Riparian Land Use Research Articles

城镇化背景下河流生境评价——以深圳市为例

城镇化背景下，河流生态系统退化趋势明显，有效评价河流生境状况是修复和保护河流生态系统健康的重要基础。深圳市作为全国经济发展的窗口城市，河流生境的调查研究十分匮乏。因此，为阐明深圳市不同城镇化程度的流域河流生境的差异与主要影响因素，对深圳市两个代表性流域的河流生境展开了研究。针对深圳市河流的生境特点，于2019年丰水期（8月）和枯水期（11月）对城镇化程度较高的深圳河流域的13个样点和城镇化程度较低的坪山河流域12个样点河段的生境状况进行定量调查与评价。采用综合评价法，从河床、河道和河岸带3个方面选取10个生境指标，构建深圳市河流生境评价指标体系和评价方法。结果表明：深圳河流域河流生境质量总体较差，生境评价等级为"良"、"中"、"差"的样点河段分别占7.7%、38.5%、53.8%；坪山河流域河流生境质量总体较好，生境评价等级为"优"、"良"、"中"、"差"的样点河段分别占8.3%、41.7%、41.7%、8.3%。方差分析结果表明两次调查河流生境状况无显著性差异，短时间跨度内河流生境状况变化较小；两个流域河流生境状况差异显著，城镇化程度较低的坪山河流域河流生境质量显著好于城镇化程度较高的深圳河流域。河流生境评估指标主成分分析结果表明人类活动强度、河岸稳定性、河道变化、底质、河岸土地利用及植被多样性是影响深圳市河流生境变化的主要因子。本文对河床、河道、河岸带3个方面分别提出针对性的修复建议，对深圳市河流的生境修复和保护具有重要的指导作用。;In the context of urbanization, the degradation of river ecosystems has become increasingly prominent. Consequently, effectively assessment of river habitat conditions is an important foundation for restoration and protection of river ecosystem health. Shenzhen, as a window or opening city of China’s economic development, has extremely limited research conducted related to river habitat conditions. Therefore, in order to accurately elucidate the differences and main influencing factors of river habitats in basins with different degrees of urbanization in Shenzhen, a habitat assessment study was conducted on streams and rivers in two representative basins in Shenzhen. Based on characteristics of river habitats in Shenzhen, quantitative investigation and assessment of habitat conditions were conducted in 13 sampling sites in the highly urbanized Shenzhen River Basin and 12 sampling sites in the less urbanized Pingshan River Basin, in both wet (August) and dry (November) seasons in 2019. We adopted a comprehensive evaluation method to select 10 key habitat indicators from three categories: river bed, river channel, and riparian zone, to construct the habitat assessment index system and assessment method for Shenzhen rivers. The results showed that the overall condition of river habitat in the Shenzhen River Basin was poor, and the habitat condition of river sections with good, fair and poor were 7.7%, 38.5%, and 53.8%, respectively. The overall condition of river habitat in the Pingshan River Basin was good, and the habitat condition of river sections with excellent, good, fair and poor were 8.3%, 41.7%, 41.7%, and 8.3%, respectively. The analysis of variance (ANOVA) results showed that there was no significant difference in river habitat conditions between the two seasons, which indicated that the overall river habitat conditions did not change too much in the short time period. There were significant differences in river habitat conditions between the two basins, and the overall river habitat condition of the less urbanized Pingshan River Basin was significantly better than that of the highly urbanized Shenzhen River Basin. Principal components analysis (PCA) results of river habitat assessment indices showed that human activity intensity, riparian stability, river channel modifications, substrate composition, riparian land use and vegetation diversity were the main factors driving river habitat conditions in Shenzhen. Based on the results of the river habitat assessment in Shenzhen, targeted restoration and management recommendations were proposed from three aspects: riverbed, river channel, and riparian zone, which have important implications for river habitat restoration and ecological conservation in Shenzhen.

Do water quality, land use, or benthic diatoms drive macroinvertebrate functional feeding groups in a subtropical mountain stream?

ABSTRACT Feeding strategies are traits that reflect the adaptation of a species to environmental conditions. Macroinvertebrates are an important primary consumer in stream food webs, but the abiotic and biotic drivers of functional feeding groups (FFGs), which are categorized based on feeding strategies, require additional clarification. The aim of our study was to quantify the contributions of abiotic factors (water quality and land use at different scales) and biotic factors (important primary producers, such as epilithic diatoms) to the variation of FFGs of macroinvertebrates in the Jinshui River, upper Han River Basin, China, a subtropical mountain river. We conducted campaigns in the Jinshui River during high stream flow (August 2009), low flow (November 2009), and normal flow (April 2010). We performed redundancy analysis and multiple factor analysis to evaluate the relationships among riparian land use at different scales, water quality, the benthic diatom community, and FFGs. We found that water quality, especially the fluoride ion (F−), metals (chromium and cadmium), and chemical oxygen demand, significantly correlated with FFGs, and that the benthic diatom community, especially Ceratoneis arcus var. linearis f. recta and Denticula tenuis, explained a high proportion of the variation in FFGs. The benthic diatom community was significantly correlated with water quality, and variations in FFGs were poorly explained by upstream riparian land use at the entire upstream scale and reach scale (2 km upstream). Further, water quality and the benthic diatom community were significantly correlated with riparian land use at the reach scale. Our findings on how the water quality, riparian land use, and diatom community influence FFGs will provide the scientific foundation for biodiversity research of macroinvertebrate FFGs, conservation of the food web, and management of the riparian zone.

Effects of riparian deforestation on benthic invertebrate community and leaf processing in Atlantic forest streams

Riparian deforestation may strongly affect stream functioning, with consequences for biodiversity and ecosystem services. These effects can be assessed using bioindicators relating to biotic community structure and ecosystem functioning. We evaluated the effects of riparian deforestation on 1. measures of community structure using aquatic benthic invertebrates, and 2. an aspect of ecosystem functioning, aquatic leaf processing. We selected sites along gradients of riparian land use in four Atlantic rainforest streams and measured physical and chemical properties for their association with riparian deforestation. We sampled benthic invertebrates and calculated metrics of community structure at each site. We measured rates of leaf processing using leaves of a common riparian tree, Guarea guidonia. Riparian deforestation was accompanied by increasing concentration of ammonia, water current and temperature and decreasing nightly oxygen saturation. Invertebrate diversity decreased and community metrics changed with deforestation as expected of negative impacts. Leaf processing decreased with deforestation. Although there were significant differences in physical and chemical measurements among streams, the gradients in community and ecosystem responses were similar, thus suggesting that both types of bioindicators were useful for monitoring changes and relating them to loss of biodiversity and ecosystem function.

Riparian Land-Use, Stream Morphology and Streambank Erosion within Grazed Pastures in Southern Iowa, USA: A Catchment-Wide Perspective

Factors influencing streambank erosion at the field/reach scale include both watershed and riparian land-uses, stream hydrology and channel morphology at the catchment scale. This study assesses the relationship of riparian land-uses, stream morphologic characteristics and catchment scale variables to streambank erosion within grazed riparian pastures in the Southern Iowa Drift Plain. Thirteen cooperating beef cow–calf farms and their catchments ranging from 2.5 to 12.9 km2 in the Rathbun Lake watershed in South Central Iowa (USA) were chosen to conduct this study. Results suggest that the integration of stream morphologic characteristics and riparian land-uses at both the reach and catchment scale are necessary to explain the current level of streambank erosion measured at the reach scale. Larger catchment size or catchments with more total channel length were found to experience more bank erosion at the reach scale. A significant positive relationship between percent sand-and-silt in the bank soil and bank erosion rates implies that bank soils with less cohesiveness are more erodible. Catchment-scale assessments of the thirteen watersheds showed that within the 50 m corridor on both sides of the stream, 46 to 61% of riparian area was devoted to agricultural use and only 6 to 11% was in ungrazed perennial vegetation, much of it enrolled in the USDA Conservation Reserve Program. Overall, this and previous Rathbun watershed studies have shown that intensive agricultural use of riparian areas over such extents of time and scale could be directly (in field scale) and/or indirectly (watershed scale) related to excessive amounts of streambank erosion (ranging from 8.6 to 38.3 cm/yr) to receiving streams and lakes leading to their impairment and reduction in ecological services. Exclusion of cattle grazing in the riparian areas along buffered stream lengths (2.1% of the total watershed area) of the Rathbun watershed would reduce this impact. This approach could also be applicable to other similar watersheds with extensive land-use under grazed management.

Structure, distribution patterns and ecological responses to hydrological changes in benthic macroinvertebrate assemblages in a regulated semi-arid river: baseline for biomonitoring studies

Biological monitoring requires a comprehensive baseline of assemblage distribution patterns and their environmental drivers. In this study we evaluated benthic macroinvertebrates in a regulated river, located in a semi-arid region, which has a seasonal flood pulse and is affected by several anthropogenic pressures. Taxonomic and trophic structures of benthic macroinvertebrate assemblages were analysed in terms of their longitudinal distribution, hydrological regime and environmental factors, including the effects of hydromorphology, riparian land use and water abstraction. Most taxa were generalists and classified in the collector–gatherer functional feeding group. A large taxonomic replacement was associated with hydromorphological characteristics. Local environmental variables were critical for macroinvertebrate assemblages. There was significant temporal variability regarding seasonal flood pulse. Water abstraction for irrigation had a strong effect on assemblage structure. We suggest some challenges and issues for successful implementation of biomonitoring tools in the Dulce River, related primarily to high spatiotemporal variability.

Riparian land-use systems impact soil microbial communities and nitrous oxide emissions in an agro-ecosystem

Riparian buffer systems (RBS) are considered a best management practice (BMP) in agricultural landscapes to intercept soil nitrogen (N) and phosphorus (P) leaching and surface runoff into aquatic ecosystems. However, these environmental benefits could be offset by increased greenhouse gas (GHG) emissions, including nitrous oxide (N2O). The main sources of N2O in soil are linked to processes which are mediated by soil microbial communities. These microorganisms play crucial roles in N-cycling and in the reduction of nitrate to N2, and N2O gases. This study was conducted to determine the abundance and diversity of microbial communities and functional genes associated with N-cycling and their influence on N2O emissions in different riparian land-use: undisturbed natural forest (UNF), rehabilitated site (RH), grass buffer (GRB), and an adjacent agricultural land (AGR). Soil was sampled concurrently with N2O emissions on July 13, 2017. DNA was extracted and used to target key N-cycling genes for N-fixation (nifH), nitrification: (amoA), and denitrification (nirS, nirK, and nosZ) via quantitative PCR, and for high throughput sequencing of total bacterial and fungal communities. Non-metric multidimensional scaling (NMDS) was used to examine microbial community composition and indicated significant differences in bacterial (p < 0.001) and fungal (p < 0.0085) communities between sites. Bacterial abundance differed significantly (p = 0.0005) between RBS and AGR sites with the highest populations occurring in the UNF (2.1 × 1010 copies g−1 dry soil), and lowest in AGR (5.3 × 109 copies g−1 dry soil). However, the AGR site had the highest ammonia-oxidizing bacteria (AOB) abundance, indicating that nitrification is highest at this site. The abundance of the nosZ gene was highest in RH and GRB demonstrating the capacity for complete denitrification at these sites, lowering measured N2O. These results suggest N-cycling microbial community dynamics differ among RBS and are influencing N2O emissions in the sites investigated.

Riparian land use and stream habitat regulate water quality

Riparian land use is a key driver of stream ecosystem processes but its effects on water quality are still a matter of debate when proposing measures to improve freshwater quality. The aim of this study was to examine the influence of riparian land use on stream habitat and water chemistry, and to assess in what extent stream habitat also affects water quality. To that end, we selected eight reaches in the Ave River basin (northwestern Portugal) and compared longitudinal variations in water chemistry and stream habitat between reaches with different land use (urban, agricultural and natural), and between reaches with natural riparian areas and different habitats. Stream habitat was assessed using the Fluvial Functional Index, the HABSCORE, and the Riparian Forest Quality Index. Longitudinal variations in water chemistry were determined measuring differences in concentrations of ammonium, nitrate, phosphate and oxygen, and conductivity, pH and temperature between the downstream and the upstream ends of each reach. Nitrate concentration tended to decrease along reaches with more natural riparian areas and to increase along reaches with more urban and agricultural land uses. Longitudinal variations in water chemistry also differed between reaches with natural riparian areas, suggesting that water quality also depends on stream habitat. Moreover, longitudinal variation in water chemistry was proven a simple, useful and low-cost approach to assess the influence of land cover and stream habitat on water quality. Overall results demonstrated that both riparian land use and stream habitat influence water quality and that riparian forests are essential to reduce nutrient export to downstream ecosystems.

Effects of land use on water quality in a River Basin (Daning) of the Three Gorges Reservoir Area, China: Watershed versus riparian zone

Water quality is important for domestic, industrial, agricultural and environmental purposes, and is reported to be strongly affected by land use including land use composition, configuration and intensity, whereas, the linkages are highly variable at multiple spatial and seasonal scales. We evaluated the land use effects on water quality in a typical river basin (Daning River Basin) of the Three Gorges Reservoir Region (TGRR), through comparing watershed and riparian zones. Multiple spatial-temporal scales of land use and water quality in this region are rare, while it is important for water conservation for the world largest reservoir – the Three Gorges Reservoir. Consequently, to quantitatively explore the multi-temporal and spatial impacts of land use on water quality in the Daning River Basin, we used multivariate statistical and empirical models, and indicators of land use for water quality were therefore developed. The redundancy analysis (RDA) reported that the effect of land use on overall water quality parameters was the strongest at watershed scale both in the wet and dry seasons. As regards riparian land use effects, 200 m, 300 m and 500 m buffer zones was slightly stronger during the wet season than the dry season, but the other buffer scales (i.e., 50 m, 100 m and 400 m buffer zones) were the opposite. The most important explanatory variable (MIEV) was water in multiple buffer zones, whereas the MIEV in watershed scale was Shannon’s diversity index (SHDI) across seasons. Multiple linear regression (MLR) modeling reported that the linkages between single water quality parameter and land use variables were highly dependent on hydrological seasonality and spatial sales. Water, landscape shape index (LSI) and SHDI were the main predictors of riverine water quality. Water and SHDI were positively correlated with total nitrogen (TN), total dissolved nitrogen (TDN) and total phosphorus (TP), LSI was negatively correlated with TP. We highlight the importance of multiple time-space scales for understanding the impacts of anthropogenic activities (e.g., land use) on water quality, which could provide key information of land use planning for water conservation, and developing land use indicators for water quality.

Aquatic ecosystem health assessment of a typical sub-basin of the Liao River based on entropy weights and a fuzzy comprehensive evaluation method

River ecosystem health assessments provide the foundation for river ecological protection and integrated management. To evaluate the aquatic ecosystem health of the Fan River basin, benthic macroinvertebrate indices (the Multimeric Macroinvertebrates Index Flanders (MMIF) and Family Biotic Index (FBI)), a habitat index (the river habitat quality Index (RHQI)) and a water quality index (the Improved Water Pollution Index (IWPI)) were selected. The entropy weighting method was used to calculate the RHQI and IWPI. A fuzzy comprehensive evaluation method was used to evaluate the aquatic ecosystem health. The evaluation results indicated that the aquatic ecosystem health of the Fan River basin was better in 2018 than in 2011, which respectively belonged to the ends of the 11th and 12th Five-Year Plans of the Major Science and Technology Programs for Water Pollution Control and Treatment in China. The proportions of sampling stations with good, moderate and poor grades in 2011 were 50.0%, 40.0% and 10.0%, respectively, and in 2018, the proportions of stations with excellent, good and moderate grades were 20.0%, 50.0% and 30.0%, respectively. A correlation analysis showed that the RHQI was significantly correlated with the MMIF, FBI and IWPI. The riparian land use pattern was an important factor that influenced changes in the aquatic ecosystem health grade. Of the water quality parameters, total phosphorous (TP) and potassium bichromate index (COD) were the main factors that affected the characteristics of benthic macroinvertebrates and the aquatic ecosystem health.

Conversion of tropical forests to agriculture alters the accrual, stoichiometry, nutrient limitation, and taxonomic composition of stream periphyton

AbstractThe conversion of forests to agriculture in tropical areas profoundly changes adjacent streams by modifying hydrological conditions, altering light regimes, and increasing nutrient concentrations. In this study, we used an integrative approach to examine how transformations of intact forests affected the physical, chemical, and biological properties of periphyton, in three Brazilian Atlantic rainforest streams. We found that riparian land use change affected the stream periphyton in a variety of ways that were linked to the availability of light and nutrients. Periphyton standing stocks and accrual rates of new periphyton biomass on tiles were higher in deforested reaches than forested reaches. Linear mixed‐model analyses showed that the increase of chlorophyll‐a in the periphyton was explained by the increase in deforestation and soluble reactive phosphorus concentration. Deforestation also altered periphyton stoichiometry as deforested streams exhibited lower C:P, whereas C:N ratios decreased with increasing NH4+ concentration that was higher in some deforested reaches. Periphyton productivity appeared to be limited by light in forested reaches and by nutrients in deforested reaches. There was differential availability of nitrogen and phosphorus in the deforested reaches, depending on land use type, and this resulted in different nutrient limitation. Periphyton community structure shifted from taxa less tolerant to high nutrients and light found in forested sites, to species tolerant to these conditions dominating periphyton assemblages in deforested sites. The loss of canopy cover was the strongest predictor of community composition for all sites, whereas phosphorus concentration was the best predictor of algal abundance in deforested reaches. This study highlights the complex effects of forest clearing on stream periphyton, ranging from changes to biomass accrual, nutrient limitation, stoichiometry, and community structure. We show the importance of using a comprehensive approach to help determine and predict how deforestation impacts stream ecosystems.

The Influence of Riparian Corridor Land Use on the Pesquería River’s Macroinvertebrate Community (N.E. Mexico)

The Earth’s freshwater ecosystems are currently under threat, particularly in developing countries. In Mexico, intensive land use and inadequate monitoring policies have resulted in the severe degradation of the country’s freshwater ecosystems. This study assesses how the macroinvertebrate communities in the Pesquería River, located in Northeastern Mexico, are affected by riparian land use, in order to determine their potential use as bioindicators to evaluate the macroinvertebrate integrity of the Pesquería River. First, we characterized the land use cover in the riparian channel. Second, we sampled 16 sites for benthic macroinvertebrates along the main channel during the wet and dry seasons. Third, we evaluated the influence of the riparian channel land use on the macroinvertebrate community using 42 different biological metrics. The land use characterization depicted a riparian channel mainly influenced by agricultural and urban land use. Eighty-one invertebrate taxa were identified during the study. Permutational analysis of the variance analysis confirmed significant differences across the different land use classes and the macroinvertebrate community composition while no differences were found between seasons. The indicator species analysis revealed 31 representative taxa for natural land use, 1 for urban, and 4 for agricultural land use. Our modelling analysis showed that 28 of the 42 biological metrics tested responded significantly to land use disturbances, confirming the impact of land use changes on the Pesquería River’s macroinvertebrate communities and suggesting that these metrics may have a use as bioindicators. Finally, this study may provide significant biological information for further studies in similar conditions.

Riparian Land-Use Impacts on Stream Bank and Gully Erosion in Agricultural Watersheds: What We Have Learned

Stream bank and gully erosion are major sources of nonpoint source pollutants, especially in landscapes dominated by agriculture. Implementation of upland conservation practices in landscapes dominated by agriculture reduces upland sediment transport more than water runoff, leading to excessive stream bank and gully erosion. This review focus on ten different studies conducted in streams in Iowa that investigated riparian land-use impacts on stream banks, gullies, and other riparian sediment sources (cattle loafing areas and cattle stream access points). The riparian land-uses investigated were riparian forest buffers; grass filters; continuous, rotational, and intensive rotational pastures; pastures with cattle fenced out of the stream; and row-cropped fields. Results of these studies indicate that maintaining perennial deep-rooted vegetation in riparian areas and excluding cattle from the stream channel stabilizes stream banks and gullies. Cattle loafing areas and cattle stream access points appear to also be important sediment sources. Re-establishing perennial riparian vegetation is a sustainable and cost-effective conservation practice because it reduces sediment in streams while maintaining the majority of the watershed in agricultural production. The limited available funds for the implementation of holistic watershed conservation practices suggest using targeted approaches, at the watershed scale, to improve conservation practice effectiveness.

太子河大型底栖动物摄食功能群对河岸带土地利用类型的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 太子河大型底栖动物摄食功能群对河岸带土地利用类型的响应 DOI: 10.5846/stxb201809011865 作者: 作者单位: 大连海洋大学水产与生命学院,大连海洋大学水产与生命学院,大连海洋大学水产与生命学院,大连海洋大学水产与生命学院,北京师范大学水科学研究院,中国环境科学研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 辽宁省优秀人才支持计划项目（LR2015009）；国家水体污染控制与治理科技重大专项（2015ZX07202012）；辽宁省"兴辽英才计划"项目（XLYC1807228） Response of riparian land-use types to functional groups of benthic macroinvertebrates in Taizi River, Liaoning Province Author: Affiliation: Liaoning Provincial Key Laboratory for Hydrobiology,College of Fisheries and Life Science,Dalian Ocean University,Liaoning Provincial Key Laboratory for Hydrobiology,College of Fisheries and Life Science,Dalian Ocean University,Liaoning Provincial Key Laboratory for Hydrobiology,College of Fisheries and Life Science,Dalian Ocean University,Liaoning Provincial Key Laboratory for Hydrobiology,College of Fisheries and Life Science,Dalian Ocean University,College of Water Science,Beijing Normal University,Laboratory of Riverine Ecological Conservation and Technology,Chinese Research Academy of Environmental Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为研究太子河大型底栖动物摄食功能群对河岸带土地利用类型的响应关系，于2012年5月对太子河流域底栖动物和水环境因子和土地利用类型进行野外调查及数据分析。结果表明：1）太子河流域底栖动物群落在4种不同土地利用类型内具有极显著差异，平均丰度、Shannon-Wiener多样性指数和Pielou均匀度指数在森林用地中最高，分别为8.86、0.73和0.94，平均密度在森林耕作用地中最高（782.75个/m2），除食碎屑者功能群（S），其他摄食功能群在不同土地利用类型内无差异（P > 0.05）。2）太子河土地利用类型与水环境因子之间的Pearson分析表明，森林用地与EC、TDS、TN、NH3-N、CODMn之间呈显著负相关性，与DO、IOS之间呈显著正相关性；耕地与DO和IOS之间呈显著负相关性；城镇用地与EC、TDS和TN之间呈正相关性。3）太子河土地利用类型与底栖动物功能群之间的Spearman分析表明森林用地与食碎屑者（S）、刮食者（SC）和收集者（GC）呈正相关性。耕地与食碎屑者（S）、滤食者（FC）之间呈负相关性，城镇用地与刮食者（SC）和收集者（GC）之间呈显著负相关性。4）底栖动物功能群和水环境因子之间的典范对应分析表明，食碎屑者（S）功能群主要受底质指数（IOS）驱动，其他功能群与环境因子之间无相关性。因此，水环境因子和底栖动物群落参数比摄食功能群更能反映人类活动对土地利用的改变，水环境和底栖动物群落研究可为河岸带土地利用保护提供理论依据。 Abstract:River ecosystems are the most affected habitats globally by human activities, such as the changes of land use in the riparian of river. Macroinvertebrate is an important component of aquatic organisms in freshwater ecosystems and is an important biological indicator of bio-assessment in rivers. Macroinvertebrates have been widely used to evaluate the interference and impact of human activities on river ecosystems. Here, we aim to understand the effects of different land use types on the feeding function groups of macroinvertebrate and to evaluate the responses of macroinvertebrates to changes of riparian land use types in the Taizi River Basin (TRB). Based on data of 42 sites, we found that the macroinvertebrate communities were significantly different in four land use types. The average abundance,Shannon-Wiener diversity index, and Pielou evenness of macroinvertebrates were the highest values in the forest land with 8.86, 0.73 and 0.94, respectively. There were significant negative correlations of forest land and EC, TDS, TN, NH3-N, and CODMn using Pearson analysis, and between farmland and DO, IOS. By Spearman analysis, the results indicated that forest land was positively correlated with shredders, scrapers and collector-gatherers, while farmland was negatively correlated with shredders and collector-filterers. Canonical correspondence analysis showed that shredders were mainly driven by IOS. In general, the environmental factors and macroinvertebrate community reflect change of human activities more effectively than the functional groups based on our study. The research on water environment and macroinvertebrate community structure can provide a theoretical basis for riparian land use protection. 参考文献 相似文献 引证文献

Land use modifies Odonata diversity in streams of the Brazilian Cerrado

The presence of riparian vegetation provides microclimatic regulation of stream conditions [e.g. luminosity (lux), air temperature (°C) and relative humidity (%)], which varies naturally throughout the day. These variables explain the diurnal behaviour patterns of ectotherms such as Odonata in natural areas. However, human land uses (e.g. pastures) modify the abiotic conditions of riparian environments, favouring the presence of disturbance-tolerant species. In this context, we assess relationships between riparian land use (control streams-natural areas and pasture), abiotic conditions habitat integrity index (in control and pastures streams), (air temperature, luminosity and humidity in control streams), and Odonata diversity (between pasture and control streams and throughout the time of day) in Brazilian savannah (Cerrado) streams. First, the control streams had higher habitat integrity index than pasture. Higher abundance and difference in composition of Odonata species were observed in streams surrounded by pasture relative to natural areas. The conversion of natural areas to pasture near streams was also accompanied by an increase in overall body size of Odonata species. Odonata species richness and abundance in natural areas varied throughout the day, but peaked around 12:00 h, coinciding with changes in air temperature and luminosity. Our study highlights that changes in the physical characteristics of streams through conversion of natural habitats to pasture will change environmental conditions and act as a filter on the distribution and persistence of Odonata species in Cerrado streams.

Riparian forests mitigate harmful ecological effects of agricultural diffuse pollution in medium-sized streams

Agricultural pollution persists as a significant environmental problem for stream ecosystems. Uncultivated buffer zones or reforestation of riparian zones are advocated as a key management option that could compensate the harmful land use impacts. The effectiveness of riparian forests to protect ecological conditions of agricultural streams is yet inconclusive, particularly regarding the benefit of riparian buffers in streams suffering from uninterrupted agricultural diffuse pollution. We studied the effects of riparian land use on periphyton production and diatom, macrophyte and benthic macroinvertebrate communities in medium-sized agricultural streams by a) comparing 18 open field and forested agricultural stream reach pairs that only differed by the extent of riparian forest cover, and b) comparing the agricultural reaches to 15 near-natural streams. We found that periphyton abundance was higher in open reaches than in the forested reaches, but diatom community structure did not respond to the riparian forest cover. Macrophyte and macroinvertebrate communities were clearly affected by the riparian forest cover. Graminoids dominated in open reaches, whereas bryophytes were more abundant in forested reaches. Shredding invertebrates were more abundant in forested reaches compared to open reaches, but grazers did not differ between the reach types. Macrophyte trait composition and macroinvertebrate community difference between the reaches were positively related to the difference in riparian forest cover. The community structure of all three groups in the agricultural streams differed distinctly from the near-natural streams. However, only macrophyte communities in forested agricultural reaches showed resemblance to near-natural composition. Our results suggest that riparian forests provide ecological benefits that can partly compensate the impacts of agricultural diffuse pollution. However, community structure of forested agricultural reaches did not match the near-natural composition in any organism group indicating that catchment-scale management and mitigation of diffuse pollution need to be still advocated to achieve ecological goals in stream management and restoration.

Effects of riparian land use changes on soil aggregates and organic carbon

Soil aggregation processes play a crucial role in re-establishing soil structure and function, and protecting soil organic carbon (SOC) to sustain soil fertility and quality. There is a strong interest in preventing soil erosion in the interface of terrestrial and aquatic ecosystem. The relationship between soil aggregates and SOC in riparian zones is not as well studied as in terrestrial ecosystems. The aim of this study was to investigate the effects of conversion of abandoned lands to cultivated lands on organic carbon (C) and soil structure. Soil samples and plant residues were collected from abandoned lands and cultivated lands which had been converted from abandoned lands over 10 years ago. Results show that SOC content and storage increases by 1.64 times and 6.75 Mg hm−2, respectively, after the land use change. For cultivated lands, 11.94% of macro-aggregates (>2 mm) were broken into micro-aggregates (<2 mm), resulting in the mean weight diameter (MWD) and geometric mean diameter (GMD) decreases of 1.01 and 1.11 mm, respectively, while the fractal dimension (FD) increased by 0.28. The SOC content of micro-aggregates (10.88–15.02 g kg−1) was higher than that of macro-aggregates (10.10–11.63 g kg−1) for both abandoned and cultivated lands. The SOC content of micro-aggregates for cultivated lands (14.46–15.02 g kg−1) was higher than abandoned lands (10.80–11.14 g kg−1). The content of microbial biomass carbon (MBC) increased by 1.52 times due to increases in root biomass and the plant residue returned to soil, which were mainly caused by the changes in cultivation practices and soil water conditions. Our results show that total SOC storage increased by the land use conversion from abandoned to cultivated lands, indicating that planting aquatic plants might be an effective method of preventing C loss from riparian ecosystems. The findings of this study provided insights into the changes in soil aggregates and soil C sequestration following the land use changes in riparian areas.

Tracing of particulate organic C sources across the terrestrial-aquatic continuum, a case study at the catchment scale (Carminowe Creek, southwest England)

Soils deliver crucial ecosystem services, such as climate regulation through carbon (C) storage and food security, both of which are threatened by climate and land use change. While soils are important stores of terrestrial C, anthropogenic impact on the lateral fluxes of C from land to water remains poorly quantified and not well represented in Earth system models. In this study, we tested a novel framework for tracing and quantifying lateral C fluxes from the terrestrial to the aquatic environment at a catchment scale. The combined use of conservative plant-derived geochemical biomarkers n-alkanes and bulk stable δ13C and δ15N isotopes of soils and sediments allowed us to distinguish between particulate organic C sources from different land uses (i.e. arable and temporary grassland vs. permanent grassland vs. riparian woodland vs. river bed sediments) (p<0.001), showing an enhanced ability to distinguish between land use sources as compared to using just n-alkanes alone. The terrestrial-aquatic proxy (TAR) ratio derived from n-alkane signatures indicated an increased input of terrestrial-derived organic matter (OM) to lake sediments over the past 60years, with an increasing contribution of woody vegetation shown by the C27/C31 ratio. This may be related to agricultural intensification, leading to enhanced soil erosion, but also an increase in riparian woodland that may disconnect OM inputs from arable land uses in the upper parts of the study catchment. Spatial variability of geochemical proxies showed a close coupling between OM provenance and riparian land use, supporting the new conceptualization of river corridors (active river channel and riparian zone) as critical zones linking the terrestrial and aquatic C fluxes. Further testing of this novel tracing technique shows promise in terms of quantification of lateral C fluxes as well as targeting of effective land management measures to reduce soil erosion and promote OM conservation in river catchments.

Checklist of Benthic Macroinvertebrate Taxa Along Different Riparian Land Use Types in Alaknanda River Catchment of the Central Himalaya, Uttarakhand (India)

A checklist of benthic macroinvertebrates recorded at 08 different riparian land use (RLU) types in Alaknanda river catchment (ARC) in the Central Himalaya (India) is provided here. Among 77 taxa recorded, 73 insect genera belonged to 09 orders and 52 families at different RLU types. Majorities were nymphs and larvae of Ephemeroptera, Plecoptera, Trichoptera, Coleoptera, Lepidoptera, Odonata, Hemiptera, Megaloptera and Diptera. The highest number of insect taxa (50) was recorded from Dense Mixed Forest; whereas, the lowest (27) was recorded from barren site i.e., Montane Barren. Also, the forested site had most number of common taxa (25). Benthic macroinvertebrates at Chir Pine Forest serves as a link between Dense Mixed Forest and Open Mixed Forest. Agricultural sites had 36 taxa in common. Interestingly the agricultural sites share 24 taxa with the forested sites. Overall 13 benthic insect taxa were ubiquitous in ARC, while 15 were rare, confined to a single site.

Effect of riparian land use on environmental conditions and riparian vegetation in the east African highland streams

Agricultural land use is expanding and at an accelerated rate. In Ethiopia, most of this expansion has occurred in highland areas and involve deforestation of natural riparian vegetation. However, the impacts on the water quality of streams are poorly understood, especially with regard to the influence of land use patterns on highland streams. In this study, we investigated the effects of land use modifications on the water quality and riparian condition of highland streams and examined whether the preservation of riparian vegetation would help mitigate the negative impacts of intensive agriculture practices. Our results show significant differences in the water quality of streams with different land use. Several parameters commonly used to indicate water quality, such as the concentrations of orthophosphate, turbidity, and suspended solids were significantly higher in the agricultural streams than in the forest stream. The preservation of riparian vegetation in the surrounding highland streams was associated with overall better riparian condition, floristic quality, and water quality such as lower turbidity, total suspended solids, orthophosphate, and higher dissolved oxygen. We conclude, that increases in vegetation cover improved riparian condition and water quality relative to other non-vegetated areas. Therefore, we strongly recommend the preservation of riparian vegetation in tropical highland streams surrounded by intensive agriculture. More studies on the effects of best management practices in areas dominated by agriculture can greatly improve our capacity to prevent the degradation of water quality in tropical highland streams of Africa.

Macroinvertebrate community in relation to water quality and riparian land use in a substropical mountain stream, China.

Exploring how water quality and land use shape the benthic macroinvertebrate community composition is of widespread interest in biodiversity conservation and environmental management. In this study, we investigated the structures of benthic macroinvertebrate assemblages and their environmental controls in terms of water quality and riparian land use in the Jinshui River, China. We carried out three campaigns including wet season (August 2009), dry season (November 2009), and normal season (April 2010) based on the hydrological regime in Jinshui basin. The result showed that macroinvertebrate assemblage variations were better explained by water quality factors than land use based on variance partitioning procedure. The land use of 2km upstream from the sampling sites had explained more variation than that of the whole riparian zone in upstream catchment on macroinvertebrate community, and land use of 2km upstream also had more interactions with water quality. Canonical correspondence analysis (CCA) indicated that the elements or nutrient of magnesium (Mn), selenium (Se), strontium (Sr), silicon (Si), dissolved inorganic nitrogen (DN), sulfur (S), total organic carbon (TOC), and total nitrogen (TN) in water exhibited a strong relationship with macroinvertebrate assemblages. However, the variance in water quality explained by land use was lower than that explained by water quality in rivers using redundancy analysis. Our study suggested that proximate factors (i.e., water quality) were more important to interpret the macroinvertebrate community compared to ultimate factors (i.e., land use) for macroinvertebrate assemblages in river system.