DOI: 10.5061/dryad.dfn2z35dw
title: Prolonged flow intermittency undermines the habitat potential of forested landscapes for a stream-dwelling dragonfly

description: Understanding how land use and variability of the hydrological regime
 jointly shape species distributions is essential for the conservation of
 aquatic insects in increasingly intermittent streams. We investigated how
 flow intermittency influences the relationship between land use and the
 occurrence probability of Cordulegaster heros in a drying river
 network. Field surveys were conducted at 42 stream sites in southwestern
 Hungary over a two-year period. We combined species presence–absence data
 with land use variables and hydrological proxies. Statistical analyses
 included decision tree modeling and binomial generalized linear
 models. C. heros was associated with forested landscapes and
 absent from sites with prolonged zero-flow periods or high agricultural
 land use. Occurrence probability declined markedly when forest cover was
 low or when dry periods were extended in duration. Although C.
 heros larvae can tolerate short-term drying by burrowing into sediments,
 prolonged flow intermittency and reduced landscape connectivity may limit
 both survival and recolonization. Our findings underscore the need for
 conservation strategies that jointly address land use and hydrological
 conditions to counter the rising flow intermittency expected with ongoing
 climate change.
description: # Prolonged flow intermittency undermines the habitat potential of
 forested landscapes for a stream-dwelling dragonfly Dataset DOI:
 [10.5061/dryad.dfn2z35dw](10.5061/dryad.dfn2z35dw) ## Description of the
 data and file structure ## Files : combined_df_merged_FIN5_xl.xlsx
 combined_df_merged_FIN5_tab.csv ### Descriptions of the files
 combined_df_merged_FIN5_xl.xlsx - an Excel dataset with a description of
 the variables combined_df_merged_FIN5_tab.csv - same tabular dataset ###
 Descriptions of the variables | name | description | variable description
 | unit | | ---------------------------------- | ------------------ |
 -------------------------------------------------- | --------------- | |
 SITE | code | SITE code | | | KM | code | SITE code numerical | | |
 PRESENCE | Biological | Presence of *Cordulegaster heros* | 1 True; 0
 False | | zeros | hydrological proxy | the total number of dry days | days
 | | long_zero_runs | hydrological proxy | the number of consecutive dry
 periods over 30 days | days | | longest_zero_runs | hydrological proxy |
 the longest consecutive dry periods in days | days | | zero_runs |
 hydrological proxy | the number of consecutive dry periods | days | |
 average_zero_runs | hydrological proxy | the average duration of dry
 periods in days | days | | mesterseges | land use | artificial |
 percentages | | agriculture | land use | agriculture | percentages | |
 gyep | land use | grassland | percentages | | forest | land use | forest |
 percentages | | bukk | land use | beech | percentages | | gyerty_kocs |
 land use | hornbeam-oak | percentages | | cser | land use | shrub |
 percentages | | TBVF_os | land use | riparian forest (softwood) |
 percentages | | elegyes | land use | mixed | percentages | | tulevelu |
 land use | coniferous | percentages | | akac | land use | black locust |
 percentages | | feluj | land use | regenerated | percentages | |
 nem_besorol | land use | unclassified | percentages | | oshonos | land use
 | native | percentages | | nem_oshonos | land use | non_native |
 percentages | | zavart_erdo | land use | disturbed_forest | percentages |
 | mesolithal | habitat | mesolithal | percentages | | microlithal |
 habitat | microlithal | percentages | | akal | habitat | akal
 (boulder–cobble substrate) | percentages | | psammal | habitat | psammal
 (sand substrate) | percentages | | argyllal | habitat | argyllal (clay
 substrate) | percentages | | xylal | habitat | xylal (wood substrate) |
 percentages | | CPOM | habitat | CPOM (coarse particulate organic matter)
 | percentages | | FPOM | habitat | FPOM (fine particulate organic matter)
 | percentages | | living parts of terrestrial plants | habitat | living
 parts of terrestrial plants | percentages | | slope | hydromorphology |
 slope | degrees | | elev | hydromorphology | elevation | m | | aspect_2 |
 hydromorphology | aspect_2 | degrees |