Especies y comunidades vegetales del lago Poyang, el lago de agua dulce más grande de China

Positive relationships among aboveground biomass, tree species diversity, and urban greening management in tropical coastal city of Haikou

Within urban green spaces, tree species diversity is believed to correlate with aboveground biomass, though there is some disagreement within the literature on the strength and directionality of the relationship. Therefore, we assessed the relationship between the biodiversity of woody species and the aboveground biomass of woody plant species in the tropical, coastal city of Haikou in southern China. To accomplish this, we obtained comprehensive tree and site data through field sampling of 190 urban functional units (UFUs, or work units) corresponding to six types of land uses governmental-institutional, industrial-commercial, park-recreational, residential, transport infrastructure, and undeveloped area. Based on our field data, we investigated the relationship between tree species diversity and aboveground biomass using multiple regression, which revealed significant relationships across all five types of land uses. Aboveground biomass in green spaces was also correlated with anthropogenic factors, especially time since urban development, or site age, annual maintenance frequency by human caretakers, and human population density. Among these factors, maintenance is the strongest predictor of aboveground biomass in urban green space. Therefore, this study highlights the critical role of maintenance of urban green space in promoting both aboveground biomass and woody biodiversity in urban ecosystems and, consequently, on urban ecosystem services. Our findings contribute to a deeper understanding of the ecosystem services provided by communities of woody plant species in urban areas.

Geochemical conditions of natural wetland and paddy fields in the Poyang Lake area, China

Abstract

During the last several decades, wetlands are losing their ecological functions due to increasing anthropogenic loads. One of these functions is the ability to bind elements forming geochemical barriers. The research aimed to study the geochemical conditions of natural wetlands and flooded paddy fields (artificial wetlands) in the Ganjiang River basin to trace geochemical barriers. The research approach was based on a comprehensive analysis of water and aqueous extracts from bottom sediments and paddy soils, including chemical and mineral composition. The samples were collected in November 2019, during the dry season at the end of harvesting. Chemical analysis was performed using standard methods for natural substances: titrimetry, photometry, ionic chromatography, high-temperature oxidation, ICP-MS, and ICP-AES. The mineral composition of the soils and sediments was determined by XRD. It was found that the main physicochemical characteristics (TDS, pH, main component concentrations) of the natural wetland water correspond to the surface water of the study area, whereas the irrigation water is similar to shallow groundwater. The content of trace elements in the irrigation water is higher than in the natural wetland water. Generally, the trace element composition of the natural wetland water corresponds to the geochemical background of the study area. Analysis of the mineral and chemical composition of the paddy soils and sediments indicates the geochemical barriers that accumulate a wide range of elements. In the natural wetland, the geochemical barrier is likely associated with a decrease in oxygen content and advective transport rate in the sediments, whereas in the paddy fields, the precipitation of clay minerals in the soil profile forms the geochemical barrier related to a decrease in filtration properties and advection–diffusion transport.

Graphic abstract

Número especial sobre <em>Ecología, evolución y conservación en las plantas de China</em>: introducción y algunas consideraciones

China tiene una de las floras más ricas del mundo con alrededor 33.000 plantas vasculares, de las cuales hasta 17.000 son endémicas. Además de estas cifras asombrosas, la flora china es muy interesante desde el punto de vista de la evolución, ya que muestra un fuerte carácter relictual con algunos auténticos «fósiles vivientes» como Ginkgo biloba o Metasequoia glyptostroboides. Al mismo tiempo, China probablemente alberga el «frente evolutivo» más importante de las floras templadas del mundo, las montañas Hengduan. Por desgracia, la flora de China también destaca por el elevado número de especies amenazadas (casi 4000), sobre todo debido a la destrucción de los hábitats y la sobreexplotación de los recursos naturales. Este número especial, que corresponde al volumen 34 de Collectanea Botanica, tiene como objetivo contribuir al conocimiento de la flora de China a través de una serie de contribuciones (siete artículos y una nota breve) que abarcan varios temas como la biogeografía, la conservación, la demografía, la ecología, la evolución y las interacciones planta-animal.