黄波罗育苗中混雪层积时间及保留密度研究

对辽宁东部山区黄波罗播种育苗的混雪层积时间和保留密度进行了研究。结果表明:随混雪层积时间增加,黄波罗种子发芽率和出苗率呈上升趋势,混雪层积145d的发芽率和出苗率最大,分别达到81.35%、64.59%;1年生幼苗保留密度为100株·m-2时,Ⅰ级苗单位产量达到最高。     

杉木、拟赤杨混交对杉木持续生长的影响

杉木 [Cunninghamia lanceolata (Lamb.) Hook.]是我国南方主要造林树种之一 ,但近 2 0a来因不合理的栽培制度如炼山、大面积纯林经营、连栽等导致森林生态环境的恶化、地力衰退、林分稳定性下降 ,严重影响杉木人工林的持续经营[1 ,2 ] 。在认识树种生物学特性的基础上 ,通过运用人为措施促进自然趋同 ,有意识、有目的地营造针阔混交林 ,可形成具有地带性群落特点的稳定性强、产量高的人工林 [3,4]。近来南方各地开始大力营造杉阔混交林 ,并开展混交林林分结构和生产力及混交改善微生态环境等相关研究 ,取得了显著成效 [5～ 9] 。本文选择…     

依兰国营林场不同林分结构内柞树生长状况差异及技术对策的研究

通过"样方标准地调查法"研究了依兰国营林场不同林分结构内柞树的生长状况,通过方差分析和多重比较方法得到柞树在针阔混交林、阔叶混交林和柞树纯林中的生长状况排序。结果表明:针阔混交林内柞树的胸径年均生长量、树高年均生长量和材积年均生长量3项指标在18~42 a之间均明显高于阔叶混交林内柞树和柞树纯林,优势明显。所以,无论从生态角度还是用材角度,培育混交异龄复层林结构对森林的永续经营和利用具有重要的作用。     

落叶松与水曲柳混交林的营造

通过对落叶松与水曲柳生物生态学特性 ,以及选择混交树种的条件和依据的论述 ,说明了营造落叶松与水曲柳混交林的可行性     

半固定沙地樟子松小叶锦鸡儿混交林营造及经营技术研究

在对嫩江沙地樟子松和小叶锦鸡儿人工混交林林分状况和生长指标调查的基础上,采用统计分析方法,探讨了混交林主辅林种间的生长消长关系,结果表明:随着林龄的增长,辅助树种小叶锦鸡儿对主栽树种樟子松的生长发育具有抑制作用,樟子松的生长发育进程减慢,应对小叶锦鸡儿林分进行人工干预,以促进樟子松的生长发育。     

长白山典型阔叶红松林土壤二氧化碳排放通量

随着大气CO2浓度的升高,主要由其引起的温室效应与对生物新陈代谢的影响变得越来越显著。森林生态系统在全球碳循环中扮演着重要的角色。为了评估和理解森林土壤CO2通量及其随空气和土壤温度的季节和昼夜变化规律,我们在长白山北坡典型阔叶红松林内利用静态箱技术进行了原位观测。实验在整个生长季(6月初至9月末)昼夜进行,利用气相色谱进行气体分析。结果表明: 长白山阔叶红松林土壤是大气二氧化碳源,其CO2通量具有明显的季节和昼夜变化规律。通量的变化范围是(0.30-2.42)μmol穖-2穝-1,平均值为0.98μmol穖-2穝-1。土壤CO2排放的季节规律表明,土壤CO2通量的变化与气温和土壤温度的变化有关。CO2平均通量的最大值出现在7月((1.27±23%)μmol穖-2穝-1),最小值出现在9月((0.5±28%)μmol穖-2穝-1)。土壤CO2的昼夜波动与土壤温度变化有关,而在时间上滞后于温度的变化。森林下垫面土壤CO2通量与土壤温度显著相关,与6cm深度土层温度相关系数最大。基于气温和土壤温度计算的Q10值范围为2.09-3.40。图2表3参37。     

福建柏与萌芽杉木混交林经营效果的调查研究

安溪半林林场在杉木迹地上营造福建柏,并选留杉木萌芽条形成福建柏杉木混交林,不论混交林经营密度大小,福建柏生长均比纯林好。大、中密度组的福建柏生长比萌芽杉木快,但在小密度组则相反。萌芽杉木在大、中密度条件下,生长不如同龄纯林,在小密度条件下的平均树高、胸径是纯林的140.2%和148.2%。说明福建柏与萌芽杉木混交培育方式是成功的,但到15年生以后,经营密度以1 500株.hm-2左右,混交比例6∶4为宜。     

Drivers of Setaria pumila (Poir.) Roem. et Schult growth and impact on forage quality in lowland Switzerland meadows

Invasive grasses (especially Setaria pumila (Poir.) Roem. et Schult) increasingly threaten meadows and pastures as a consequence of human impact and climate change. We conducted a study in 2012 and in 2013 to better understand the growing cycle and the influence of S. pumila on forage quality of lowland meadows. We observed a rapid increase of S. pumila presence and phytomass on the southern side of the Alps across the growing season. We measured (i) above‐ground phytomass, with a modified Corral‐Fenlon method; (ii) botanical composition using the linear point quadrat method; and (iii) grassland chemical composition by NIRs (near‐infrared spectroscopy) analyses. To test the hypothesis that S. pumila summer growth is related to specific climatic conditions, meteorological data (temperature, precipitation and evapotranspiration) were collected from meteorological stations near the study sites. Total phytomass was sorted into S. pumila and other species. We used a generalized linear mixed models (GLMM) and found the abundance of S. pumila to be inversely correlated with rainfall and the presence of other species, but positively correlated with temperature increase. The increase of S. pumila above‐ground phytomass production was linked to a reduction of forage quality.     

Effects of formic acid and potassium diformate on the fermentation quality,chemical composition and aerobic stability of alfalfa silage

The objective of this study was to evaluate the efficacy of potassium diformate (KDF) as a potential additive for alfalfa silage. Fresh alfalfa was untreated or treated with formic acid (4 g/kg fresh weight, FW) or three concentrations of KDF (4, 5.5 or 7 g/kg FW). After 60 days of ensiling, the addition of formic acid and greater levels of KDF (5.5 and 7 g/kg) effectively reduced silage pH and inhibited the undesirable bacteria, indicated by lower butyric acid, ethanol, ammonia N concentrations and microbial populations (including enterobacteria, yeasts, moulds and clostridia). Additives decreased the dry‐matter loss, and more water‐soluble carbohydrates were preserved in the silages with formic acid or potassium diformate than in the control. Alfalfa silages treated with formic acid at 4 g/kg FW or potassium diformate at 5.5 or 7 g/kg FW were classified as the highest quality silage based on the higher Flieg's point (above 70) and remained stable for more than 9 days during aerobic exposure. Potassium diformate is recommended as an effective additive for alfalfa silages at a level of 5.5 or 7 g/kg FW under the humid and hot conditions of southern China.     

Mixed cropping with ice plant alleviates the damage and the growth of cowpea under consecutive NaCl treatment and after the recovery from high salinity

We investigated the alleviative effects of mixed cropping using ice plant, which is one of the salt-accumulating halophytes, on the damage and growth inhibition of cowpea, which is not tolerant to high salinity. Three cropping patterns (mono cropping of cowpea and ice plant and their combination) were tested. The plants were treated with 0, 100, 200 and 300 mM NaCl for 14 days (consecutive NaCl). The plants were also treated with NaCl for 3 days, followed by 2 weeks (short-term recovery) and 1 month (long-term recovery) recovery. Salinity levels for short-term recovery were similar to those of the consecutive experiment, while the concentration of long-term recovery was 250 mM. The alleviative effects of mixed cropping in the consecutive NaCl experiment were observed at 200 and 300 mM NaCl. Mixed cropping significantly reduced the Na content in the cowpea leaves at 200 and 300 mM NaCl compared with mono cropping. In addition, the Na content in the soil of mix-cropped cowpea at 200 and 300 mM NaCl was statistically lower than that of the mono cropping. Mixed cropping was effective to recover from high concentration of NaCl in the experiments of short- and long-term recovery. These results indicate that mixed cropping with a halophyte could be effective in mitigating the damage and growth inhibition of a glycophyte not only under salinity but also under recovery periods.