华北山区非主要生长季典型人工林土壤呼吸变化特征

2005年11月至2006年3月,利用Li-8100土壤呼吸自动观测系统及AR-A-ECH土壤温度湿度自动观测系统,观测了华北山区30年生侧柏和25年生栓皮栎林土壤呼吸速率与土壤温度及湿度,分析了非主要生长季土壤呼吸变化特征.结果表明:(1)晴或多云条件下,2种人工林林地土壤呼吸速率都明显高于阴天,但日变化均不明显;整个非主要生长季,土壤呼吸速率(SRR)呈现出明显的日际变化特征;2005年11月至2006年1月,SRR呈显著降低的趋势,在2月份,维持在相对较低水平,进入3月中旬则迅速回升,降雪使SRR均有不同程度的增加;整个非主要生长季,侧柏林地与栓皮栎林地的平均SRR分别为0.61、0.39μmol·m-2·s-1.(2)2种人工林林地地表及地下5、10、15、20 cm深处土壤温度与SRR都存在显著的指数相关关系(p《0.01),且5cm深处的土壤温度与SRR的相关性最好,侧柏和栓皮栎在该深处的Q10值分别是2.280和1.602;侧柏、栓皮栎林地SRR与土壤含水量分别呈显著的线性相关关系、多项式相关关系(P《0.01).这2种人工林林地SRR与5cm深处的土壤温度和土壤含水量均有很好的复相关关系(P《0.01),且比较偏相关系数表明:影响2种林地土壤呼吸速率的最主要土壤环境因子都是土壤温度.     

滩地美洲黑杨人工林皆伐对地表甲烷通量的短期影响

2011年4-7月,利用静态箱-快速甲烷分析仪(FMA)法,在岳阳市君山区长江外滩美洲黑杨人工成熟林对比观测皆伐区和未采伐区地表甲烷通量,结合同步观测的土壤温度、湿度和植被结构因子,分析皆伐对试验区地表甲烷汇功能影响的原因.结果表明:滩地美洲黑杨人工林土壤在未遭遇水淹年份(2011)生长旺季为甲烷的汇;2次观测显示,皆伐区的甲烷吸收速率均显著(P＜0.001和P＜0.05)低于未采伐区,分别仅为未采伐区的29％和22％,且皆伐改变了甲烷通量的日变化规律;皆伐导致土壤温度、湿度和植被结构等环境因子发生的变化共同导致了皆伐区甲烷汇功能的显著下降.     

利用气温进行统计回归预测土温

在安吉县毛竹林通量观测塔采集了2011年3月21日至2012年7月21日连续观测得到的5、50和100 cm深度土壤温度和38、7、1 m高度大气温度数据,分析土壤温度和空气温度之间的数学模型来预测土壤温度。结果表明:不同层次土壤温度和空气温度的变化趋势都呈现出大致相同的变化趋势,随着土壤深度的增加,影响因素增加,土温与气温的最高峰相比存在滞后期,相关性分析显示5 cm土温和各层气温基本一致,50 cm处的土壤最高温度比1 m最高气温向后推移15 d;100 cm的土壤温度最高峰比1 m气温最高峰推移28 d。     

生态垫流动沙地应用试验

为了防治沙漠化,减少流动沙丘为害,该文对生态垫治理流动沙丘技术进行了研究,为生态垫治理流动沙丘提供理论依据。通过与裸沙地进行对比研究,调查观测了生态垫覆盖对流动沙丘土壤温度、土壤含水量、固沙植物生长情况的影响情况,研究显示：流动沙丘铺设生态垫能明显降低浅层土壤温度,避免地表及地面以下5、10、15cm处土壤温度剧烈波动...     

森林小气候观测方法(三)

六、观测的时间森林小气候观测的时间一般可与气象台站观测的时间相同(每日2、8、14、20时观测),但是为了获得气象要素日变化的规律,有时也需要在不同的天气类型(晴天、阴天、昙天)下作短时期的间隔1或2小时的全日观测,鉴于各气象要素都具有昼间变化大,夜间变化小的特征,在做全日观测时,有时也可以使观测的时间间隔,昼间较短而夜间较长。不过为了与气象台站比较起见,在任何情况下都最好能把2、8、14、20时4个时间包括在内。但由于森林小气候观测的条件所限。不     

华北石质山区刺槐人工林的土壤呼吸

2006年1-12月,利用Li-8100土壤呼吸自动观测系统及AR5土壤温度湿度自动观测系统观测土壤呼吸速率、土壤温度及湿度,分析华北石质山区35年生刺槐林土壤呼吸速率时间变化规律及其影响机制.结果表明:1)刺槐林土壤呼吸速率日内变化特征不明显,但日际及季节变化明显,全年呈现出单峰变化趋势,且与土壤温度的日际及季节变化趋势基本一致.具体表现为: 1-3月土壤呼吸速率较低,日际变化略有波动,从4月开始逐渐上升 ,直至7月达到最大值,而后开始逐渐下降,直至11月约降低至1-3月时的水平,并保持到1 2月.全年土壤呼吸速率平均值为2.50 μmol·m-2s-1,主要生长季(4-10月 )土壤呼吸速率明显高于非主要生长季(1、2、11及12月),二者分别为3.63与0.90 μmo l·m-2s-1 .2) 刺槐林地土壤呼吸速率与表层0 cm、地下5、10、15和20 cm 深度处土壤温度都存在极显著的指数相关关系(p<0.01),且与土深20 cm处温度的相关性最好.上述不同深度处的Q10值分别是2.20、2.28、2.34、2.40和2.48. 3)刺槐林地土壤含水量与土壤呼吸速率的相关关系不明显.     

林火气象站的观测与建立技术

林火气象站提供的气象数据是森林火灾预防和控制的一个重要信息来源.我国气象台站数量和密度较低,远离林区的气象台站所测定的气象因子数值与林区的气象因子数值有较大出入,难以满足森林火灾预防和扑救的需求.林火气象站的观测和建立需要一定的专业知识,本文简要的介绍林火气象站的发展,以及气象观测场的选择、林火自动气象站的原理和安装等.     

樟子松沙丘阳坡造林试验研究初报

本文通过樟子松苗木深栽、摘心苗、地膜覆盖和容器苗造林试验以及对土壤温度和含水量的观测,总结出樟子松沙丘阳坡造林的4种方法及差异,在坝上干旱沙丘地带有广阔的推广前景。     

采伐强度对小兴安岭低质林分土壤碳通量的影响

针对择伐后的小兴安岭低质林分,采用LI-8100碳通量自动监测系统在春、夏、秋、冬4个季节对低质林分土壤碳通量进行观测,运用统计分析方法,分析采伐强度对土壤碳通量、土壤温度与湿度的影响。结果表明:采伐区的土壤碳通量高于对照区,随采伐强度的增加土壤碳通量呈现波动性,从采伐强度22%～47%,碳通量逐渐减小,之后趋于平稳,春、夏、秋、冬4个季节土壤碳通量的最大值出现在低度和中度采伐强度林分条件下;随采伐强度增加土壤温度增加,土壤湿度减少,土壤碳通量与距地表10cm处的土壤温度的关系符合指数模型,土壤碳通量与土壤湿度的关系符合一元二次模型;从标准化回归方程看出,土壤碳通量主要由土壤温度与湿度共同影响,且土壤湿度对碳通量的影响大于土壤温度的影响。采伐强度与土壤碳通量具有负相关性,二者的关系为双曲线。     

流溪河国家森林公园旅游气候研究

采用短期定位观测与气象台站资料分析相结合的方法，对流溪河国家森林公园主要景点的地形小气候、森林小气候和水域小气候进行了观测和对比，分析了不同海拔高度处的气候特点与候温季节．结果表明，该森林公园具有典型的亚热带湿润季风山地气候特征，四季分明，气温垂直变化大，山上夏季凉爽，宜避暑消夏；山下冬季温暖，宜避寒度假；山地森林小气候优越，具开展旅游活动的气候优势．建议加强森林保护，优化林分结构，以进一步提高其涵养水源和卫生保健功能．     

温度对越南黄花梨种子萌发的影响

正温度是影响种子萌发的主要因素,也是决定种子萌发速度的首要条件,适宜的发芽温度是种子萌发所必需的环境条件之一,摸清种子萌发的适宜温度对指导农林业苗木生产实践具有重要意义[1-2]。不同植物的种子由于习性、生境和生理生态学等方面的差异,其最适的发芽温度差异较大[3-5]。越南黄花梨(Dalbergia tonkinensis Prain),越南名"su'a",又名越南黄檀、通京黄檀、越南香枝木等[6-7],是蝶形花科黄檀属的一种速生落叶乔     

不同温度处理对‘绿世界’卡特兰花芽分化及内源激素动态变化的影响

运用酶联免疫法,测定了卡特兰在花芽分化期经3种不同温度处理其新叶内源激素的动态变化,结果表明:(1)25 ℃/20 ℃处理能显著促进花芽分化,30 ℃/25 ℃处理花芽能正常分化,35 ℃/30 ℃处理抑制花芽分化;(2)25 ℃/20 ℃、30 ℃/25 ℃处理的新生叶片中赤霉素(GA₃)、玉米素(ZR)、脱落酸(ABA)含量增加,吲哚乙酸(IAA)含量减少;35 ℃/30 ℃处理抑制新生叶片中GA₃、ZR、ABA含量,促进IAA含量,而较低的GA₃、ZR、ABA含量和较高水平的IAA含量不利于花芽分化;(3)35 ℃/30 ℃处理使GA₃/IAA、GA₃/ZR的比值处于一个较为稳定的状态,而这种状态不利于花芽分化。保持较低的IAA/ZR与IAA/ABA水平,有利花芽分化的继续进行。     

Suckering response of aspen to traffic-induced-root wounding and the barrier-effect of log storage

In a growth chamber, we tested how the seasonal timing of placing a physical barrier (simulating a possible effect of log storage) and inflicting root damage impacted aspen (Populus tremuloides Michx.) root systems and their suckering capability. Roots from 4-year-old saplings were used, and one half of these root systems had the above-ground portion cut in the winter (dormant) while the other half was cut during the growing season in the summer. Damage was inflicted to the roots by driving a large farm tractor over them, and a covering treatment was applied using a polystyrene board to prevent suckers from emerging from the soil. Soil temperatures for the winter-cut root systems were kept at 5 °C over the growing season, using a water bath, while for the summer-cut root systems soil temperatures were maintained at 17 °C over the growing season. In the winter-cut root systems, both log storage and root wounding caused a 40% reduction in living root mass and carbohydrate reserves, as well as reducing sucker numbers and their growth performance. In the summer-cut root systems log storage and root wounding reduced living root mass by approximately 35% as well as sucker growth, but had less of an impact on the number of suckers produced.     

杜鹃红山茶CaAPX基因的克隆、表达及功能分析

[目的]利用分子生物学技术探讨杜鹃红山茶CaAPX基因的表达模式及在模式植物烟草中所起的抗寒、耐热作用,为今后山茶花抗逆育种奠定基础。[方法]根据山茶花同源序列设计特异性引物,利用同源克隆和3’,5’-RACE技术,从杜鹃红山茶嫩叶组织中克隆出抗坏血酸过氧化物酶(APX),命名为CaAPX,基因全长1 097 bp,开放阅读框753 bp,编码250个氨基酸。实时荧光定量PCR对杜鹃红山茶7种组织和温度胁迫下该基因的表达模式进行分析。[结果]表明:CaAPX基因在杜鹃红山茶7种组织中均得到表达,但表达水平不一,表达量由高到低依次为:未成熟果实嫩叶花苞叶芽种胚花瓣花芽,其中,未成熟果实中的表达量是其它组织的2.6811.44倍;温度胁迫处理8 h后该基因呈上调表达,CaAPX基因表达量分别是0 h的3.49和2.67倍。CaAPX基因转化烟草分析表明,过量表达CaAPX基因后,APX活性提高了2.58 4.09倍,抗坏血酸(As A)含量提高了2.673.56倍,并且转基因烟草植株的抗寒、耐热能力也获得提高。[结论]通过过量表达CaAPX基因能够提高烟草植株的抗寒、耐热性,为山茶花抗逆育种提供了科学依据。     

温度和处理方式对余甘子果理化性质影响

余甘子果实采收期长于多数水果,留树越冬落果率低,采后余甘子果实失重率、腐烂率高,容易发生褐变,所以果实的贮藏保鲜成为了余甘子加工行业的关键问题,试验选取包装、预处理方式以及贮藏温度对采后余甘子果进行贮藏工艺的研究。结果表明:冷激处理并且真空包装,贮藏温度为4℃条件下,余甘子果实的失重率为0,含水率保持在81.5%左右,贮藏时间达到70 d,理化性质变化较小,Vc和还原糖等营养成分得到较好保留,无胀袋现象,为余甘子果的贮藏提供理论参考。     

环境因子对喙尾琵甲卵孵化的影响

研究了温度、光照和基质含水量对喙尾琵甲(Blaps rhynchopetera Fairmaire)卵孵化的影响。结果表明:12 - 28 ℃ 6个恒温条件下卵均可孵化,随着温度的升高卵的发育历期缩短(32.92 - 5.83 d),发育速率加快(0.03 - 0.172/d)。12 - 25 ℃下孵化率较高,平均孵化率70%,8 ℃和31 ℃未见卵孵化。喙尾琵甲卵的发育起点温度为(10.08±0.93) ℃,有效积温为(99.91±8.11)日·度。在0 - 8 000 lx光照条件下,随着光照度的增加,孵化率呈下降趋势,光照度≥8 000 lx,卵不孵化。基质含水量和温度共同影响试验中,基质含水量、温度以及二者的交互作用均对卵的孵化有显著影响,多重比较分析后筛选出了适宜卵孵化的温度含水量组合;并对云南地区限制喙尾琵甲卵孵化的气候因素进行了探讨。     

Soil–atmosphere CO2, CH4 and N2O fluxes in boreal forestry-drained peatlands

Greenhouse gas emissions from managed peatlands are annually reported to the UNFCCC. For the estimation of greenhouse gas (GHG) balances on a country-wide basis, it is necessary to know how soil–atmosphere fluxes are associated with variables that are available for spatial upscaling. We measured momentary soil–atmosphere CO₂ (heterotrophic and total soil respiration), CH₄ and N₂O fluxes at 68 forestry-drained peatland sites in Finland over two growing seasons. We estimated annual CO₂ effluxes for the sites using site-specific temperature regressions and simulations in half-hourly time steps. Annual CH₄ and N₂O fluxes were interpolated from the measurements. We then tested how well climate and site variables derived from forest inventory results and weather statistics could be used to explain between-site variation in the annual fluxes. The estimated annual CO₂ effluxes ranged from 1165 to 4437 g m⁻² year⁻¹ (total soil respiration) and from 534 to 2455 g m⁻² year⁻¹ (heterotrophic soil respiration). Means of 95% confidence intervals were ±12% of total and ±22% of heterotrophic soil respiration. Estimated annual CO₂ efflux was strongly correlated with soil respiration at the reference temperature (10 °C) and with summer mean air temperature. Temperature sensitivity had little effect on the estimated annual fluxes. Models with tree stand stem volume, site type and summer mean air temperature as independent variables explained 56% of total and 57% of heterotrophic annual CO₂ effluxes. Adding summer mean water table depth to the models raised the explanatory power to 66% and 64% respectively. Most of the sites were small CH₄ sinks and N₂O sources. The interpolated annual CH₄ flux (range: −0.97 to 12.50 g m⁻² year⁻¹) was best explained by summer mean water table depth (r² = 64%) and rather weakly by tree stand stem volume (r² = 22%) and mire vegetation cover (r² = 15%). N₂O flux (range: −0.03 to 0.92 g m⁻² year⁻¹) was best explained by peat CN ratio (r² = 35%). Site type explained 13% of annual N₂O flux. We suggest that water table depth should be measured in national land-use inventories for improving the estimation of country-level GHG fluxes for peatlands.     

杨小舟蛾羽化节律及羽化率影响因子分析

通过野外观察和实验室可控条件下的测定,研究了杨小舟蛾蛹的羽化日节律特征和第1 4代羽化进程差异,统计了各代次羽化率和历期,分析了其羽化影响因子。结果表明：杨小舟蛾蛹羽化表现为“驼峰型”节律特征,羽化高峰出现在4：00和17：00;其1 4代蛹在相同羽化条件下羽化进程存在差异,羽化完成总虫数80%所需时间逐渐缩短,相同世代雌雄羽化高峰间隔也逐渐缩短;杨小舟蛾蛹1 4代在相同羽化条件下的平均羽化率间存在显著差异,分别为（31.41±1.16）%、（43.67±1.84）%、（38.20±1.39）%和（27.81±2.42）%;各代羽化历期存在显著差异,分别为（10.71±0.45）、（8.56±0.17）、（6.88±0.68）、（6.43±0.66）d。羽化影响因子分析表明：不同温度和湿度处理间羽化率存在显著差异,较好的组合为光期温度（30±1）℃、暗期温度（24±1）℃,光期湿度（50±10）%、暗期湿度（70±10）%,光周期处理间差异不显著。     

Soil CO2 efflux in an Afromontane forest of Ethiopia as driven by seasonality and tree species

Variability of soil CO₂ efflux strongly depends on soil temperature, soil moisture and plant phenology. Separating the effects of these factors is critical to understand the belowground carbon dynamics of forest ecosystem. In Ethiopia with its unreliable seasonal rainfall, variability of soil CO₂ efflux may be particularly associated with seasonal variation. In this study, soil respiration was measured in nine plots under the canopies of three indigenous trees (Croton macrostachys, Podocarpus falcatus and Prunus africana) growing in an Afromontane forest of south-eastern Ethiopia. Our objectives were to investigate seasonal and diurnal variation in soil CO₂ flux rate as a function of soil temperature and soil moisture, and to investigate the impact of tree species composition on soil respiration. Results showed that soil respiration displayed strong seasonal patterns, being lower during dry periods and higher during wet periods. The dependence of soil respiration on soil moisture under the three tree species explained about 50% of the seasonal variability. The relation followed a Gaussian function, and indicated a decrease in soil respiration at soil volumetric water contents exceeding a threshold of about 30%. Under more moist conditions soil respiration is tentatively limited by low oxygen supply. On a diurnal basis temperature dependency was observed, but not during dry periods when plant and soil microbial activities were restrained by moisture deficiency. Tree species influenced soil respiration, and there was a significant interaction effect of tree species and soil moisture on soil CO₂ efflux variability. During wet (and cloudy) period, when shade tolerant late successional P. falcatus is having a physiological advantage, soil respiration under this tree species exceeded that under the other two species. In contrast, soil CO₂ efflux rates under light demanding pioneer C. macrostachys appeared to be least sensitive to dry (but sunny) conditions. This is probably related to the relatively higher carbon assimilation rates and associated root respiration. We conclude that besides the anticipated changes in precipitation pattern in Ethiopia any anthropogenic disturbance fostering the pioneer species may alter the future ecosystem carbon balance by its impact on soil respiration.     

Changes in light levels and stream temperatures with loss of eastern hemlock (Tsuga canadensis) at a southern Appalachian stream: Implications for brook trout

The exotic invasive insect, hemlock woolly adelgid (Adelges tsugae Annand), is causing mortality in eastern hemlocks (Tsuga canadensis [L.] Carr.) throughout the eastern U.S. Because hemlocks produce dense shade, and are being replaced by hardwood species that produce less shade, their loss may increase understory light levels. In the southern Appalachians, increases in light could increase stream temperatures, threatening species such as brook trout (Salvelinus fontinalis). We studied changes in light and stream temperature with eastern hemlock decline at a headwater southern Appalachian brook trout stream. Our results indicate that stream light levels have increased significantly with adelgid infestation. Leaf-on light levels are currently significantly higher (P < 0.02) in plots containing high basal areas of hemlock (mean global site factor (GSF)(SE) = 0.267(0.01)) compared with plots containing no hemlock (mean GSF(SE) = 0.261(0.01)), suggesting that increases in light have occurred with hemlock decline. The Normalized Difference Vegetation Index (NDVI), a remotely sensed metric of vegetation density, decreased with hemlock decline from 2001 to 2008. In 2001, NDVI showed no relationship (R² = 0.003; F = 0.14; P = 0.71) with hemlock basal area, but by 2008, there was a significant negative relationship (R² = 0.352; F = 19.55; P < 0.001) between NDVI and hemlock basal area. A gap experiment showed that light levels may increase by up to 64.7% more (mean increase in GSF = 27.5%) as hemlocks fall, creating gaps in the canopy. However, stream temperatures did not increase with hemlock decline during the study period, and we found that ground water inputs have a stronger influence on water temperature than light levels at this site. Linear regression showed a significant negative relationship between water temperature and proximity to ground water sources (R² = 0.451; F = 13.14; P = 0.002), but no relationship between water temperature and light levels (R² < 0.02; P > 0.05). In addition, by comparing light levels between plots containing hemlock and those containing only hardwoods, we found that if hemlocks are replaced by hardwoods, light levels under an all-hardwood canopy (mean GSF(SE) = 0.240(0.005)) are unlikely to be higher than they are under the current forest (mean GSF(SE) = 0.254(0.007)). These results suggest that loss of hemlock along southern Appalachian headwater streams could have short-term impacts on light levels, but that long-term changes in light levels, increases in water temperature, and adverse effects on brook trout may be unlikely.