Dinámica de Phragmites australis y Schoenoplectus americanus en respuesta a la adición de fósforo y nitrógeno en humedales experimentales

Abstract

3Autora para la correspondencia: yazminelb@yahoo.com.mxResumen: Las especies invasoras, como Phragmites australis, resultan grandes competidoras para las especies nativas; sin embargo, es poco lo que se conoce sobre el mecanismo de invasión. En este trabajo se evaluó la interacción de P. australis con una especie nativa, Schoenoplectus americanus, mediante un experimento de parcelas divididas con adición de nutrimento (nitrógeno y fósforo). Para P. australis se encontraron diferencias (P < 0.05) entre tratamientos para la altura, el número de tallos y la biomasa aérea y de rizomas, mientras que para S. americanus se encontraron diferencias (P < 0.05) en la altura máxima, la altura promedio de tallos, el número de tallos, el porcentaje de cobertura y la biomasa aérea. El incremento de nutrimentos no permitió que P. australis desplazara a S. americanus, lo que sugiere que en condiciones naturales S. americanus será capaz de competir por los nutrimentos siempre y cuando no se presente algún disturbio, ya que en este estudio se mantuvo el dosel de especies nativas antes de introducir a P. australis. Los resultados sugieren que la competencia intraespecífi ca es más fuerte que la interespecífi ca en ausencia de disturbio. Palabras clave: competencia, composición, disturbio, diversidad, nutrimentos, restauración ecológica. Abstract:Invasive species, such as Phragmites australis, are major competitors for native species, however, very little is known about the mechanisms of invasion. In this study the interaction between P. australis with a native species, Schoenoplectus americanus, was evaluated through a split-plot experiment with addition of nutrients (nitrogen and phosphorus). For P. australis statistically signifi cant differences (P < 0.05) were found among treatments for height, number of stems, aboveground biomass and rhizomes, while for S. americanus, statistically signifi cant differences (P < 0.05) were found for maximum height, average height of stems and number of stems, percentage of coverage and aboveground biomass. The increase in nutrients did not allowed the displacement of S. americanus by P. australis. This result suggest that under natural conditions S. americanus could be able to compete for nutrients and not be displaced by P. australis, as longs as no disturbance occurs, because in this study the native species canopy was not altered before introducing P. australis. Our results suggest that intraspecifi c competition is stronger than interspecifi c in the absence of disturbance.

Facilitating the restoration of aquatic plant communities in a Ramsar wetland

“…Other studies have suggested that environmental factors likely to influence reed bed expansion include seasonal fluctuations in water levels and nutrient influxes from the lake bottom and surrounding river systems (Liira et al ; Catford et al ). However, based on the response of other wetland plants and other Schoenoplectus species to seasonal water fluctuations and nutrient increases (Escutia‐Lara & Lindig‐Cisneros ; Vivian et al ), it is likely that planted and remnant S. tabernaemontani stands would increase in size and extent if lake flows were more variable. A study by Catford et al () supports this fact, suggesting that hydrological regulation in the Murray River system limits the establishment of native plants adapted to variable flows while benefiting more invasive species.…”

“…Although S. tabernaemontani appears to be relatively resilient to drought conditions, having survived the Millennium Drought and subsequent low water levels by resprouting from rhizomes after normal water levels returned to Lake Alexandrina and Lake Albert (Nicol et al ), a variety of factors may influence the persistence of this species. These include nutrient increases (Escutia‐Lara & Lindig‐Cisneros ), droughts and subsequent wetland drying (Catford et al ) and access to the shoreline by livestock and livestock grazing (Vanderbosch & Galatowitsch ). Greater research into how factors such as climate variability, water levels, soil nutrients, and lake substrates influence the establishment of sedge species may increase our ability to more effectively restore important wetland systems.…”

Decrease in total hardness and amount of chlorides present in well water: influence of the aquatic plants of Phragmites australis and Lemna minor [Disminución de dureza total y cantidad de cloruros presentes en las aguas de pozos: influencia de las plantas acuáticas de Phragmites australis y Lemna minor]

“… Dilute it in 50 mL of distilled water and observe the turn.  3 to 4 drops of 5% K2CrO4 were added (Escutia, 2012).  Adjust the pH to a range of 6.3 -10.5, that is, if the sample is less than 6.3, make it alkaline with sodium carbonate (NaHCO3), but if it is greater than 10.5, add acetic acid (CH3COOH).…”

Diversity and Conservation Status of Mangrove Communities in Two Areas of Mesocaribea Biogeographic Region

“…habitat is being substituted by that of L. racemosa, whose habitat is in turn substituted by Conocarpus erectus, owing to reduction in depth of the lake basin, an increased inflow of freshwater, and a decrease in salinity. This horizontal dynamics is accompanied by an increase in the area occupied by Phragmites australis and Typha domingensis 22,23 , species whose optimal development occurs in sites with shallow standing water and low salinity, in contrast to the requirements for mangroves. Typical mangrove species are therefore being replaced by others from outside this type of community.…”