Plants for nitrogen management in riparian zones: A proposed trait‐based framework to select effective species

Assessment of water and sediment quality in intermittent streams across different land uses in the Brazilian semiarid region: implications for sustainable irrigation and resource management

Water scarcity is a critical global issue, especially in semiarid regions where limited water resources are increasingly pressured by socioeconomic vulnerabilities and agricultural demands. In this study, we evaluated the quality of water and sediment from intermittent streams in a watershed located in Brazil's semiarid northeastern region, assessing their suitability for irrigation while considering the influence of different land uses. Based on the Brazilian Environmental Council classification, we found that 82% of the sampled sites were categorized as freshwater, indicating general suitability for irrigation. However, the hydrochemical and sediment analyses revealed significant anthropogenic impacts, particularly at agricultural and urban sites, where higher levels of salinity, nutrients, heavy metals, and other pollutants were observed. Moderate salinization risks were noted at 70% of the sites, primarily linked to anthropogenic land-use practices, with total dissolved solids, chlorides, and bicarbonates emerging as key indicators of degradation. Riparian forests demonstrated a notable buffering effect, reducing salinity and nutrient levels, although elevated concentrations of manganese and iron were also detected, likely due to natural geochemical mobilization and upstream contamination. These results highlight the critical role of riparian vegetation in mitigating environmental impacts and emphasize the need for targeted soil and water management strategies, such as crop selection, irrigation practices, and land-use planning. By addressing the combined effects of land use and natural pressures on water quality, we provide essential insights for sustainable irrigation and resource management in semiarid regions, supporting both agricultural productivity and ecological preservation.

Plant Species Complementarity in Low-Fertility Degraded Soil

The aim of this study was to investigate the compatibility of plants with contrasting root systems, in terms of procurement of limiting soil nutrients. Paired combinations of species of proteas and grasses were grown in a pot experiment using soil from a site with impoverished vegetation and degraded soil. The soil contained sufficient N but was low to deficient in P, Mn, S, Fe, and B. The uptake of chemical elements into the foliage differed significantly according to whether the plants were growing as single or mixed species. When two species of Grevillea and grasses with evolutionary origins in low fertility soils were growing together, there was an enhanced uptake of P and Mn, in one or both species, in addition to other elements that were in low concentrations in the experimental soil. In contrast to this, Protea neriifolia that probably originated from a more fertile soil procured lesser amounts of the six elements from the soil when growing together with grasses. Two grasses tolerant of less fertile soils (Dactylis glomerata and Poa cita) obtained more nutrients when they grew together with proteas; this was a much stronger neighbour effect than was measured in Lolium perenne which is better adapted to high fertility soils. The findings illustrate both the functional compatibility and competition for plant nutrients in mixed-species rhizospheres. Species combinations substantially increased the acquisition of key elements from the soil nutrient pool.

Tree Advisor: A Novel Woody Plant Selection Tool to Support Multifunctional Objectives

Purposefully planted trees and shrubs can provide multiple benefits when appropriately planned and designed. Tools to help select species that will function more effectively than other species for ecosystem services, production, and aesthetic purposes are generally lacking. To address this challenge, we developed an interactive plant selection tool entitled Tree Advisor that rates woody species for a wide range of different purposes based on plant attributes. In this prototype decision support tool, 90 species of trees and shrubs are rated for 14 different purposes in the northern and central Great Plains region of the United States. A rating algorithm was developed based on the scientific literature regarding plant functions and related attributes that determine relative performance of a species for each purpose. User input and best practices for developing effective decision support tools informed the tool development process. Based on user feedback, the tool supports multifunctional planning and enables a user to quickly develop a short list of the better species to use which can then be refined by the user based on suitability under local site conditions, commercial availability, and availability of locally adapted cultivars and hybrids. This tool development approach can serve as a model for producing multifunctional woody plant selection tools for other ecoregions.

Responses of different facets of aquatic plant diversity along environmental gradients in Mediterranean streams: Results from rivers of Greece

Aquatic and riparian plants play a crucial role in the functioning of riverine ecosystems. Hence, analyzing multiple facets of plant diversity could be extremely useful for assessing the ecological integrity of lotic ecosystems. The main objective of this study was to investigate the response of multiple facets of aquatic plant diversity, such as species richness, taxonomic distinctness and compositional dissimilarity, to environmental factors (i.e. nutrient pollution and hydromorphological alteration) in 72 stream reaches of mainland Greece. We employed Generalized Additive Models to identify the variables with the highest influence and examine the response of species richness and taxonomic distinctness to environmental gradients. The relationship between compositional dissimilarity and the environment was examined with Generalized Dissimilarity Modelling. Our results supported our hypothesis that human disturbances play a considerable role in shaping macrophyte assemblages. In particular, phosphates and hydromorphological modification were significant predictors of species richness, whereas taxonomic distinctness was unaffected by indicators of anthropogenic stress but it was influenced mostly by elevation, water temperature and pH. Concerning the compositional dissimilarity, geographic distance, elevation, temperature and total inorganic nitrogen were the most important environmental parameters. Our findings suggest that human stressors, such as hydromorphological modification and nutrient enrichment, affect the plant species richness at stream reach scale, but when considering community composition or taxonomic distinctness, environmental factors associated with the natural variability (e.g. elevation, temperature and geographic distance) are of higher importance. Overall, our results emphasize the advantage of examining multiple aspects of diversity when designing conservation schemes and management plans for riparian areas.

Co-association of Two nir Denitrifiers Under the Influence of Emergent Macrophytes

Diverse microorganisms perform similar metabolic process in biogeochemical cycles, whereas they are found of highly genomic differentiation. Biotic interactions should be considered in any community survey of these functional groups, as they contribute to community assembly and ultimately alter ecosystem properties. Current knowledge has mainly been achieved based on functional community characterized by a single gene using co-occurrence network analysis. Biotic interactions between functionally equivalent microorganisms, however, have received much less attention. Herein, we propose the nirK- and nirS-type denitrifier communities represented by these two nitrite reductase (nir)-encoding genes, as model communities to investigate the potential interactions of two nir denitrifiers. We evaluated co-occurrence patterns and co-association network structures of nir denitrifier community from an emergent macrophyte-dominated riparian zone of highly active denitrification in Lake Taihu, China. We found a more segregated pattern in combined nir communities than in individual communities. Network analyses revealed a modularized structure of associating nir denitrifiers. An increased proportion of negative associations among combined communities relative to those of individual communities indicated potential interspecific competition between nirK and nirS denitrifiers. pH and NH₄⁺-N were the most important factors driving co-occurrence and mutual exclusion between nirK and nirS denitrifiers. We also showed the topological importance of nirK denitrifiers acting as module hubs for constructing entire association networks. We revealed previously unexplored co-association relationships between nirK and nirS denitrifiers, which were previously neglected in network analyses of individual communities. Using nir denitrifier community as a model, these findings would be helpful for us to understand the biotic interactions and mechanisms underlying how functional groups co-exist in performing biogeochemical cycles.

Principal Threats to the Conservation of Running Water Habitats in the Continental Biogeographical Region of Central Europe

This paper discusses the threats to the running water habitats that are highly important to biodiversity the European Community in the Continental Biogeographical Region (CBR) of Europe, specifically in Poland. This study covers four water course habitat types distinguished in Natura 2000, which is a network of nature protection areas in the territory (3260, 3220, 3240, 3270 - the code of the habitat, as in Annex I of the Habitat Directive), occurring in 806 Special Areas of Conservation in Poland. Based on a multivariate analysis, we found significant differences in the conservation status of running water habitats resulting from a variety of threats, pressures, and activities. Agriculture has a number of negative impacts on running water habitats, which are most evident for the following habitats: 3260 > 3270. Forest management may have both negative (3260) and positive effects on habitats (3270). Natural system modifications strongly affect habitats 3240, 3270 > 3260. Among the negative anthropogenic influences are pollution (3260 > 3220); human intrusions, disturbances, and tourism (reported most often) (3260, 3270); transportation and service corridors (3260, and 3270); urbanization, residential, and commercial development tourism (3260); biological resource use other than for agriculture and forestry (3270 > 3260); and mining, extraction of materials, and energy production (3270). Geological events and natural catastrophes—most often inundation—were identified as important hazards for habitat 3240. The development of alien and invasive species strongly affects habitats 3240 > 3260, 3270, and natural biotic and abiotic processes affect habitats 3220 > 3260. Negative impacts associated with climate change were detected mostly for habitat 3260. Taking into account the threats identified, a list of recommended practices for running water habitat types is presented, to be considered in habitat conservation programmes.