人工小叶锦鸡儿(Caragana microphylla)灌丛土壤水分动态研究

采用由植被空间序列推断时间系列的方法 ,分析了 1984、1987、1995和 1999年建立的人工小叶锦鸡儿固沙植被土壤水分的时空变化特征 .结果表明 ,受沙地土壤机械组成的影响 ,沙地土壤组成以物理性沙粒为主 ,>0 .0 1mm沙粒占 97%以上 ,凋萎湿度为 1.5 5 % ,田间持水量为 5 .5 % ,土壤最大有效水为3.95 % .随着固沙植被优势度的增加 ,小叶锦鸡儿灌丛下土壤含水量持续下降 ,1984年建立的植被区土壤含水量明显低于 1999年建立的植被区 ;在年内土壤水分季节变化中 ,4个阶段植被区土壤水分状况在 4～6月不断降低 ,到 6月达到最低值 ,7～ 10月逐渐回升 ;对于建立较早的植被区 (1984和 1987年 ) ,土壤水分垂直变化表现出随着土层深度的增加 ,土壤含水量逐层递减的趋势 ,特别是 70cm下土层中 ,土壤含水下降明显 ,含水量低于凋萎湿度 ;由于对根际区域土壤水分的利用 ,加剧了固沙植被区深层土壤 (70cm下 )水分的亏缺 ,进而影响植被物种的组成 ,随着小叶锦鸡儿灌丛年龄的增加 ,浅根性植物所占比重增加 .

Interspecific Transition Among Caragana microphylla, C. davazamcii and C. korshinskii Along Geographic Gradient. Ⅰ. Ecological and RAPD Evidence

The former plant population survey has shown that three genetically-related species, Caraganamicrophylla Lam., C. davazamcii Sancz. and C. korshinskii Kom., form a geographical replacement series inNei Mongol Plateau. The present study on population distribution, taxonomy, morphology, development andgenetic structure demonstrated that the geographical distribution of these three species was successiveand in gradual change, thus forming a geographical cline which extended from the east to the west of NeiMongol Plateau. With an analysis of climate change over time, it was considered that the formation of thisgeographical cline was a result of plant adaptation to its natural environment.

Interspecific Transition Among Caragana microphylla, C. davazamcii and C. korshinskii Along Geographic Gradient. Ⅱ. Characteristics of Photosynthesis and Water Metabolism

The characteristics of photosynthesis and water metabolism of Caragana microphylla Lam.,C. davazamcii Sancz. and C. korshinskii Kom. populations in different sites (117.6o-105.7o E, 44.6o-38.8o N)were studied. (1) From the east to the west, the responses of the three species to photosyntheticallyavailable radiation (PAR) in net photosynthesis rate increased, the relative humidity of the air whichcorresponded to the occurrence of maximum photosynthesis rate decreased, and the corresponding airtemperature increased. Along the same gradient, the before-noon superiority of the photosynthesis be-came evident, and the photosynthesis rate and the light use efficiency (LUE ) increased, while the transp-iration rate decreased, thus the water use efficiency (WUE ) increased notably, and the leaf water contentdecreased gradually. From the east to the west, the plants took a water-saving strategy step by step withhigher photosynthesis rate and lower transpiration rate. These physiological changes in the plants wereadaptable to the conditions of light, temperature and humidity in the habitat of the plants, and might be thebiological foundation for the geographical transition among C. microphylla , C. davazamcii and C. korshinskii.(2) The adaptation of photosynthetic system of C. microphylla , C. davazamcii and C. korshinskii to PAR, airhumidity and temperature exhibited the interspecific continuity, which was consistent with theenvironmental gradient. In different species and different sites, the diurnal changes of net photosynthesisrate, the daily cumulative value of net photosynthesis, the diurnal changes of transpiration rate, the dailycumulative value of transpiration, the water use efficiency and the diurnal changes of leaf water contentvaried with longitudinal descent (from the east to the west). The characteristics of photosynthesis andwater metabolism indicated that the geographical transition among C. microphylla , C. davazamcii and C.korshinskii was in gradual change, and these three species formed a geographical cline.

内蒙古高原小叶锦鸡儿(Caragana microphylla)中间锦鸡儿(C．davazamcii)和柠条锦鸡儿(C．korshinskii)的遗传多样性及遗传关系

采用RAPD技术对10个具较大地理跨度的小叶锦鸡儿、中间锦鸡儿和柠条锦鸡儿种群的遗传多样性和遗传关系进行了研究。共检测到678个位点,多态条带比率(PPB)为100%;特有位点41个,占6.05%。总体上3种锦鸡儿的遗传多样性表现出自东向西递减的趋势,分析表明其与生长地点年均气温呈显著负相关。AMOVA表明:3种锦鸡儿种间变异只占总体变异的6.08%,且显著性检验表明这种变异不显著;种内种群间的变异占总变异的11.90%;总变异的主要部分来自种群内部(82.02%)。3种锦鸡儿各种群总体分析结果表明:种群内变异比率Hpop/Hsp为0.8013,基因分化系数Gst为0.1603,种群每代迁移数Nm为2.6192,显示种群间存在一定强度的基因流,3种锦鸡儿间表现为异交性。3种锦鸡儿多样性高低及种群聚类分布格局都表现出一定的地理连续性。

Soil exchangeable base cations along a chronosequence of Caragana microphylla plantation in a semi-arid sandy land,China

As a pioneer leguminous shrub species for vegetation re-establishment, Caragana microphylla is widely distributed in the semi-fixed and fixed sandy lands of the Horqin region, North China. C. microphylla planta- tions modify organic carbon （SOC）, nitrogen （N） and phosphorus dynamics, bulk density and water-holding capacity and biological activities in soils, but little is known with regard to soil exchange properties. Variation in soil ex- changeable base cations was examined under C. microphylla plantations with an age sequence of 0, 5, 10, and 22 years in the Horqin Sandy Land, and at the depth of 0-10, 10-20, and 20-30 cm, respectively. C. microphylla has been planted on the non-vegetated sand dunes with similar physical-chemical soil properties. The results showed that exchangeable calcium （Ca）, magnesium （Mg）, and potassium （K）, and cation exchange capacity （CEC） were significantly increased, and Ca saturation tended to decrease, while Mg and K saturations were increased with the plantation years. No difference was observed for exchangeable sodium （Na） neither with plantation years nor at soil depths. Of all the base cations and soil layers, exchangeable K at the depth of 0-10 cm accumulated most quickly, and it increased by 1.76, 3.16, and 4.25 times, respectively after C. microphylla was planted for 5, 10, and 22 years. Exchangeable Ca, Mg, and K, and CEC were significantly （P〈0.001） and positively correlated with SOC, total N, pH and electrical conductivity （EC）. Soil pH and SOC are regarded as the main factors influencing the variation in ex- changeable cations, and the preferential absorption of cations by plants and different leaching rates of base cations that modify cation saturations under C. microphylla plantation. It is concluded that as a nitrogen-fixation species, C. microphylla plantation is beneficial to increasing exchangeable base cations and CEC in soils, and therefore can improve soil fertility and create favorable microenvironments for plants and creatures in the semi-arid sandy land ecosystems.

Variation in soil water content to rainfall under Caragana microphylla shrub in Horqin Sandy Land

In order to investigate the spatio-temporal variability of soil water content to rainfall under Caragana microphylla shrub in Horqin Sandy Land,a plot of 25 m × 25 m,where there were 6 shrub canopies of C. microphylla,was sited for measuring soil water content at two soil layers of 0-20 cm (top layer) and 20-40 cm (lower layer). Soil water content was measured on the 1st,5th,10th and 15th day after a 42 mm rainfall in Naiman of Inner Mongolia. The results showed that soil water contents at both layers under C. microphylla shrub were gradually decreased after the rain. Soil water content at the top layer outside the shrub canopy was higher than that inside the shrub canopy within 5 days,and became similar inside and outside the shrub canopy on the 10th day after the 42 mm rainfall,and it was lower outside than that inside the shrub canopy on the 15th day. The soil water content at lower layer in the area without shrubs was higher than that under shrub canopy all along. All the measured values of soil water content can be fitted to a variogram model. There was significant autocorrelation of the values of soil water content between top layer and lower layer,except for the fourth measured values of soil water content at top layer. The range and spatial dependence of soil water content at top layer were lower than that at lower layer.

A Leguminous Shrub (Caragana microphylla) in Semiarid Sandy Soils of North China

Caragana microphylla Lam., a pioneer leguminous shrub species for vegetation re-establishment, is widely distributed in the semi-fixed and fixed sandy lands of the Horqin region. Some soil chemical and physical properties were measured under the canopy of C. microphylla and in the adjacent open areas to determine the effects of individual shrubs on soil properties. The influence of isolated C. microphylla on chemical and physical properties of the topsoil was significantly different between plots under the shrub canopy and in the shrub interspaces. Beneath the shrub canopy greater amounts of fine particle fractions, a higher water-holding capacity, and a lower bulk density, as well as higher aboveground and belowground litter biomass were found. Soil organic C and total N concentrations were 23%-31.6% and 14%-27.2% higher under the shrub canopies than in the shrub interspaces, respectively, giving rise to 'islands of fertility'. In a desertified sandy grassland ecosystem, C. microphylla was believed to play a major role in organic C sequestration, N accumulation, and the hydrologic cycle. Additionally, it has been found to be of ecological importance for vegetative restoration and reversal of desertification.

The response of Caragana microphylla seedlings to water table changes in Horqin Sandy Land,China

This paper focuses on the growth response of Caragana microphylla seedlings to changes of artificially controlled water table in Horqin Sandy Land, China. Monitoring results of soil water content shows that soil moisture is closely correlated to groundwater depths. Soil volumetric water increased rapidly when close to water sources and finally stabilized in a saturated state. The soil moisture trend of CK （control） increased gradually at 0-50 cm of soil depth then decreased to 4% below 50 cm soil depth. C. microphylla can adapt to different soil environments by changes in ecological and physiological characteristics. By comparing the ecological characteristics of C. microphylla seedlings at various water tables, we found that a shallow water table of 40 cm depth inhibited seedling groundwater depth of 120 em was more advantageous for plant growth because of weak ecological characteristics. A height and canopy growth of C. microphylla seedlings. During the first two years, the most suitable water depth for root biomass was 120 cm, and 180 cm for root length. The growth of vertical roots is positively correlated with groundwater depth, and root thickness is the determinate factor for root biomass while the fine root is the determinate factor for root length. A thick root would grow much more in a natural drought environment while access to ground water promotes the growth of fine roots.

Stable isotopes reveal varying water sources of Caragana microphylla in a desert-oasis ecotone near the Badain Jaran Desert

Understanding the variation in a plant’s water sources is critical to understanding hydrological processes in water-limited environments. Here, we measured the stable-isotope ratios(δ18 O) of xylem water of Caragana microphylla, precipitation,soil water from different depths, and groundwater to quantitatively analyze the proportion of water sources for the shrub.We found that the water sources of C. microphylla differed with the plant’s ages and the seasons. The main water source for young shrubs was upper-soil water, and it showed significant changes with seasonal precipitation inputs. In summer,the proportion contributed by shallow water was significantly increased with increased precipitation inputs. Then, the contribution from shallow-soil water decreased with the decline in precipitation input in spring and autumn. However, the adult shrubs resorted to deep-soil layers and groundwater as the main water sources during the whole growing season and showed much less seasonal variation. We conclude that the main water source of the young shrubs was upper-soil water and was controlled by precipitation inputs. However, once the shrub gradually grew up and the roots reached sufficient depth, the main water sources change from the upper-soil layer recharged by precipitation to deep-soil water and groundwater, which were relatively stable and abundant in the desert ecosystem. These results also suggest that desert shrubs may be able to switch their main water sources to deep and reliable water sources as their age increases, and this adjustment to water availability carries significant importance for their acclimation to the desert habitat.

Effects of Caragana microphylla plantations on organic carbon sequestration in total and labile soil organic carbon fractions in the Horqin Sandy Land, northern China

Afforestation is conducive to soil carbon（C） sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon（SOC） fractions in semi-arid sandy lands. In the present study, we examined the effects of Caragana microphylla Lam. plantations with different ages（12-and 25-year-old） on sequestrations of total SOC as well as labile SOC fractions such as light fraction organic carbon（LFOC） and microbial biomass carbon（MBC）. The analyzed samples were taken from soil depths of 0–5 and 5–15 cm under two shrub-related scenarios： under shrubs and between shrubs with moving sand dunes as control sites in the Horqin Sandy Land of northern China. The results showed that the concentrations and storages of total SOC at soil depths of 0–5 and 5–15 cm were higher in 12-and 25-year-old C. microphylla plantations than in moving sand dunes（i.e., control sites）, with the highest value observed under shrubs in 25-year-old C. microphylla plantations. Furthermore, the concentrations and storages of LFOC and MBC showed similar patterns with those of total SOC at the same soil depth. The 12-year-old C. microphylla plantations had higher percentages of LFOC concentration to SOC concentration and MBC concentration to SOC concentration than the 25-year-old C. microphylla plantations and moving sand dunes at both soil depths. A significant positive correlation existed among SOC, LFOC, and MBC, implying that restoring the total and labile SOC fractions is possible by afforestation with C. microphylla shrubs in the Horqin Sandy Land. At soil depth of 0–15 cm, the accumulation rate of total SOC under shrubs was higher in young C. microphylla plantations（18.53 g C/（m^2·a）; 0–12 years） than in old C. microphylla plantations（16.24 g C/（m^2·a）; 12–25 years）, and the accumulation rates of LFOC and MBC under shrubs and between shrubs were also higher in young C. microphylla plantations than in old C. microphylla plantations. It can be concluded that the establishment of C. microphylla in the Horqin Sandy Land may be a good mitigation strategy for SOC sequestration in the surface soils.

ISSR analysis of Caragana microphylla(Leguminosae) in different temperature gradients

Caragana microphylla is the most dominant and constructive shrub species in the Horqin Sandy Land of northeastern China. We evaluated the level of genetic variation within and among C. microphylla populations sampled from three different temperature gradients in the Horqin Sandy Land by using inter-simple sequence repeat polymorphism （ISSR） molecular markers. The results show that eight ISSR primers generated 127 bands, of which 123 （96.85%） were polymorphic. At the species level, genetic diversity was relatively high （P = 96.85%, h = 0.3143, I = 0.4790）. The highest genetic diversity was observed in the Subp6 population from low temperature regions, whereas the lowest diversity was found in the Subp2 population from high temperature regions. Six populations of C. microphylla clustered into two clades. These results have important implications for restoring and managing the degraded ecosystem in arid and semi-arid areas.

Microclimate Effect of Artificial Caragana microphylla Communities in Horqin Sandy Land

Caragana microphylla is one of the key species for vegetation restoration in Horqin Sandy Land. Adopting field investigation and outdoor experiments,the microclimate effect of artificial C. microphylla communities with different restoration years were studied by observing wind velocity,air temperature,relative humidity and soil temperature. The results show that:( 1) Caragana microphylla community has an obvious wind-breaking effect near ground surface. Compared with shifting dunes,the wind velocity in the 6-year-old and 11-year-old C. microphylla shrubs at the height of 30 cm separately decreases by 71. 9% and 76. 0%.( 2) Mean daily temperature in the 6-year-old and 11-yearold C. microphylla communities is 3. 7 ℃ and 4. 9 ℃ lower than in shifting dunes,respectively.( 3) The relative humidity of air in the Caragana microphylla shrubs is higher than in shifting dunes.( 4) Soil temperature in C. microphylla plantation is lower than in shifting dunes. These results are significant in further exploring material and energy exchange near surface layer of artificial vegetation in the extremely arid condition.

采煤沉陷区模拟土壤侵蚀胁迫对灌木生理生长特性的影响

【目的】探究半干旱地区采煤活动造成的土壤侵蚀对北沙柳Salix cheilophila、小叶锦鸡儿Caragana microphylla生长生理特性的影响,阐明植物在逆境胁迫下的适应性及生存策略。【方法】在野外原位试验条件下,对北沙柳、小叶锦鸡儿根部进行原位根系断裂试验来模拟土壤侵蚀胁迫,设置对照组(CK)和轻度胁迫(S1)、中度胁迫(S2)和重度胁迫(S3)四种不同程度的土壤侵蚀,测定了不同胁迫处理下两种灌木的生长指标和生理指标变化,并使用模糊数学隶属函数综合评价其抗逆性。【结果】土壤侵蚀胁迫显著抑制北沙柳和小叶锦鸡儿的株高、冠幅、枝条长度和枝条直径,且随着侵蚀胁迫程度增大,抑制程度越明显;北沙柳叶片叶绿素含量随着土壤侵蚀胁迫程度增大而降低,且随胁迫时间延长呈逐渐降低趋势,而小叶锦鸡儿的叶绿素含量在胁迫后期恢复至侵蚀胁迫前期;北沙柳的丙二醛含量随胁迫时间的延长呈先降低后升高趋势,而小叶锦鸡儿的丙二醛含量呈先升高后降低趋势;侵蚀胁迫后期北沙柳和小叶锦鸡儿叶片超氧化物歧化酶活性、过氧化物酶活性和过氧化氢酶活性升高;隶属函数分析显示,在土壤侵蚀环境中,小叶锦鸡儿抗逆性最强,北沙柳次之。【结论】小叶锦鸡儿对采煤沉陷区土壤侵蚀的破坏致损效应具有更好的抵抗力和恢复力,更适于干旱、半干旱矿区的生态修复与植被建设。

不同组合TMR日粮对滩湖杂代羔羊饲喂效果对比分析

试验旨在研究日粮中南瓜籽壳粉、柠条粉、芦苇草粉不同组合对滩湖杂代羔羊生长性能、血液生化指标的影响。选择体重25kg左右、体况较好的断奶公羔羊57只,随机分为3组,每组19只,每只羔羊为1个重复。试验分为前后两期:试验1组试验前期日粮中南瓜籽壳粉、柠条粉、芦苇草粉分别为15%、15%、7%,试验后期分别为15%、10%、5%;试验2组试验前期日粮中南瓜籽壳粉、柠条粉、芦苇草粉分别为10%、11%、14%,试验后期分别为10%、7.5%、11.0%;试验3组试验前期日粮中南瓜籽壳粉、柠条粉、芦苇草粉分别为20%、10%、7%,试验后期分别为20%、7%、3.5%。预试期10d,正式试验期90d。结果显示:各组羔羊末重、平均日增重、平均日采食量、料重比差异均不显著(P>0.05),但以试验1组平均日增重最高,料重比最低。试验2组羔羊血清白蛋白(ALB)、免疫球蛋白M(IgM)含量显著高于其他两组(P<0.05),肌酐(CREA)含量显著高于试验3组(P<0.05)。综合增重情况和饲料成本,试验1组平均日收益最高,试验3组次之,试验2组最低。研究表明,前期以15%南瓜籽壳粉+15%柠条粉+7%芦苇草粉的组合,后期以15%南瓜籽壳粉+10%柠条粉+5%芦苇草粉的组合饲喂滩湖杂代羔羊可提高其平均日增重,增加养殖效益。

柠条收割机圆盘锯式刀片设计与试验

柠条圆盘锯式刀片是收割机的主要零部件之一。在收割运动过程中刀片受力不均匀,且往复循环切割动作导致其易损耗。调研柠条刀片的使用性能及材料特点,研究以特种钢作为刀片基体,在刀刃部表面利用等离子弧熔覆技术进行高合金粉末涂覆,通过优化齿形和热处理工艺参数,获得较优异的耐磨性和强度。经过摩擦磨损试验和作业主体实地收割试验可知,该柠条刀片平茬效果好,使用寿命比同类产品提高了1~2倍。

灌丛化草原小叶锦鸡儿灌丛地上生物量测量方法研究

灌丛化草原已经成为干旱半干旱区的一种重要植被景观类型,在我国以内蒙古草原的小叶锦鸡儿灌丛化现象最为典型。为探索小叶锦鸡儿灌丛地上生物量的最佳测量方法,本研究在锡林郭勒盟镶黄旗和正镶白旗内选取了17个典型样地,对比了“标准枝”和“标准样方”两种直接测量方法获取的地上生物量精度。同时,采用real-time kinematic(RTK)获取到的高度、不规则冠幅面积等4种直接易测因子和衍生的3种复合因子,研究了在无损条件下间接测量地上生物量的可能性,构建了用于研究区小叶锦鸡儿灌丛地上生物量的估测模型。研究结果表明:1)运用“标准枝”法(R=0.95,P<0.01)预测的生物量要比运用“标准样方”法(R=0.84,P<0.01)预测的生物量更精确且对灌丛的损害性更小。2)在易测因子相关性分析中,单因子冠幅、不规则冠幅面积、不规则冠幅周长之间关系紧密,相关性系数均大于0.98(P<0.01),可用于小叶锦鸡儿地上生物量的预测;高度与其他单因子关系一般,相关性系数为0.67~0.72(P<0.05),但是基于高度因子衍生表征体积的冠幅与高度乘积因子、冠幅周长与高度乘积因子、体积因子能够提高预测精度。3)在单因子中冠幅(R=0.92,P<0.01)与生物量表现最好,复合因子中以不规则体积(R=0.92,P<0.01)相关性最高,研究分别以冠幅为自变量建立的线性函数和不规则体积为自变量建立的幂函数构建了小叶锦鸡儿地上生物量预测模型。本研究以期为基于“空-天-地”一体化手段实现大范围灌丛化草原地上生物量遥感估测提供科学参考。

小叶锦鸡儿灌丛地植被对沙源供给的响应

以阴山北麓东段附近的小叶锦鸡儿灌丛地为研究区,在坡积残积地(内源型供给)、洪积扇下风向和农耕地下风向(外源型供给)3个沙源供给有差异的样地,每个样地布设3个样区,每个样区设置3个样方(3个样地共计27个样方),调查样方内小叶锦鸡儿沙堆和堆间地的植被,分析沙源量和沙物质差异供给下的小叶锦鸡儿灌丛地植物群落特征。结果表明:1)三类沙源供给的小叶锦鸡儿灌丛沙堆上群丛类型基本相同,均为小叶锦鸡儿-羊草群丛;2)三类沙源地的灌丛沙堆上物种数均高于堆间地,其中沙源量最大的洪积扇下风向物种数最多;样地间的物种相似度以洪积扇和农耕地下风向间的最高(38%~42%),样地内灌丛沙堆和堆间地上的物种相似度以坡积残积地的最高(80%);3)在三类沙源供给地的灌丛沙堆和堆间地上均出现的植物有6种,即克氏针茅、羊草、糙隐子草、冷蒿、细叶韭、刺沙蓬;4)顺风向随着沙源供给量的增加(坡积残积地)或减少(洪积扇和农耕地下风向),三类样地的堆间地上物种数沿风向均呈现先增加后减少的趋势,灌丛沙丘上则是农耕地和洪积扇下风向靠近沙源区的物种数高于坡积残积地,随沙源量减少其物种数逐渐与坡积残积地的相近。综上,沙源供给量及供给方式对小叶锦鸡儿灌丛地的物种多样性影响较大,而群丛类型几乎不受影响。

载畜率对荒漠草原小叶锦鸡儿邻近土壤速效养分含量的影响

放牧是人类利用草原最主要的方式,可影响土壤的理化性质。小叶锦鸡儿(Caragana microphylla)作为豆科灌木,其邻近土壤养分的变化对会对草地生态系统的结构和功能产生重要的影响。为研究载畜率对荒漠草原小叶锦鸡儿邻近土壤速效养分含量的影响,在内蒙古短花针茅荒漠草原进行放牧实验,共4个载畜率处理(对照CK(0羊单位·hm^(-2)·a^(-1)、轻度放牧LG(0.93羊单位·hm^(-2)·a^(-1))、中度放牧MG(1.82羊单位·hm^(-2)·a^(-1))和重度放牧HG(2.71羊单位·hm^(-2)·a^(-1)),在每个小区中选定大小相近的小叶锦鸡儿植株,分为东南西北4个方向,测定植株邻近土壤碱解氮、速效磷和速效钾含量,分析这些参数之间的变化。结果表明:随载畜率增大,土壤碱解氮含量先升高后降低,速效磷先下降后上升,速效钾含量呈下降趋势。小叶锦鸡儿邻近土壤碱解氮和速效钾含量的平衡点对应的速效磷在LG区呈最小值,土壤速效磷和速效钾含量的平衡点对应的碱解氮在MG区呈最大值。

阴山北麓农牧交错区小叶锦鸡儿地上生物量模型构建

以阴山北麓地区小叶锦鸡儿(Caragana microphylla)人工灌木林为研究对象,在立地和林分调查的基础上,开展小叶锦鸡儿地上生物量预测模型研究,旨在为该区小叶锦鸡儿人工灌木林的抚育管理和资源有效利用提供科学依据。结果表明:平均冠幅(D)和灌丛高×冠幅面积(HC)2个指标作为自变量来拟合小叶锦鸡儿地上生物量效果最佳,预测模型精度检验的总相对误差(RS)、平均相对误差(EE)和平均相对误差绝对值(RMA)均小于20%,生物量模型W=1.150+D^(1.820)和W=1.067+(HC)^(0.785)可作为优化模型来估算阴山北麓地区小叶锦鸡儿的地上生物量。

小叶锦鸡儿(Caragana microphylla)灌丛沙堆形态对沙源供给形式和丰富度的响应

沙源的供给形式和丰富度是控制沙丘形态的直接因子。在内蒙古高原阴山北麓,以洪积扇下风向、农耕地下风向和残积地内的小叶锦鸡儿(Caragana microphylla)灌丛沙堆为研究对象,用典型样方法对沙堆的分布及形态进行系统测量。结果显示:相同样地面积内,相比内源型供给的残积地内的灌丛沙堆,外源型供给的洪积扇和农耕地下风向灌丛沙堆数量少,但单体沙堆的平均尺度大;洪积扇下风向样地沙堆的各项形态参数顺风向急剧递减,残积地内沙堆的水平形态参数顺风向缓慢递增,灌丛及沙堆高度顺风向保持不变,这一结果是对沙源相对位置不同导致沙粒运移方式和沙源量产生差异的响应;内源型、外源型供给的沙堆长、宽间均存在极显著的线性关系(p<0.01),且拟合线斜率均顺风向呈递增趋势,两种供给形式下的沙堆高度与灌丛高度间均存在显著的线性关系(p<0.05),洪积扇下风向和残积地内沙堆的水平尺度与高度间存在极显著的幂函数关系(p<0.01),其中残积地内沙堆水平尺度与高度间的拟合曲线顺风向几乎无变化,洪积扇下风向样地的则顺风向逐步产生差异。