三种阔叶次生林的茎流研究

本文测定了白桦林、水曲柳林、蒙古栎林的树干茎流量及其养分元素含量,结果表明:三个林分的茎流差异十分明显(白桦:水曲柳:蒙古栎≈1:2:3),这种差异与树叶形态、枝条分枝角度及林分的叶面积指数有关。茎流中绝大多数元素的含量显著地高于降雨中的含量。蒙古栎林借助于它的形态结构使其根系区域获得的水分、养分最多,从而有助于它适应干旱、瘠薄的立地环境。     

北方阔叶树木固氮与非固氮树种间营养元素含量的差异及数量化分类

研究了北方阔叶树木中固氮和非固氮树种间养分元素含量的差异及季节变化趋势．在生长旺盛期到落叶期固氮和非固氮树种叶片之间Ｎ、Ｍｇ含量始终存在明显差异;固氮树种叶片中Ｎ、Ｋ含量降低的趋势明显低于非固氮树种,所研究的其它５个元素和灰分的季节变化率即累积的趋势则高于非固氮树种．在Ｆ检验和Ｔ检验的基础上,选择Ｎ、Ｐ、Ｍｇ、Ｓｉ４个营养元素为参数进行的数量化分类,成功地区分了固氮和非固氮树种．     

暖温带两种针叶林生态系统中茎流和穿透雨的养分特征研究

通过对暖温带地区两种典型人工针叶林生态系统内树干茎流和穿透雨的收集,对其中Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ、Ｓ和Ａｌ等７种元素进行了测定。研究发现这些养分元素在树干茎流和穿透雨中的含量在年内有明显的时间动态变化,这些变化主要受元素在水分中的含量和它们在植物生命活动中的活跃程度等影响,甚至在不同的针叶林生态系统之间都有一定的差异,其中表现为明显的是Ｎ、Ｋ和Ｓ。     

杉楠混交与人工杉木林自养机制的恢复

自养机制的形成是人工林可持续经营的目标之一。本研究通过混交模拟杉木人工林不同恢复阶段林分,观察比较发现从退化的杉木林阶段到地带性树种比例较低的混交林、地带性树种比例较高的混交林和地带性树种纯林阶段凋落量、Ｎ、Ｐ、Ｋ、Ｃａ和Ｍｇ５种元素的归还量逐渐增加,特别是５种养分元素的循环速率也不断增大,其中Ｎ、Ｍｇ的循环速率由杉木纯林的０．１左右增大到火力楠纯林的０．５以上,与此同时林分土壤有机质含量和养分含     

桂东北栲树林营养元素的空间格局

具有顶极群落稳定性的亚热带天然拷树群落内不同层次、不同树种和不同器官的营养元素含量存在明显差异,反映了该群落大分利用上的多样性。通过分析主要建群树种的养分含量以及营养元素在群落中不同层次和树种中的积累和分配规律,提示出稳定性的养分机制。栲树的５种营养元素累积总量为１７１６．５ｋｇ／ｈｍ＾２,其中,各元素的累积量为：Ｎ５９６．７Ｐ４１．９,Ｋ３９１．４Ｃａ５３８．１ｋｇ／ｈｍ＾２,Ｍｇ１１４８．４．     

黄土高原丘陵沟壑区柠条和沙棘灌丛的降雨截留特征

2011年5-10月,以黄土高原人工造林的主要灌木树种柠条和沙棘为对象,研究了降雨量及降雨强度对其截留量、穿透雨量和树干茎流量的影响.研究期间共观测到降雨47次,以小降雨事件为主,年降雨总量为208.9 mm,平均降雨强度为2.82 mm·h-1,其中降雨量为2～10 mm,降雨强度为0.1～2 mm·h-1的降雨事件出现次数最多.柠条和沙棘的截留量、穿透雨量、树干茎流量分别为58.5 mm、124.7 mm、25.7 mm和38.2 mm、153.1 mm、17.6 mm,分别占降雨量的28％、59.7％、12.3％和18.3％、73.3％、8.4％.柠条和沙棘的截留量、穿透雨量和树干茎流量与降雨量均呈显著正相关,并且两种灌木的截留率、穿透雨率和树干茎流率与降雨量、最大10 min雨强之间均呈指数相关或幂函数相关.     

桦汁的采集与利用

桦树[白桦(Betula platyphylla Suk)、棘皮桦(Beltula claurica Pall)、硕桦(Betuls costata,Trautv.)]受伤后伤口流出的汁液,人们称之为桦汁。用人工在桦树树干下部钻孔亦可采集桦汁。它系一种透明,营养丰富的汁液。桦汁含糖、酸及微量元素、芳香物质等。糖类包括葡萄糖、果糖、蔗糖、麦芽糖等,总含量约为1%;酸类包括烟酸、谷氨酸、     

固氮树种在混交林中的作用研究Ⅱ,固氮树木叶部N,P养分动态特征

研究了２３种固氮与非固氮树种叶部Ｎ,Ｐ含量的季节变化,输出率以及叶片衰老过程中Ｎ,Ｐ输出过程,结果表明,供试树种叶部Ｎ,Ｐ含量均存在着明显的季节变化,平均变化率为２１～２３％,最大变化率出现在叶片衰老期,在衰老期内不同树种表现出不同的Ｎ,Ｐ动态特征,固氮树种表现出输出率,落叶中Ｎ含量是非固氮树种的１．６～３．７倍,固氮树种生长季叶部Ｎ含量在２．５％左右。     

东灵山地区大气降水特征及森林树干茎流

对东灵山地区大气降水特征及森林树干茎流进行了研究,结果表明：年降水量大部分集在６－９月份,日降水以量级低于５．０ｍｍ的小雨较多,单次降水以雨强小于２．０ｍｍ的阵性降水为主,单株树木的干流量以辽东栎（３０．３ｍｍ）最大,棘皮桦（２．９ｍｍ）最小;两个生长季各林分的干流深是;辽东栎林６６．６８ｍｍ,３５．１９ｍｍ;落叶松林４３．７６ｍｍ,２３．１２ｍｍ;混交林３２．７７ｍｍ,１７．３６ｍｍ;油松林２２     

小龙门林场棘皮桦种群结构分析

调查小龙门林场棘皮桦林的种群结构,编制棘皮桦的生命表,绘制种群的存活及死亡曲线进行生存分析。通过现时不同年龄段的个体数量推测种群时间上的动态过程,结果显示小龙门林场的环境条件比较适宜棘皮桦种群的生长,良好的自然条件使其倾向于产生更具竞争力的后代,而不是大量繁殖。     

Nutrient content of incident rainfall,throughfall and stemflow in a Nigerian secondary lowland rainforest

Abstract. Nutrient content of rainfall, throughfall and stemflow was studied over one year in the open and under the crowns of three tree species in a secondary rain forest at Ile‐Ife, Nigeria. Throughfall and stemflow comprised 78.8 % and 5.2 % respectively; 16.0 % of the incident rainfall was intercepted by the forest canopy. The concentrations of various nutrient elements in throughfall and stemflow were higher than those of incident rainfall. In throughfall and stemflow potassium concentration was highest and that of ammonium nitrogen was the lowest. Only calcium and sodium concentrations showed significant monthly variation in incident rainfall. Ca, Mg, K. Cu and P showed significant monthly variation in throughfall and stemflow. The concentrations of the elements were highest during the heavy‐rain months (May‐September). High concentrations of some of the elements were recorded also in November, the last rain month and the beginning of the dry season. The concentration of these elements in stemflow and throughfall was affected by tree species. The highest quantity of each element was deposited in the forest via throughfall followed by incident precipitation and the lowest via stemflow. The tree species affected the quantities of these elements by the volume of their stemflow and throughfall and the concentration of the various elements herein. Total nutrient concentration was much higher than available (dissolved) nutrient concentration. This was very pronounced with micronutrients.     

湿地松人工林中降雨对养分物质的淋溶影响

降雨的水质在通过森林后会发生十分大的变化。本文选择了亚热带湿地松人工林,通过分别实测降雨过程中林外降雨、林内降雨及树干流的变化,及其相应的水质变化,分析了湿地松人工林地内雨量再分配的特点,在此基础上阐述了通过降雨过程湿地松人工林地内营养元素的输入及循环过程的特点。 分析结果表明,林外降雨、林内降雨及树干流的P、N、Ca、Mg、Na、K等浓度有很大的差异。与水分运动相对应,各种元素以点源或面源的形式进入流域,从而构成了两个过程与速度均不同的循环。此外,也讨论了降雨与树表面淋溶作用对林地物质输入的贡献。     

鼎湖山季风常绿阔叶林大气降雨、穿透雨和树干流的养分特征研究

对鼎湖山季风常绿阔叶林大气降雨、穿透雨和树干茎流中的5种养分元素K、Ca、Mg、N、P进行了测定,结合水量分配规律,研究了森林降雨过程中养分在水相中的含量变化特征和输入规律。结果表明：(1)所有离子浓度均为大气降水<穿透雨<树干流,且增幅较大,而平均浓度以K+和总氮(TN)含量最高;总磷(TP)、磷酸盐(HPO42-)、总有机磷(TOP)含量均最低。(2) 大气降雨中的离子平均浓度中以总有机氮(TON)的变异系数最大,为1.282;最小的是NO3-(0.502);穿透雨中变异系数最大的是TOP(2.357);最小的是TN(0.621)。树干流中各养分元素浓度与树种的相关性不显著(P>0.05)。(3) 季风常绿阔叶林树干流和穿透雨各养分对森林土壤的年输入量为TN>K+>Ca2+>Mg2+>TP,树干流和穿透雨对森林土壤层Ca2+的输入大于凋落物分解输入。因此,大气降雨是养分从林冠层转移到土壤层的重要因素。     

鼎湖山酸沉降背景下主要森林类型水化学特征初步研究

雨水的水质在通过森林后会发生变化．如果雨水是酸性的,这种变化会更加明显．通过一年多时间在鼎湖山主要森林类型采样分析发现,鼎湖山大气降水pH值低,酸雨频率高;阔叶林穿透雨pH值比大气降水高,树干径流和地表水pH值比大气降水低,土壤自然酸化非常严重;混交林穿透雨和地表水酸度比大气降水低,树干径流酸度则大于大气降水;针叶林穿透雨和树干径流都有进一步酸化趋势,但地表水pH值比大气降水高．3种林型比较,阔叶林林冠缓冲能力最强,针叶林土壤缓冲能力最大．3种林型,林内降水和地表水养分N、P、K、Ca、Mg和Na含量除N外都明显高于大气降水．各林型树干径流对养分富集能力强于穿透水,养分在大气降水中的浓度低于在地表水中的浓度．针叶林林内降水比混交林和阔叶林养分含量高,但地表水中养分浓度比后两者低．从地表水的养分浓度看,阔叶林和混交林养分亏损更为严重．     

北京西山地区油松林水文过程中营养元素迁移特征

对北京西山地区31a油松林降水化学进行定位监测与分析.结果表明：（1）大气降水流经油松林过程中,其营养元素（除Na^＋外）的浓度出现梯度变化：树干茎流高于穿透雨高于大气降水,并且有明显的月际变化,表明从林冠、树干淋洗大量的营养元素,林冠和树干中养分元素迁移是森林生态系统养分循环重要的组成部分.（2）营养元素变化中,浓度差异变化较大的元素是NO3^--N和K^＋,NO3^--N在穿透雨和树干茎流的浓度分别是大气降水的4.4倍、9.9倍,它们中的K^＋浓度分别为大气降水的4.1倍和8.1倍.（3）降水经过油松林,养分淋溶总量为54.12kg hm^-2,淋溶量较多的元素是Ca和K,淋溶强度最大的元素是K^＋.（4）北京西山地区大气降水输入林地的养分66.38kg hm^-2,较多的元素是Ca、N.降水经过油松林输入林地养分总量为120.50kg hm^-2,Ca元素最高,为61.22kg hm^-2,其次是N元素（NH4^＋-N＋N3^--N）,为31.34kg hm^-2,K元素为16.49kg hm^-2,Mg元素为8.11kg hm^-2,Na元素最少,为3.34kg hm^-2.     

辽东山区次生林生态系统不同林型树干茎流的理化性质

为明确森林对降雨水质的影响,于2011年6-8月,对辽东山区次生林生态系统5种主要林型:落叶松人工林(Larix olgensis)(Lo)、花曲柳林(Fraxinus rhynchophulla)(Fr)、杂木林(Mb)、红松人工林(Pinus koraiensis(Pk)和蒙古栎林(Querus mongolica)(Om)中树干茎流和林外雨理化性质进行了监测.与林外雨相比,5种林型树干茎流均出现明显酸化(P＜0.05),酸化程度为:Pk＞ Lo＞ Fr＞ Om＞ Mb;各林型树干茎流的电导率、总溶解固体含量、氯离子浓度、硝酸根离子浓度、铵根离子浓度浓度和总磷浓度显著升高(P＜0.05),溶解氧浓度明显下降(P＜0.05).林型间相比,Lo与Pk的电导率和总溶解固体含量和Lo的氯离子浓度较高;Lo和Pk的硝酸根离子浓度和总磷浓度明显低于其它林型(P＜0.05);Mb的硝酸根离子浓度和总磷浓度显著高于其它林型(P＜0.05).各林型树干茎流的硝酸根离子浓度和胸径与树高的乘积呈显著正相关.上述结果主要受降雨因素(降雨前干沉降时间长度等)、林分特征(叶面积指数、树皮特征)、树木枝叶表层积累物质的理化性质等影响.结论:各林型树干茎流水质均明显下降,其中Mb树干茎流对雨水化学性质影响较大;Pk和Lo树干茎流水体纯度下降最为显著.     

Rainfall partitioning into throughfall and stemflow and associated nutrient fluxes: land use impacts in a lower montane tropical region of Panama

Land-use change alters catchment hydrology by influencing the quality and quantity of partitioned rainfall. We compared rainfall partitioning (throughfall, stemflow and interception) and nutrient concentrations in rainfall, throughfall and stemflow in three land-use types [primary forest (PF), secondary forest (SF) and agriculture (A)] in Panama. Measurements of throughfall were highly variable which may have masked seasonal and land use differences but it was clear that throughfall at agricultural sites made up a larger proportion of gross precipitation than at forest sites. Of incident precipitation, 94% became throughfall in agriculture sites while 83 and 81% of gross precipitation became throughfall in PF and SF, respectively. The size of the precipitation event was the main driver of variation in throughfall and stemflow. Consistent patterns in nutrient cycling were also difficult to identify. Vegetation has a vital role in delivering nutrients as throughfall deposition of K was often larger than precipitation deposition. A canopy budget model indicated that canopy exchange was often more dominant than dry deposition. Throughfall was generally enriched with nutrients, especially K and Mg, with enrichment factors of up to 17 and 5 for K and Mg, respectively, in PF. In contrast, Ca was sometimes taken up by the canopy. Values of nutrient deposition were high (with up to 15, 3, 30 and 15 kg ha^?1 month^?1 in stand deposition of Ca, Mg, K and Na, respectively in PF), possibly due to the slash-and-burn agricultural practices in the area or marine inputs. Throughfall and stemflow are vital sources of nutrients in these ecosystems.     

Litterflow chemistry and nutrient uptake from the forest floor in northwest Amazonian forest ecosystems

Samples of the fraction of net rainfall passing through the forest floor collected at monthly intervals in four pristine forests in Colombian Amazonia, during the period between 1995–1997 were analysed for solute concentrations to estimate the element fluxes from the forest floor into the mineral soil and root nutrient uptake from these forest floors. Results were compared with inputs by throughfall, stemflow, litterfall and fine root decay. Element concentrations were tested for their relationship with litterflow amounts, rainfall intensity and length of the antecedent dry period and differences in element fluxes between ecosystems were assessed. Concentrations of elements in litterflow followed a similar pattern as those in throughfall, which indicates that element outputs from the forest floor are strongly related to those inputs in throughfall. In the forests studied, the average concentrations of elements as K, Mg, orthoP and the pH of the litterflow decreased relative to that in throughfall in most events, while the concentration of elements such as dissolved organic carbon, H, SO₄ and Si increased in litterflow from these forests. Element concentrations in litterflow showed a poor correlation with variables such as litterflow amounts, rainfall intensity and antecedent dry period, except for K which showed a significant correlation (p>0.95) with analysed variables in all forests. Outputs were significantly different between forests (p>0.95); these fluxes, which particularly concerned cations, being the largest in the flood plain, while for anions outputs increased from the flood plain to the sedimentary plain. After adding the nutrient contributed by litter decomposition and fine root decay, the net outputs of main elements from the forest floors were still smaller than inputs by net precipitation (throughfall+stemflow) indicating that the litter layers clearly acted as a sink for most nutrients. Accordingly, the element balances confirm that the forest floors acted as a sink for nutrients coming in by throughfall, stemflow, litterfall and fine root decomposition. P, Mg and N appeared to be the most limiting nutrients and the forests studied efficiently recycled these nutrients.     

Throughfall,stemflow and interception of rainwater in an evergreen broadleaved forest

In order to analyze the dyanmics of heavy metals in a forest ecosystem, throughfall and stemflow were collected for individual rain showers in an evergreen broad-leaved forest dominated byCastanopsis cuspidata. The relation between throughfall (or stemflow) (Px) and gross rainfall (P) was approximated by a linear regression equationPx=a(P-b). The values of coefficient “a” were 0.32–2.02 for throughfall at each sampling point and the mean values for 1976 and 1977–1978 were 0.682 and 0.767, respectively. The stemflow volume differed widely among individual trees, depending mainly on the tree form of each species. In particular, the tree form ofPasania edulis was found to be especially suited to collecting stemflow. OneP. edulis tree collected 64% of the rainwater that fell onto its crown as stemflow. The ratio of stemflow to gross rainfall decreased in summer resulting from an increase in leaf biomass and an increase in air temperature. In fact, the values of coefficient “a” for mean stemflow per unit area were 0.180 for summer and 0.229 for other seasons in 1976, and 0.145 for summer and 0.155 for other seasons in 1977–1978 for different sampled trees.