Changes in the relationship between species richness and belowground biomass among grassland types and along environmental gradients in Xinjiang,Northwest China

The association between biodiversity and belowground biomass (BGB) remains a central debate in ecology. In this study, we compared the variations in species richness (SR) and BGB as well as their interaction in the top (0-20 cm), middle (20-50 cm) and deep (50-100 cm) soil depths among 8 grassland types (lowland meadow, temperate desert, temperate desert steppe, temperate steppe desert, temperate steppe, temperate meadow steppe, mountain meadow and alpine steppe) and along environmental gradients (elevation, energy condition (annual mean temperature (AMT) and potential evapotranspiration (PET)), and mean annual precipitation (MAP)) based on a 2011-2013 survey of 379 sites in Xinjiang, Northwest China. The SR and BGB varied among the grassland types. The alpine steppe had a medium level of SR but the highest BGB in the top soil depth, whereas the lowland meadow had the lowest SR but the highest BGB in the middle and deep soil depths. The SR and BGB in the different soil depths were tightly associated with elevation, MAP and energy condition; however, the particular forms of trends in SR and BGB depended on environmental factors and soil depths. The relationship between SR and BGB was unimodal in the top soil depth, but SR was positively related with BGB in the middle soil depth. Although elevation, MAP, energy condition and SR had significant effects on BGB, the variations in BGB in the top soil depth were mostly determined by elevation, and those in the middle and deep soil depths were mainly affected by energy condition. These findings highlight the importance of environmental factors in the regulations of SR and BGB as well as their interaction in the grasslands in Xinjiang.     

Effects of warming and clipping on plant and soil properties of an alpine meadow in the Qinghai-Tibetan Plateau,China

Climate warming and livestock grazing are known to have great influences on alpine ecosystems like those of the Qinghai-Tibetan Plateau(QTP) in China. However, it is lacking of studies on the effects of warming and grazing on plant and soil properties in these alpine ecosystems. In this study, we reported the related research from manipulative experiment in 2010–2012 in the QTP. The aim of this study was to investigate the individual and combined effects of warming and clipping on plant and soil properties in the alpine meadow ecosystem. Infrared radiators were used to simulate climate warming starting in July 2010, while clipping was performed once in October 2011 to simulate the local livestock grazing. The experiment was designed as a randomized block consisting of five replications and four treatments: control(CK), warming(W), clipping(C) and warming+clipping combination(WC). The plant and soil properties were investigated in the growing season of the alpine meadow in 2012. The results showed that W and WC treatments significantly decreased relative humidity at 20-cm height above ground as well as significantly increases air temperature at the same height, surface temperature, and soil temperature at the depth of 0–30 cm. However, the C treatment did not significantly decrease soil moisture and soil temperature at the depth of 0–60 cm. Relative to CK, vegetation height and species number increased significantly in W and WC treatment, respectively, while vegetation aboveground biomass decreased significantly in C treatment in the early growing season. However, vegetation cover, species diversity, belowground biomass and soil properties at the depth of 0–30 cm did not differ significantly in W, C and WC treatments. Soil moisture increased at the depth of 40–100 cm in W and WC treatments, while belowground biomass, soil activated carbon, organic carbon and total nitrogen increased in the 30–50 cm soil layer in W, C and WC treatments. Although the initial responses of plant and soil properties to experimental warming and clipping were slow and weak, the drought induced by the downward shift of soil moisture in the upper soil layers may induce plant belowground biomass to transfer to the deeper soil layers. This movement would modify the distributions of soil activated carbon, organic carbon and total nitrogen. However, long-term data collection is needed to further explain this interesting phenomenon.     

Degradation leads to dramatic decrease in topsoil but not subsoil root biomass in an alpine meadow on the Tibetan Plateau,China

Understanding the effects of degradation on belowground biomass (BGB) is essential for assessment of carbon budget of the alpine meadow ecosystem on the Tibetan Plateau, China. This ecosystem has been undergoing serious degradation owing to climate change and anthropogenic activities. This study examined the response of the vertical distribution of plant BGB to degradation and explored the underlying mechanisms in an alpine meadow on the Tibetan Plateau. A field survey was conducted in an alpine meadow with seven sequential degrees of degradation in the Zoige Plateau on the Tibetan Plateau during the peak growing season of 2018. We measured aboveground biomass (AGB), BGB, soil water content (SWC), soil bulk density (SBD), soil compaction (SCOM), soil organic carbon (SOC), soil total nitrogen (STN), soil total phosphorus (STP), soil available nitrogen (SAN), and soil available phosphorus (STP) in the 0-30 cm soil layers. Our results show that degradation dramatically decreased the BGB in the 0-10 cm soil layer (BGB_0-10) but slightly increased the subsoil BGB. The main reason may be that the physical-chemical properties of surface soil were more sensitive to degradation than those of subsoil, as indicated by the remarked positive associations of the trade-off value of BGB_0-10 with SWC, SCOM, SOC, STN, SAN, and STP, as well as the negative correlation between the trade-off value of BGB_0-10 and SBD in the soil layer of 0-10 cm. In addition, an increase in the proportion of forbs with increasing degradation degree directly affected the BGB vertical distribution. The findings suggest that the decrease in the trade-off value of BGB_0-10 in response to degradation might be an adaptive strategy for the degradation-induced drought and infertile soil conditions. This study can provide theoretical support for assessing the effects of degradation on the carbon budget and sustainable development in the alpine meadow ecosystem on the Tibetan Plateau as well as other similar ecosystems in the world.     

Ecological biomass allocation strategies in plant species with different life forms in a cold desert,China

Biomass allocation patterns among plant species are related to their adaptive ecological strategies. Ephemeral, ephemeroid and annual plant life forms represent three typical growth strategies of plants that grow in autumn and early spring in the cold deserts of China. These plants play an important role in reducing wind velocity in the desert areas. However, despite numerous studies, the strategies of biomass allocation among plant species with these three life forms remain contentious. In this study, we conducted a preliminary quadrat study during 2014-2016 in the southern part of the Gurbantunggut Desert, China, to investigate the allocation patterns of above-ground biomass (AGB) and below-ground biomass (BGB) at the individual level in 17 ephemeral, 3 ephemeroid and 4 annual plant species. Since ephemeral plants can germinate in autumn, we also compared biomass allocation patterns between plants that germinated in autumn 2015 and spring 2016 for 4 common ephemeral species. The healthy mature individual plants of each species were sampled and the AGB, BGB, total biomass (TB), leaf mass ratio (LMR) and root/shoot ratio (R/S) were calculated for 201 sample quadrats in the study area. We also studied the relationships between AGB and BGB of plants with the three different life forms (ephemeral, ephemeroid and annual). The mean AGB values of ephemeral, ephemeroid and annual plants were 0.806, 3.759 and 1.546 g/plant, respectively, and the mean BGB values were 0.106, 4.996 and 0.166 g/plant, respectively. The mean R/S value was significantly higher in ephemeroid plants (1.675) than in ephemeral (0.154) and annual (0.147) plants. The mean LMR was the highest in annual plants, followed by ephemeroid plants and ephemeral plants, reflecting the fact that annual plants allocate more biomass to leaves, associated with their longer life span. Biomass of ephemeral plants that germinated in autumn was significantly higher than those of corresponding plants that germinated in spring in terms of AGB, BGB and TB. However, the R/S value was similar in plants that germinated in autumn and spring. The slope of regression relationship between AGB and BGB differed significantly among the three plant life forms. These results support different biomass allocation hypotheses. Specifically, at the individual level, the AGB and BGB partitioning supports the allometric hypothesis for ephemeroid and annual plants and the isometric hypothesis for ephemeral plants.     

短期增温下青藏高原多年冻土区植物生长季土壤水分的动态变化

以青藏高原腹地典型高寒草甸植被类型为研究对象,采用红外灯加热的方法模拟全球增温,并利用水分探头,于2012年植物生长季（5—9月）获取0~100 cm不同土层深度土壤水分含量数据,并分析其对增温的响应。结果表明：① 短期增温对高寒草甸土壤水分含量有提高作用,但增幅并不显著（P>0.05）,平均提高2.85%。② 土壤水分含量随土层深度的增加呈现先减少后增加的趋势,在10~20 cm土层深度处降为最低值13.8%,在60~100 cm土层深度附近达到了20.57%的最高值;对照组5个月10~20 cm土层深度的土壤水分含量显著低于其他土层,而增温组0~20 cm土层深度的土壤含水量显著低于其他土层深度,表明增温对表层（0~10 cm）的土壤含水量影响较大,对深层土壤含水量的影响则较小,而且短期增温不会对土壤水分的垂直分布趋势产生影响。③ 土壤水分含量随时间的变化,在5—8月呈上升趋势,表明在青藏高原北麓河地区植物生长季,8月是其土壤水分含量最充足的月份,到了9月土壤中含水量开始降低,但5个土层深度降幅均不明显;增温组土壤水分含量随时间的变化趋势与对照组基本一致。     

Effects of long-term warming on the aboveground biomass and species diversity in an alpine meadow on the Qinghai-Tibetan Plateau of China

Ecosystems in high-altitude regions are more sensitive and respond more rapidly than other ecosystems to global climate warming.The Qinghai-Tibet Plateau(QTP)of China is an ecologically fragile zone that is sensitive to global climate warming.It is of great importance to study the changes in aboveground biomass and species diversity of alpine meadows on the QTP under predicted future climate warming.In this study,we selected an alpine meadow on the QTP as the study object and used infrared radiators as the warming device for a simulation experiment over eight years(2011-2018).We then analyzed the dynamic changes in aboveground biomass and species diversity of the alpine meadow at different time scales,including an early stage of warming(2011-2013)and a late stage of warming(2016-2018),in order to explore the response of alpine meadows to short-term(three years)and long-term warming(eight years).The results showed that the short-term warming increased air temperature by 0.31℃and decreased relative humidity by 2.54%,resulting in the air being warmer and drier.The long-term warming increased air temperature and relative humidity by 0.19℃and 1.47%,respectively,and the air tended to be warmer and wetter.The short-term warming increased soil temperature by 2.44℃and decreased soil moisture by 12.47%,whereas the long-term warming increased soil temperature by 1.76℃and decreased soil moisture by 9.90%.This caused the shallow soil layer to become warmer and drier under both short-term and long-term warming.Furthermore,the degree of soil drought was alleviated with increased warming duration.Under the long-term warming,the importance value and aboveground biomass of plants in different families changed.The importance values of grasses and sedges decreased by 47.56%and 3.67%,respectively,while the importance value of weeds increased by 1.37%.Aboveground biomass of grasses decreased by 36.55%,while those of sedges and weeds increased by 8.09%and 15.24%,respectively.The increase in temperature had a non-significant effect on species diversity.The species diversity indices increased at the early stage of warming and decreased at the late stage of warming,but none of them reached significant levels(P>0.05).Species diversity had no significant correlation with soil temperature and soil moisture under both short-term and long-term warming.Soil temperature and aboveground biomass were positively correlated in the control plots(P=0.014),but negatively correlated under the long-term warming(P=0.013).Therefore,eight years of warming aggravated drought in the shallow soil layer,which is beneficial for the growth of weeds but not for the growth of grasses.Warming changed the structure of alpine meadow communities and had a certain impact on the community species diversity.Our studies have great significance for the protection and effective utilization of alpine vegetation,as well as for the prevention of grassland degradation or desertification in high-altitude regions.     

Effects of soil nutrients and climate factors on belowground biomass in an alpine meadow in the source region of the Yangtze-Yellow rivers,Tibetan Plateau of China

Improving our knowledge of the effects of environmental factors(e.g.soil conditions,precipitation and temperature) on belowground biomass in an alpine grassland is essential for understanding the consequences of carbon storage in this biome.The object of this study is to investigate the relative importance of soil nutrients and climate factors on belowground biomass in an alpine meadow in the source region of the Yangtze and Yellow rivers,Tibetan Plateau.Soil organic carbon(SOC),total nitrogen(TN) and total phosphorous(TP) contents and belowground biomass were measured at 22 sampling sites across an alpine meadow on the Tibetan Plateau.We analyzed the data by using the redundancy analysis to determine the main environmental factors affecting the belowground biomass and the contribution of each factor.The results showed that SOC,TN and TP were the main factors that influenced belowground biomass,and the contribution of SOC,TN and TP on biomass was in the range of 47.87%–72.06% at soil depths of 0–30 cm.Moreover,the combined contribution of annual mean temperature(AMT) and mean annual precipitation(MAP) on belowground biomass ranged from 0.92% to 4.10%.A potential mechanism for the differences in belowground biomass was caused by the variations in soil nitrogen and phosphorous,which were coupled with SOC.A significant correlation was observed between MAP and soil nutrients(SOC,TN and TP) at the soil depth of 0–10 cm(P0.05).We concluded that precipitation is an important driving force in regulating ecosystem functioning as reflected in variations of soil nutrients(SOC,TN and TP) and dynamics of belowground biomass in alpine grassland ecosystems.     

巴音布鲁克主要草地类型表层土壤有机碳特征及其影响因素的研究

以新疆天山中段巴音布鲁克主要草地类型为研究对象,分析了不同草地类型土壤有机碳(SOC)的分布特征及其与气候因子、植被特征和土壤特性的关系。结果表明:分布在盆地海拔最低处的高山沼泽化草甸的土壤有机碳含量最高,而分布在盆地中间海拔的高山草原最低,分布在较高海拔的高寒草甸和高山草原化草甸处于高山沼泽化草甸和高山草原之间。0-30cm土壤有机碳含量与空气相对湿度、草地生产力、植被盖度、土壤含水量呈显著正相关(P<0.05),与土壤容重、土壤紧实度、土壤pH呈显著负相关(P<0.05),土壤有机碳与温度存在一定负相关,但未达到显著水平。偏相关分析显示,影响表层土壤有机碳含量最主要的因素是土壤含水量、土壤紧实度、草地生产力、空气相对湿度。     

高寒草地主要类型土壤因子特征及对地上生物量的影响

以新疆巴音布鲁克高寒草地五种主要草地类型的实测数据为依据,探讨了土壤因子随环境变化的特点及其对地上生物量之间的影响。结果表明:沼泽高寒草甸土壤含水量最大,有机质和速效N、P、K的含量都最高。高寒草原土壤含水量最小,有机质和速效养分的含量最低。土壤含水量与速N存在显著正相关,速P与速N和速K之间分别存在显著正相关,速K和有机质存在显著正相关。土壤含水量和速N含量是影响地上生物量的主要土壤因子,回归方程分别为Y=379.954X+28.238(F=12.562,P<0.05)和Y=0.864X-122.874(F=21.352,P<0.05)。     

Effects of rainfall patterns on annual plants in Horqin Sandy Land,Inner Mongolia of China

Growth of annual plants in arid environments depends largely on rainfall pulses. An increased understanding of the effects of different rainfall patterns on plant growth is critical to predicting the potential responses of plants to the changes in rainfall regimes, such as rainfall intensity and duration, and length of dry intervals. In this study, we investigated the effects of different rainfall patterns(e.g. small rainfall event with high frequency and large rainfall event with low frequency) on biomass, growth characteristics and vertical distribution of root biomass of annual plants in Horqin Sandy Land, Inner Mongolia of China during the growing season(from May to August) of 2014. Our results showed that the rainfall patterns, independent of total rainfall amount, exerted strong effects on biomass, characteristics of plant growth and vertical distribution of root biomass. Under a constant amount of total rainfall, the aboveground biomass(AGB), belowground biomass(BGB), plant cover, plant height, and plant individual and species number increased with an increase in rainfall intensity. Changes in rainfall patterns also altered the percentage contribution of species biomass to the total AGB, and the percentage of BGB at different soil layers to the total BGB. Consequently, our results indicated that increased rainfall intensity in future may increase biomass significantly, and also affect the growth characteristics of annual plants.     

高寒草甸不同类型草地土壤机械组成及肥力比较

研究了青藏高原高寒草甸不同类型草地土壤机械组成和土壤养分变化特征,并用相关分析探讨了土壤理化特征、土壤机械组成对不同草地类型群落物种组成、生物量变化的响应。结果表明:不同草地类型土壤机械组成分布大致是矮嵩草草甸:粉粒>细砂粒>粘粒>粗砂粒;高山嵩草草甸:细砂粒>粉粒>粘粒>粗砂粒;藏嵩草沼泽化草甸:细砂粒>粉粒>粘粒>粗砂粒;金露梅灌丛:粉粒>粘粒≥细砂粒>粗砂粒。矮嵩草草甸、高山嵩草草甸为粉砂质粘壤土,藏嵩草沼泽化草甸为壤土,金露梅灌丛为壤质粘土。矮嵩草草甸、高山嵩草草甸和金露梅灌丛土壤颗粒分布相对比较均匀(除藏嵩草沼泽化草甸外),主要集中在<0.5mm的范围内,土壤粘粒含量普遍大于20%。土壤全量养分和速效养分以及土壤物理特征均影响着高寒草甸不同草地类型土壤质量和土壤结构。土壤结构和养分状况是判断高寒草甸生态系统生态功能维持的关键指标之一。     

围栏与不同放牧强度对东祁连山高寒草甸植被和土壤的影响

在东祁连山高寒草地,对围栏7年和不同放牧强度的草地进行了物种数、地上生物量、地下生物量、土壤理化性质等研究。结果表明,围栏7年的高寒草地鲜草产量为425.8 g·m-2,显著高于夏季中牧159.3 g·m-2和夏季重牧91.0 g·m-2,但与冬季轻牧、夏季轻牧差异不显著。围栏条件下的物种数为26.3种·16 m-2,显著低于其他放牧条件下的物种数,但显著高于夏季重牧条件下的物种数23.0种·16 m-2;轻度或重度放牧都会使物种数减少,夏季中牧下的物种数最高(33.5种·16 m-2)。在0~10 cm的表层土壤中,围栏7年的草地根系生物量显著高于其他放牧强度。随着放牧强度的增加,根系生物量在0~10 cm土壤中呈下降趋势,在30~40 cm土壤中则表现为升高趋势。围栏7年的土壤容重低于其他放牧强度下的土壤容重,但差异不显著;夏季重牧的土壤容重显著高于围栏7年和其他放牧强度的土壤容重。随着放牧强度的增加,0~10 cm土壤碱解氮增加,围栏7年草地最低。围栏封育可有效改善和恢复草地植被,但不能长时间禁牧不进行放牧利用。合理的放牧能够维护高寒草甸草地生态系统功能、促进物种丰富度和土壤营养的均衡。     

高寒草甸退化对土壤电导率变化影响的研究

土壤电导率是表征土壤水溶性盐的一个重要指标,可反映土壤盐渍化程度.为了研究高寒草甸退化对土壤电导率的影响,以三江源区未退化高寒草甸和退化高寒草甸为研究对象,系统分析了退化高寒草甸的植被特征和土壤特征与土壤电导率的相互关系.结果表明:高寒草甸退化会对土壤电导率产生显著负影响,且土壤电导率与评价高寒草甸的退化指标植被盖度、...     

Analysis of growth and resource allocation

At UCPE we are exploring high-level, ecologically based models of growth and resource allocation in herbaceous plants, including weed species. In them, allocation is driven by variables from Plant Strategy Theory, such as below-and above-ground‘environmental stress'. A‘hyperbolic’model is described in which the allocation of resources into above-and below-ground plant parts is jointly controlled by (i) the absolute amounts of below-and above-ground stress that the plant‘perceives'; (ii) the ratio of below-ground to above-ground stress; and (iii) by the maximum growth potential of the plant itself. The inputs to the model are the fraction of its maximum potential that the plant attains and its root-shoot allometric growth coefficient. The outputs from the model are indices of the above-and below-ground stresses‘perceived’by the plant. The latter arc otherwise particularly difficult to estimate when growth and allocation are being controlled simultaneously by several suboptimal environmental variables, as happens in many crop weed systems.     

Above- and below-ground biomass and carbon stocks of different tree plantations in central Iran

In arid and semi-arid lands using industrial wastewater for irrigating tree plantations offers a great opportunity to fulfill the purpose of Clean Development Mechanism by sequestering carbon in living tissues as well as in soil. Selection of tree for plantation has a great effect on the goal achievements, especially when the managers deal with afforestation projects rather than reforestation projects. The objective of this study was to quantify the above- and below-ground biomass accumulation and carbon storages of the 17-year-old monoculture plantations of mulberry(Morus alba L.), black locust(Robinia pseudoacacia L.), Eldar pine(Pinus eldarica Medw.) and Arizona cypress(Cupressus arizonica Greene) planted in central Iran. To assess the potential carbon storage, we destructively measured individual above- and below-ground tree biomass and developed and scaled models at stand level. Furthermore, carbon content at three soil depths(0–15, 15–30, 30–45 cm), the litter and the understory were assessed in sample plots. The results showed that the total amount of carbon stored by Eldar pine(36.8 Mg/hm2) was higher than those stored by the trees in the other three plantations, which were 23.7, 10.0, and 9.6 Mg/hm2 for Arizona cypress, mulberry and black locust plantations, respectively. For all the species, the above-ground biomass accumulations were higher than those of the below-ground. The root mass fractions of the deciduous were larger than those of the coniferous. Accordingly, the results indicate that the potential carbon storages of the coniferous were higher than those of the deciduous in arid regions.     

Effects of freezing intensity on soil solution nitrogen and microbial biomass nitrogen in an alpine grassland ecosystem on the Tibetan Plateau,China

The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem;however,the research on the impact of the freeze-thaw action on nitrogen processes of the alpine grassland ecosystem on the Tibetan Plateau has not yet attracted much attention.In this study,the impact of the freezing strength on the soil nitrogen components of alpine grassland on the Tibetan Plateau was studied through laboratory freeze-thaw simulation experiments.The 0–10 cm topsoil was collected from the alpine marsh meadow and alpine meadow in the permafrost region of Beilu River.In the experiment,the soil samples were cultivated at –10°C,–7°C,–5°C,–3°C and –1°C,respectively for three days and then thawed at 2°C for one day.The results showed that after the freeze-thaw process,the soil microbial biomass nitrogen significantly decreased while the dissolved organic nitrogen and inorganic nitrogen significantly increased.When the freezing temperature was below –7°C,there was no significant difference between the content of nitrogen components,which implied a change of each nitrogen component might have a response threshold toward the freezing temperature.As the freeze-thaw process can lead to the risk of nitrogen loss in the alpine grassland ecosystem,more attention should be paid to the response of the soil nitrogen cycle of alpine grasslands on the Tibetan Plateau to the freeze-thaw process.     

天山南坡高寒草地物种多样性及地上生物量研究

在新疆天山巴音布鲁克草原对高寒草甸、高寒草原和高寒草甸化草原的物种多样性进行了研究,结果表明:盖度+高度指标测度群落物种多样性指数要优于盖度和株数指标,更适于测度高寒草地的物种多样性指数。丰富度指数、Margalef指数与Shannon-wiener指数相关性显著,在小的空间研究尺度内,草地植物群落物种多样性指数受丰富度指数的影响较大。地上生物量与丰富度指数、Margalef指数和Shannon-wiener指数呈负相关关系。     

不同放牧压力下荒漠草原土壤有机碳特征及其与植被之间关系的研究

研究了荒漠草原土壤有机碳的特征及其与植被之间的关系。结果表明:0-10cm和10-20cm土层土壤有机碳含量随着放牧强度的增加而降低,未放牧区(CK)>轻度放牧区(LG)>中度放牧区(MG)>重度放牧区(HG),中度放牧区和重度放牧区分别显著低于未放牧区(P<0.05);0-10cm土层土壤有机碳含量与草地地上生物量和植被盖度具有极强的相关性,与草群高度具有较强的相关性;10-20cm土层土壤有机碳与草地地上生物量和植被盖度具有极强的相关性,而与草群高度的相关性较弱;根据相关性的强弱,建立了土壤有机碳与草地地上生物量和植被盖度的线性回归模型。     

高寒矮嵩草草甸覆被动态变化对土壤气候的影响分析

文中从季节动态变化出发,探讨了覆被对土壤温、湿度的影响特点。表明:有植被覆盖区,在4月下旬到8月下旬期间的随季节进程中,土壤温度与无植被区相比是逐渐升高的,其温度升高的倾向率达0.2276℃/旬。随植被盖度的加大土壤湿度降低,0-60cm整层土壤湿度以1.2587%/旬的速率递减。植被能滞留大部分太阳辐射,发生植被的蒸散要消耗大量的土壤水分。     

Impact of sand burial on maize(Zea mays L.)productivity and soil quality in Horqin sandy cropland,Inner Mongolia,China

Croplands are often suffering from sand burial in dry regions of northern China.For studying this phenomenon,we carried out a case study of field experiment including four sand burial levels,i.e.shallow(1–3 cm),moderate(8–12 cm)and deep(15–20 cm)sand burials,and no sand burial(control,CK),in a typical agro-pastoral transitional zone in Naiman Banner of eastern Inner Mongolia.The aim of this study was to assess the impacts of sand burial on maize(Zea mays L.)productivity and the soil quality along a gradient of burial depths.Results showed that there was a strong negative effect of sand burial on maize productivity and soil quality,which significantly declined(P0.05)under moderate and deep sand burial treatments.In comparison with the CK,the maize yield and above-ground biomass reduced by 47.41% and 39.47%,respectively.The soil silt and clay,soil water,soil organic carbon and total nitrogen contents under deep sand burial decreased by 67.85%,40.32%,86.52% and 82.11%,respectively,while microbial biomass carbon,microbial abundance and enzyme activity decreased by 89.78%,42.28%–79.66% and 69.51%–97.71%,respectively.There was no significant effect on crop productivity and soil quality with shallow sand burial treatment.The correlations analysis showed that there was significant positive correlations of both maize yield and above-ground biomass with soil silt and clay,soil organic carbon and total nitrogen contents,p H,electrical conductivity,soil water content,microbial abundance and biomass and all tested soil enzyme activities.Stepwise regression analysis indicated that soil water and total nitrogen contents,urease,cellobiohydrolase and peroxidase activities were key determining factors for maize productivity.This combination of factors explains reason of the decreased maize productivity with deep sand burial.We found that degradation of cropland as a result of sand burial changed soil physical-chemical properties and soil enzyme activities in the plow layer,and decreased overall maize productivity.Furthermore,decreased soil enzyme activity was a better indicator to predict sandy cropland degradation.