Long-term spatial and temporal variation of CO2 partial pressure in the Yellow River, China

10.5194/bg-12-921-2015Biogeosciences124921-93

The Biogeographic Pattern of Microbial Functional Genes along an Altitudinal Gradient of the Tibetan Pasture

As the highest place of the world, the Tibetan plateau is a fragile ecosystem. Given the importance of microbial communities in driving soil nutrient cycling, it is of interest to document the microbial biogeographic pattern here. We adopted a microarray-based tool named GeoChip 4.0 to investigate grassland microbial functional genes along an elevation gradient from 3200 to 3800 m above sea level open to free grazing by local herdsmen and wild animals. Interestingly, microbial functional diversities increase with elevation, so does the relative abundances of genes associated with carbon degradation, nitrogen cycling, methane production, cold shock and oxygen limitation. The range of Shannon diversities (10.27–10.58) showed considerably smaller variation than what was previously observed at ungrazed sites nearby (9.95–10.65), suggesting the important role of livestock grazing on microbial diversities. Closer examination showed that the dissimilarity of microbial community at our study sites increased with elevations, revealing an elevation-decay relationship of microbial functional genes. Both microbial functional diversity and the number of unique genes increased with elevations. Furthermore, we detected a tight linkage of greenhouse gas (CO2) and relative abundances of carbon cycling genes. Our biogeographic study provides insights on microbial functional diversity and soil biogeochemical cycling in Tibetan pastures

Rangeland Degradation: Causes, Consequences, Monitoring Techniques and Remedies

Rangelands occupy 25% of the total land surface globally. In Africa, rangelands are estimated to cover 66% of the land surface, although there are variations from country to country. In Eastern Africa, for example, land surface coverage of rangeland areas varies from 44% in Uganda and 65% in Ethiopia to 74% in Tanzania and over 80% in Kenya. Rangelands have environmental, social and economic benefits, including support to national economies through tourism and employment. In Kenya, tourism, much of which is attributed to rangelands, accounts for 13% of the gross domestic product. In Tanzania, tourism contributed 9.0% of the total GDP, supporting 26% of total exports, 8.2% of the total employment, and 8.7% of total investment in the year 2017. Despite their benefits, rangelands are under threat of continued degradation driven by anthropogenic and natural causes. Natural causes of rangeland degradation include climate change and variabilities, aridity and desertification, drought, as well as alien species invasion. Anthropogenic rangeland degradation can manifest through agricultural activities and associated developmental practices, overstocking and overgrazing, as well as breakdown of social structures and government policies/by-laws. Continuous overgrazing and overstocking not only affect soil physical (compaction, breakdown of aggregates) but also chemical (soil pH and salinization, nutrient leaching, diminishing organic matter content), and biological properties. These decrease rangeland production potentials. However, numerous strategies to arrest and remedy rangeland degradation, such as rangeland re-vegetation, water harvesting, soil surface scarification, and livestock grazing management are available. This report addresses rangeland degradation and potential control measures with a strong focus on soil aspects

Pedogenesis, Permafrost, and Ecosystem Functioning: Feedbacks and Interactions along Climate Gradients across the Tibetan Plateau

This thesis was conducted within the scope of a graduation fellowship from the state of Baden-Württemberg, Germany (Grant No.: VI 4.2-7631.2/Baumann) in cooperation with the Depart-ment of Ecology, Peking University, Beijing. Scientists specialised in both ecology and soil science investigated the same sites, thus allowing an interdisciplinary approach to evaluate soil properties, C and N cycles as well as geomorphological processes in close connection to ecosys-tem interrelations on the Tibetan Plateau. The research sites are located along a 1,200 km long north-south transect at altitudes between 2,925 and 5,105 m ASL. Two thirds of the Tibetan Plateau is influenced by permafrost. Due to the high sensitivity to global climate warming and land use changes, permafrost degradation processes are widespread, increasing the heterogeneity of soil formation, soil hydrology, and related soil chemical processes (i.e. C and N cycling). In order to account for the resulting extremely diverse ecosystem, investigations at different spatial scales related to large-scale climate patterns were performed. The scales comprise the total main transect, the split transect into an eastern and western section, diverse catenas along distinct geomorphological relief units, and finally the single site soil profiles. The first part of this work examines C and N contents as well as portions of plant available min-eralised nitrogen in relation to their main influencing parameters. For investigations on land-scape scale, soil moisture was found to have the strongest effect on C and N cycling, followed by CaCO3-content and soil texture. Altogether, the general linear model explains 64% and 60% of the variation of soil organic carbon (SOC) and total nitrogen (NT) contents, respectively. Thereby, two aspects are important: (1) temperature variables have no significant influence and (2) indicators for soil development (i.e. CaCO3 and soil texture) are included besides commonly con-sidered ecological (i.e. moisture, temperature and biomass) parameters. It could be shown that in the highly diverse permafrost-affected ecosystem of the Tibetan Plateau, other factors than precipitation mainly control soil moisture contents and distribution, with permafrost and relief position being the most dominant parameters. Since pedogenic parameters turned out to be important predictors, the degree of soil development can be regarded as an additional control quantity, indicating higher C and N contents of topsoils with longer duration of undisturbed and stable soil development. Mineralised plant available N can be almost exclusively found as am-monium-N, which is closely related to higher soil moisture contents and frigid climate condi-tions, showing by far the highest contents in the permafrost main soil group. As nitrification is strongly temperature dependent, nitrate-N contents are correspondingly very low. The results provide clear evidence that limitation in plant available nutrients as a negative feedback to lower soil moisture is crucial for plant growth in nutrient-limited alpine grassland ecosystems, even though higher temperatures occur with respect to climate warming. Importantly, these strong feedback mechanisms between altering permafrost conditions (degradation and higher active layer thickness) and hence reverse influence of rising temperatures (further decay of permafrost and related dryer conditions) could be only detected by conducting this study on landscape scale. These dependencies are based on the overall limitation of moisture, because evaporation exceeds precipitation by far at all investigated sites. Degraded permafrost profiles show low C and N contents combined with distinct depth patterns, mainly caused by higher mineralisation rates and deposition of proximal airborne sediments. This is can be exemplarily shown for the Shule River basin located at the very north-eastern margin of the Tibetan Plateau, where soils under desert-type vegetation have their highest SOC density in soil depths between 20 and 40 cm, but not in the top 20 cm as evident for all other vegetation types. The main reason for these patterns are most likely such syngenetic soil forming processes. Results of soil respiration measurements basically confirm the findings observed for C and N contents. Belowground biomass and soil moisture explain 82% of the variation, whereas no direct effects of temperature could be described. Respiration values of alpine meadows were 2.5 times higher than of alpine steppes, which is a consequence of higher biomass and productivity in alpine meadows. Besides the relations to control variables, SOC was further analysed with regard to its stocks and composition. The comparison of two main investigation sites for discontinuous and continuous permafrost, respectively, clearly shows higher SOC stocks for discontinuous (10.4 kg m-2) than for continuous permafrost (3.4 kg m-2). Highest values occur at water-saturated profiles (19.3 kg m-2), causing positive feedbacks to even higher SOC accumulation, if in turn denser vegetation isolates the soil. At the same time, these soils contain substantial higher portions of easily de-composable particulate organic matter fractions, which are especially vulnerable to climate change owing to shorter turnover rates. The colder and dryer climate in continuous permafrost areas leads to a lower productivity and an allocation of belowground biomass mainly in the top 10 cm. This can be approved by studies conducted in the Shule River basin, also characterised by low mean annual temperature and precipitation, showing average SOC stocks of 7.7 kg m-2. Moreover, different vegetation types can be distinguished very clearly, ranging from 4.4 kg m-2 under desert vegetation to 19.8 kg m-2 under partly water-saturated alpine swamp meadow (cf. above-mentioned corresponding respiration rates related to vegetation type patterns). Moreover, it could be shown that soil inorganic carbon (SIC) and SOC are influenced by different parameter sets. Whereas soil physical and chemical properties are most appropriate to describe SIC, biotic and climatic factors are more important for SOC. Soil pH was found to predict 42% of SIC variation, leading to lower contents with decreasing pH. However, the overall effect of the released carbon under scenarios of potential soil acidification is assumed to be compensated, since SOC reacts vice versa to increased soil acidity. Since pedological processes proved to have significant influence on C and N contents, it is im-portant to specifically qualify related weathering and sedimentation processes depending on the state of permafrost as well as land surface stability. To address this issue, weathering indices and pedogenic Fe-oxides were applied to particular sampling groups, distinctly influenced by the Indian and Asian Monsoon systems. The chemical index of alteration (CIA) represents the most useful weathering index, best describing large scale climate trends, varieties of substrates, and specific permafrost patterns. For pedogenic Fe-oxides, (Fed-Feo)/Fet ratio best illustrates small-scale shifts of pedogenesis. This can be confirmed by the differentiability of the main soil groups, which cannot be obtained by CIA. Essentially, groundwater and permafrost influenced soils can be clearly distinguished by distinct parameter sets best explaining each soil group: climate pa-rameters for the permafrost soil group (climate-zonal soil formation), and site-specific variables for groundwater-influenced soils (azonal soil formation). Moreover, the two soil groups can be significantly differentiated by Fep, even though both show high soil moisture and SOC contents. Therefore it can be assumed, that particular redoxi-morphic and soil formation processes with corresponding soil organic matter structures evolve under the influence of permafrost. Alto-gether, the application at various spatial scales give strong evidence that weathering indices and pedogenic Fe-oxides are useful tools to depict states of permafrost distribution and its degrada-tion features. Summarising, the described geochemical patchwork (manuscripts 1-5) can be disentangled by applying weathering indices and pedogenic oxides ratios, depending on the scale and process. Together with the evaluation of the prevailing main influencing parameters, they proved to be crucial for assessing C and N cycles and ecosystem functioning on the Tibetan Plateau.Die vorliegende Arbeit wurde im Rahmen eines Stipendiums der Landesgraduiertenförderung Baden-Württemberg (Förderungs-Nr.: VI 4.2-7631.2/Baumann) in Zusammenarbeit mit der Fakultät für Ökologie der Peking University erstellt. Somit waren interdisziplinäre Untersuchun-gen von Bodeneigenschaften, C- und N-Kreislauf, geomorphologischen Prozessen sowie die di-rekte Analyse der Wechselbeziehungen dieser Parameter zum Gesamtökosystem des Tibetischen Hochplateaus möglich. Die Forschungsstandorte liegen entlang eines 1200 km langen nord-süd verlaufenden Transekts in Höhen zwischen 2925 und 5105 m ü. NN. Ungefähr zwei Drittel des Tibetischen Hochplateaus sind durch Permafrost beeinflusst und entsprechend besonders empfindlich im Hinblick auf Klimawandel und Landnutzungswechsel. Folglich sind häufig großräumige Degradationsprozesse zu beobachten. Dies führt zu einer steigenden Heterogenität der Bodenbildung, Bodenhydrologie und nachgeordneten bodenchemischen Prozessen, deren wichtigster Bestandteil der C- und N-Kreislauf ist. Um dem resultierenden, extrem diversen Ökosystem in seiner gesamten Breite gerecht zu werden, wurden Analysen auf verschiedenen räumlichen Maßstabsebenen entlang von Klimagradienten durchgeführt. Die Maßstabsebenen umfassen den gesamten Haupttransekt, einen östlichen und westlichen Teiltransekt, diverse Catenen entlang bestimmter geomorphologischer Reliefeinheiten und die Einzelstandorte. Zunächst wurden C- und N-Gehalte sowie die Anteile pflanzenverfügbaren Stickstoffs in Verbin-dung mit deren Haupteinflussparametern untersucht. Auf Landschaftsebene hat Bodenfeuchte den größten Einfluss auf die C- und N-Gehalte, gefolgt von CaCO3 und der Korngrößenverteilung. Insgesamt erklärt das lineare Regressionsmodell 64% der Variation von organischen Bodenkoh-lenstoffgehalten (SOC) und 60% in Bezug auf den Gesamtstickstoff (TN). Dabei ist zweierlei maßgeblich: (1) Temperaturvariablen haben keinen signifikanten Einfluss, während (2) Indika-toren der Bodengenese, wie CaCO3-Gehalt und Korngrößenverteilung neben herkömmlichen ökologischen Variablen, wie beispielsweise Feuchtigkeitsparameter oder Biomasse, in das Re-gressionsmodell aufgenommen werden. Entsprechend wird in den hoch komplexen, periglazial geprägten Ökosystemen des Tibetischen Hochplateaus die Bodenfeuchteverteilung nicht direkt durch den Niederschlag, sondern vielmehr durch die auf indirektem Wege agierenden Parameter Reliefposition und Permafrost kontrolliert. Da sich bodenkundliche Einflussgrößen als wichtige Prädiktoren herausgestellt haben, kann der Grad der Bodenentwicklung allgemein als eine zusätzliche Stellgröße betrachtet werden: Je länger eine ungestörte und stabile Pedogenese vor-liegt, desto höhere C- und N-Gehalte sind zu beobachten. Dies betrifft auch den mineralisierten pflanzenverfügbaren Stickstoff, der fast ausschließlich als Ammonium-N vorliegt, was wiederum eng an erhöhte Bodenfeuchte und kühle Klimaverhältnisse geknüpft ist. Dabei treten die mit Abstand höchsten Werte in der Hauptbodengruppe „Permafrost“ auf. Entsprechend weist Nitrat-N sehr geringe Gehalte auf, da Nitrifikationsprozesse stark temperaturabhängig sind. Die Ergeb-nisse liefern einen klaren Nachweis dafür, dass eine Limitierung pflanzenverfügbarer Nährstoffe als negative Rückkopplung aufgrund geringerer Bodenfeuchtewerte trotz potenziell steigender Temperaturen im Hinblick auf die globale Erwärmung hervorgerufen werden kann. Die ausge-prägten Rückkopplungsmechanismen zwischen Veränderungen des Permafrosts (Degradations-prozesse und größere Mächtigkeit des Active Layers) und infolgedessen eines umgekehrten Ein-flusses steigender Temperatur (weiterer Rückgang von Permafrost und damit verbundene tro-ckenere Bedingungen) konnten ausschließlich aufgrund des gewählten Maßstabs auf Land-schaftsebene ermittelt werden. Diese Abhängigkeiten basieren auf der negativen Feuchtigkeits-bilanz des Untersuchungsgebietes, da die Evaporation bei weitem die Niederschlagswerte über-steigt. Die niedrigen C- und N-Gehalte sowie die spezifische Tiefenverteilung an degradierten Standorten sind hauptsächlich auf höhere Mineralisationsraten und die Ablagerung von proximal generierten äolischen Sedimenten zurückzuführen. Dies kann exemplarisch für das Einzugsgebiet des Shule River am nordöstlichen Rand des Tibetischen Hochplateaus aufgezeigt werden, wo Böden unter Wüstenvegetation nicht wie alle anderen Vegetationstypen die höchsten SOC-Gehalte in den ersten 20 cm, sondern vielmehr in Bodentiefen zwischen 20 und 40 cm aufweisen. Hauptgrund hierfür sind ebendiese synsedimentären Bodenbildungen. Ergebnisse von Bo-denrespirationsmessungen bestätigen grundsätzlich die für C und N-Gehalte gemachten Be-obachtungen. Unterirdische Biomasse und Bodenfeuchte erklären 82% der Gesamtvariation, wobei kein direkter Einfluss von Temperatur nachgewiesen werden konnte. Die Bodenrespira-tion alpiner Matten übersteigt aufgrund der höheren Biomasse und Produktivität die von alpiner Steppenvegetation um das 2,5-fache. Neben den Beziehungen mit Kontrollvariablen wurde SOC zusätzlich im Hinblick auf Vorräte und Zusammensetzung untersucht. Der Vergleich zwischen den Hauptuntersuchungsstandorten erbrachte deutlich höhere SOC-Vorräte für diskontinuierlichen Permafrost (10.4 kg m-2), wäh-rend im kontinuierlichen Permafrost lediglich durchschnittlich 3.4 kg m-2 ermittelt wurden. Höchste Vorräte finden sich in wassergesättigten Profilen (19.3 kg m-2), da die Isolationswirkung der dichteren Vegetation einen positiven Rückkopplungsmechanismus auslösen und zu einer weiteren Akkumulation von SOC führen kann. Gleichzeitig enthalten diese Böden im Bereich des diskontinuierlichen Permafrosts höhere Anteile an vergleichsweise leicht abbaubaren Fraktionen partikulärer organischer Substanz, die entsprechend anfällig auf Klimaveränderungen reagiert. Die kühleren und trockeneren Verhältnisse im Bereich des kontinuierlichen Permafrosts führen hingegen zu einer geringeren Produktivität und einer schwerpunktmäßigen Verteilung der unterirdischen Biomasse in den obersten 10 cm. Dies kann zusätzlich durch Untersuchungen im ebenfalls durch niedrige Jahresdurchschnittstemperaturen und Niederschlägen geprägten Einzugsgebiet des Shule River nachgewiesen werden. Hier finden sich durchschnittliche SOC-Vorräte von 7.7 kg m-2, die je nach Vegetationseinheit zwischen 4.4 kg m-2 unter Wüstenvegeta-tion und 19.8 kg m-2 unter wassergesättigten alpinen Sumpfmatten variieren (vgl. oben be-schriebene Respirationswerte in Bezug auf verschiedene Vegetationsmuster). Ferner konnte gezeigt werden, dass anorganischer Kohlenstoff (SIC) und SOC durch unter-schiedliche Parametersets beeinflusst werden: Bodenphysikalische und bodenchemische Eigen-schaften beschreiben SIC am besten, während biotische und klimatische Faktoren für SOC rele-vanter sind. Ein niedrigerer pH-Wert führt demnach zu geringeren SIC-Gehalten und erklärt 42% der Variation. Jedoch kann im Hinblick auf potentielle Bodenversauerung die Kohlen-stofffreisetzung aufgrund der umgekehrten Reaktion von SOC kompensiert werden. Da ein signifikanter Einfluss bodenbildender Prozesse auf C- und N-Gehalte nachgewiesen wer-den konnte, ist es notwendig damit verbundene Verwitterungs- und Sedimentationsprozesse in Bezug auf Permafrostverteilung und Oberflächenstabilität zu analysieren. Hierfür wurden Ver-witterungsindizes und pedogene Fe-Oxide auf verschiedenen Maßstabsebenen und Untergruppen in Bezug auf spezifische klimatische Verhältnisse angewendet. Der „chemical index of alteration“ (CIA) eignet sich dabei am besten um großräumige Klimatrends, Substratunterschiede und spezifische Permafrostverteilungsmuster zu beschreiben. Dagegen zeigen Quotienten pedogener Fe-Oxide kleinräumige bodengenetische Wechsel an, wofür sich vorzugsweise (Fed-Feo)/Fet bewährt hat. Dies kann durch die klare Differenzierbarkeit von Hauptbodengruppen, die durch den CIA nicht möglich ist, untermauert werden. Dabei ist wesentlich, dass Böden, die durch Grundwasser und Permafrost beeinflusst sind, klar zu unterscheiden sind. Klimaparameter haben innerhalb der Hauptbodengruppe „Permafrost“ das größte Gewicht (klimazonale Bodenbildung), während standortspezifische Variablen den Haupteinfluss innerhalb von Grundwasser geprägten Böden aufweisen (azonale Bodenbildung). Zusätzlich können diese Bodengruppen statistisch signifikant durch Fep unterschieden werden, obwohl sie ähnlichen SOC-Gehalten und Bodenfeuchteverhältnissen unterliegen. Folglich entsteht in Permafrost beeinflussten Böden aufgrund bestimmter redoximorpher und bodenbildender Prozesse organische Substanz mit spezifischen Strukturen und Eigenschaften. Insgesamt erweisen sich Verwitterungsindices und pedogene Fe-Oxide als vielversprechende Werkzeuge um diverse Stadien des Permafrosts, des-sen räumliche Verteilung und Fragen der Oberflächenstabilität zu analysieren. Die hohe kleinräumige, geochemische Variabilität (Manuskripte 1-5) kann durch den Einsatz von Verwitterungsindices und pedogenen Oxiden (Manuskript 6) je nach Maßstabsebene und zu beurteilenden Prozessen entflochten werden. Zusammen mit den dargestellten Haupteinfluss-parametern auf C- und N-Kreisläufe ist eine umfassende Beurteilung der Ökosystemfunktionen des Tibetischen Hochplateaus möglich

Threats to the Soil Resource Base of Food Security in China and Europe. A report from the Sino-EU Panel on Land and Soil

To secure adequate food supply is the major challenge for humanity in the 21st century. Growing world population and its urbanization put pressure on this basic need, which is further threatened by the constant loss of fertile land. The assessment of sustainability of food supply under increasing pressure on land resources has been selected as one of the most important priority topics of the activities of Sino-EU Panel on Land and Soil (SEPLS). The Panel has performed a number of related researches and discussed the results on a scientific seminar in January 2012 in Nanjing, China. This report is an output of this seminar with a summary of the structured discussions on the below issues. 1. Urban and peri-urban development (soil sealing and loss of land functions) Urbanization and the linked spread of infrastructural development mean sealing of soil surfaces. Soil sealing is the most rapidly growing limitation for soil functions (including biomass production function) both in China and Europe. Soil sealing in China has been taking dramatic degree in the last two decades and the process is estimated to continue in the coming period as well. While urban and peri-urban development is looked as a necessity for social development, its negative effect on natural resources are inevitable. 2. Land degradation Despite the widely recognized importance of land degradation in the unsustainability of economic development and implementation of various policies to halt degradation (e.g. green for grain programme in China; cross-compliance measures in the EU), loss of land productivity by degradation is an ongoing process both in China and the EU. Major forms of soil degradation (erosion, desertification, landslides etc.) are similar in both regions. Assessment of the causes and consequences of soil degradation processes in relation to policy actions is highlighted among the priorities of the SEPLS. 3. Intensive agriculture and multi-function management of land resources Intensification and extensification in agriculture can be considered as the main changes in land use in rural areas in both EU and China. While agricultural intensification is one of the greatest threats to the soil and environment and then hampers the sustainable development of agriculture and food security. To meet this challenge, sustainable management of multi-functionality of land resources is undoubtedly an effective strategy, in which the EU has a good expertise. Bilateral exchange of the experience and knowledge benefits the sustainable management of land resources.JRC.H.5-Land Resources Managemen

Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration

This work was funded by National Basic Research Program of China (2014CB953800), Young Talents Projects of the Institute of Urban Environment, Chinese Academy of Sciences (IUEMS201402), National Natural Science Foundation of China (41471190, 41301237, 71704171), China Postdoctoral Science Foundation (2014T70144) and Discovery Early Career Researcher Award of the Australian Research Council (DE170100423). The work contributes to the UK-China Virtual Joint Centres on Nitrogen “N-Circle” and “CINAg” funded by the Newton Fund via UK BBSRC/NERC (grants BB/N013484/1 and BB/N013468/1, respectively).Peer reviewedPostprintPostprin

Impacts of Global Change and Soil Properties on Phosphorus Transformation and Plant Responses in Alpine Grassland Ecosystem on the Northeastern Tibetan Plateau

The grassland ecosystems of the Tibetan Plateau have witnessed substantial transformations in recent decades, driven by various global factors, including alterations in temperature and precipitation, nitrogen (N) deposition, and regional effects. Despite documented shifts in species richness and distribution towards higher elevations, there is a scarcity of comprehensive plant and soil data along elevation gradients in alpine grasslands. The intricate interplay between soil properties and nutrient supply on vegetation patterns at high altitudes, particularly the response of the "grass-line" to global warming, remains unexplored. To bridge these knowledge gaps, our research investigated the impacts of global changes, specifically warming and N deposition, and soil properties on soil phosphorus (P) transformation and plant P uptake. Leveraging insights from long-term nutrient addition experiments, random sampling, and open-top chamber experiments along elevation gradients in an alpine grassland on the northeastern Tibetan Plateau, the study delved into soil properties such as texture, bulk density, soil organic carbon (SOC), and soil P fractions. Furthermore, it explores plant and microbial P pools, P acquisition strategies, and biomass. Results revealed that N input had a discernible effect on plant P requirements, particularly under conditions of deficient soil available P. Changes in P acquisition strategies wielded a more substantial influence on community structure and composition than alterations in root traits. The addition of P significantly impacted plant growth, signifying a shift from nitrogen to P limitation with increased N input. Soil properties exhibited variations among sites, but pH remained stable at 0–10 cm soil depth due to the adequate levels of calcium and magnesium in the soil, which could buffer the impact of N deposition on soil acidification in the grassland ecosystem. Strong positive correlations were observed between organic P pools, SOC, and total N, highlighting the pivotal role of soil organic matter in sustaining soil P reserves. More importantly, P limitation did not emerge as the primary factor propelling grasses to higher elevations; instead, other soil properties and nutrients might play a key role. These findings underscore the importance of specific combinations of soil properties in constraining plant growth on the northeastern plateau, thereby influencing biodiversity and biomass production. This research highlights the factors influencing effective soil nutrients and provides valuable insights into predicting the impact of global changes on the stability and productivity of alpine grassland ecosystems

Global assessment of sand and dust storms

The specific objectives of the assessment are to: 1) Synthesise and highlight the environmental and socio-economic causes and impacts of SDS, as well as available technical measures for their mitigation, at the local, regional and global levels; 2) Show how the mitigation of SDS can yield multiple sustainable development benefits; 3) Synthesize information on current policy responses for mitigating SDS and 4) Present options for an improved strategy for mitigating SDS at the local, regional and global levels, building on existing institutions and agreements