Daniel Bruno

Impacts of environmental filters on functional redundancy in riparian vegetation

1. Understanding and predicting ecosystem responses to multiple environmental pressures is a long-standing interest in ecology and environmental management. However, few studies have examined how t ...

Functional redundancy as a tool for bioassessment: A test using riparian vegetation.

There is an urgent need to track how natural systems are responding to global change in order to better guide management efforts. Traditionally, taxonomically based metrics have been used as indicators of ecosystem integrity and conservation status. However, functional approaches offer promising advantages that can improve bioassessment performance. In this study, we aim to test the applicability of functional redundancy (FR), a functional feature related to the stability, resistance and resilience of ecosystems, as a tool for bioassessment, looking at woody riparian communities in particular. We used linear mixed-effect models to investigate the response of FR and other traditional biomonitoring indices to natural (drought duration) and anthropogenic stress gradients (flow regulation and agriculture) in a Mediterranean basin. Such indices include species richness, a taxonomic index, and the Riparian Quality Index, which is an index of ecological status. Then, we explored the ability of FR and the other indices to discriminate between different intensities of human alteration. FR showed higher explanatory capacity in response to multiple stressors, although we found significant negative relationships between all the biological indices (taxonomic, functional and ecological quality) and stress gradients. In addition, FR was the most accurate index to discriminate among different categories of human alteration in both perennial and intermittent river reaches, which allowed us to set threshold values to identify undisturbed (reference condition), moderately disturbed and highly disturbed reaches in the two types of river. Using these thresholds and the best-fitting model, we generated a map of human impact on the functional redundancy of riparian communities for all the stretches of the river network. Our results demonstrate that FR presents clear advantages over traditional methods, which suggests that it should be part of the biomonitoring toolbox used for environmental management so as to obtain better predictions of ecosystem response to environmental changes.

Environmental determinants of woody and herbaceous riparian vegetation patterns in a semi-arid mediterranean basin

What environmental variables determine riparian vegetation patterns? Are there differences between woody and herbaceous species? To answer these questions, we first explored the composition and richness patterns of both riparian woody and herbaceous species in a semi-arid mediterranean basin. Then, we assessed the environmental factors (climate, geology, topography, hydrogeomorphology and land use) that best explain these patterns. We used the following methodological approaches: clustering analyses, distance-based linear models, generalised linear models and hierarchical partitioning procedures. Valley shape, drought duration, river habitat heterogeneity, water conductivity and agricultural land use were the most important variables explaining variation in species composition for both groups. Woody riparian richness was mainly influenced by flow conditions and valley shape, whereas herbaceous one was more dependent on substrate features. Thus, although some differences in the importance of individual variables were observed, we found a notable congruence in the composition and species richness of both groups and also in the main types of variables explaining these patterns (hydrogeomorphology and land use, especially agriculture). Our results show that both communities could be treated in a holistic way, since they respond similarly to the strong natural and anthropogenic environmental gradients present in mediterranean basins.

Respuestas estructurales y funcionales de las comunidades riparias mediterráneas a los filtros ambientales

Puerta-Pinero, A. 2016. Identification and evaluation of afforestations through the Spanish National Forest Inventory. Ecosistemas 25(3): 43-50. Doi.: 10.7818/ECOS.2016.25-3.05 Afforestation programs in Spain were performed mainly between 1930-1970 decades. The study of the state and functioning of these anthropogenic forests has a wide debate among scientists and stakeholders. Forest inventories represent a crucial source of data to evaluate the long-term functioning of these forests at broad spatial scales. This article shows several tools to identify and select plots from the third Spanish Forest Inventory composed by uniform afforestations. The functions intend to facilitate the work of scientists and technicians whose objective could be influenced by the presence or absence of these artificial forest type. Those functions are a first attempt to include or exclude plots that are composed by artificially afforested forests. I also present some preliminary results, and discuss strengths, weaknesses and future directions relative to the use of these functions.