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Biodiversity and recovery of forest in tropical landscapes

Periodic Reporting for period 1 - PANTROP (Biodiversity and recovery of forest in tropical landscapes)

Reporting period: 2019-09-01 to 2021-02-28

The challenge- Tropical forests are global hotspots of biodiversity, play key roles in the global carbon and water cycle and deliver crucial ecosystem services but are threatened by human-induced climate change, deforestation and biodiversity loss. I focus on forests that regrow after complete forest removal for agriculture (secondary forests), because they cover large areas, have great potential to recover biodiversity and carbon, and are the basis for ecosystem restoration. The key challenge is to understand and predict forest resilience: when, and under what conditions are regrowing forests able to recover and have the same quality and functioning as old-growth forests?

Aims- This study aims to understand and predict the resilience of tropical forests to human-driven disturbance by analyzing the effects of (1) continent and biogeography, (2) climate, (3) landscape, and (4) biodiversity on forest recovery rate.

Approach- We will use a pantropical approach by synthesizing current data and doing controlled experiments on three continents (Neotropics, Africa, and Australia) in climatically contrasting forest types (dry and wet forest). We will (1) assess long-term recovery of multiple facets of tropical forests after agricultural use, by expanding a unique Neotropical network of 60 sites to the pantropics, (2) analyse the role of the landscape (i.e. the spatial distribution of remaining forest patches and trees) on forest recovery by doing a natural experiment along forest cover gradients, (3) understand how different kinds of diversity, such as dominant species and rare species, affect succession and ecosystem functioning through a biodiversity removal experiment.

Impact- This study addresses key questions in ecology and advances our understanding how human-driven climate change, landscape degradation, and biodiversity loss affect forest resilience and succession. The insights can be applied to (1) reduce human impacts on tropical forests, (2) design resilient and multifunctional tropical landscapes, and (3) design effective forest restoration strategies.
Background. PANTROP aims to understand and predict the resilience of tropical forests to human-driven disturbance. It uses a pantropical approach by synthesizing current data (S1) and doing controlled experiments in Mexico, Ghana, and Australia (S2, S3).

General. A kickstart workshop was held in Mexico (Nov. 2019) with the whole team to sharpen the project aims. Staff has been contracted and the protocols for the field studies have been finalized. Teams consisting of the PI, PhD student and local collaborator have visited each country and identified fieldsites for plots. Fieldwork started in Nov 2019-Mar 2020 but was interrupted in March because of Covid, when staff had to return to the Netherlands for safety reasons. This has caused a 1-year delay.

S1 Pantropical. This study compares forest recovery across continents by synthesizing chronosequence data. We have expanded the database from 50 Latin American sites to 78 sites, including 9 in West Africa, and a new PANTROP-funded chronosequence in Ghana. We synthesized the current knowledge on how previous land use affects forest regrowth (Jakovac et al 2021 Biological Reviews). We provide an overview of the mechanisms underlying forest regrowth and propose a framework to support the design of forest restoration actions.

S2 Landscape & S3 Diversity. These field experiments analyze how forest recovery is affected by landscape forest cover (FC) and biodiversity (BD). Fieldwork was interrupted and delayed because of Covid. In Mexico we have established all 34 FC plots and 15 BD plots. In Ghana we have identified all areas and have restarted fieldwork, when safety regulations permitted, in January 2021. We now have laid out (i.e. demarcated and gridded) 28 FC plots and 10 BD plots, but only 2 FC plots have been measured. At this moment, hydraulic traits are being measured. In Australia we did not start because the strict safety regulations did not allow.
This study addresses key questions in ecology and advances our understanding how human-driven climate change, landscape degradation, and biodiversity loss affect forest resilience and succession. The insights can be applied to (1) reduce human impacts on tropical forests, (2) design resilient and multifunctional tropical landscapes, and (3) design effective forest restoration strategies.
Fieldsite Mexico: Dry forest region of Nizanda, with pastures and forests
Fieldsite Australia: Atherton Tablelands with dairy farms and rainforest remnants and corridors
Fieldsite Ghana: Dry forest region with shifting cultivation field and PhD student Jazz Kok