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As Central Asia is a region with wide spread water scarcity as a result of excessive irrigation of agriculture, land use changes deserve research about potential impacts on the already strained water resources. Poplars have a long tradition as agroforestry tree across Central Asia, while paulownia is new to the region, but has been gaining extreme attention as a potential plantation and/or agroforestry tree. Therefore, the water productivity of those two tree species is investigated here on 3-year-old trees, in order to provide insights in how far the newly introduced Paulownia could put additional strain on water resources compared to paulownia. Poplar (P. deltoides × nigra) increased the stem biomass by 5.4 kg at an average water consumption of 4.18 l/d (water productivity 6.79 g/l). Paulownia’s (Paulownia tomentosa × fortunei) stem biomass grew by 4.81 kg at 2.36 l/d in average (water productivity 11.9 g/l). Expanding paulownia would not exert more pressure on Central Asia’s water resources than an expansion of poplar.

Soil salinization and sodification are common processes that particularly characterize drylands. These processes can be attributed either to natural conditions or anthropogenic activities. While natural causes include factors such as climate, lithology, topography, and pedology, human causes are mostly related to agricultural land-use, and specifically, to irrigated agriculture. The objective of this study was to thoroughly review this topic, while highlighting the major challenges and related opportunities. Over time, the extent of saline, sodic, and saline-sodic croplands has increased, resulting in accelerated land degradation and desertification, decreased agricultural productivity, and consequently jeopardizing environmental and food security. Mapping and monitoring saline soils is an important management tool, aimed at determining the extent and severity of salinization processes. Recent developments in advanced remote sensing methods have improved the efficacy of mapping and monitoring saline soils. Knowledge on prevention, mitigation, and recovery of soil salinity and sodicity has substantially grown over time. This knowledge includes advanced measures for salt flushing and leaching, water-saving irrigation technologies, precision fertilizer systems, chemical restoration, organic and microbial remediation, and phytoremediation of affected lands. Of a particular interest is the development of forestry-related means, with afforestation, reforestation, agroforestry, and silvopasture practices for the recovery of salt-affected soils. The forecasted expansion of drylands and aggravated drying of existing drylands due to climatic change emphasize the importance of this topic.

After a catastrophic decline in the water level at the end of the 20th century, the formation of a new delta of the river Syrdarya has begun. The modern delta of the river is located within the Kazalinsk and Aral regions in Kyzylorda oblast. This paper gives an assessment of the hydroecological state of the river’s delta. The hydrological and ecological characteristics of the Syrdarya delta were evaluated using the data from the Karateren and Kazalinsk gauging stations. A number of hydroecological indicators are given, such as: water level, annual flow, delta area, mineralization, content of suspended substances, copper and biochemical oxygen consumption (BOС5) in the river. All indicators were compared to the maximum permissible concentration (MPC).

Central Asia is largely dominated by drylands; so agriculture depends on irrigation in most parts of the region, which results in large scale water withdrawal, mainly from rivers, and, consequently, water scarcity. Climate change is expected to aggravate such water shortages as river flows are predicted to be substantially reduced during the second half of this century, which will put additional strain on irrigated agriculture. Tree wind breaks are one option to reduce water consumption in irrigated agriculture, add to farm income, and are therefore prioritized by government policies. Still, many farmers fear that tree wind breaks may compromise crop yields and income. Therefore, based on preceding studies this paper investigates the water productivity – net present value by unit of water consumed – of tree wind break systems of single row tree rows combined with cotton (Gossypium hirsutum L.), corn (Zea mays L.), and rice (Oryza sativa L.) compared with those crops under open field conditions. The tree wind break systems attained higher water productivities across all crops, different discount rates, tree ages of tree wind breaks, and varying crop yields. Tree wind break systems at 200 m spacing attained higher water productivities than those at 1000 m spacing. In conclusion, tree wind breaks can be inserted into the irrigated agriculture as an additional source of farm income, source for wood resources, and help reducing overall water consumption in irrigated agriculture. Simple tree lines are put forward, as multiple tree rows have been shown not to attain financial gains and save less water than the single tree lines.

Common reed (Phragmites australis (Cav.) Trin. Ex Steud.) is a highly productive wetland plant and a potentially valuable source of renewable biomass worldwide. There is more than 10 million ha of reed area globally, distributed mainly across Eurasia followed by America and Africa. The literature analysis in this paper revealed that Kazakhstan alone harbored ca. 1,600,000–3,000,000 ha of reed area, mostly distributed in the deltas and along the rivers of the country. Herein, we explored the total reed biomass stock of 17 million t year−1 which is potentially available for harvesting in the context of wise use of wetlands. The aim of this paper is to reveal the distribution of reed resource potential in wetland areas of 13 provinces of Kazakhstan and the prospects for its sustainable utilization. Reed can be used as feedstock as an energy source for the production of pellets and biofuels, as lignocellulosic biomass for the production of high strength fibers for novel construction and packaging materials, and innovative polymers for lightweight engineering plastics and adhesive coatings. Thereby, it is unlikely that reed competes for land that otherwise is used for food production.

Agriculture in Central Asia largely relies on irrigation. The water is withdrawn from the rivers of the region, which predominantly originate from snowfields and glaciers. Due to global warming, these water resources are expected to decline substantially, resulting in an aggravation of already existing water scarcity. Tree shelterbelt systems, as the most prominent practice of agroforestry in Central Asia, are reported to help to reduce water consumption in irrigated agriculture. Populus. alba is one of the most important shelterbelt trees in Central Asia. Though, studies about water consumption of shelterbelts are lacking. Therefore, the objectives of this study are to (1) investigate water consumption of Populus alba trees in a shelterbelt system in Central Asia and (2) analyze the influence of local climatic conditions on the sap flow of such a shelterbelt. Tree water consumption was assessed through sap flow measurements on three trees in a crop shelterbelt system in the Chui Valley in South Eastern Kazakhstan during June and July 2016. The average daily water consumption was 187.6 l/d, 44.8 l/d, and 160 l/d for the trees, respectively. These results were extrapolated for a representative shelterbelt section. Water consumption of that section was 7.8 mm/d, while average ETo was 5.3 mm/d. Considerable influences of water vapor saturation deficit, air temperature and relative humidity on the sap flow could be observed. Solar radiation played a role, too, whereas little or no influence of wind speed on tree water consumption was found.

In the steppes, semi-deserts, and deserts of Central Asia the most productive ecosystems are riparian ecosystems like forests and shrublands. Rivers also serve as the water source for irrigation so that the major settlements and oases of the region are located near those rivers. Natural ecosystems and irrigated agriculture compete for space and water along those rivers. Expansion of irrigated agriculture resulted in water shortages along the rivers of Central Asia and degradation of natural ecosystems. The Tarim Basin, in Xinjiang, China, which covers an area of 1.02 million km², is home to a population of about 9.5 million people, and has turned into the world’s most important cotton production region with a total annual cotton lint production of 2.1 million tonnes, i.e. 8.85% of the world production, in 2010. The Tarim Basin also harbours 54% (352,200 ha) of the world’s riparian Populus euphratica Oliv. forests. The objective of this paper is to determine the actual evapotranspiration (ETa) of cotton as major crop and of the natural vegetation along the Tarim River. Among the natural vegetation, the focus is on Populus euphratica forests and Tamarix dominated shrub vegetation as the major natural ecosystems. The actual evapotranspiration was determined with the Bowen Ratio approach. Reference evapotranspiration (ETo) and crop coefficients (Kc) were calculated using the Penman-Monteith-approach. The summed ETo of the three sites investigated was from 1122 mm to 1280 mm for the growing season. The ETa sums of cotton, Populus euphratica forest, and Tamarix shrub vegetation were 489 mm, 879 mm, and 410 mm, respectively. Kc of cotton ranged between 0.30 and 0.62, thus much lower than in the FAO guidelines. This can be explained by improved varieties, drip irrigation, and plastic mulch.

Agriculture significantly contributes to greenhouse gas emissions and thus to climate change, directly through farm operations and indirectly through the energy needed to produce input materials, most prominently fertiliser, as well as through nitrous oxide (N2O) emissions from soils. Agriculture is the largest consumer of phosphorus, which is a non-renewable resource. Cotton accounts for one third of all natural and synthetic fibres of the total textile production. Today, Xinjiang, China, has become one of the most important cotton producers with highest yields worldwide. The aim of this study was to calculate the carbon (climate footprint and energy footprint) and phosphorus footprint of this high yielding cotton production and compare it to a theoretical production of an alternative fibre from Apocynum (local name: Kendyr or Kutra), which is a bast fibre plant native in Xinjiang and Central Asia. The data of the cotton production was collected through farm interviews during six years in Xinjiang. The data for Apocynum was compiled by literature from field experiments in the former Soviet Union. Cotton fibres, mainly due to high fertiliser inputs, caused a climate footprint of 4.43 kg CO2e/kg fibre, an energy footprint of 30.90 MJ/kg fibre, and a phosphorus footprint of 101 g P/kg fibre. The footprints of Apocynum are significantly lower with a climate footprint of 1.93 kg CO2e/kg fibre, an energy footprint of 21.85 MJ/kg fibre, and a phosphorus footprint of 1.6 g P/kg fibre. In cotton production, 63.9% of the climate footprint and 68.4% of the energy footprint are attributed to fertiliser production. Soil emissions of N2O account for another 22.2% of the climate footprint of cotton. The biggest potential to reduce carbon and phosphorus footprints of cotton production lie in reduced fertiliser application and re-use of plant residues. In the case of Apocynum, 65.1% of the climate footprint and 64.1% of the energy footprint are attributed to chemical treatment of the fibres in the extraction process.

Across Central Asia, agriculture largely depends on irrigation due to arid and semi-arid climatic conditions. Water is abstracted from rivers, which are largely fed by glacier melt. In the course of climate change, glaciers melt down so that a reduced glacier volume and reduced water runoffs are expected being available for irrigation. Tree wind breaks are one option to reduce water consumption in irrigated agriculture and build resilience against climate change. This paper therefore assessed water consumption of major crops (cotton, wheat, corn, rice, potato, and barley) in Kyrgyzstan and adjacent areas in combination with tree wind breaks. Crop water consumption was assessed through the Penman Monteith approach. Tree wind break types investigated were single rows from poplars and multiple rows with undergrowth by elm and poplar, respectively. Tree water consumption was determined through sapflow measurements. Seasonal ETo for field crops was 876 mm to 995 mm without wind breaks and dropped to less than half through multiple row wind breaks with undergrowth (50 m spacing). Tree water consumption was 1125 mm to 1558 mm for poplar and 435 mm for elm. Among the wind break crop systems, elm wind breaks resulted in highest reductions of water consumption, followed by single row poplars, at spacing of 50 m and 100 m, respectively. Yet, elm grows much slower than poplar so that poplars might be more attractive for farmers. Furthermore, single row wind breaks might by much easier to be integrated into the agrarian landscape, as they consume less space.

Water is a scarce resource in Central Asia, and many catchments span international boundaries, among them that of the Ili River, which is shared by China and Kazakhstan. Since 1970, the natural hydrological regime of the Ili River, both absolute flow rates and cycles, has changed due to construction of reservoirs such as that at Kapchagai, as well as natural climatic cycles and the growth of water consumption in the basin. Using data from Kazhydromet, we calculated that flow rates below Kapchagai dam averaged 468 m3/sec before construction of the dam, 366 m3/sec while the reservoir was being filled, and 489 m3/sec between 1988 and 2013. The dam has profoundly altered the annual cycle of flows in the river, with reductions in the summer and increases in the winter, when water is released to produce hydropower. The effects of these changes are being heightened by China’s increasing diversion of the river’s water. The sustainable use of decreasing water resources to conserve the biodiversity of the Ili-Balkhash basin’s ecosystems mandates a solution to the water allocation challenge between China and Kazakhstan. This will require a basin-wide approach that includes modernization of water distribution systems and careful consideration to relative priority needs for food, hydropower, and communal uses in both countries.

River deltas provide the most productive pastures in Central Asia. Simultaneously they are highly vulnerable to water inflow changes. The aim of this study was to conduct an economic assessment of the short- and medium-term effect of reduced water inflow on farmers&rsquo, performance within the Ili Delta. Primary data were collected through 35 interviews with farmers and additional experts in 2015. Production parameters for three types of individual farms were estimated and entered into a full cost accounting. Contribution margins were calculated for three scenarios: (I) sufficient water inflow (normal situation), (II) decreasing water inflow, and (III) significantly reduced water inflow (worst case). Farmers purchase hay to adapt to pasture production loss due to decreasing water inflow. This more than doubled the variable costs of worst case in comparison to normal situation for small-, medium-, and large-scale type of individual farm. Monte Carlo simulation indicates a risk of 74% (small-scale farm) and 3% (medium-scale farm) that already variable costs will exceed revenues. Despite their high fixed costs, only large-scale individual farms generate positive net farm income from operations in the worst case due to government payments from participation in elite bull program that account for one-third of total revenue.

Following the desiccation of the Aral Sea, Lake Balkhash has become the largest lake of Central Asia with an area of 17,000 km 2 . 70%–80% of the annual inflow into Lake Balkhash is delivered by the Ile River. The Ile Delta, 8000 km 2 large, is the largest natural delta and wetland complex of Central Asia and therefore is of crucial significance for the biodiversity of that region. In this paper, we reviewed the literature available with regard to vegetation, fauna, and biodiversity of the Ile River Delta and South Lake Balkhash Ramsar Site , in order to identify threats and research gaps. Threats are reduced runoff of the Ile River due to increasing water consumption upstream, overfishing, fires ignited by local people, logging for fuel wood collection, over-grazing, and water pollution from upstream. Major research gaps to be addressed are: 1) impact of reduced discharges of the Ile River on the wetland ecosystems and associated changes in livestock grazing, 2) impact of reduced discharges on spawning grounds for fish, 3) upper harvest limits for the fishery, and 4) regrowth of riparian woodlands.

A significant part of the world's largest river basins are located in areas of arid and semi-arid climate, such as the Amu Darya, Jordan, Murray-Darling, Yellow River, and Aksu-Tarim river basin. These river basins are experiencing water scarcity resulting in conflicts between upstream and downstream, conflicts between water users, and degradation of the natural ecosystems. Therefore, in many river basins, including the Aksu-Tarim river basin, water quota systems have been established, in order to allocate water under scarcity. The Aksu-Tarim river basin (NW China) has developed into one of the most important cotton production areas worldwide. In this paper, we aim at assessing the water consumption through irrigated agriculture, mainly cotton, and natural vegetation in the Aksu-Tarim river basin against the background of this water quota system. Firstly, we map the evapotranspiration (ETa) as water consumption of irrigated agriculture and natural vegetation in the Aksu-Tarim river basin. Secondly, we calculate water balances and relate them to the water quota system. We employed the remote sensing method Simplified Surface Energy Balance Index (S-SEBI), in order to map ETa based on MODIS satellite images for the growing seasons 2009, 2010, and 2011. Thereby, the MODIS products 8-day land surface temperature (MOD11A2), 16-day albedo (MCD43A3), and 16-day NDVI (MOD13A1) were used. The ETa of cotton ranges from 884 to 1198 mm. The ETa of the natural vegetation of a total coverage ranges from 715 in 2009 to 960 mm in 2011, clearly following the annual runoff of the Aksu and Tarim River. The water balance of the Aksu-Tarim river basin is −3.25 to −3.73 km3, 0.1–0.53 km3, and −3.55 to −4.12 km3 in 2009, 2010, and 2011, respectively. The water quotas along the Aksu River and the upper reaches of the Tarim are exceeded by water consumption, while the quotas along the middle and lower reaches are not met. Considerable amounts of groundwater, including fossil groundwater, are exploited for irrigation along the Aksu and Tarim River, which must be regarded as exploitation of a non-renewable resource.

In Central Asia, agriculture, notably irrigated agriculture, is the largest water consumer. Currently, flood and furrow irrigation are the dominant irrigation methods in Central Asia, in particular in the post-Soviet countries. Against the background of current and increasing competition for water—e.g., through reduced river runoffs in the course of climate change—water consumption of agriculture needs to be reduced. On the field plot level, improved irrigation technologies, like drip irrigation or plastic mulch, can reduce water consumption substantially. Alternatively, tree lines as wind breaks (shelterbelts) also can reduce crop water consumption, as shown by research from many drylands around the world. As previous research has concentrated on crop water consumption and not on tree water consumption, this paper brings the two together, in order to approach a more holistic picture, in how far shelterbelt systems, including the trees, may have the potential to save water or not. Crop water consumption was assessed through the Penman–Monteith approach for corn, wheat, potato, barley, and pear under open field conditions and under an assumed influence of a tree shelterbelt. Tree water consumption was investigated through sap flow measurements. Crop water consumption was reduced by 10–12% under influence of a shelterbelt compared to open field conditions. When water consumption of shelterbelts was added, a slight reduction of water consumption of the whole crop-shelterbelt system was found for corn, potato, and pear under the assumption 25 ha (500 × 500 m) field sizes. Under an assumption of 4 ha (200 × 200 m) field size, water consumption of the whole crop-shelterbelt system was higher for all crops investigated except for pear. The results suggest that shelterbelts may play a role in improving water resource management in Central Asia in the context of water demanding crops, like corn or cotton. In further research, other effects of shelterbelts, like increased crop yields and additional income from trees, need to be investigated.

The Ili River is a transboundary river shared by China, upstream, and Kazakhstan, downstream. The Ili is the main water supplier to Lake Balkhash, the largest lake in Central Asia after desiccation of the Aral Sea. Agreements over water allocation have not been concluded between China and Kazakhstan. This paper investigated water consumption of agriculture and riparian ecosystems in the Ili river basin, to provide information for further debate on water allocation, through the Simplified Surface Energy Balance Index (S-SEBI) approach using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images. The overall water consumption in the Ili river basin was 14.3 km3/a in 2000, 17.2 km3/a in 2005, and 15 km3/a in 2014. In 2000, China and Kazakhstan consumed 38% and 62% of the water, respectively. By 2014, the relative share of China’s water consumption increased to 43%. In China, 80% of the water consumption is due to agriculture. High runoff during the past 10 years enabled increasing water consumption in China and sufficient water supply to agriculture and riparian ecosystems in Kazakhstan. When runoff of the Ili River decreases, as expected for most rivers in Central Asia, then irrigation efficiency has to be further increased in China, and irrigation systems in Kazakhstan have to be restored and modernized in order to reduce water consumption and protect Lake Balkhash and the riparian ecosystems.

Wuliangsuhai Lake is one of the largest wetlands in Inner Mongolia, China, half covered by large and highly productive Common Reed (Phragmites australis) stands. However, benefits from current utilization practices do not cover the costs of harvesting. Against this background, Wuliangsuhai Lake is taken as a case study for the assessment of the potential use of reed biomass for energy production. Taking into account, both the present and the potential reed availability, four scenarios are considered, i.e. (1) a decentralized application in household stoves, (2) a centralized reed supplied combined heat and power gasification, (3) a direct combustion plant and (4) a co-firing in existing coal plants. Two field campaigns have been conducted firstly collect information about the current situation of the reed and coal market and secondly to measure reed above-ground biomass. The suitability of reed for thermochemical conversion processes has been evaluated by means of chemical-physical, calorimetric, and thermal analyses of the samples. The potential energy production is valued regarding the profitability on the current Chinese energy market. Possible subsidies for reed as a renewable resource are taken into account. The evaluation has shown that reed has the potential to act as an energy feedstock. In relation to the considered study site, reed energy use can be profitable on the household level, in CHP combustion plants and in co-combustion. Gasification CHP plants are not economic feasible under current conditions. The results show that reed can be a sustainable alternative to highly health and environment damaging coal.

To implement effective water resource management strategies, a sufficient data basis about the hydrologic situation must be available. An important parameter is the water consumption by the natural environment, e.g., evapotranspiration (ET). This study delivers actual evapotranspiration rates (ETa) computed on the basis of Landsat TM/ETM+ and MODIS data. Vegetation mappings recorded during a field work campaign in 2012 allowed the correlation of ET rates to certain units of vegetation. The study site is located in the Heihe river basin, Northwest China, where the landscape is characterized by extending land under cultivation along the middle reaches and ecologically valuable Tugai vegetation further downwards. Due to the arid climate, all agriculture depends on irrigation with water taken from the Heihe River. As a result of a massive expansion of irrigated land in the last decades, an imbalance with regard to water allocation has developed. It is characterized by an overexploitation of the water resources in the middle reaches and a strong degeneration of the natural Tugai vegetation along the lower reaches due to water shortage. As a response, a water distribution plan has been adopted to define target amounts of water that shall reach the lower parts of the river. Total values of the ETa over the whole vegetation period for corn, dates, orchards and grapes amount to 667.7, 762.2, 703.5 and 483.9 mm, respectively. For forest vegetation (ground coverage 80 %) and for shrub vegetation (80–100 % ground coverage), values of 496–530 mm and 177–233 mm were calculated, respectively. Areas with lower ground coverage show significantly lower ETa values. Spatially, ETa values decrease from the center towards the border of the oasis and from the middle towards the lower reaches. Agricultural land presents the largest water consumer. The total ETa values over the vegetation period amount to 2.15 km3 (middle reaches) and 0.28 km3 (lower reaches), respectively. On this basis, a minimum discharge of 0.34 km3 was calculated to maintain the natural vegetation downstream.

Many river basins in the arid and semi-arid parts of the world are experiencing water scarcity due to water consumption by agriculture resulting in conflicts between upstream and downstream, conflicts between water users, and degradation of the natural ecosystems. The Tarim Basin, Xinjiang, China, has developed into the world’s most important cotton production region with 8.85% of the world’s production. Under the extremely arid climate with annual precipitation of below 100 mm, the water consumption due to irrigation resulted in water scarcity and conflicts between water users as well as between upstream and downstream. The Tarim river catchment harbors about half of the world’s Populus euphratica riparian forests, which are impacted by water shortage. Starting in the 1990s, a unified water management system with a quota system for water distribution has been set up. We introduce this unified water management system and analyze how the water distribution works in practice. Ecologists and forestry officials claim more water for environmental flow, whereas water management officials give priority to agricultural, industrial, and domestic water use. The water quotas for downstream regions are frequently not fulfilled, especially during the non-flood season in spring and early summer posing a risk to water users. Water users with financial and political advantages gain more water security than others. The water quotas are annual quotas. These quotas should be differentiated into seasonal quotas, in order to enhance water security for the downstream section of the Tarim all year round.

Across Central Asia, agriculture largely depends on irrigation due to arid and semi-arid climatic conditions. Water is abstracted from rivers, which are largely fed by glacier melt. In the course of climate change, glaciers melt down so that a reduced glacier volume and reduced water runoffs are expected to be available for irrigation. Tree wind breaks are one option to reduce water consumption in irrigated agriculture and build resilience against climate change. This paper therefore assesses the water consumption of major crops in Kyrgyzstan and adjacent areas, i.e., cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.), corn (Zea mays L.), rice (Oryza sativa L.), potato (Solanum tuberosum L.), and barley (Hordeum vulgare L.) in combination with tree wind breaks. Crop water consumption was assessed through the Penman Monteith approach. Tree wind break types investigated were single rows from poplars (Populus spec.) and multiple rows with understory vegetation by elm (Ulmus minor L.) and poplar, respectively. Tree water consumption was determined through sapflow measurements. The seasonal reference evapotranspiration (ETo) for field crops was 876&ndash, 995 mm without wind breaks and dropped to less than half through multiple row wind breaks with understory vegetation (50 m spacing). Tree water consumption was 1125&ndash, 1558 mm for poplar and 435 mm for elm. Among the wind break crop systems, elm wind breaks resulted in the highest reductions of water consumption, followed by single row poplars, at spacing of 50 and 100 m, respectively. However, elm grows much slower than poplar, so poplars might be more attractive for farmers. Furthermore, single row wind breaks might by much easier to be integrated into the agrarian landscape as they consume less space.

Deserts belong to the least productive terrestrial ecosystems, but along rivers, they may exhibit a high productivity. In central Asia, Populus euphratica Oliv. is the dominant tree species of the riparian ‘Tugai’ vegetation. In terms of climate change mitigation, ‘Tugai’ restoration may be traded for on the international carbon market. However, detailed knowledge of ‘Tugai’ productivity is lacking. Within this study, we modelled the productivity ofP.euphratica based on tree-ring data (r 2 ¼ 0.73,P ,, 0.001) and applied the derived model to estimate the stand productivity of this species within the Kabakly nature reserve on the Amu River, Turkmenistan. Productivity estimates ranged from 0.3 to 3.0 t ha 21 year 21 and expressed the same magnitude as the data mentioned previously in the literature. Forest productivity appeared to be negatively correlated with distance from the river, which was consistent with Quickbird remote sensing data. Quickbird net differenced vegetation index (NDVI) was strongly correlated with Landsat NDVI (r ¼ 0.91,P , 0.001), indicating the general potential to upscale net primary productivity estimates forP.euphratica. Tree ring series expressed no synchrony, for which possible explanations are discussed. Under ideal conditions P. euphratica sequesters CO2 and thus may be considered a suitable tree species for carbon trade mechanisms and climate change mitigation.

Carbon stocks and carbon accumulation in the earth's drylands have gained increasing attention. The winter-cold deserts of Middle Asia, i.e. in Kazakhstan, Uzbekistan, and Turkmenistan, cover an area of 2.5 million km2. Within these deserts, the two Saxaul species White Saxaul (Haloxylon persicum Bunge ex Boiss. & Buhse) and Black Saxaul (Haloxylon aphyllum (Minkw.) Iljin) are dominant woody species with a potential distribution area of about 500,000 km2. From the 1950s until today, the Saxaul vegetation has been degraded through logging and over-grazing. In this paper, we estimate the current and potential living above ground and below ground biomass of the Saxaul vegetation and its carbon stock. The living above ground biomass ranges between 1.5 t/ha and 3 t/ha. The potential carbon stocks above ground and below ground amount to 29.4–52.1 million t and 22–81.4 million t, respectively. Today, only 11%–28% of the potential biomass and carbon stock have remained. The carbon stock of the Saxaul vegetation is low compared to other ecosystems of the earth, but restoration and conservation of Saxaul vegetation is one way to sequester carbon through vegetation for Uzbekistan and Turkmenistan, which do not have much other woody vegetation.

Summary In the Central Asian deserts, the floodplains along the large river systems like the Amu Darya, Syr Darya and Tarim harbour the highest biodiversity and provide a wide range of ecosystem services for men in those regions. Against the background of the potential use of wood biomass and carbon sequestration, we investigate the biomass of floodplain forest (Tugai) ecosystems along the Tarim River, north-west China, and the Amu Darya, Turkmenistan. These forests are dominated by Populus euphratica Oliv. Under very good water supply conditions, the stand biomass, comprising aboveand below-ground components of P. euphratica, was 58.4 t ha 21 , corresponding with the highest tree densities. The stand biomass of P. euphratica under non-optimal conditions, i.e. prolonged flooding or periods of drought with sinking groundwater levels, ranged from 16 to 28 t ha 21 . The observed stand biomass values for P. euphratica are in the range of values found by others in Xinjiang and Inner Mongolia, China, but lower than the biomass of temperate forests. However, among the desert, semi-desert and steppe ecosystems, the riparian P. euphratica forest is the ecosystem with the highest above-ground biomass. Thus, the riparian forests in Central Asia contain a regionally remarkable amount of biomass.

Summary Tugai forests are the riparian forests along the rivers in the continental desert regions of Central Asia, i.e. the Tarim River, Amu Darya and Syr Darya. They mainly consist of Populus euphratica Oliv., Populus pruinosa Schrenk. and Elaeagnus oxycarpa Schltdl. As a consequence of land opening campaigns, large areas of Tugai forests were destroyed after the 1950s. Due to excessive use of water for irrigation, the remaining Tugai forests are under severe threat. Near natural Tugai forests still exist along the Tarim middle reaches in the Tarim Huyanglin Nature Reserve, Xinjiang, NW China. There is a gap in understanding, how the seedlings of P. euphratica establish as trees which continuously connect to the groundwater. Therefore, the set of conditions which must be met for germination and successful establishment, i.e. formation of Tugai forests, was investigated along a representative transect still under natural conditions. P. euphratica seedlings germinate in belts during the retreat of the summer fl ood on freshly deposited sites bare of other vegetation. Such germination sites are formed by river dynamics. While germination takes place regularly in the study area, successful establishment is restricted to few germination events. Seedlings face dropping groundwater levels during spring and early summer of the second year after germination. Therefore, for successful establishment, it is essential that the fl ood of the second year starts in time and is high enough, in order to replenish the groundwater. Furthermore, clayey soil layers in the subsoil may play a role for successful establishment, too, as they store water better than sandy soil layers.

The Tarim River is the major water source for all kinds of human activities and for the natural ecosystems in the Tarim Basin, Xinjiang, China. The major water consumer is irrigation agriculture, mainly cotton. As the area under irrigation has been increasing ever since the 1950s, the lower and middle reaches of the Tarim are suffering from a water shortage. Within the framework of the Water Law and two World Bank projects, the Tarim River Basin Water Resource Commission was founded in 1997 in order to foster integrated water resource management along the Tarim River. Water quotas were fixed for the water utilization along the upstream and downstream river stretches. Furthermore, along each river stretch, quotas were set for water withdrawal by agriculture and industry and the amount of water to remain for the natural ecosystems (environmental flow). Furthermore, huge investments were undertaken in order to increase irrigation effectiveness and restore the lower reaches of the Tarim River. Still, a regular water supply for water consumers along the Tarim River cannot be ensured. This paper thus introduces the hydrology of the Tarim River and its impacts on land use and natural ecosystems along its banks. The water administration in the Tarim Basin and the water allocation plan are elaborated upon, and the current water supply situation is discussed. Finally, the adaptations made due to issues of water allocation and water scarcity on the farm level are investigated and discussed.

In recent decades, the restoration of degraded and damaged ecosystems has become a challenge for landscape management, nature conservation, and sustainable land-use development throughout the world. As rivers and their floodplains provide many ecosystem services, e.g. the purification of water, combating desertification, the accumulation of carbon, and providing habitats for plants and animals, a particular focus is on their restoration. As a case study, we focus on the Tarim River and its floodplain in continental-arid Southern Xinjiang, NW China, and aim at an interdisciplinary approach to the landscape, taking ecological as well as socio-economic aspects and cultural history into account. Therefore, we describe the natural environment, as well as outline the historical development and the cultural and economic background. Key species of the floodplain ecosystem, such as Populus euphratica, Phragmites australis, Tamarix sp. and Apocynum venetum are particularly taken into account as part of the natural environment, as well as being important species providing ecosystem services and sustainable land-use perspectives. On the basis of our own investigations, we develop a future strategy for the sustainable development of the Tarim river floodplain.

In Central Asia soil salinization is a wide-spread concern. Biomass harvested from the moderate salt-tolerant species Haloxylon aphyllum and Apocynum pictum can be used as fodder as well as for textile fibers and medicinal purposes, respectively. These plants offer opportunities to generate income from saline soils.