黄土丘陵区草地土壤微生物C、N及呼吸熵对植被恢复的响应

以野外样地调查和室内分析法研究了黄土丘陵区不同植被恢复年限下草地土壤微生物C、N及土壤呼吸熵的变化.结果表明,土壤微生物量碳明显地随着植被恢复年限的增加而增加.在恢复前23a, 土壤微生物量碳在0～20 cm土层年增加率为24.1%;20～40 cm为104.4%.植被恢复23a后,0～20 cm土层增长率为0.83%,20～40 cm为0.19%.土壤微生物量N表现为在植被恢复的初期略有下降,3a后,开始出现明显增加.0～20 cm土层年增长率为20.14%,20～40 cm为15.11%.在植被恢复23a后,0～20 cm土层的年增长率为0.14%,20～40 cm变化不大.土壤微生物呼吸强度随着恢复年限的增加逐渐加强;土壤呼吸熵随植被封育时间的增加而呈对数降低趋势.土壤呼吸熵(qCO2)在反映土壤的生物质量变化时,显得更加稳定,受植物生长状况影响较小.相关分析表明,土壤微生物量和土壤微生物活性与土壤有机质、碱解氮和粘粒含量显著正相关;与土壤粉粒含量明显负相关;表层土壤pH值对其也有明显影响.草地植被自然恢复过程可增加土壤微生物活性,有利于土壤质量的提高.     

农业土地利用方式对华北平原土壤有机碳组分和团聚体稳定性的影响

作为土壤质量的重要指标,土壤有机碳及其组分在土壤许多物理、化学和生物特性中发挥着重要作用。以在华北平原具有代表性的禹城市作为研究区域,系统研究和分析了该地区不同农业土地利用对土壤有机碳组分和团聚体稳定性的影响。结果表明：与传统小麦．玉米轮作的粮田相比,果树和苜蓿栽培明显增加了土壤总有机碳（TOC）和总氯（TN）含量,同时也显著提高了土壤易氧化有机碳（EOC）、颗粒有机碳（POC）、轻组有机碳（LFOC）和水溶性有机碳（WSOC）含量和分配比例。果园土壤微生物生物量C（MBC）和可矿化碳（MNC）较传统粮田的土壤分别增加了34．0．5％和66．3％。果树栽培还明显增加了土壤〉250μm水稳性团聚体（WSA）的含量,同时减少了土壤粘粒分散率（CDR）。苜蓿栽培也显著提高了土壤MBC和MNC含量以及团聚体稳定性。温室大棚栽培前期（2-3a）的土壤TOC和TN较传统粮田略有增加,但随着耕作历史的增加,土壤TOC和TN呈现逐年下降的趋势。与传统粮田相比,温室大棚内的土壤LOC,POC,LFOC和WSOC含量与比例均有明显下降,这种下降幅度随栽培历史的延长而明显增加。7-10a温室大棚栽培的土壤EOC,POC,LFOC和WSOC含量较传统粮田分别下降了31．3％,41．7％,35．6％和42．1％。温室大棚栽培的土壤MBC和MNC较传统粮田的土壤平均分别低15．9％和10．1％。温室大棚栽培,特别是长期栽培降低了土壤中〉250μm水稳性团聚体的含量和粘粒的稳定性。相关分析表明,土壤〉250vm水稳性团聚体的含量与所测定的有机碳组分含量皆成明显的正相关,特别是POC,LFOC和MBC与WSA达到极显著相关,相关系数分别为0．912,0．893,0．856。这表明,土壤POC,LFOC和MBC对维持土壤团聚体稳定性具有更为重要意义。     

Effects of Revegetation on Soil Microbial Biomass,Enzyme Activities,and Nutrient Cycling on the Loess Plateau in China

Revegetation is a traditional practice widely used for soil and water conservation on the Loess Plateau in China. However, there has been a lack of reports on soil microbial–biochemical indices required for a comprehensive evaluation of the success of revegetation systems. In this study, we examined the effects of revegetation on major soil nutrients and microbial–biochemical properties in an artificial alfalfa grassland, an enclosed natural grassland, and an artificial shrubland (Caragana korshinskii), with an abandoned cropland as control. Results showed that at 0–5, 5–20, and 20–40 cm depths, soil organic carbon, alkaline extractable nitrogen and available potassium were higher in natural grassland and artificial shrubland compared with artificial grassland and abandoned cropland. Soil microbial biomass C (Cmic) and phosphorous (Pmic) substantially decreased with depth at all sites, and in abandoned cropland was significantly lower than those of natural grassland, artificial grassland, and artificial shrubland at the depth of 0–5 cm. Soil microbial biomass N (Nmic) was higher in artificial shrubland and abandoned cropland compared with that in natural and artificial grasslands. Both Cmic and Pmic were significantly different between the 23‐year‐old and the 13‐year‐old artificial shrublands at the 0–5 cm depth. The activities of soil invertase, urease, and alkaline phosphatase in natural grassland and artificial shrubland were higher than those in artificial grassland and abandoned cropland. This study demonstrated that the regeneration of both natural grassland and artificial shrubland effectively preserved and enhanced soil microbial biomass and major nutrient cycling, thus is an ecologically beneficial practice for recovery of degraded soils on the Loess Plateau.     

黄土丘陵区恢复草地土壤团聚体组成及全氮分布特征

团聚体作为土壤基本结构单元,其各粒级全氮（TN）含量对土壤TN储量的贡献各不相同,而草地恢复过程中地上植被会影响土壤团聚体组成与各粒级TN的分布,这必然会对团聚体稳定性和土壤氮素累积产生影响。因此,以恢复10a、20a、30a、40a和50a草地和对照农田（CK）为研究对象,探究草地恢复过程中土壤团聚体氮素累积规律。结果表明：1）50年恢复过程中草地群落经历了茵陈蒿（Artemisia capillaries）→茵陈蒿+铁杆蒿（Artemisia stechmanniana）→铁杆蒿+兴安胡枝子（Lespedeza davurica）→铁杆蒿+本氏针茅（Stipa bungeanaTrin）→铁杆蒿+白羊草（Bothriochloa ischaemum）的演替过程,且草地群落物种多样性指数随恢复年限的增加呈先升后降的趋势,地上植物、细根和凋落物的碳和氮含量呈先上升后下降趋势。2）草地恢复过程中土壤pH和容重呈下降趋势,而土壤含水量呈先降后增趋势,土壤有机碳含量在恢复过程中显著增加（P<0.05）,土壤TN含量随恢复年限呈先增后降的趋势,而TN储量呈逐年增加趋势,恢复10-50a草地与CK相比增加了8.10%-118.92%。3）不同恢复年限草地群落土壤微团聚体（0.053-0.25 mm）占比最大,但随恢复年限增加呈下降趋势,而大团聚体（>2 mm）和中团聚体（0.25-2 mm）占比以及平均重量直径（MWD）和几何平均直径（GMD）呈上升趋势。4）不同恢复年限草地群落中团聚体TN含量最高,且各粒级团聚体TN含量随恢复年限呈先下降后上升趋势;草地群落微团聚体TN储量最高,大、中团聚体TN储量随恢复年限增加呈上升趋势,微、粘粉粒团聚体（<0.053 mm） TN储量随恢复年限增加出现波动;各粒级团聚体TN储量与地上植物、细根和凋落物生物量以及碳氮含量显著相关（P<0.05）。5）草地恢复过程中大团聚体对土壤TN储量的贡献率达70%,且大团聚体占比增加是大团聚体贡献率高的主要原因。总之,草地恢复有利于土壤稳定以及氮素累积。     

不同施肥模式对潮土有机碳组分及团聚体稳定性的影响

作为土壤质量的重要指标,土壤有机碳及其组分在土壤许多物理、化学和生物特性中发挥着重要作用。在田间条件下,通过对7种肥料结构组合处理下的土壤进行采样和分析,系统地研究和比较了不同养分模式对华北平原潮土土壤有机碳组分和土壤团聚体稳定性的影响。结果表明。与单施化肥处理（NPK）比较,NPK＋S和NPK＋M处理显著增加土壤耕作层（0～20cm）的总有机碳（TOC）和总氮（TN）含量。PK和CK处理的土壤TOC和TN较试验前土壤皆有明显下降。有机无机肥配施,明显增加土壤易氧化有机碳（EOC）、颗粒有机碳（POC）、轻组有机碳（LFOC）和水溶性有机碳（WSOC）。特别是与NPK处理相比较,NPK＋M处理的土壤EOC、POC、LFOC和WSOC含量分别增加23．8％、39．9％、42．5％和32．1％。土壤耕作层中微生物生物量碳（MBC）和可矿化碳（MNC）以有机无机肥配施为最高,NPK处理次之,PK处理和CK最小。有机无机肥配施处理还明显增加了土壤〉250μm水稳性团聚体（WSA）含量,并降低了土壤粘粒分散率（CDR）。相关分析表明,土壤〉250μm水稳性团聚体（WSA）含量与所测定的有机碳组分含量皆呈明显正相关,特别是POC、LFOC和MBC与WSA达到极显著相关．相关系数分别为0.89、0.81和0,78;CDR与TOC、POC和LFOC皆呈显著负相关,相关系数分别为-0．70、-0．78和-0．73。     

Nitrogen released from different plant residues of the Loess Plateau and their additions on contents of microbial biomass carbon, nitrogen in soil

An incubation method was used to investigate the nitrogen release characteristics from the residue of ten plant species which commonly grow in the northern part of the Loess Plateau. The effect of the residue on soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) was also determined. There were significant differences in the total N content and the C/N ratios among the different types of plant residue. The total N content of the residues ranged from 6.61 to 32.78 g kg^?1. The C/N ratio of the residue ranged from 14 to 65. There was an immediate increase in soil N after alfalfa, erect milkvetch, and korshinsk peashrub residue was added to the soil. In contrast, soil N decreased after elm, sea buckthorn, and wild peach residue was added to the soil. The soil N content remained relatively low for 14–34 days and then increased. This indicated that N immobilization occurred during the early portion of the incubation period when elm, sea buckthorn and wild peach residue was added to the soil. Soil N levels were low during the entire incubation period when simon poplar, locust, Stipa bungeana, and old world bluestem residue were added to the soil. The addition of plant residue significantly increased SMBC and SMBN in all treatments. The SMBC and SMBN values were greatest in treatments containing plant residue with high total N content and low C/N ratios. The C/N ratios of korshinsk peashrub, sea buckthorn, and wild peach residues were similar, but the amount of N released from these residues and the effects of the residue on SMBC and SMBN in soil were significantly different. This indicates that not only the C/N ratio but also the chemical composition of the plant residue affected decomposition. It is important to consider C and N release characteristics from plant residue in order to adjust the C and N balance of soil when revegetating degraded ecosystems.     

Nitrogen released from different plant residues of the Loess Plateau and their additions on contents of microbial biomass carbon, nitrogen in soil

An incubation method was used to investigate the nitrogen release characteristics from the residue of ten plant species which commonly grow in the northern part of the Loess Plateau. The effect of the residue on soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) was also determined. There were significant differences in the total N content and the C/N ratios among the different types of plant residue. The total N content of the residues ranged from 6.61 to 32.78 g kg^?1. The C/N ratio of the residue ranged from 14 to 65. There was an immediate increase in soil N after alfalfa, erect milkvetch, and korshinsk peashrub residue was added to the soil. In contrast, soil N decreased after elm, sea buckthorn, and wild peach residue was added to the soil. The soil N content remained relatively low for 14–34 days and then increased. This indicated that N immobilization occurred during the early portion of the incubation period when elm, sea buckthorn and wild peach residue was added to the soil. Soil N levels were low during the entire incubation period when simon poplar, locust, Stipa bungeana, and old world bluestem residue were added to the soil. The addition of plant residue significantly increased SMBC and SMBN in all treatments. The SMBC and SMBN values were greatest in treatments containing plant residue with high total N content and low C/N ratios. The C/N ratios of korshinsk peashrub, sea buckthorn, and wild peach residues were similar, but the amount of N released from these residues and the effects of the residue on SMBC and SMBN in soil were significantly different. This indicates that not only the C/N ratio but also the chemical composition of the plant residue affected decomposition. It is important to consider C and N release characteristics from plant residue in order to adjust the C and N balance of soil when revegetating degraded ecosystems.     

黄土区六种植物凋落物与不同形态氮素对土壤微生物量碳氮含量的影响

黄土高原丘陵沟壑区进行的以退耕还林还草为主的生态环境建设,使得进入土壤生态系统有机物的种类及数量发生变化,其对土壤微生物量碳、氮的影响是值得关注的问题。采用室内培养法研究了采自该区6种不同植物凋落物（碳氮比在15.1-50.7之间）及其与不同形态氮素（NH+4-N及NO-3-N）配合对土壤微生物量碳、氮及矿质态氮含量的影响。结果表明,加入不同凋落物均显著提高了土壤微生物量碳、氮含量,其中加入柠条、沙打旺等碳氮比低的凋落物在培养的一段时期内土壤微生物量碳、氮均高于碳氮比高的凋落物（刺槐、沙柳和长芒草）。在加入凋落物再施用NH+4或NO-3,也提高了土壤微生物量碳、氮含量,其中铵态氮处理土壤微生物量碳、氮含量的增加达显著水平,说明微生物更易利用铵态氮。加入C/N高的凋落物后土壤中的矿质氮发生固持,矿质态氮固持量与凋落物的C/N比呈显著的正相关关系。建议在黄土高原丘陵沟壑区植被恢复过程中,有必要考虑不同植物凋落物的碳、氮养分含量及转化特性,以协调土壤碳、氮转化过程。     

黄土高原典型植物根际对土壤微生物生物量碳、氮、磷和基础呼吸的影响

选择黄土高原7种典型植物的根际与非根际土壤为研究对象,对土壤的养分含量、微生物生物量碳、氮、磷和基础呼吸的影响进行了初步研究。结果表明,7种不同植物根际土壤与非根际土壤的养分含量、微生物生物量和基础呼吸均存在显著差异;除冷蒿的土壤微生物生物量磷以外,其他各种植物的根际土壤的养分含量、微生物生物量和基础呼吸均比非根际土壤的高;土壤有机碳、全氮与土壤微生物生物量碳、氮及基础呼吸之间均具有极显著或显著相关关系,表明了土壤微生物生物量碳、氮可以作为判断土壤肥力状况的生物学指标,同时也可为提高土壤肥力水平和土壤培肥效果提供依据。     

黄土高原不同植被带土壤团聚体有机碳和酶活性的粒径分布特征

为探究土壤中各粒级团聚体不同形态有机碳和酶活性的分布特征,以黄土高原延河流域森林带、森林草原带、草原带土壤为对象,研究了不同粒级团聚体总有机碳、易氧化碳和腐殖质碳含量,以及纤维素酶、β-D葡糖苷酶、过氧化物酶、蔗糖酶和脲酶活性,分析了土壤团聚体有机碳及其组分与酶活性之间的相关关系.结果表明： 3种植被带土壤团聚体有机碳及其组分含量表现为森林带＞草原带＞森林草原带,3种形态有机碳含量在0.25～2 mm粒径均最高;不同植被带土壤团聚体有机碳及其组分含量和酶活性在0～10 cm土层大于10～20 cm土层;3种植被带纤维素酶、β-D葡糖苷酶、蔗糖酶和脲酶活性表现为森林带＞草原带＞森林草原带,过氧化物酶活性表现为森林带＞森林草原带＞草原带;3种植被带土壤中各种酶活性随着粒径的减小呈递增趋势.土壤纤维素酶、过氧化物酶、蔗糖酶和脲酶活性与团聚体各种形态碳含量均呈显著正相关.
     

黄土高原不同土壤微生物量碳、氮与氮素矿化势的差异

以采自于黄土高原差异较大的25个农田石灰性耕层土壤为供试土样,对黄土高原主要类型土壤中微生物量碳(Bc)、微生物量氮(BN)和氮素矿化势(NO)的差异性进行了比较研究.结果表明,Bc、BN和NO在不同类型土壤间存在显著差异,由关中平原至陕北风沙区,BC、Bn和NO总体呈现下降趋势,其中以土垫旱耕人为土最高,简育干润均腐土最低,黄土正常新成土和干润砂质新成土居中:土垫旱耕人为土、简育干润均腐土、黄土正常新成土和干润砂质新成土等各土类平均BC分别为305.2μg·g-1,108.4μg·g-1,161.7μg·g-1和125.4μg·g-1,BN分别为43.8μg·g-1,20.3μg·g-1,26.0μg·g-1和30.6μg·g-1,NO分别为223μ·g-1,75μg·g-1,163μg·g-1和193μg·g-1.土壤氮素矿化速率(k)则以简育干润均腐土最大,干润砂质新成土最低,土垫旱耕人为土和黄土正常新成土居中:土垫旱耕人为土、简育干润均腐土、黄土正常新成土和干润砂质新成土的k分别为0.039w-1,0.044w-1,0.031w-1和0.019w-1.不同类型土壤BC、BN与NO的差异,主要与土壤形成过程、输入土壤的植物同化产物和土壤有机质的差异等有关,从较大尺度进一步证明了在黄土高原,土壤有机质是影响BC、BN的主要因子.研究结果对分析黄土高原土壤生产力形成过程具有一定参考价值.     

宁南山区植被恢复对土壤团聚体水稳定及有机碳粒径分布的影响

土壤团聚作用和土壤有机碳固定之间密切相关.对宁南山区不同植被恢复措施和年限下土壤团聚体粒径分布及稳定性、土壤团聚体中有机碳及其组分分布进行了研究,探讨了有机碳及其组分对植被恢复的响应.结果表明,不同植被恢复措施下,土壤团聚体粒径分布表现为“V”字分布:＞5 mm和＜0.25 mm这两个粒径的团聚体含量最多,5-2 mm、1-0.25 mm团聚体的含量次之,2-1 mm粒径的团聚体含量最少.坡耕地的平均重量直径(MWD)最低,为1.4,其他植被恢复措施下土壤的平均重量直径MWD在1.9-3.1之间.不同的植被恢复措施下,0-20 cm土层和20-40 cm土层全土有机碳含量在7.4-17.7 g/kg之间、微生物碳含量分布在50.3-664.7 mg/kg之间、腐殖质碳含量在0.9-2.5g/kg之间.胡敏酸碳含量分布在0.2-0.6 g/kg,富里酸碳含量在0.6-1.9 g/kg之间.全土有机碳、微生物碳、腐殖质碳、富里酸碳均为坡耕地最低,其他植被恢复措施的有机碳、微生物碳、腐殖质碳、富里酸碳含量分别是坡耕地的1.1-2.3倍、2.0-8.4倍、1.0-2.0倍、1.2-2.4倍.不同粒径团聚体有机碳相比较,大多呈现中间高两边低的变化趋势,最大值出现在中间粒径,即5-2 mm、2-1 mm、1-0.25 mm这3个粒径.逐步回归表明,5-2 mm团聚体和1-0.25 mm团聚体有机碳含量的提高有助于土壤水稳性团聚体的形成.研究结果表明,植被恢复提高了土壤团聚体有机碳含量,在碳形态上,富里酸碳和微生物生物量碳对不同植被恢复措施的敏感度较高,胡敏酸碳含量则相对稳定.     

黄土高原土壤团聚体稳定性及抗蚀性能力经度变化特征

分析与探讨了黄土高原地区的土壤理化性质和土壤团聚体稳定性随经度的变化特征,为其植被恢复及利用提供有力的理论支持和依据。采用常规的化学分析方法测定土壤的理化性质,并用干筛与湿筛法结合测定土壤各级团粒含量。结果表明,随着经度的升高,黄土高原地区的土壤有机碳和全氮含量都呈增加趋势,其中定西的含量都是最低的,该地植物以灌木(柠条)为主;全磷含量变化不明显。通过计算土壤团聚体的平均重量直径(MWD值)和土壤可蚀性值(K值),除了定西地区的MWD值最小、K值最大外,其余地区的MWD值、K值分别在2.00、0.19左右,都是随着经度升高波动范围较小。说明黄土高原地区乔木林比灌木林的土壤有机碳和全氮含量高,土壤团聚体稳定性好、抗侵蚀性能强。     

种植模式和施肥对黄土旱塬农田土壤团聚体及其碳分布的影响

本研究以长武黄土高原农业生态试验站33年长期定位试验处理为研究对象,选取撂荒(R)、小麦连作(CK/W)、小麦玉米轮作(L),小麦连作选取单施氮肥(N)、单施磷肥(P)、施氮磷肥(NP)、单施有机肥(M)、氮肥配施有机肥(NM)、磷肥配施有机肥(PM)、氮磷肥配施有机肥(NPM)共10种不同种植模式和施肥田间处理,运用...     

黄土高原北部草地的恢复与重建对土壤有机碳的影响

草地的恢复与重建是黄土高原生态建设的重要内容,探讨草地恢复过程中土壤有机碳密度（SOCD）的变化规律对于合理评价北方水蚀风蚀交错带地区生态恢复的环境效应及其对土壤碳固存潜力的影响具有重要的理论价值。以黄土高原北部水蚀风蚀交错带地区不同生长年限的紫花苜蓿（Medicago sativa）人工草地及其退化后形成的次生草地为主要研究对象,探讨了SOCD的动态变化特征。结果表明,研究区0-100cm土体的SOCD普遍较低,变化范围为1.18-2.81kgCm^-2,略高于地球上荒漠带的水平（1.4kgCm^-2）,显著低于黄土高原中部（4.46-9.95kgCm^-2）与全国（11.52-12.04kgCm^-2）的平均水平。但是当土地利用方式由农田转变为人工草地以后,以及随着人工草地向长芒草（Stipabungeana）次生天然草地的自然演替,SOCD均有不同程度的增加,增加幅度最大可达72%,土壤表现为明显的碳汇。不同土地利用方式0-100cmSOCD的变化顺序为：灌木林地（2.11kgCm^-2）〉次生天然草地（1.95kgCm^-2）〉人工草地（1.91kgCm^-2）〉弃耕地（1.69kgCm^-2）〉农田（1.68kgCm^-2）,但统计差异不显著,意味着植被恢复对土壤碳固存的影响相对较小,该地区土壤固存CO2的潜力并不大,发育较好的次生天然草地0-100cm土体SOCD平均仅为2.20kgCm^-2。对SOCD垂直变化的分析结果表明表层SOC主要固存于表层0-20cm土壤,而且与0-100cm土体的SOCD具有显著的线性相关性,由表层观测值可以有效估计0-100cm土体的SOCD,估计误差为9.9%（0.18kgCm^-2）。     

黄土高原不同干旱类型区苜蓿草地深层土壤干燥化效应

田间实地测了黄土高原不同干旱类型区不同生长年限苜蓿草地0～1000cm土层土壤湿度,分析和比较了各类苜蓿草地深层土壤干燥化效应特征。结果表明,在半湿润区、半干旱区和半干旱偏旱区,各类苜蓿草地土壤湿度平均值分别为10．84％、7．07％和5．45％,明显低于当地土壤稳定湿度值和荒草地土壤湿度值,土壤水分过耗量分别为540．2、641．1mm和455．0mm,平均土壤干燥化速度分别为61．2、101．9mm/a和99．0mm／a;3种类型区各类苜蓿草地年降水入渗深度分别为187．8、144cm和173cm,降水入渗深度以下深层土壤湿度保持稳定的干燥化状态;土壤干燥化强度随苜蓿草地生长年限延长而加剧,3年生苜蓿草地为中度干燥化强度,土壤干层厚度达到500～760cm,4年生以上苜蓿草地已达到严重干燥化和强烈干燥化强度,土壤干层厚度超过940～1000cm;通过粮草轮作使苜蓿草地土壤湿度恢复到当地土壤稳定湿度分别需要6、11a和18a以上。     

黄土高原不同植被带人工刺槐林土壤氮磷转化酶动力学参数及其温度敏感性

土壤酶是有机质降解的催化剂,其动力学特征是表征酶催化性能的重要指标,对评价土壤健康质量有重要作用。本研究选择黄土高原3种植被带下人工刺槐林土壤为对象,探讨了土壤酶动力学参数对温度变化的响应及其温度敏感性(Q₁₀)的变化特征。结果表明: 随着培养温度的升高,土壤丙氨酸转氨酶、亮氨酸氨基肽酶和碱性磷酸酶的潜在最大反应速率(V_max)和半饱和常数(K_m)均呈线性增加,且V_max呈现出森林带>森林草原带>草原带的地带性规律。V_max的温度敏感性(Q10(V_max))为1.14～1.62,K_m的温度敏感性(Q_10(Km))为1.05～1.47,且两者在森林草原带的值均低于其他植被带。在低、高温区,不同土壤酶的Q₁₀在各植被带间的变化也不尽相同。冗余分析显示,Q₁₀与环境变量尤其是土壤养分有显著的相关关系,这表明Q₁₀可能还受到除温度以外其他环境因子的影响。     

Environmental driving factors affecting plant biomass in natural grassland in the Loess Plateau,China

Plant biomass is a key parameter for estimating terrestrial ecosystem carbon (C) stocks, which varies greatly as a result of specific environmental conditions. Here, we tested environmental driving factors affecting plant biomass in natural grassland in the Loess Plateau, China. We found that above-ground biomass (AGB) and below-ground biomass (BGB) had a similar change trend in the order of Stipa bungeana > Leymus secalinus > Artemisia sacrorum > Artemisia scoparia, whereas shoot ratio (R/S) displayed an opposite change trend. There was a significantly positive linear relationship between the AGB and BGB, regardless of plant species (p < 0.05). Furthermore, more than 50% of the AGB were found in 20–50 cm of plant height in Compositae plants (A. sacrorum, A. scoparia), whereas over 60% of the AGB were found in 20–80 cm of plant height in Gramineae plants (S. bungeana, L. secalinus). For each plant species, more than 75% of the BGB was distributed in 0–10 cm soil depth, and 20% was distributed in 10–20 cm soil depth, while less than 5% was distributed in 20–40 cm soil depth. Further, AGB and BGB were highly affected by environmental driving factors (soil properties, plant traits, topographic properties), which were identified by the structural equation model (SEM) and the generalized additive models (GAMs). In addition, AGB was directly affected by plant traits, and BGB was directly affected by soil properties, and soil properties associated with plant traits that affected AGB and BGB through interactive effects were 9.12% and 3.59%, respectively. However, topographic properties had a weak influence on ABG and BGB (as revealed by the lowest total pathway effect). Besides, soil organic carbon (SOC), soil microbial biomass carbon (MBC), and plant height had a higher relative contribution to AGB and BGB. Our results indicate that environmental driving factors affect plant biomass in natural grassland in the Loess Plateau.     

黄土高原草地植物多样性与群落稳定性的关系及其驱动因素

植物多样性对维持生态功能的稳定发挥具有重要作用。以黄土高原不同植被带草地为研究对象,基于野外调查和实验分析,探究黄土高原不同植被带草地植物多样性与群落稳定性特征和二者之间的关系以及影响因素。结果表明：黄土高原草地群落结构特征(地上生物量、地下生物量)与植物多样性具有明显的纬度分布格局,草地植物多样性和生物量均表现出自东南向西北沿森林草原带—森林带—草原带—草原荒漠带逐渐递减趋势。森林草原带草地植物多样性和群落稳定性显著高于森林带、草原带和草原荒漠带;植物多样性与群落稳定性之间存在显著正相关关系,可以作为衡量群落稳定性的指标,其稳定性大小表现为森林草原带>森林带>草原带>草原荒漠带。降雨量是影响植物多样性和群落稳定性的主要因素,并通过改变土壤含水量影响群落稳定性。研究结果揭示了草地植物多样性与群落稳定性之间的关系及驱动机制,为维持黄土高原草地生态系统的群落稳定性提供了科学依据。     

黄土高原草地净初级生产力时空趋势及其驱动因素

草地净初级生产力是生态系统碳循环的关键环节和重要组成部分.本研究使用分段线性回归分析和Pearson相关分析,分析了黄土高原2000-2015年间土地利用类型未改变的草地净初级生产力(NPP)的变化趋势及气候核心因子(年降水量、年强降水量、年有效降水日数、年平均温度、年最高温度、年最低温度)对NPP变化的影响,并借助增...