积雪和丛枝菌根真菌网络对尖喙牻牛儿苗幼苗生长的影响北大核心CSCD

通过野外原位监测及室内分析相结合,剖析了生物因素（土壤真菌菌丝网络）和物理因素（积雪改变）对古尔班通古特沙漠优势短命植物尖喙牻牛儿苗（Erodium oxyrrhynchum）生长的影响。结果表明：减雪与菌丝网络对该植物的生长具有显著复合生态效应。具体表现为：（1）在叶片性状指标方面,PVC旋转造成丛枝菌根真菌菌丝网络被阻断后,尖喙牻牛儿苗各项叶片性状均有所下降。其中以减雪处理组最为明显,生长末期叶面积减少70.92%、叶周长减少37.26%。（2）在植株高度及根系长度方面,菌丝网络被阻断后,尖喙牻牛儿苗株高均有所下降,加雪、减雪处理时下降显著（P〈0.05,分别为40.45%、39.47%）;根长在减雪组下降显著（47.75%）。（3）在植株地上地下生物量分配方面,菌丝网络被阻断后,尖喙牻牛儿苗地上、地下生物量均有所下降,其中减雪处理组下降显著（P〈0.05,分别为80.32%和65.74%）。可见,生物因素和物理因素对植物生长具有双重影响,其中减雪处理与菌丝网络阻隔处理对尖喙牻牛儿苗幼苗生长发育具有显著复合生态效应。为推测荒漠短命植物对冬季降水变化的适应机制及荒漠生态系统的保育提供了科学依据。     

积雪和丛枝菌根真菌网络对尖喙牻牛儿苗幼苗生长的影响

通过野外原位监测及室内分析相结合,剖析了生物因素(土壤真菌菌丝网络)和物理因素(积雪改变)对古尔班通古特沙漠优势短命植物尖喙牻牛儿苗(Erodium oxyrrhynchum)生长的影响。结果表明:减雪与菌丝网络对该植物的生长具有显著复合生态效应。具体表现为:(1)在叶片性状指标方面,PVC旋转造成丛枝菌根真菌菌丝网络被阻断后,尖喙牻牛儿苗各项叶片性状均有所下降。其中以减雪处理组最为明显,生长末期叶面积减少70.92%、叶周长减少37.26%。(2)在植株高度及根系长度方面,菌丝网络被阻断后,尖喙牻牛儿苗株高均有所下降,加雪、减雪处理时下降显著(P0.05,分别为40.45%、39.47%);根长在减雪组下降显著(47.75%)。(3)在植株地上地下生物量分配方面,菌丝网络被阻断后,尖喙牻牛儿苗地上、地下生物量均有所下降,其中减雪处理组下降显著(P0.05,分别为80.32%和65.74%)。可见,生物因素和物理因素对植物生长具有双重影响,其中减雪处理与菌丝网络阻隔处理对尖喙牻牛儿苗幼苗生长发育具有显著复合生态效应。为推测荒漠短命植物对冬季降水变化的适应机制及荒漠生态系统的保育提供了科学依据。     

不同生境/萌发类型尖喙牻牛儿苗生物量分配特征

短命植物是荒漠生态系统重要的植物类群，其具有多样化的生境，且很多种类还具有异时萌发特性。植物生物量积累和分配能体现其对环境的响应与适应性特征，因此，研究不同环境条件下短命植物生物量分配格局有助于进一步了解短命植物的生存策略。以裸沙春萌（Bare Sand-Spring Germination,BS）、藻结皮春萌（Algal-Spring Germination,AS）、地衣结皮春萌（Lichen-Spring Germination,LS）3种自然结皮生境中萌发的尖喙牻牛儿苗春萌株及裸沙区夏季萌发（Summer Germination in Bare Sand,SG）的尖喙牻牛儿苗夏萌株为研究对象，采用全株挖掘法获取地上和地下生物量，系统对比分析了4个类型间植株生物量分配及异速生长关系的差异性，以探究其资源分配策略的变异性和保守型。结果表明：（1）尖喙牻牛儿苗单株地上、地下及总生物量总体表现为BS>AS>LS=SG的格局，其根冠比则呈SG=LS=AS>BS的特征。（2）BS和SG类型植株地上与地下生物量间为等速生长关系，而AS和LS生境为异速生长关系，但4个类型具有共...     

古尔班通古特沙漠短命植物的氮素吸收策略

研究荒漠生态系统同一生活型植物对氮素的利用是否存在生态位分离,有助于深入了解荒漠植物的生存策略,更好掌握氮素对荒漠植物生存的影响。在古尔班通古特沙漠中,广泛分布着4种短命植物尖喙牻牛儿苗(Erodium oxyrrhynchum)、琉苞菊(Hyalea pulchella)、假狼紫草(Nonea caspica)和飘带果(Lactuca undulata),对4种荒漠短命草本植物在不同月份不同土层深度对不同形态氮素的吸收利用进行了研究。结果显示:(1)在不同土层深度,5月4种植物的氮素吸收速率均高于4月的氮素吸收速率;对于不同形态氮素的吸收速率,甘氨酸均低于硝态氮和铵态氮。(2)4月假狼紫草对硝态氮的回收率最高,可达52.3%;5月假狼紫草对铵态氮的回收率最高,可达90.7%。(3)琉苞菊对15N的吸收量低于其他3种植物。(4)4种短命植物不仅可以利用土壤无机氮,还可以有效利用土壤有机氮,且尖喙牻牛儿苗和飘带果对硝态氮有明显的吸收偏好。(5)在古尔班通古特沙漠生态系统中,短命生活型的植物对氮素的吸收能力有着差异和多元化的特点,且均可吸收土壤中的可溶性的有机态氮源。     

生物结皮对荒漠草本植物群落结构的影响

通过人工去除生物结皮试验,分析古尔班通古特沙漠生物结皮对常见荒漠草本植物群落结构的影响。根据人为去除生物结皮的试验结果,结合生物结皮对种子萌发、幼苗存活以及土壤养分和水分等影响,综合分析生物结皮对草本植物多样性的影响。结果表明:尖喙牻牛儿苗(Erodium oxyrrhynchum)、条叶庭荠(Alyssum linifolium)、琉苞菊(Hyalea pulchella)、荒漠庭荠(Alyssum desertorum)及旱麦草(Eremopyrum triticeum)的生物量总和占总生物量的90%以上,是该沙漠的优势草本植物。去除生物结皮后,草本植物的植被高度、物种丰富度和多样性指数都显著提高;但是,植被盖度、密度和群落生物量却显著降低。说明生物结皮的存在改变了古尔班通古特沙漠南缘荒漠草本植物的群落结构,植被盖度和群落生物量提高,这对于防风固沙、稳定沙面具有重要的生态意义。     

类短命植物粗柄独尾草器官生物量分配与估测

粗柄独尾草(Eremurus inderiensis)是古尔班通古特沙漠特有类短命植物。采用全株挖掘法研究粗柄独尾草盛花期的生物学特征、器官生物量分配及生物量估测模型。结果表明：粗柄独尾草地上形态指标之间及其与器官生物量间均呈显著正相关,协同生长关系较强。粗柄独尾草地下生物量平均为(12.00±5.85) g/株,占全株58.23%±6.07%,地上生物量平均为(9.15±5.75) g/株,占全株41.77%±6.07%,根冠比为1.44±0.34。根生物量所占比例最大(51.61%±5.93%),其次为有性繁殖器官(25.14%±5.02%)和光合器官(16.63%±3.75%),这种分配模式体现了类短命植物生活型的特点。根冠比与地上形态指标间均为负相关关系。叶片、花序、地上及地下生物量间的相关生长分析表明,仅叶片重与地上生物量、叶片重与花序生物量间呈等速生长关系,其他均为异速关系。基于D (花柄基径)、HD² (H为株高)的地上、地下和总生物量直接估测模型均较为精确,且地下生物量的直接和间接估测(基于异速关系)效果相同。     

伊犁绢蒿(Seriphidium transiliense)个体功能性状对短期禁牧的可塑性响应

为了探讨禁牧对植物个体功能性状的影响,在新疆呼图壁县、玛纳斯县及昌吉市阿什里乡对短期禁牧下蒿类荒漠草地建群种伊犁绢蒿(Seriphidium transiliense)的个体表型特征、构件生物量及其分配比进行了测定。结果表明:伊犁绢蒿个体功能性状对短期禁牧的响应因禁牧地点的差异而有所不同,呼图壁和玛纳斯样地的大多性状如株高、地上生物量、叶片数、叶生物量均呈显著增加(P 0. 05),而昌吉样地多数功能性状虽为增加,但均不显著。总体分析可知,短期禁牧后伊犁绢蒿的株高、地上生物量、叶片数、茎生物量、叶生物量依次显著增加21. 32%、48. 97%、104. 50%、50. 18%、100. 00%(P 0. 05),根颈直径、一级及三级分枝数出现显著下降,而二级分枝数、生殖生物量、各构件生物量分配比变化不显著。伊犁绢蒿个体表型性状与其构件生物量及分配比间均具有显著的联动效应,且短期禁牧可引起其部分个体功能性状间的相关关系发生显著改变。研究表明,短期禁牧促进伊犁绢蒿个体功能性状的恢复,利于退化蒿类荒漠草地的恢复。     

裸露与沙埋对极端干旱区凋落物分解和养分释放的影响

为了评估沙漠公路防护林林带裸露与沙埋处理下的凋落物分解和养分动态特征,以梭梭（Haloxylon ammodendron）和乔木状沙拐枣（Calligonum arborescens）同化枝、多枝柽柳（Tamarix ramosissima）叶凋落物为研究对象,用凋落物分解袋法进行分解试验。结果表明：（1）3种凋落物的质量损失在2种处理下均存在显著差异,沙埋处理下凋落物质量损失大于裸露处理,至分解试验结束,裸露处理下梭梭、乔木状沙拐枣和多枝柽柳的失重率分别为7%、6.8%、18.1%;沙埋处理下梭梭、乔木状沙拐枣和多枝柽柳的失重率分别为23.7%、9.7%、21.9%;(2)分解过程中,2种处理下凋落物C、N、P含量变化不太一致,梭梭与乔木状沙拐枣同化枝的N与P含量均呈净富集状态,而C含量则呈现净释放状态;多枝柽柳叶的N和P含量分别呈净富集、净释放状态,C含量为富集-释放状态;（3）分解速率k值与相关因素分析表明,凋落物初始N、P、C:N与C:P含量对分解速率影响显著（P<0.01）。这些结果说明,在极端干旱区,沙埋对凋落物的分解过程有显著的积极影响。     

毛乌素沙地天然臭柏、油蒿群落细根分解及影响因子分析

采用埋袋法对毛乌素沙地天然臭柏、油蒿群落的分解速率在2005年4~10月,2006年4~10月间进行了为期2年的动态研究,并同步测定样地的温度、相对湿度、露点温度、绝对湿度、土壤含水率等影响因子。建立了细根重量保持率与时间的数学关系式,揭示了群落内部气象因子的动态变化。结果表明:臭柏和油蒿细根分解系数相差较大(P(0.05),细根分解系数在臭柏群落与臭柏灌丛间差异不显著,臭柏分解系数为油蒿分解系数的44.44%。在对细根分解与其影响因子的相关分析基础上,探讨沙区生态系统中气象因子、土壤水分对细根分解速率的影响,这部分工作的开展对于揭示沙区生态系统的物质循环和能量流动具有重要理论意义。     

匐柄霉对大丽轮枝菌生长及微菌核形成的影响

在离体条件下及棉花植株内测试了匐柄霉对大丽轮枝菌的抑制作用。结果表明,在离体条件下,匐柄霉菌的菌丝体或其培养滤液,对大丽轮枝菌的生长和微菌核形成均有影响。将形态发生变异,不能形成微菌核的大丽轮枝菌菌株转移至ＰＤＡ培养基后,其微菌核形成能力不再恢复。匐柄霉培养滤液的抑菌物质受热不稳定,１００℃处理１０分钟后活性丧失。抑菌物质经硫酸铵、乙醇沉淀初步测定,属非蛋白次生代谢产物。匐柄霉经接种可进入棉株体内,定殖率为７５％～１００％,分布于棉苗根、茎的维管束组织中。与轮枝菌先后或同时混合接种,匐柄霉可减轻棉花黄萎病的症状,以棉苗栽种前用匐柄霉菌分生孢子悬浮液沾根处理效果最明显。     

Litter decomposition and nutrient dynamics of three woody halophytes in the Taklimakan Desert Highway Shelterbelt

Litter decomposition is a crucial biogeochemical process for C and nutrient cycling in nutrient-constrained environments, but the controlling factors on litter decomposition in an extremely arid desert region such as the Taklimakan Desert are relatively unknown. To evaluate the litter decomposition and nutrient dynamic characteristics, five primary litter types of three woody halophytes (Haloxylon ammodendron, Calligonum arborescens, and Tamarix ramosissima) along the Taklimakan Desert Highway Shelterbelt were monitored in litterbags during 420 days, when placed on the soil surface and buried by sand, respectively. The results indicated that the decomposition rate decreased in the order of assimilative branches of H. ammodendron (HA, 0.94), branches of T. ramosissima (TB, 0.55), assimilative branches of C. arborescens (CA, 0.53), seeds of C. arborescens (CS, 0.41), and old branches of H. ammodendron (HB, 0.21) in the surface placement. In contrast, the litters buried by sand displayed a significantly accelerated decomposition rate (F?=?12.28, P?H. ammodendron and branches of T. ramosissima presented P accumulation in both placements, whereas nutrients (N, P, K) and C showed a release pattern during the litter decomposition process, which was influenced by initial litter contents and decomposition rate.     

Dependency of litter decomposition on litter quality,climate change,and grassland type in the alpine grassland of Tianshan Mountains,Northwest China

Litter decomposition is an important component of the nutrient recycling process and is highly sensitive to climate change. However, the impacts of warming and increased precipitation on litter decomposition have not been well studied, especially in the alpine grassland of Tianshan Mountains. We conducted a manipulative warming and increased precipitation experiment combined with different grassland types to examine the impact of litter quality and climate change on the litter decomposition rate based on three dominant species (Astragalus mongholicus, Potentilla anserina, and Festuca ovina) in Tianshan Mountains from 2019 to 2021. The results of this study indicated there were significant differences in litter quality, specific leaf area, and leaf dry matter content. In addition, litter quality exerted significant effects on litter decomposition, and the litter decomposition rate varied in different grassland types. Increased precipitation significantly accelerated the litter decomposition of P. anserina; however, it had no significant effect on the litter decomposition of A. mongholicus and F. ovina. However, warming consistently decreased the litter decomposition rate, with the strongest impact on the litter decomposition of F. ovina. There was a significant interaction between increased precipitation and litter type, but there was no significant interaction between warming and litter type. These results indicated that warming and increased precipitation significantly influenced litter decomposition; however, the strength was dependent on litter quality. In addition, soil water content played a crucial role in regulating litter decomposition in different grassland types. Moreover, we found that the litter decomposition rate exhibited a hump-shaped or linear response to the increase of soil water content. Our study emphasizes that ongoing climate change significantly altered litter decomposition in the alpine grassland, which is of great significance for understanding the nutrient supply and turnover of litter.     

干热河谷罗望子人工林凋落物分解及养分释放

通过长期野外监测和分析,研究了金沙江干热河谷罗望子人工林凋落物分解和养分释放动态,结果表明:经过420d分解期,林地A和林地B的凋落物残留率为42.57%和29.22%,半衰期为0.87a和0.75a,周转期为4.81a和3.61a;养分迁移方式,K元素是淋溶-富集-释放;N、Ca、Mg、Cu元素是富集-释放,Fe元素是富集,P元素在林地A和林地B中迁移方式略有差异;养分释放特征,P、Ca、Mg元素表现为净释放,七种元素释放率大小,林地A和林地B均为:Ca﹥K﹥P﹥Mg﹥N﹥Cu﹥Fe;P、K、Ca、Mg元素易分解和循环,返回林地时间较短,易被林木吸收。罗望子林凋落物的分解总体特征符合亚热带气候的地带性特点,受气温和降雨量影响较小。     

天山北坡4种栽培杨树的功能性状分析

植物功能性状可以用来推断植物生活史策略,反映生态系统功能。为了研究天山北坡4种栽培杨树适应环境的生态策略差异,对其主要功能性状进行比较分析。结果表明,4种杨树的叶片大小、叶片厚度、叶干物质含量、茎皮厚度、木材密度和根、茎、叶全N,P,K含量均差异显著;但4种杨树间比叶面积差异不显著;新疆杨单叶面积和干物质量最大,胡杨叶片厚度和木材密度最大,钻天杨茎皮厚度最大;4种杨树的叶片N含量均显著高于茎和根,茎和根的N和P含量差异均不显著,除胡杨外,其他3种杨树叶片P含量均显著高于茎和根,K含量在4种杨树的根、茎、叶器官中表现不一致;钻天杨根、茎、叶的N,P,K养分含量都相对较高,俄罗斯杨的根、茎、叶的N,P,K养分含量都相对较低。4种杨树功能性状不同反映了植物对环境的适应性差异。     

Effects of ultraviolet(UV) radiation and litter layer thickness on litter decomposition of two tree species in a semi-arid site of Northeast China

Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet(UV) radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. Here, we conducted a field-based experiment in 2011 in the southeastern Horqin Sandy Land, Northeast China, to investigate the effects of UV radiation, litter layer thickness, and their interaction on the mass loss and chemical properties of decomposing litter from Xiaozhuan poplar(Populus × xiaozhuanica) and Mongolian pine(Pinus sylvestris var. mongolica) plantation trees. We found that UV radiation accelerated the decomposition rates of both the Xiaozhuan poplar litter and Mongolian pine litter. For both species, the thick-layered litter had a lower mass loss than the thin-layered litter. The interaction between UV radiation and litter layer thickness significantly affected the litter mass loss of both tree species. However, the effects of UV radiation on the chemical properties of decomposing litter differed between the two species, which may be attributed to the contrasting initial leaf litter chemical properties and morphology. UV radiation mostly had positive effects on the lignin concentration and lignin/N ratio of Xiaozhuan poplar litter, while it had negative effects on the N concentration of Mongolian pine litter. Moreover, litter layer thickness and its interaction with UV radiation showed mostly positive effects on the N concentration and lignin/N ratio of Xiaozhuan poplar litter and the ratios of C/N and lignin/N of Mongolian pine litter, and mostly negative effects on the C/N ratio of Xiaozhuan poplar litter and the N concentration of Mongolian pine litter. Together, these results reveal the important roles played by UV radiation and litter layer thickness in the process of litter decomposition in this semi-arid region, and highlight how changes in the litter layer thickness can exert strong influences on the photodegradation of litter in tree plantations.     

The return and loss of litter phosphorus in different types of sand dunes in Horqin Sandy Land, northeastern China

Litter phosphorus(P) return is important to maintain the P cycle and balance in the sandy land of arid areas.In this study,we determined the loss and return of litter P in sand dune areas and elucidated their relationship.We investigated litter production and litter P amount,and simulated leaf litter moving dynamics to understand the relationships between the loss of litter P and the total litter P,and between the return of litter P and the total litter P in active(AD),semi-stabilized(SSD) and stabilized(SD) dunes in Inner Mongolia,northeastern China.The vegetation litter P was 12.6,94.5,and 201.6 mg P/m2 in AD,SSD,and SD,respectively.A significant movement and loss of leaf litter P with time occurred on the three types of sand dunes.As a result,the loss of P was 7.4,46.9,and 69.8 mg P/m2 and the return of P was 5.5,47.6,and 131.8 mg P/m2 in AD,SSD,and SD,respectively.The relationship between both loss and return of P and total litter P in AD,SSD,and SD was revealed by linear regression.The slope of the regression line indicated the rate of loss or return of litter P.From AD to SD,the loss rate showed a declining slope(0.52,0.32,and 0.17 for AD,SSD,and SD,respectively),and the return rate showed a rising slope(0.48,0.67,and 0.83 for AD,SSD,and SD,respectively).The loss of litter P should be regarded in the local management of vegetation and land in sand dune areas.Improved vegetation restoration measures are necessary to decrease litter P loss to maintain the stability of ecosystems in sand dune areas.     

荒漠草原棕钙土地带凋落物分解速率与分解过程的研究

1985—1987年作者在内蒙古荒漠草原对两种主要植物短花针茅和蓖齿蒿的凋落物进行了分解速率与分解过程的研究,结果表明: 1.这两种植物材料的分解,大抵可分为三个阶段。1)快速失重阶段;一般一年左右时间,约有40%凋落物被分解;2)缓慢失重阶段:一般2—4年左右时间,约有40—80%凋落物被分解;3)极缓慢失重阶段:一般4→10年时间,约有80%凋落物被分解。2.在分解过程中,各种营养物质的分解表现出不同的特点。在第一阶段,脂肪分解最快,从原来的100%很快被分解,只剩下20%,其次是灰分、蛋白质可分解50%,而无氮浸出物可保留初始状态的70%左右,纤维素分解甚慢,仅分解掉20%左右。总之,在第一阶段分解过程中,各种营养物质的分解表现出脂肪>灰分、蛋白质>无氮浸出物>纤维素。3.荒漠草原区凋落物的分解较温带森林区要低。在温带森林95%的凋落物被分解约需4年,而在荒漠草原。约需8—16年。     

青海半干旱农区对气候变暖后适应状况的探讨

本文从掌握的青海半干旱农业区－“河湟”谷地部分气象资料出发,建立地区蒸发量与年平均气温间的回归方程,探讨全球变化后这些地区干燥指数状况可能发生的改变。现今４０年来,该区域干暖与湿冷相配合;气温趋暖化并非显著,但干燥指数有所上升,区域向湿润发展。当设定未来平均气温升高２℃,降水量增加１０％时,青海半干旱农业区,在未来气候情景下蒸发量的增加比降水的增加来得快,将导致干旱胁迫加重。但降水量增加２０％时,     

塔里木沙漠公路防护林凋落物的持水特性

采用野外典型抽样和室内浸水的方法,对4种定植年限不同的塔里木沙漠公路防护林带内凋落物的储量、持水量和吸水速率进行研究。结果表明：① 不同定植年限防护林内凋落物储量依次为：13 a林带 (42.3 t•hm^-2) >6 a林带 (39.6 t•hm^-2) > 10 a林带 (39.1 t•hm^-2) > 7 a林带 (16.2 t•hm^-2)。② 沙漠公路防护林的林下未分解层凋落物持水量的排序为：梭梭 >柽柳>沙拐枣;而半分解层凋落物持水量的排序是：柽柳>梭梭>沙拐枣,且防护林内凋落物最大持水量半分解层均大于未分解层。③ 各林龄不同树种不同分解程度的凋落物持水量与浸水时间之间呈对数关系,最佳拟合关系式为W=b+a lg t,吸水速率与浸水时间之间呈幂函数关系,关系式为：V=ktⁿ,凋落物吸水速率在0～1 h内急剧下降,4 h以后下降平稳,其吸水作用逐渐减小。