Perspectives for ecological networks in plant ecology

Abstract

Background: Plant communities are usually characterised by species composition and abundance, but also underlie a multitude of complex interactions that we have only recently started unveiling. Yet, we are still far from understanding ecological and evolutionary processes shaping the network-level organisation of plant diversity, and to what extent these processes are specific to certain spatial scales or environments. Aims: Understanding the systemic mechanisms of plant-plant network assembly and their consequences for diversity patterns. Methods: We review recent methods and results of plant-plant networks. Results: We synthetize how plant-plant networks can help us to: (a) assess how competition and facilitation may balance each other through the network; (b) analyse the role of plantplant interactions beyond pairwise competition in structuring plant communities, and (c) forecast the ecological implications of complex species dependencies. We discuss pros and cons, assumptions and limitations of different approaches used for inferring plant-plant networks. Conclusions: We propose novel opportunities for advancing plant ecology by using ecological networks that encompass different ecological levels and spatio-temporal scales, and incorporate more biological information. Embracing networks of interactions among plants can shed new light on mechanisms driving evolution and ecosystem functioning, helping us to mitigate diversity loss.

An invasive plant species enhances biodiversity in overgrazed pastures but inhibits its recovery in protected areas

“…Three decades of biodiversity research suggest that more diverse ecosystems are more productive and may be more resilient to environmental perturbations through redundancy of functions carried out by different species (3,7). Furthermore, recent theoretical studies of plant networks predict that certain foundation species are critical for maintaining biodiversity as they increase community robustness (15,29). Yet, despite these advances, our understanding of the ways in which biodiversity concurrently contributes to the ability of ecosystems to recover functioning after prolonged exposure to multiple anthropogenic stressors remains far from complete.…”

“…In the face of anthropogenic environmental change, ecosystem resilience can be strongly influenced by changes in biodiversity and ecosystem functioning that arise from the interaction of multiple stressors acting across different spatial and temporal scales (3,10,15). For instance, local-scale perturbations such as fire exacerbate the negative effects of large-scale deforestation (12).…”

“…Contrary to previous claims regarding the positive effects of livestock grazing on biodiversity (16,20) but consistent with current evidence on the impact of such land-use practice (4,9,12), our experiment documented detrimental impacts of overgrazing on plant communities. Livestock grazing erodes biodiversity by favoring a few dominant species(15,23,24) and triggering invasion by unpalatable plants that ultimately limit the ability of communities to recover. Consequently, we foresee that effective management measures to improve ecosystem resilience in this and similar systems will need to include both the reduction of grazing pressure and exclusion of the invasive species.…”

Co-occurrence frequency in vegetation patches decreases towards the harsh edge along an arid volcanic elevational gradient

“…In other words, patchy vegetation cover might reflect patchy environmental suitability, facilitative biotic interactions or a combination of both. Additionally, species tend to interact in complex networks rather than pairwise combinations, which results in indirect effects among plants through diffuse or intransitive interactions (Losapio et al 2019). Furthermore, patterns of biotic interactions may change over time, with a changing hierarchy of resource ratios, changing stoichiometric requirements of individual species and thus of limiting factors, as suggested by the theory of pulse dynamics and disturbance in ecology (Jentsch and White 2019).…”

Uncovering structural features that underlie coexistence in an invaded woody plant community with interaction networks at multiple life stages

“…Network theory provides a set of tools to analyse and quantify the structure and dynamics of complex systems with many interacting parts, and plant communities can be represented as networks in which species are linked by competitive and facilitative interactions. With plant interaction networks, it is possible to explore potential mechanisms driving community dynamics and local diversity by quantifying emergent properties that cannot be determined by metrics like species richness or comparisons of pairwise species interactions (Kinlock, 2019; Losapio, Montesinos‐Navarro, & Saiz, 2019; Losapio & Schöb, 2017; Saiz, Gómez‐Gardeñes, Borda, & Maestre, 2018). Networks are composed of smaller substructures, which are the interactions among species subsets in the network (Milo et al., 2002).…”