黄土高原适生树种苗木的耗水特性

黄土高原适生树种苗木的耗水特性韩蕊莲,梁宗锁,侯庆春,邹厚远（中国科学院西北水土保持研究所,杨陵７１２１００）ＷａｔｅｒｃｏｎｓｕｍｐｔｉｏｎｐｒｏｐｅｒｔｉｅｓｏｆａｄａｐｔａｂｌｅｎｕｒｓｅｒｙｓｔｏｃｋｓｏｎＬｏｅｓｓｐｌａｔｅａｕ￥ＨａｎＲｕ...     

黄土高原林草水土保持有效盖度分析

根据黄土高原缓德,延安、安寨和离石等地林、草地径流小区降雨侵蚀资料,对不同降雨和坡度下林、草地水土保持有效盖度进行了分析,建立了林地、草地水保持临界有效盖度与降雨坡度的关系式,在土壤和植被类型相对稳定的条件下,林、草地的有效盖度随着降雨和坡度的增大而增大,当临界有效盖度达到一定程度时,降雨和坡度的影响减弱;在其它条件相同时,同一水土保持作用所需求的有效盖度草地比林地大。并结合降雨频率分析,得出了林     

青海高原不同海拔珠芽蓼叶绿体超微结构的比较

 用电子显微镜技术观察研究了生长于青海高原3个海拔地带(2500m、3200m、3980m)的珠芽蓼(polygonum viviparum L．)叶绿体的超微结构,发现随着海拔的升高,叶绿体结构呈现显著的变化趋势。2500m和3200m处叶绿体形状规则,分布在细胞边缘。3980m处叶绿体膨大变形,且分布在整个细胞当中。海拔升高,类囊体膜减少,膜垛叠程度减小。不同海拔珠芽蓼叶绿体的类囊体膜结构差异较大,特点显著。随海拔升高,珠芽蓼叶绿体破坏程度增加。主要表现为类囊体膜肿胀、类囊体膜溶解和叶绿体破裂。许多破裂的叶绿体中残留有发达的基粒和大而多的淀粉粒。珠芽蓼叶绿体的这些结构特征,既是环境胁迫的结果,又是植物适应性的表现。     

Response of Seedlings of Three Dominant Shrubs to Climate Warming in Ordos Plateau

Ordas plateau is a classical semi-dry sandland in China. The dry ecosystem responds sensitively to water-heat pattern of global change there. The distribution pattern and productivity of terrestrial ecosystem are greatly affected by global warming. Ecological adaptation strategies of seedlings of Caragana　intermedia Kuang et H. C. Fu, Hedysarum mongolicum Turcz. and Artemisia ordosica Kraschen.,three dominant shrubs in Ordas plateau, were investigated in terms of morphological plasticities, biomass effects and photosynthetic and physiological characters, to the global warming by artificially controlling two temperature levels. The results show that the effects of temperature enhancement on growth and photosynthetic and physiological characters were obviously different among these three plant species. Temperature enhancement significantly increased tree height, leaf number, leaf area, biomass, photosynthetic rate, transpiration rate and stomatal conductance of C. intermedia and H. mongolicum seedlings, indicating that elevated temperature significantly affected the growth of these seedlings positively. Elevated temperature had almost no significant effect on the growth of A. ordosica seedlings. Their leaf number, leaf size, leaf area, biomass, transpiration rate and stomatal conductance did not increase obviously, but tree height and photosynthetic rate obviously increased with increasing temperature. Interspecific growth was significantly different among C. intermedia, H. mongolicum and A. ordosica seedlings. Except leaf size, values of the other seven characters of C. intermedia seedlings were greater than those of H. mongolicum and A. ordosica seedlings.     

近50年冀北高原土地利用变化的土壤生境效应

区域性土壤生境的变化,很大程度上取决于该区土地利用及其覆被的变化．通过冀北高原近50年不同时段的资料分析证实,大片天然草场无序垦为耕地的利用变化及伴随的管理粗放,致土壤生境发生系列负面效应,土壤养分逐年下降．50年中,该区土壤有机质,N、P、K全量及速效态量分别以36．90％、67．77％、44．44％、34．15％、32．22％、58．90％、35．29％的降幅趋势性地下降;砂、粉、粘三项表征土壤物性特征的不同土粒含量则以18．24％、19．55％和12．29％升降皆有的幅度变化．这一结果揭示,为确保区位重要、生境脆弱区的土地质量不因利用变化和随时间推移而下降,永续处于动态平衡,务必科学管理,技术举措到位。     

西藏高原天然长芒草地丛枝菌根真菌接种效应

采用草地均匀打孔方法,就草地土壤未消毒条件下接种丛枝菌根（AM）真菌对长芒草(Stipa bungeana)的侵染效应以及对植物生长、吸磷效率、土壤微生物区系等的影响进行研究.结果表明,1)接种处理、不接种处理的菌根效应存在着明显的差异,多数接种处理根围土壤AM真菌孢子密度、菌根侵染率和侵染强度显著提高,但对丛枝丰度的影响相对较低.2)接种后AM真菌孢子密度对菌根侵染率具有极显著影响(r=0.7679**);随菌根侵染率的增加,植株总干物重和吸磷总量均呈极显著提高,r值分别为0.7556**、0.8018**.3)与植株地上部相比,接种AM真菌对提高根系干物重、根系吸磷量和含磷量的促进作用相对较大.4)多数接种处理根际土壤酸性磷酸酶、碱性磷酸酶活性均呈一定程度的提高,根际土壤细菌数量显著增加,真菌、放线菌的数量变化则不甚明显.5)各接种处理对寄主植物的综合侵染效应在总体上呈Glomus mosseae+G. intraradices+Scutellospora calospora＞G. mosseae+G. aggregatum＞Glomus sp.＞G. mosseae＞G. mosseae+ G. etunicatum+G. intraradices+S. erythropa＞G. geosporum的趋势.     

Modelled mid-trophic pelagic prey fields improve understanding of marine predator foraging behaviour

Biophysical interactions are influential in determining the scale of key ecological processes within marine ecosystems. For oceanic predators, this means foraging behaviour is influenced by processes shaping the distribution of prey. However, oceanic prey is difficult to observe and its abundance and distribution is regionally generalised. We use a spatiotemporally resolved simulation model to describe mid-trophic prey distribution within the Southern Ocean and demonstrate insights that this modelled prey field provides into the foraging behaviour of a widely distributed marine predator, the southern elephant seal. From a five-year simulation of prey biomass, we computed climatologies of mean prey biomass (average prey conditions) and prey biomass variability (meso-scale variability). We also compiled spatially gridded metrics of seal density and diving behaviour from 13 yr of tracking data. We statistically modelled these metrics as non-linear functions of prey biomass (both mean and variability) and used these to predict seal distribution and behaviour. Our predictions were consistent with observations (R²_adj = 0.23), indicating that seals aggregate in regions of high mesoscale activity where eddies concentrate prey. Here, seals dived deeper (R²_marg = 0.12, R²_cond = 0.51) and spent less time hunting (R²_marg = 0.05, R²_cond = 0.56), likely targeting deep but profitable prey patches. Seals generally avoided areas of low eddy activity where prey was likely dispersed. Most seals foraged south of the Subantarctic Front, despite north of the front exhibiting consistently high simulated prey biomasses. This likely reflects seal prey or habitat preferences, but also emphasises the importance of mesoscale prey biomass variability relative to regionally high mean biomass. This work demonstrates the value of coupling mechanistic representations of prey biomass with predator observations to provide insight into how biophysical processes combine to shape species distributions. This will be increasingly important for the robust prediction of species’ responses to rapid system change.     

Molecular phylogeography and intraspecific divergence of Spiraea alpina (Rosaceae) distributed in the Qinghai-Tibetan Plateau and adjacent regions inferred from nrDNA

The Qinghai-Tibetan plateau (QTP) uplift had a decisive effect on climatic and eco-environmental evolution in East Asia during the Quaternary. In the current study phylogeographic structure and diversification history of Spiraea alpina across the QTP were investigated for the first time based on nuclear internal transcribed spacer. The nuclear internal transcribed spacers (ITS_1a–ITS₄) were generated for a total of 284 individuals distributed within 31 natural populations. A clear phylogeographic structure was found for S. alpina. The results showed that this species colonized in three different glacial refugia during the Quaternary extensive glaciation and expanded during the Interglacial period. Analysis of molecular variance (AMOVA) showed 74.13% genetic diversity among populations and 25.87% genetic variation within populations with distinct phylogeographic structure (F_ST = 0.741*). The estimated divergence time revealed that the main lineages of S. alpina diversified during the Quaternary 1.2–0.6 million years ago. The study concluded that severe climatic oscillations during Quaternary and the uplift of QTP had a profound effect on intraspecific divergence of S. alpina.     

黄土高原羊圈沟小流域土地利用时空变化的土壤有机碳效应

土地利用变化是影响土壤有机碳储量和分布变化的重要驱动因素,为进一步探讨土地利用变化对土壤有机碳的影响,根据土壤样点数据、土地利用类型图,分析了黄土丘陵沟壑区羊圈沟小流域2006—2011年土地利用变化及其对表层土壤有机碳密度和储量的影响,主要结论如下:(1)小流域土地利用发生较大变化,主要集中在乔木林地和灌木林地面积的增加,分别为39.697、46.404 hm2;以及草地面积的减少,为64.030 hm2;(2)土地利用方式的变化会导致土壤有机碳密度及储量的变化,其中转变用地类型的土壤有机碳储量增加587.25 kg,以荒草地转出类型增加的土壤表层有机碳储量最多,为441.64 kg;灌木林地转出类型减少的土壤表层有机碳储量最多,为-21.01 kg。草地-灌木林地、草地-乔木林地、坡耕地-草地、坡耕地-灌木林地、坡耕地-乔木林地、坡耕地-坝地、梯田-草地、梯田-灌木林地、梯田-乔木林地、梯田-坝地、坝地-草地、坝地-灌木林地、坝地-乔木林地等转换用地类型的表层土壤碳密度增加值高于保持用地类型碳密度的增加值,说明这些地类的转换有利于表层土壤有机碳储量的增加,即有利于表层土壤碳汇的形成;而其他地类转换造成了表层土壤的碳排放,应该引起足够的重视;(3)土壤固碳应着眼于长期效应,频繁的土地利用类型转化可能会降低土壤碳截流效果,黄土丘陵区植被重建的长期利用和保持更有利于土壤有机碳的积累。     

Beta- and Novel Delta-Coronaviruses Are Identified from Wild Animals in the Qinghai-Tibetan Plateau,China

Outbreaks of severe virus infections with the potential to cause global pandemics are increasingly concerning. One type of those commonly emerging and re-emerging pathogens are coronaviruses(SARS-Co V, MERS-Co V and SARS-Co V-2).Wild animals are hosts of different coronaviruses with the potential risk of cross-species transmission. However, little is known about the reservoir and host of coronaviruses in wild animals in Qinghai Province, where has the greatest biodiversity among the world's high-altitude regions. Here, from the next-generation sequencing data, we obtained a known beta-coronavirus(beta-Co V) genome and a novel delta-coronavirus(delta-Co V) genome from faecal samples of 29 marmots, 50 rats and 25 birds in Yushu Tibetan Autonomous Prefecture, Qinghai Province, China in July 2019. According to the phylogenetic analysis, the beta-Co V shared high nucleotide identity with Coronavirus HKU24. Although the novel delta-Co V(Mt Co V) was closely related to Sparrow deltacoronavirus ISU42824, the protein spike of the novel delta-Co V showed highest amino acid identity to Sparrow coronavirus HKU17(73.1%). Interestingly, our results identified a novel host(Montifringilla taczanowskii) for the novel delta-Co V and the potential cross-species transmission. The most recent common ancestor(t MRCA) of Mt Co Vs along with other closest members of the species of Coronavirus HKU15 was estimated to be 289 years ago. Thus, this study increases our understanding of the genetic diversity of beta-Co Vs and deltaCo Vs, and also provides a new perspective of the coronavirus hosts.