Features on N/P ratio of plants with different functional groups between two types of steppe in semi-arid area

The differences in nitrogen/phosphorus(N/P)ratios of different functional groups in ecology are more helpful in explaining species competition and community dynamics.Based on the functional groups of plant growth type,carbon metabolism pathway,root type and phylogenetic type,we analyzed characteristics of leaf N/P ratios of 77 species in Sanggendalai(typical grassland zone)of Zhenglan Banner,Inner Mongolia,China and 91 species in the Habahu National Nature Reserve(desertified grassland zone)in Yanchi County of Ningxia,China.The results show that the N/P ratio(16.91)of C3 plants in the desertified steppe was significantly larger than that(12.72)in the typical steppe,but there was no significant difference between the N/P ratios of C4 plants in the two zones.There was no significant difference in N/P ratios between C3 plants and C4 plants in the same zone.Similarly,the N/P ratio(16.60)of dicotyledons in desertified steppe were significantly higher than that(12.98)in typical steppe,while differences in N/P ratios between monocotyledonous plants of the two zones was not significant,and there existed no significant difference in N/P ratios between dicotyledonous and monocotyledonous plants in the same zone.The N/P ratio had significant difference between gramineous and non-gramineous plants in the typical steppe but not in the desertified steppe,but there existed no significant difference in N/P ratios among different root types of perennial herbaceous plants in the same type of steppe or between two types of steppe.Thus,different features on the N/P ratios of C3 plants and dicotyledonous plants between typical steppe and desertified steppe may lead to different growth status of plants,and the N/P ratio stoichiometric of the same plant functional group may be a foundation of the changes of a plant community.

Species-area relationship within and across functional groups at alpine grasslands on the northern Tibetan Plateau,China

The species-area relationship （SAR） is one of the most fundamental concepts in community ecology and is helpful for biodiversity conservation. However, few studies have systematically addressed this topic for different alpine grassland types on the Tibetan Plateau, China. We explored whether the plant composition of different functional groups affects the manner in which species richness inereases with increasing area at scales ≤ 1.0 m^2. We also compared species richness （S） within and across forbs, legumes, sedges and grasses, with sampling subplot area （A） increasing from 0.0625 m^2 to 1.0 m^2 between alpine meadow and steppe communities. We applied a logarithmic function （S = b0 ＋ b1 ln A） to determine the slope and intercept of SAR curves within and across functional groups. The results showed that the logarithmic relationship holds true between species richness and sampling area at these small scales. Both the intercept and slope of the logarithmic forbs-area curves are significantly higher than those for the three other functional groups （P 〈 0.05）. Forb accounts for about 91.9 % of the variation in the intercept and 75.0% of the variation in the slope of the SAR curve when all functional groups＇ data were pooled together. Our results indicated that the different SAR patterns should be linked with species dispersal capabilities, environmental filtering, and life form composition within alpine grassland communities. Further studies on the relationship between species diversity and ecosystem functions should specify the differential responses of different functional groups to variations in climate and anthropogenic disturbances.

Leaf N and P stoichiometry of 57 plant species in the Karamori Mountain Ungulate Nature Reserve,Xinjiang,China

Nitrogen （N） and phosphorus （P） are the major nutrients that constrain plant growth and development, as well as the structure and function of ecosystems. Hence, leaf N and P patterns can contribute to a deep understanding of plant nutrient status, nutrient limitation type of ecosystems, plant life-history strategy and differentiation of functional groups. However, the status and pattern of leaf N and P stoichiometry in N-deficiency desert ecosystems remain unclear. Under this context, the leaf samples from 57 plant species in the Karamori Mountain Ungulate Nature Reserve, eastern Junggar Desert, China were investigated and the patterns and interrelations of leaf N and P were comparatively analyzed. The results showed that the average leaf N concentration, P concentration, and N：P ratio were 30.81 mg/g, 1.77 mg/g and 17.72, respectively. This study found that the leaf N concentration and N：P ratio were significantly higher than those of studies conducted at global, national and regional scales; however, the leaf P concentration was at moderate level. Leaf N concentration was allometrically correlated with leaf P and N：P ratio across all species. Leaf N, P concentrations and N：P ratio differed to a certain extent among plant functional groups. C4 plants and shrubs, particularly shrubs with assimilative branches, showed an obviously lower P concentration than those of C3 plants, herbs and shrubs without assimilative branches. Shrubs with assimilative branches also had lower N concentration. Fabaceae plants had the highest leaf N, P concentrations （as well as Asteraceae） and N：P ratio; other families had a similar N, P-stoichiometry. The soil in this study was characterized by a lack of N （total N：P ratio was 0.605）, but had high N availability compared with P （i.e. the available N：P ratio was 1.86）. This might explain why plant leaves had high N concentration （leaf N：P ratio〉16）. In conclusion, the desert plants in the extreme environment in this study have formed their intrinsic and special stoichiometric characteristics in relation to their life-history strategy.

Uptake and Recovery of Soil Nitrogen by Bryophytes and Vascular Plants in an Alpine Meadow

Due to their particular physiology and life history traits, bryophytes are critical in regulating biogeochemical cycles and functions in alpine ecosystem. Hence, it is crucial to investigate their nutrient utilization strategies in comparison with vascular plants and understand their responses to the variation of growing season caused by climate change. Firstly, this study testified whether or not bryophytes can absorb nitrogen(N) directly from soil through spiking three chemical forms of 15N stable isotope tracer. Secondly, with stronger ability of carbohydrates assimilation and photosynthesis, it is supposed that N utilization efficiency of vascular plants is significantly higher than that of bryophytes. However, the recovery of soil N by bryophytes can still compete with vascular plants due to their greater phytomass. Thirdly, resource acquisition may be varied from the change of growing season, during which N pulse can be manipulated with 15N tracer addition at different time. Both of bryophytes and vascular plants contain more N in a longer growing season, and prefer inorganic over organic N. Bryophytes assimilate more NH4+ than NO3– and amino acid, which can be indicated from the greater shoot excess 15N of bryophytes. However, vascular plants prefer to absorb NO3– for their developed root systems and vascular tissue. Concerning the uptake of three forms N by bryophytes, there is significant difference between two manipulated lengths of growing season. Furthermore, the capacity of bryophytes to tolerate N-pollution may be lower than currently appreciated, which indicates the effect of climate change on asynchronous variation of soil N pools with plant requirements.

Variations in the Volatile Organic Compound Emission Potential of Plant Functional Groups in the Temperate Grassland Vegetation of Inner Mongolia, China

Abstract: The biogenic volatile organic compounds (VOC) emitted by the vegetation of a terrestrial ecosystem play a key role in both regional air quality and tropospheric chemistry. To describe the general emission properties of VOC of different plant functional groups (PFG) in a typical temperate grassland in Inner Mongolia, China, we randomly selected 175 plant species and measured the quantities of isoprene and monoterpene in situ. Results showed that most plants had low VOC emission potential at the species level, especially for some dominant plants, such as Leymus chinensis Tzvel., Stipa grandis Smirn., and Agropyron cristatum Gaertn. At the PFG level, the lowest VOC emission potential was found for perennial rhizome grasses, a major PFG in a typical temperate grassland ecosystem. The effects of overgrazing and subsequent vegetation succession on the emission of VOC by different plant life form functional groups (PLFG) were also discussed.

Plant functional groups mediate effects of climate and soil factors on species richness and community biomass in grasslands of Mongolian Plateau

Aims Functional group composition of a plant community is mainly driven by environmental factors and is one of the main determinants of grassland biodiversity and productivity.Therefore,it is important to understand the role of plant functional groups(PFGs)in mediating the impact of environmental conditions on ecosystem functions and biodiversity.Methods We measured plant biomass and species richness(SR)of grasslands in 65 sites on the Mongolian Plateau and classified 157 perennial herbaceous plants into two main PFGs(namely grasses and forbs).Using the random forest model and ordinary least squares regression,we identified that environmental factors(i.e.aridity index,soil total nitrogen[STN]and pH)were significantly related to the SR and aboveground biomass(AGB)of PFGs.We then used structural equation modeling to explore the relationship between the identified environmental factors and community SR and biomass,and the role of PFGs in driving this relationship.Important Findings We found that aridity index had unimodal relationships with both AGB and SR of the PFGs and the whole community.All SR and biomass metrics were significantly related to STN and pH.The relationship between aridity index and community biomass was mediated by an increase in the AGB of grasses.The influence of STN and pH on community SR was mainly due to their regulation in the SR of forbs.Our results indicate that community composition and the identity of the PFGs play a key role in linking environmental factors to ecosystem functioning.

Relationship between Plant Species Diversity and Plant Biomass of Orchard Grass and Lucerne Sown in Different Ratios in the Province of Salamanca, Spain

A field experiment was carried out at the CSIC Mu&#241ovela farm belonging to the Spanish National Research Council (CSIC) in order to evaluate the effect of sowing orchard grass (Dactylis glomerata var. Trerano) and lucerne (Medicago sativa var. Aragon) in monoculture and in combination. The experiment was based on a randomized block designed with a factorial arrangement (5 × 2). Experimental units were 40 plots distributed in four blocks. The phosphorus fertilization (P) factor included two types of conditions: basal fertilization without phosphorus (-P) and basal fertilization with phosphorus (+P), and the vegetation cover factor (T) included five conditions depending on the grass (G) and the legume (L). Above-ground biomass showed statistically significant differences among seasons and years (P Lolium perenne L. and Poa pratensis L. throughout the three years indicated that both species significantly increased their presence over time regardless of the treatments applied. The analysis performed for the other plant species (those other than grasses and legumes) allowed us to determine that the T1 and T5 treatments, which correspond to single species not treated with the application of phosphorus, influenced the presence of 70% of other species planted. Our specific aim was to explore how changing plant biotic diversity affects productivity under a given set of conditions. We manipulated plant species richness as an experimental factor to determine if productivity would be affected by changes in the ratios of plants sown.

基于植物功能群的生态系统服务形成与维持机制研究

生态系统可以从“结构-功能-服务”3个层次来理解,其中服务是人类的主观感受或效用。维持高质量的生态系统服务还需从生态系统的自然属性入手。结构和功能是生态系统服务形成和维持的内在机制,而植物是生态系统结构和功能的核心驱动力。植物功能群具有特定功能的植物组合,其中优势植物功能群控制着生态系统的结构和功能。生态系统服务的概念、分类与植物功能群密切相关,植物功能群是生态系统与生态系统服务间更直接的桥梁。建立生态系统服务与植物功能群间的联系,使相关研究有更明确的指向,在深化理论研究的同时使研究成果更容易落地。生态系统服务的形成、维持机制与植物功能群的内在联系主要体现在4个主要方面:(1)植物功能群的内在适应性特征和外在效应是生态系统服务形成的基础;(2)植物功能群的多功能特性为生态系统服务协同提供了可能;(3)植物功能群间替代和互补效应可以提升生态系统服务质量和稳定性;(4)植物功能群能够提供基于自然的生态系统服务修复问题解决方案。

甘南高寒草甸退化对植物功能群物种多样性与物种多度分布的影响

【目的】探究甘南高寒草甸植物功能群多样性及其物种多度分布对退化的响应,分析随退化程度的加深不同植物功能群的群落构建机理及资源利用方式。【方法】研究以甘南高寒草甸为对象,采用样地调查法收集数据,使用物种多度模型对其进行拟合分析,并采用双向聚类分析对群落物种进行分类。【结果】随着退化程度的加深,植被优势种以禾本科和莎草科植物为主,逐渐变为杂类草功能群植物为主,杂类草功能群在群落多样性分布中起主导作用;全部物种多度分布随着退化程度的加深发生变化,其中,无退化草甸的最优拟合模型是VOLKOV,轻度退化草甸的最优拟合模型是GEO,中度退化草甸和重度退化草甸的最优拟合模型为BRO,资源分配模式由随机分配转向固定分配的分配模式;禾草功能群的最优拟合模型以生态位模型为主,资源分配方式由固定分配和随机分配共同主导,豆科功能群的最优拟合模型是BRO,资源分配方式以固定分配为主,杂类草功能群的最优拟合模型从中性模型向生态位模型转变,与全部物种多度分布的最优模型基本一致,且资源分配由随机分配向固定分配转变。【结论】杂类草功能群是影响群落物种多度分布的主要原因,但是禾草和豆科功能群的贡献也不可忽视。

牦牛和藏羊放牧对青藏高原高寒草地植物群落氮库的影响

放牧是青藏高原高寒草地最主要的利用方式,牦牛和藏羊是青藏高原最常见的放牧家畜,家畜通过采食植物地上部分会使地上生物量减少,进而对植物群落氮库产生影响。本研究依托青海省高寒草地-家畜系统适应性管理技术平台的放牧试验样地,探讨不同家畜类型放牧对高寒草地植物群落氮库的影响。研究结果表明:未放牧处理下高寒草地地上生物量为180.0 g·m^(-2),藏羊单独放牧显著降低了植物群落地上生物量。对未放牧处理下不同功能群氮素含量的研究发现:豆科植物(26.4 mg·g^(-1))>杂类草(17.0 mg·g^(-1))>禾草(12.9 mg·g^(-1))≈莎草(11.8 mg·g^(-1))。放牧显著增加了禾草和莎草氮含量,对杂类草氮含量影响较小。放牧对群落水平植物地上部分氮含量的影响变化小于对各功能群的变化影响,因为植物群落具有稳定性。当高寒草地植物群落处于放牧压力下,会从土壤中获取更多的氮以维持生长,放牧会进一步加剧青藏高原高寒草地植物生长的氮限制。

绿肥种植密度对咖啡幼龄园杂草群落及咖啡生长的影响

绿肥种植是一种比较理想的杂草控制技术,通过田间试验研究了绿肥硬皮豆不同种植密度对咖啡幼龄园杂草群落和咖啡生长的影响。绿肥种植5月后,对5种硬皮豆种植密度〔S0、S1、S2、S3、S4分别为0、0.5、1.0、1.5、2.0 kg·(667 m^(2))^(-1)〕的杂草群落和咖啡生长情况开展调查。结果表明,随着硬皮豆种植密度的增加,优势杂草香附子重要值显著降低,杂草群落及优势杂草香附子的高度、密度、盖度及生物量均低于对照S0。随着硬皮豆种植密度增加,杂草群落Margalef丰富度指数、Shannon-Wiener多样性指数先降低后增加,Simpson优势度指数逐渐降低,Pielou均匀度指数逐渐增加。硬皮豆种植处理下杂草群落高度、密度、盖度及生物量的响应比均显著低于对照S0,硬皮豆种植显著降低了Simpson优势度指数的响应比,显著提高了Pielou均匀度指数的响应比。功能群分类中禾本科的重要值表现为S2和S3处理显著高于对照S0,其余功能群的重要值差异不显著。杂草功能群分类的重要值与群落多样性指数间相关性不显著。硬皮豆种植后咖啡植株的株高、冠幅、地径、叶长、叶宽、一级分枝对数、最长一级分枝长、最长一级分枝节间数及叶片厚度均高于对照S0,其中叶宽差异达显著水平。整体上,硬皮豆种植在一定程度上促进了咖啡植株生长,对杂草群落及优势杂草香附子具有显著的控制效果,显著降低了杂草群落优势度,短期内对杂草群落丰富度及多样性无影响。咖啡幼龄园种植硬皮豆建议采用种植密度1.0 kg·(667 m^(2))^(-1),可获得较高的经济效益和生态效益。

青藏高原高寒草甸地上植物功能群去除对土壤线虫群落的影响

土壤线虫对高寒草甸生态系统功能有重要的指示作用,植物功能群丧失对土壤线虫群落的影响尚不清楚。本研究在青藏高原东部的高寒草甸生态系统中设置对照、保留豆科、保留禾状草、保留非豆科杂类草和去除所有植物功能群5个处理的地上部植物功能群去除实验,以探究植物功能群损失对土壤线虫群落的影响。结果显示:(1)去除植物功能群地上部对植物根系生物量和土壤线虫总密度影响不显著。(2)去除植物功能群地上部对线虫不同营养类群相对丰度影响显著。保留豆科处理下,食细菌线虫相对丰度整体最高,而植物寄生线虫相对丰度最低;保留杂类草处理下,植物寄生线虫相对丰度整体最高,而食细菌线虫相对丰度最低。(3)非度量多维尺度分析(NMDS)结果表明,去除不同植物功能群会导致土壤线虫类群产生差异,对土壤线虫群落结构产生显著影响。

不同种植模式对苹果园昆虫群落多样性与稳定性的影响

为明确不同种植模式对苹果园昆虫群落多样性与稳定性的影响。2022年6-12月于昭通苹果主产区的间作大豆Glycine max、间作紫花苜蓿Medicago sativa、自然生草3种种植模式苹果园中,采用植株调查、网捕调查、黄盘诱集、黄板诱集、食诱剂诱集6种调查方法进行调查。3种种植模式苹果园中共调查到昆虫316850头,隶属于12目82科189种。双翅目昆虫的物种数和个体数量最多,个体数量占3种果园中调查总个体数量的77%以上,其中优势类群为果蝇科Drosophilidae、蛾蚋科Psychodidae、眼蕈蚊科Sciaridae。3种植模式苹果园中性类群、植食类群、寄生类群的物种组成聚类中,间作大豆果园与间作紫花苜蓿果园均聚为一类;间作紫花苜蓿果园中捕食类群和植食类群的生态位宽度指数更高,分别为17.8401和12.7612,植食类群的生态位宽度指数更低,为10.2868,间作大豆果园中捕食类群和寄生类群的生态位重叠指数为0.7398,较其余果园更低。中性类群的辛普森指数、香农—维纳指数、均匀度,捕食类群的辛普森指数、均匀度,寄生类群的香农—维纳指数均为间作大豆果园和间作紫花苜蓿果园高于自然生草果园;间作紫花苜蓿果园较其余果园Ss/Si波动更小,7月和10月Sa/Sp值更高。本研究明确了双翅目为昭通苹果园中的优势类群,间作大豆苹果园和间作紫花苜蓿苹果园物种组成更为相似,较自然生草果园群落多样性更好,其中间作紫花苜蓿苹果园昆虫群落稳定性最高,研究结果在一定程度上可为苹果园害虫的生态防控提供借鉴。

高寒草甸植物生态化学计量特征的空间格局及其影响因素

植物碳(C)、氮(N)、磷(P)含量及其生态化学计量比反映了植物对环境变化的适应。然而,目前关于不同植物功能群如何调节C、N、P含量及其生态化学计量比以适应海拔梯度的变化还不清楚。在青藏高原东南缘高寒草甸选取了60个样点,对不同功能群(禾本科、莎草科、豆科和杂类草)C、N、P含量及其生态化学计量比(质量比)沿着海拔梯度(3300—3500 m、3500—3700 m、3700—3900 m、3900—4100 m和4100—4300 m)的变化规律及其关键驱动因子进行研究。结果表明:1)不同植物功能群具有一定的生态化学计量学内稳性,各功能群C含量,莎草科和豆科N含量,禾本科、莎草科和杂类草P含量,以及除莎草科C∶P之外的不同功能群C∶P和N∶P随海拔升高变化不显著(P>0.05)。2)禾本科和杂类草植物通过增加N含量适应高海拔环境,即海拔3900—4100和4100—4300 m它们的N含量显著高于其他海拔。4100—4300 m豆科植物P含量显著低于3700—3900 m(P<0.05)是由年平均降水量下降引起的。3)4个功能群C∶N整体上随着海拔增加而下降,表明海拔升高引起植物N素利用效率下降;同时,各植物功能群N∶P均大于16,植物生长受P限制。4)与非豆科植物相比,豆科植物N含量和N∶P高,而C含量和C∶N低。5)冗余分析(RDA)和结构方程模型(SEM)表明,海拔和纬度共同驱动的年平均气温和降水量变化是调控不同植物功能群C、N、P含量及其生态化学计量比的关键因子。综上,海拔梯度上,植物具有增加、降低或保持自身C、N、P含量及其生态化学计量比稳定的生态适应性策略,这种差异因植物功能群的不同而异,因此在构建植物C、N、P生物地球化学模型中应考虑海拔梯度上植物生态适应性策略的差异。

不同补播模式对荒漠草原植物群落特征及土壤养分的影响

为了解补播对荒漠草原草地植被恢复的影响及作用,在短花针茅(Stipa breviflora)荒漠草原开展了围封补播试验,设置5个处理,分别为对照(补播机械不加种子作业一次,CK)、单播新麦草(Psathyrostachys juncea,XX)、单播冰草(Agropyron cristatum,BB)、单播黄花苜蓿(Medicago falcata,HH)以及混播新麦草、冰草、黄花苜蓿(BXH),于植物生长季(8月)进行植物群落调查,并对土壤以及植物进行取样分析。结果表明,补播能够显著提高植物地上生物量,且单播新麦草处理有显著影响(P<0.05)。补播对多年生杂类草高度、密度有抑制作用,使Margalef丰富度指数有所升高,而使Shannon-Wiener多样性指数和Pielou均匀度指数下降,但均无显著影响,并且补播处理下土壤养分无显著变化。在植物群落特征指标与土壤养分指标相关性分析中发现,植物平均高度和盖度是影响植物地上生物量的显著因子,土壤全磷含量对植物高度影响显著,且土壤全氮含量与土壤全磷含量显著正相关(P<0.05)。结果初步表明补播措施对于荒漠草原草地植被以及土壤的改善具有积极意义,可为后续补播对荒漠草原草地的影响研究提供参考。

氮磷添加对内蒙古温带草原植物功能群氮含量的影响

植物功能群氮含量既是理解氮沉降对生物多样性影响的关键指标,也是生产力过程模型模拟的重要参数,极易受氮素可利用性的影响和磷元素的限制。基于内蒙古温带草原4年氮磷添加试验(N10、N40、P5、P10及其交互,数字代表添加剂量,单位为g m^(-2) a^(-1)),分析氮磷添加对植物群落及三种植物功能群(禾本科、灌木和杂类草)氮含量的影响。结果表明:(1)氮添加显著增加了群落及各功能群的氮含量,同一处理水平下禾本科(N10)和灌木(N10和N40)的氮含量显著高于杂类草,同一功能群不同氮添加剂量间无显著差异;(2)磷添加对群落和三种功能群的氮含量无显著影响;(3)与单独氮添加相比,氮磷同时添加显著增加了群落、禾本科和杂类草氮含量,且高剂量氮磷添加的促进作用更大;(4)与单独氮添加相比,氮磷同时添加显著增加群落和三种功能群磷含量而降低氮磷比,相同处理水平下禾本科和杂类草磷含量增加幅度最大。本研究将为草原生态系统管理和应对全球变化提供科学依据。

藏北高寒天然草地常见牧草营养品质影响因素分析

为探究草地管理方式、土壤养分、气候条件、群落结构对不同功能群植物营养品质的相对影响,2020年夏在藏北羌塘地区的高寒草原与荒漠草原选取样地进行植物和土壤采样。结果表明:(1)高寒草原区牧草粗蛋白含量显著高于荒漠草原区,而粗脂肪含量显著低于荒漠草原区(P<0.05);放牧管理显著提高了高寒草原区牧草的粗蛋白含量(P<0.05);(2)高寒牧草的粗脂肪含量随生长季降雨增加而降低(P<0.01);中性洗涤纤维含量随生长季温度升高而增加(P<0.05);(3)牧草的粗脂肪含量随土壤有机碳含量的增加而降低(P<0.05),酸性洗涤纤维和纤维素含量随土壤有机碳含量的增加而增加(P<0.05)。综上所述,藏北高寒草地常见牧草营养品质主要受气候条件、土壤养分和草地管理方式的多重调控。因此,建议未来通过优化草地管理、调控土壤养分有效性来改善藏北天然高寒草地常见牧草的营养品质。

青藏高原高寒草地不同植物功能群与土壤碳同位素特征及影响因素

青藏高原海拔高、面积广,是全球范围内最典型的高寒地区之一,探究青藏高原高寒草地植物和土壤碳稳定同位素组成(δ^(13)C)特征及其控制要素,对深刻理解高寒生态系统碳循环过程具有重要意义。研究采集并测定了青藏高原不同区域135个草地样点中的植物和土壤碳稳定同位素自然丰度,探讨了不同植物功能群和表层(0—10 cm)土壤δ^(13)C特征及其与气候、土壤因素的关系。结果表明:(1)杂类草δ^(13)C显著低于禾本科、莎草科和豆科植物δ^(13)C(P<0.05)。表层土壤δ^(13)C与禾本科、莎草科、豆科植物δ^(13)C呈显著正相关(P<0.05),与杂类草δ^(13)C无显著相关关系,且表层土壤δ^(13)C对三种植物功能群δ^(13)C的敏感性为禾本科>豆科>莎草科。(2)在影响禾本科、莎草科、豆科植物和表层土壤δ^(13)C的环境因子中,气候因子的相对贡献率均大于土壤因子,气候因子中太阳辐射相对贡献率最大,杂类草δ^(13)C与气候和土壤因子均不存在显著相关关系。研究表明,太阳辐射是决定高寒草地生态系统植物和表层土壤δ^(13)C的主要因子。研究可为青藏高原高寒草地植物和土壤δ^(13)C特征与有机碳动态循环提供数据支撑和理论参考。

贵州北盘江流域观赏兰科植物及其功能群研究

为科学保护和合理开发贵州北盘江流域野生兰科(Orchidaceae)植物资源,科学筛选高观赏价值兰科植物并探究其环境适应特征,该文以贵州省北盘江流域分布的兰科植物为研究对象,基于层次分析法筛选出具有较高观赏价值的种类,并使用聚类和冗余分析明确不同环境条件下的植物功能群物种组成。结果表明:(1)研究区兰科植物共74属249种(含变种),在水平空间分布上有2个密集区,分别是望谟县与紫云县交界片区和盘州市西部片区;在垂直空间分布上,随海拔变化呈“中间膨胀型”分布,以800~1 600 m范围为主。(2)研究区观赏兰科植物可划分为三大等级,第一级为开发优等级,共51种兰科植物,第二级为开发储备级,共170种,第三级的28种观赏价值较低,没有作为观赏植物开发的必要。(3)研究区开发优等级的观赏兰科植物可划分为低海拔喜荫非石灰岩山地功能群、低海拔喜阳石灰岩山地功能群、中海拔喜荫石灰岩山地功能群和高海拔喜阳非石灰岩山地功能群4类,不同功能群间兰科植物适应环境类型差异较大。综上表明,对贵州北盘江流域观赏兰科植物的筛选和生态功能群的划分,为今后园林应用、科学保护、引种驯化开发、野外回归等研究提供了一定参考价值。

Leaf nitrogen and phosphorus are more sensitive to environmental factors in dicots than in monocots,globally

Leaf nitrogen(N)and phosphorus(P)levels provide critical strategies for plant adaptions to changing environments.However,it is unclear whether leaf N and P levels of different plant functional groups(e.g.,monocots and dicots)respond to environmental gradients in a generalizable pattern.Here,we used a global database of leaf N and P to determine whether monocots and dicots might have evolved contrasting strategies to balance N and P in response to changes in climate and soil nutrient availability.Specifically,we characterized global patterns of leaf N,P and N/P ratio in monocots and dicots,and explored the sensitivity of stoichiometry to environment factors in these plants.Our results indicate that leaf N and P levels responded to environmental factors differently in monocots than in dicots.In dicots,variations of leaf N,P and N/P ratio were significantly correlated to temperature and precipitation.In monocots,leaf N/P ratio was not significantly affected by temperature or precipitation.This indicates that leaf N,P and N/P ratio are less sensitive to environmental dynamics in monocots.We also found that in both monocots and dicots N/P ratios are associated with the availability of soil total P rather than soil total N,indicating that P limitation on plant growth is pervasive globally.In addition,there were significant phylogenetic signals for leaf N(λ=0.65),P(λ=0.57)and N/P ratio(λ=0.46)in dicots,however,only significant phylogenetic signals for leaf P in monocots.Taken together,our findings indicate that monocots exhibit a“conservative”strategy(high stoichiometric homeostasis and weak phylogenetic signals in stoichiometry)to maintain their growth in stressful conditions with lower water and soil nutrients.In contrast,dicots exhibit lower stoichiometric homeostasis in changing environments because of their wide climate-soil niches and significant phylogenetic signals in stoichiometry.