不同林龄华山松人工林土壤养分及其生态化学计量特征

为了阐明林龄对华山松人工林土壤养分以及碳(C)、氮(N)、磷(P)生态化学计量特征的影响，在贵州省毕节市境内的乌蒙山选取4个林龄(10,16,22,47a)的华山松人工林为研究对象，在每个林分内选择具有代表性的地段分别设置3块20 m×20 m样地，每块样地内按“S”形设置5个采样点，测定0～20 cm土层土壤的pH、总碳(TC)、全氮(TN)、全磷(TP)、全钾(TP)、全钙(TC_a)、有机碳(SOC)、速效氮(AN)、速效磷(AP)、速效钾(AK),并计算土壤C∶N∶P化学计量比，分析它们随林龄的变化及其与C∶N∶P化学计量比之间的关系。结果表明：1)不同林龄华山松人工林土壤SOC含量23.624～65.093g/kg, TN含量1.533～5.157g/kg,远高于全国土壤的平均水平；TP含量0.327～1.097g/kg,与全国土壤平均水平相当，说明研究区内土壤C,N含量较高；2)林龄对华山松人工林土壤养分和C∶N∶P生态化学计量比均有显著影响；随着林龄增长，华山松人工林土壤TC,SOC含量，C∶N和C∶P先降低后增加，TN,TP,AN,AP和AK含量逐渐...     

桂北不同林龄桉树人工林土壤生态化学计量特征

采用时空互代法,探讨不同林龄对桂北低山丘陵地区桉树林土壤SOC,TN,TP和TK养分变化及其生态化学计量学特征的影响。结果表明:1)随林龄的增加,SOC表现为先升高后降低再增加的趋势,TN无明显变化规律,TP趋于减少,TK表现为先减小后增大的趋势。不同林龄SOC,TN,TP和TK含量均随土层深度的增加而减少。2)随林龄的增加,土壤C∶N,C∶P,N∶P和C∶K表现为逐渐增大的趋势,N∶K表现为先增大后减小的趋势,P∶K无明显规律。随土层的加深,土壤C∶N逐渐增大,N∶P,N∶K逐渐减小。C∶P,C∶K和P∶K无明显变化规律。3)SOC与C∶P,N∶P,N∶K呈极显著正相关,TN与N∶P,N∶K呈极显著正相关。TP与N∶K呈极显著正相关,TK与N∶P呈极显著正相关。不同林龄、土层深度均影响土壤养分的分配,土壤养分对桉树林土壤化学计量的贡献表现出一定的差异性。     

不同龄组兴安落叶松林土壤养分及其化学计量特征

以内蒙古大兴安岭不同龄组兴安落叶松林为研究对象,分析土壤养分含量及化学计量特征的动态变化。结果表明:1)土壤有机碳(SOC)与土壤总氮(TN)、碳磷比(C∶P)、氮磷比(N∶P)具有极显著正相关关系;土壤TN与C∶P,N∶P呈极显著正相关关系;土壤铵态氮(NH~+_4-N)与土壤硝态氮(NO~-_3-N),C∶P,N∶P呈极显著正相关;土壤C∶N与C∶P呈显著正相关;土壤C∶P与N∶P呈极显著相关。2)随林龄的不断增加,土壤SOC,TN含量及C∶N,C∶P,N∶P表现出先升高而后降低的趋势,近熟林达到最高;土壤总磷(TP)含量呈先降低后升高的趋势,中龄林最低;土壤铵态氮与土壤硝态氮的含量无显著变化规律;而土壤养分含量逐渐降低。3)土壤容重随林龄的增加表现出降低的变化趋势,各龄组土壤容重之间差异均不显著。土壤TP与土壤容重无显著相关关系,土壤SOC,TN与土壤容重具有显著相关性。     

赤峰市油松人工林土壤碳储量研究

文章以赤峰市油松人工林的土壤为研究对象,采用土壤剖面法和分层取样法,研究了不同深度下土壤容重和有机碳含量。结果表明:1油松各林龄不同土壤深度的平均容重在1.1~1.6g/cm~3之间。2油松人工林不同林龄在同一土层深度的平均含碳量随林龄增大而增加;同一林龄的土壤平均含碳量随土壤深度的增加而下降,且其变化呈乘幂关系。3油松人工林各土壤不同深度碳密度随林龄增加先升高后下降,0~1 m内的土壤碳密度先下降后升高。4截止到2013年末,赤峰全市油松人工林土壤层总碳储量为1.049×10~7t。     

不同林龄无瓣海桑人工林土壤生态化学计量特征

为探究不同林龄无瓣海桑林土壤养分及其生态化学计量特征变化,通过测定10,15,22 a共3个林龄无瓣海桑林0～30 cm土层土壤的pH值、含盐量(TDS)、有机碳(SOC)、全氮(TN)、碱解氮(AN)、全磷(TP)、有效磷(AP)、全钾(TK)和速效钾(AK)含量,计算化学计量比,并分析各指标间的相关性。结果表明：1)造林后,土壤pH值表现为先上升后下降,土壤养分明显增加,土壤SOC,TN含量高于全国土壤平均水平,TP含量略低于全国土壤平均水平;2)不同林龄土壤理化性质及生态化学计量比均存在显著差异,随林龄的增加,土壤pH值先增加后降低,SOC,TN,AN,TP和AK含量先降低后增加,TK和AP变化不明显;3)无瓣海桑林的生长发育可能受到氮(N)的限制,尤其是林龄幼中期影响较大。无瓣海桑人工林对红树林湿地土壤养分的恢复具有明显的调节作用。     

中亚热带4种森林土壤碳、氮、磷化学计量特征

以湘中丘陵区杉木人工林(CL)、马尾松—石栎针阔混交林(PM)、南酸枣落叶阔叶林(CA)、石栎—青冈常绿阔叶林(LG)为对象,研究了中亚热带森林土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量及其生态化学计量特征。结果表明:同一土层SOC、TN、TP含量随着森林树种增加而增加,LG、CA 0~30 cm土层SOC平均含量显著高于CL,但与PM差异不显著,CA各土壤层TN平均含量均显著高于CL、PM,但与LG差异不显著,CA各土壤层TP平均含量显著高于CL、PM、LG;4种森林土壤SOC、TN含量随土壤深度增加而下降,呈"倒金字塔"的分布模式,但TP含量随土壤深度变化不明显,呈"圆柱体"的分布模式。LG各土壤层C:N、C:P平均比值最高,其次是PM,CA、CL最低,但4种森林同一土层N∶P平均比值差异不显著,4种森林0~30 cm土层的C∶N∶P平均比值均明显高于我国土壤C∶N∶P比值的平均值(60∶5∶1),C∶N、C∶P、N∶P比值均随土壤深度增加而下降,不同森林之间的差异也随土壤深度增加而减弱。土壤SOC、TN、TP相互之间的耦合关系显著,C∶N、C∶P比值主要受土壤SOC含量的影响,N∶P比主要受到土壤SOC、TN含量的影响,土壤C∶P比对土壤C∶N、N∶P比值影响显著。     

不同整地方式对长江滩地防护林土壤有机碳和全氮含量及密度的影响

湿地土壤碳(C)和氮(N)在湿地生态系统和全球碳氮循环中起着重要作用。为了阐明人类活动对湿地生态系统C库和N库的影响,本研究以西洞庭湖开沟和不开沟整地滩地防护林为研究对象,通过系统调查和土壤样品采集分析,探讨了不同整地方式对长江中下游滩地防护林土壤C和N的影响。研究结果表明：在不开沟样地中,0～100 cm土层土壤有机碳(SOC)和全氮(TN)含量及密度的变化均表现为CK>8年林龄>3年林龄;在开沟造林样地中,SOC和TN含量和密度在0～30 cm和30～60 cm土层随林龄增大先增加后减小,而在60～100 cm土层随林龄增大而减小。整地方式显著影响土壤SOC和TN含量,但对土壤SOC和TN密度影响不显著。因此,应合理确定长江中下游滩地防护林的规模,禁止在相对高程较低的区域采用开沟方式营建防护林。     

不同林龄樟树林土壤碳氮贮量及分布特征

对湖南省长沙市天际岭国家森林植物园和汨罗桃林林场立地条件基本一致的三个林龄的樟树林土壤有机碳(SOC)、全氮(TN)含量、贮量及土层分布进行研究。结果表明:同一林龄的不同土层SOC、N含量和贮量均存在显著性差异(p<0.05),3个林龄樟树林SOC和TN含量均随土层深度增加而逐渐下降。同时,土壤碳含量及碳贮量林龄的增大而增大,而土壤氮含量及贮量随着林龄的增大而减少,这种变化主要表现在土壤表层(0~10 cm)。不同林龄樟树林各土层SOC含量的变化分别为10 a:4.62~17.00 g/kg,24 a:4.48~17.92g/kg,45 a:4.57~19.37 g/kg;土壤N含量的变化范围分别为10 a:0.99~1.56 g/kg,24 a:0.79~1.43 g/kg,45 a:0.78~1.22 g/kg。土壤SOC含量与N含量存在极显著相关性(p<0.01),土壤SOC含量与C/N相关性极显著(p<0.01)。但樟树林土壤N与C/N之间相关性除24 a呈显著相关以外(p<0.05),其它两个林龄阶段相关性均不显著(p>0.05)。土壤SOC贮量差异不显著(p=0.083),N贮量差异性不显著(p=0.348)。     

不同种植年限尾巨桉人工林叶片-凋落物-土壤碳氮磷化学计量特征

[目的]为了解雷州半岛尾巨桉速生人工林生态系统的C、N、P分配格局及化学计量特征。[方法]采用空间换时间的方法,选取雷州半岛4种不同林龄(1、3、5、7 a)的尾巨桉人工林为研究对象,对尾巨桉叶片、凋落物及土壤的C、N、P含量及化学计量特征进行测定分析。[结果]表明:C、N含量表现为叶片凋落物土壤,P含量表现为叶片土壤凋落物,且3个库间差异显著;土壤的C含量随林龄增加而增加,N、P含量差异不显著,土壤C∶N随林龄的增加而增加,说明土壤有机质分解速率逐渐下降;凋落物的C∶N为54. 07 92. 18 ( 25),表明尾巨桉林下凋落物分解速率较慢,N元素成为主要限制凋落物分解的元素,凋落物的C∶N随林龄的增加先增加后下降,凋落物分解速度先降低后升高;叶片的N∶P为10. 80 12. 98,说明中幼林龄尾巨桉受N限制较明显。相关性分析表明:凋落物养分元素含量受叶片限制,土壤养分含量受凋落物限制,表明生态系统内部C、N、P元素在植物、凋落物与土壤之间实现了运输和转换。[结论]雷州半岛尾巨桉中、幼林龄时期土壤有机质及凋落物分解速率较慢;随林龄的增加,土壤有机质、凋落物分解速率下降,N元素成为其主要分解限制性元素,林分生长受N限制明显。     

安新县不同利用方式土壤碳氮磷及生态化学计量特征研究

为探明安新县不同土地利用方式土壤碳氮磷及生态化学计量特征,以裸地、水田、水浇地、林地和芦苇地5种典型的土地利用方式土壤为研究对象,分析了0～100 cm土壤总有机碳(SOC)、全氮(TN)、全磷(TP)和化学计量数(C/N、C/P、N/P)的分布特征。结果表明:(1)5种土地利用方式土壤SOC、TN含量随土层深度增加而逐渐降低,TP随土层深度无明显变化;裸地、林地和芦苇地土壤C/P、N/P随土层深度增加逐渐减小。(2)利用方式对土壤C、N、P及生态化学计量产生了显著影响,其中土壤SOC和TN均值由高到低为芦苇地、林地、水田、水浇地、裸地;水田和水浇地在0～20 cm土层TP含量显著大于其他利用方式;0～40 cm土层C、N储量由大到小均表现为芦苇地、林地、水田、水浇地、裸地;裸地土壤C/N、C/P和N/P均表现最小;在0～60 cm土层,水田或水浇地土壤C/N最大,在60～100 cm土层,林地土壤C/N最大;林地和芦苇地C/P和N/P在不同土层间均表现较高。(3)通过典型相关分析,SOC、TN、C/P和N/P与土壤因子中的容重和pH值的累积关系较大。研究结果可揭示土地利用方式对土壤C、N、P及生态化学计量特征的影响,对雄安新区的生态建设和修复提供基础数据支撑。     

施N肥对会同杉木人工林N、P含量的影响

以湖南会同杉木基地Ⅱ号集水区杉木人工林为研究对象,对其进行施N肥实验,并进行一年期采样,测定不同施肥处理下N肥对杉木林N、P含量的影响及杉木器官与土壤N、P含量之间的相关关系。结果表明:施肥能够提高杉木土壤、细根、叶片的N和P含量,其中施N肥25 g/m~2能提高土壤的N、P含量,施N肥25g/m~2比施N肥5 g/m~2和15 g/m~2更能提高土壤中细根的N、P含量,施N肥5 g/m~2比施N肥15 g/m~2和25 g/m~2对提高叶片中的N含量的效果好,施N肥并未提高凋落物N含量。会同杉木人工林氮磷含量的增加说明施肥能够促进杉木林的生长。     

Influence of tree internal N status on uptake and translocation of C and N in beech: a dual 13C and 15N labeling approach

Influence of plant internal nitrogen (N) stocks on carbon (C) and N uptake and allocation in 3-year-old beech (Fagus sylvatica L.) was studied in two 15N- and 13C-labeling experiments. In the first experiment, trees were grown in sand and received either no N nutrition (-N treatment) or 4 mM unlabeled N (+N treatment) for 1 year. The -N- and +N-pretreated trees were then supplied with 4 mM 15N and grown in a 13CO2 atmosphere for 24 weeks. In the second experiment, trees were pretreated with 4 mM 15N for 1 year and then supplied with unlabeled N for 24 weeks and the remobilization of stored 15N was monitored. On the whole-plant level, uptake of new C was significantly reduced in -N-pretreated trees; however, partitioning of new C was not altered, although there was a trend toward increased belowground respiration. The amount of N taken up was not influenced by N nutrition in the previous year. In +N-pretreated trees, partitioning of new N was dominated by the fine roots (59.7% at Week 12), whereas in -N-pretreated trees, partitioning of new N favored stem, coarse roots and fine roots (24, 21 and 31.9%, respectively, at Week 12), indicating the formation of N stores. The contribution of previous-year N to leaf N was about 15%. The N remobilized for leaf formation had been stored in stem and coarse roots. We conclude that, within a growing season, the growth of beech is strongly determined by the availability of tree internal N stores, whereas the current N supply is of less importance.     

N—脱氢枞基—N,N—二羟乙基季铵盐类阳离子表面活性剂合成及性质研究

以脱氢枞胺为基础，合成了三种Ｎ－脱氢枞基－Ｎ，Ｎ－二羟乙基季铵盐类阳离子表面活性剂。对产品结构进行了ＵＶ，ＩＲ，ＮＭＲ及元素分析鉴定，测定了产品的表面物理性质，并对产品的抗菌，缓蚀性能进行了应用研究。     

库尔勒香梨树体生长与15N的吸收及分配动态

为给库尔勒香梨园合理施肥及氮肥利用率的提高提供参考,以6年生库尔勒香梨为研究对象,采用15N同位素示踪技术,研究萌芽前期至果实成熟期库尔勒香梨树体生长和氮素吸收、分配动态。结果表明:库尔勒香梨树体基径随着生育期的推移逐渐增大,于果实成熟期达到最大(8.71cm);库尔勒香梨叶片的叶面积指数、叶绿素SPAD值和叶片光合速率均随着香梨年生育期的推进呈现先增大后减小的趋势,均在第2个快速膨大期达到最大,分别为2.40、42.03和12.50μmol/(m^2·s);在年生育末期,库尔勒香梨单株树体的生物量为19958g,氮素积累量为199.44g,各器官中以当年新生器官果实的生物量和氮素积累量为最高,分别占整株树体生物量和氮素积累量的33.33%和25.08%。不同生育期15N在树体内的运转随生长中心的变化而变化。盛花期15N在1年生枝中的分配势最强,新梢旺长期和第2个快速膨大期15N在叶片中的分配势最强,果实成熟期15N在果实中的分配势最强。在果实成熟期库尔勒香梨树体当季15N肥料利用率为17.35%。     

黄杨绢野螟的观察研究

黄杨绢野螟是为害黄杨科植物的食叶性害虫，在保定１年发生２代，以３龄初幼虫在受害枝端吐丝紧密粘合的两片叶内越冬，每年４月是为害高峰。防治方法，可以人工捕捉幼虫，也可在早期进行化学防治。     

Response of the N and P cycles of an old-growth montane forest in Ecuador to experimental low-level N and P amendments

Atmospheric nitrogen (N) and phosphorus (P) depositions are expected to increase in the tropics as a consequence of increasing human activities in the next decades. In the literature, it is frequently assumed that tropical montane forests are N-limited, while tropical lowland forests are P-limited. In a low-level N and P addition experiment, we determined the short-term response of N and P cycles in a north Andean montane forest on Palaeozoic shists and metasandstones at an elevation of 2100 m a.s.l. to increased N and P inputs. We evaluated experimental N, P and N + P additions (50 kg ha⁻¹ yr⁻¹ of N, 10 kg ha⁻¹ yr⁻¹ of P and 50 kg + 10 kg ha⁻¹ yr⁻¹ of N and P, respectively) and an untreated control in a fourfold replicated randomized block design. We collected litter leachate, mineral soil solution (0.15 and 0.30 m depths), throughfall and litterfall before the treatment began (August 2007) until 16 months after the first nutrient application (April 2009). Less than 10 and 1% of the applied N and P, respectively, leached below the organic layer which contained almost all roots and no significant leaching losses of N and P occurred to below 0.15 m mineral soil depth. Deposited N and P from the atmosphere in dry and wet form were retained in the canopy of the control treatment using a canopy budget model. Nitrogen and P retention by the canopy were reduced and N and P fluxes in throughfall and litterfall increased in their respective treatments. The increase in N and P fluxes in throughfall after fertilization was equivalent to 2.5% of the applied N and 2% of the applied P. The fluxes of N and P in litterfall were up to 15% and 3%, respectively, higher in the N and N + P than in the control treatments. We conclude that the expected elevated N and P deposition in the tropics will be retained in the ecosystem, at least in the short term and hence, N and P concentrations in stream water will not increase. Our results suggest that in the studied tropical montane forest ecosystem on Palaeozoic bedrock, N and P are co-limiting the growth of organisms in the canopy and organic layer.     

Effects of thinning on nitrogen status of a larch plantation,illustrated by 15N natural abundance and N resorption

Larch (Larix spp.) is widely distributed in the boreal and temperate areas. Nitrogen (N) is considered as the major limiting element for these areas. Thinning is a common forest management practice. Thus, it is imperative to obtain a better understanding on how thinning could affect N status of larch plantations, and thus optimize the thinning intensity for sustainable forest management. In this study, we measured N concentrations and ¹⁵N natural abundance (δ¹⁵N) of needles and surface soil (0–10?cm) in a larch plantation with T0, T25 and T50 treatments (0%, 25% and 50% thinning intensities, respectively) in Northeast China. We found that needle and soil δ¹⁵N in T25 was the lowest, and the highest in T50. No significant differences were observed for needle and soil N concentrations among the thinning intensities. T25 exhibited the highest N resorption efficiency, indicating highest N use efficiency. Overall, N cycling in T25 was more closed than the control, and with lower soil N availability, while N cycling in T50 was more opened. Our study indicates that foliar ¹⁵N natural abundance is sensitive to thinning and can be potentially used to optimize thinning intensity from the perspective of N cycling.     

Remobilization and uptake of N by newly planted apple (Malus domestica) trees in response to irrigation method and timing of N application

Environmentally sound management of N in apple orchards requires that N supply meets demand. In 1997, newly planted apple trees (Malus domestica Borkh. var. Golden Delicious on M.9 rootstock) received daily applications of N for six weeks as Ca(15NO3)(2) through a drip irrigation system at a concentration of 112 mg l(-1) at 2-8, 5-11 or 8-14 weeks after planting. Irrigation water was applied either to meet estimated evaporative demand or at a fixed rate. In 1997, trees were harvested at 5, 8, 11 and 14 weeks after planting; and in 1998 at 3 weeks after full bloom. The amount of fertilizer N recovered was similar in trees in both irrigation treatments, but efficiency of fertilizer use was greater for trees receiving demand-controlled irrigation than fixed-rate irrigation. This was attributed to lower N inputs, greater retention time in the root zone and less N leaching in the demand-controlled irrigation treatments compared with fixed-rate irrigation treatments. Less fertilizer N was recovered by trees receiving an early application of N than a later application of N and this was related to the timing of N supply with respect to tree demand. Demand for root-supplied N was low until 11 weeks after planting, because early shoot and root growth was supported by N remobilized from woody tissue, which involved 55% of the total tree N content at planting. Rapid development of roots > 1 mm in diameter occurred between 11 and 14 weeks after planting, after remobilization ended, and was greater for trees receiving an early application of N than for trees receiving a later application of N. Late-season tree N demand was supplied by native soil N, and uptake and background soil solution N concentrations were higher for trees receiving demand-supplied irrigation compared with fixed-rate irrigation. Total annual N uptake by roots was unaffected by treatments and averaged 6-8 g tree(-1). Nitrogen applications in 1997 affected growth and N partitioning in 1998. Trees receiving early applications of N had more flowers, spur leaves and bourse shoots than trees receiving later applications of N. Consequently, more N was remobilized into fruits in trees receiving early applications of N compared with fruits in trees receiving later applications of N. Demand for N in the young apple trees was low. Early season demand was met by remobilization from woody tissues and the timing of demand for root-supplied N probably depends on whether flowering occurs. Method of N delivery affected the efficiency of N use. We conclude that N demand can be met at soil solution N concentrations of around 20 mg l(-1).