Forest restoration has long been seen as a fruitful policy for preserving biodiversity and the myriad of ecosystems that exist on our planet. However, its success may be modulated by different climate conditions around the world. As temperatures and precipitation become increasingly variable, the effectiveness of this strategy may be subject to the whims and fancies of climate change, according to a recent study.

One goal aims to restore 350 million hectares of forests by 2030 as a means of mitigating climate change. But the impact of global forest restoration efforts has remained unclear, especially across diverse ecosystems.

Guiyao Zhou, a researcher at East China Normal University, in China, and his colleagues compiled data from 120 studies on forests across five continents, various ecosystems, and climate types. They explored the impact of planting forests in different environments on the planet.

“In this study, we found that forest restoration promoted multiple dimensions of biodiversity and ecosystem function such as soil fertility, plant biomass, microbial habitat, and carbon sequestration across contrasting climates and forest types,” wrote Zhou, in an email. “More importantly, our findings also indicate that climate will constrain the positive effects of forest rewilding on biodiversity and ecosystem function.”

It was found that forest restoration improved several aspects of biodiversity and ecosystem function, including plant biomass, soil fertility, microbial habitat, and carbon stocks, even across varying climes. But the climate in a region influenced the efficacy of forest restoration, with some conditions strengthening the positives and others diminishing them.

The researchers found that both precipitation and temperature constrained the impact of forest restoration. For instance, dryer ecosystems had lower average changes in plant biomass but greater changes in soil fertility due to forest restoration. Moreover, higher annual temperatures in warmer regions were linked to lower levels of carbon sequestration in the soil.

The virtues of restoration are therefore contingent on the climate of a specific ecosystem. As climate patterns grow more variable, the influence of temperature and precipitation on restoration efforts may grow stronger. With the planet growing hotter and drier, the benefits of planting more forests may weaken over time. “Ongoing climate change may deeply dampen the positive effects of forest restoration on ecosystem functions and biodiversity,” wrote Zhou.

Rainfall patterns had more influence than temperature on forest restoration with 86% of ecosystem functions affected. Despite the dampening impact of the changing climate on the advantages of forest restoration, it may yet have the potential to ameliorate these negatives and greatly amplify carbon stocks in the soil.

Ancient forests may warrant greater care and attention for restoration efforts to pay off. This is because Zhou and his colleague observed a surprising disconnect between biodiversity and ecosystem function. While the two have always been inextricably linked, this was not the case for old forests. Surprisingly, the two were negatively coupled in very old forests, with benefits from restoration paying off for one or the other. In old forests, selective, active management may be needed to maintain the healthy functioning of ecosystems.

“Our study provides new insights on the impacts of climate in the restoration of forest ecosystems based on the current literature,” wrote Zhou. “Yet, future work should aim to continue providing new insights and monitoring the restoration of these ecosystems, especially for those ecosystem properties and environments for which less information is available.”

In the future, the researchers hope to study the interactions and possible tradeoffs between ecological diversity and its function in Mediterranean forests that are being restored.

Reference: Guiyao Zhou, et al., Temperature and Rainfall Patterns Constrain the Multidimensional Rewilding of Global Forests, Advanced Science (2022). DOI: 10.1002/advs.202201144

Feature image credit: Olena Sergienko on Unsplash