Land Use Indicators Research Articles

Evaluation and Adaptation of the Land Degradtion Neutrality Approach to Land Classification Resources in the Kyrgyz Republic

Work on the study and adaption of the concept and methodological basis of land degradation neutrality (LDN) in the Kyrgyz Republic was launched in 2016 as part of a corresponding project. The Secretariat of the United Nations Convention to Combat Desertification (UNCCD) provided the country with a comprehensive set of indicators and information derived from an analysis of global satellite data reflecting key indicators of land degradation in the Kyrgyz Republic. This data set was analyzed at the national level via comparison with data from studies and a series of meetings and consultations with relevant state and nonstate institutions. As a result of the research, a team of national experts was able to compare international (UNCCD data) and national land-use indicators. In particular, a comparative analysis was carried out based on categories of land resources. Nevertheless, the work requires further detailed verification of international and national land use indicators with alternative satellite data, as well as special field studies.

Research on Land Use Change in Hanzhong City Based on RS

This paper studies the land use change status and development direction in Hanzhong City in recent years. The four remote sensing image data of Hanzhong City in 90 years, 00 years, 05 years and 10 years are selected, and the maximum likelihood ratio classification method is selected in ERDAS software. The land use types are divided into six categories, namely, forest land, grassland, water area, cultivated land, construction land, and unused land. The land use area changes, speed changes, and degree changes are analyzed. The results show that Hanzhong City has been used for 20 years. The area of forest land and construction land is increasing. The area occupied by water, grassland, cultivated land and unused land is decreasing. The annual rate of change in land use is low, and there is a tendency to rise first and then fall. From the comprehensive index of land use, Hanzhong The land use degree of the city is relatively high. Generally speaking, the land use of Hanzhong City is in an adjustment period and has a large development space.

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.

Land use as a driver for protist community structure in soils under agricultural use across Europe

Soil biodiversity is threatened by intensification of land use. The consequences of different land use on belowground biodiversity remain insufficiently explored for soil protists. Alongside being abundant and extremely diverse in soil, protists provide many ecosystem services: key players in the microbial loop, turnover of organic matter and stimulation of plant growth-promoting rhizobacteria. However, we lack knowledge of effects of site, land use intensity and management on diversity of soil protists. Here we assessed protist communities in four European arable sites with contrasting land use intensities at each site: Lusignan, France; Moskanjci, Slovenia; Castro Verde, Portugal and Scheyern, Germany as well as two grassland sites: Hainich, Germany and Lancaster, UK. Each site has consistent agricultural management history of low and high land use intensities quantified in terms of land use index (LUI). We employed high-throughput sequencing of environmental DNA, targeting the V4 region of the 18S rRNA gene. By assigning the protist composition to trophic groups, we inspected for effects of management, and other biotic and abiotic variables. While overall protist richness was unaffected by LUI within sites, specific trophic groups such as plant pathogens and saprotrophs were affected. Effects on protist biome across land uses and sites were also observed. LUI sensitive taxa were taxonomically diverse in each plot, and their trophic groups responded in specific patterns to specific practices. The most abundant trophic group was phagotrophs (73%), followed by photoautotrophs (16%), plant pathogens (4%), animal parasites (2%) and saprotrophs (1%). Community compositions and factors affecting the structure of individual trophic groups differed between land uses and management systems. The agricultural management selected for distinct protist populations as well as specific functional traits, and the protist community and diversity were indeed affected by site, LUI and management, which indicates the ecological significance of protists in the soil food web.

Land use and land cover control on the spatial variation of dissolved organic matter across 41 lakes in Mississippi, USA

While dissolved organic matter (DOM) is an important indicator of water quality, land use and land cover (LULC) of watersheds define the source, quality, and quantity of DOM delivered to a waterbody. This study examined the influence of various LULC classes in the spatial distribution of DOM in 41 lakes across the state of Mississippi. To scale the influence of LULC classes on DOM distribution, we have classified 41 lakes into five clusters based on DOM compositions determined by parallel factor analysis. Four major DOM compositions including terrestrial humic-like (C1), microbial humic-like (C2), soil-derived humic-like (C3), and tryptophan-like or tyrosine like (C4) components were identified. Higher amounts of terrestrial humic-like and soil-derived humic-like DOM compositions were observed in lakes within watersheds dominated by forested, barren, wetlands, or agricultural areas with exposed unconsolidated soil. Higher amounts of microbial humic-like composition were observed in lakes surrounded by hay/pasture, rangeland, and urbanized areas. Additionally, protein-like DOM and ammonia were more enriched in larger lakes, indicating the influences of photochemical reactions. High amounts of forested areas and higher concentrations of terrestrial humic-like DOM composition were identified in all lakes suggesting forested areas in the watershed as the principal source of DOM in Mississippi lakes.

Understanding variations in activity-based vehicle allocation decisions: A latent segmentation-based random parameter logit modeling approach

This paper examines the activity-based vehicle allocation decisions among individuals during mandatory and discretionary activity-tours based on travel accompanying arrangements, specifically, solo travel (i.e. traveling alone) and joint travel (i.e. traveling with household/non-household members). Latent segmentation-based random parameter logit (LSRPL) models are developed in this study to explore the factors affecting vehicle allocation decisions within households, including travel characteristics, built environment and accessibility measures. For instance, model results suggest that presence of children in joint mandatory- and discretionary activity-tours increases individuals’ probability of getting SUVs from their households’ existing vehicle fleet. Also, tour complexity identified by higher number of activity stops, exhibits positive coefficient value for SUV allocation in case of discretionary activity-tours. One of the unique features of this study includes evaluating the effects of individuals’ attitudes on vehicle allocation decisions at activity-based tour-level. For example, due to positive attitude towards active transportation, likelihood of allocating any vehicle to the individuals decrease during both solo and joint mandatory activity-based tours. The vehicle allocation decisions in the households, however, vary across two segments. Older-higher income individuals in segment one tend to get SUVs from their household vehicle fleet during a joint discretionary activity-tour while living in higher mixed land-use areas, however, younger-lower income individuals in segment two exhibit a negative relationship for SUVs. In addition to the heterogeneity across segments, preference of SUVs during a joint discretionary activity-tour might vary among individuals within the same segment, as indicated by statistically significant standard deviation of ‘land-use index’ variable.

Conjugation of artificial humic acids with inorganic soil matter to restore land for improved conservation of water and nutrients

AbstractArtificial soil (AS) with a dark–brown appearance and high soil organic matter (SOM) was manufactured under hydrothermal conditions from poor sandy landfill using the 'hydrothermal humification process.' This approach may retrosynthesize the natural clay–humin complex, which is the main contributor for water and ion binding in fertile, natural soils. The structure and morphology of as‐created organic–inorganic composites was examined, and it was shown that the as‐created artificial SOM (A‐SOM) indeed tightly binds to the mineral surfaces, thus creating remediated soil or more general AS. A‐SOM does not change the bulk structure of the involved inorganic minerals but activates their surface. Depending on the biomass used as the starting product, the high effectivity of synthetic humification improves the organic carbon and nitrogen content when compared with the employed sandy soil (SS). The composition was adjusted to be comparable with a reference sample of cultivated soil (2.92% in C content and 7.8% in SOM) to enable a fair referencing. We then analyzed the most frequently used soil quality indicators for agricultural land use and found strong water retention and nutrient conservation, which reflects the successful restoration of mineral–humus conjugation. Pure ASs provide superior performance in the analyzed series, whereas simulated soils (mixture of SS and AS) still exhibit satisfactory capacities of water and ion bonding. The values were found to be very similar to cultivated soils sampled from Germany and Harbin, China.

METHODOLOGICAL APPROACH TO THE INTEGRAL ASSESSMENT OF THE REGIONAL LANDS USE TERRITORIAL DEVELOPMENT

The relevance of the research topic is caused by the need to ensure the territorial development of land use at the regional level. In this context, it is necessary to form a quantitative basis for assessing territorial development, which will make decisions in the field of land use and ensure the growth of land use efficiency in the region, considering spatial, urban planning, ecological and investment areas. As a result of the study, a methodological approach to the integrated assessment of the territorial development of land use in the region has been proposed. Its development is based on the application of principles and includes a set of interrelated stages. It was established that the formation of a complex of spatial, urban planning, investment, and ecological factors, which influence the territorial development of land use in the region is carried out on the basis of the analysis and systematization of existing scientific and methodological developments and regulatory support. An algorithm for the development and implementation of a methodological approach to an integrated assessment of the territorial development of land use in the region is proposed. It forms a closed system, which allows to develop and implement a methodological approach by applying of information support, appropriate methods and models to achieve a result on the growth of the integral indicator of land use in the region, considering spatial, urban planning, investment, and ecological characteristics. Based on the developed method, an estimated basis for the territorial development of land use in the region, adoption of justified decisions, regarding the formation and implementation of spatial, urban planning, investment, and ecological areas is created.

Relations of dissolved-oxygen variability, selected field constituents, and metabolism estimates to land use and nutrients in high-gradient Boston Mountain streams, Arkansas

Continuous monitoring data can be extremely useful for assessing water-quality conditions particularly for variables, such as dissolved oxygen, that exhibit dynamic diel swings. As a means of evaluating stream dissolved oxygen criteria used by the Arkansas Department of Environmental Quality (ADEQ), we compared continuous dissolved oxygen (DO) data collected at five small- to moderate-sized (watersheds 10-100 mi2), high-gradient streams in the Boston Mountains distributed across a land-use and nutrient condition gradient. The sampled streams exhibit a general pattern established for other aquatic systems (e.g., larger streams, low-gradient streams, and lakes) where increasing land-use intensity results in increased nutrient concentrations, stream eutrophication, and increased DO variability. DO concentrations were < 6 mg/L for fewer than 4% of measurements at the two sites identified "a priori" as least disturbed by nutrient and land-use indices, while concentrations at the three sites identified as moderately and most disturbed were < 6 mg/L for 20 to 33% of measurements. These findings demonstrate that the current criterion (10% of the DO measurements are < 6 mg/L) employed by ADEQ was effective at identifying various degrees of DO impairment in Boston Mountain streams. Our analysis also demonstrated that continuous pH and specific conductance data and estimates of stream metabolism were helpful for attributing DO variability to anthropogenic or natural origins. Considerations that were useful for examining these relationships and evaluating ADEQ's DO criterion should be applicable to DO studies in other locations where stream and geologic characteristics are similar to those of the Boston Mountains.

Environmental Differences between Migratory and Resident Ungulates—Predicting Movement Strategies in Rocky Mountain Mule Deer (Odocoileus hemionus) with Remotely Sensed Plant Phenology, Snow, and Land Cover

Migration is a valuable life history strategy for many species because it enables individuals to exploit spatially and temporally variable resources. Globally, the prevalence of species’ migratory behavior is decreasing as individuals forgo migration to remain resident year-round, an effect hypothesized to result from anthropogenic changes to landscape dynamics. Efforts to conserve and restore migrations require an understanding of the ecological characteristics driving the behavioral tradeoff between migration and residence. We identified migratory and resident behaviors of 42 mule deer (Odocoileus hemionus) based on GPS locations and correlated their locations to remotely sensed indicators of forage quality, land cover, snow cover, and human land use. The model classified mule deer seasonal migratory and resident niches with an overall accuracy of 97.8% and cross-validated accuracy of 81.2%. The distance to development was the most important variable in discriminating in which environments these behaviors occur, with resident niche space most often closer to developed areas than migratory niches. Additionally, snow cover in December was important for discriminating summer migratory niches. This approach demonstrates the utility of niche analysis based on remotely sensed environmental datasets and provides empirical evidence of human land use impacts on large-scale wildlife migrations.

Chemical and Physical Controls on Mercury Source Signatures in Stream Fish from the Northeastern United States.

Streams in the northeastern U.S. receive mercury (Hg) in varying proportions from atmospheric deposition and legacy point sources, making it difficult to attribute shifts in fish concentrations directly back to changes in Hg source management. Mercury stable isotope tracers were utilized to relate sources of Hg to co-located fish and bed sediments from 23 streams across a forested to urban-industrial land-use gradient within this region. Mass-dependent isotopes (δ202Hg) in prey and game fish at forested sites were depleted (medians -0.95 and -0.83 ‰, respectively) in comparison to fish from urban-industrial settings (medians -0.26 and -0.38 ‰, respectively); the forested site group also had higher prey fish Hg concentrations. The separation of Hg isotope signatures in fish was strongly related to in-stream and watershed land-use indicator variables. Fish isotopes were strongly correlated with bed sediment isotopes, but the isotopic offset between the two matrices was variable due to differing ecosystem-specific drivers controlling the extent of MeHg formation. The multivariable approach of analyzing watershed characteristics and stream chemistry reveals that the Hg isotope composition in fish is linked to current and historic Hg sources in the northeastern U.S. and can be used to trace bioaccumulated Hg.

Can dragonfly and damselfly communities be used as bioindicators of land use intensification?

Abstract There is a growing need to identify efficient biological indicators for assessing accelerated land use intensification, as well for understanding the effects of past environmental changes on species distributions. To address this, we used an extensive opportunistic survey dataset of 254 adult odonate (suborder Anisoptera or dragonflies; suborder Zygoptera or damselflies) species collected in nine Mexican hydrological regions during two time windows (1980–1993 and 1994–2010). We evaluated species richness, body size and individual species’ response to land use intensification over time at a national scale using Phylogenetic Bayesian Regression Mixed Models. We found that dragonfly species serve as good indicators of current land use, whereas damselfly species show time-lagged effects of land use intensification. Large species could thus be used as a proxy of recent reduction of original vegetation, whereas small species provide information on historic habitat modification. Odonate body size seems to be a better variable for measuring the integrity of original vegetation than the more commonly used species richness. Finally, the use of individual species as bioindicators at broad spatial and temporal scales is not encouraged, as it does not reflect the degree of ecological integrity, and only the occurrence of some species combinations can indicate environmental degradation.

Variação espaço-temporal (1938-2013) do uso e ocupação da terra na região do Saco da Fazenda, Itajaí-SC

O objetivo deste trabalho é a análise da variação temporal da cobertura de uso e ocupação do solo de uma região estuarina no litoral centro-norte do Estado de Santa Catarina, reconstruindo as alterações na dinâmica da paisagem em um período de 75 anos (1938 - 2013), além de calcular as variações do Índice de Uso e Ocupação do Solo (IUO) e do Índice de Cobertura Vegetal (ICV). Para a classificação digital de uso e ocupação do solo foi realizada uma classificação visual, em ambiente SIG. Os resultados indicaram que nas décadas de 30, 50 e 70 ocorreram as maiores transformações na área de estudo, sendo que a variação do IUO apontou um crescimento das áreas antropizadas e o ICV demonstrou uma redução das áreas com vegetação. Estudos desta natureza constituem-se ferramentas importantes para a tomada de decisão dos gestores municipais, na busca de um crescimento mais harmônico das cidades, compatibilizando as necessidades dos moradores por moradias e serviços públicos com os remanescentes naturais, que tem igual importância para a qualidade de vida da população.

Relationships between diatom metrics based on species nutrient traits and agricultural land use.

We assessed how diatom metrics were related to different ranges of agricultural land use. Diatom assemblage composition, nutrients, and landscape characteristics were determined at 232 sites in eight agriculturally dominated study areas of the continental United States. Two regional groups based on differences in diatom relations to human disturbance were determined. Changes in diatom species composition were related to nutrients, pH, and conductivity in the eastern study areas (due to more wetlands) and more exclusively to nutrients in the west-central study areas. Homogenization of diatom flora among streams was related to high agricultural disturbance at this transcontinental scale. Species traits were developed separately for the east and west-central study groups and calculated two ways: indicator species analysis for taxa in low and high TN or TP conditions and weighted average partial least squares models of TN and TP concentration. These diatom metrics were significantly related to many indicators of agricultural land use in watersheds, especially percent row crops. Further analysis was conducted on only the west-central region due to its larger sample size. Overall, diatom metrics using species responses to N gradients were better related to agricultural land use than were species responses to P gradients. Most nutrient-based diatom metrics changed greatly in response to low ranges of percent row crops, but only a few high N diatom metrics responded to high row crop conditions. The greater response of diatoms to changes in low agriculture conditions may be due to past diatom evolution occurring when most waters had low nutrient conditions.

Farm Level Indicators of Sustainable Land Management: Effect on Agricultural Production in Oyo State, Nigeria

Farmland sustainability and increased agricultural production have been a major concern of average farmers in Nigeria especially in South Western part of the Country. The study examines the farm level indicators and their effects on agricultural production among rural farmers. Multi-stage methods of sampling technique were used to select fifty respondents for this study using a well-structured questionnaire. Data collected were analyzed by the use of descriptive such as means, percentage, standard deviation and fuzzy logic analysis. The result shows that average age of farmer, farm size, household size and farming experience are 52.28 years, 2.072 hectare, 6.80 and 29.42 years of farming experience respectively. The fuzzy logic method was used to compute the composite indicator of sustainable land use (ISLU) which was 0.2843 indicating that farmers' land management practices in the study area are generally sustainable with the current application of the indicators. Land fallowing, trends of vegetative cover, irrigation, pesticide used among others contributed a higher percentage of land use sustainability with about 3.8% each, while minimum tillage, cover crops, crop rotation and cassava cutting use had no contribution to land use sustainability. The study recommends that rural water should be made available and that informal training through extension services should be conducted to educate farmers on sustainable land management (SLM) practices in order to have a better environment and improve production in the study area.

Soil parameters, land use, and geographical distance drive soil bacterial communities along a European transect

To better understand the relationship between soil bacterial communities, soil physicochemical properties, land use and geographical distance, we considered for the first time ever a European transect running from Sweden down to Portugal and from France to Slovenia. We investigated 71 sites based on their range of variation in soil properties (pH, texture and organic matter), climatic conditions (Atlantic, alpine, boreal, continental, Mediterranean) and land uses (arable, forest and grassland). 16S rRNA gene amplicon pyrosequencing revealed that bacterial communities highly varied in diversity, richness, and structure according to environmental factors. At the European scale, taxa area relationship (TAR) was significant, supporting spatial structuration of bacterial communities. Spatial variations in community diversity and structure were mainly driven by soil physicochemical parameters. Within soil clusters (k-means approach) corresponding to similar edaphic and climatic properties, but to multiple land uses, land use was a major driver of the bacterial communities. Our analyses identified specific indicators of land use (arable, forest, grasslands) or soil conditions (pH, organic C, texture). These findings provide unprecedented information on soil bacterial communities at the European scale and on the drivers involved; possible applications for sustainable soil management are discussed.

Nilai Kebolehpercayaan dan Koefisien Kappa Kriteria Pengurusan Sisa Pepejal Perbandaran dalam Perancangan Guna Tanah di Malaysia

In 2016, 95 % of the collected wastes are taken to 156 disposal facilities that are distributed throughout the Peninsular Malaysia, yet municipal solid waste (SPP) open dumping of is common wherever land is available. Previous studies show that the land use activities influence the waste generation. The issue of non-compliance such as illegal change of land use zoning and conflicts in development plans are among others that affect the environment sustainability. Therefore, the objective of this study is to calculate the reliability and coefficient of kappa value of municipal solid waste management criteria for land use planning in Malaysia. It is to identify the most important SPP management indicators during land use planning by valuing its reliability and kappa coefficient. This list of indicators can be used as references for land use planning by local authorities as well as one of SPP management steps towards sustainable development. Content analysis techniques were used in this study where journals, thesis, project reports and research report have been used in this research. The results show that waste collection, landfill, 3R, governance, education, stakeholders and services (n=7) are an important indicator of land use planning to ensure the sustainability of SPP management with alpha value, α=0.887. The results also show that governance is the most commonly used criteria in the MSW management as their role as decision makers and financial aspect needs, with a value of κ=0.837.

The use of agri-environmental measures to address environmental pressures in Germany: Spatial mismatches and options for improvement

The European Union has introduced agri-environmental measures (AEM) as one key policy tool to counteract the adverse impact of modern agriculture on the environment. Payments for AEM currently account for about 7% (i.e. nearly 20 billion EUR) of total EU funding for the Common Agricultural Policy programming period 2014-2020. It has been argued that the conditions for disbursing these payments are not rigorous enough to generate environmental benefits. A lack of spatial targeting as well as insufficient consideration of synergies and trade-offs among policy objectives has also been criticized. Here we present the first nationwide analysis on the spatial distribution of agri-environmental payments and their correlation to selected environmental pressure and land-use indicators in Germany. We focused on the AEM payments of the financial year 2014. The results revealed spatial mismatches between the distribution of AEM payments and some indicators for environmental pressures. Uptake of AEM tended to be low in regions with high ammonium deposition or high shares of utilized agricultural area on organic soils. In contrast, AEM uptake was high in regions with a high risk of soil erosion and habitat fragmentation. Moreover, agri-environmental payments varied significantly in relation to land-use attributes across Germany. More farmers received AEM payments in regions with high shares of grassland and Natura 2000 protected areas than did those in regions characterized by intensive agriculture (high numbers of livestock, high area of utilized agricultural area per farm and high natural yield potential). In general, there was a tendency towards spatial separation between highly specialized, productive agricultural areas exposed to comparatively severe environmental pressures and regions with small-scale, low-input farming exposed to lower environmental pressures that maintained a more balanced supply of regulating and cultural ecosystem services. We conclude that AEM need to be more attractive to land managers, especially in productive agricultural regions, in order to increase their effectiveness for environmental impact reduction.

Global warming potential and total material requirement in metal production: Identification of changes in environmental impact through metal substitution

In view of the increasing demand for metal use, it is of significant importance to evaluate the environmental impact of metal production. The global warming potential (GWP) in the process of metal production has often been focused upon as a major indicator for evaluating the burden on the environment. Moreover, the environmental impact and mineral exploitation arising from metal ore mining activities, which generate unavoidable mine wastes and have an impact on the ecological biodiversity, cannot be ignored. The major factors for determining the intensity of resource exploitation being the ore grades and strip ratio, the existing indicators for land use employed in the life cycle assessment (LCA) may not fully cover the criteria of the impact of metal mining on the environmental system. Therefore, this study employs the method of total material requirement (TMR) assessment, involving not only the direct and indirect material inputs but also the hidden flows, which are particularly associated with mine wastes. Firstly, the methodology of computing the TMR in the process of metal production is developed. Next, the relation between the GWP and TMR for 58 metals is assessed and finally, the environmental impact through metal substitutes is evaluated from the perspectives of the GWP and TMR. This analysis could identify some of the aspects overlooked in the previous environmental criteria that were concentrating on greenhouse gas emissions and global warming. The developed algorithm may be useful in identifying appropriate metal substitutes, considering the environmental impact.

Sensitivity of young water fractions to hydro-climatic forcing and landscape properties across 22 Swiss catchments

Abstract. The young water fraction Fyw, defined as the proportion of catchment outflow younger than approximately 2–3 months, can be estimated directly from the amplitudes of seasonal cycles of stable water isotopes in precipitation and streamflow. Thus, Fyw may be a useful metric in catchment inter-comparison studies that investigate landscape and hydro-climatic controls on streamflow generation. Here, we explore how Fyw varies with catchment characteristics and climatic forcing, using an extensive isotope data set from 22 small- to medium-sized (0.7–351 km2) Swiss catchments. We find that flow-weighting the tracer concentrations in streamwater resulted in roughly 26 % larger young water fractions compared to the corresponding unweighted values, reflecting the fact that young water fractions tend to be larger when catchments are wet and discharge is correspondingly higher. However, flow-weighted and unweighted young water fractions are strongly correlated with each other among the catchments. They also correlate with terrain, soil, and land-use indices, as well as with mean precipitation and measures of hydrologic response. Within individual catchments, young water fractions increase with discharge, indicating an increase in the proportional contribution of faster flow paths at higher flows. We present a new method to quantify the discharge sensitivity of Fyw, which we estimate as the linear slope of the relationship between the young water fraction and flow. Among the 22 catchments, discharge sensitivities of Fyw are highly variable and only weakly correlated with Fyw itself, implying that these two measures reflect catchment behaviour differently. Based on strong correlations between the discharge sensitivity of Fyw and several catchment characteristics, we suggest that low discharge sensitivities imply greater persistence in the proportions of fast and slow runoff flow paths as catchment wetness changes. In contrast, high discharge sensitivities imply the activation of different dominant flow paths during precipitation events, such as when subsurface water tables rise into more permeable layers and/or the river network expands further into the landscape.