九连山常绿阔叶林不同空间分布的植物叶片N、P化学计量学特征

以九连山常绿阔叶林为实验对象,采用样方取样法对群落中的部分植物叶片N、P元素进行测定,并从不同物种、不同生活型、不同生境类型、不同离地高度等多个空间分布的植物叶片N、P元素化学计量学特征进行统计分析。结果表明:(1)九连山常绿阔叶林群落平均含N量为15.91 mg/g,平均含P量为1.17 mg/g,群落的发展主要受P元素的限制,在物种水平上,不同植物叶片中的N、P元素含量差异较大。(2)群落中蕨类植物通常比被子植物叶片的N、P含量低,不同生活型N、P含量呈现的规律为:草本层乔木层灌木层。(3)山谷植物N、P总体含量明显高于山脊,山谷植物群落主要受到N元素的限制,而山脊植物则主要受到P元素的限制;在一定离地高度内,植物叶片N、P含量逐渐升高,达到最大值后逐渐下降。     

天宝岩典型常绿阔叶林下植被C、N、P含量及化学计量特征

以天宝岩常绿阔叶林林下植被为研究对象,对灌木层和草本层优势植物各器官C、N和P含量进行测定,对其生态化学计量特征及其养分利用策略进行研究.结果表明:(1)灌木层优势植物C含量显著高于草本层,草本层植被N和P含量略大于灌木层,但差异不显著.(2)灌木层优势植物枝器官的C含量显著高于叶和根;叶的N和P含量显著高于其他器官;...     

九连山常绿阔叶林叶片化学元素的空间分布

在九连山国家级自然保护区选择两种生境类型的常绿阔叶林群落,即虾公塘山谷生境类型的群落和山脊生境类型的群落,分别设置群落样方进行调查、取样,并测量了不同植物、不同高度的叶片中12个化学元素的含量,分析、探讨叶片化学元素的空间分布规律。结果表明:群落Ⅰ为罗浮栲林,乔木有8科、12属、16种,群落Ⅱ为米槠林,乔木有10科、11属、14种。在物种水平上,不同植物叶片中的化学元素含量差异较大;不同生境类型条件下,山谷的草本层物种平均化学元素的含量顺序为KCaMgPMnNaFeZnBCuSe,山谷和山脊的灌木层物种平均化学元素含量顺序相同,为KCaMgPMnNaFeZnBCuSe,山谷的乔木层物种平均化学元素含量的顺序为KCaMgPMnNaFeZnBCuSe;山脊乔木层的物种平均化学元素含量顺序为KCaMgPMnNaFeBZnCuSe。其次,同一株植物体不同高度叶片中元素含量差异较大;叶片中元素Fe、Zn、Ca、Mg、B的含量随着枝条离地面的高度升高而减少。另外,不考虑树种种类,元素Fe、Zn、Ca、Mg、B随着采叶高度升高,叶片元素含量减少。九连山常绿阔叶林叶片元素K、Ca、N、Mg、Cu、Fe、Zn、Na、P随着海拔的升高,物种平均化学元素的含量降低,而在B的含量上随着海拔的升高而增大。     

江西武夷山南方铁杉林主要树种叶片养分含量及再吸收效率

【目的】分析江西武夷山南方铁杉林主要树种叶片养分含量,阐明不同生活型(落叶树种和常绿树种)树种新鲜叶和凋落叶养分化学计量特征与养分再吸收效率,为揭示南方铁杉林主要树种叶片养分含量及再吸收效率对植物生活型的响应机制提供理论依据。【方法】采集南方铁杉天然林内主要树种的新鲜叶和凋落叶,测定叶片碳(C)、氮(N)、磷(P)含量,计算其化学计量比和养分再吸收效率,采用标准化主轴回归估计方法对南方铁杉林主要树种新鲜叶与凋落叶中N、P含量的异速生长关系进行研究,分析生活型对叶片N、P含量之间关系的影响。【结果】1)南方铁杉天然混交林中,落叶和常绿两生活型树种间的新鲜叶C含量无显著差异,但落叶树种N和P含量均显著高于常绿树种(P<0.05);但两生活型树种间的凋落叶C、N、P含量均无显著差异。2)新鲜叶C∶N和C∶P均表现为落叶树种显著低于常绿树种(P<0.05),但N∶P在两生活型树种间差异不明显;凋落叶C∶N、N∶P和C∶P均显著大于新鲜叶,但其在两生活型树种间差异不明显。3)常绿树种新鲜叶N与P含量间存在显著正相关关系;常绿树种与落叶树种凋落叶N与P含量显著正相关(P<0.05...     

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。     

南岭自然保护区常绿阔叶林优势树种叶片中11种化学元素含量特征

为探讨南岭自然保护区常绿阔叶林优势树种叶片营养特征及重金属含量水平,测定了保护区16个优势树种叶片中N、P、K、Ca、Al、Na、Mg、Mn、Ni、Cu和Pb共11种化学元素的含量,并分析了其在叶片中的变异特征和相关性。结果表明：该地区植物叶片N、P含量均低于我国陆生植物叶片含量的平均值,叶片Ca、K、Mg含量处于陆地植物叶片的正常范围,叶片Mn含量与广东植物叶片含量接近;16个优势树种叶片重金属含量均处于正常范围;南岭自然保护区优势树种受P限制强烈;尽管16个优势树种叶片暂未受到重金属和Al毒危害,但因华南地区酸沉降引发土壤重金属活化的风险仍存在,应加强对该地区森林土壤化学性质和树木叶片化学元素含量的定期监测研究。     

缙云山常绿阔叶林6个树种凋落叶量及其C、N、P化学计量学季节动态研究

目的 研究6个树种凋落叶C、N、P化学计量学特征及季节动态,分析其与凋落叶量之间的关系。 方法 利用网格法在样地内均匀布设172个凋落叶收集框,每月末定期将收集框内的凋落叶带回实验室,进行分类称量,粉碎后测量其C、N、P元素含量。 结果 （1）缙云山6个树种的凋落节律各不相同。常绿阔叶树种栲（Castanopsis fargesii）和润楠（Machilus nanmu）、常绿针叶树种杉木（Cunninghamia lanceolata）的凋落高峰出现在春季;落叶树种赤杨叶（Alniphyllum fortune）凋落高峰出现在夏季;落叶树种枫香树（Liquidambar formosana）凋落高峰出现在冬季;常绿针叶树种马尾松（Pinus massoniana）全年无明显的凋落高峰。（2）6个树种凋落叶的C、N、P含量分别在481.35～542.23、5.64～11.85、0.39～0.72 g·kg−1之间,N∶P范围为13.05～19.15。（3）6个树种C、N、P含量季节动态明显。马尾松凋落叶C含量与凋落叶产量呈显著正相关关系（P < 0.05）,赤杨叶凋落叶N含量与凋落叶产量呈显著正相关关系（P < 0.05）,栲和马尾松凋落叶P含量与凋落叶产量呈显著负相关关系（P < 0.05）,马尾松凋落叶N∶P与凋落叶产量呈显著正相关关（P < 0.05）。 结论 缙云山常绿阔叶林6个树种凋落叶季节动态各不相同;6个物种呈现出低N和低P的格局,总体表现为受N、P共同限制,且N限制作用要强于P限制;在一个生长季内,6个树种C、N、P化学计量学特征月份间的差异较大,凋落叶量与凋落叶C、N、P含量之间的关系与物种特性有关;凋落叶量与凋落物化学计量特征关系不明显。     

基于生态因子与神经网络的杉木叶片碳氮磷含量预测

目的 利用神经网络所具有的输入层与输出层间存在的高度非线性映射关系,对杉木叶片C、N、P含量实现准确、经济、快捷的预测。 方法 以我国亚热带地区杉木人工林为研究对象,运用径向基函数（RBF）神经网络在杉木叶片C、N、P含量与地理、气候及土壤性质等生态因子间构建最优预测模型,并结合已发表文献数据进行叶片C、N、P含量预测。 结果 模拟预测叶片C、N和P含量分别为476.68、12.27和1.24 mg·g−1,其中N含量远低于我国陆地植物叶片平均含量;叶片C/N、C/P和N/P平均值分别为40.28、412.01和10.50。预测结果与实测值较为符合,表明RBF人工神经网络模型用于预测杉木叶片C、N、P含量与生态因子的关系是可行的。 结论 模型可以较为准确地估测杉木叶片C、N、P含量,平均误差分别为1.82%、9.88%和7.02%。较低的叶片N含量和N/P表明亚热带地区杉木生长主要受到N素限制。     

毛竹林叶片碳氮磷化学计量特征的海拔梯度效应

毛竹是中国重要的经济竹种,区域上具有明显的垂直分布特点。为揭示毛竹林叶片碳氮磷化学计量特征的海拔梯度效应,为毛竹林科学的林分管理与土壤养分补充提供理论依据,测定了3个海拔梯度毛竹林叶片碳(C)、氮(N)、磷(P)含量,分析了其化学计量特征和异速增长关系。结果表明:随着立竹年龄的增大,毛竹林立竹叶片碳、氮、磷含量及N∶P均总体上呈降低趋势,而C∶N、C∶P则总体上呈升高趋势,1度立竹叶片碳、氮、磷含量均显著高于2度、3度立竹,且后2者间碳、氮、磷含量及其化学计量比均无显著差异。随海拔梯度的升高,毛竹林叶片碳含量略有降低,而氮、磷含量呈降低趋势,其中,中、低海拔叶片氮、磷含量显著高于高海拔,且前2者氮含量无显著差异,而磷含量差异显著;叶片C∶N、C∶P、N∶P均呈上升趋势,其中,中、低海拔叶片C∶N显著低于高海拔,中、高海拔叶片N∶P显著高于低海拔,叶片C∶P海拔梯度间差异显著,其他均无显著差异;不同海拔梯度毛竹林叶片碳、氮、磷间呈显著的正异速增长关系,随海拔梯度的升高,C-N、C-P异速增长指数显著下降,而N-P异速增长指数显著提高。研究表明,随海拔梯度的升高,毛竹林叶片氮、磷含量降低,利用率提高,P素限制性作用增强,建议在高海拔毛竹林经营中宜适当增加磷素的补充。     

亚热带4种林分类型枯落物层和土壤层的碳氮磷化学计量特征

【目的】探讨亚热带森林恢复过程中枯落物层和土壤层的C,N,P含量及其化学计量比的变化规律,为阐明亚热带次生林恢复对土壤养分的影响及森林恢复提供科学依据。【方法】采用空间代替时间的方法,以湘中丘陵区杉木人工纯林、马尾松+石栎针阔混交林、南酸枣落叶阔叶林和石栎+青冈常绿阔叶林作为1个恢复系列,分别在其1 hm~2的长期定位观测样地内,沿着坡面选择6块10 m×10 m小样地,每块小样地随机设置2个1.0 m×1.0 m样方,采集地表未分解层、半分解层、已分解层枯落物和0~10,10~20和20~30 cm土层土壤样品,测定C,N,P含量并计算C,N,P的化学计量比。【结果】随着森林恢复和阔叶树比例增大,同一分解层枯落物C含量呈下降趋势,而N和P(除已分解层外)含量大体呈增加趋势;C含量随枯落物分解而下降;马尾松+石栎针阔混交林N含量表现为半分解层已分解层未分解层,杉木人工林、南酸枣落叶阔叶林、石栎+青冈常绿阔叶林表现为半分解层未分解层已分解层;南酸枣落叶阔叶林P含量表现为未分解层半分解层已分解层,杉木人工林、马尾松+石栎针阔混交林和石栎+青冈常绿阔叶林均表现为半分解层最高,已分解层最低(除马尾松+石栎针阔混交林外);同一分解层枯落物C∶N、C∶P和N∶P比值随森林恢复而下降;C∶N、C∶P比值随枯落物分解而下降,N∶P比值无明显变化规律;同一土层C,N,P含量随森林恢复而增加;4种林分0~30 cm土壤层C∶N和C∶P平均比值变化趋势基本一致,石栎+青冈常绿阔叶林最高,其次是马尾松+石栎针阔混交林,杉木人工林最低;4种林分0~30 cm土壤层N∶P平均比值无显著差异;未分解层枯落物C含量与0~10和0~30 cm土层C,N,P含量显著负相关,而N,P含量与0~10和0~30 cm土壤层C,N(除N外),P含量显著正相关;未分解层枯落物C∶N、C∶P和N∶P比值与0~10和0~30 cm土壤层C(除N∶P比值外),N,P含量显著负相关;枯落物层C∶N、C∶P和N∶P比值与土壤层C∶N、C∶P和N∶P比值相关性不显著。【结论】随着森林恢复,阔叶树比例增大,枯落物层C∶N、C∶P和N∶P比值逐渐下降,土壤层C,N,P含量增加,未分解层枯落物C,N,P含量及其化学计量比对土壤层C,N,P含量影响显著。在森林恢复和森林经营过程中,如何调整林分树种组成,改变枯落物层的质量显得十分关键。     

常绿和落叶阔叶树叶中N和P的变化及转移

从叶完全展开到生长季结束对常绿阔叶树种铁冬青、红楠和海桐及落叶阔叶树种日本朴、银杏和木叶的N和P浓度进行了定期测定。结果表明,常绿阔叶树种新叶的N和P浓度从5—7月急剧下降,然后小幅波动,而老叶的N和P浓度变化缓慢。落叶阔叶树种的N和P浓度随着季节的推移而明显下降。大多数树种的P转移率大于N转移率。常绿阔叶树种的N和P的转移率大于落叶阔叶树种。     

庆元林场阔叶林主要类型生物量测定及其评价

根据样地调查获得的数据,选择已建立的各种相关生物量预测模型进行统计,对千岗坑林区分别不同的阔叶林类型进行生物量的测定研究,结果表明,4个主要类型由于树种组成和林龄的不同,其直径分布变异较大,在生物量上阔杉混交林生物量最高达337.3t/hm2,常绿与落叶阔叶林的生物量最低为166.0t/hm2,在各类型的生物量组分中,树干组分的比例最大,其次为枝,再次是根,最低是叶。而生态功能的强弱序列为常绿阔叶林>常绿与落叶阔叶混交林>阔松混交林>阔杉混交林,木材生产能力的大小序列为阔杉混交林>阔松混交林>常绿阔叶林>常绿与落叶混交林。     

Contrasting seasonal leaf habits of canopy trees between tropical dry-deciduous and evergreen forests in Thailand

We compared differences in leaf properties, leaf gas exchange and photochemical properties between drought-deciduous and evergreen trees in tropical dry forests, where soil nutrients differed but rainfall was similar. Three canopy trees (Shorea siamensis Miq., Xylia xylocarpa (Roxb.) W. Theob. and Vitex peduncularis Wall. ex Schauer) in a drought-deciduous forest and a canopy tree (Hopea ferrea Lanessan) in an evergreen forest were selected. Soil nutrient availability is lower in the evergreen forest than in the deciduous forest. Compared with the evergreen tree, the deciduous trees had shorter leaf life spans, lower leaf masses per area, higher leaf mass-based nitrogen (N) contents, higher leaf mass-based photosynthetic rates (mass-based P(n)), higher leaf N-based P(n), higher daily maximum stomatal conductance (g(s)) and wider conduits in wood xylem. Mass-based P(n) decreased from the wet to the dry season for all species. Following onset of the dry season, daily maximum g(s) and sensitivity of g(s) to leaf-to-air vapor pressure deficit remained relatively unchanged in the deciduous trees, whereas both properties decreased in the evergreen tree during the dry season. Photochemical capacity and non-photochemical quenching (NPQ) of photosystem II (PSII) also remained relatively unchanged in the deciduous trees even after the onset of the dry season. In contrast, photochemical capacity decreased and NPQ increased in the evergreen tree during the dry season, indicating that the leaves coped with prolonged drought by down-regulating PSII. Thus, the drought-avoidant deciduous species were characterized by high N allocation for leaf carbon assimilation, high water use and photoinhibition avoidance, whereas the drought-tolerant evergreen was characterized by low N allocation for leaf carbon assimilation, conservative water use and photoinhibition tolerance.     

Transport,storage and mobilization of nitrogen by trees and shrubs in the wet/dry tropics of northern Australia

Xylem sap from woody species in the wet/dry tropics of northern Australia was analyzed for N compounds. At the peak of the dry season, arginine was the main N compound in sap of most species of woodlands and deciduous monsoon forest. In the wet season, a marked change occurred with amides becoming the main sap N constituents of most species. Species from an evergreen monsoon forest, with a permanent water source, transported amides in the dry season. In the dry season, nitrate accounted for 7 and 12% of total xylem sap N in species of deciduous and evergreen monsoon forests, respectively. In the wet season, the proportion of N present as nitrate increased to 22% in deciduous monsoon forest species. These results suggest that N is taken up and assimilated mainly in the wet season and that this newly assimilated N is mostly transported as amide-N (woodland species, monsoon forest species) and nitrate (monsoon forest species). Arginine is the form in which stored N is remobilized and transported by woodland and deciduous monsoon forest species in the dry season. Several proteins, which may represent bark storage proteins, were detected in inner bark tissue from a range of trees in the dry season, indicating that, although N uptake appears to be limited in the dry season, the many tree and shrub species that produce flowers, fruit or leaves in the dry season use stored N to support growth. Nitrogen characteristics of the studied species are discussed in relation to the tropical environment.     

中国不同地带性森林乔木叶片热值特征及其影响因素

[Objective]To study the leaf calorific value of different forest types.[Method]This study focused on four common forest types widely distributed across China, including boreal coniferous forest, warm temperate deciduous broad-leaved forest, subtropical evergreen broad-leaved forest, and tropical monsoon forest. The leaf calorific values of 175 dominant (or common) tree species were measured. The leaf calorific value characteristics of the trees found in the different forest types were analyzed, and the primary factors affecting leaf calorific value were investigated, including leaf morphological traits, nutrient elements, climate, and soil traits. [Result]The results showed that in these forest types, the leaf calorific values ranged from 14.84 to 21.98 KJ·g^-1, with an overall mean of 19.06 KJ·g^-1. The presence of organisms appeared to affect the leaf calorific value, which differed among forest types as follows: coniferous trees > broadleaf trees or evergreen trees > deciduous trees. [Conclusion]The latitudinal pattern of tree leaf calorific value, ordered from north to south, is as follows: warm temperate deciduous broad-leaved forest > subtropical evergreen broad-leaved forest > tropical mountain rainforest. The mean leaf calorific value of boreal coniferous forest was slightly lower than those of warm temperate deciduous broad-leaved forest and subtropical evergreen broad-leaved forest. The leaf calorific values were significantly correlated with leaf carbon content (R²= 0.89, P<0.001). A multiple regression equation was established to describe the relationships among leaf calorific value, leaf carbon content, leaf nitrogen content, and leaf thickness.     

中国南方天然常绿阔叶林枯叶分解的养分元素变化

中国南部的天然常绿阔叶林中,不同的初始条件下研究了栲树叶的重量损失和养分释放.对构成森林的13个树种的叶子也用枯叶袋法进行了研究.两年后栲树叶的分解率为53％～67％,其他13个种的叶分解率为59％～96％.两年间落叶树种叶子的重量损失大于常绿树种.分解叶的氮磷含有率随实验时间逐渐增加,而钾、钠、钙和镁的含有率却在降低.氮和磷的释放慢于更具活动性的元素,如钾、钠、钙和镁.分解率与最初的氮和磷的含有率成正相关.     

中国南部九连山常绿阔叶林的区系组成和林分结构

在中国南部的九连山研究了天然的和择伐过的常绿阔叶林的树种组成和林分结构.主要构成树种是常绿阔叶的栲树(Castanopsis fargesii)、罗浮栲(C.fabri)、甜槠栲(C.eyrei)、米槠栲(C.carlesii)、南岭栲(C.fordii)、鹿角栲(C.lamontii)和木荷(Schima superba).常绿针叶树种的马尾松(Pinus massoniana)和杉木(Cunninghamia lanceolata)也是主要成分.马尾松在坡脊和坡的上部占优势.许多落叶阔叶树种,如光皮桦(Betula luminifera)和拟赤杨(Alniphyllum fortunei)以较低的优势与常绿阔叶树种共同出现.它们补丁状分布在择伐过的林分中.种内的分布格局和种间的空间分布关系表明,主要构成种之间的空间集中分布地的分离是在一个小的尺度上.     

德兴不同类型常绿阔叶林土壤养分状况

以赣北常绿阔叶林的典型代表德兴大茅山林区为研究对象,比较不同林分类型下土壤养分状况。结果表明：1米槠＋甜槠林的林下土壤有机质含量最高,为3.1270%,马尾松＋木荷林有机质含量最低,为2.1887%;27种林分类型的N素均低于正常水平;3马尾松＋木荷林下土壤交换性盐基总量平均值最大,为米槠＋甜槠林中交换性盐基总量的2.11倍;4土壤养分各指标之间彼此均存在极显著的相关性。     

Seasonal variations of leaf traits and drought adaptation strategies of four common woody species in South Texas,USA

Understanding physiological responses and drought adaptation strategies of woody plant leaf traits in sub-humid to semi-arid regions is of vital importance to understand the interplay between ecological processes and plant resource-allocation strategies of different tree species.Seasonal variations of leaf morphological traits,stoichiometric traits and their relationships of two drought tolerant woody species,live oak(Quercus virginiana)and honey mesquite(Prosopis glandulosa)and two less drought tolerant species,sugarberry(Celtis laevigata)and white ash(Fraxinus americana)were analyzed in a sub-humid to semi-arid area of south Texas,USA.Our findings demonstrate that for the two drought tolerant species,the leguminous P.glandulosa had the highest specific leaf area,leaf N,P,and lowest leaf area and dry mass,indicating that P.glandulosa adapts to an arid habitat by decreasing leaf area,thus reducing water loss,reflecting a resource acquisition strategy.While the evergreen species Q.virginiana exhibited higher leaf dry mass,leaf dry matter content,C content,C:N,C:P and N:P ratios,adapts to an arid habitat through increased leaf thickness and thus reduced water loss,reflecting a resource conservation strategy in south Texas.For the two less drought tolerant deciduous species,the variations of leaf traits in C.laevigata and F.americana varied between Q.virginiana and P.glandulosa,reflecting a trade-off between rapid plant growth and nutrient maintenance in a semi-arid environment.