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

Abstract

Macrophyte assemblages are composed of species with different life forms and various ecological functions. Our aim was to investigate the potential environmental determinants of changes in the biomass of individual life forms and of the composition of the macrophyte assemblage in terms of life forms diversity. We sampled 23 waterbodies at low and high water levels in the Middle Paraná River floodplain. Macrophyte biomass samples were collected and classified in terms of life forms. We performed a redundancy analysis using the biomass of the various life forms to assess the importance of environmental variables to the composition of macrophyte life forms. Linear regressions were applied to investigate the environmental determinants of the biomasses of individual life forms. The degree of connectivity and the combination of depth, hydrology and nitrate were the main determinants of the composition in terms of life forms. The biomass of each individual life form was explained by different combinations of environmental variables, but the connectivity was the most important one. Our study shows that groups of species with similar life forms respond to environmental factors in particular ways, which might alter the biomass composition of life forms. Given that the ecosystem functioning depends on the functional characteristics of local communities, our findings about the relation between environmental changes and the community composition in terms of life forms (or functional composition) can be a helpful tool for predicting changes on ecosystem processes (such as nutrient cycling) against possible future scenarios.

Climate Vulnerability Assessment of the Espeletia Complex on Páramo Sky Islands in the Northern Andes

“…Despite it has a relatively small surface area (35,000 km 2 ), it contains over 3,000 plant species, several of which are endemic (Luteyn, 1999;Hughes and Atchison, 2015) and emerged as unique adaptations to extreme environments that evolved during the Andean uplift in the last five million years (Antonelli et al, 2009;Madriñán et al, 2013;Mutke et al, 2014). Unparalleled diversification rates across plant groups at these tropical "sky islands" (Sklenáø et al, 2014) has further been attributed to colonization by pre-adapted linages (Muellner-Riehl, 2019), and Pleistocene glacial cycling (Nevado et al, 2018;Perrigo et al, 2019;Rahbek et al, 2019) in the last 2.4 Myr that led to repeated periods of connectivity and spatial isolation (i.e., "species pump hypothesis"). Population fluctuations in concert with past glacial cycling indicate a general inability to adapt and a major role of range shifts (Martín-Bravo et al, 2010;Ronikier, 2011;Hazzi et al, 2018;Muellner-Riehl, 2019).…”

“…Unparalleled diversification rates across plant groups at these tropical "sky islands" (Sklenáø et al, 2014) has further been attributed to colonization by pre-adapted linages (Muellner-Riehl, 2019), and Pleistocene glacial cycling (Nevado et al, 2018;Perrigo et al, 2019;Rahbek et al, 2019) in the last 2.4 Myr that led to repeated periods of connectivity and spatial isolation (i.e., "species pump hypothesis"). Population fluctuations in concert with past glacial cycling indicate a general inability to adapt and a major role of range shifts (Martín-Bravo et al, 2010;Ronikier, 2011;Hazzi et al, 2018;Muellner-Riehl, 2019). Yet, it remains to be explored whether the rapidly evolving Páramo can keep pace with the quick rate of climate change and human expansion.…”

Same species, same habitat preferences? The distribution of aquatic plants is not explained by the same predictors in lakes and streams

“…Overall, the different life forms of aquatic plants often exhibit variable responses to environmental factors (Netten, Zuidam, Kosten, & Peeters, ; Xia, Yu, Wang, & Xie, ), due to their specific morphological characteristics and their position in the water column. For example, free‐floating species are strongly dependent on nutrient availability in the water column (Schneider, Cunha, Marchese, & Thomaz, ), while floating‐leaved, submerged and helophyte species can obtain nutrients from sediments (Barko & Smart, ). However, the growth and survival of submerged species are dependent on under‐water light availability, while the three other functional life forms have morphological primacy to obtain this resource.…”

Variation in species assemblages due to micro-topography and flow regime govern vegetation carbon stock in seasonal floodplain wetlands

“…Habitat heterogeneity created due to varying topographic and hydrologic characteristics generally determine the growth and distribution of aquatic vegetation (Ward et al 1999;Bendix and Hupp 2000;Van Der Valk 2005;Camporeale and Ridolfi 2006). Such variations facilitate the plant species to colonize, co-exist, and proliferate (Dahlberg 2016;Larkin 2016;Schneider et al 2018). This is evident in our study, where varying environmental condition putatively resulted in differential species assemblage pattern.…”