Plant species diversity of wetland ecosystem in an arid and semi-arid region in northwest China

In order to study the changes of plant species diversity along the biotope gradient and its influencing factors in a wetland-arid grassland ecosystem in the arid and semi-arid regions of northwest China, four transect lines were set along the biotope gradient in four directions: east, northeast, west and northwest, and altogether 123 sample plots were investigated on species composition, density, foliage cover, height and biomass (calculated in fresh weight). The whole study area was divided into the wetland zone, the ecotone and the arid grassland zone in terms of habitat characteristics and vegetation types. In this paper, we analyzed and compared the species diversity in the ecotone of a wetland-dry grassland ecosystem in Yanchi County, Ningxia Hui Autonomous Region, with the help of biodiversity software BioDiversity Pro and statistical software Microcal Origin, as well as the combined measurement of species diversity indices. The results revealed distinct differences between those three vegetation zones along each transect line. The ecotone had the highest richness indices (R) and comprehensive diversity indices (Y), reflecting the edge effect. The greatest evenness indices (E) were found in the arid grassland zones. This result agreed with the phenomenon of desertification reversion, vegetation restoration and dominant communities’ formation. As for the four transect lines, the east and the northeast scored higher in each diversity index than the others due to less human disturbance, gentler topography uplift and more intercepted materials and energies. The highest Simpson index value was found in the northeast transect line, which was 39.9% higher than the lowest in the Northwest. Translated from Journal of Beijing Forestry University, 2006, 28(5): 12–17 [译自: 北京林业大学学报]     

三江源草地总生物量对未来气候变化的响应

以青海省三江源为研究区域,利用2005?2016年间采集的2055个草地野外监测数据校正并构建了适用于该地区的DNDC(denitrification-decomposition,反硝化-分解)模型参数库.通过模拟三江源草地总生物量在两种不同代表性浓度路径(RCPs)气候情景下的时空变化,探究了气候因子对草地总生物量变化的影响,并分析了三江源不同区域草地应对未来气候变化的放牧利用对策.研究结果表明:1)草地总生物量的模拟值与实测值呈显著的线性相关(R2=0.690,RMSE=96.414 g·m?2,P<0.001),模型结果能够较好地解释实测数据.2)两种气候情景对比,RCP 8.5气候情景下温度增幅要高于RCP 4.5的气候情景,而降水量增幅则低于RCP 4.5的气候情景.3)在RCP 4.5和RCP 8.5两种未来气候情景下,研究区草地总生物量均呈显著下降趋势,总生物量模拟值分别下降了16.91％～18.51％和23.82％～26.44％.气候变化是导致草地总生物量变化的主要因素,草地管理应积极应对潜在的气候变化并制定相应对策,保障草地资源的可持续发展.     

Agroforestry on alkali soil: effect of planting methods and amendments on initial growth,biomass accumulation and chemical composition of mesquite (Prosopis juliflora (SW) DC) with inter-space planted with and without Karnal grass (Diplachne fusca Linn. P. Beauv.)

Growth responses of mesquite (Prosopis juliflora (SW) DC.) during establishment stage to planting methods and amendments were studied in a highly alkali soil (Aquic Natrustalf, ESP 94), at the experimental farm of the Central Soil Salinity Research Institute, Karnal in July, 1984. Six combinations of planting methods and amendments with and without Karnal grass (Diplachne fusca Linn. P Beauv) in the inter-row space were compared in a four times replicated field experiment in randomised block design. The mean plant height (MPH), diameter at stump height (DSH), diameter at breast height (DBH), lopped biomass 16 months past planting and total biomass attained in 2 years period were significantly less when inter-row space was planted with Karnal grass. The MPH (cm), DSH and DBH (mm) attained in 2 years period were 319, 43.4 and 15.1 in with grass as compared to 405, 53.4 and 20.3 in without grass treatments. Similarly, the total biomass attained in 2 years was about 3 times more where inter-row space was not planted with grass. Growth was better when mesquite was planted by auger hole and pit methods than in trench plantation, when the original soil was treated with gypsum at 3 kg plant^–1 and then refilled. However, using trenches of dimensions 30 × 30 cm and filled with a mixture of original soil, 3 kg gypsum and 8 kg farm yard manure plant^–1 appeared to be promising method for establishing mesquite plantations on highly deteriorated alkali soils. The effect of amendments on growth decreased in the order gypsum + FYM, gypsum + rice husk, gypsum, control. In two years period, 37 percent mesquite died in the trenches in which the original soil was left unchanged. Effect of treatments on nutrient concentrations and total accumulations in different segments of mesquite is discussed. Karnal grass gave 25.3 t ha^–1 green forage yield in 8 cuts without amendment in a growth period of 26 months proving its great potential as a folder crop for the adverse sites. The inorganic chemical composition of the shoots, including trace elements Fe, Mn, Zn and Cu, is such as to make this species a highly promising plant for the exploitation of alkali soils. Growing Karnal grass with mesquite for a period of about 2 years reduced soil pH and EC significantly and improved organic carbon and available N contents. The grass improved water infiltration rates and moisture storage in the lower layers of the profile.     

The Role of Legumes in Plant Community Succession of Degraded Grasslands in Northern China

Legume species were more and more commonly introduced to degraded grassland for human‐aided restoration. This study aimed to test whether the natural spread of legume contributes to reversal of grassland degradation through making an extensive grassland vegetation and soil survey in Inner Mongolia of China. The results showed that legume biomass increased along a gradient of soil coarsening that was also a gradient of grassland degradation. The total biomass rather than legume biomass was limited by mean annual precipitation at plot level. The presence of legumes increased species richness in degraded steppe vegetation. Constancy of intermediate and climax species of vegetation succession at sites with legumes was higher than that at sites without legumes, implying that legumes might contribute positively to the reversal of grassland degradation. Our study suggests that naturally distributed legumes could benefit the reversal of grassland degradation through promoting plant community succession rather than total plant biomass. Planting legumes would be an effective measure to accelerate the recovery process of degraded grassland with coarsened soil in regions similar to our study region. Copyright © 2015 John Wiley & Sons, Ltd.     

‘阿尔冈金’紫花苜蓿在甘肃夏河地区产量和品质特性研究及综合评价

优质豆科牧草选育和栽培对于高寒地区畜牧业发展具有重要意义。‘阿尔冈金’紫花苜蓿(Medicago sativa‘Algonguin’)是耐寒性较强的优质豆科牧草,在高山草原适应性较强,在该区对其进行产量和营养品质动态研究,有利于当地高品质饲草的生产和利用。本研究在甘肃夏河地区通过田间试验,对‘阿尔冈金’在不同生长时期的干草产量和粗蛋白(CP)、粗脂肪(CF)、可溶性糖(WSC)、灰分(ASH)含量和矿物元素含量的动态变化进行了研究。结果表明,‘阿尔冈金’草产量随着生长逐渐增加,而CP和CF含量在生长前期较高,生长后期逐渐降低。WSC含量随着生长先降低后增加。ASH和矿物元素含量在各生长时期的变化规律有所不同,ASH含量随着生长呈"N"变化规律,元素P、K和Na为直线型,Ca、Mg和Mn为正抛物线型,Cu和Zn为反抛物线型。从饲用角度看,各刈割期的CP含量均达到美国一等饲草标准;盛花期干草产量最高;各生长时期易消化性营养成分含量适中;矿物元素中,除Cu外,能够基本满足草地家畜对P、K、Na、Ca、Mg、Mn和Zn元素的营养需求。因此综合考量,‘阿尔冈金’是夏河地区适宜推广种植的豆科牧草,建议在盛花期对其进行收割,此时利用价值最高。     

施肥和混播对松嫩平原退化草地土壤和牧草产量的影响

[目的]研究施肥和混播牧草对松嫩平原黑龙江省西部退化草地土壤养分和牧草产量的影响,为该区天然退化草地修复提供科学依据。[方法]试验以黑龙江省西部天然轻度退化草地为研究对象,沙打旺(Astragalus adsurgens)和披碱草(Elymus dahuricus)为补播草种,设2个间行混播[豆禾比2∶2(B₁)和1∶2(B₂)]和6个水平氮磷钾施肥组合[N₅₀P₄₀K₄₅(A₁),N₁₀₀P₂₄₀K₂₂₅(A₂),N₁₅₀P₀K₁₈₀(A₃),N₂₀₀P₁₂₀K₀(A₄),N₂₅₀P₈₀K₂₇₀(A₅),N<...     

豆科灌木－小叶锦鸡儿在我国北方半干旱沙地中的作用

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.     

放牧和光照对林下栽培草地生产力的影响

研究了不同放牧强度G0(0只/hm2)、G1(22.2 只/hm2)、G2(44.4只/hm2)和不同光照条件(100%光强、68.83%光强和54.29%光强)对香樟(Cinnamomum camphora)林下混播草地生产力的影响.结果显示,在整个生长季,草地现存量、再生量和净初级生产力在同一放牧强度下均呈现随光照...     

青海省三江源地区退化草地蒸散特征

了解三江源地区退化草地的蒸散状况有助于认识该地区退化生态系统水循环,对该地区的生态安全有着重要的意义。本研究利用涡度相关法观测青海省玛沁县小嵩草退化草地（３４．３５°Ｎ;１００．５０°Ｅ,海拔３９６３ｍ）的水热通量,对该地区２００６－２００８年全年的蒸散情况进行了特征分析。研究表明,２００６－２００８年三江源退化草地的蒸散值分别为４５２．２４,４７４．２４,４５９．５７ｍｍ,降水量分别为４６０．７,４９６．１,４８０．１ｍｍ,其中有７５％以上的降水分布在生长季,全年水平上蒸散量与降水量之比（ＥＴ／ＰＰＴ）为９５％ 以上,蒸散量与降水量基本持平。生长季日蒸散量１．８～１．９ｍｍ／ｄ,而非生长季日蒸散量＜０．６ ｍｍ／ｄ。蒸散日变化和年变化均为单峰型,每年６－７ 月蒸散量最大,为２．０～２．２ｍｍ／ｄ;日蒸散峰值出现在正午左右,其最大值生长季为０．２１ｍｍ／ｈ,非生长季为０．１０ｍｍ／ｈ。退化草地蒸散的主要环境因子是净辐射,其次为饱和水汽压亏和空气温度。随着生长季的推进,潜热对这些因素的敏感性逐渐增大。与未退化的矮嵩草草甸相比,退化草地生长季蒸散量较小,而非生长季蒸散量较大,这一结果表明,高寒草地的植被盖度驱动草地生态系统的蒸散。     

甘南高寒草原面临的问题及对策

草原高寒资源是大自然的主体部分之一,是人类赖以生存和发展的物质基础,是维护生态平衡的重要环节。甘南草原是长江、黄河上游重要的水源补给和涵养区,在中国西部生态环境系统中处于十分重要的位置。保护和建设好甘南草原,不仅影响广大农牧民赖以生存的基本生产、生活资料,而且也维系着黄河、长江中下游地区的生态安危。