4个树种茎流养分特征研究

对湖南株洲22~25年生的樟树、枫香、杜仲、桂花4个树种树干茎流及林外大气降水中N、P、SiO2、K、Ca、Mg、Cu、Zn和Mn9种养分元素含量进行为期1年测定。结果表明:不同月份大气降水养分元素含量不同,各元素各月平均含量按大小排序为Ca>SiO2>Zn>NH4 -N>K>NO3--N>Fe>Mg>Mn>P>Cu;大气降水经过林冠层后,树干茎流中各养分元素含量变化基本一致,均表现季节动态变化,相对于大气降水,大多数元素含量增加;树种之间的茎流养分特征表现不同,按总含量值排序依次为枫香、杜仲、樟树、桂花;不同养分元素之间的相对含量也表现出较大的差别,养分含量中K、Ca、NH4 -N、SiO2含量最高,NO3--N、Mg、Mn、Zn居中,Fe、P、Cu最低;4个树种共同表现出对Fe、Zn的负淋溶,尤以Zn最显著。     

黑龙江省东部山地白桦人工林对水质的影响

对黑龙江省东部山地白桦人工林生态系统的大气降水、穿透水、树干茎流和地表径流中的pH值、溶解氧、浊度、总溶解固体、电导率、氧化还原电位、K、Na、Ca、Mg、Cu、Zn、Mn和Fe等水质指标进行了测定.结果表明:大气降水经过白桦人工林生态系统后,浊度和总溶解固体值逐渐升高.穿透水除Ca元素外,其他化学元素含量均有不同程度的增加,化学元素含量排序为:K＞ Ca＞ Na＞ Mg＞ Mn＞ Fe ＞Zn＞ Cu.树干茎流中各化学元素含量排序为:K＞Ca＞Mg ＞Na＞Fe ＞Mn ＞Zn ＞Cu.地表径流中各化学元素含量为:K＞ Ca＞ Na＞ Mg＞ Fe＞ Mn＞ Zn＞ Cu.除Na、Ca元素外,大气降水中其他元素的变异系数均较大.穿透水和树干茎流中Cu元素的变异系数大于其他元素,地表径流中Zn元素的变异系数最大.根据淋溶系数的大小排列,穿透水中各化学元素的淋溶序列是:Mn＞K＞Mg＞Fe＞Cu ＞Zn＞ Na＞ Ca.树干茎流中各化学元素的淋溶序列是:K ＞Mn＞ Mg＞ Fe ＞Cu ＞Zn＞ Ca＞ Na.经过淋洗后,穿透水和树干茎流中K和Mg元素增加较多,Ca元素出现负淋溶.     

樟树人工林降水化学性质

对樟树人工林生态系统的大气降水,树干茎流,穿透水中N、P、K、Ca、Mg、Cu、Zn、Mn、和SiO29种养分元素含量进行了测定.结果表明:不同月份大气降水养分元素含量不同,各元素各月平均含量按大小排序为Ca>SiO2>NH4 -N>Zn>K>NO3--N>Mg>Mn>P>Cu;大气降水经过林冠层后,树干茎流、林内穿透水中各养分元素含量变化基本一致,均表现季节动态变化,大多数元素含量增加;树干茎流中各元素含量按大小排序为Ca>K>NH4 -N>SiO2> NO3--N>Mg>Zn>Mn>P>Cu,林内穿透水中各元素含量按大小排序为Ca>K>NH4 -N>SiO2>Zn>NO3--N>Mg>Mn>P>Cu,树干茎流中Cu和Zn为负淋溶.     

长沙市城市森林中湿地松的降水化学性质

对长沙市大气降水和长沙市城市森林中湿地松的树干茎流、穿透水中的N、P、K、Ca、Mg、Cu、Mn和SiO28种养分元素含量进行了测定.结果表明:不同月份大气降水养分元素含量不同,各元素各月平均含量按大小排序为Ca>NH4 -N>K>SiO2>Mg>NO3--N>Cu>P>Mn;树干茎流酸化现象明显,而穿透雨酸化现象不明显;树干茎流中P、Cu为负淋溶.     

枫香人工林林冠截留降水分配及养分特征

采用定位研究方法,根据2007年5月到2008年3月的观测数据,对长沙市天际岭林场枫香人工林生态系统的降水再分配中养分输入进行了研究。结果表明:林外降水、穿透水中以Ca含量最高;树干茎流中NH4+-N的含量最高;NH4+-N、NO3--N、P、Ca、K、Mg、Cu、Mn含量在穿透水和树干茎流中呈上升趋势,其中Mn含量增加幅度最大;Fe、Zn、Cd元素含量在穿透水和树干茎流中呈下降趋势;降水再分配过程中各元素含量随着降水量的增加而降低。     

会同第二代杉木林集水区水质生态效应

对会同第2代杉木林集水区的大气降水、穿透水、树干茎流水、地表水、地下水,集水区旁的小河水、水库水,县城河流水的水质进行了连续5个水文年的定位监测,研究了该集水区水质生态效应.结果表明:集水区地下水、集水区旁小河水、水库水、县城河流水之间的水质无显著性差异;大气降水中各元素含量按高低排列的顺序为K>Zn>Ca>Org-N>NH4-N>NO3-N>Fe>Si>Mg>Mn>P=Cu,穿透水和树干茎流水中,除Zn以外,其余元素的含量均比大气降水中的含量高,地表径流水中K、Ca、Fe、Si元素含量高于穿透水,地下水中NO3-N、P、Mg、Si元素含量高于地表径流水,而NH4-N、Org-N、K、Ca、Fe、Cu、Mn低于地表径流水;大气降水中K、P元素含量变动明显,穿透水和树干茎流水中NH4-N、NO3-N、Org-N、P、K、Cu、、Mn、Si元素含量变动系数均小于大气降水,而Ca、Mg、Zn含量变动系数却大于大气降水;林冠层对大气降水的化学淋溶量按大小依次为Ca>Mg>Fe>K>NH4-N>Mn>NO3-N>P>Cu>Org-N>Zn,Org-N和Zn为负淋溶效应;杉木林生态系统对大气降水中NH4-N、Org-N、K、Cu、Zn、Mn产生有效贮虑效应,其强度依次为Zn>Org-N>NH4-N>Mn>K>Cu>NO3-N,而P、Ca、Mg、Fe元素的贮滤强度为负值.     

长沙市郊枫香人工林降水的化学性质

对长沙市郊枫香人工林大气降水、穿透水、树干茎流中NH4+-N、NO3--N、P、Mg、Ca、K、Cu、Fe、Zn、Mn、Pb等11种化学元素含量进行测定。结果表明:大气降水中化学元素含量变化较大,其加权平均值按大小排序为CaNH4+-NZnNO3--NKMnMgFeCuPb;穿透水、树干茎流中化学元素含量变化不一,但总的趋势是大气降水经过枫香人工林后化学元素含量呈增加趋势,并具有不同程度的季节变化;穿透水、树干茎流中Cu、Fe、Zn普遍呈负淋溶。     

亚热带城市森林中湿地松的降水化学性质变化

对亚热带城市林林中湿地松的大气降水、树干茎流、穿透水中的N、P、K、ca、Mg、Cu、Mn、和SiO_28种养分含量进行了测定。结果表明:该温地松树分的树干茎流总养分含量中,K、Ca、NH_4~ -N、NO_3~-含量最高,SiO_2、Mg、Mn含量居中,P、Cu含量最低。林外降水中各养分元素平均含量排列顺序为NH_4~ -N>K>Ca>SiO_2>NO_3~-N>Mg>P>Cu>Mn,林内穿透水中各元素含量按大小排序为Ca>K>NH_4~ -N>NO_3~--N>SiO_2>Mg>Cu>P>Mn。相对于林外雨,养分均出现富集化,但树干茎流养分富集化高于穿透雨。树干茎流出现强烈的酸化,而穿透雨酸化现象不明显。     

长沙市郊枫香人工林降水的淋溶特征

采用定位研究方法,根据2008—2011年的实验数据,对长沙市郊枫香人工林生态系统的淋溶特征进行了研究。结果表明:在穿透水中,大量元素NH+4-N、NO-3-N、PO-3和SO2-4呈现负淋溶,K、Ca、Mg养分富集现象明显;在树干茎流中,除PO-3外,其它大量元素表现为淋溶增量,养分富集现象较明显。林内降水和树干茎流中Fe、Cu、Zn和Pb等微量元素均呈负淋溶,表现出明显的净化作用,只有重金属元素Mn含量大幅上升,淋溶作用显著,说明枫香对Mn具有较强的富集能力。     

会同广坪林区降雨和杉木林内雨的养分含量

对会同广坪林区的大气降雨、水库水、小河水及杉木林内雨的养分含量进行了5个水文年的定位监测.结果表明水库水、小河水中的10种养分元素N、P、K、Ca、Mg、Fe、Cu、Mn、Zn、Si,有的含量高于降雨,而有的含量低于降雨;降雨中各养分元素按含量高低排列顺序为K＞Zn＞Ca＞Org-N＞NH4-N＞NO3-N＞Si＞Mg＞Mn＞P;林内雨中P、K、Ca、Mg、Fe、Cu、Mn、Zn、Si元素含量均比降雨高;从林冠层淋洗的养分量为79.475 kg*hm-2a-1;从林内雨直接进入林地土壤的养分总量为161.957 kg*hm-2a-1,其中以Ca元素最高,为73.71 kg*hm-2a-1,为外界补充杉木幼林地土壤养分的主要来源,对加速杉木林的养分循环和促进林木生长,具有重要的生态作用.该项研究可为杉木林的持续经营,生态环境保护提供科学依据.     

Armillaria ostoyae in managed coniferous forests in Kastamonu in Turkey

Although several Armillaria species have been reported in Turkey, there is little information about their ecology in Turkish forests. In this study, we investigated five forest stands, approximately 5–74 ha in size, in Kastamonu province in the Black Sea Region of Turkey for the presence of Armillaria species in stumps and logs. The stands were mixed Abies nordmanniana ssp. bornmülleriana and Pinus sylvestris forests managed using a selective cuttings system; the proportion of fir in the total number of stems and stumps ranged from 36 to 98%. Based on sequence analysis of the internal transcribed spacer and intergenic spacer regions of the rDNA, all rhizomorphs sampled from the stumps and logs were of Armillaria ostoyae. The size of the genets was estimated with random amplified microsatellites analysis of the isolates and ranged from single stumps to approximately 450 m². One to seven genets were found in each stand. These results indicate that the genets had arisen from spores and vegetative spread was limited on most sites.     

上海中央公园特大银杏树白蚁防治探讨

通过对上海松江中央公园内65株特大银杏树白蚁为害情况的调查,发现该公园银杏受害率为100%,其中存在活白蚁的银杏占总量的56.9%,采用毒土处理、粉剂疗法、建立白蚁监测点等措施,经过两次灭杀,活白蚁的灭杀率达到92.3%和93.3%,从而使存在活白蚁银杏树的比例从56.9%下降到2.7%,白蚁发生情况明显降低。       

我国食品中农药残留研究进展

随着人们安全健康意识提高,食品中农药残留问题更加受到重视,本文综述了样品预处理研究进展及农药残留快速检测技术研究进展,并简单分析介绍各种方法的优缺点。     

建平半干旱地区石质山地造林技术研究

研究了不同植物在石质山地的造林成活率、土壤化学性质随造林年限的变化和造林措施对土壤化学性质和植物胸径、树高年净生长量的影响。结果表明：不同植物在石质山地的成活率在21%～85%之间,其中白榆和沙打旺的成活率分别为81%和85%,而小叶杨、刺槐、栾树的成活率均在70%左右;植被能明显提高石质山地不同土层的有机质、全N、P2O5含量,但提高程度随土层深度、养分种类和造林年限的不同而不同;在同一土层,生物复合肥料、菌剂和保水剂均显著提高土壤有机质含量（p〈0.01）并显著降低土壤P2O5含量（p〈0.01）;只有保水剂可引起土壤全K含量的明显升高;生物复合肥料、菌剂和保水剂均显著提高白榆、小叶杨、刺槐、栾树树高和胸径的年净生长量,但保水剂的提高程度最高。     

植物DNA甲基化研究进展

植物经常暴露在各种生物和非生物的胁迫之下,这些胁迫会影响植物的生长发育和繁殖并最终导致植物死亡。为了抵御不利的环境条件,植物已经进化出复杂而精细的网络来感知胁迫并激活防御系统。为此,植物激活许多信号转导通路,这些信号转导通路可以改变一些胁迫响应基因的表达,从而引起植物形态、生理和生化的改变以适应逆境。DNA胞嘧啶甲基化是高等真核生物的主要表观遗传机制之一,在维持基因组稳定性和调节基因表达方面起着关键作用。表观遗传变异比遗传变异更为灵活。一旦环境条件发生变化,为了适应新的环境植物都会发生表观遗传的改变。许多研究表明DNA甲基化参与植物的发育和应激反应。基于相关研究对DNA甲基化进行了综述,对植物逆境胁迫有重要意义。     

木材碳封存研究进展

碳封存可以分工业封存和生物封存, 工业封存包括地质封存、海洋封存、矿石碳化以及工业循环利用, 这些方法能快速回收CO₂, 但工艺流程技术复杂, 成本较高。木材碳封存是生物碳封存的一种类型, 树木光合作用吸收的碳主要存贮在木材中。运用木材密度、微密度等检测仪器, 通过确定木材密度变化, 结合其含碳率来计量木材的碳封存过程以及封存过程中碳的分配格局, 同时研究其与环境因子的相关性, 可以为研究森林的碳吸收动态提供便捷的方法和科学的依据。     

Natural regeneration in patch clear-cutting in Picea abies stands in Southern Finland

Abstract

The success of natural regeneration on patch clear-cuts in Norway spruce stands in Southern Finland was examined in terms of stocking and tree height. The experiment was established in mature spruce stands in the submesic Myrtillus (MT) site type. In each of the eight study sites, three plots were treated with clear-cutting and planting, clear-cutting with partial tree retention and planting, and patch clear-cutting without site preparation, respectively. In three of the study sites, one plot with patch clear-cutting and site preparation was established. Each plot was 1 ha, out of which three patches of 40×40 m were clear-cut in the patch treatments. 10–11 years after cutting, the patches had on average 1316 crop trees ha^–1, of which 91% were spruces. Some 27% of the stands were up to the target stocking level (≥1600 ha^?1), and 36% were at least satisfactory (≥1300 ha^?1). Site preparation did not yield greater stocking levels on patches, but that result is ambiguous due to a difference in initial stocking. The average spruce tree height in the patches (0.76 m) was much smaller than in the case of clear-cutting and planting (2.42 m). In conclusion, the patches had been restocked tolerably well with spruce and birch for practical purposes during the 10- to 11-year period, but the regeneration process had been very slow compared to clear-cutting and planting.     

Tree regeneration in patch cutting in Norway spruce stands in northern Finland

The study focused on the success of regeneration on patch cuts in spruce-dominated stands in terms of stocking and tree height. It was based on an experiment in the Kainuu region in northern Finland. The experimental design included 8 stands with 58 clearcut patches of variable size (0.09–0.37?ha), on which either natural regeneration without site preparation or site preparation and planting of Scots pine was applied. A regeneration survey was conducted 13–15 growing seasons after treatments. Patches without site preparation had been restocked quite well from natural seed sources. The average number of trees was about 11,000?ha^?1, of which 1700?ha^?1 crop trees. With site preparation and planting, the stocking levels were also very high, 25,000 and 2100?ha^?1, respectively. One hundred percent of the planted patches and 75% of the naturally regenerated patches had an acceptable density. Restocking was equally good across the range of patch sizes. Tree growth had been somewhat slower in the smallest patches than in the largest ones in the range. Natural regeneration was capable of yielding good regeneration results in most patches, especially when site preparation was applied. Stocking levels and height development were higher yet in the planted patches.     

Changes in micropores in dry wood with elapsed time in the environment

To investigate the changes in microstructures of wood with elapsed time in the environment, CO₂ adsorption onto dry wood was measured at ice-water temperature (273 K) for samples aged from 0.1 years to over 1000 years. The micropore size distribution was obtained using the Horvath-Kawazoe method. Micropores smaller than 0.6 nm in wood decreased in number with elapsed time in the environment, and a negative correlation was found between cumulative pore volume for pores smaller than 0.6 nm and elapsed time in the environment. Cumulative pore volume in the 1000-year sample was almost half of that in the 0.1- year sample. Micropores smaller than 0.6 nm in wood with a few decades or more of elapsed time increased in number after rewetting and drying. Consequently, microstructures of wood with longer time elapsed in the environment were considered to be more stable, because of longer-term thermal motion and possibly more repeated moisture adsorption and desorption and/or temperature variation in the environment.