Patterns of Ips cembrae(Herr)infestation on trap and standing trees of European larch(Larix decidua Mill.)

The large larch beetle,Ips cembrae,is a significant pest causing the death of larch.In 2020,the attack density of I.cembrae on larch trap trees and standing trees was evaluated using sample sections placed along the trunk.As a defensive measure against I.cembrae,trap trees were highly effective in both spring and summer.The attack density increased with increasing trap tree surface area/volume.Galleries were established evenly throughout the entire trunk including the thin upper portion.When the number of trap trees was low and their capacity full,a continual aggregation of adults occurred due to pheromone communication,leading to attacks on healthy standing trees in the immediate vicinity.It was found that I.cembrae attacked standing trees from the trunk base,with a continual colonization of the stem up to 70%of the tree height in a time-differentiated progression of development stages.The attack density of I.cembrae on standing trees was up to 40%lower than on the trap trees.

Changing regularity of plant and insect community characteristics due to pest outbreaks in Larix principis- rupprechtii plantations

Research has indicated that simple forest eco-system composition,structure and diversity have uncompli-cated community relationships and insufficient pest control capabilities.To investigate changing characteristics of plant and insect communities in under pest outbreaks in Larix principis-rupprechtii plantations,the research areas were defined as mature(48–50 years)and young(24–29 years)infested stands along with healthy stands.The results show a reduction in the complexity and diversity of plant communi-ties and herbaceous plant guilds(polycultures of beneficial plants)and the complexity and dominance of insect com-munities,especially natural insect enemies.The results also show the relative simplicity of the main factors of commu-nity change and development that represent the characteris-tics of pest outbreaks in L.principis-rupprechtii plantations.The complexity and diversity of plant communities,particu-larly herbaceous plant guilds play a fundamental role in the regulation and development in forest ecosystems.

Interpreting Larix principis-rupprechtii radial growth in northern China based on the Vaganov-Shashkin model

Changes in annual radial growth is an important indication of climate change. Dendroclimatology studies in northern China have focused on linear statistical analysis,but lacking studies based on the process of ring formation to clarify the radial growth of trees. Tree-ring width standard chronology(STD) was established using samples of Larix principis-rupprechtii collected at 2303 m altitude on Luya Mountain. Using the Vaganov-Shashkin(VS) model to simulate growth and development, the internal physiological mechanism of radial growth is identified. It was concluded that:(1) the growing season of L. principis-rupprechtii was May to September;(2) soil moisture was a significant factor in the early and late growing seasons, and temperature was the dominant factor in its main growth period;and(3) formation of narrow ring widths was closely related to drought stress, the development of wide ring widths will be restricted by increasing future temperatures. The VS model is applicable for radial growth simulation of subalpine coniferous forests and for guiding the cultivation of local tree species in the future.

Family selection and evaluation of Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger based on stem analysis data at multiple sites

Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger is an important native tree species in North China with advantages of fast growth,straight trunk,and good wood properties.The multi-year and multi-site breeding research of families of the species has not been reported previously.Based on diameter at breast height(DBH),height and volume of 25 families on four experimental sites,we calculated variance components,genetic parameters,juvenile and mature trait correlations and made genotype main effect plus genotype×environment interaction effect(GGE)biplot based on the breeding values estimated using the method of best linear unbiased prediction(BLUP).Compared with height,DBH and volume had higher heritability and larger variation coefficients,making them the more suitable traits for family selection and evaluation.Based on these,GGE biplots containing 20 combinations of site×age were drawn using data at 13 to 17 years when the interactions between family and location were strong.Test sites classifications based on DBH,and volume were inconsistent,with two categories for DBH and one for volume.The Guyuan site was the most suitable with strong discriminating ability,high representativeness and stability among tree ages.Integrating the ranking results of DBH and volume,families 66,76,82 and 111 were high-yielding and stable,families 78 and96 were high-yielding with above average stability,families72 and 79 were high-yielding with below average stability,whereas stability of family 100 was inconsistent between DBH and volume.Early selection based on DBH was convenient and reliable,and can be made at seven years.This study provides support for the selection of Larix gmelinii var.principis-rupprechtii families in Hebei province and an example for the application of stem analysis data from multiple sites in tree breeding.

Altitude shape genetic and phenotypic variations in growth curve parameters of Larix kaempferi

To study the effects of geoclimatic variables of provenances on growth phenotypes and selected plus provenances,over 3000 trees of 22-year-old Larix kaempferi were evaluated from trials established in two climate zones for provenance selection and to explore the influence of climate variables on provenance performance.The material was replicated plantings of 84 open pollinated families from six provenances distributed in the mountains of central Japan.Provenance variation was observed in most age groups and the heritability of growth traits showed large differences.The phenotypic maximum value of height and diameter were significantly positive with altitude,and mean annual precipitation being important factors.Diameter at breast height growth was significantly negative with altitude and spring rainfall.The Ina provenance of relatively high altitudes,was well adapted to a variety of climates.Altitude might be the driving force for phenotypic and genetic variations and local adaptation.

Analysis of genetic diversity and prediction of Larix species distribution in the Qinghai–Tibet Plateau,China

Larix resources in the Qinghai-Tibet Plateau have important ecological and economic values.However,the lack of genetic diversity background and related research hinders the development of conservation strategies.In this study,genetic diversity and distribution of fi ve Larix species were investigated.Using 19 polymorphic microsatellite markers to study 272 representative individuals from 13 populations,the results show low genetic diversity at the population level,with variation explained mainly by diff erentiation among populations.The Larix populations were classifi ed into two clades,one formed by eight populations,including three of the species in this study,L.kongboensis,L.speciosa,and L.potaninii var.australis.The other clade consists of fi ve populations,including the other two species in this study,L.griffi thii and L.himalaica.Genetic distance of the species was aff ected by geographical isolation and genetic diversity was mainly aff ected by altitude.The area suitable for Larix spp.decreased during the Last Glacial Maximum compared to the current distribution according to the niche model,but should increase in future climate scenarios(2050s),expanding westward along the Himalayas.These results provide an important scientifi c basis for the development of conservation strategies and further the sustainable utilization of Larix resources in the Qinghai-Tibet Plateau.

华北落叶松林林分密度对林下更新影响研究

[目的]华北落叶松(Larix principis-rupprechtii)是寒温带针叶林的优势树种之一。探究华北落叶松的更新特征,可为深入探测华北落叶松林天然更新潜在的生态学机制提供依据。[方法]以关帝山华北落叶松林为研究对象,设置3种林分密度类型,分析不同林分密度林下更新苗组成、结构及空间格局特征。[结果]中密度(825~875株·hm^(-2))华北落叶松林林下更新状况良好,更新苗数量明显增多(3500株·hm^(-2)),低龄级更新苗较多,高龄级的更新苗相对较少,更新苗龄级结构呈连续及相对稳定的分布;而低密度(575~700株·hm^(-2))和高密度(1000~1125株·hm^(-2))华北落叶松林下更新不佳,更新苗数量明显减少(≤1250株·hm^(-2)),高密度林下更新苗龄级结构间断,幼苗到幼树的过渡不连续。从更新苗的生长情况看,低密度林分中林下更新苗的株高、地径生长表现最好。更新幼树中的优势树种在3种密度的林分中均呈现明显的集聚分布。低密度和中密度华北落叶松林下更新幼苗的空间异质性强,高密度林下更新幼苗的空间异质性弱。更新幼苗空间变异主要由结构性因素引起。[结论]林分密度过密或过疏都不利于华北落叶松更新,及时进行密度调控有利于华北落叶松林的可持续发展。

施肥对日本落叶松母树种子球果和形质特征的影响

以日本落叶松1.5代和2代种子园为研究对象,施用N肥、P肥、K肥,采用正交试验设计,调查并分析了施肥处理对日本落叶松种子园母树球果和种子特性的影响,有效提高落叶松种子园种子产量,满足生产上对落叶松良种的需求。结果表明:从球果形质特征上看,施肥可显著促进日本落叶松1.5代和2代种子园单果质量、球果纵径和横径的增加,其中,1.5代种子园中,“N(0.4 kg/株)+P(0.6 kg/株)+K(0.6 kg/株)”处理的单果质量和球果纵径最大,分别达到4.01g和3.14cm,分别为CK的1.79倍和1.37倍,“N(0.2kg/株)+P(0.6kg/株)+K(0.4kg/株)”处理的球果横径最大,达到2.26cm,为CK的1.1倍;2代种子园中,“N(0.2 kg/株)+P(0.8 kg/株)+K(0.6 kg/株)”处理的单果质量、球果纵径和横径等指标均较高,分别达到8.23g、3.74 cm和2.58 cm。从种子形质特征上看,施肥对日本落叶松1.5代、2代种子园种子形质指标的影响有限,施肥仅对1.5代种子园种子纵径、横径和侧径及2代种子园千粒质量有显著影响。较高的K肥和适量的N肥施用量有利于球果和种子的增大,日本落叶松种子园施肥较优方案为N肥0.4 kg/株、P肥0.6 kg/株、K肥0.6 kg/株。

基于遗传效应和气候变量的日本落叶松微纤丝角预测

【目的】分析遗传效应和气候变量对日本落叶松木材微纤丝角的影响,建立预测模型,预测终端收获木材的质量,旨在提高遗传材料的选育效率和促进目标材种的定向培育。【方法】以20个日本落叶松无性系为研究对象,通过木芯取样测定了林龄从4年到15年连续12个年轮的微纤丝角,分析了微纤丝角与林龄和年轮宽度的关系,建立了微纤丝角基础预测模型,然后对微纤丝角和气候变量进行相关性分析,采用混合效应模型构建了含有遗传效应和气候变量的日本落叶松微纤丝角预测模型。【结果】(1)微纤丝角随着林龄的增加呈减小趋势,随年轮宽度的增加呈增加趋势,不同无性系间微纤丝角变化规律明显不同。(2)含有林龄和年轮宽度的基础模型确定系数(R^(2))为0.43,均方根误差(RMSE)为4.391;加入平均年降水量和冬季平均降水量后模型R2为0.54,RMSE为4.039;采用混合模型建立的含遗传效应和平均年降水量、冬季平均降水量的微纤丝角预测模型R^(2)为0.81,RMSE为3.061。(3)平均年降水量和冬季平均降水量增加会增大日本落叶松微纤丝角,两个气候变量解释了微纤丝角变异的11%;遗传效应对日本落叶松微纤丝角变异有重要影响,可解释微纤丝角变异的27%。【结论】相较于平均年降水量和冬季平均降水量,遗传效应对木材微纤丝角影响更大。而且不同无性系的微纤丝角对气候因素变化的响应不同,无性系I6-7-075、I8-4-30和J28-6对于气候变化更钝化,是生态适应性更强的无性系,适合进一步在日本落叶松适生区推广应用。

气候对不同林型兴安落叶松林生产力的影响

以内蒙古大兴安岭地区两种林型的兴安落叶松(Larix gmelinii)天然林为对象,运用树木年轮学与异速生长方程模型,推算过去20 a杜香(Ledum palustre L.)-兴安落叶松林及草类-兴安落叶松林净初级生产力(N_(PP))的年际变化,结合中国气象数据网获取的气象数据,分析气候因子对不同林型兴安落叶松林N_(PP)的影响。结果表明:两种林型生物量呈逐年上升的趋势,N_(PP)呈“上升-下降-上升”的波动式上升趋势。不同林型N_(PP)与各气候因子的相关分析表明,2000—2020年温度(T)对两种林型兴安落叶松林N_(PP)起正向影响,而降水(P)对草类-兴安落叶松林N_(PP)起正向影响。由于气候的“滞后效应”,杜香-兴安落叶松林N_(PP)与上一年8月份月平均最高温度呈极显著正相关,草类-兴安落叶松林N_(PP)与上一年11月份月平均温度、上一年7月份降水量呈显著正相关。

配方施肥对华北落叶松各器官非结构性碳水化合物特征的影响

探究配方施肥对华北落叶松针叶、枝条和细根的非结构性碳水化合物(NSC)的影响,为华北落叶松高效施肥技术提供参考依据。以32年生华北落叶松为研究对象,采用N、P、K三因素三水平正交设计L 9(34),以不施肥为对照,研究配方施肥对华北落叶松针叶、枝条和细根的NSC及组分(可溶性糖、淀粉)含量的影响,分析华北落叶松各器官NSC及组分含量的相关关系。结果表明,1)华北落叶松针叶、枝条和细根非结构性碳水化合物含量随月份呈显著变化,基本均在10月达到峰值,且3个器官中NSC均以可溶性糖为主。2)各施肥处理对针叶、枝条和细根的NSC及组分含量的表现不同,其中针叶和细根的NSC含量分别在处理T4和T8较CK平均增幅最大,为29.65%、23%;而枝条的NSC含量和可溶性糖含量与CK的平均增幅相比表现为减少。3)相关性分析显示:针叶、枝条和细根的NSC含量与其可溶性糖含量和淀粉含量间均存在极显著正相关(P<0.01);细根NSC含量与针叶和枝条的可溶性糖含量均存在显著负相关(P<0.05)。4)N、P、K肥对华北落叶松各器官NSC及组分含量均有一定影响;N肥对细根NSC及组分含量均产生显著增加影响,P肥和K肥对各指标显著性影响有所不同;改善华北落叶松非结构性碳水化合物特征的最佳施肥方案为N 3P 3K 2(N 528.78 g·株^(-1)、P 1621.58 g·株^(-1)、K 172.98 g·株^(-1))。施用适宜的N、P、K配方能有效改善华北落叶松针叶、枝条和细根的NSC及组分含量,且各器官在生长过程中存在相互平衡和动态调配的关系。

日本落叶松种子园和人工林优树自由授粉家系苗期选择

探究日本落叶松种子园和人工林优树自由授粉家系苗期生长性状遗传变异规律,为优良家系造林和后期遗传改良提供参考。以沙坝国家落叶松/云杉良种基地日本落叶松初级无性系种子园25个自由授粉家系和30个人工林优树自由授粉家系为试验材料,种子园混合种子苗作为对照,田间试验采用随机完全区组试验设计,在沙坝国家落叶松云杉良种基地苗木培育圃进行苗期生长试验。数据采用SPSS 16.0进行方差分析、多重比较,并估算遗传力和遗传增益,以2年生苗地径、苗高、新梢生长量为指标,采用Brykin多性状综合评定法进行家系评价和选择。种子园、人工林优树自由授粉家系1年生苗和2年生苗生长性状(地径、苗高、2年生苗新梢生长量)具有丰富的遗传变异,生长性状间具有显著(P<0.05)或极显著(P<0.01)正相关关系,家系选择潜力大。种子园自由授粉家系2年生苗地径、苗高、新梢生长量的表型变异系数分别是27.61%、36.82%、44.28%,家系遗传力依次为0.76、0.79、0.79,人工林优树自由授粉家系地径、苗高、新梢生长量的表型变异系数分别是25.57%、32.94%、38.83%,家系遗传力依次为0.90、0.92、0.92,属较高遗传力。家系生长性状受强的遗传控制,具有一定的稳定遗传能力,家系选择的遗传增益显著。按照50%的入选率初步选择苗期表现好的优良家系,种子园有种1、种25、种8、种34、种26、种12、种16、种20、种2、种100、种7、种21、种101共13个家系入选,入选家系地径、苗高、新梢生长量的遗传增益达到1.89%、6.18%、7.65%;人工林优树自由授粉家系有优19、优8、优2、优28、优30、优3、优7、优1、优18、优6、优15、优26、优25、优24、优13共15个家系入选,入选家系的地径、苗高、新梢生长量的遗传增益分别是3.73%、9.31%、11.19%。不论种子园还是人工林优树自由授粉家系,采用Brykin综合评价法选择的优良家系恰好是将苗高最大的家系入选。因此,建议日本落叶松自由授粉家系苗期采用单一性状——苗高作为评价和选择指标,会更加直观、经济、有效。在50%的入选率下,种子园、人工林优树自由授粉家系苗期分别有13个和15个家系入选,苗期初选家系为造林试验和后期遗传改良提供参考,有效减小田间试验规模,提高选择效率。苗高作为评价和选择指标,在生产中更加直观、方便、实用。

^(60)Co-γ辐照对1年生长白落叶松苗木生长影响初探

落叶松是我国北方地区重要的速生用材树种,为满足生产上对落叶松良种的需求,该研究采用不同^(60)Co-γ辐照剂量辐照长白落叶松混系种子,相同^(60)Co-γ辐照剂量(20 Gy)辐照落叶松不同家系种子,播种后统计出苗率,测定苗高、地径和侧枝数等生长指标,分析^(60)Co-γ辐照剂量对落叶松苗木生长的影响,以期建立快速获得落叶松良种的方法。结果表明,1年生落叶松苗高、地径、侧枝数和出苗率分别为15.68~22.39 cm、0.28~0.42 cm、1.03~4.01个和7.7%~37.52%,且总体表现为随辐照剂量的增加而降低的趋势,其中,20 Gy和30 Gy处理的苗高、地径、侧枝数和出苗率与对照较接近。不同家系在^(60)Co-γ辐照处理后,苗高、地径、侧枝数和出苗率间存在一定的差异,这些差异一方面来源于家系本身的生长特性,另一方面来源于^(60)Co-γ辐照处理。该研究为后续采用^(60)Co-γ辐照处理来创制落叶松良种提供了技术支撑。

Stem Respiration of a Larch (Larix gmelini) Plantation in Northeast China

Stem respiration is an important part of the activity of a tree and is an important source of CO2 evolution from a forest ecosystem. Presently, no standard methods are available for the accurate estimation of total stem CO2 efflux from a forest. In the current study, a 33-year-old (by the year 2001) larch (Larix gmelini Rupr.) plantation was measured throughout 2001-2002 to analyze its monthly and seasonal patterns of stem respiration. Stem respiration rate was also measured at different heights, at different daily intervals and any variation in the larch plantation was recorded. The relationship between stem temperature, growth status and respiration rate was analyzed. Higher respiration rates were recorded in upper reaches of the larch tree throughout the season and these were affected partially by temperature difference. Midday depression was found in the diurnal changes in stem respiration. In the morning, but not in the afternoon, stem respiration was positively correlated with stem temperature. The reason for this variation may be attributed to water deficit, which was stronger in the afternoon. In the larch plantation, a maximum 7-fold variation in stem respiration was found. The growth status (such as mean growth rate of stem and canopy projection area) instead of stem temperature difference was positively correlated with this large variation. An S-model (sigmoid curve) or Power model shows the greatest regression of the field data. In the courses of seasonal and annual changes of stem respiration, peak values were observed in July of both years, but substantial interannual differences in magnitude were observed. An exponential model can clearly show this regression of the temperature-respiration relationship. In our results, Q(10) values ranged from 2.22 in 2001 to 3.53 in 2002. Therefore, estimation of total stem CO2 efflux only by a constant Q(10) value may give biased results. More parameters of growth status and water status should be considered for more accurate estimation.

内蒙古旺业甸华北落叶松人工林空间结构分析及其优化

以内蒙古赤峰市旺业甸实验林场未采伐的落叶松人工林幼龄林(18 a)、近熟林(34 a)及成熟林(48 a)为对象,分析3种林分空间结构,对结构不理想的林分进行空间结构优化。采用角尺度、大小比数、混交度及竞争指数4个林分空间结构参数,构建空间结构评价指数,对其空间结构进行优化。结果表明,旺业甸落叶松人工林幼龄林呈随机分布,近熟林及成熟林呈均匀分布,靠近随机分布,林木大小分化不明显,林木竞争较大,评价等级均为2级较差。根据评价结果,采用20%采伐强度后,竞争指数明显降低。采伐前后落叶松幼龄林空间结构综合指数由0.247增加为0.308,近熟林由0.312增加为0.406,成熟林由0.265增加为0.319,近熟林评价等级由2级提升为3级。通过对内蒙古赤峰市旺业甸林场的华北落叶松人工林空间结构分析与优化,可以较好地改善当地华北地区华北落叶松人工林林分空间结构,为我国华北落叶松人工林经营提供数据支持。

林龄和造林密度对塞罕坝华北落叶松纸浆林材性影响效应

【目的】探究林龄和造林密度对华北落叶松纸浆林材性的影响,为塞罕坝地区定向培育华北落叶松纸浆人工林提供理论和实践依据。【方法】以3种林龄(15、20、25 a)、3种造林密度(低密度2500株·hm^(-2)、中密度3300株·hm^(-2)、高密度4400株·hm^(-2))的华北落叶松人工林为研究对象,采用双因素完全随机区组法研究造林密度对于林木材性的影响。【结果】1)木材基本密度仅在高密度水平下20 a(0.439 g·cm^(-3))和25 a(0.387 g·cm^(-3))林分间差异显著(P<0.05),而不同林龄水平下造林密度对其无显著影响。2)晚材率在高密度时,随着林龄的增加先显著增大后显著减小(P<0.05),与木材基本密度的变化规律相似;15 a时,低密度(19%)林分显著小于其他两个林分(P<0.05)。3)年轮宽度在15和20 a时,随着造林密度的增大显著减小,且峰值及其出现峰值的轮龄逐渐变小;而在25 a不同造林密度间无明显差异,且峰值(5.9、6.1、6.2 mm)及其出现的轮龄(7、6、8 a)都相近,认为林分可能由25 a进入生长稳定期。4)年轮宽度在不同密度水平下,随着林龄的增长,林木形成层分蘖活动逐渐减弱,细胞间间隙变小,木材材质更加致密,不断变小。5)当林龄和造林密度较小时,林木生长速度较快,纤维细胞在横向和纵向方向上迅速且均匀生长、细胞壁较厚,纤维长宽比小、壁腔比大;待林龄和林分密度逐渐增大,纤维细胞横向生长减缓、细胞壁逐渐变薄,纤维长宽比增大(56.40~77.15)、壁腔比变小(0.48~0.25)、综纤维素含量不断减小(73.18%~53.09%),说明此时纤维细胞已经充分伸长。6)酸不溶木素含量在各林分间浮动范围不大(20.98%~29.74%),随着林龄的增长略有增高。1%NaOH抽出物、苯醇抽出物和灰分含量在林龄和造林密度水平上都无明显一致的变化规律。7)单位公顷纸浆产量在各林龄水平下仅在15 a不同造林密度间差异显著,且随着造林密度的增加都呈现出上升的趋势,所有林分中含量最高的为15 a高密度林分(68.47 t·hm^(-2))。低、中密度水平下的林分,林龄越大单位公顷纸浆产量显著增大,而高密度林分在不同林龄间差异不显著。【结论】根据主成分分析法和综合排名初步认为,15 a林分的2500株·hm^(-2)材性最好,可作为塞罕坝地区纸浆材定向培育的选择方向。

应用地基激光雷达三维点云数据构建长白落叶松树干削度方程

使用地基激光雷达(TLS)三维点云数据提取的落叶松干形数据,构建树干削度方程,为落叶松干形精准预测提供依据。以吉林省一面山林场和杨木林林场落叶松人工林为研究对象,获取71株落叶松点云信息,并提取树干干形数据。选择简单、可变指数、三角函数和分段函数等9个基础削度方程进行比较,利用分位数回归和广义加性模型方法构建削度方程。结果表明:在9个基础削度方程中,Bi(2000)削度方程的拟合效果最好,多重共线性指标条件数也小于100;Bi(2000)基础削度方程构建的分位数回归模型,在9个分位点(τ=0.1、0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9)处均能收敛,其中在τ=0.5的分位点处的拟合效果最好,略优于非线性回归的拟合结果。在以相对直径为因变量,以相对高的平方根、胸径的平方和树高为自变量的广义加性削度方程中,6种光滑样条函数(三次回归样条函数(CR)、B-样条函数(BS)、薄板回归样条函数(TP)、P-样条函数(PS)、Duchon样条函数(DS)和高斯过程平滑样条函数(GP))的拟合效果相差不大,但广义加性削度方程使用(DS+CR)光滑样条函数比一种光滑样条函数的拟合效果好(相对误差4.407、均方根误差1.158、确定系数0.966),广义加性削度方程的各检验统计量均优于基础削度方程和分位数回归削度方程,且在树干相对高度10%~80%,广义加性削度方程也表现最优(相对误差4.534、均方根误差1.191、确定系数0.964)。因此,(DS+CR)组合光滑样条函数的广义加性削度方程预测精度最高,可用于该区域的落叶松干形预测。

林火强度对兴安落叶松林土壤氮循环功能基因的影响

为了探究林火强度对土壤氮素循环的影响,本研究以内蒙古大兴安岭兴安落叶松林火烧迹地为研究对象,通过DNA提取及定量PCR分析测定了不同火烧强度样地内土壤氮循环功能基因丰度以及土壤基本的理化性质。结果表明:固氮nifH功能基因丰度随着火烧强度的增加而减少,而硝化amoA-AOA和amoA-AOB功能基因丰度呈相反变化趋势;反硝化nirS,nirK和nosZ功能基因丰度在重度火烧后显著降低,在轻度火烧后显著升高。火烧同样也会对土壤基本理化性质产生显著影响,RDA分析和Pearson相关性分析表明土壤氮循环功能基因与土壤理化因子之间存在密切的联系,有机碳、速效磷、全氮含量和pH值是影响火后土壤氮循环功能基因差异变化的主要因子。本研究为火干扰对土壤氮素循环的影响机制和火后植被快速更新提供数据支撑。

基于TLS引入局部密度因子的落叶松削度方程构建

将局部密度因子引入削度方程,通过地基激光雷达对黑龙江省佳木斯市桦南县孟家岗林场5块落叶松人工林进行扫描,采集的点云数据用于提取落叶松树高、胸径以及不同相对高度处直径,基于Kozak可变指数削度方程构建引入局部密度因子的削度方程,削度方程拟合结果为调整决定系数R^(2)_(adj)=0.935,均方根差RMSE=0.7356,平均偏差Bias=0.8693。研究表明,引入局部密度因子的削度方程具有良好的拟合精度;对比传统Kozak削度方程和引入全局密度因子的削度方程,引入局部密度因子的削度方程拟合效果更好;落叶松的削度方程其局部密度因子的计算范围与树高和胸径呈正相关。试验结果可以为孟家岗林场科学合理的造材提供理论依据,初步揭示了局部密度因子对于落叶松树干干形的影响。

大兴安岭不同演替阶段天然林物种多度格局模拟

为实现大兴安岭地区落叶松天然林的全周期可持续经营,以新林林业局翠岗林场3块100m×100m不同演替阶段(白桦林、落叶松-白桦混交林和落叶松林)的天然林固定调查样地数据为基础,采用统计模型(对数正态模型)、生态位模型(断棍模型、生态位优先占领模型、Zipf模型、Zipf-Mandelbrot模型)和中性模型(群落零和多项式模型、Volkov模型)对不同演替阶段天然林的乔木层、幼苗层和由乔木层划分的不同林层的物种多度格局进行拟合,并用χ~2检验和Kolmogorov-Smirnov检验选择最佳模型。结果表明:(1)在大兴安岭地区不同演替阶段的落叶松天然林群落中,Zipf-Mandelbrot模型的拟合效果均最好。(2)对数正态模型对于稳定的演替阶段白桦林和落叶松林的群落相较于过渡阶段群落落叶松-白桦混交林的物种多度分布的拟合效果更好。(3)在大兴安岭地区落叶松天然林中,生境过滤主导群落构建,随着群落不断演替生境过滤和中性过程减弱。(4)天然林群落乔木层的群落构建过程与乔木层内不同生长阶段林层的构建过程不同,生境过滤过程在落叶松林乔木层中逐渐减弱,而在落叶松林不同生长阶段的林层和更新层中增强。