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。     

Damage by wind-blown sand and its control measures along the Taklimakan Desert Highway in China

Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the'Dead Sea'due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.     

典型荒漠植物凋落物分解及养分动态研究

采用分解网袋法,对古尔班通古特沙漠南缘粗柄独尾草(Eremurus inderiensis)、尖喙牻牛儿苗(Erodium oxyrrhynchum)和沙漠绢蒿(Seriphidium santolinum)3种荒漠植物叶、茎和根的分解、养分释放特性进行了研究。结果表明：叶片、茎、根系的质量损失过程均符合指数衰减模型。经过364 d的分解,粗柄独尾草叶、粗柄独尾草根、尖喙牻牛儿苗叶、尖喙牻牛儿苗茎、尖喙牻牛儿苗根、沙漠绢蒿茎、沙漠绢蒿根的失重率分别为41.96%、81.94%、42.18%、29.32%、47.02%、20.66%和20.71%;3种植物根、茎、叶的分解速率存在显著差异,分解速率依次为：粗柄独尾草根>叶;尖喙牻牛儿苗根>叶>茎;沙漠绢蒿根>茎。在整个分解过程中,N和P含量总的趋势表现为释放,叶、根凋落物质量损失与初始N、P含量显著负相关,非生物因素对其分解有重要影响。     

模拟氮沉降对天山云杉凋落叶分解及其养分释放的影响

采用野外模拟试验,通过设计4种氮处理〔CK(对照,不施氮)、LN(低氮,5 kg·hm~(-2)·a~(-1))、MN(中氮,10kg·hm~(-2)·a~(-1))、HN(高氮,15 kg·hm~(-2)·a~(-1))〕,研究了氮沉降对天山云杉凋落叶分解及养分释放的影响。结果表明:1分解24个月后CK凋落叶干重残留率分别是LN、MN和HN的1.04倍、1.16倍和1.23倍,且4种处理间差异显著(P0.05)。CK条件下凋落叶分解50%为4.58 a,分别比LN、MN和HN多0.46 a、0.75 a和1.35 a;相应地分解95%需要的时间分别多2.01 a、3.24 a和5.87 a,说明施氮对天山云杉凋落叶的分解起到了促进作用,且促进作用随着氮沉降量的增加而加大。2从凋落叶月分解速率看,表现为HNMNLNCK,且随着分解时间的延长,4种处理间的差异逐渐缩小。3氮沉降促进了天山云杉凋落叶中木质素和纤维素的分解,同时促进了C元素的释放,增加了N元素的累积,降低了C/N值。     

乌兰布和沙漠东北缘防护林内外沙尘暴低空结构特征

基于内蒙古磴口荒漠生态系统国家定位观测研究站近地层(050m)风沙监测塔所收集的8次沙尘暴的沙尘水平通量、垂直通量和风速风向数据,对乌兰布和沙漠东北缘中小尺度条件下的防护林内外沙尘暴过程中风况变化、沙尘分布特征以及防护林对沙尘暴的影响进行研究。结果表明:①沙尘暴发生过程中,防护林内外风速均随高度增加呈现递增趋势,风速廓线特征遵循幂函数,防护林内外均以W、WNW、NE方向为主,但每个方向所占比例不同。②防护林外沙尘水平通量及沙尘浓度随高度增高显著减小,其垂直分布特征均符合指数函数关系;防护林内沙尘水平通量及沙尘浓度则随着高度增高缓慢上升,其垂直分布特征均符合幂函数关系。沙尘垂直通量则均随着高度的增高明显减小,其垂直分布特征均符合幂函数关系。③沙尘暴经过防护林体系时,风速显著削弱,平均消减31.03%;沙尘水平通量降低298.16g·m^-2,垂直通量降低0.37g·m^-2,沙尘浓度降低22.48g·m^-2。     

放牧绵羊排泄物在荒漠草原土壤内的养分降解

试验研究了放牧绵羊粪便在内蒙古短花针茅草原土壤内的降解。结果显示:羊粪干物质的降解率为0.74mg.g-1.day-1,有机物质、C和N含量在一年的试验期间分别降解了25.0%、35.5%和16.6%;各成分间的降解有显著的相关性,其降解符合回归曲线方程为y=y0+a(1-e-bx);夏季是羊粪分解的主要时期。     

Litter decomposition and C and N dynamics as affected by N additions in a semi-arid temperate steppe,Inner Mongolia of China

Litter decomposition is the fundamental process in nutrient cycling and soil carbon（C） sequestration in terrestrial ecosystems. The global-wide increase in nitrogen（N） inputs is expected to alter litter decomposition and,ultimately, affect ecosystem C storage and nutrient status. Temperate grassland ecosystems in China are usually N-deficient and particularly sensitive to the changes in exogenous N additions. In this paper, we conducted a 1,200-day in situ experiment in a typical semi-arid temperate steppe in Inner Mongolia to investigate the litter decomposition as well as the dynamics of litter C and N concentrations under three N addition levels（low N with 50 kg N/（hm2？a）（LN）, medium N with 100 kg N/（hm2？a）（MN）, and high N with 200 kg N/（hm2？a）（HN）） and three N addition forms（ammonium-N-based with 100 kg N/（hm2？a） as ammonium sulfate（AS）, nitrate-N-based with 100 kg N/（hm2？a） as sodium nitrate（SN）, and mixed-N-based with 100 kg N/（hm2？a） as calcium ammonium nitrate（CAN）） compared to control with no N addition（CK）. The results indicated that the litter mass remaining in all N treatments exhibited a similar decomposition pattern： fast decomposition within the initial 120 days, followed by a relatively slow decomposition in the remaining observation period（120–1,200 days）. The decomposition pattern in each treatment was fitted well in two split-phase models, namely, a single exponential decay model in phase I（〈398 days） and a linear decay function in phase II（≥398 days）. The three N addition levels exerted insignificant effects on litter decomposition in the early stages（〈398 days, phase I; P〉0.05）. However, MN and HN treatments inhibited litter mass loss after 398 and 746 days, respectively（P〈0.05）. AS and SN treatments exerted similar effects on litter mass remaining during the entire decomposition period（P〉0.05）. The effects of these two N addition forms differed greatly from those of CAN aft     

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。     

不同施氮量对半干旱区还田玉米秸秆腐解及养分释放特征的影响

为了揭示还田玉米秸秆在不同施氮水平下的腐解及养分释放特征,在马铃薯田间定位试验中,设置了6个不同施氮水平(T1:0 kg·hm^-2;T2:75 kg·hm^-2;T3:150 kg·hm^-2;T4:225 kg·hm^-2;T5:300 kg·hm^-2; T6:375 kg·hm^-2),研究其对还田玉米秸秆腐解及养分释放特征的影响。研究表明:还田玉米秸秆的腐解主要发生在前90 d,在此期间玉米秸秆腐解较快,T1～T6处理的玉米秸秆腐解率分别为37.3%、40.3%、44.8%、45.0%、50.8%、48.4%,以T5处理为最高,处理间差异显著(P<0.05);同时,T1～T6处理的玉米秸秆碳、氮释放率分别为48.2%～56.6%、33.8%～44.4%,T5处理下秸秆的碳、氮释放率均显著高于其他处理(P<0.05),而秸秆磷、钾的释放率分别为43.1%～49.2%、90.5%～93.0%,处理间无显著性差异。还田150 d后,玉米秸秆的腐解率为5...     

塔中一号公路防沙体系不同地貌部位风沙危害差异研究

塔中一号沙漠公路是塔里木盆地石油物资运输的主要干线之一 ,它深入沙漠腹地 ,走向与风向夹角很大 ,因此沙害严重且频繁。通过对公路防沙体系实地调查测量 ,得出以下结论 :垄间平沙地沙害较轻 ,以风沙流滞留积沙为主 ,固沙带平均全埋宽度 9.0 9m;沙垄迎风坡较严重 ,平均全埋宽度 0 .94m、压埋 1 .96m、风蚀 0 .43m;垄顶最严重 ,平均全埋宽度 1 5 .5 9m、压埋 6.68m、风蚀 3.1 5 m;沙垄背风坡较轻 ,平均全埋宽度 2 .85 m,压埋 0 .0 4 m。     

Effects of parasitic plant Cistanche deserticola on chlorophyll a fluorescence and nutrient accumulation of host plant Haloxylon ammodendron in the Taklimakan Desert

The parasitic plant Cistanche deserticola attaches to Haloxylon ammodendron, a perennial shrub with high tolerance to salinity and drought. However, little was known about the parasite-host relation between the two species. Effects of the parasite on chlorophyll a fluorescence and nutrient accumulation in the host plant (H. ammodendron) were investigated in the Taklimakan Desert. Some photosynthetic parameters of both host and non-host H. ammodendron plants were measured by in vivo chlorophyll a fluorescence technology in the field. The assimilating branches of host and non-host plants were collected and nutrient and inorganic ion contents were analyzed. The results from field experiments showed that the infection of C. deserticola reduced the non-photochemical quenching of the variable chlorophyll fluorescence (NPQ) and the potential maximum quantum yield for primary photochemistry (F v /F m ) of the host. Compared with non-host plants, the host H. ammodendron had low nutrient, low inorganic ion contents (Na + and K + ) and low K + /Na + ratios in the assimilating branches. It suggested that C. deserticola infection reduced the nutrient acquisition and caused damage to the photoprotection through thermal dissipation of the energy of the photosystem II in the host, resulting in a decrease in the tolerance to salinity and high radiation. It was concluded that the attachment of the parasite plant (C. deserticola) had negative effects on the growth of its host.     

塔克拉玛干沙漠北缘荒漠过渡带风沙流结构特征分析

利用多种集沙仪,通过野外实时输沙观测,对塔克拉玛干沙漠北缘荒漠过渡带的地表风沙流特征进行了分析,结果表明：① 100 cm高度范围内,总输沙量的47.3%分布在30 cm高度内,这一比例小于前人的研究结果;输沙量随高度的变化比较符合幂函数分布。② 风沙流输沙的粒径以细砂、极细砂与粉砂为主,各高度层所占比例均达99%以上;风沙流输沙平均粒径随高度增加而减小,沙尘的含量随高度增加呈现“象鼻”状分布。③ 风沙流中贴地层风速廓线受风沙相互作用的影响,不再符合对数分布,更加符合幂函数u=az^b分布。     

塔克拉玛干沙漠腹地建立农业生态体系的初步研究

塔克拉玛干沙漠腹地生态条件恶劣 ,建立农业生态体系需采取特别的措施。两年试验表明 ,供试 71种作物大部分适应性较差 ,蔬菜产量相对较低 ;能量的产投比低 ,养分的利用率低。因此 ,在塔克拉玛干沙漠腹地建立农业生态体系时 ,应采取科学的田间管理措施 ,充分利用地力     

沙漠公路防护林乔木状沙拐枣的平茬效益分析

在极端生境胁迫下,乔木状沙拐枣种植7-8年后即出现长势减弱,自然枯死等现象,本文对7a生乔木状沙拐枣植株进行了人工平茬试验,并对其平茬效益做了分析,得出以下结论:(1)乔木状沙拐枣的再生能力较强,第一次平茬后新生枝株高,冠幅,地径等迅速增长,且经过第二次平茬后仍能保持良好的生长状态,生物效益显著。(2)平茬后乔木状沙拐枣生长旺盛,特别是同化枝表面积增长最快,第一次平茬植株生长2年后其同化枝面积大小已接近未平茬植株。(3)在沙漠公路防护林现有的管理模式和灌溉制度下,对老化衰退的乔木状沙拐枣植株进行平茬后,取得了良好的效果。平茬促进了乔木状沙拐枣的生长发育,从复壮更新的角度来看,有利于乔木状沙拐枣的再生和防护林生态利用率的提高。     

Diurnal dynamics of soil respiration and the influencing factors for three land-cover types in the hinterland of the Taklimakan Desert,China

Knowledge of soil respiration and the influencing factors in desert ecosystems is essential to understanding carbon dynamics and responses of biotic and abiotic processes in soils to climate change. In this study, soil respiration rate(R_s) for three land-cover types(shifting sandy land, sandy land with straw checkerboard barriers, and shelter forest land) in the hinterland of the Taklimakan Desert was measured in May 2015 using an automated soil CO_2 flux system. The effects of soil temperature(T_s) and soil water content(W_s) on R_s were also analyzed. The results showed that R_s values in shifting sandy land, sandy land with straw checkerboard barriers, and shelter forest land were all low and exhibited obvious diurnal fluctuations. The establishment of straw checkerboard barriers in sandy land had no significant effect on R_s, while the establishment of shelterbelts significantly increased R_s. Shifting sandy land and sandy land with straw checkerboard barriers were carbon sinks at night and early morning and were carbon sources in the daytime, while shelter forest land always acted as a carbon source during the whole day. The synergistic effect of T_s and W_s could better explain the diurnal dynamics in R_s than single factor. In shifting sandy land and sandy land with straw checkerboard barriers, W_s was identified as a limiting factor influencing the diurnal dynamics of R_s. Furthermore, a relatively strong hysteresis loop existed between R_s and T_s. In contrast, in shelter forest land, R_s was significantly influenced by T_s, and a relatively weaker hysteresis loop existed between R_s and W_s.     

Blown sand motion within the sand-control system in the southern section of the Taklimakan Desert Highway

Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the northern region in terms of aeolian sand geomorphology and formation environment. Based on the field observation data of airflow and aeolian sand transport, continuous monitoring data of erosional and depositional processes between 14 April 2009 and 9 April 2011 and data of surface sand grains from the classical section along the southern edge of the Taklimakan Desert Highway, this paper reported the blown sand motion within the sand-control system of the highway. The main results are as follows: 1) The existing sand-control system is highly effective in preventing and controlling desertification. Wind velocities within the sand-control system were approximately 33%–100% of those for the same height above the mobile sand surface. Aeolian sand fluxes were approximately 0–31.21% of those of the mobile sand surface. Sand grains inside the system, with a mean diameter of 2.89 φ, were finer than those(2.15 φ) outside the system. In addition, wind velocities basically followed a logarithmic law, but the airflow along the classical section was mainly determined by topography and vegetation. 2) There were obvious erosional and depositional phenomena above the surface within the sand-control system, and these phenomena have very consistent patterns for all observation points in the two observed years. The total thicknesses of erosion and deposition ranged from 0.30 to 14.60 cm, with a mean value of 3.67 cm. In contrast, the deposition thicknesses were 1.90–22.10 cm, with a mean value of 7.59 cm, and the erosion thicknesses were 3.51–15.10 cm, with a mean value of 8.75 cm. The results will aid our understanding of blown sand within the sand-control system and provide a strong foundation for optimizing the sand-control system.     

青海高原地区绿肥毛叶苕子腐解规律及养分释放特征

为了解绿肥毛叶苕子（Vicia Villosa L.）在青海高原地区对土壤的培肥效果以及为农作物提供养分情况,在田间利用尼龙网袋法,研究毛叶苕子腐解特性和氮磷钾等养分释放规律。结果表明:绿肥毛叶苕子在翻压后50 d内腐解速度较快,腐解率达38%,后期腐解速度缓慢,在取样结束后,累积腐解率为86.39%;整个腐解过程中氮磷钾养分释放速率表现为氮>钾>磷,氮和钾的养分释放趋势存在一致性,在52 d内快速释放,养分释放率分别为56.54%、74.27%,后期释放速率缓慢,在腐解结束时,其养分累积腐解率达91.31%、99.04%;磷的释放速率缓慢,且波动性较大,在腐解周期内磷素含量呈上升趋势,取样结束后,累积腐解率为75.71%。绿肥毛叶苕子的干物质累积腐解率、养分累积释放率与腐解时间的关系可以通过线性函数和对数函数拟合。预测本试验处理可为后茬作物地块提供氮素172.80 kg·hm^-2、磷素10.93 kg·hm^-2、钾素139.63 kg·hm^-2。     

Contrasting effects of nitrogen addition on litter decomposition in forests and grasslands in China

Nitrogen (N) addition has profound impacts on litter-mediated nutrient cycling. Numerous studies have reported different effects of N addition on litter decomposition, exhibiting positive, negative, or neutral effects. Previous meta-analysis of litter decomposition under N addition was mainly based on a small number of samples to allow comparisons among ecosystem types. This study presents the results of a meta-analysis incorporating data from 53 published studies (including 617 observations) across forests, grasslands, wetlands, and croplands in China, to investigate how environmental and experimental factors impact the effects of N addition on litter decomposition. Averaged across all of the studies, N addition significantly slows litter decomposition by 7.02%. Considering ecosystem types, N addition significantly accelerates litter decomposition by 3.70% and 11.22% in grasslands and wetlands, respectively, clearly inhibits litter decomposition by 14.53% in forests, and has no significant effects on litter decomposition in croplands. Regarding the accelerated litter decomposition rate in grasslands due to N addition, litter decomposition rate increases slightly with increasing rates of N addition. However, N addition slows litter decomposition in forests, but litter decomposition is at a significantly increasing rate with increasing amounts of N addition. The responses of litter decomposition to N addition are also influenced by the forms of N addition, experiential duration of N addition, humidity index, litter quality, and soil pH. In summary, N addition alters litter decomposition rate, but the direction and magnitude of the response are affected by the forms of N addition, the rate of N addition, ambient N deposition, experimental duration, and climate factors. Our study highlights the contrasting effects of N addition on litter decomposition in forests and grasslands. This finding could be used in biogeochemical models to better evaluate ecosystem carbon cycling under increasing N deposition due to the differential responses of litter decomposition to N addition rates and ecosystem types.     

防护林下草本植物层片物种多样性与环境因子的关系

沿塔里木沙漠公路防护林白北向南设置了10个调查样地,对草本植物的多度、盖度、丰富度进行调查,记录和测定各样地内地下水的埋深、电导率、矿化度,土壤电导率、灌木平均冠幅、灌木层郁闭度等环境因子.分析各样地物种多样性、样地间相似性的差异,以及草本植物层片物种多样性与环境因子的关系.结果表明:塔里木沙漠公路防护林下草本植物层片...