Water depletion drives plant succession in farm ponds and overrides a legacy of continuous anthropogenic disturbance

Abstract

Questions Abandonment of anthropogenic ecosystems threatens biodiversity in rural areas globally. Successional responses in anthropogenic ecosystems have been shown to differ from those in natural ecosystems because of the legacy of continuous management activities. However, few studies have focused on successional changes in anthropogenic freshwater ecosystems following abandonment. Focusing on two drivers (water depletion and cessation of anthropogenic disturbance), we tested whether water depletion plays a larger role than years since abandonment in determining the both plant functional diversity and composition in farm ponds. Location Awaji Island, western Japan. Methods We investigated flora at 200 farm ponds, which had experienced long‐term continuous anthropogenic disturbance. We interviewed 100 managers of the surveyed ponds and local farmers to identify the ponds’ management status. To capture community processes during succession, we focused on functional richness and functional trait composition. We assessed the relative contribution of the two successional drivers in determining functional richness by adopting a linear model. We classified the survey ponds into five groups based on the two successional drivers and performed PERMANOVA to test differences in functional composition among the groups. Results Water depletion played a larger role than elapsed time since cessation of anthropogenic disturbance in determining functional richness. Functional composition of water‐depleted ponds significantly differed from that of managed ponds, regardless of years since abandonment. Conclusions Our results indicate that water depletion has a larger effect on successional changes in ponds than cessation of anthropogenic disturbance; that is, water depletion drives succession and overrides the legacy of continuous anthropogenic disturbance. The results suggest that, in freshwater ecosystems, the functional change in a community is greater in the transition from macrophytes to terrestrial plants than it is in the transition from stress‐tolerant species to competitive species.

Linking vegetation patterns, wetlands conservation, and ecosystem services provision: From publication to application

“…Drying events, however, can also trigger negative successional dynamics, favouring the entry and establishment of terrestrial and ruderal plants into wetlands. At the same time, differentiated hydroperiods may expand the niches available for colonization by aquatic and wetland taxa (Brose, 2001; Toyama & Akasaka, 2017). These conflicting findings suggest the existence of complex, often hidden, interactions between physical and biotic factors in inland aquatic ecosystems, and call for further research attention.…”

Managing farm ponds as breeding sites for amphibians: key trade‐offs in agricultural function and habitat conservation

“…). Similarly, in many agricultural regions of Japan (see Toyama and Akasaka ) and Europe (see Curado et al. and Hartel and von Wehrden ), ponds have fallen into disuse due to rural land abandonment, and management would focus on preventing dominance of late‐successional ponds.…”

Associations between Macrophyte Life Forms and Environmental and Morphometric Factors in a Large Sub-tropical Floodplain

“…Because macrophytes are important components of aquatic ecosystems in terms of biomass production and habitat structuring and present particularities regarding the responses of life forms to environmental factors, understanding the relationships between life forms and environmental and morphometric factors might provide the stepping stone to improving the knowledge of ecosystem processes. However, most of the investigations in aquatic ecosystems using a functional approach have focused on the drivers of richness and composition of macrophyte life forms (Akasaka et al, 2010 ; Akasaka and Takamura, 2011 ; Netten et al, 2011 ; Alahuhta and Heino, 2013 ; Alahuhta et al, 2013a ; Alahuhta, 2015 ; Morandeira and Kandus, 2016 ; Toyama and Akasaka, 2017 , among others), but research on the relationship between the biomass (or primary productivity) of particular life forms and the changes in environmental factors is still scarce (Sand-Jensen and Sondergaard, 1979 ; Lampert and Sommer, 1997 ; Hudon et al, 2000 ; Stromberg and Merritt, 2015 ). Because the mechanisms by which diversity is expected to affect ecosystem functioning depend on the functional characteristics of local communities, assessing the relative importance of the abiotic variables to the biomass of particular life forms and to the life forms composition of the assemblages is key for comprehending the structure and dynamics of ecosystems.…”