A global meta‐analysis of the impacts of tree plantations on biodiversity

Abstract

Aim Planted forests are becoming increasingly common world‐wide for a variety of reasons, including water conservation and carbon sequestration, although the effects of tree plantations on biodiversity are unclear with respect to whether planted ecosystems are “green deserts” or valuable habitats for biodiversity. Location Global. Time period 1980–2020. Taxa studied Flora, fauna and microorganisms. Methods By conducting a meta‐analysis of 361 observations from 138 sites world‐wide, we explored the global patterns and associated drivers of biodiversity responding to tree plantations by comparing biodiversity levels in plantations and adjacent habitats (primary or secondary forests). Results Overall, the biodiversity (species richness) and abundance across multitrophic levels in tree plantations were lower than those in primary forests, reached similar values to secondary succession, but varied with plantation and management regimes. Specifically, the biodiversity across multitrophic levels in reforestation was higher than that in afforestation; the biodiversity in mixed, native species and unmanaged plantations was higher than that in monoculture, exotic species and managed plantations. The diversity of vertebrates, invertebrates and plants in reforestation was lower than that in primary forests, whereas belowground biodiversity in reforestation showed no difference from primary forests. Invertebrate diversity in reforestation was lower than that in secondary succession, whereas plant diversity was higher than that in secondary succession. Moreover, the biodiversity in reforestation increased with reforestation age. Furthermore, structural equation models showed that aboveground faunal diversity in reforestation was driven by canopy coverage and plant diversity and that reforestation affected belowground biodiversity mainly by changing soil organic carbon. Main conclusions Our findings suggest that reforestation by planting mixed native species will be more beneficial to biodiversity. We reveal that biodiversity in intensively managed plantations is significantly lower than that in restoration‐oriented plantations. We highlight that primary forests are not replaceable, but that planted forests might be a reliable way to restore biodiversity rapidly.

Temporal Soundscape Patterns in a Panamanian Tree Diversity Experiment: Polycultures Show an Increase in High Frequency Cover

“…Birds in contrast are likely to be more mobile and their home ranges might not be restricted to a single plot. A recent meta-analysis revealed that bird diversity in plantations is lower than in natural forests but that overall faunal diversity, including birds, benefits from planting a mix of native tree species (Bohada-Murillo et al, 2020;Wang et al, 2021) An increase in tree species richness could increase orthopteran abundance and diversity via an improved variety of food sources, especially for specialist plant consumers. A mechanism that is modulated by trophic interactions, as was shown for grassland ecosystems (Siemann, 1998;Ebeling et al, 2018).…”

“…Another mechanism could be the indirect effect of tree species richness on microclimate and microhabitats. In a global metaanalysis, canopy cover, which affects microclimate, was the most important driver of faunal biodiversity (Wang et al, 2021). How microclimate can change the acoustic communities was addressed by Campos-Cerqueira et al (2020) and Burivalova et al (2021).…”

Assisted restoration interventions drive functional recovery of tropical wet forest tree communities

“…In cases where natural recovery is slow, rapidly increasing canopy cover by planting trees can shade out invasive forage grasses, attract dispersers, and ameliorate microclimatic conditions for seedling establishment (Lamb, 2005;Holl, 2012). Moreover, a recent global meta-analysis demonstrates that native tree plantations can speed the recovery of plant species richness when compared to natural recovery (Wang et al, 2021), and intermediate levels of assisted recovery, such as applied nucleation, can recover tree species richness and composition to levels observed when using more resource-intensive plantation approaches (Holl et al, 2017(Holl et al, , 2020. However, patterns of plant diversity and structure recovery only tell part of the story.…”

Integrating carbon stocks and wildlife connectivity for nature-based climate solutions

“…Ecosystem restoration is an important part of the solution; however, it should not be seen as a silver-bullet (Holl & Brancalion, 2020). While restoration efforts (e.g., reforestation of mixed, native forests) provide meaningful biodiversity benefits (Wang, Zhang, Li, & Wu, 2021) and increase carbon sequestration and storage (Lewis, Wheeler, Mitchard, & Koch, 2019), proactively conserving large intact ecosystems with high ecological integrity should remain a focus (Cook-Patton et al, 2021; Grantham et al, 2020; Locke et al, 2019; Noon et al, 2021). Protection of intact ecosystems can be more cost effective than restoration of degraded habitats (Cook-Patton et al, 2021; Drever et al, 2021; Watson et al, 2018) and provide multiple, synergistic benefits by maintaining existing carbon sinks and preventing large, potentially irrecoverable carbon emissions while providing biodiversity benefits (Arneth et al, 2020; Proctor, Schuster, Buxton, & Bennett, 2022).…”