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Humans have altered river flows leading to a loss of connection with floodplain habitats. The expansion of agriculture in floodplains has resulted in landscapes dominated by irrigated farmland. A key challenge in water management is to conserve existing ecological communities and habitat heterogeneity, while simultaneously maintaining engineered infrastructure for agriculture. In this study, we focused on an artificial channel network for irrigation with a regulated flow regime and its function as habitat for various fish species. Differences in hydraulic conditions among channels and compositional changes in fish species were examined to clarify functional flow heterogeneity. Analyzed using pairwise Simpson dissimilarity among sampling reaches, species turnover was positively associated with Froude number (flow intensity) differences at intermediate discharges, and with differences in cross‐sectional areas (flow magnitude) at low discharges. Drastic changes in inflows should be considered for the effective conservation of flow heterogeneity, even under a regulated flow regime. Improved engineering design to manage the hydraulic environment is one option for maintaining the ecological value of lateral waterbodies in human‐dominated landscapes. Our findings provide insights into the importance of functional flow heterogeneity to conserve fish species diversity. [ABSTRACT FROM AUTHOR]

Ecological resilience to ungulate overbrowsing is an important issue in forest ecosystems. After chronic herbivory, the recovery rate of understory vegetation and its related functions can be slow even with decreasing grazing intensity; thus, detecting elasticity during alternative successional trajectories is fundamental to understanding state perturbations. In this context, we focused on physical plant–soil feedback (functional interactions between plant growth and soil physical conditions) and evaluated elasticity and recovery processes according to deer density. The effects of 40 years of chronic herbivory by sika deer (average density 14.7 individuals km−2) on the recovery of understory plant communities and associated changes in soil physical properties in headwater catchments were assessed. Using 8 years of catchment‐wide exclusion (fenced) and reduction (only culled; average 4.3 individuals km−2) treatments, plot sampling was conducted in 2010 (before treatment) and 2018 (after treatment). The recovery of vegetation and soil physical properties were evaluated, and functional plant–soil relationships and spatial variability were assessed to detect recovery processes during alternative successional trajectory. Woody species increased only under the exclusion treatment and the average soil bulk density was lower than that under reduction treatments. Soil bulk density was negatively correlated with root biomass in the fenced catchment, and root biomass was positively associated with woody species richness. Reduced soil bulk density (~0.5 g cm−3) was observed with greater root biomass and woody species richness on upper hillslopes in the deer‐excluded catchment where plant coverage was minimal. Successional failure under the reduction treatment suggested slow recovery with a depressed threshold according to deer density, indicating a clockwise hysteretic response to deer density. Unlike plant coverage during the earlier period of overbrowsing, woody species root development led the recovery of functional physical plant–soil feedback; however, this was probably limited by the higher soil erosion rate in riparian areas and an under‐developed herb layer. Our results highlight an alternative recovery trajectory of physical plant–soil feedback driven by an alternative plant element (woody roots) to recovery trajectory with increasing plant cover. However, riparian erosion and herb layer would still suppress recovery. Therefore, recovery might be slower at the landscape scale. [ABSTRACT FROM AUTHOR]

When forest disturbance impacts adjacent headwater streams, the recovery of habitat conditions and populations can take over several decades. Thus, considering long‐term, historical legacies of forest disturbances is key for understanding and managing forest–stream linkages. We focused on small‐scale forest disturbances such as small‐block harvesting and landslides. We compared the long‐term (past 100 years) cumulative effects between the anthropogenic and natural forest disturbances on stream conditions and the abundance of a headwater specialist, Scopura montana (Plecoptera: Scopuridae).Sampling was conducted in 10 m reaches of 39 first‐order streams with a catchment area up to 5.9 ha during late summer in central Japan. We quantified past clearcut logging areas using plantation records of each harvest block and past landslide areas from contour maps within each catchment.Piecewise structural equation models using the cumulative area of each forest disturbance as an independent variable, revealed different indirect effects of clearcut logging (average area: 1.74 ha) and landslides (0.21 ha) on S. montana abundance through modified stream conditions. Canopy openness and wetted channel width were higher with a larger logged area, and S. montana abundance was lower with higher water temperature (daily maximum). When the magnitude of clearcut logging was similar to the landslide area (<0.77 ha), the negative relationship between water temperature and S. montana abundance was also significant in the model. Streambed roughness and wetted channel width were greater with larger landslide area but there were no significant links between stream conditions and S. montana abundance.Our results suggest that clearcut logging can cause long‐term impacts by exposing the stream surface to solar radiation owing to delayed canopy closure. The preference of S. montana is for cold water conditions in summer. Controlling forest harvesting along streams could benefit forest–stream management, as could including consideration of disturbance‐driven cycles for sustaining headwater populations. [ABSTRACT FROM AUTHOR]

Riparian fluvial systems are used for the irrigation of rice. This practice has led to an increasing need to conserve biodiversity of these riparian systems against intensification of rice　irrigation systems. This study examined the underlying processes that structure fish community assemblages in a traditional rice irrigation system and how these processes might inform conservation programmes., Sampling was conducted at 26 reaches of a permanent irrigation channel in September and December 2007 and May 2008. The relative roles of niche versus dispersal processes were determined by examining species richness across the local environment, such as habitat complexity (diversity of depth and velocity) and size (volume of water) or proximity from the river as potential source of species, and deterministic versus stochastic processes. Non-random or random patterns of species co-occurrence were also compared across the sites., Each site's species richness was mainly associated with habitat complexity and size, but not proximity to the river. Also, species co-occurred non-randomly in segregated patterns. Therefore, the fish community was deterministically structured by niche processes and local extinction, but not by stochastic and external immigration processes. In addition, the observed relative abundance distributions primarily fitted a log-normal distribution, indicating a 'low stress' condition for the fish community., To enhance co-existence of fish species, high conservation priority should be given to local factors such as hydraulic complexity and volume of water at reach scale in the rice irrigation system. Fish species preferring slow and shallow environments co-occurred less frequently among reaches, demonstrating the need to conserving hydraulic variability. The effectiveness of local factors and deterministic patterns is thought to derive from stable water flow and high internal and external connectivity, which in turn would safeguard the processes that structure fish community assemblages. Such hydrological connectivity might be the key for conservation in intensified rice-farming landscapes., Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Understanding the mechanism governing the movements of stream-dwelling fish is a fundamental issue associated with a diverse range of ecological processes. We examined the movement pattern of a small benthic species, Lefua echigonia, using a mark-recapture technique in small headwater streams. Our main objectives were as follows: (i) to assess the movement range and direction of L. echigonia; (ii) to examine how biotic and abiotic factors affect emigration and immigration patterns and (iii) to assess movement patterns at the stream scale., Stationary fish accounted for the greatest proportion of recaptured adult L. echigonia. Seventy-five per cent of recaptured individuals moved <100 m in 12 months after release, and the maximum movement distance was 500 m upstream. Moreover, adult L. echigonia showed significant upstream bias in movements., According to the results of the generalised linear mixed model GLMM analysis, movement of adult L. echigonia was associated mainly with the density of conspecifics, rather than with habitat quality and body size. Adult L. echigonia were mainly stationary in relatively high-density sections, and emigration tended to increase with decreasing density. Moreover, mobile individuals were prone to move into relatively high-density sections., The proportion of mobile fish showed a strong positive correlation with catchment area at the stream scale. This result indicates that stream discharge can influence the mobility of adult L. echigonia. During baseflow, the water was static in a number of stream sections, which suggests that the influence of catchment area on mobility may be more a function of freshets than normal water flow. [ABSTRACT FROM AUTHOR]

Our objectives are to examine the influence of the difference in stress tolerance among species on patterns of nestedness and to test whether a set of several small ponds supports more species than a few large ponds of equal area. Although fish species assemblages for each group of all fish, tolerant and intolerant species were significantly nested, intolerant species showed stronger nested tendency than tolerant species, suggesting that the tolerance of species can influence the patterns of nestedness. These results suggest that the tolerance of species can influence the patterns of nestedness. As for the comparison of cumulative species richness in small ponds and large ponds, although small ponds supported more species for tolerant species, there was little difference for intolerant species. [ABSTRACT FROM AUTHOR]

The article discusses the management of the ponds within irrigation systems after the fish fauna have changed in Mount Iwate, Japan. It mentions that the ponds were monitored after the invasive piscivorous largemouth bass were eradicated. It states that species richness and diversity had increased in bass-eradicated ponds. It stresses the need for continuous monitoring and adaptive management of the ponds.