Nutrient cycling characteristics of Quercus acutissima and Pinus massoniana mixed forest in the Three Gorge Reservoir area, China

The cycling characteristics of nitrogen(N), phosphorus(P) and potassium(K) of the Quercus acutissima and Pinus massoniana mixed forest which is the most common forest type in the Three Gorge Reservoir areas in China, were systematically analyzed. The results showed that N, P and K accumulated in the plant pool and in the litter pool, while total N, P, and K were deficient in the soil pool and in the forest systems. Contents of N in the soil of depth 20—40 cm were the key factor limiting growth of trees. The biological outside cycling coefficients were 878, 725 and 117 times of inside cycling coefficients of N, P and K, respectively. 3392, 1026 and 1588 kg of N, P and K return to the litter pool from branches, leaves and throughfall per year, but, 1431, 132 and 1048 kg of N, P and K return to the soil from litter pool per year respectively. It is clear that 58% of N, 87% of P, and 34% of K are lost by surface runoff per year. 549%, 130%, and 834% of N, P and K withdraw from leaves to branches, 499%, 199% and 730% of N, P and K withdraw from branches to trunks per year, respectively.

中国森林遥感Rao′s Q指数时空演变

明确宏观森林植物多样性时空分布格局,对于评估森林生态工程效果以及有效开展区域生物多样性保护工作具有重要意义。遥感生物多样性研究能够弥补原位观测在时空连续性方面的不足,研究旨在为区域尺度生物多样性研究引入一种新方法——遥感Rao′s Q指数。结果表明:基于归一化植被指数(NDVI)计算的Rao′s Q指数与收集的物种丰富度在空间分布上基本一致,且两者的数值拟合通过极显著检验(R^(2)=0.66,P<0.001),Rao′s Q指数随物种丰富度增加而增加,适用于表征宏观尺度跨气候带地区的森林植物多样性。2000—2017年间,中国森林的Rao′s Q指数时空分布基本一致,整体呈南高北低的态势;不同时段中均以降低为主,降低面积占总面积的44.23%—54.08%,武夷山-南岭一带增高特征凸显,而2010—2017年也表现出降低特征,该区域森林植物多样性本底丰富,应加强管控力度,阻止降低热点区扩散。引入遥感Rao′s Q指数有效表征区域森林植物多样性分布特征,可为区域生态质量评估提供一种新的监测指标,进而为森林植物多样性保护及区域生态质量改善相关政策制定提供支撑。

采用恒Q调制包络的合成语音伪装检测方法

针对传统的声学特征参数对合成语音伪装检测时存在的准确度低、未知类型合成语音检测效果较差、在噪声环境中表现欠佳的情况,提出了一种采用恒Q调制包络(constant Q modulation envelope,CQME)的合成伪装语音检测方法。该方法基于语音时域包络中包含的丰富信息,而合成语音与真实语音的包络在细节上存在较大差异,利用恒Q变换(constant Qtransform,CQT)得到语音调制包络谱,并计算每个频率成分的均方根,获得CQME特征向量。再用该特征向量训练随机森林分类器,实现真伪语音的判别。实验结果表明,在ASVspoof 2019数据集上,CQME特征训练的随机森林具有较高的检测性能,对未知类型的合成语音也具有较好的检测效果。并且在多种噪声条件下,该方法仍表现出较高的检测性能,具有很好的噪声鲁棒性。

基于随机森林的认知诊断Q矩阵修正

Q矩阵是认知诊断的核心,专家构建的Q矩阵通常存在一定错误,会降低估计精度,因而需要进行修正。采用随机森林(random forest,RF)算法,以PVAF、对数似然值、改造后的R统计量为特征训练模型,提出了机器学习视角的Q矩阵修正新方法(RF-P、RF-L、RF-R),并开展模拟与实证研究验证性能。研究结果表明:(1)三种模型的准确率、召回率、精确率、F1、Kappa等评估指标均在0.75以上;(2)模拟研究中,基于三种随机森林模型的新方法在整体上均比最新发表的Wald-XPD法有更好的修正表现,其中以RF-R表现最佳;(3)实证研究中,RF-R修正出了更合理的Q矩阵,有最优的模型-数据拟合结果。

Soil carbon dioxide fluxes of a typical broad-leaved/Korean pine mixed forest in Changbai Mountain, China

The forest ecosystem plays an important role in the global carbon cycling. A study was conducted to evaluate soil CO2 flux and its seasonal and diurnal variation with the air and soil temperatures by using static closed chamber technique in a typical broad-leaved/Korean pine mixed forest area on the northern slope of Changbai Mountain, Jilin Province, China. The experiment was carried out through the day and night in the growing season (from June to September) in situ and sample gas was analyzed by a gas chromatograph. Results showed that the forest floor was a large net source of carbon, and soil CO2 fluxes had an obvi-ous law of seasonal and diel variation. The soil CO2 flux of broad-leaved/Korean pine mixed forest was in the range of 0.302.42 mmol穖-2穝-1 with the mean value of 0.98 mmol穖-2穝-1. An examination on the seasonal pattern of soil CO2 emission suggested that the variability in soil CO2 flux could be correlated with variations in soil temperature, and the maximum of mean CO2 flux occurred in July ((1.27±23%) mmol穖-2穝-1) and the minimum was in September ((0.50±28%) mmol穖-2穝-1). The fluctuations in diel soil CO2 flux were also correlated with changes in soil temperature; however, there existed a factor for a time lag. Soil CO2 flux from the forest floor was strongly related to soil temperature and had the highest correlation with temperature at 6-cm depth of soil. Q10 values based on air temperature and soil temperature of different soil depths were at the ranges of 2.09–3.40.

江西大茅山金盆山常绿阔叶林的Q-型聚类分析

用Q-型聚类分析法对取自大茅山和金盆山的34个常绿阔叶林进行了分类.结果表明,用Q-型聚类分析法所划分的类型与按优势种划分的类型既有相似之点,又有不同之处.但是聚类分析法可以对样地进行更为详细的分类,不但可把取自不同地区而优势种相同的归为一类,也可把它们划分开来;同时还可把优势种不同而地区相同的样地归并到一起.这反映了与地区的经纬度、海拔高度等生境条件相联系的区系组成的变化.根据聚类分析结果把34个样地划分出15个类型.本文还详细介绍了Q-型聚类分析法.

山西省七里峪国家森林公园辽东栎林天然更新研究

以山西省七里峪国家森林公园内的辽东栎林为对象,研究了其林分结构以及天然更新情况。结果表明,目前山西省七里峪国家森林公园内辽东栎林的优势树种仍为辽东栎,且林内的幼树更新状况良好。由更新密度和更新频度可知,辽东栎、五角槭、油松的更新状况较好,其幼树重要值较高,在更新竞争中占优势地位。辽东栎、五角槭、白桦幼树的空间分布格局均为聚集分布,油松幼树在多数标准地内为随机分布。根据实际调查情况来看,更新的辽东栎尚处于幼苗阶段。

辽东栎半同胞家系选择研究

为了确定辽东栎最优家系,于山西省太岳山国有林管理局大南坪中心林场内开展了辽东栎优树选择和苗期试验研究。结果表明,大南坪中心林场辽东栎半同胞家系1年生播种苗苗高变幅为10.4 cm~19.6 cm、地径变幅为0.33 cm~0.56 cm,2年生播种苗苗高变幅为29.7 cm~49.5 cm、地径变幅为0.51 cm~0.70 cm。苗高和地径在家系间差异明显,因此,以苗高和地径进行选择可获得较好的遗传改良效果。根据苗木生长情况,17号、22号、23号、25号家系苗高、地径较大,遗传性状更好,可以对其进行繁育推广,其中,23号家系表现最优。

山西省关帝山国有林管理局真武山林场辽东栎种子特性

在山西省关帝山国有林管理局真武山林场采集成熟的辽东栎种子,通过测定辽东栎种子重量、虫蛀率、淀粉含量及发芽情况,研究其种子特性。结果表明,真武山林场辽东栎种子的单粒重平均为0.24 g~2.07 g,十粒重平均为8.17 g,百粒重平均为86.56 g。种子虫蛀现象严重,虫蛀率为49.6%,其中,蛀孔数1个、蛀孔位于下部的种子最多。种子淀粉含量为12.99%,低于北京地区的辽东栎种子。完整种子的发芽率为3.13%,发芽势为12.5%,发芽指数为0.25,发芽情况较差。

辽东栎次生林人工促进天然更新措施研究

在山西省太岳山地区,选择10个具有代表性的辽东栎次生林,研究不同人工促进天然更新措施对辽东栎幼苗更新的影响。结果表明,清理地表枯落物并刈割地表草本且采取水平阶整地的样地辽东栎幼苗出苗量与保存量明显高于其他处理,其次为清理地表枯落物且采取水平阶整地处理。采取人工促进天然更新措施后,不同林分密度和海拔条件下辽东栎幼苗的出苗量与保存量均无显著差异。综上所述,适宜的人工促进天然更新措施对辽东栎次生林下的幼苗更新促进作用明显,可为辽东栎次生林可持续生长和正向演替提供有利条件。

基于UPLC-Q-Orbitrap HRMS技术的乔林与叶林杜仲叶次生代谢产物比较研究

本文应用超高效液相-四级杆-静电场轨道阱高分辨质谱(UPLC-Q-Orbitrap HRMS)技术,对乔林杜仲叶与叶林杜仲叶进行次生代谢产物分析,并比较其次生代谢产物差异。通过多级离子碎片信息结合mzCloud网络数据库、中药高分辨质谱数据库(OTCML),对照品比对及文献数据库进行准确定性。从乔林杜仲叶与叶林杜仲叶中共鉴定出次生代谢物62种,包括黄酮类9种,苯丙素类9种,环烯醚萜类2种,有机酸类21种,香豆素类5种,其他类成分16种,其中香豆素类成分为首次在杜仲叶中发现的成分。通过主成分分析(PCA)及正交偏最小二乘法-判别分析(OPLS-DA)对各样品数据进行处理,结果乔林杜仲叶与叶林杜仲叶能够很好地区分,根据变量重要性投影(VIP)值>1筛选出两种栽培方式的杜仲叶在相对含量上存在差异的成分有10个,其中独立样本t检验中存在显著差异(P<0.05)的成分有D-(-)-奎尼酸、柠檬酸、4-甲基伞形酮、4,5-二咖啡酰奎宁酸、3′,4′-二羟基苯丙酮。该方法可准确、高效地测定杜仲叶中的化学成分及其相对含量变化,为杜仲叶的品质评价提了供理论依据。

Short-term effects of nitrogen deposition on soil respiration components in two alpine coniferous forests, southeastern Tibetan Plateau

Nitrogen (N) deposition to alpine forest ecosystems is increasing gradually, yet previous studies have seldom reported the effects of N inputs on soil CO2 flux in these ecosystems. Evaluating the effects of soil respiration on N addition is of great significance for understanding soil carbon (C) budgets along N gradients in forest ecosystems. In this study, four levels of N (0, 50, 100, 150 kg N ha^-1 a^-1) were added to soil in a Picea baifouriana and an Abies georgei natural forest on the Tibetan Plateau to investigate the effect of the N inputs on soil respiration. N addition stimulated total soil respiration (Rt) and its components including heterotrophic respiration (Rh) and autotrophic respiration (Ra);however, the promoted effects declined with an increase in N application in two coniferous forests. Soil respiration rate was a little greater in the spruce forest (1.05 μmol CO2 m^-2 s^-1) than that in the fir forest (0.97 μmol CO2 m^-2 s^-1). A repeated measures ANOVA indicated that N fertilization had significant effects on Rt and its components in the spruce forest and Rt in the fir forest, but had no obvious effect on Rh or Ra in the fir forest. Rt and its components had significant exponential relationships with soil temperature in both forests. N addition also increased temperature sensitivity (Q10) of Rt and its components in the two coniferous forests, but the promotion declined as N in put increased. Important, soil moisture had great effects on Rt and its components in the spruce forest (P<0.05), but no obvious impacts were observed in the fir forest (P>0.05). Following N fertilization, Ra was significantly and positively related to fine root biomass, while Rh was related to soil enzymatic activities in both forests. The mechanisms underlying the effect of simulated N deposition on soil respiration and its components in this study may help in forecasting C cycling in alpine forests under future levels of reactive N deposition.

Forest landscape patterns dynamics of Yihe-Luohe river basin

Based on the information from forest resources distribution maps of Luoning County of 1983 and 1999, six indices were used to analyze spatial patterns and dynamics of forest landscapes of the typical region in the middle of the Yihe-Luohe river basin. These indices include patch number, mean patch area, fragment index, patch extension index, etc. The results showed that: (1) There was a rapid increase in the number of patch and total area from 1983 to 1999 in the study area. The fragment degree became very high. (2) The area of all the forest patch types had witnessed great changes. The fractal degree of each forest patch type became big from 1983 to 1999. The mean extension index of Robinia pseudoacacia forest, non-forest, shrub forest, sparse forest, and Quercus species forest increased rapidly, but that of economic forest became zero. The fractal dimension each showed that forest coverage has been promoted. (3) The changes of landscape patterns were different in different geomorphic regions. From 1983 to 1999 the vegetation cover area, the gross number and the density of patch, diversity and evenness of landscape were all reduced greatly in gullies and ravines, but the maximum area and the mean area of patch types were increased. In hilly region, both the forest cover area and the number of patch increased from 1983 to 1999, but the mean area of patch was reduced greatly. In mountain region, even though the area under forest canopy reduced from 1983 to 1999, the patch number was increased greatly, the mean area of all patch types was reduced, the extension index, diversity index and evenness index of landscape were all increased. Furthermore, because of different types of land use, human activity and terrain, the vegetation changes on northern and southern mountain slopes were different. According to these analyses, the main driving forces, such as the policies of management, market economy, influence of human activities etc. are brought out.

Temperature dependence of nitrogen mineralization and microbial status in O_H horizon of a temperate forest ecosystem

It was hypothesized that increasing air and/or soil temperature would increase rates of microbial processes including litter decomposition and net N mineralization, resulting in greater sequestration of carbon and nitrogen in humus, and consequently development in OH horizon （humus horizon）. To quantify the effect of temperature on biochemical processes controlling the rate of OH layer development three adjacent forest floors under beech, Norway spruce and mixed species stands were investigated at Soiling forest, Germany by an incubation experiment of OH layer for three months. Comparing the fitted curves for temperature sensitivity of OH layers in relation to net N mineralization revealed positive correlation across all sites. For the whole data set of all stands, a Q10 （temperature sensitivity index） value of 2.35-2.44 dependent on the measured units was found to be adequate for describing the temperature dependency of net N mineralization at experimental site. Species-specific differences of substrate quality did not result in changes in biochemical properties of OH horizon of the forest floors. Temperature elevation increased net N mineralization without significant changes in microbial status in the range of I to 15℃. A low Cmic /Corg （microbial carbon/organic carbon） ratio at 20℃ indicated that the resource availability for decomposers has been restricted as reflected in significant decrease of microbial biomass.

CO2Emissions from Soils in Subalpine Dark Coniferous Forest Region of Gongga Mountain

A field experiment was carried out to examine the soil respiration rate in Abies fabri forests in Gongga Mountain National Nature Reserve using LI-6400-09 portable soil respiration chamber.The results showed that the soil respiration rate and soil temperature of mature and middle-aged A.fabri forests were different in each month.The soil CO2 emission rates of the two stands had obvious seasonal variation characteristics,which were arranged: summer > autumn > spring > winter;the monthly average soil CO2 emission rate of the mature aged forest ranged from 0.82 to 5.88 μmol/(s·m^2),with the coefficient of seasonal variation of 50.6%;and the average monthly soil respiration rate of middle-aged forest was in the range of 0.52-3.52 μmol/(s·m^2),with the coefficient of seasonal variation of 48.5%.The seasonal variation of soil CO2 emission rate was positively correlated with the 5 cm soil temperature.And the Q10 values of the soil CO2 emission rates in the mature and middle-aged A.fabri forests were 3.2 and 2.6,respectively,and the sensitivity index of CO2 emission to temperature in the mature A.fabri forest was higher than that in the middle-aged forest.

分子标记技术及其在林木QTL定位研究中的应用

林木中的QTL定位研究发展的比较晚,分子标记技术的产生和发展极大地促进了林木QTL定位研究和林木分子育种的工作。文章概述了RFLP,RAPD,SSR,ISSR,AFLP以及SNP分子标记技术的原理、特点,并论述了近年来这几种分子标记技术在林木QTL定位研究中的应用。

Soil CO2 Efflux Dynamics and Its Relationship with the Environmental Variables in a Sub-Tropical Mixed Forest

Soil CO2 efflux is an ongoing process of respiration from soil;plant parts/ microbes below the ground to the atmosphere which is known for faster cycling of carbon sources. A large portion of carbon sequestered and fixed by forests is returned to the atmosphere through soil CO2 efflux and multiple controlling parameters mainly temperature, precipitation, and growth factors interact with the soil CO2 efflux variation. This study assessed the soil CO2 efflux every month for consecutive 2-years (August 2015 to July 2017) by using the closed chamber method to determine the role of ecological parameters that govern the soil CO2 efflux and its temporal modification in a sub-tropical mixed forest of central region in Nepal. The results of this study manifested that soil CO2 efflux accounted 63.2% (y = 31.96e0.128x), 71.3% (y = 44.77e0.123x) and 64.5% (y = 44.11e0.117x) variations in soil temperature with significantly (p < 0.05) exponential positive relation in the year 2015/2016, 2016/2017 and the two years when merged. And the temperature sensitivity value (Q10) of the soil CO2 efflux was 3.6, 3.4, and 3.2, respectively. Soil water content also expressed significantly (p < 0.05) positive exponential effect on soil CO2 efflux and accounted 62.0% (y = 138.3e0.057x), 46.1% (y = 88.42e0.052x) and 40.5% (y = 133.1e0.0447x) in its variability in different years and the merged years. Evident variations of soil CO2 efflux, soil temperature, soil water content, and litter were observed in the forest seasonally and inter-annually. Two years mean total annual soil CO2 efflux of the forest was estimated at 904.76 g C·m-2·y-1. The study revealed that sub-tropical forests could be more influenced by precipitation regimes in progressing warm climates i.e. vulnerable to climate change, illustrating the comprehensive dynamics of the representative forest carbon cycle in the tropical region.

东灵山辽东栎林木本植物多样性的研究

应用α多样性和β多样性指数对东灵山地区辽东栎林在不同样地环境梯度的物种多样性进行了初步研究。结果表明 :不同样地梯度的辽东栎林乔灌木物种α多样性逐步降低 ,但变化幅度较小 ,群落物种组成趋于简单。不同样地梯度内辽东栎林乔木物种的 β多样性的二元属性测度与数量数据测度结果反映出乔木物种和灌木物种对整个辽东栎林多样性的影响是不同的。数量数据 β多样性测度综合地考虑了物种数与物种数量对 β多样性变化的影响 ,适于对单优群落物种多样性进行分析。在中海拔样地梯度 ,辽东栎林乔灌木物种各样地对之间的 β多样性数值较小 ,表明辽东栎林内物种替代速率较低 ,物种组成相对稳定 。

子午岭地区辽东栎和油松林建群种的更新生态位宽度分析

通过实地调查并采用Levins生态位宽度指数对子午岭地区主要树种辽东栎(Quercus liaotungensis)和油松(Pinus tabulaeformis)的幼苗、幼树和成树在不同坡向的辽东栎林、油松+辽东栎混交林和人工油松林3种群落中的生态位宽度进行了分析研究。结果显示:(1)辽东栎和油松的更新生态位宽度在不同群落中各不相同,成树的生态位宽度与群落类型一致;(2)辽东栎幼苗和幼树在阳坡和阴坡人工油松林中的生态位宽度分别是0.951、0.95和0.98、0.94,且生态位宽度显著大于其它2个群落,表明辽东栎幼苗和幼树能很好地适应人工油松林的环境条件;(3)在阳坡,油松幼苗的生态位宽度在辽东栎林最大为0.79,且极显著大于其它2个群落,而阳坡油松幼树的生态位宽度在人工油松林中最大为1.00;在阴坡,油松幼苗的生态位宽度在人工油松林最大为0.63,而阴坡油松幼树的生态位宽度却在油松+辽东栎混交林最大为0.83,且极显著大于其它2个群落;表明油松幼苗适应阳坡的辽东栎林环境和阴坡的人工油松林环境,油松幼树适应阳坡的人工油松林环境和油松+辽东栎林环境。结果表明,人工种植油松林有利于该地区的植被恢复,人工油松林和油松+辽东栎混交林会在该地区存在较长时间,而阳坡的油松+辽东栎混交林存在时间会更长。

东灵山辽东栎林木本植物种间联结取样技术的研究

在样地面积固定条件下 ,采用样方设计和样带设计 ,探讨了样方数目与面积之间的关系 ,以及样方数目与面积的变化对种间联结的影响。结果表明 :正负关联比、平均物种出现率、多物种间X2 值、物种对间X2 值与显著率以及物种间联结系数的变化范围均可作为确定样方数目与面积的参数。在实际分析中应当综合考虑这些参数 ,进而选择最佳样方数目及面积进行种间联结分析。在样地总面积均为 1 2 0 0m2 条件下 ,样带设计在各项指标上规律性比较明显 ,样方数为 50 ,面积为 2 5m2 最为合适 ;样方设计的各项参数稍差一些 ,需要进一步增加样方总面积才能得到更合适的样方数。分别按选定的最适样方数进行物种对联结性分析 ,对比分析结果显示样带设计对联结性和关联程度的检测效果好于样方设计 ,它的研究结果更与实际情况相符合。因此 ,在总样地面积有限的情况下 。