Water yield and biomass production for on a eucalypt-dominated Mediterranean catchment under different climate scenarios

Worldwide,forests are vital in the regulation of the water cycle regulation and in water balance allocation.Knowledge of ecohydrological responses of production forests is essential to support management strategies,especially where water is already scarce.Shifting climatological patterns are expected to impact thermopluviometric regimes,water cycle components,hydrological responses,and plant physiology,evapotranspiration rates,crop productivity and land management operations.This work(1)assessed the impacts of different predicted climate conditions on water yield;(2)inferred the impacts of climate change on biomass production on eucalypt-to-eucalypt succes sion.To this end,the widely accepted Soil and Water Assessment Tool(SWAT)was run with the RCA,HIRHAM5 and RACMO climate models for two emission scenarios(RCP 4.5 and8.5).Three 12-year periods were considered to simulate tree growth under coppice regime.The results revealed an overall reduction in streamflow and water yield in the catchment in line with the projected reduction in total annual precipitation.Moreover,HIRHAM5 and RACMO models forecast a slight shift in seasonal streamflow of up to 2 months(for2024-2048)in line with the projected increase in precipitation from May to September.For biomass production,the extreme climate model(RCA)and severe emis sion scenario(RCP 8.5)predicted a decrease up to 46%.However,in the less extreme and more-correlated(with actual catchment climate conditions)climate models(RACMO and HIRHAM5)and in the less extreme emission scenario(RCP 4.5),biomass production increased(up to 20%),and the growth cycle was slightly reduced.SWAT was proven to be a valuable tool to assess climate change impacts on a eucalypt-dominated catchment and is a suitable decision-support tool for forest managers.

桉木单板背面裂隙率对胶合板性能的影响

为给胶合板生产过程的组坯工艺优化提供理论依据,采用图像处理技术与宏观力学性能试验相结合,分析桉木单板背面裂隙率对胶合板性能的影响,探讨桉木单板背面裂隙率与胶合板性能的相关性。结果表明,不同单板背面裂隙率下,干状、冷水浸泡24 h和热水浸泡3 h胶合板的胶合强度及顺纹静曲强度均差异极显著,横纹静曲强度、横纹弹性模量和顺纹弹性模量均差异不显著。随单板背面裂隙率增大,胶合板在3种条件下的胶合强度、顺纹静曲强度和顺纹弹性模量均呈下降趋势。相关性分析表明,单板背面裂隙率与干状胶合强度、冷水浸泡24 h胶合强度和顺纹静曲强度均呈极显著负相关,与顺纹弹性模量呈显著负相关。单板背面裂隙率对胶合板性能的影响表现为冷水浸泡24 h胶合强度>干状胶合强度>顺纹静曲强度>顺纹弹性模量>热水浸泡3 h胶合强度>横纹弹性模量>横纹静曲强度。

桉树人工林土壤呼吸昼夜变化及其对环境因子的响应

以雷州半岛地区尾叶桉人工林为研究对象,采用LI-8150土壤碳通量测量系统,连续测定其土壤呼吸速率及相关环境因子的昼夜变化规律,分析土壤呼吸的时间变化特征及其对环境因子变化的响应,旨在为桉树人工林生态系统土壤碳排放估算提供数据支持。结果表明:尾叶桉人工林土壤呼吸速率昼夜变化为双峰趋势,最大值和最小值分别在4:00和16:00取得,分别为3.95μmol·m^(-2)·s^(-1)和3.29μmol·m^(-2)·s^(-1),日均值为3.61μmol·m^(-2)·s^(-1)。从昼夜变化来看,土壤呼吸与土壤温度、土壤热通量呈极显著负相关。从月变化来看,土壤呼吸与土壤温、湿度均存在极显著正相关关系。土壤日碳排放量为2.59~4.56 g·m^(-2)。可见,对人工林土壤碳排放进行估算时应考虑不同时间尺度环境因子对土壤呼吸影响的方向和强度。

基于高光谱分析技术的桉树叶片黄化识别

桉树黄化病是一种较特殊的生理性病害,存在一定的突发性和随机性,及时发现并补充养分可大幅减少病害带来的损失。采集桉树黄化叶片、未发病叶片和正常叶片,采用高光谱仪测定不同叶片的光谱特征,基于偏最小二乘法判别分析(Partial Least Squares Discriminant Analysis,PLS-DA)和正交偏最小二乘法判别分析(Orthogonal Partial Least Squares Dis-criminant Analysis,OPLS-DA)方法,分别建立判别分析模型,对比模型判别效果。结果表明,不同叶片光谱反射曲线呈相同趋势,反射率差异明显,差异较大的波段主要为近红外波段800~1260、1400~1720和2000~2400 nm,受病害影响叶片的原始光谱反射率明显高于正常叶片;对数变换可在一定程度上减少光谱数据冗余量,突出差异;两种线性判别分析方法均能识别潜在黄化叶片,Log-OPLS-DA的判别效果更好,模型R2为0.91,RMSE为0.203。高光谱分析技术结合OPLS-DA对桉树黄化叶片具有一定的预测和识别潜力。

不同混交模式下幼龄桉树混交林的生长和水土流失特征研究

设计尾巨桉×红椿和大花序桉×闽楠的垂直、水平、块状三种混交方式的试验林,以研究不同混交模式下桉树混交林的生长和水土流失规律。结果表明:1年生尾巨桉、红椿、大花序桉和闽楠分别在水平、块状、块状和水平混交模式下的树高增长率最大,依次为1560.00%、863.33%、457.50%和6.67%,因此水平混交模式和块状混交模式的林分树高生长效果较好。在尾巨桉×红椿和大花序桉×闽楠两种林分中的月均地表径流以块状混交模式最少,分别是107.72 L和215.24 L,月均土壤流失以块状混交模式较少,分别是4.95 kg和7.25 kg,因此块状混交模式对水土保持的效果较优于垂直混交模式和水平混交模式。综合考虑,采用块状混交模式效果最好。

巨桉(Eucalyptus grandis)人工林土壤动物群落对采伐干扰的初期响应

为了解采伐干扰对巨桉（Eucalyptus grandis）人工林土壤动物的影响,于2005～2007年采用手捡法和干湿漏斗法对四川省洪雅县巨桉人工林采伐干扰前和采伐干扰后土壤动物群落进行调查,采伐干扰前四季共获土壤动物4775头,分属4门11纲27目,采伐干扰后获土壤动物4640头,分属4门10纲23目。采伐干扰后秋季（10月）、冬季（1月）和春季（4月）土壤动物个体数较采伐干扰前分别上升224头、368头和443头,而夏季（7月）下降了1170头。采伐干扰前巨桉人工林土壤动物个体数与类群数季节变化趋势基本一致,而采伐干扰后土壤动物类群数变化受土壤动物个体数变化的影响较小。与采伐干扰前相比,采伐干扰后枯落物层各季节土壤动物密度均低于采伐前,0～5 cm土层土壤动物密度与干扰前呈相反的变化趋势,其波动较5～10 cm和10～15 cm土层大。采伐干扰后土壤动物类群数四季共减少4个,采伐干扰前后土壤动物优势类群类群数波动小,采伐后常见类群类群数上升（除冬季外）,稀有类群对采伐干扰较敏感,其类群数下降幅度较大。采伐干扰前后同功能种团均以杂食性和腐食性土壤动物为主,两者百分比之和均在89%以上。密度-类群指数（DG）和多样性指数（H′）的变化趋势相似,采伐干扰前后的变化趋势相反,表明采伐干扰对巨桉人工林土壤动物季节变化有较大影响。

Sound absorption property of wood for five eucalypt species

The sound absorption coefficients of wood and wood boards for five eucalypt species (Eucalyptus urophylla, Euca-lyptus urophylla E. grandis, Eucalyptus urophylla E. tereticornis, Eucalyptus urophylla E. camaldulensis and Eucalyptus cloeziana) that were collected from plantation in Dongmen Forestry Center of Guangxi Province, China were tested with stand-ing wave method and their sound absorption properties were also compared. The results showed that the sound absorption co-efficients of the five eucalypt wood species did not change evidently below 1000 Hz, but above 1000 Hz their sound absorption coefficients increased with the increasing frequency. The difference in sound absorption coefficient among five species of eucalypt wood is not evident at the tested frequency range (200-2000 Hz), but the sound absorption property of Eucalyptus urophylla at low frequency is better than that of other four species. The sound absorption coefficient of the tangential-sawn board is higher than that of the radial-sawn board. The sound absorption property of eucalypt wood of 0.5 cm in thickness is much better than that of 1.0 cm in thickness. It is concluded that wood sound absorption properties of eucalypts are affected by their board thickness and the type of sawn timber within the testing frequency, but the variance of wood sound absorption property among the five tested species is not significant.

广西13家国有林场桉树资源变化分析

为实现桉树资源高质量发展,根据2003—2020年森林资源调查数据,对广西13家国有林场(高峰、七坡、树木园、东门、派阳山、钦廉、博白、六万、维都、三门江、黄冕、大桂山、雅长)桉树资源变化情况进行分析。结果表明:2003—2020年,桉树人工林面积从57782.4 hm^(2)增加到100126.75 hm^(2),蓄积从1631700 m^(3)增加到8556100 m^(3);单位面积蓄积量从21.66 m^(3)•hm^(−2)上升到85.5 m^(3)•hm^(−2);单位面积年均生长量从6.1 m^(3)•hm^(−2)•年^(−1)上升到24.7 m^(3)•hm^(−2)•年^(−1)。至2020年,在13家林场中场内桉树人工林面积达10000 hm^(2)以上有3家,5000~10000 hm^(2)的有6家,5000 hm^(2)以下的有4家;桉树人工林蓄积量1000000m^(3)以上的有2家,500000~1000000m^(3)的有7家,500000 m^(3)以下的有4家;单位面积蓄积量100 m^(3)•hm^(−2)•年^(−1)以上的有6家,80~100 m^(3)•hm^(−2)•年^(−1)的有3家,80 m^(3)•hm^(−2)•年^(−1)以下的有4家;单位面积年均生长量超过30.0 m^(3)•hm^(−2)的有1家,年均生长量25~30 m^(3)•hm^(−2)•年^(−1)的有4家,年均生长量20~24.9 m^(3)•hm^(−2)•年^(−1)的有6家,年均生长量小于20.0 m^(3)•hm^(−2)•年^(−1)的有2家。针对当前桉树资源经营管理中存在的突出问题,提出加强抚育管理、科学合理调整主伐年龄、加强自然灾害防控等建议。

雷州半岛桉树无性系生态调节服务价值核算

以雷州半岛4种桉树无性系作为研究对象,采用分布式测算评估体系方法从4个功能8个指标系统评估桉树不同无性系调节服务价值并对森林生态系统当期所提供的服务流量进行核算,以期为当地森林生态价值的实现提供一定参考。结果表明:2023年雷州半岛桉树不同无性系调节服务总价值为3.32×10^(9)元·年^(-1)。涵养水源、固碳释氧、净化大气环境、森林防护价值分别为1.22×10^(9)、1.93×10^(9)、1.16×10^(8)、5.79×10^(7)元·年^(-1),分别占比为36.80%、57.95%、3.50%、1.75%,固碳释氧及涵养水源价值是雷州半岛桉树不同无性系调节服务的主要价值。尾细桉、尾巨桉、尾叶桉、巨尾桉调节服务价值量分别为2.30×10^(9)、8.35×10^(8)、9.23×10^(7)、9.27×10^(7)元·年^(-1),分别占比为69.31%、25.13%、2.78%、2.79%。

免炼山免挖穴简力定植对桉树人工林根系和生长的影响

传统的炼山、大穴造林方式易引桉树人工林起水土流失、地力下降等一系列问题,免炼山、免挖穴、简力定植可能是解决上述问题的重要手段。文章以尾巨桉为研究对象,布置了桉树免炼山、免挖穴、简力定植方式并以大穴造林为对照,探讨两种方式对桉树人工林根系与蓄积量的影响。结果表明:造林5年后两种造林方式桉树人工林的根系主要分布范围在土层0~70 cm且根系数量多分布于土层20~50 cm,两种造林方式间差异不显著。造林后前2年,简力定植区的桉树胸径、树高与蓄积量略低于对照区但差异不显著;造林3年后逐渐反超,至第五年简力定植区桉树胸径、树高、蓄积量相较于对照区分别增长4.90%、5.13%、15.00%。简力定植造林未对林木蓄积量产生不良影响,反而提高了林木的生长量,对解决桉树人工林地力下降等问题具有较好的效果。

中国桉树感病叶片球腔菌科和畸腔菌科真菌物种多样性研究进展

球腔菌科(Mycosphaerellaceae)和畸腔菌科(Teratosphaeriaceae)真菌物种占从桉树感病叶片上分离到的至少382个真菌物种的44%以上。文章介绍了全球桉树感病叶片上球腔菌科和畸腔菌科真菌物种多样性特征;阐明了分子数据对球腔菌科和畸腔菌科真菌分类的重要性;总结了分离于中国桉树感病叶片上基于分子数据鉴定的球腔菌科和畸腔菌科真菌各个物种的形态特征和分子鉴定等情况;概述了球腔菌科和畸腔菌科真菌物种的鉴定方法和在桉树上的致病力测试方法。

桂南桉树人工林土壤肥力质量评价及限制因子诊断

为给桉树(Eucalyptus spp.)人工林管理提供理论依据,基于15个土壤化学性质指标,采用主成分分析法构建最小数据集,计算土壤肥力质量综合指数,对桂南4个不同代次5种林龄尾叶桉(Eucalyptus urophylla)人工林土壤质量进行评价;采用限制因子诊断模型,筛选土壤限制因子。结果表明,桉树人工林土壤偏酸性。随桉树人工林代次和林龄变化,土壤有机质、全氮、全磷、全钾、水解氮、有效磷、速效钾、速效钙、速效镁、速效铁、速效锰、速效铜、速效锌和速效硼含量均变异大;土壤pH值变异小。土壤pH值及有机质、全氮、水解氮、有效磷、速效镁和速效硼含量可作为反映桉树人工林土壤肥力质量的最小数据集指标。不同代次和林龄桉树人工林土壤肥力质量好、较好、中等、较差和差等级占比分别为0%、5%、80%、15%和0%。土壤有机质、全氮、全钾、速效铁和速效硼含量是桂南桉树人工林土壤肥力质量的主要限制因子。建议重视有机和无机复合肥的施用,补充铁和硼等微量元素,根据不同代次和林龄实施相应的经营策略。

不同连栽代次桉树人工林土壤团聚体碳、氮和磷化学计量特征

为探讨不同连栽代次对桉树(Eucalyptus spp.)人工林土壤团聚体和土壤化学计量特征的影响,以广西第1~3代连栽桉树人工林为研究对象,分析0~20和20~40 cm土层的土壤团聚体分布特征、稳定性及有机碳(SOC)、全氮(TN)和全磷(TP)含量、储量和其化学计量特征。结果表明,不同连栽代次桉树人工林中,>2 mm粒径土壤团聚体质量百分含量均最高,0.25~1和<0.25 mm粒径土壤团聚体SOC、TN和TP含量均较高,>2 mm粒径土壤团聚体SOC、TN和TP储量均最高。在0~20和20~40 cm土层中,随连栽代次增加,>2和>1~2 mm粒径土壤团聚体质量百分含量均降低,0.25~1和<0.25 mm粒径土壤团聚体质量百分含量均升高;土壤团聚体MWD和GMD均降低,D升高;全土和不同粒径土壤团聚体SOC、TN和TP含量均降低,全土SOC、TN和TP储量均降低;>2、>1~2和0.25~1粒径土壤团聚体SOC、TN和TP储量大多呈下降趋势,<0.25 mm粒径土壤团聚体SOC、TN和TP储量均呈上升趋势。桉树人工林土壤C分解和矿化速率较快,土壤P有效性较高,土壤受N限制。RDA和PLS-SEM结果显示,土壤团聚体稳定性特征对土壤团聚体SOC、TN和TP储量的正面影响最大,连栽代次对土壤团聚体SOC、TN和TP储量的负面影响最大。

Decline of eucalypt trees in tablelands of New South Wales, Australia

Eucalyptus species are the native and major plant group in Australian landscapes. Since European settlement, eucalypt trees heavily decline in the tablelands .of New South Wales. Tree recruitment bog down and the landscape ecosystem hardly recovers to the original state. This paper introduces the history of eucalypt trees and native shrubs decline, analyzes reasons of seedling recruitment decrease in this region, such as clearing, grazing, fire, competition from exotic species, dieback, insects, drought and so on, and summarizes the probable conditions of eucalypt tree recruitment, such as suitable conditions of seedling survival, sufficient seed supply, keep from predation, suitable germination conditions, non-grazed environment, mechanical treatment, weed control, fire regime, disease control etc, lending suggests how to preserve and encourage eucalypt trees recruitment in the area.

Age trends and correlations of growth and wood properties in clone of Eucalyptus urophylla × E. grandis in Guangdong, China

We assessed growth traits and wood properties ofDH32-29, a clone of Eucalyptus urophylla x E. grandis, at age of two to six years in Guangdong in China. Analysis of variance of studied traits showed that there were significant differences （1% level） on all studied traits among ages except for wood basic density. Analysis of age trends of growth traits and wood properties revealed that rotation length of DH32-29 should be more than six years or longer. Phenotypic correlations among traits at individual ages indicated that correlations between growth traits were strongly positive. There was significant change in relationship between growth and wood basic density with increasing age, ranging from -0.03 to -0.54 at 2 and 5 year and 0.003 to 0.3 at 3, 4 and 6 year. Correlations between Pilodyn pin penetration and basic density measured on increment cores showed that Pilodyn could rank or group genotypes or sites into density classes, but failure to predict individual tree and individual clone.

Growth rates of Eucalyptus and other Australian native tree species derived from seven decades of growth monitoring

There is widespread interest in estimating and forecasting individual tree and forest growth rates for restoration and carbon sequestration objectives. Outside intensively managed forests, past attempts have been limited by the lack of accurate long-term monitoring in multi-age mixed native forests to provide estimates of both expected mean diameter increments and the statistical variation in those estimates. A dataset from Eucalyptus-dominated native forests in subtropical Queensland, Australia offers an opportunity to provide accurate estimates of tree and forest growth rates. Over 86,400 trees from 155 native species were identified and remeasured between 1936 and 2011 in 641 permanent sample plots across a 500-2000 mm mean annual rainfall gradient. Individual tree diameter at breast height （DBH） increments observed for all species ranged mainly from 0.01 to 0.5 cm yr-1 （94 % of values）, with consistentdifferences between rainfall zones （mean of 500- 2000 mm yr-1）, and varying differences between species （155） and stem diameter class （10-100 cm）. For some spe- cies, diameter increment increased progressively with rain- fall （e.g. Eucalyptus siderophloia, Eucalyptus propinqua, and Lophostemon confertus）, but in others （e.g. Corymbia citriodora subsp, variegata, Corymbia intermedia, and Eucalyptus biturbinata） the greatest diameter increments were recorded between 1200 and 1600 mm yr-1. Where there were sufficient data, most species exhibited a quadratic relationship between DBH increment and DBH class, but two species （ Callitris glaucophylla and Eucalyptus crebra） native to the 500-800 mm annual rainfall zone showed lin- ear increases in DBH increment with increasing DBH. Continued monitoring of these plots would add to their already great value.

Age Trends and Correlations of Fiber Traits in Clone of Eucalyptus Urophylla×E.Grandis in Guangdong Province

Growth traits and wood properties were assessed for DH32-29,a clone of Eucalyptus urophylla×E.grandis,at the age of two to six in Guangdong,China.Analysis of variance of studied traits showed that there were significant differences(1%level)on Fiber Length and Fiber Width among ages,with F value ranging from 12.73 to 18.91,indicating clear differences between ages.The Fiber Length increased from 0.58 mm at 2-year to 0.60 mm at 3-year,061 mm at 4-year,0.72 mm at 5-year and 0.79 mm at 6-year,meanwhile the annual Fiber Length increment among ages increased from 0.02 to 0.01,0.11 and 0.07 mm,respectively.However,Mean Curl,Kink Index and Kink Angle were not found any trend by age.In general,the correlations between same traits were different with different ages.The biggest negative correlations(-0.78)was found between Fiber Length and Fine Percentage at 4-year while the biggest positive correlations(0.98)was found between Kink Index and Kink Angle at 2-year and 4-year.

Longitudinal growth strains in five clones of Eucalyptus tereticornis Sm

We studied the variability in longitudinal growth strains and wood basic density in five-year old trees from five clones （one tree per clone） of Eucalyptus tereticornis. Mean longitudinal growth strain in clones ranged from 466 to 876 μm. There was a significant difference between clones in growth strains and wood basic density. Clone 10 exhibited maximum growth strains and basic density, whereas clone 3 and clone 7 exhibited minimum growth strains and basic density, respectively. Within a tree, the growth strain variation with tree height was high but statistically insignificant while within tree variation in basic density was very small. There was no specific trend in variation in either strain or density within a tree. There was 5% 200% difference in growth strain on opposite sides of the logs. However two strains showed a strong positive correlation. There was a moderate positive association of wood basic density and mean growth strains in logs. The variation around the periphery emphasize the need to measure strain more than one, preferably on opposite sides at the same height, on a tree to know the mean strain level for the purpose of selection of clones.

Axial variations in anatomical properties and basic density of Eucalypt urograndis hybrid(Eucalyptus grandis × E. urophylla)clones

We studied two clones of Eucalypt urograndis hybrid （Eucalyptus grandis × E. urophylla）, GR283 and GR330, grown in Tumkur district of Kamataka （India）, and felled 5-6 years old three trees of each clone. We recorded axial variations in heartwood content, bark properties, wood density and anatomical characteristics of wood in- cluding fibre length, fibre diameter, fibre wall thickness, lumen diameter, vessel frequency, vessel diameter and vessel element length. Clone GR283 had about 10 % heartwood, significantly lower than for clone GR330 （37 %）. Basic wood density along the tree height varied significantly within and between the clones. We observed significant variations in fibre length, fibre diameter and wall thickness within and between the two clones. Vessel frequency and vessel element length did not vary but vessel diameter differed significantly between the clones. With a greater proportion of sapwood, clone GR283 can be uti- lized for paper and pulp applications. Clone GR330 had a higher proportion of heartwood and lower wood density and, hence, is more suitable for light-weight material applications.

Elevated CO2 offsets the alteration of foliar chemicals(n-icosane,geranyl acetate,and elixene)induced by elevated O3 in three taxa of O3-tolerant eucalypts

Eucalypts are important forest resources in southwestern China,and may be tolerant to elevated ground-level ozone(O3)concentrations that can negatively affect plant growth.High CO2 may offset O3-induced effects by providing excess carbon to produce secondary metabolites or by inducing stomatal closure.Here,the effects of elevated CO2 and O3 on leaf secondary metabolites and other defense chemicals were studied by exposing seedlings of Eucalyptus globulus,E.grandis,and E.camaldulensis×E.deglupta to a factorial combination of two levels of O3(<10 nmol mol^(−1)and 60 nmol mol^(−1))and CO2(ambient:370μmol mol^(−1)and 600μmol mol^(−1))in open-top field chambers.GC-profiles of leaf extracts illustrated the effect of elevated O3 and the countering effect of high CO2 on compounds in leaf epicuticular wax and essential oils,i.e.,n-icosane,geranyl acetate and elixene,compounds known as a first-line defense against insect herbivores.n-Icosane may be involved in tolerance mechanisms of E.grandis and the hybrid,while geranyl acetate and elixene in the tolerance of E.globulus.Elevated O3 and CO2,singly or in combination,affected only leaf physiology but not biomass of various organs.Elevated CO2 impacted several leaf traits,including stomatal conductance,leaf mass per area,carbon,lignin,n-icosane,geranyl acetate and elixene.Limited effects of elevated O3 on leaf physiology(nitrogen,n-icosane,geranyl acetate,elixene)were commonly offset by elevated CO2.We conclude that E.globulus,E.grandis and the hybrid were tolerant to these O3 and CO2 treatments,and n-icosane,geranyl acetate and elixene may be major players in tolerance mechanisms of the tested species.