金鸡林场3种森林群落类型生态特征的对比研究

对信丰县金鸡林场次生常绿阔叶林、杉木人工林和天然马尾松林３森林类型进行了研究。表明，３种森林类型下木层组成结构次生常绿阔叶林最复杂、杉木人工林次之、天然马尾松林最简单、下木层植物种类分别为７８种、４６种和２８种；Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ物种多亲性指数分别为４．１－４．９，１．４－４．１和０．７－１．９；林分蓄积量杉木人工林最高、次生常绿阔叶林次之、天然马尾松林最一次生绿阔叶要高于杉木人林；枯落     

四川盆周山地杉木人工林衰退与铝毒害阈值的探讨

根据四川盆周山地杉木人工林调查分析数据,借鉴国内外森林土壤酸化研究方法,在立地分类基础上,确定二代杉木人工纯林作为研究对象,选择根际土壤ｐＨ 值（ＫＣｌ） 、Ａｌ３＋ 、Ｃａ２＋ ／Ａｌ３ ＋ 和凋落物Ｃａ２ ＋／（Ｃａ２ ＋ ＋Ｆｅ３＋ ＋ Ａｌ３＋ ） 作为参数,探讨杉木人工林衰退与铝毒害阈值。研究结果表明,有的林地立地质量差,树种与立地不相适应,导致杉木人工林生产力下降;另有的林地,虽然立地条件较好,但是已出现铝毒害,导致杉木人工林衰退。铝毒害阈值是ｐＨ≤４－１８ ,Ａｌ３ ＋ ≥３１－６６ ｍｇ／ｋｇ,Ｃａ２ ＋ ／Ａｌ３＋ ≤１－８０９ ｍｏｌ／ｍｏｌ 和Ｃａ２＋ ／（Ｃａ２ ＋ ＋ Ｆｅ３ ＋ ＋ Ａｌ３＋ ）≤０－５５ ｍｏｌ／ｍｏｌ。     

热带山地雨林生态系统对降雨水质的影响

３ａ对同岛尖峰岭热带山地雨林集水区岩石、土壤及水化学质流含量的检测,雨林集水区降雨、总径流水体ＣＯＤ、ＮＨ４＾＋－Ｎ、酚、Ｚｎ、Ｃｕ、Ｐｂ、Ｃｄ、Ｎｉ的加权浓度含量远低于地面水质Ⅰ类标准;岩石组成属钾长石类,其８项测定的重金属中Ｚｎ、Ｍｎ、Ｐｂ含量相对较高,水质迁移中以溶解、水解及氧化为特征;在降雨一径流水循环中,山地雨林冠层减少降雨中ＣＯＤ、ＮＨ４＾＋－Ｎ、酚、Ｚｎ、Ｃｄ、Ａｓ、Ｎｉ、Ｆｅ浓度含     

酸雨pH值对福建省森林土壤酸中和能力的影响

本文研究了酸雨ｐＨ值对福建省森林土壤酸中和能力的影响，结果表明：福建省森林土壤的酸中和能力主要取决于土壤对ＳＯ２－４的吸附能力；在试验范围内，降雨ｐＨ值与土壤ＡＮＣ和ＡＮＣｃ值呈显著正相关，而与ＡＮＣａ值无显著相关性     

激素,钙,水杨酸和铵诱导马尾松,黑松抗松材线虫病的研究

诱抗试验结果表明：（１）ＩＢＡ、乙烯、ＩＢＡ＋乙烯对马尾松的诱抗效果达６０％，而ＩＢＡ＋乙烯对黑松苗的诱抗效果为１２．５％。（２）Ｃａ＾２＋ＩＢＡ对黑松苗的诱抗效果为３６．６７％。（３）除Ｓａ＋ＩＢＡ对黑松苗的诱抗效果为１６．７％外，其余Ｓａ的各处理效果均不明显。（４）铵的单用、混用或与Ｃａ＾２＋混用对马尾松诱抗效果均可达６６．８％￣１００％。     

杉木林截留对降水化学的影响

在福建南平地区，选择离污染源距离不同的两片杉木工人林建立监测场，对降雨、穿透雨和树干径流化学进行了连续３年（１９９４￣１９９６）的定位研究。降雨通过林冠后，其化学性质发生了显著的变化。穿透雨较降雨的ｐＨ值稍低，但伴随离子浓度的增加，穿透雨的电导率明显升高，而树干径流的酸化和养分富集现象均十分显著。降雨和穿透雨酸度表现出一定的季节变化趋势，其最低月均ｐＨ值普遍出现在夏季，最高值在冬季。而降水电导率则表现出与离子浓度相同的明显的季节变化格局，两者月均值均以夏季最低，冬了最高，春秋季居中，这种格局强烈受降雨量的控制。树干径流酸度与ＳＯ４＾２－浓度之间密切相关，但降雨和穿透雨的氢离子浓度和酸－碱离子浓度比Ｒ〔Ｒ＝（ＳＯ４＾２－＋ＮＯ３＾－）／（Ｃａ＾２＋＋Ｍｇ＾２＋）〕间相关显著。离污染源距离的远近对降水化学的影响也比     

山东滨海地区盐碱地土壤分析研究

在山东滨海的海浸盐渍区，根据地表植被的种类，分布，生长情况和土壤返盐情况，分别在轻，中，重度盐地和作物能正常生长的农耕地采集土样，样品分析测定结果表明；盐碱地的土壤电导度过大，平均高出农耕地２－４倍，具明显的上轻下重特征；土壤ｐＨ（Ｈ２Ｏ）平均在９．３～９．７之间，碱性过强，盐基Ｍｇ＾２＋含量与农耕地差别不大，Ｃａ＾２＋，以农耕地为多，但Ｎａ＾＋，Ｋ＾＋含量显著高于农耕地，钠盐危害和离子平衡关系失     

热带山地雨林生态系统水文化学循环规律的研究

根据５ａ定位观测，对尖峰岭热带山地雨林更新林生态系统的水文化学循环规律数据分析表明，年均降雨量为２６６８．３ｍｍ，其中总径流量占４６．７％，蒸散量５３．３％，冠层留量１４．０％。Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ的年均降雨输入量为７８．４ｋｇ（ｈｍ＾２．ａ），总径流输出５６．７ｋｇ／（ｈｍ＾２．ａ），净积累２１．６ｋｇ／（ｈｇｍ＾２．ａ），Ｓｉ，有机Ｃ、Ａｌ、Ｍｎ的年均降雨输入量为２５．０ｋｇ（ｈｍ＾２．ａ）     

热带山地雨林生态系统水文化学循环规律的研究

根据５ａ定位观测，对尖峰岭热带山地雨林更新林生态系统的水文化学循环规律的数据分析表明，年均降雨量为２６６８．３ｍｍ，其中总径流量占４６．７％，蒸散量５３．３％，冠层截留量１４．０％。Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ的年均降雨输入量为７８．４ｋｇ／（ｈｍ２·ａ），总径流输出５６．７ｋｇ／（ｈｍ２·ａ），净积累２１．６ｋｇ／（ｈｍ２·ａ）；Ｓｉ、有机Ｃ、Ａｌ、Ｍｎ的年均降雨输入量为２５．０ｋｇ／（ｈｍ２·ａ），总径流输出为１１２．３ｋｇ／（ｈｍ２·ａ），净损失８７．３ｋｇ／（ｈｍ２·ａ），更新林系统仅处于更新进展过程中，同时证实了冠层对降水化学的淋溶效应，净淋溶系数达４．１１；提出了降雨、林内净降雨、总径流的各水化学物含量与其相应水量的回归模式     

几个绿化树种对大气中若干元素作用规律的研究

通过对油松、雪松、云杉、水杉、毛白杨等５个树种穿透降雨的研究得出：不同树种对大气中各元素的吸附聚集能力不同。根据综合评价,各树种对ＮＯ３－－Ｎ、ＮＨ４＋－Ｎ、ＰＯ４３－、Ｋ、Ｎａ、Ｃａ、Ｍｇ、Ｚｎ、Ｍｎ、Ｃｕ、Ｐｂ、Ｃｄ的综合吸附能力为：雪松＞云杉＞油松＞毛白杨＞水杉。     

重庆酸雨区缙云山典型林分冠层酸雨淋洗特征

选取重庆缙云山的针阔混交林、常绿阔叶林、毛竹林、灌木林4种典型林分,观测酸性降水过程中林外雨、穿透雨及干流等林内水分转换分量中的主要离子含量变化,分析林分冠层对雨水化学组成的影响,结果表明:(1)降雨中的离子当量浓度大小依次是SO42-＞Ca2+＞ NH4+＞Mg2+＞K+＞Na+＞NO3-;(2)降雨经过林冠层后pH值降低,干流的酸化程度增加最大;(3)降雨经林冠层后离子浓度明显增加(除灌木林),穿透雨中通量增加最大的阴离子和阳离子分别为SO42-(2.19×103～6.47×103 eq·hm-2)和Ca2+(1.41×103～3.39×103 eq-hm-2),离子来源主要为大气沉降和植物分泌物或淋出;(4)同一离子在不同林分的干流和穿透雨中的通量变化不同,反映出不同林分冠层的离子交换性差异.在针阔混交林中,林下降雨净淋溶量大小顺序为SO42-＞Ca2+＞ NO3-＞K+＞NH4+＞Mg2+＞ Na+;常绿阔叶林为SO42-＞ Ca2+＞ K+＞NO3-＞ NH4+＞ Mg2+ ＞Na+;毛竹林为Ca2+＞ SO42-＞ K+＞NO3-＞ NH4+＞Na+＞Mg2+;灌木林为Ca2+＞ NO3-＞ K+＞ Na+＞Mg2+＞ NH4+＞ SO42-.     

Canopy leaching of subtropical mixed forests under acid rain

Leaching of major ions from acid precipitation in a subtropical forest was examined based on an experiment in four sample sites in Shaoshan City, Hunan Province, China, from January 2001 to June 2002. Results clearly show that when rain passed through the canopy, pH increased and the evidence of ion uptake was presented for SO₄ ²⁻, NO₃ ⁻, Mg²⁺ and NH₄ ⁺ ions, especially of NH₄ ⁺ and NO₃ ⁻. The percentages of dissolved SO₄ ²⁻, Ca²⁺ and Mg²⁺ show a decreasing trend with increasing rainfall. Percentages of leaching Ca²⁺, K⁺ and Cl⁻ ions show an increasing trend as a function of increased pH values. The forest canopy in Shaoshan City has a strong effect on the uptake of SO₄ ²⁻ and NO₃ ⁻ ions under acid rain conditions. The decreasing order of ions leaching in the forest canopy is as follows: K⁺ > Ca²⁺ > Cl⁻ > Mg²⁺ > SO₄ ²⁻ > NO₃ ⁻ > NH₄ ⁺ > Na⁺. __________ Translated from Scientia Silvae Sinicae, 2007, 43(7): 1–4 [译自: 林业科学]     

Transfer characteristics of nutrient elements through hydrological process of a Pinus tabulaeformis stand in the West Mountain of Beijing

Forest precipitation chemistry is a major issue in forest hydrology and forest ecology. Chemical contents in precipitation change significantly when different kinds of external chemical materials are added, removed, translocated and transformed to or in the forest ecosystem along with precipitation. The chemistry of precipitation was monitored and analyzed in a 31-year-old Pinus tabulaeformis forest in the West Mountain of Beijing. Movement patterns of nutrient elements in hydrological processes can be discovered by studying this monitored data. Also, the information is useful for diagnosing the function of ecosystems and evaluating the impact of the environment on the ecosystem. Samples of rainfall, throughfall and stemflow were collected on the site. In the lab, Ca²⁺ and Mg²⁺ were analyzed by flame atomic absorption and K⁺ and Na⁺ by flame emission. NH₄ ⁺-N was analyzed by indophenol blue colorimetry and NO₃ ⁻-N was analyzed by phenoldisulfonic acid colorimetry. The results showed that: 1) The concentration gradient of nutrient elements clearly changed except for Na⁺. The nutrients in stemflow were significantly higher than those of throughfall and rainfall as the precipitation passed through the P. tabulaeformis forest. The monthly patterns showed distinct differentiation. There are indications that a large amount of nutrients was leached from the canopy, which is a critical function of intra-ecosystem nutrient cycling to improve the efficiency of nutrient use. 2) The concentrations of NO₃ ⁻-N and K⁺ changed more than those of the other nutrient elements. The concentration of NO₃ ⁻-N in throughfall and stemflow was 4.4 times and 9.9 times higher than those in rainfall, respectively. The concentration of K⁺ in throughfall and stemflow was 4.1 times and 8.1 times higher than those in rainfall, respectively. 3) The leaching of nutrient elements from the stand was an important aspect of nutrient return to the P. tabulaeformis forest, which returned a total amount of nutrient of 54.1 kg/hm², with the contribution of Ca²⁺ and K⁺ much greater than that of other elements. Also, K⁺ was the most active element in leaching intensity. 4) Nutrient input through precipitation was the main source in the West Mountain of Beijing and the amount of nutrient added was 66.4 kg/hm², of which Ca²⁺ and N contributed much more than the other nutrient elements. When precipitation passes through the P. tabulaeformis forest, 121 kg/hm² of nutrient is added to the forest floor. Ca²⁺ recorded the greatest nutrient increase, with 61.2 kg/hm², followed by N (NH₄ ⁺-N and NO₃ ⁻-N), K⁺ and Mg²⁺, with 31.3 and 16.5, and 8.11 kg/hm², respectively. The least was Na⁺, 3.34 kg/hm². Translated from Acta Ecologica Sinica, 2006, 26(7): 2,101–2,107 [译自: 生态学报]     

Deposition pattern of precipitation and throughfall in a subtropical evergreen forest in south-central China

The effects of dry deposition, canopy leaching, precipitation ion concentration, and precipitation H⁺ concentration on net throughfall flux (NTF, throughfall minus bulk precipitation) were evaluated on a seasonal basis by using a multiple regression analysis approach based on an observation period of 4 years in Shaoshan subtropical mixed evergreen forest, south-central China. Regression analysis results indicated that the estimated canopy exchange flux was the dominant factor regulating the NTF and the calculated dry deposition was a minor term. The seasonal dry deposition of base cations accounted for 15%–43% of the NTF. The NTF analysis showed that K⁺, Ca²⁺, Mg²⁺, Na⁺, and weak acids in throughfall were derived from foliar leaching and the canopy uptakes of H⁺, NH₄ ⁺, and NO₃ ⁻ were from precipitation. The retention rate of proton (H⁺ and NH₄ ⁺) in the canopy was close to the canopy leaching rate of base cations when corrected for weak acids because weak acid-induced canopy leaching did not exchange with protons, which suggested that the canopy leaching processes neutralized acid precipitation in Shaoshan forest.     

An assessment of rainfall modification in mountainous ecosystems dominated by Fagus sylvatica L. and Picea abies (L.) Karst. (Western Balkans,Bulgaria) by multivariate analyses

Bulk precipitation, throughfall, and stemflow samples were collected in Petrohan site (Western Balkan, Bulgaria), operating in the framework of the Long-Term Ecological Research network, during a 6-year period (1995–2000). This mountain area is characterized by the presence of beech and spruce forests (Fagus sylvatica L. and Picea abies (L.) Karst.) and is utilized for drinking water supply. All samples were analyzed for pH and major inorganic anions (Cl^?, NO₃ ^?, and SO₄ ^2?) and cations (Ca²⁺, K⁺, Mg²⁺, Na⁺, and NH₄ ⁺). Results show that bulk precipitation in this region is mainly acidic (pH = 5.1), and the dominant neutralization components in the rainwater are Ca²⁺ and NH₄ ⁺. As for Ca²⁺, K⁺, Mg²⁺, Cl^?, and SO₄ ^2?, they are not originated by marine source. Cluster analysis and principal component analysis were used for investigating the possible sources contributing to the chemical composition of the bulk precipitation and its possible modifications during the passing through beech and spruce stands. Results highlight that local and long-range transport-related anthropogenic sources and natural sources contribute to the anion and cation content of the bulk precipitation. The enrichment of the solution through the foliage made up of dry depositions is significant in both stands, but canopy leaching processes are much greater in the spruce forest, especially for Ca²⁺. As for the stemflow, it follows the same pattern as the throughfall, but N uptake and a strong K⁺ and Mg²⁺ leaching are observed mainly in the spruce stand.     

Long-term influence of stream water chemistry in Japanese cedar plantation after clear-cutting using the forest rotation in central Japan

Because both natural and anthropogenic disturbances affect biogeochemical cycles in forest ecosystems, monitoring is needed to separate their influences. Chronosequence is very useful for such studies. In our study area, plantation through forest rotation on a watershed basis resulted in more than 40 adjacent watersheds of between 0 and 87 years of stand age, kind of chronosequence. Here, we examined the biological similarity of the watersheds and the long-term effects of clear-cutting on stream water chemistry. The stream water NO₃⁻–stand age relationship was similar between the two observation years; stream water NO₃⁻ concentrations increased dramatically in the watersheds after clear-cutting and decreased in 7–10-year-old replanted watersheds. The slope of stream water NO₃⁻ concentrations between the different watersheds covered by same age stand was significant, at 1:1. Additionally, stream water NO₃⁻ concentrations were more strongly correlated between the different watersheds covered by same aged stand than between the observations at 4 years intervals within a watershed. These findings indicate that stream water NO₃⁻ concentration is mainly regulated by stand age, i.e., by vegetation regrowth, rather than watershed-specific characteristics. Hence, adjacent watersheds are biologically similar apart from stand age and can be regarded as a chronosequence. While there was a clear relationship between stream water NO₃⁻ concentration and stand age, there was significant correlation with stream water SO₄²⁻, Ca²⁺, Mg²⁺, Cl⁻ or Na⁺ between two observations in the same watershed. This indicates that watershed-specific characteristics, rather than vegetation regrowth, control stream SO₄²⁻, Ca²⁺, Mg²⁺, Cl⁻, and Na⁺ concentrations. After 25 years of clear-cutting Ca²⁺, Mg²⁺ and Na⁺ concentrations significantly increased. It is likely the contribution of forest floor accumulation with stand development. Based on these results, clear-cutting influences stream chemistry, not only NO₃⁻, but also the major cation and the influence of clear-cutting continues for several decades at this study site.     

Multiple modelling of water chemistry flows assessed in a mountain spruce catchment

The study was carried out over a period of 1999–2003 in the Dupniański Stream catchment located in Silesian Beskid Mts. Region (Southern Poland). Analysis of the chemical composition of bulk precipitation, throughfall, stemflow, surface flow, soil water (horizontal + vertical and vertical penetration) and outflow water samples was performed. The complex data matrix with more than 3,000 observations of water reaction, major anions (F⁻, Cl⁻, NO₃ ⁻, SO₄ ²⁻) and cations (NH₄ ⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, Fe²⁺, Mn²⁺ and Zn²⁺) were treated by regression modelling. The modelling approach took into account seasonal variability according to winter and growing season, as well as chronosequence of spruce stands. The retention of considerable levels of contaminants by the canopy, and their removal or washout from needles by rainfall caused changes in the concentration of anions and cations reaching the soil surface compared to the concentrations in bulk precipitation. In the youngest stand, most elements except NH₄ ⁺, SO₄ ²⁻ and K⁺ were retained in the canopy, and even H⁺ ions were neutralized. In the older stands, most elements increased in net throughfall fluxes, and the acidity increased strongly. Soil water was slightly correlated with throughfall, while outflow water showed no correlations with the above ground water flows, and seemed to depend mostly of the bedrock.     

Effect of six years of nitrogen additions on soil chemistry in a subtropical <Emphasis Type="Italic">Pleioblastus amarus</Emphasis> forest,Southwest China

Soil chemistry influences plant health and carbon storage in forest ecosystems. Increasing nitrogen (N) deposition has potential effect on soil chemistry. We studied N deposition effects on soil chemistry in subtropical Pleioblastus amarus bamboo forest ecosystems. An experiment with four N treatment levels (0, 50, 150, and 300 kg N ha^?1 a^?1, applied monthly, expressed as CK, LN, MN, HN, respectively) in three replicates. After 6 years of N additions, soil base cations, acid-forming cations, exchangeable acidity (EA), organic carbon fractions and nitrogen components were measured in all four seasons. The mean soil pH values in CK, LN, MN and HN were 4.71, 4.62, 4.71, and 4.40, respectively, with a significant difference between CK and HN. Nitrogen additions significantly increased soil exchangeable Al³⁺, EA, and Al/Ca, and exchangeable Al³⁺ in HN increased by 70% compared to CK. Soil base cations (Ca²⁺, Mg²⁺, K⁺, and Na⁺) did not respond to N additions. Nitrogen treatments significantly increased soil NO₃^?–N but had little effect on soil total nitrogen, particulate organic nitrogen, or NH₄⁺–N. Nitrogen additions did not affect soil total organic carbon, extractable dissolved organic carbon, incorporated organic carbon, or particulate organic carbon. This study suggests that increasing N deposition could increase soil NO₃^?–N, reduce soil pH, and increase mobilization of Al³⁺. These changes induced by N deposition can impede root grow and function, further may influence soil carbon storage and nutrient cycles in the future.     

Soil NH4 +/NO3 − nitrogen characteristics in primary forests and the adaptability of some coniferous species

In terrestrial ecosystems, soil nutrient regimes at a plant’s living site generally represent the plant’s “nutrition habitat”. Plant species frequently well adapt to their original “nutrition habitat” during a long process of evolution, and the apparent preference for ammonium or nitrate nitrogen source (NH₄ ⁺ or NO₃ ⁻) might be an important aspect of the adaptation. Plants typically favor the nitrogen form most abundant in their natural habitats. Nitrate has been recognized as the dominant mineral nitrogen form in most agricultural soils and the main nitrogen source for crops, but it is not usually the case in forest ecosystems. A large number of studies show that the “nutrition habitats” associated with primary forest soils are typically dominated by NH₄ ⁺ rather than NO₃ ⁻, generally with NO₃ ⁻ content much lower than NH₄ ⁺. Low levels of NO₃ ⁻ in these forest soils generally correspond to low net rates of nitrification. The probable reasons for this phenomenon include: 1) nitrification limitations and/or inhibitions caused by lower pH, lower NH₄ ⁺ availability (autotrophic nitrifiers cannot successfully compete for NH₄ ⁺ with heterotrophic organisms and plants), or allelopathic inhibitors (tannins or higher-molecular-weight proanthocyanidins) in the soil; or 2) substantial microbial acquisition of nitrate in the soils, which makes net nitrification rates substantially less than gross nitrification rates even though the latter are relatively high. Many coniferous species (especially such late successional tree species as Tsuga heterophylla, Pinus banksiana, Picea glauca, Pseudotsuga meziesii, Picea abies, etc.) fully adapt to their original NH₄ ⁺-dominated “nutrition habitats” so that their capacities of absorbing and using non-reduced forms of nitrogen (e.g., NO₃ ⁻) substantially decrease. These conifers typically show distinct preference to NH₄ ⁺ and reduced growth due to nitrogen-metabolism disorder when NO₃ ⁻ is the main nitrogen source. The physiological and biochemical mechanisms that account for the adaptation to NH₄ ⁺-dominated systems (or limited ability to use NO₃ ⁻) for the coniferous species include: i) distribution and activity of enzymes for catalyzing nitrogen reduction and assimilation, generally characterized by lower nitrate reductase (NR); ii) greater tolerance to NH₄ ⁺ or rapid detoxification of ammonium nitrogen in the roots; iii) lower capacity of absorption to NO₃ ⁻ by roots that might be controlled by feedback regulations of certain N-transport compounds, such as glutamine; iv) relations and balance between nitrogen and other elements (such as Ca²⁺, Mg²⁺, and Zn²⁺ etc.). Some NH₄ ⁺-preferred conifers might be more adapted (tolerant) to lower base cation conditions; v) NO₃ ⁻ nutrition, rather than NH₄ ⁺, that may lead to the loss of considerable quantities of organic and inorganic carbon to the surrounding media and mycorrhizal symbiont and probably contribute to slower growth; and vi) the metabolic cost of reducing NO₃ ⁻ to NH₄ ⁺ that may make shade-tolerant conifers favor the uptake of reduced nitrogen (NH₄ ⁺). The adaptation of late successional conifers to NH₄ ⁺-dominated habitats has profound ecological implications. First, it might be an important prerequisite for the climax forest communities dominated by these conifers to maintain long-term stability. Second, primary coniferous or coniferous-broadleaved forests have been widely perturbed because of commercial exploitation, where the soil ammonium nitrogen pool tends to be largely transformed to nitrate after disturbance. In such a situation, the coniferous species that were dominant in undisturbed ecosystems may become poor competitors for nitrogen, and the site will be occupied by early successional (pioneer) plants better adapted to nitrate utilization. In other words, the implicit adaptation of many conifers dominant in undisturbed communities to ammonium nitrogen will cause difficulties in their regeneration on disturbed sites, which must be taken into account in the practical restoration of degraded temperate forest ecosystems. __________ Translated from Acta Ecologica Sinica, 2005, 25(11): 3,082–3,092 [译自: 生态学报]