土壤是生态系统诸多生态过程的载体, 是植物赖以生存的环境条件。全球土壤有机碳(SOC)库约为25 000亿t, 接近生物碳库的4.5倍和大气碳库的3.3倍, SOC含量的小波动可能会影响生态系统的可持续性(Lal, 2004)。土壤氮(N)和磷(P)是陆地生态系统中限制植物生长和不同生物过程的最重要的营养物质。碳(C)、N和P作为土壤养分的重要组成元素, 不仅是探索土壤养分化学计量比空间分布的重要支撑, 还是自然生态系统中植物群落组成、演替和稳定的主要驱动因素(Tsunoda et al., 2014)。因此, 分析土壤C、N、P的化学计量特征及其影响因子, 有助于更好地认识养分有效性及其对植物生长的限制, 并为阐明C、N、P的循环过程与平衡机制提供关键信息(Mooshammer et al., 2014; 曾昭霞等, 2015)。
祁连山作为我国西北半干旱区内陆河流域重要的地表水资源形成区, 在涵养水源、水资源利用和整个西北地区的生态环境保护、经济社会的可持续发展等方面, 有着不可或缺的作用(马剑等, 2021)。高寒灌丛占祁连山总面积(25.9万km2)的17.57%, 占祁连山保护区林业用地面积的68%, 其有效蓄水量在3亿m3以上, 与云杉(Picea spp.)林相比是更大的“绿色水库”, 对祁连山的水土保持、生物多样性保护和生态系统安全极为重要。近些年来由于更加频繁的人类活动和气候变化, 灌丛生态系统遭受了较为严重的破坏, 部分地区出现退化状况, 生态服务功能明显下降(马剑等, 2021; 王小娜等, 2022)。然而目前关于该地区高寒灌丛土壤沿海拔梯度的养分限制状况及其与气候之间的关系方面的研究较少。
Nottingham等(2015)和Hu等(2016)指出热带森林中土壤SOC、全氮(TN)、全磷(TP)、速效氮和速效磷含量随海拔升高而增加。Shan等(2014)的研究表明森林土壤SOC、TN和速效氮含量与海拔高度无关。Müller等(2017)对尼泊尔地区高山林线交错带的土壤养分进行研究, 发现随海拔升高土壤N、P有效性和N:P、C:P下降, 而C:N呈增加趋势。高海宁等(2021)指出随着海拔升高土壤C、N、P含量在中海拔地区达到最高, 土壤C:P与C:N总体呈下降趋势。李丹维等(2017)对太白山阔叶林带的研究指出土壤C:N随海拔增高呈现降低趋势, N:P先上升后下降。谢锦等(2016)发现, 天山北坡土壤C:P和N:P随海拔上升均先增高后降低, 且随植被类型的变化而变化。基于此, 本研究作出假设: (1) SOC、TN含量随海拔上升先增加后降低, 土壤TP含量持续增加; (2)较高海拔处土壤N:P呈下降趋势, 植被生长主要受N限制; (3)土壤C:N:P化学计量特征受环境因子综合作用的影响。
1 材料和方法
1.1 样地概况
研究样地位于甘肃省肃南裕固族自治县祁连山中段的排露沟流域(38.53° N, 100.30° E), 海拔2 300-3 800 m, 流域面积2.71 km², 属大陆性高寒山地气候。过去30年的平均年降水量约416 mm (近80%的降水事件发生在5-10月), 年潜在蒸发量1 011.3 mm, 年平均气温0.4 ℃, 年日照时间1 562.6 h (Feng et al., 2022)。灌木层优势种有鬼箭锦鸡儿(Caragana jubata)、吉拉柳(Salix gilashanica)、金露梅(Potentilla fruticosa)等, 草本层主要有莎草、火绒草(Leontopodium leontopodioides)、珠芽蓼(Bistorta vivipara)等。
1.2 样品采集与测定
表1 排露沟流域不同海拔灌丛群落样地概况
Table 1
| 样地 Sampling plot | 海拔 Altitude (m) | 坡度 Slope (°) | 坡向 Slope aspect (°) | 生长季总降水量 Total precipitation of the growing season (mm) | 生长季平均气温 Mean air temperature of the growing season (℃) | 灌丛地上生物量(平均值±标准误) Aboveground biomass of shrublands (mean ± SE, g·m-2) |
|---|---|---|---|---|---|---|
| 1 | 3 100 | 21 | 27 | 425.05 | 9.80 | 41.61 ± 5.96 |
| 2 | 3 200 | 34 | 15 | 418.97 | 9.60 | 51.37 ± 3.92 |
| 3 | 3 300 | 36 | 9 | 411.47 | 8.83 | 73.20 ± 5.06 |
| 4 | 3 400 | 33 | 41 | 406.21 | 8.97 | 80.94 ± 12.15 |
| 5 | 3 500 | 36 | 56 | 388.11 | 8.26 | 75.98 ± 8.62 |
| 6 | 3 600 | 35 | 10 | 374.89 | 7.39 | 62.76 ± 5.40 |
| 7 | 3 700 | 33 | 34 | 358.00 | 6.99 | 44.23 ± 4.38 |
土壤样品经自然风干后去除枯叶、砾石等杂物, 研磨过100目筛。土壤pH利用pH仪测定, SOC含量采用重铬酸钾容量法测定。TN用H2SO4-K2SO4:CuSO4: Se催化法进行消煮, TP用H2O2-H2SO4法消煮, 消煮得到的溶液经定容、静置过夜和稀释后使用SmartChem200 (WestCo, Brookield, USA)化学分析仪测定含量。
1.3 数据处理
采用Excel 2019、SPSS 25、Origin 8.5软件对数据进行处理、统计分析并作图。对不同海拔和不同土层间的C、N、P含量及化学计量比采取双因素方差分析和最小显著差异(LSD)法多重比较, 运用Person相关分析对土壤C、N、P及化学计量特征和灌丛地上生物量、土壤pH及气候因子之间进行了相关性对比。
2 结果和分析
2.1 不同海拔土壤养分含量分布特征
排露沟流域各海拔灌丛0-10 cm层土壤SOC、TN、TP含量均高于10-20 cm层。SOC含量在0-10 cm土层为81.68-121.07 g·kg-1, 平均值为100.27 g·kg-1 (图1A); 在10-20 cm层为67.92-110.62 g·kg-1, 平均值86.45 g·kg-1 (图1G), 随海拔升高呈先增加后降低趋势, 于3 300 m处达到最高值。土壤TN含量在海拔梯度上表现出与SOC相似的分布规律, 0-10 cm层变化区间为6.72-9.27 g·kg-1, 平均值为7.95 g·kg-1 (图1B); 10-20 cm层为6.06-8.13 g·kg-1, 平均值6.96 g·kg-1 (图1H), 最高值出现在3 400 m高山灌丛处。土壤TP含量随海拔升高显著增加, 其中0-10 cm层为0.50-0.71 g·kg-1, 平均值0.59 g·kg-1 (图1C); 10-20 cm层为0.45-0.69 g·kg-1, 平均值0.55 g·kg-1 (图1I)。双因素方差分析(表2)表明, 海拔和土层均对土壤SOC、TN和TP含量有极显著影响, 但海拔与土层的交互效应对土壤养分含量无显著影响。
图1
图1
排露沟流域0-10 cm (A-F)和10-20 cm (G-L)土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量与计量比沿海拔梯度分布状况(平均值±标准误)。不同小写字母表示不同海拔高度的同一指标差异显著(p < 0.05)。
Fig. 1
Variations of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) contents and stoichiometry for the 0-10 cm (A-F) and 10-20 cm (G-L) soil layer across the altitude gradient (mean ± SE) in Pailugou watershed. Different lowercase letters indicate significant difference of the same indicator among different altitudes (p < 0.05).
表2 海拔和土层对排露沟流域土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量及化学计量特征的影响
Table 2
| 因素 Factor | SOC | TN | TP | SOC:TP | TN:TP | SOC:TN | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| F | p | F | p | F | p | F | p | F | p | F | p | |
| 土层 Soil layer | 38.143 | 0.000 | 51.785 | 0.000 | 24.710 | 0.000 | 12.338 | 0.002 | 6.329 | 0.018 | 0.426 | 0.519 |
| 海拔 Altitude | 24.538 | 0.000 | 21.395 | 0.000 | 48.513 | 0.000 | 113.000 | 0.000 | 52.962 | 0.000 | 11.022 | 0.000 |
| 土层×海拔 Soil layer × altitude | 0.377 | 0.887 | 0.899 | 0.509 | 0.411 | 0.865 | 0.695 | 0.656 | 0.408 | 0.868 | 1.025 | 0.430 |
加粗字体表示存在显著影响(p < 0.05)。
Bold font indicates significant impact (p < 0.05).
2.2 不同海拔土壤养分化学计量比分布特征
各海拔土壤C:N:P的垂直分布呈现随土层加深而减小的规律, C:P和N:P下降幅度较大, C:N的变化幅度较小, 各土层间差异不显著(p > 0.05)(表2)。土壤C:N在0-10 cm层为10.94-13.96、平均值为12.60 (图1F), 在10-20 cm层为10.93-14.63, 平均值12.42 (图1L), 且沿海拔升高总体呈下降趋势。土壤C:P随海拔升高先增加后降低, 在3 300 m高山灌丛处远高于其他海拔(图1D、1J), 主要是由SOC含量偏高所致。土壤N:P表现出与C:P相似的变化规律, 在0-10和10-20 cm层平均值分别为13.52、12.89, 且10-20 cm层土壤N:P在各海拔均小于16 (图1E、1K), 意味着该研究区深层土壤始终受N限制。经双因素方差分析(表2)表明, 土壤C:P、N:P和C:N均受海拔梯度的极显著影响; 土层对C:P和N:P也存在极显著影响, 但对C:N影响不明显; 土壤C:N:P化学计量特征不受土层和海拔交互效应的影响。
2.3 不同海拔土壤养分含量及化学计量比的相关性
各海拔0-10 cm和10-20 cm层土壤SOC与TN含量之间存在显著正相关关系(r = 0.54, p < 0.001; r = 0.33, p < 0.01)(图2A), 与TP含量呈显著负相关关系(r = -0.26, p < 0.01; r = -0.30, p < 0.01)(图2B), 而TN与TP之间的相关性不显著(图2C; 表3)。土壤C:P与TN含量呈正相关关系(r = 0.23, p < 0.05; r = 0.19, p < 0.05)(图2E), C:N与TP含量呈负相关关系(r = -0.45, p < 0.01; r = -0.23, p < 0.05)(图2F), N:P与SOC含量呈极显著正相关关系(r = 0.74, p < 0.001; r = 0.51, p < 0.001)(图2D; 表2)。表明祁连山灌丛土壤0-10 cm和10-20 cm层SOC、TN、TP在空间分布上相互耦合。
图2
图2
排露沟流域土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量及其化学计量比的相关性。虚线和实线分别代
Fig. 2
Correlations between soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) contents and their stoichiometry in Pailugou watershed. Dashed line and solid line represents the nutrient indicator fitting line of 0-10 cm and 10-20 cm, respectively.
表3 排露沟流域0-10 cm、10-20 cm层土壤养分化学计量特征和环境因子的相关分析
Table 3
| 土壤养分 Soil nutrient | 土层 Soil layer (cm) | SOC | TN | TP | SOC:TP | TN:TP | SOC:TN |
|---|---|---|---|---|---|---|---|
| TN | 0-10 | 0.734*** | |||||
| 10-20 | 0.570** | ||||||
| TP | 0-10 | -0.568** | -0.140 | ||||
| 10-20 | -0.581** | -0.277 | |||||
| SOC:TP | 0-10 | 0.901*** | 0.516* | -0.846*** | |||
| 10-20 | 0.911*** | 0.457* | -0.857*** | ||||
| TN:TP | 0-10 | 0.866*** | 0.746*** | -0.758*** | 0.915*** | ||
| 10-20 | 0.730*** | 0.728*** | -0.846*** | 0.864*** | |||
| SOC:TN | 0-10 | 0.591** | -0.065 | -0.684** | 0.755*** | 0.438* | |
| 10-20 | 0.734*** | -0.123 | -0.520* | 0.739*** | 0.305 | ||
| pH | 0-10 | 0.183 | -0.154 | -0.661** | 0.419 | 0.331 | 0.410 |
| 10-20 | 0.342 | 0.187 | -0.696*** | 0.561** | 0.601** | 0.259 | |
| 生长季总降水量 Total precipitation of the growing season | 0-10 | 0.660** | 0.271 | -0.943*** | 0.885*** | 0.798*** | 0.717*** |
| 10-20 | 0.666** | 0.280 | -0.957*** | 0.893*** | 0.823*** | 0.625** | |
| 生长季平均气温 Mean air temperature of the growing season | 0-10 | 0.600** | 0.202 | -0.929*** | 0.838*** | 0.742*** | 0.709*** |
| 10-20 | 0.581** | 0.250 | -0.933*** | 0.829*** | 0.792*** | 0.553** | |
| 灌丛地上生物量 Aboveground biomass of shrubs | 0-10 | 0.509* | 0.786*** | 0.064 | 0.245 | 0.452* | -0.201 |
| 10-20 | 0.383 | 0.590** | -0.042 | 0.214 | 0.338 | -0.060 |
*, p < 0.05; **, p < 0.01; ***, p < 0.001。SOC, 土壤有机碳含量; TN, 土壤全氮含量; TP, 土壤全磷含量。
*, p < 0.05; **, p < 0.01; ***, p < 0.001. SOC, soil organic carbon content; TN, soil total nitrogen content; TP, soil total phosphorus content。
2.4 不同海拔土壤养分化学计量特征与环境因子的相关性
环境因子与土壤C、N、P含量及化学计量特征的相关性分析(表3)表明生长季总降水量和平均气温均与SOC含量呈显著正相关关系, 与TP含量呈极显著负相关关系, 与TN含量则不存在相关关系。此外, 生长季总降水量和气温还与C:P、N:P呈极显著正相关关系, 与C:N的关系表现为在0-10 cm层呈极显著正相关关系, 在10-20 cm层呈显著正相关关系。
土壤pH与SOC、TN含量之间没有显著相关性, 与TP含量在0-10 cm土层呈显著负相关关系, 在10-20 cm层呈极显著负相关关系。此外, 10-20 cm层土壤pH与C:P和N:P之间存在显著正相关关系。灌丛地上生物量对表层土壤养分化学计量特征的影响强于深层土壤, 具体表现为在0-10 cm层与土壤SOC含量及N:P呈显著正相关关系, 与TN含量呈极显著正相关关系。在10-20 cm层, 灌丛地上生物量只与土壤TN含量呈显著正相关关系, 与其他指标不存在相关性。这也反映了土壤C、N、P的形成和储存的机制, 即SOC和TN含量主要与植被生长有关, 而TP主要受土壤性质的影响。
3 讨论
3.1 海拔对土壤C、N、P含量的影响
土壤养分的空间分布表现出一定的海拔梯度特征。本研究区灌丛土壤SOC、TN含量随海拔升高呈“单峰”趋势, 于中海拔段达到峰值, 和Zhang等(2019)和Xiao等(2019)研究结果类似, 这可能是土壤温度、湿度、微生物和植被等因素综合作用的结果。野外调查发现流域内中海拔段灌丛地上生物量远高于其他海拔, 植物凋落物及根系分泌物等有机质的输入能力增强, 土壤C、N的来源增多, 此外, 海拔升高, 降水量减少, 温度降低, 逐渐形成有利于土壤微生物生存的最适水热环境, 中海拔处较高的微生物生物量及活性提高了植被凋落物被分解的速率(Miki, 2012; Ren et al., 2018), 从而使该地区土壤具有相对丰富的C、N含量(He et al., 2016; 董廷发, 2021), 而低海拔地区土壤养分含量并不高, 可能是由于该区域较高的温度导致土壤微生物消耗了大量养分(Su et al., 2020)。高海拔地区的低温环境会影响水的黏度与膜的渗透性, 通常会抑制微生物的活性, 最终降低C和N的有效性(Reich & Oleksyn, 2004)。与SOC和TN相反, 随海拔上升TP在土壤中的含量持续增加, 表明高海拔地区能够比低海拔地区维持更多的P。一方面, 低海拔处的高降水量加剧了土壤P的流失, 不利于P储存。另一方面, 高海拔处较冷的温度和较低的降水量会导致微生物多样性与丰度的降低, 进而限制磷库的分解, 有助于土壤P的积聚(Tan & Wang, 2016; Zhang et al., 2019)。
各海拔灌丛土壤SOC、TN、TP含量都表现出随土层加深而减少的垂直分布特征, 与姜哲浩等(2019)对三江源区土壤养分的研究结果一致。这是因为表层土壤含有大量的腐殖质, 而且是植物根系分布集中区, 受外界环境因素及植被凋落物养分归还的影响, 养分在土壤表层聚集(张莎莎等, 2020), 同时, 植物生长对养分的吸收与富集作用也使得0-10 cm层土壤TN和TP含量更高。前人研究发现土壤深度增加导致的土壤密度变化也与土壤养分含量之间具有显著相关性(吴昊等, 2019)。土层加深, 土壤密度增大, 土壤板结程度也相应增强, 植物根系数量减少, 有机质积累量随之下降; 此外, 土层加深还会造成土壤孔隙度的减小, 以及通透性的下降, 进而导致参与分解有机质的微生物数量和活性降低(邱新彩等, 2018)。这些因素的共同作用使得研究区表层土壤C、N、P含量高于深层土壤。
3.2 海拔对土壤C:N:P化学计量特征的影响
C:N是氮矿化能力的标志, 可反映土壤有机质的分解状况。C:N与SOC分解速率成反比, 低C:N (<25)表明有机质分解速度大于积累速度, 土壤C释放, 进而导致土壤质量降低(Bui & Henderson, 2013)。该研究发现排露沟流域高海拔地区灌丛土壤C:N远低于中低海拔地区, 说明高海拔处的低温低降水等条件使得土壤肥力下降, 不利于植被的生长发育。土壤C:P和N:P随海拔上升均呈先增加后减小趋势, 和赵维俊等(2016)的研究结果一致, 这可能与酸性磷酸酶和低分子有机酸等根系分泌物有关, 它们可以使土壤酸化, 进而改变土壤养分的溶解。Hou等(2014)指出较低的C:P表明土壤在有机质分解过程中有释放磷的倾向, 促进土壤有效磷含量增加。该流域高海拔地区的C:P显著低于其他海拔, 意味着高海拔处土壤P含量相对丰富。N:P可用作养分限制阈值的诊断指标, 一般定义为N:P > 16时, P供应不足; N:P < 14时, N供应不足(Tessier & Raynal, 2003)。该研究发现3 400 m处0-10 cm层土壤N:P达到最大值(16.34 ± 0.37) g·kg-1, 表明中海拔地区对植物生长和养分循环的P限制最大; 此后呈现下降趋势, 这是因为高海拔处的低温可能会抑制有机质的矿化和分解作用, 从而降低N的有效性(Hobbie et al., 2000; Reich & Oleksyn, 2004), 同时也说明排露沟流域高寒灌丛在较高海拔处的N限制随海拔的升高而增强。此外, 该流域各海拔10-20 cm层土壤N:P始终低于0-10 cm层, 意味着深层土壤受N制约更为严重。
3.3 土壤C、N、P含量与化学计量比之间的相关性
3.4 土壤C:N:P化学计量特征与环境因子在海拔 梯度上的相关性
降水量、气温等气侯因子是制约土壤养分含量高低和影响土壤C、N、P化学计量比的重要因素(Famiglietti et al., 1998)。土壤P主要来自岩石风化作用(Jiang et al., 2019), 相比于SOC和TN, 受气候因子的影响更强。本研究结果显示生长季平均气温与土壤C:N、C:P和N:P之间均存在正相关关系, 这与Zhang等(2019)对长白山不同海拔土壤养分化学计量特征的研究结果有所区别, 他们的研究结果显示土壤温度与C:N显著负相关, 与C:P和N:P正相关, 这可能是受降水和土壤水分的影响(肖烨等, 2014)。土壤水分是土壤元素迁移与循环的重要载体, 可以直接影响土壤养分含量和植物生长。Aponte等(2010)研究发现, 较低的土壤含水率不利于植被生长, 土壤SOC的积累受到遏制, 从而导致高海拔地区的土壤C:N较低。另一方面, 在更高的降水和湿度条件下, 土壤风化严重, P从母质中快速释放并大量淋失造成土壤P浓度低, 从而使得中低海拔地区的C:P和N:P远高于较高海拔(Manzoni et al., 2010)。不同母质发育的土壤pH间具有显著差异(王珏等, 2022), 各土层土壤pH与TP含量呈显著正相关关系, 通过影响土壤P的来源和储存, 进而调控深层土壤C:P与N:P。土壤SOC和TN含量不受土壤pH的影响, 在0-10 cm层与灌丛地上生物量呈正相关关系, 这是因为土壤SOC、TN含量主要源于植被凋落物和根系分泌物等有机质的输入(Yu & Chi, 2020; Zhang et al., 2021), 但随土壤深度增加, 有机质的输入能力减小, 使得该研究区土壤SOC、TN含量与灌丛地上生物量的相关性沿土层加深而减弱。研究区各海拔10- 20 cm层土壤N:P均小于16, 意味着灌丛生长始终受N的制约, 故其地上生物量与深层土壤TN含量之间仍存在显著相关性, 而与SOC含量不相关。土壤P是一种沉积元素, 其含量主要受成土母质的影响(Jiang et al., 2019), 因而灌丛地上生物量在各土层间均与TP含量无相关性。除以上因素外, 土壤C、N、P生态化学计量特征还受到人类活动、坡度、坡向及植被类型等多种因素的影响, 可在今后进行更加深入地探究。
4 结论
研究发现, 祁连山排露沟流域土壤C、N、P含量及化学计量特征在海拔梯度上变化显著。随着海拔升高, 各土层土壤SOC、TN含量均先增后降, TP含量则一直增加。C:P和N:P在中海拔处达到最高值, 表明中海拔地区对植物生长和养分循环的P限制最大, C:N随海拔升高总体呈下降趋势反映了土壤质量的降低。各海拔土壤养分聚集在土壤表层, C:P和N:P随土壤深度增加而减小, C:N在土层间变化不明显。土壤SOC、TN和TP含量与C:N:P之间普遍存在相关性, 说明排露沟流域灌丛土壤的养分之间存在一定的耦合机制。灌丛地上生物量与TP含量间不存在相关关系, 在0-10 cm层和土壤SOC、TN含量呈正相关关系, 土壤pH仅与TP含量呈显著负相关关系, 反映了土壤C、N、P形成和储存的机制, 即SOC、TN含量主要与植被生长有关, 而TP主要受土壤性质的影响。除TN外, 土壤SOC含量、TP含量和C:N:P均受降水量、气温的显著影响。
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DOI:10.17521/cjpe.2015.0065
[本文引用: 1]
探明我国西南喀斯特生态脆弱区植被恢复重建背景下, 森林植物、凋落物与土壤碳(C)、氮(N)、磷(P)化学计量特征有助于深入地认识喀斯特森林生态系统养分循环规律和系统稳定机制。该文选取桂西北典型喀斯特地区域3个原生林群落和3个自然恢复28年的次生林群落, 研究其“植物-凋落物-土壤”连续体的C、N、P化学计量学特征及其内在关联。结果表明: 1)圆果化香树(Platycarya longipes)、伞花木(Eurycorymbus cavaleriei)和青檀(Pteroceltis tatarinowii)以及圆叶乌桕(Sapium rotundifolium)、八角枫(Alangium chinense)和黄荆(Vitex negundo) 6种植物的C、N、P平均含量分别为427.5、21.2、1.2 mg·g<sup>-1</sup>; 凋落物C、N、P平均含量分别为396.2、12.7、0.9 mg·g<sup>-1</sup>, 而表层土壤(0-10 cm) C、N、P平均含量分别为92.0、6.35和1.5 mg·g<sup>-1</sup>。2)原生林N再吸收率(平均值为42.7%)高于次生林(平均值为36.5%), P再吸收率(20.4%)显著低于次生林(32.3%) (p < 0.05); 6个森林群落N的再吸收率均大于P的再吸收率。3)不同群落凋落物的C:N值差异不显著, 原生林植物的C:N值小于次生林、土壤C:N显著大于次生林; 原生林土壤C:P与次生林无显著差异, 植物与凋落物C:P小于次生林; 原生林凋落物与土壤N:P值小于次生林, 植物N:P比平均值均为17.4。4)研究区典型森林群落植物中N和P含量呈显著的正相关关系, 植物C:N与N:P、C:P与N:P比值均无明显相关关系; 经过对数变换后的土壤C:N与N:P呈显著负相关关系, 凋落物的C:P与N:P值呈极显著正相关关系。研究结果可为我国西南典型喀斯特脆弱生态区的生态功能恢复与植被重建提供科学依据。
Spatial pattern of C:N:P stoichiometry characteristics of alpine grassland in the Altunshan Nature Reserve at North Qinghai-Tibet Plateau
DOI:10.1016/j.catena.2021. 105691 [本文引用: 1]
Soil stoichiometry characteristics at different elevation gradients of a mountain in an area with high frequency debris flow: a case study in Xiaojiang Watershed, Yunnan
泥石流频发区山地不同海拔土壤化学计量特征——以云南省小江流域为例
Ecological stoichiometry of soil carbon, nitrogen and phosphorus in Cunninghamia lanceolata plantation across an elevation gradient
不同海拔杉木人工林土壤碳氮磷生态化学计量特征
Linkages of C:N:P stoichiometry between soil and leaf and their response to climatic factors along altitudinal gradients
DOI:10.1007/s11368-018-2173-2
[本文引用: 3]
Purpose Altitudinal gradients have been recognized as a natural experiment to assess the structure and functions of above - and below-ground ecosystem under global climate change. Nutrient stoichiometry is tightly linked both the above- and below-ground functioning, but how the altitudinal gradients affect nutrient stoichiometry among plant and soil systems remains unclear. Materials and methods Soil samples were collected at 17 sites along an altitudinal gradient from 1362 to 3320m in the North Slope of Taibai Mountain. These samples represent three different climate zones, including a warm temperate zone, a cold temperate zone, and an alpine cold zone. Soil moisture (SM), soil temperature (ST), and the concentrations of carbon (C), nitrogen (N), and phosphorus (P) in soil and leaves were determined. Results and discussion The C and N in soil and leaves were higher at medium altitudes than that at low or high altitudes, while P concentrations increased significantly as altitude increased. The C: N ratio in soil and leaves was not significantly affected by altitudinal gradients, but the C: P and N: P ratios were lower at high altitudes. In particular, the leaf N:P ratio at high altitudes was less than 12, suggesting an increase in N limitation along altitudinal gradients. Moreover, except the C: N ratio, soil C: N: P stoichiometry was significantly related to leaf C: N: P stoichiometry, and both showed closed relationships with ST and SM. Conclusions These results suggest that stoichiometric characteristics appear to be closely linked with climatic factors, and improved knowledge of C: N: P stoichiometry patterns along altitudinal gradients will be indispensable to a comprehensive understanding of the influences of climate change on ecosystems.
Ecological stoichiometric characteristics of carbon, nitrogen and phosphorus in leaf- litter-soil system of Picea crassifolia forest in the Qilian Mountains
祁连山青海云杉林叶片-枯落物-土壤的碳氮磷生态化学计量特征
