Sammanfattning

The ongoing degradation of freshwater habitat quality and subsequent losses of biodiversity is alarming. One key to successful freshwater management is to understand how different scale-dependent diversity components (i.e. gamma-, alpha- and beta-diversity) change along present-day anthropogenic impact gradients. We used macrophyte, fish and macroinvertebrate data from Danish lowland streams to investigate whether (1) high connectivity in reaches situated in lower parts of the stream network (downstream sites) generates high alpha-diversity, while dispersal limitation and high habitat heterogeneity across the more isolated upper reaches (headwater sites) generate high beta-diversity, (2) gamma-, alpha- and beta- diversity decrease with increasing hydromorphological impact and (3) high connectivity in downstream reaches buffers against impacts on biodiversity. Results showed that alpha-diversity was higher in downstream sites, while headwaters did not exhibit greater beta-diversity. We observed a significant but relatively small decline in alpha-diversity with increasing hydromorphological impact, while beta-diversity changed more unpredictably along the gradient. There was no clear mitigating effect in downstream reaches as the reduction in diversity from low to high impacted sites was similar between upper and lower reaches. We suggest that the results, which generally contradicted our predictions, partly reflect the intense historic and present land use in the region leading to an isolation of available source communities and a diminished regional species pool. The importance of having a landscape perspective in conservation management in highly impacted regions is emphasised because it is a prerequisite for recolonisation and population stability over time.

Nyckelord

Macroinvertebrates; Fish; Macrophytes; alpha-Diversity; beta-Diversity; gamma-Diversity; Environmental stressors

Publicerad i

Biodiversity and Conservation
2015, Volym: 24, nummer: 6, sidor: 1423-1441
Utgivare: SPRINGER

SLU författare

• Sandin, Leonard

  • Institutionen för vatten och miljö, Sveriges lantbruksuniversitet
    

Associerade SLU-program

Sjöar och vattendrag
Använder FOMA data


Globala målen

SDG6 Säkerställa tillgången till och en hållbar förvaltning av vatten och sanitet för alla
SDG15 Skydda, återställa och främja ett hållbart nyttjande av landbaserade ekosystem, hållbart bruka skogar, bekämpa ökenspridning, hejda och vrida tillbaka markförstöringen samt hejda förlusten av biologisk mångfald


UKÄ forskningsämne

Miljövetenskap
Ekologi


Publikationens identifierare

DOI: https://doi.org/10.1007/s10531-015-0865-0

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/71176