Unravelling the impact of anthropogenic pressure on plant communities in Mediterranean temporary ponds

Abstract

Identifying the respective role of environmental, landscape and management factors in explaining the patterns in community composition is an important goal in ecology. Using a set of 32 temporary ponds in northern Morocco we studied the respective importance of local (within the pond) and regional (density of ponds in landscape) factors and the impacts of different land uses on the plant species assemblages, separating pond and terrestrial species. The main hypotheses tested were that (1) species assemblages respond to both local and regional environmental factors, (2) anthropogenic pressure has a negative influence on the number of pond species, and that (3) human activities differ in their impact on pond biodiversity. The results showed that (1) local factors explain most of the variation in plant community composition, and (2) land use impacts the communities through changing local environmental conditions, leading to a loss of typical pond species. Aside from recreation, all other activities (grazing, drainage, agriculture and partial urbanisation) significantly reduced the number of pond species. The conservation strategy for rare pond species should focus on maintaining networks of oligotrophic ponds, while allowing only low-impact activities.

Livestock disturbances in Mediterranean temporary ponds: A mesocosm experiment with sheep manure and simulated trampling

“…This sediment was taken from two sets of three ponds on 4 December 2013 in each of an agricultural and a forested area. The ponds were selected based on the high species richness of their propagule bank (forest propagule richness = 46, 52, and 54 species and agricultural propagule richness = 50, 43, and 37 species; Bouahim et al, 2014;El Madihi et al, 2017;Rhazi et al, 2001). From each pond, 2 m² (1 m² of the peripheral zone and 1 m² of the centre) of the upper 3 cm of sediment containing the active seed (Rhazi et al, 2001) and egg bank (Brendonck & De Meester, 2003) were collected.…”

“…Grazing effects are expected to be more intense in aquatic habitat than the surrounding vegetation matrix. This can occur because livestock herds often gather around the littoral zone to drink (Foote & Hornung, 2005;James, Kleinman, Veith, Stedman, & Sharpley, 2007), or enter the wetland to graze, and because many sensitive and rare plant species are found in the wetland basin (Barbour et al, 2007;Bouahim et al, 2014;Rhazi et al, 2012). Therefore, some studies suggest that although grazing may be beneficial at landscape scale, it might be less favourable locally (Bouahim et al, 2010;Marty, 2005).…”

Assessing the ecological integrity of endorheic wetlands, with focus on Mediterranean temporary ponds

“…Similarly, in temporary ponds on both sides of the Strait of Gibraltar (Iberian Peninsula and Morocco), the plant community structure is related to nutrient loading, temperature and precipitation (Lumbreras et al, 2012). Lastly, the richness and abundance of rare and temporary pond specific species are a good indicator of chemical and physical disturbances in temporary ponds (Rhazi et al, 2001b;Bouahim et al, 2014). Rare and temporary pond specific species are not tolerant of disturbances, impacting negatively their richness and abundance.…”

“…Nevertheless, if detailed species identifications are required, we consider DNA barcoding as a potential tool to overcome identification difficulties, such as shown for example by Hajibabaei et al (2011) for benthic freshwater macroinvertebrates. Indices based on macrophytes are also highly relevant since temporary ponds often house characteristic highly specialized species (Bouahim et al, 2014) that play important roles in temporary wetland ecosystems (Bornette and Puijalon, 2011).…”

A history of discoveries and disappearances of the rare annual plant Lythrum thesioides M.Bieb.: new insights into its ecology and biology

“…Indeed, due to their small surface they are easily destroyed and have experienced a dramatic decrease in number and surface area around the Mediterranean region (e.g. Gallego-Fernández et al 1999;Rhazi et al 2012) due to agricultural intensification, pollution (including eutrophication), drainage and direct destruction for urbanization (Bouahim et al 2014).…”