微尺度下烟田铁的空间变异性及其与烟叶铁的相关分析

铁是作物必需的营养元素之一,是血红蛋白和细胞色素的组成成分,也是细胞色素氧化酶、过氧化氢酶、过氧化物酶等的组成成分,与烟叶香气前体物的形成密切相关.精准农业通常研究的是微尺度下(米级或亚米级)土壤养分的空间变异性.为此,在米级尺度下(11 m×10 m)对烟田全铁在种烟前后的空间变异性进行比较,并分析相应网格上烤后烟叶样品的铁含量,探讨土壤在种烟前后全铁含量与烟叶铁含量间的相互关系.结果表明:收完烟后试验地全铁含量平均值与种烟前相比有所下降,由30.3 g kg-1降到了24.79 g kg-1.种烟前土壤全铁具有中等的空间相关性(块金效应为48.8%),变异函数的最佳理论模型为线性模型,决定系数达到0.999,Block-Kriging内插图显示试验地全铁具有较强的空间异质性,方差分析的结果也表明取样点间的差异达极显著水平(p=0.00008).种烟后土壤全铁含量以球状模型为变异函数的最佳理论模型,决定系数达到0.956,Block-Kriging内插图显示种烟后土壤全铁含量的最高值比种烟前往南移动了一些,最低值也往北移了一些,整个试验地土壤全铁在种烟后的空间变异性比种烟前有所升高.相关分析表明,烟叶铁含量只与种烟前土壤全铁含量呈极显著相关,与种烟后土壤全铁含量、种烟前后土壤全铁的相对变化量都没有显著相关.根据相关分析的结果,建立了以种烟前土壤全铁含量为自变量,以烟叶全铁含量为因变量的回归方程,并对方程进行验证,结果表明在自变量X的分布区间内预测效果比较好.     

青藏高原草地植物群落冠层叶片氮磷化学计量学分析

叶片氮(N)和磷(P)的化学计量学研究涉及到植物生态学的众多领域与多个尺度, 然而各个尺度上的化学计量学研究并未同步展开。通过对青藏高原47个草地样地连续3年的调查, 分析了当地群落水平上的植物叶片N、P含量及其化学计量学特征, 并结合温度和降水气候数据研究了N、P含量及N:P比值与这两个气候因子的相关关系。研究结果显示: 青藏高原草地群落水平的叶片N含量变化范围为14.8-36.7 mg·g^-1, 平均为23.2 mg·g^-1; P含量变化范围为0.8-2.8 mg·g^-1, 平均为1.7 mg·g^-1; N:P比值变化范围为6.8-25.6, 平均为13.5。群落叶片N含量与P含量呈显著正相关关系, 叶片的N:P比值与P含量呈显著负相关关系, N:P比值的变化主要由P含量变化决定。另外发现: 群落水平叶片N、P含量及N:P比值存在着显著的年际变化, 叶片的N、P含量及N:P比值与年平均气温之间存在着极显著的相关关系。通过该研究结果推测: P含量较高的变异系数及其与环境因子表现出的显著相关性, 在一定程度上体现了植物群落对当地气候条件的一种适应。     

区县域尺度土壤全氮的空间分布格局分析

以赤峰市敖汉旗为研究对象,以实测数据为基础,采用地统计学与典范对应分析相结合的方法研究县域尺度土壤全氮的空间分布格局及其影响因素。结果表明:0—100 cm深度土壤全氮含量在0.43—0.68 g/kg范围变化,土壤全氮平均含量随着土壤深度的增加而降低,其水平分布均呈现为南高北低的分布特征,低值区集中呈片状分布在研究区的东北部,高值区呈岛状分散于研究区的南部区域。各层土壤全氮均属于中等强度的空间相关性,随着土壤深度的增加,随机因素对全氮空间变异的影响作用逐渐减弱,其空间最大自相关距离也随着土壤深度的增加而逐渐减小。各环境因素对土壤全氮含量的影响程度由高到低表现为海拔>NDVI>粘粒含量>土壤容重>坡度,土壤粘粒和NDVI与表层土壤的相关性更高,海拔对60 cm以下土壤全氮的影响更加显著。     

Spatial characterization of arbuscular mycorrhizal fungal molecular diversity at the submetre scale in a temperate grassland

Although arbuscular mycorrhizal fungi (AMF) form spatially complex communities in terrestrial ecosystems, the scales at which this diversity manifests itself is poorly understood. This information is critical to the understanding of the role of AMF in plant community composition. We examined small-scale (submetre) variability of AMF community composition (terminal restriction fragment length polymorphism fingerprinting) and abundance (extraradical hyphal lengths) in two 1 m(2) plots situated in a native grassland ecosystem of western Montana. Extraradical AMF hyphal lengths varied greatly between samples (14-89 m g soil(-1)) and exhibited spatial structure at scales <30 cm. The composition of AMF communities was also found to exhibit significant spatial autocorrelation, with correlogram analyses suggesting patchiness at scales <50 cm. Supportive of overall AMF community composition analyses, individual AMF ribotypes corresponding to specific phylogenetic groups exhibited distinct spatial autocorrelation. Our results demonstrate that AMF diversity and abundance can be spatially structured at scales of <1 m. Such small-scale heterogeneity in the soil suggests that establishing seedlings may be exposed to very different, location dependent AMF communities. Our results also have direct implications for representative sampling of AMF communities in the field.     

不同群落蒙古栎种群空间格局的地统计学分析

以蒙古栎天然次生林中的蒙古栎种群为研究对象,在吉林省汪清林业局塔子沟林场设置2块1 hm^2的处于不同演替阶段的样地(A、B).采用相邻网格调查法将每块样地划分为100个10 m×10 m的调查单元,对单元内每株林木的空间坐标进行精确定位,调查所有胸径≥1 cm的林木基本信息.采用地统计学分析的半方差函数法和分维数对蒙古栎种群各林木属性的空间异质性程度、组成、尺度、方向进行分析;运用克里格插值法对具有空间自相关的树木属性进行无偏估计并绘制分布图,分析其空间分布格局.结果表明:两块样地各林木属性的最优半方差函数以指数模型和球状模型为主,呈聚集分布,但样地A较样地B的空间自相关程度更高,空间连续性更大;两块样地内部,胸径和东西冠幅均表现出较强的空间异质性和空间自相关性.两块样地各林木属性均在南北方向上表现出较强的空间异质性.此外,样地A在西北-东南方向上也存在较强的空间异质性,而样地B则在东北-西南方向存在较强的空间异质性.两者相比,样地A的空间异质性强度更高、尺度更大.样地A中胸径和东西冠幅变异明显,而样地B中东西冠幅和南北冠幅变异明显.分维数值反映的结果与标准半方差函数值的结果基本一致.样地A各林木属性变量以斑块状和条带状分布为主,空间分布格局和变化趋势明显,而样地B各林木属性变量分布破碎,格局复杂.上述结果说明,种群属性特征、群落发育程度、空间尺度大小和空间水平方向可能影响种群的空间格局.基于地统计学的分析方法有助于定量、直观地描述种群的生长现状和发展趋势,可为东北林区大面积的蒙古栎天然次生林的可持续经营提供理论基础.     

烤烟糖含量的空间变异特征

以中国烤烟(Nicotiana tabacum)主产省份2005年B2F(上部二级桔黄色烤烟)、C3F(中部三级桔黄色烤烟)和X2F(下部二级桔黄色烤烟)3个等级烤烟为研究对象,利用地统计学与GIS技术结合的方法研究了中国烤烟主产省份烤烟水溶性总糖、还原糖含量和糖碱比的空间分布特征。结果表明:各等级烤烟水溶性总糖、还原糖含量和糖碱比空间相关性表现为近似相关,东西方向上,均呈现由西向东先降低后升高的趋势,南北方向上,水溶性总糖含量、还原糖含量趋势不明显,糖碱比各等级趋势各异。     

快速城市化地区昆明市“城—郊—乡”梯度土壤表 层碳氮磷化学计量特征

基于航空遥感影像,利用地理信息系统(ArcGIS 10.2)和景观格局分析(Fragstats 4.2)软件,通过主成分分析(PCA)和多元线性回归分析对研究区城市化水平进行量化,选取覆盖研究区典型的“城—郊—乡”样带,进行表层土壤取样,测定总有机碳(C)、全氮(N)、全磷(P)的含量并分析其空间变化特征。结果表明:快速的城市化进程导致了土壤C、N、P化学计量特征的空间分异,“城—郊—乡”梯度上变异系数都较大,尤其城区各元素的变异系数分别为84.08%、76.95%和81.34%,属于强变异,表明土壤表层C、N、P含量空间分布极不均衡。研究区土壤C、N、P含量均表现为城区显著高于郊区的特征,与郊区土壤相比,城区土壤C含量较高,说明人为活动造成城区土壤明显的有机质富集现象。城区土壤P含量高于郊区和乡村,城市化过程加剧了城区土壤P的富集,也使该地区水体(主要是滇池)面临富营养化风险。分析城市化过程中强烈的人类活动干扰对土壤C、N、P含量及其化学计量特征,对于提高城市土壤管理水平、改善生态环境、促进城市生态系统健康持续发展具有重要意义。今后昆明市在进行城市绿化时可有针对性地选择部分豆科固氮植物加强生物固氮,目的是提高土壤N含量的同时促进城区土壤丰富的P被吸收利用,在一定程度上预防以及减轻P对水体的危害。     

Spatial pattern analysis of entomopathogenic and other free‐living nematodes at landscape scales

Spatial patterns of entomopathogenic and other free‐living nematode populations were analyzed at the landscape scale. Free‐living bacterial feeder populations can be classified into trophic groups based on their functional and life history characteristics. Differences in life history traits were hypothesized to result in different spatial structures of populations. Spatial autocorrelations (Moran's I index) and exponential variogram models were calculated and estimated for each trophic group, including entomopathogenic nematodes, and comparisons were made among them. Spatial autocorrelation results showed that the spatial structure of entomopathogenic nematode populations is similar to that of relatively r‐selected free‐living bacterial feeders, which share several life history traits with entomopathogenic nematodes.     

麦红吸浆虫及其卵寄生蜂混合种群空间格局

运用地统计学方法对不同时期麦红吸浆虫及其卵寄生蜂混合种群(宽腹姬小蜂和尖腹黑蜂)的空间格局进行了分析.结果表明:麦红吸浆虫休眠体的半变异函数的最优模型为球型,成虫的最优模型为球型-指数型,幼虫最优模型为线性有基台型,卵寄生蜂混合种群半变异函数的最优模型为球型-指数型.麦红吸浆虫休眠体、成虫羽化初期、成虫羽化高峰期、幼虫和卵寄生蜂混合种群的空间相关范围分别为53.6、190.6、154.1、4.2和280.3 m,空间变异强度分别为30.5%、95.6%、96.3%、14.9%和95.3%.采用普通克立格插值法模拟的空间分布模拟图可较好地从时间、空间两个角度直观地分析不同时期麦红吸浆虫及其卵寄生蜂混合种群的动态变化.     

Green and senescent leaf phenolics showed spatial autocorrelation in a Quercus robur population in northwestern Spain

Intraspecific variation in polyphenols may be important both for the resistance of plants to herbivory and for nutrient cycling in terrestrial ecosystems. The spatial pattern and scale of polyphenol concentration in natural populations are practically unknown, despite multiple evidence that resources influencing leaf phenolics (such as light or nutrient availability) show spatial dependence at the scale of meters to tens of meters. By using geostatistical methods, we evaluated the spatial variability in polyphenol concentration in green and senescent leaves in a pedunculate oak (Quercus robur L.) population of 125 individuals. The spatial pattern of light and nutrient availability for plants was also evaluated. Leaf polyphenols were more variable than other leaf properties, and green polyphenols were significantly correlated with radiation, leaf mass per unit area and leaf N concentration. Both green and senescent leaf polyphenol concentration showed spatial dependence at distances below 6 to 10 m, with structural (spatial) variance explaining between 50 and 80% of the total variance. The variance not explained by space was assumed to be due to individual genotypic variability. Stochastic maps of leaf phenolics in the area showed that the probability of finding high phenolics level was not random. These findings may be important to understand the spatial heterogeneity of plant-herbivore interactions, leaf litter decomposition and mineralization rate.     

内蒙古草地叶片磷含量与土壤有效磷的关系

植物体内特别是叶片的P含量特征及其与环境的关系一直是植物生理生态学研究的一个热点。已有研究发现, 与全球植物数据相比, 中国植物叶片的P含量相对较低, 导致N/P高于全球平均水平, 并推测这是由于中国土壤全P含量较低引起的。该研究选取内蒙古草地来验证这一假设, 分析了36个样地57种优势植物叶片的P含量与土壤全P和有效P含量的关系。主要结果如下: 内蒙古草地叶片P含量较低而N/P较高, 与之前的研究结论一致; 在种群、样地和物种3个水平上, 叶片P含量、N/P与土壤P含量都没有显著的相关关系, 尽管土壤有效P含量的解释力高于土壤全P; 另一方面, 内蒙古草地土壤的有效P含量与全国土壤普查的结果接近, 高于美国及澳大利亚的平均值, 但低于世界土壤信息库里报道的全球土壤有效P平均值。鉴于内蒙古草地土壤的全P和有效P含量都不能准确反映叶片P含量, 且土壤的有效P含量也并不明显低于世界其他地区, 因此植物叶片P含量低、N/P高是由于土壤P含量低引起的这一假设在内蒙古草地不成立, 而且叶片P含量也与土壤P的可利用性无关。     

Elevated UV-B radiation incident on Quercus robur leaf canopies enhances decomposition of resulting leaf litter in soil

We examined whether the exposure of Quercus robur L. to elevated UV-B radiation (280–315 nm) during growth would influence leaf decomposition rate through effects on litter quality. Saplings were exposed for eight months at an outdoor facility in the UK to a 30% elevation above the ambient level of erythemally weighted UV-B radiation under UV-B treatment arrays of fluorescent lamps filtered with cellulose diacetate, which transmitted both UV-B and UV-A (315–400 nm) radiation. Saplings were exposed to elevated UV-A alone under control arrays of lamps filtered with polyester and to ambient radiation under unenergised arrays of lamps. Abscised leaves from saplings were enclosed in 1 mm² mesh nylon bags, placed in a Quercus–Fraxinus woodland and were sampled at 0.11, 0.53, 1.10 and 1.33 years for dry weight loss, chemical composition and saprotrophic fungal colonization. At abscission, litters from UV-A control arrays had ≈ 7.5% higher lignin/nitrogen ratios than those from UV-B treatment and ambient arrays (P < 0.06). Dry weight loss of leaves treated with elevated UV-B radiation during growth was 2.5% and 5% greater than that of leaves from UV-A control arrays at 0.53 and 1.33 years, respectively. Litter samples from UV-B treatment arrays lost more nitrogen and phosphorus than samples from ambient arrays and more carbon than samples from UV-A control arrays. The annual fractional weight loss of litter from UV-B treatment arrays was 8% and 6% greater than that of litter from UV-A control and ambient arrays, respectively. Regression analyses indicated that the increased decomposition rate of UV-B treated litters was associated with enhanced colonization of leaves by basidiomycete fungi, the most active members of the soil fungal community, and that the frequency of these fungi was negatively associated with the initial lignin/nitrogen ratio of leaves.     

Dominant roles but distinct effects of groundwater depth on regulating leaf and fine-root N,P and N:P ratios of plant communities

地下水位对植物群落叶片与细根氮磷化学计量特征的调控作用不同但影响显著 地下水作为干旱区水资源可利用性的决定因素,在调节植被分布和生态系统过程中具有至关重要的作用。尽管近年来在环境胁迫与群落水平性状的关系方面取得了较大的研究进展,但对于干旱区地下水变化所引起的水分胁迫如何影响植物群落水平化学计量比仍知之甚少。本研究的目的是评估植物群落地上地下部分化学计量比对地下水变化的不同响应。我们通过对典型干旱内陆河流域的110个样方进行调查,测定叶片和细根的氮磷含量,利用生物量加权法计算其化学计量比,并试图探究沿地下水位梯度,群落水平的化学计量比的变化模式及其关键驱动因素。研究结果表明,在群落水平上,地下水、植被类型以及物种组成是影响叶片与细根氮、磷与氮磷比的主要因素,其中地下水位起着主导性作用。地下水的作用主要表现为间接作用,其主要通过调控植被类型和物种组成来影响群落水平的氮磷化学计量比。植被类型和物种组成均对群落水平的氮磷化学计量比具有显著的直接作用。此外,在群落水平上,地下水对叶片与细根氮磷化学计量比的作用不同。地下水通过影响植被类型进而降低叶片氮、磷含量,以及增加叶片氮磷比与细根氮含量。地下水通过影响物种组成进而增加细根磷含量,降低细根氮磷比。综上所述,地下水而不是气候有效的调控了群落水平的氮磷化学计量比。此外,植物群落地上地下部分氮磷化学计量比对地下水位变化具有不同的响应。     

黄土丘陵区小流域土壤碳氮磷生态化学计量特征的空间变异性

土壤碳、氮、磷是植物重要的营养来源和保障生态系统健康的重要生态因子,其含量及化学计量比的动态平衡对生态系统的生产力具有重要影响,分析土壤碳、氮、磷养分含量及化学计量比的空间变异性和影响机制,对区域土壤养分管理以及土地可持续利用具有重要意义。本研究选取位于黄土高原东缘的三眼井小流域,利用经典统计与地统计相结合的方法,分析了研究区表层土壤(0～20 cm)有机碳(SOC)、全氮(TN)和全磷(TP)以及土壤碳氮磷的化学计量比的空间变异性和影响机制。结果表明:(1)研究区表层土壤SOC、TN和TP的平均值分别为3.97、0.83和0.6 g·kg-1,C∶N、C∶P、N∶P的平均值分别为4.73、6.02、1.26,均属于中等变异水平。(2)土地利用类型和地貌类型对研究区土壤SOC、TN具有显著影响,林地和荒草地高于梯田和退耕地,梁上高于沟谷; TP主要受土地利用类型的显著影响,梯田显著高于其他三种土地利用类型;土地利用类型对土壤C∶N、C∶P和N∶P的影响较为一致,表现为梯田显著低于其他土地利用类型; C∶N还受到坡度和地貌类型的显著影响,C∶P和N∶P还分别受到坡度和海拔的显著影响。(3...     

桂西北喀斯特洼地土壤有机碳和速效磷的空间变异

空间变异性的研究有助于认识土壤养分的空间分布特征与生态过程之间的关系。采用网格取样(20m×20m),利用地统计学方法分析了典型喀斯特洼地土壤有机碳(SOC)和速效磷(AP)的空间变异特征。结果表明SOC和AP的半变异函数分别用球状模型和指数模型拟合的效果较好。块金效应对SOC和AP总变异的贡献分别为37.9%和49.8%,说明SOC主要受结构性因素控制,而AP受结构性因素和随机因素双重控制。SOC的分布呈明显的带状各向异性特征,在洼地的长轴方向具有较大的变程和较小的基台值,其全向半变异函数的相关距离为135.5m,与洼地不同种植类型地块的覆盖尺度基本相当。AP的分布特征与SOC存在明显差异,具有较大的漂移趋势,其相关距离为413.4m;但在分离漂移趋势后,其相关距离为167.4m,反映了不同地块间的施肥差异对AP的影响较大。喀斯特洼地SOC的空间分布主要受地形和土地利用结构控制,而AP的分布的规律性不明显,可能与施肥等因素的随机性较强有关。     

区域尺度上栓皮栎叶性状变异及其与气候因子的关系

叶片在长期进化过程中对环境变化敏感且对气候变化的响应表现出表型可塑性。栓皮栎(Quercus varaibilis)是亚洲大陆地理分布最广泛的树种之一,横跨温带和亚热带地区。本文在中国中东部区域内,选取了25个天然栓皮栎林种群,测量了其叶柄长度、叶片长度、叶片宽度、叶片面积、叶片干重等,并计算了比叶面积和叶形指数(叶片长宽比)等叶性状特征,探讨了区域尺度上叶片性状变异与气候因子关系的格局。结果表明,栓皮栎叶片性状在种群间和种群内均存在显著的变异;叶片宽度与年均温度呈显著的负相关,叶片宽度和叶片面积与纬度均呈显著正相关,说明叶宽及叶片面积相对于其他指标对气候因子的影响变化更敏感,并且在这一区域尺度上温度影响着叶片大小的变异格局。本研究结果为在全球气候变化背景下了解区域尺度上栓皮栎对环境变化的适应与响应机制提供了基础。     

Leaf P increase outpaces leaf N in an Inner Mongolia grassland over 27 years

The dynamics of leaf nitrogen (N) and phosphorus (P) have been intensively explored in short-term experiments, but rarely at longer timescales. Here, we investigated leaf N : P stoichiometry over a 27-year interval in an Inner Mongolia grassland by comparing leaf N : P concentration of 2006 with that of 1979. Across 80 species, both leaf N and P increased, but the increase in leaf N lagged behind that of leaf P, leading to a significant decrease in the N : P ratio. These changes in leaf N : P stoichiometry varied among functional groups. For leaf N, grasses increased, woody species tended to increase, whereas forbs showed no change. Unlike leaf N, leaf P of grasses and forbs increased, whereas woody species showed no change. Such changes may reflect N deposition and P release induced by soil acidification over the past decades. The interannual effect of precipitation may somewhat have reduced the soil available N, leading to the more modest increase of leaf N than of leaf P. Thus, leaf N : P stoichiometry significantly responded to long-term environmental changes in this temperate steppe, but different functional groups responded differently. Our results indicate that conclusions of plant stoichiometry under short-term N fertilization should be treated with caution when extrapolating to longer timescales.