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Tree wind break systems are found in many parts of the world. In particular in windy and arid regions they help to increase crop yields and reduce crop water consumption. Due to these reasons, tree wind breaks have a long tradition in Central Asia and were strongly propagated there during Soviet Union times. After the Soviet Union had disintegrated and the countries in Central Asia had become independent, energy supplies from Russia ceased and fuel wood became the primary energy source for large parts of the population, in particular rural population. Consequently, most of those tree wind breaks were cut down for fuel wood during the 1990s. Now, governments wish to restore these systems, but many farmers are skeptical about the economic returns from investment in tree wind breaks. Against this background, this study calculated revenues, costs, and profits for tree wind break systems of poplars combined with wheat, barley, corn, alfalfa, cotton, and rice in Kyrgyzstan, based on interviews and field observations. Tree wind breaks with more than one row of trees (multiple row type) did not result in financial gains for most crop tree wind break systems compared to open field conditions, while single tree wind breaks were cost-neutral or resulted in small economic gains, also under different discount rates and revenues attained from crops and trees. Among the different grid sizes, the 200 m × 200 m grid attained the highest financial surplus compared with open field conditions and other grid sizes. Thereby, effectively it is recommended to establish tree wind breaks along existing field borders or irrigation ditches while keeping an average distance between tree lines of 200 m, in order not to impede farm operations.

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.

Anthropogenic activities and climate change contribute to the deterioration of wetlands worldwide with Central Asia (CA) being among the regions which are most severely affected. This study examined how the distribution of wetlands in CA has changed in the last two decades. Emphasis was put on inland wetlands protected as International Bird and Biodiversity Areas. Time series of maps of wetlands (i.e. reed beds) were created for the years 2000, 2005, 2010, 2015 and 2018. A supervised classification approach was applied using NDVI of MODIS satellite images with 1000m resolution for the respective years. Ground control points were acquired through fieldtrips to the lower Chu River, upper Ili River and Ili River Delta in Kazakhstan and the Amu Darya River Delta and the Lower Amu Darya State Biosphere Reserve in Uzbekistan. The applied method is not applicable for the classification of wetlands in northern Kazakhstan. The vegetation there is too alike to the wetland vegetation in terms of values and seasonality of NDVI. For the remaining part of the study area, the applied method delivers satisfying results. However, it is difficult to determine a general trend for most wetland areas since there is a large variability between years. This study marks a first attempt at examining wetlands in CA at a regional scale. The results provide a baseline for further, more detailed research through either fieldtrips or by using higher resolution remote sensing data.

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).

Background: Agroforestry systems have the potential to provide timber and wood as a domestic raw material, as well as an additional source of income for rural populations. In Central Asia, tree windbreaks from mainly poplar trees have a long tradition, but were largely cut down as source for fuel wood after the disintegration of the Soviet Union. As Central Asia is a forest-poor region, restoration of tree windbreaks has the potential to provide timber and wood resources to that region. This study aimed to assess the potential of tree windbreaks to contribute to domestic timber and wood production. Methods: This study rests on a GIS-based analysis, in which tree lines (simulated by line shape files) were intersected with cropland area. The tree data to calculate timber and wood volumes stem from a dataset with 728 single trees from a relevant range of climatic conditions. Results: The potential annually available timber volumes from tree windbreaks with 500 m spacing are 2.9 million m3 for Central Asia as a whole and 1.5 million m3 for Uzbekistan alone, which is 5 times the current domestic roundwood production and imports of the country. Conclusions: tree windbreaks offer untapped potential to deliver wood resources domestically as a raw material for wood-based value chains.

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.

Research Highlights: Despite a long tradition of using poplars as wood source across Central Asia, recent international breeding developments have not penetrated that region yet. This study therefore explored growth performance of 30 local and international poplar cultivars. Background and Objectives: The Central Asian countries are forest poor countries, which need to cover the domestic wood demand through costly imports. Therefore, fast growing trees, such as poplars, are gaining increasing attention as option to grow wood domestically. The most common cultivars date back to Soviet Union times. As recent breeding developments have not reached the region, this study aims at investigate the growth performance of a number of newly developed poplar cultivars. Materials and Methods: The investigated cultivars were planted as cuttings across nine sites in Kyrgyzstan, Kazakhstan, and Tajikistan between 2018 and 2020. Results: Under warm climate conditions, i.e., low elevations, P. deltoides x nigra hybrids attained highest stem volumes and biomass yields, up to 16.9 t/ha*a after two years, followed by P. nigra xmaximoviczii hybrids. One of the P. deltoides xnigra hybrids reached a tree height of 10.5 m after three years. On higher elevations, e.g., in the Pamirs and in Naryn, P. maximoviczi x trichocarpa hybrids and P. trichocarpa cultivars grew faster than the former hybrids. Conclusions: The cultivars explored in this study should be included into plantations or agroforestry systems that are being established, provided that land users are able to thoroughly control weeds and ensure nutrient and water supply. If sufficient weed control, nutrient supply, or water supply cannot be ensured, then land users should opt for local cultivars (e.g., Mirza Terek) or the P. nigra xmaximoviczii hybrids or P. trichocarpa, in order to avoid failure.

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.

Two saxaul species - black saxaul (Haloxylon aphyllum Minkw.) and white saxaul (Haloxylon persicum Bunge) - constitute the principal arboreal cover of the cold continental deserts of Central Asia. While the latter is a rain-fed shrub distributed on sand dunes, the former is a ground-water phreatophyte mainly found on alluvial terraces. Saxaul has played an important role as a fodder plant also used as firewood by local herders. Due to over-grazing and over-exploitation for fuel during the past fifty years, the oncedominant saxaul vegetation has considerably degraded. Important growth characteristics at the present plantations (such as height, and basal trunk and crown diameters) show a direct quantitative relationship between the plants' age up to the 25-year lifetime and the total tree biomass reduced by natural degradation. Annual productivity largely depends on the overall vegetation density that reflects specific environmental conditions at particular locations. The recommended harvest rate, ...

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.

The article analyses a transdisciplinary wicked upstream-downstream conflict over water allocation in an arid region of Inner Mongolia (China). This conflict is about scarce water resources which can be either allocated to irrigation agriculture upstream or to preservation and restoration a rare ecosystem downstream. This conflict is located at the interface of environmental and agricultural ethics. The case study is about Heihe River, agricultural demands for irrigation in the region of Zhangye, and endangered Tugai forest at downstream Heihe in Ejina oasis. Authors use a theoretical approach of environmental philosophy and rely on the concept of 'strong sustainability'. From this background two normative yardsticks are derived: a constant natural capital rule and the overall satisfactory goodness of a river basin. Both yardsticks are not met at Heihe. Downstream, we see the endangered Tugai forest as a location which should be preserved de re. We argue for a viable institutional water saving strategy within the agricultural areas of Zhangye district by which Tugai forests at downstream Heihe might be restored. Our case study indicates that even wicked problems can find proper and prudent solutions.

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.

The reestablishment of agroforestry systems in Central Asia, combining crop production with protective tree shelterbelts, provides significant potential to improve farming systems. This includes increasing crop yields, additional income from timber, as well as reducing soil degradation and wind erosion. Thus, adopting shelterbelts as a form of pro-environmental behavior provides a number of socio-economic benefits, although some trade-offs need to be considered as well. This paper investigates factors that shape the perception of&mdash, and attitude towards&mdash, the establishment of tree shelterbelts by farmers in two case study regions in Kyrgyzstan. Applying a conceptual framework distinguishing between extrinsic and intrinsic factors, research methods included semi-structured interviews with farmers and local policy makers. The results show spatial differences in the perception of shelterbelts, both on the regional and on the village scale. In general, shelterbelts were negatively perceived by more than half of the farmers. The main concern raised by farmers was the shading of crops by shelterbelts, resulting in a decrease of yield. In addition, small field sizes and potential conflicts with neighbors were key concerns. Furthermore, rules set by local self-government bodies were inconsistent with the legislative framework, posing significant restrictions to the adoption of sustainable land use practices.

Lake Balkhash is the largest water body in Central Asia. More than three-quarters of its inflow comes from the Ili River, which is under increasing strain due to the diversion of water for energy and food production. Commercial fishing in Lake Balkhash began in 1929 and is currently in a state of crisis. The construction of the Balkhash dam and reservoir in the late 1960s reduced Ili River flows into the lake and upset the natural cycle of spring floods, which greatly reduced spawning and feeding areas for carp (Cyprinus carpio). Carp populations were consequently reduced by more than 90% during the filling of the reservoir and have not recovered, even though the lake’s level subsequently rose. Catches of carp and freshwater bream (Abramis brama orientalis) have shown an inverse relationship since the 1960s, and the age structure of freshwater bream is changing. Historically, most captured fish of this species were 4- to 7-years-old, but smaller, 3- to 5-year-old fish have dominated recent catches. The total fish harvest from Lake Balkhash is currently at near historical lows, not just because of environmental factors, but also because of structural changes triggered by the collapse of the Soviet Union. Poaching, government disinterest, lack of enforcement of fishing regulations, and the economic challenges faced by today’s small fishing enterprises all contribute to the problem.

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.

The city of Aksu, situated at the northern fringe of the Taklimakan Desert in northwest China, is exposed to severe periodic dust and sand storms. In 1986, local authorities decided to establish a peri-urban shelterbelt plantation, the so-called Kökyar Protection Forest, with the aim of reducing dust and sand storm impacts on Aksu City by the regulating ecosystem services provided by the plantation. It was realised as a patchwork of poplar shelterbelts and orchards. The total area of the plantation reached 3800 ha in 2005. The Kökyar Protection Forest is used as a case study to answer the following question: under which institutional frameworks and to which financial conditions can peri-urban shelterbelts be established and maintained? The endeavour of planting the shelterbelt was made possible by the annual mass mobilisation of Aksu citizens, based on the Chinese regulation of the "National Compulsory Afforestation Campaigns". Establishment costs amounted to ca. CNY 60 000 ha−1 (ca. USD 10 000 ha−1). Permanent maintenance of the plantation is facilitated by leasing orchard plots to private fruit farmers. From the perspective of the local economy, annual farming net benefits generated by Kökyar fruit farmers more than compensate for annual government grants for maintenance, resulting in an average overall monetary net benefit of at least CNY 10 500 ha−1 (ca. USD 1600 ha−1) in the long term. For a more complete understanding of Kökyar Protection Forest, future research should be directed towards quantifying the effect of its regulating ecosystem services and on investigating the negative downstream consequences of its water consumption.

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.

This study explores a paradigm of sustainable land use in the oases along the Tarim River of northwest China, where a fragile, semi-arid riparian ecosystem is being damaged by excessive land and water use for agriculture, especially for the growing of cotton. The reliance of agriculture on water-demanding cash crops in this region poses a grave threat to survival of the natural Tugai vegetation in the area and to the long-term sustainability of the region. We explored the hypothesis that the species Apocynum pictum (A. pictum), known as Lop-Kendir by locals, and the Chinese red date (Zyzyphus jujube) may act as sustainable crop substitutes for the region, thereby replacing the widely distributed cash crop of cotton that has high water demands. Therefore, we investigated current utilization and cost-revenue structure of these two alternative plants and compared the results to cotton. Three natural resource management types of A. pictum were both identified in the wild and cultivation, with cost-revenue analysis carried out for each. The results show that all three types of institutional arrangements of natural resources, which are namely open access, ranching and farming, were present in our study and at various levels for A. pictum. A. pictum farming costs 16,250.25 yuan/ha, generates 49,014.45 yuan/ha of revenue from raw materials and brings a profit of 32,764.2 yuan/ha, which is the highest of all three cash crops compared. The Chinese government encourages Chinese red date plantations with a “Grain for green” campaign in the Tarim Basin with this plant being more profitable than cotton, which could serve to diversify the region’s agriculture. We conclude that A. pictum offers opportunities for the restoration of vegetation in riparian ecosystems on salinized sites under the arid conditions of the Tarim Basin. Furthermore, it can serve as a viable land-use alternative to cotton for cash crop agriculture, as it may generate a certain income in the form of tea and fibers as well as fodder for livestock.

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.

Lakes are threatened ecosystems in drylands of Central Asia. The Wuliangsuhai Lake (“W-Lake”) is a case in point. Located in the Hetao Irrigation Area (“HIA”), W-Lake is a rare multifunctional inland lake in arid North China. It provides a wide range of ecosystem services, including provision of products, regulation of water and climate, water purification, biodiversity conservation and cultural services. The lake’s major water input is the drainage water from HIA’s farmlands. Those farmlands divert water directly from the Yellow River for irrigation. Unsustainable agricultural practice in HIA has gravely impacted on W-Lake in terms of reduced water quantity and degraded water quality. However, the linkage between agricultural practice in HIA and the environmental changes of W-Lake has been rarely investigated. Existing data focus mainly either on W-Lake or on HIA’s farmlands with overwhelmingly technical and end-of-the-pipe solutions. In view of the above, this paper develops four qualitative scenarios on HIA from social, economic and ecological perspectives. The four scenarios are: (a) green growth; (b) strong sustainability; (c) shift to swamp; and (d) worst case. The main aims of this paper are (1) to assist local decision makers of HIA in policy-making and (2) to develop concepts and strategies within the larger framework of integrated water management that shall inspire conservation efforts in other Central Asian regions.

The Amu Darya River is the major water source for Turkmenistan contributing 88 % to the total amount of surface water available to the country. Lebap Province harbours oases and natural riparian vegetation along the Amu Darya River. In the oases, cotton, wheat, and corn as well as fruit and vegetables are grown under irrigation. While cotton was strongly promoted during Soviet Union times, the wheat area was enlarged after independency of Turkmenistan, in order to secure food self-sufficiency. In the literature, a very high crop water requirement has been reported for cotton in Turkmenistan. In this paper, the objective is to investigate the consumptive water use, i.e. actual evapotranspiration, of the major crops cotton, wheat, and corn, the household plots, and the natural vegetation within Lebap Province of Turkmenistan. Actual evapotranspiration (ETa) was mapped from Landsat satellite images for the vegetation seasons 2009 and 2010. Additionally, reference ET (ETo) and crop ET (ETc) were calculated. ETa for riparian (Tugai) forests and Tamarix shrubs was 907–1,043 and 239–259 mm, respectively. ETa for the mapped crops cotton, wheat, rice, and gardens was 485–658, 156–350, 685–935, and 416–615 mm, respectively. ETo was 929 and 979 mm in 2009 and 2010, respectively. ETc for cotton and rice was 896 mm in 2009 and 925 mm in 2010 and 1,085 mm in 2009 and 1,198 mm in 2010, respectively. The low ETa values are explained partly by under-estimation through the method applied, partly by low yields of the crops. There is a big gap between the amount of water taken up from the Amu Darya and the water really consumed by the irrigated crops. This low water use efficiency might be due to water losses from channels and high amounts of water needed for soil preparation, i.e. leaching of salts.

Common reed (Phragmites australis (Cav.) Trin. ex Steud.) is a key wetland species with cosmopolitan distribution. In this study, we examined nitrogen (N) and phosphorus (P) stoichiometry in reed organs, using data of 28 samples from Wuliangsuhai Lake and 17 samples from the wetlands of the city of Zhangye, both located in northern China. Our results showed that the average N and P contents and N:P ratio of the whole plant (geometric mean of mass ± standard deviation) were 14.1 ± 5.3 mg g−1, 0.95 ± 0.54 mg g−1, and 16 ± 5, respectively. These values exhibited significant differences among the organs of reed, including the flowers, leaves, stems, roots, and rhizomes, ranging on average from 6.4 ± 4.2 (stem) to 31.4 ± 5.2 mg N g−1 (leaf), from 0.652 ± 0.647 (stem) to 2.05 ± 0.33 mg P g−1 (flower), and from 10 ± 6 (stem) to 24 ± 4 (leaf) on N:P ratio. The N content closely co-varied with P content within and across organs, and interestingly, P content was more variable than N content. The N and P contents of the whole reed plant, stems, and rhizomes were positively correlated with the availability of these nutrients in water and sediment, but were relatively stable in leaves and flowers. Structural organs probably perform a buffering function of storing N and P in plants. All such stoichiometric patterns can influence the reed bed stand structures such as stem density, stem height, and basal diameter, and may contribute to the wide distributions of reed species in various environments. Our findings are applicable to the management of reed-dominated wetlands.

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.

To investigate the influence of groundwater and river dynamics on genetic diversity and clonal growth of Populus euphratica forests along the Tarim river system (Xinjiang Prov., China), we genotyped nine old stands in three study areas of various distance to the main river. Using seven microsatellite loci, 850 genotypes were found among 1701 analyzed trees, with 204 of these comprising at least two trees. Population genetic analyses revealed a low degree of genetic differentiation (Dest = 0.014, Gst = 0.005), and no restriction to gene flow between stands. The forests can therefore be described by the infinite island model of gene flow. Stands in the three study areas differed strongly in clonality: in area I 82% of all trees grew from root suckers, clones averagely comprised 10.5 ± 2.0 trees; figures in area II were 45% and clones of 4.5 ± 1.0 trees, respectively. Area III had the largest trees, but was almost non-clonal (less than 3% of all trees were root suckers). By measuring current ground water depth and reconstructing river courses over more than one century, the varying ground water supply was identified as the most likely reason for the different degree of clonal growth. Neither survival nor lifespan of a stand depends on clonal growth. In the harsh environments inhabited by P. euphratica, the most important function of clonal growth may be the enhanced reproductive impact of large clones.

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.

Central Asia is the region with the worldwide highest number of endorheic or closed river basins. Many of those river basins are transboundary ones. Following the desiccation of the Aral Sea, Lake Balkhash has become the largest lake of Central Asia with an area of 17,000 km2. The Ili Delta, in total 8000 km2 large, is the largest natural delta and wetland complex of Central Asia. Seventy percent of the Ili River’s runoff is generated in China. So, the Ili Delta is a showcase for a wetland complex lying downstream in a transboundary river basin. The objective of this paper is to assess the area and distribution of the wetlands and Phragmites australis-dominated reed vegetation as major natural ecosystems in the Ili Delta and their associated ecosystem services. An analysis of Rapid Eye satellite images revealed that there are wetlands and reed vegetation on a total area of 211,778 ha in the Ili Delta. A total of 85,400 ha are submerged reed beds with a total estimated biomass of 869,097 t. P. australis is used as fodder and raw material. Currently, there are about 100,000 livestock grazing in the delta. The submerged reed is planned to be used by a factory for chipboards and a paper factory. The wetlands are important spawning grounds for fish of Lake Balkhash. In 2014, almost 10,000 tourists visited the delta. Most of all tourists come from Almaty, followed by Russia, other regions of Kazakhstan, and Europe (outside Russia).

The Haloxylon vegetation in Central Asia has undergone vast changes throughout the last century, which has lead to a strong degradation and desertification of the desert ecosystems in Kazakhstan, Uzbekistan, and Turkmenistan. In terms of combating desertification and restoration of ecosystems, two pilot-projects recently are aiming at the reforestation of Haloxylon ecosystems. Hereby, two of the internationally discussed climate change mitigation activities may be of higher relevance: (I) to sequester CO2 through afforestation and reforestation and (II) to substitute fossil fuels by sustainable utilization of regenerative bio-fuels. With particular focus on Central Asian desert ecosystems, the questions arose: (I) to which extent Haloxylon species – the dominant shrub species – sequester CO2, (II) what the recent carbon pool related to Haloxylon ecosystems is, and (III) in which magnitude the existing and/or reforested ecosystems could be utilized for bio-fuels sustainably. Therefore, this study aims at the derivation of allometric models including carbon contents for the two Haloxylon species in Central Asian desert ecosystems. A first application to measured transect data across Central Asia is carried out to reflect the recent biomass variability of the two study species. We found, that above- and below-ground biomass for both species is best modeled when taking growth height, basal area, and canopy area of shrubs into account (0.87

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.

Kyrgyzstan is home to one of the largest areas of natural walnut forest in the world. These forests support significant genetic diversity of many important ancestral strains of fruit and nut tree species. The walnuts from those forests are a major source of cash income for many households in that region. Most of the walnut forests are overgrazed, which effectively hinders natural rejuvenation. This has resulted in overaged and degraded forests. Currently, tree cutting for timber is forbidden under a moratorium. In some instances, walnut trees grow in agroforestry systems together with potato and corn as annual crops or apples and berries, alongside hay. Reforestation and afforestation in the walnut forest region is imperative to secure walnut harvests and associated incomes once the existing trees start bearing fewer nuts. The objective of this study was to analyze the economic performance of a range of representative combinations of annual crops, berries, and fast-bearing fruit trees in reforestation and afforestation plots. This included hypothetical timber utilization in order to be able to bridge the income gap until newly planted walnut trees bear nuts. Data were based on semistructured household and expert interviews. In all plots there was grassy vegetation, which was harvested for hay. In some of the plots, corn and potatoes were grown as annual crops. Additionally, in part of the plots apple and berries were grown next to walnuts. The net present value of the farming systems for a 20-year period was highest for the 2 systems that included hypothetical timber utilization. Walnut and haymaking performed worst, with a negative net present value. All non-timber systems yielded an income gap until around year 10, when walnut trees begin to fruit.

Cities at the fringe of the Taklimakan desert in NW China are prone to dust and sand storms with serious consequences for human well-being. The Kökyar Protection Forest was established in the 1980s as an ecological engineering project with the intent of protecting the city of Aksu, NW China, from these impacts. It is designed as a combination of poplar shelterbelts and orchards, irrigated by river water from the Aksu River, the main tributary of the Tarim River. Prevalent literature describes it as an afforestation project for combatting desertification with manifold positive effects for the economic, social, and environmental dimension of sustainable development. This paper sets out to challenge these claims by a sustainability assessment in which the plantation is examined from a broader perspective, embedding it to the wider context of social and environmental problems in South Xinjiang. Methods comprise evapotranspiration calculations, interviews, a socioeconomic household survey, stakeholder dialogues, and literature research. Results affirm its economic sustainability, but see a mixed record for the social sphere. From the nature conservation point of view, it has to be classified as unsustainable because its high irrigation water consumption results in the downstream desiccation and desertification of natural riparian forests along the Tarim River, causing a forest loss in the downstream area twice the size of the forest gain in the upstream area. There is a trade-off between artificial shelterbelt plantations for urban ecosystem services on the one hand side, and natural riparian forests and their biodiversity on the other hand side. The paper recommends restricting agricultural extension, and using locally adapted less water consuming agroforestry schemes to protect urban dwellers from dust stress.

To understand the spatial structure of monospecific Tugai forests (Xinjiang Province, China) growing as gallery woods nourished by ground water, root suckering in Populus euphratica was studied by a combination of morphological and molecular analyses. Seedlings grow a deep tap root and keep this as adult trees, whereas root suckers never develop a tap root but utilize the horizontally stretching root of their parent trees. The resulting reverse “T” root architecture distinguishes reliably even adult root suckers from generatively grown trees. Due to assimilate input from the root sucker, the distal root (pointing away from the parent tree) becomes thicker soon than its proximal root, which allows determination of the direction of vegetative growth. One stand including 279 young trees germinated from seeds and 267 root suckers was mapped completely, and selected suckers were assigned to parent trees by genotyping with microsatellite DNA. Root suckers develop up to 40 m away from parent trees on horizontal “spacer” roots, usually originating not deeper than 20 cm below surface. Trees begin with root suckering between 10 and 15 years, shortly before reaching flowering age. Cutting experiments indicated reduced survival of young root suckers disconnected from the parent tree. Without a tap root and with a rooting point close to the surface, declining ground water levels should lower the fitness of root suckers even more than that of generatively grown trees.

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 basin, located in Xinjiang, NW China, is the largest endorheic river basin in China and one of the largest in all of Central Asia. Due to the extremely arid climate, with an annual precipitation of less than 100 mm, the water supply along the Aksu and Tarim rivers solely depends on river water. This is linked to anthropogenic activities (e.g., agriculture) and natural and semi-natural ecosystems as both compete for water. The ongoing increase in water consumption by agriculture and other human activities in this region has been enhancing the competition for water between human needs and nature. Against this background, 11 German and 6 Chinese universities and research institutes have formed the consortium SuMaRiO (Sustainable Management of River Oases along the Tarim River; http://www.sumario.de), which aims to create a holistic picture of the availability of water resources in the Tarim River basin and the impacts on anthropogenic activities and natural ecosystems caused by the water distribution within the Tarim River basin. On the basis of the results from field studies and modeling approaches as well as from suggestions by the relevant regional stakeholders, a decision support tool (DST) will be implemented that will then assist stakeholders in balancing the competition for water, acknowledging the major external effects of water allocation to agriculture and to natural ecosystems. This consortium was formed in 2011 and is funded by the German Federal Ministry of Education and Research. As the data collection phase was finished this year, the paper presented here brings together the results from the fields from the disciplines of climate modeling, cryology, hydrology, agricultural sciences, ecology, geoinformatics, and social sciences in order to present a comprehensive picture of the effects of different water availability schemes on anthropogenic activities and natural ecosystems along the Tarim River. The second objective is to present the project structure of the whole consortium, the current status of work (i.e., major new results and findings), explain the foundation of the decision support tool as a key product of this project, and conclude with application recommendations for the region. The discharge of the Aksu River, which is the major tributary of the Tarim, has been increasing over the past 6 decades. From 1989 to 2011, agricultural area more than doubled: cotton became the major crop and there was a shift from small-scale to large-scale intensive farming. The ongoing increase in irrigated agricultural land leads to the increased threat of salinization and soil degradation caused by increased evapotranspiration. Aside from agricultural land, the major natural and semi-natural ecosystems are riparian (Tugai) forests, shrub vegetation, reed beds, and other grassland, as well as urban and peri-urban vegetation. Within the SuMaRiO cluster, focus has been set on the Tugai forests, with Populus euphratica as the dominant tree species, because these forests belong to the most productive and species-rich natural ecosystems of the Tarim River basin. At sites close to the groundwater, the annual stem diameter increments of Populus euphratica correlated with the river runoffs of the previous year. However, the natural river dynamics cease along the downstream course and thus hamper the recruitment of Populus euphratica. A study on the willingness to pay for the conservation of the natural ecosystems was conducted to estimate the concern of the people in the region and in China's capital. These household surveys revealed that there is a considerable willingness to pay for conservation of the natural ecosystems, with mitigation of dust and sandstorms considered the most important ecosystem service. Stakeholder dialogues contributed to creating a scientific basis for a sustainable management in the future.

Opinions vary on fertilization strategies in part because of uncertainties in methods assessing P supply across sites. We quantified the fate and extractability of fertilizer P after two to four crops with four to five P levels applied to upland rice (Oryza sativa L.)-soybean [Glycine max (L.) Merr.] rotations in three experiments in Asia. Soil P pools were measured by Mehlich-1 extractant, a modified Hedley fractionation and by mixed-bed resin capsules after 1 and 14 d (resin adsorption quantity, RAQ-P 1 and RAQ-P 14 ). Without P addition, 84% of the total P was in the NaOH-P o and residual-P fractions across sites. Phosphorus fertilization increased Mehlich-1 P, resin-P, NaOH-P 1 , H 2 SO 4 -P, RAQ-P 1 , and RAQ-P 14 across sites, whereas NaOH-P o and residual-P were unchanged. The sum of resin-P and NaOH-P; increased from 10% to between 20 and 30% of the total soil P. Mehlich-1 P and resin P increased similarly across sites and fitted quadratic models: the increase in Mehlich-1 P (mg kg -1 per kg P ha -1 ) ranged from 0.050 at low P rates to >0.125 at >400 kg P ha -1 . The increases per unit P of RAQ-P, NaOH-P i , and H 2 SO 4 -P varied among sites. Oxalate-extractable Fe accounted for most of the variation in NaOH-P i and RAQ-P. Changes in soil P pools in tropical upland Oxisols and Ultisols following P addition are likely better reflected by NaOH-P, and RAQ-P than Mehlich-1 P and resin P. Improvements in soil P tests are needed to better discriminate the changes in P pools from fertilization across soils.