Impact of agricultural land use in Central Asia: a review

International audienceAbstractAgriculture is major sector in the economy of Central Asia. The sustainable use of agricultural land is therefore essential to economic growth, human well-being, social equity, and ecosystem services. However, salinization, erosion, and desertification cause severe land degradation which, in turn, degrade human health and ecosystem services. Here, we review the impact of agricultural land use in the five countries of Central Asia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan, during 2008–2013 in 362 articles. We use the Land Use Functions framework to analyze the type and relative shares of environmental, economic, and social topics related to agricultural land use. Our major findings are (1) research on land use in Central Asia received high levels of international attention and the trend in the number of publications exceeded the global average. (2) The impacts of land use on abiotic environmental resources were the most explored. (3) Little research is available about how agricultural land use affects biotic resources. (4) Relationships between land degradation, e.g., salinization and dust storms, and human health were the least explored. (5) The literature is dominated by indirect methods of data analysis, such as remote sensing and mathematical modeling, and in situ data collection makes up only a small proportion

Research on Land Use Functions in Central Asia: A bibliometric analysis

Agriculture is the backbone of Central Asia’s (CA) economy providing economic and social stability in the region. Sustainable use of agricultural land is therefore of critical importance to economic growth, human well-being and social equity, and ecosystem services. However, severe land degradation through salinization, erosion and desertification is evident and respective impacts on human health and ecosystem services are suspected. This paper aims to analyze current research on agricultural land use in CA through applying the Land Use Functions framework. In particular, it examines the type and relative shares of environmental, economic and social aspects of agricultural land use addressed in existing scientific literature. This study analyzed scientific publications dealing with agricultural land use in five CA countries: Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan. A systematic database search of international peer-reviewed articles was conducted using the ISI Web of Science. We selected the English-language articles that were published between 2008 and 2013. After the analysis of paper titles, abstracts and keywords, we found 362 articles relevant to agricultural land use in CA. The analysis indicated that publications concentrating on environmental and economic dimensions of land use functions were primary focus of land use scientists. By contrast, social aspects of land use functions, such as employment, human health and recreational services, and landscape aesthetics received far less importance by international scholars. Interestingly, large portion of articles focused on issues of agricultural land use in Uzbekistan. This is due to the fact that the country extensively benefited from large international research projects in the last decade. By applying the Land Use Functions framework, we identified international research focus and knowledge gaps that future scientists can contribute to the sustainability of agricultural land use in CA

Cytokinins and polar transport of auxin in axillary pea buds

The influence of cytokinin on auxin transport during release of axillary buds from apical dominance was studied. Expression of auxin-carrier coding genes PsAUX1 (AUXIN RESISTANT 1) and PsPIN1 (PIN-FORMED 1) was explored in axillary buds of the 2nd node of 7-day pea plants (Pisum sativum L.) cv. Vladan after decapitation or after exogenous application of benzyladenine (6-benzylaminopurine) onto axillary buds of intact plants. Localization of the PsPIN1 protein, the key factor for polar transport of auxin in axillary buds, was visualised by immunohistochemistry. After exogenous application of cytokinin the expression of PsAUX1 and PsPIN1 rapidly increased with a simultaneous rapid decrease in PsDRM1 and PsAD1 expression – genes related to bud dormancy. The same changes in expression were observed after decapitation, however they were markedly slower. The PsPIN1 auxin efflux carrier in the inhibited axillary buds of intact plants was localised in a non-polar manner. After exogenous application of cytokinin gradual polarisation of the PsPIN1 protein occurred on the basal pole of polar auxin transport competent cells. Despite the fact that direct auxin application to buds of intact plants led to an increase in PsAUX1 and PsPIN1 expression, the buds remained dormant (non-growing) what was accompanied by persistent expression of the dormancy markers PsDRM1 and PsAD1. The results indicate a possible effect of cytokinins on biosynthesis, and/or transport of auxin in axillary buds and they highlight the importance of auxin-cytokinin crosstalk in the regulation of bud outgrowth after breaking of apical dominance

How much information do we gain from multiple-year sampling in natural pond research?

Natural ponds are perceived as spatially and temporally highly variable ecosystems. This perception is in contrast to the often-applied sampling design with high spatial but low temporal replication. Based on a data set covering a period of six years and 20 permanently to periodically inundated ponds, we investigated whether this widely applied sampling design is sufficient to identify differences between single ponds or single years with regard to water quality and macrophyte community composition as measures of ecosystem integrity. In our study, the factor “pond”, which describes differences between individual ponds, explained 56 % and 63 %, respectively, of the variance in water quality and macrophyte composition. In contrast, the factor “year” that refers to changes between individual years, contributed less to understand the observed variability in water quality and macrophyte composition (10 % and 7 % respectively, of the variance explained). The low explanation of variance for “year” and the low year-to-year correlation for the single water quality parameter or macrophyte coverage values, respectively, indicated high but non-consistent temporal variability affecting individual pond patterns. In general, the results largely supported the ability of the widely applied sampling strategy with about one sampling date per year to capture differences in water quality and macrophyte community composition between ponds. Hence, future research can be rest upon sampling designs that give more weight to the number of ponds than the number of years in dependence on the research question and the available resources. Nonetheless, pond research would miss a substantial amount of information (7 to 10 % of the variance explained), when the sampling would generally be restricted to one year. Moreover, we expect that the importance of multiple-year sampling will likely increase in periods and regions of higher hydrological variability compared to the average hydrological conditions encountered in the studied period

Dissipation of Micropollutants in a Rewetted Fen Peatland: A Field Study Using Treated Wastewater

In the present study, a mixture of treated wastewater and surface water was used to rewet a degraded fen peatland site during a three-year rewetting experiment. We studied the behavior and effects of micropollutants by means of hydrological, physico-chemical, microbiological and ecotoxicological monitoring. The highest concentrations of micropollutants in the treated wastewater were found for the pharmaceuticals carbamazepine and diclofenac, some metabolites, the sweetener acesulfame, tolyl- and benzotriazole and diatrizoate. In the underlying, shallow groundwater where treated wastewater application for rewetting had been expected to have the greatest impact due to seeping and evapotranspiration processes, only a sporadic occurrence of micropollutants was found. The influence of dilution by groundwater movements was examined by applying a geohydrological model. The sorption of micropollutants onto the peaty soil also played a role, as found for carbamazepine. Further processes such as photolysis, microbial decay under low redox conditions and plant uptake can be assumed to be relevant for the removal of many substances. Ecotoxicity tests with the soil before and after rewetting did not indicate any negative impact on the soil habitat quality by wastewater application, but clearly pointed at ecotoxicologically relevant geogenic arsenic concentrations at the study site. Although a positive effect on receiving surface water systems is expected if wastewater is applied on land instead of discharged to water bodies, the rewetted soil may turn into a sink for micropollutants in the long term. Hence, the findings of the present field study encourage further investigations in order to identify the governing processes in the elimination of micropollutants in rewetted peatlands flooded with treated wastewater

Forensic hydrology: what function tells about structure in complex settings

Facing the challenges of the European Water Framework Directive and competing demands requires a sound knowledge of the hydrological system. This is a major challenge in regions like Northeast Germany. The landscape has been massively reshaped during repeated advances and retreats of glaciation during the Pleistocene. This resulted in a complex setting of unconsolidated sediments with high textural heterogeneity and with layered aquifer systems, partly confined, but usually of unknown number and extent of single aquifers. The Institute of Landscape Hydrology aims both at a better understanding of hydrological processes and at providing a basis for sustainable water resources management in this region. That would require sound information about the respective regions of interest that are rarely available at sufficient degree of detail. Thus, there is urgent need for alternative approaches. For example, time series of groundwater head, lake water level and stream runoff do not only depend on (unknown) geological structures, but in turn can reveal information about major geological features. To that end, different approaches have been developed and successfully applied at different scales, based both on advanced time series analysis and dimension reduction approaches and on well-known and rather simple methods. This approach has been coined “forensic hydrology”: Like in a crime story, numerous pieces of evidence are combined in a systematic way to end up with a consistent conceptual model about the prevailing cause–effect relationships. An example is given for the Quillow catchment in Northeast Germany in a rather complex geological setting