species widely distributed in Xinjiang China and in Mongolia and Siberia of Russia. In this study, we described the complete chloroplast genome of B. microphylla based on Illumina paired-end sequencing. The chloroplast genome of B. microphylla is 160,489 bp long, including two inverted repeats (IRs, 26,070 bp), separated by a large single-copy region (LSC, 89,306 bp), and a small single-copy region (SSC, 19,045 bp). The overall GC content of the whole genome is 36.1%, and the corresponding values of the LSC, SSC, and IR regions are 33.7%, 29.7%, and 42.5%. The phylogenetic analysis indicated that B. microphylla is closely related to Betula occidentalis.

The stomatal response to rising CO2 concentration and drought is predicted by a hydraulic trait-based optimization model.

Modeling stomatal control is critical for predicting forest responses to the changing environment and hence the global water and carbon cycles. A trait-based stomatal control model that optimizes carbon gain while avoiding hydraulic risk has been shown to perform well in response to drought. However, the model's performance against changes in atmospheric CO2, which is rising rapidly due to human emissions, has yet to be evaluated. The present study tested the gain-risk model's ability to predict the stomatal response to CO2 concentration with potted water birch (Betula occidentalis Hook.) saplings in a growth chamber. The model's performance in predicting stomatal response to changes in atmospheric relative humidity and soil moisture was also assessed. The gain-risk model predicted the photosynthetic assimilation, transpiration rate and leaf xylem pressure under different CO2 concentrations, having a mean absolute percentage error (MAPE) of 25%. The model also predicted the responses to relative humidity and soil drought with a MAPE of 21.9% and 41.9%, respectively. Overall, the gain-risk model had an MAPE of 26.8% compared with the 37.5% MAPE obtained by a standard empirical model of stomatal conductance. Importantly, unlike empirical models, the optimization model relies on measurable physiological traits as inputs and performs well in predicting responses to novel environmental conditions without empirical corrections. Incorporating the optimization model in larger scale models has the potential for improving the simulation of water and carbon cycles.

Population structure of Betula albosinensis and Betula platyphylla: evidence for hybridization and a cryptic lineage.

Background and AimsDifferences in local abundance and ploidy level are predicted to impact the direction of introgression between species. Here, we tested these hypotheses on populations of Betula albosinensis (red birch) and Betula platyphylla (white birch) which were thought to differ in ploidy level, the former being tetraploid and the latter diploid.MethodsWe sampled 391 birch individuals from nine localities in China, and classified them into species based on leaf morphology. Twelve nuclear microsatellite markers were genotyped in each sample, and analysed using principal coordinates analysis and STRUCTURE software. We compared the effects of two different methods of scoring polyploid genotypes on population genetic analyses. We analysed the effect of ploidy, local species abundance and latitude on levels of introgression between the species.Key ResultsLeaf morphology divided our samples into red and white birch, but genetic analyses unexpectedly revealed two groups within red birch, one of which was tetraploid, as expected, but the other of which appeared to have diploid microsatellite genotypes. Five individuals were identified as early-generation hybrids or backcrosses between white birch and red birch and five were identified between red birch and ‘diploid’ red birch. Cline analysis showed that levels of admixture were not significantly correlated with latitude. Estimated genetic differentiation among species was not significantly different between determined tetraploid and undetermined tetraploid genotypes.ConclusionsLimited hybridization and gene flow have occurred between red birch and white birch. Relative species abundance and ploidy level do not impact the direction of introgression between them, as genetic admixture is roughly symmetrical. We unexpectedly found populations of apparently diploid red birch and this taxon may be a progenitor of allotetraploid red birch populations. Incomplete lineage sorting may explain patterns of genetic admixture between apparently diploid and allotetraploid red birch.

Soil warming affects sap flow responses to meteorological conditions for Betula albosinensis at a subalpine wetland in the edge of northeast Qinghai–Tibet Plateau

AbstractTranspiration in cold‐limited areas is restricted by low soil temperature. However, little is known about the influence of soil warming on tree transpiration under a water logged and cold soil conditions. We aimed to test the hypothesis that an increase in soil temperature in the absence of water stress will lead to increased sap flow of red birch (Betula albosinensis) in a subalpine wetland. Sap flow and relevant environmental data were measured for B. albosinensis in a subalpine wetland in the edge of northeast Qinghai–Tibet Plateau from 2013 to 2016. The cooling and controlling experiments were also conducted in the lab from June to July in 2017. The results showed that meteorological parameters, as well as soil temperature, are important limiting factors for tree transpiration. It was governed by meteorological factors throughout the growing season, whereas we only found a significant increase of sap flow upon soil warming in the mid‐growing season, which may be attributed to warm‐induced hydraulic conductivity. In the early growing season, no warming effect was observed on sap flow. We then concluded that whole‐tree water use may increase with increasing soil temperature and similar precipitation and thus alter the local water balance. These results are essential to understand the response of hydrological processes to future climate warming.

Distinctions in heterotrophic and autotrophic-based metabolism as recorded in the hydrogen and carbon isotope ratios of normal alkanes.

The hydrogen isotope values of n-alkanes (δ2Hn-alkane) reflect a plant's water source and water relations, while the carbon isotope values (δ13Cn-alkane) relate to a plant's carbon metabolism and response to environmental conditions. However, the isotopic dynamics of the transition from heterotrophic to autotrophic metabolism during foliar development on δ2Hn-alkane and δ13Cn-alkane remain unclear. Here, we monitored δ2Hn-alkane and δ13Cn-alkane across a growing season from Betula occidentalis, Populus angustifolia, and Acer negundo. In addition, we compiled δ2H values of atmospheric vapor, leaf water, xylem water, and stream water as well as δ13C values of bulk leaf tissue (δ13Cbulk). We found δ2Hn-alkane and δ13Cn-alkane varied with leaf development and indicated that the majority of wax development occurred during the initial growing season. The patterns in δ2Hn-alkane were broadly consistent between species and with previous studies; however, each species had a unique final δ2Hn-alkane value. The δ13Cbulk for all species demonstrated a characteristic 13C-enrichment during the initial growing season, followed by 13C-depletion, while δ13Cn-alkane did not exhibit a consistent trend between the species. These δ13C data suggested a decoupling of the isotopic inputs between n-alkanes and photosynthetic leaf tissue. When coupled with δ2Hn-alkane, these data suggested that the precursor compounds utilized in initial production of n-alkanes might be variable and possibly indicated that the stored precursors used for initial leaf tissue and wax production originated from different sources. Nonetheless, these data indicated that the isotopic signatures of n-alkanes relate to a mixture of precursors, but only during a distinct period of leaf ontogeny.

Convergence in leaf size versus twig leaf area scaling: do plants optimize leaf area partitioning?

Corner's rule states that thicker twigs bear larger leaves. The exact nature of this relationship and why it should occur has been the subject of numerous studies. It is obvious that thicker twigs should support greater total leaf area ([Formula: see text]) for hydraulical and mechanical reasons. But it is not obvious why mean leaf size ([Formula: see text]) should scale positively with [Formula: see text] We asked what this scaling relationship is within species and how variable it is across species. We then developed a model to explain why these relationships exist. To minimize potential sources of variability, we compared twig properties from six co-occurring and functionally similar species: Acer grandidentatum, Amelanchier alnifolia, Betula occidentalis, Cornus sericea, Populus fremontii and Symphoricarpos oreophilus We modelled the economics of leaf display, weighing the benefit from light absorption against the cost of leaf tissue, to predict the optimal [Formula: see text] combinations under different canopy openings. We observed a common [Formula: see text] by [Formula: see text] exponent of 0.6, meaning that [Formula: see text]and leaf number on twigs increased in a specific coordination. Common scaling exponents were not supported for relationships between any other measured twig properties. The model consistently predicted positive [Formula: see text] by [Formula: see text] scaling when twigs optimally filled canopy openings. The observed 0·6 exponent was predicted when self-shading decreased with larger canopy opening. Our results suggest Corner's rule may be better understood when recast as positive [Formula: see text] by [Formula: see text] scaling. Our model provides a tentative explanation of observed [Formula: see text] by [Formula: see text] scaling and suggests different scaling may exist in different environments.

The losses of condensed tannins in six foliar litters vary with gap position and season in an alpine forest

Condensed tannins (CTs) have been considered to be intrinsic variables that determine litter decomposition. Forest gaps and the surrounding crown canopies may locally influence the microenvironmental factors, thus affecting the losses of CTs from litter. However, little information is available about the dynamics of CTs loss in forest gaps. In this study, litterbags containing foliar litter of Minjiang fir (Abies faxoniana), red birch (Betula albosinensis), Masters larch (Larix mastersiana), cypress (Sabina saltuaria), Kangding willow (Salix paraplesia), and Lapland azalea (Rhododendron lapponicum), were placed on the forest floor at differet positions from the gap center to the closed canopy in the alpine Minjiang fir forest located in the upper reaches of the Yangtze River and the eastern Tibetan Plateau (China). The samples were retrieved during the periods of snow formation, snow cover, snow melt and in the growing season, and the CTs content was measured at each time point. During the first year, all six types of foliar litter experienced high losses of CTs with values ranging from 70.18% to 96.67%. Forest gaps accelerated litter CTs losses in the winter but inhibited CTs losses in the growing season, which demonstrated significant seasonal differences. Additionally, the litter of conifers exhibited greater CTs losses in the winter, especially during the snow formation period, whereas the litter of broadleaved trees showed greater CTs losses during the growing season. These results indicate that the predicted reductions in snow depth resulting from future winter warming and the loss of forest gaps due to forest regeneration will inhibit the decomposition of CTs in the litter of alpine forest ecosystems, which will slow soil carbon sequestration from foliar litter in cold biomes.

Seems like I Hardly See Them Around Anymore: Historical Geographies of Riparian Change along the Wind River

Riparian areas—and the cottonwoods, water birch, bull berry, and currants that flourish within them—hold special significance for Tribes of the Intermountain American West. These species have served ceremonial and practical purposes for generations. Yet cottonwoods have experienced well-documented declines over the past several decades, and serve as indicators of overall riparian change. Research generally attributes this shift to the development of water control infrastructure, altered flood regimes, invasive species, and grazing, and rightfully so. Less attention has been paid to the cultural and historical geographies underlying these vectors of change. This research focuses on the Wind River as a case study to examine the cultural and historical factors related to riparian change. Using remote sensing, interviews and document analysis, we specifically examine boundaries between tribal/non-tribal lands along the Wind River and (1) heterogeneous patterns of riparian change, (2) significant differences in settlement patterns and the development of water infrastructure, and (3) distinct differences in water governance and its power relationships. We conclude that riparian change is heterogeneous; differs temporally, spatially, and between cultural boundaries; and relates to a socio-ecological interplay of values, practices, and policies that underlie water control, flood regime change, and proliferation of invasive species. Ultimately this research suggests that examinations of riparian change would benefit from additional in depth analyses of cultural and historical geographies, and their temporal and spatial relationships. Furthermore, tribal sovereignty over land and water may have significant impacts on overall landscape mosaics, particularly regarding the maintenance of species that support traditional lifeways.

Allergens might trigger migraine attacks.

Migraine is a common primary headache disorder. The mechanisms underlying the onset of a migraine attack are not completely understood. Environmental changes and a number of other factors could induce migraine attacks. The aim of this study was to investigate the relationship between the frequency of migraine attacks and allergens. Migraine patients without aura, and healthy individuals similar in age and gender without a history of headache and allergy were prospectively included in the study. The duration of migraine, the frequency of migraine attacks, the medication history, and the symptoms during attacks were questioned. Migraine disability assessment score (MIDAS) and visual analog scale (VAS) scores were obtained. Allergen extracts including dust, fungi, insect, animal epithelium, pollens, and food allergens were applied for allergy tests. 49 migraine patients and 49 healthy individuals were enrolled in the study. There was no significant difference in terms of age and gender. The median migraine disease duration, the number of attacks in a month, and the duration of attacks were, respectively, 5.5years (1-44), 4 (1-10) day/month, and 24 (4-72)h. The mean MIDAS grade was 2.45±0.14 (1-4), and mean VAS score was 7.89±0.27 (4-10). The positivity of allergy tests was 55.1% (27/49) in the migraine group and 32.7% (16/49) in the control group (p<0.05). The allergy tests were positive for house dust, red birch, hazel tree, olive tree, nettle, and wheat. The frequency of migraine attacks was higher in allergy-test-positive patients than in negative ones in the migraine group (p=0.001). The migraine patients who had frequent attacks should be examined for allergies.

Effects of Forest Gaps on Litter Lignin and Cellulose Dynamics Vary Seasonally in an Alpine Forest

To understand how forest gaps and the associated canopy control litter lignin and cellulose dynamics by redistributing the winter snow coverage and hydrothermal conditions in the growing season, a field litterbag trial was conducted in the alpine Minjiang fir (Abies faxoniana Rehder and E.H. Wilson) forest in a transitional area located in the upper reaches of the Yangtze River and the eastern Tibetan Plateau. Over the first year of litter decomposition, the litter exhibited absolute cellulose loss and absolute lignin accumulation except for the red birch litter. The changes in litter cellulose and lignin were significantly affected by the interactions among gap position, period and species. Litter cellulose exhibited a greater loss in the winter with the highest daily loss rate observed during the snow cover period. Both cellulose and lignin exhibited greater changes under the deep snow cover at the gap center in the winter, but the opposite pattern occurred under the closed canopy in the growing season. The results suggest that decreased snowpack seasonality due to winter warming may limit litter cellulose and lignin degradation in alpine forest ecosystems, which could further inhibit litter decomposition. As a result, the ongoing winter warming and gap vanishing would slow soil carbon sequestration from foliar litter in cold biomes.

高山森林林窗对凋落叶分解的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 高山森林林窗对凋落叶分解的影响 DOI: 10.5846/stxb201410192049 作者: 作者单位: 四川农业大学生态林业研究所,四川农业大学生态林业研究所,四川农业大学生态林业研究所,四川农业大学,四川农业大学生态林业研究所,四川农业大学生态林业研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31170423,31270498);国家"十二五"科技支撑计划(2011BAC09B05);四川省杰出青年学术与技术带头人培育项目(2012JQ0008,2012JQ0059);中国博士后科学基金(2012T50782);四川省教育厅青年基金(2013SZB0553,13TD0015);生态安全与保护四川省重点实验室开放基金项目(ESP201309,ESP1404) Effects of gap sizes on foliar litter decomposition in alpine forests Author: Affiliation: Key Laboratory of Ecological Forestry Engineering,Institute of Ecology Forestry,Sichuan Agricultural University,Wenjiang,Key Laboratory of Ecological Forestry Engineering,Institute of Ecology Forestry,Sichuan Agricultural University,Wenjiang,Key Laboratory of Ecological Forestry Engineering,Institute of Ecology Forestry,Sichuan Agricultural University,Wenjiang,Key Laboratory of Ecological Forestry Engineering,Institute of Ecology Forestry,Sichuan Agricultural University,Wenjiang,Key Laboratory of Ecological Forestry Engineering,Institute of Ecology Forestry,Sichuan Agricultural University,Wenjiang,Key Laboratory of Ecological Forestry Engineering,Institute of Ecology Forestry,Sichuan Agricultural University,Wenjiang Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:林窗对降水和光照等环境条件的再分配以及分解者群落的影响可能深刻作用于森林凋落物分解过程,但有关高山森林林窗大小对凋落物分解的影响尚无研究报道。采用凋落物分解袋法,研究了川西高山森林不同大小林窗对非生长季节和生长季节红桦(Betula albo-sinensis)和岷江冷杉(Abies faxoniana)凋落叶质量损失的影响。结果显示,经过1a的分解,不同生境下红桦和岷江冷杉凋落叶分别分解了27.25%-30.12%和27.04%-27.96%,其中非生长季节占53.83%-60.18%和50.23%-59.09%。林窗对红桦和岷江冷杉凋落叶质量损失的影响因物种不同而呈现季节差异。总体上,林窗加快了岷江冷杉凋落叶的分解而延缓了红桦凋落叶的分解。与郁闭林下相比,林窗显著增加了2种凋落叶非生长季节的质量损失速率,显著降低了生长季节2种凋落叶的质量损失速率;2种凋落叶质量损失速率在非生长季节随林窗面积增大而加快,在生长季节随林窗面积增大而减慢。林窗显著影响了初冻期、深冻期和融化期岷江冷杉凋落叶的质量损失率,但对红桦凋落叶质量损失率影响不显著。可见,高山森林凋落物分解过程受到林窗的显著影响,并且阔叶和针叶凋落叶在非生长季节和生长季节对林窗的响应具有明显差异。 Abstract:Forest gaps are one of the most normal interferences in primary forest ecosystems, and they play an important role in not only aboveground processes but also belowground processes. However, many studies have paid more attention to the effects of forest gaps on aboveground processes. Increasing evidence has demonstrated that forest gaps have a strong effect on mass loss and carbon and nutrient release in litter by redistributing precipitation, light, and other environmental factors. At high latitudes and altitudes, litter decomposition due to forest gaps may be more complex because of seasonal snow cover and freeze-thaw cycles. Theoretically, interception of rainfall and snowfall in the winter by the canopy and canopy shading may cause the hydrothermal dynamics on the forest floor to vary with respect to gap sizes and critical periods. Currently, little information is available on the effects of gap sizes on litter decomposition at different critical periods. In order to understand the effects of forest gaps on litter decomposition in forest ecosystems at high altitudes, litterbags with red birch (Betula albosinensis) and Minjiang fir (Abies faxoniana) foliar litter were incubated on the forest floor in small, medium, and large gaps and the adjacent closed canopy from November 21, 2011 to October 29, 2012. Then, the litterbags were sampled at the periods of onset of soil freezing (OF), soil deep-freezing (DF), soil thawing (TP), early growth (EP), mid-growth (MP), and late growth (LP), and the mass loss was calculated. After a year of litter decomposition, red birch and Minjiang foliar litter lost 27.25-30.12% and 27.04-27.96% mass, respectively. The mass loss of red birch and Minjiang fir foliar litter in the non-growing season accounted for 53.8-60.18% and 50.23-59.09% of the total mass loss, respectively. Gap sizes have strong effects on the mass loss of Minjiang fir and red birch foliar litter, depending on tree species and sampling periods. Forest gaps accelerated the litter decomposition of Minjiang fir, but slowed down the litter decomposition of red birch. Regardless of tree species, forest gaps significantly accelerated the rates of mass loss of foliar litter in the non-growing season (P < 0.05), but significantly lowered them in the growing season (P < 0.05). The rates of mass loss of foliar litter increased with gap sizes in the non-growing season, but decreased with gap sizes in the growing season. Moreover, the rates of mass loss of Minjiang fir foliar litter in the periods of OF, DF, and TP increased significantly with gap sizes (P < 0.05), but the effects on red birch foliar litter were not significant (P > 0.05). In addition, the contribution of litter mass loss at different critical periods to a year of mass loss was in the order of DF > MP > OF > EP > LP > TP. Mass loss of red birch foliar litter in the non-growing season accounted for 60.18%, 54.46%, 55.34%, and 53.83% of the one-year mass loss in large gaps, middle gaps, small gaps, and closed canopy, respectively; similarly, the contributions of mass loss of Minjiang fir foliar litter to the one-year mass loss in the non-growing season were 59.09%, 54.37%, 52.22%, and 50.23%, respectively. These results suggest that forest gaps accelerated the mass loss of foliar litter in the snow-cover season, but slowed down the mass loss in the growing season. The responses of litter decomposition to gap sizes in the snow-cover season were different from those in the growing season, implying that gap sizes could have strong effects on litter decomposition at different critical periods in the coniferous forest ecosystem of alpine regions. 参考文献 相似文献 引证文献

亚高山森林林窗大小对凋落叶木质素降解的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 亚高山森林林窗大小对凋落叶木质素降解的影响 DOI: 10.5846/stxb201503240562 作者: 作者单位: 绵阳师范学院,四川农业大学 生态林业研究所/林业生态工程省级重点实验室,四川农业大学 生态林业研究所/林业生态工程省级重点实验室,四川农业大学 生态林业研究所/林业生态工程省级重点实验室,四川农业大学 生态林业研究所/林业生态工程省级重点实验室,四川农业大学 生态林业研究所/林业生态工程省级重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31170423，31270498）；国家“十二五”科技支撑计划（2011BAC09B05）；四川省杰出青年学术与技术带头人培育项目（2012JQ0008，2012JQ0059）；中国博士后科学基金（2012T50782）；四川省教育厅青年基金（2013SZB0553，13ZB0121，13TD0015）；绵阳师范学院校级项目（QD2015A004，2015A01）；生态安全与保护四川省重点实验室开放基金项目（ESP201309，ESP1404） Effects of gap sizes on the lignin degradation of foliar litter in a subalpine forest Author: Affiliation: Ecological Security and Protection Key Laboratory of Sichuan Province,,Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University,Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University,Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University,Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:木质素降解是认识高寒森林凋落物分解过程的关键环节，可能受到林窗大小及其在不同季节水热环境的影响。采用分解袋法，研究了川西亚高山森林不同面积大小林窗下红桦（Betula albo-sinensis）和岷江冷杉（Abies faxoniana）凋落叶在初冻期、深冻期、融化期、生长季节初期、生长季节中期和生长季节后期的木质素分解动态特征。研究结果表明，采样时间和林窗面积大小对两种凋落叶的木质素降解均有显著影响。经历1a分解，红桦凋落叶的木质素降解了21.53%-27.65%，而岷江冷杉凋落叶的木质素富集了7.95%-19.40%。较大林窗促进了冬季岷江冷杉凋落叶和生长季节红桦凋落叶木质素的降解，抑制了冬季红桦凋落叶木质素的降解；而生长季节岷江冷杉凋落叶木质素富集速率则为林下 > 大林窗 > 中林窗 > 小林窗。逐步回归分析表明，凋落叶木质素的降解过程在冬季主要受到负积温和土壤冻融循环次数的影响（木质素结构的物理破碎），而在生长季节则主要受到平均温度和正积温的影响（木质素的生物降解）。可见，川西亚高山森林木质素降解受林窗格局变化的显著影响，且林窗大小对凋落叶木质素降解的影响与物种和分解时期有关。 Abstract:Lignin, a major component of foliar litter, plays a crucial role in litter decomposition process in forest ecosystems. However, forest gap may affect lignin degradation of foliar litter in subalpine forests, since gaps with different sizes not only regulate snow cover and its associated freeze-thaw events in winter, but also affect temperature and moisture conditions during the following growing season; however, little information about the gap size-effect is currently available. To test the seasonal effects of forest gap sizes on litter lignin degradation, a field experiment using litterbags was conducted in a subalpine forest in western Sichuan, which is located along the upper reaches of the Yangtze River and in the eastern part of the Tibetan Plateau. Litterbags containing red birch (Betula albo-sinensis) and Minjiang fir (Abies faxoniana) foliar litter were placed on the forest floor under four gap sizes conditions:a closed canopy, a large gap, an intermediate gap and a small gap. The litterbags were sampled at the onset of the soil freezing, during soil deep freezing and soil thawing, and during the early, middle and late growing season. The experiment was conducted from November 2011 to October 2012. The lignin concentrations of the litter were measured, and the rates of lignin degradation were calculated. The results indicated that season and gap size had significant effects on lignin degradation of both red birch and Minjiang fir litter. Over the course of the one-year study period, lignin losses from the foliar litter were 21.53-27.65% for red birch and-7.95-19.40% for Minjiang fir, across the four size gaps. The large gap promoted the degradation of lignin in the Minjiang fir litter during winter, and that of lignin in the red birch litter during the growing season. Conversely, the large gap inhibited the degradation of lignin in the red birch litter during winter, while the lignin degradation rate of the Minjiang fir litter during the growing season was as follows:closed canopy > large gap > intermediate gap > small gap. In addition, a step-wise regression analysis result revealed that lignin degradation of foliar litter is significantly correlated with negative accumulated temperature and frequency of soil freeze-thaw cycle in winter, suggesting that the degradation of lignin that occurs during winter is mainly driven by physical damage to its molecular structure. Furthermore, close correlations were detected between litter lignin degradation rate and average temperature, and positive accumulated temperature, suggesting that biological processes may contribute to lignin degradation during the growing season. These results imply that differences in forest gap size significantly affect the lignin degradation process of foliar litter in subalpine forests; however, the effects may depend on plant species and season. 参考文献 相似文献 引证文献

Effects of litter quality and climate change along an elevational gradient on litter decomposition of subalpine forests, Eastern Tibetan Plateau, China

Temperature and freeze-thaw events are two key factors controlling litter decomposition in cold biomes. Predicted global warming and changes in freeze-thaw cycles therefore may directly or indirectly impact litter decomposition in those ecosystems. Here, we conducted a 2-year-long litter decomposition experiment along an elevational gradient from 3000 to 3600 m to determine the potential effects of litter quality, climate warming and freeze-thaw on the mass losses of three litter types [dragon spruce (Picea asperata Mast.), red birch (Betula albosinensis Burk.), and minjiang fir (Abies faxoniana Rehd. et Wild)]. Marked differences in mass loss were observed among the litter types and sampling dates. Decay constant (k) values of red birch were significantly higher than those of the needle litters. However, mass losses between elevations did not differ significantly for any litter type. During the winter, lost mass contributed 18.3–28.8 % of the net loss rates of the first year. Statistical analysis showed that the relationships between mass loss and litter chemistry or their ratios varied with decomposition periods. Our results indicated that short-term field incubations could overestimate the k value of litter decomposition. Considerable mass was lost from subalpine forest litters during the wintertime. Potential future warming may not affect the litter decomposition in the subalpine forest ecosystems of eastern Tibetan Plateau.