Spatially designed revegetation—why the spatial arrangement of plants should be as important to revegetation as they are to natural systems

Abstract

The spatial arrangements of plants, both within and between species, play a key role in natural systems and influence many fundamental ecological processes (e.g. survival, competition, facilitation, pollination, and seed dispersal) and ecosystem functions (e.g. habitat value, erosion, water, and nutrient capture). Despite this knowledge, fine‐scale planting arrangements are rarely considered during restoration plantings, yet manipulation of planting designs has the potential to aid the development of resilient and self‐sustaining ecosystems. Here, we outline how the spatial arrangement of plants can influence processes both at the vegetation level and more broadly at the ecosystem level. The review is focused on woodland systems, but also draws on key examples from grassland ecosystems. Following this synthesis, we identify research gaps in the revegetation literature that could usefully be addressed to help develop this understudied field of research. Finally, we outline components of population and community level arrangements (e.g. spacing, aggregation, community composition) that can be considered during restoration plantings—spatially designed revegetation—which are likely to lead to improved ecological outcomes of woodland and grassy woodland revegetation.

Clumped planting arrangements improve seed production in a revegetated eucalypt woodland

“…Therefore, planting designs that mimic natural patterns of conspecific spacing and aggregation have the potential to facilitate pollinator movements between conspecifics increasing both the quantity and quality of seed produced. Although on‐going research is required, aggregated arrangements may also help maintain community level diversity, limit weed invasion, and improve habitat value in restored systems (McCallum et al ).…”

“…However, revegetation goals are often poorly defined, with success generally measured by the number of plants established or the total area planted, rather than ecological outcomes (Corr ; Wortley et al ; Thomas et al ). As a result, revegetation may create simplified plant communities (Bartha et al ), and concerns have been raised about the ability of these replanted systems to become self‐sustaining and resilient to environmental change (Ruiz‐Jaén & Aide ; McCallum et al ).…”

“…Restoring ecosystem functions (e.g. pollination, seed dispersal, nutrient cycling), is vital to create self‐sustaining revegetated populations (Miller et al ; McCallum et al ), and studies have shown that the spatial arrangement of plants may influence these functions. In natural systems, plants often display aggregated spatial patterns (Condit et al ; Perry et al ) due to environmental (e.g.…”

“…In some small or dispersed populations, regeneration may be limited by insufficient seed production, putting populations at risk of extinction (Lamont et al ). Species loss and subsequent declines in species diversity are risks if seed production and seed quality are limited in revegetated populations, but at this stage, the reproductive output of revegetated populations has rarely been assessed (McCallum et al ).…”

Plants, position and pollination: Planting arrangement and pollination limitation in a revegetated eucalypt woodland

“…It can be hypothesized that similar trends will occur in revegetated communities if planting activities create populations that are smaller and/or more spatially dispersed than those that occur naturally (McCallum et al . ). A study by McCallum et al .…”