Thread by @Dominic_Mart, New paper led by @Diversity_Turn MSc student @DomiSchwab out in @JAppliedEcology!Predation is [...]

New paper led by @Diversity_Turn MSc student @DomiSchwab out in @JAppliedEcology!

Predation is a key ecosystem function – but which factors influence predation rate and predator composition in #vanilla #agroforestry?

A thread about our findings

https://abs.twimg.com/emoji/v2/... draggable="false" alt="👇" title="Rückhand Zeigefinger nach unten" aria-label="Emoji: Rückhand Zeigefinger nach unten">

https://abs.twimg.com/emoji/v2/... draggable="false" alt="👇" title="Rückhand Zeigefinger nach unten" aria-label="Emoji: Rückhand Zeigefinger nach unten"> 1/15

New paper led by @Diversity_Turn MSc student @DomiSchwab out in @JAppliedEcology!Predation is a key ecosystem function – but which factors influence predation rate and predator composition in #vanilla #agroforestry?A thread about our findings https://abs.twimg.com/emoji/v2/... draggable=

In north-eastern #Madagascar

https://abs.twimg.com/emoji/v2/... draggable="false" alt="🇲🇬" title="Flagge von Madagaskar" aria-label="Emoji: Flagge von Madagaskar">, vanilla agroforests, rice paddies, land under shifting cultivation, forest fragments and old-growth forests form a diverse mosaic landscape. 2/15

In north-eastern #Madagascar https://abs.twimg.com/emoji/v2/... draggable=

, vanilla agroforests, rice paddies, land under shifting cultivation, forest fragments and old-growth forests form a diverse mosaic landscape. 2/15" title="In north-eastern #Madagascar https://abs.twimg.com/emoji/v2/... draggable="false" alt="🇲🇬" title="Flagge von Madagaskar" aria-label="Emoji: Flagge von Madagaskar">, vanilla agroforests, rice paddies, land under shifting cultivation, forest fragments and old-growth forests form a diverse mosaic landscape. 2/15" class="img-responsive" style="max-width:100%;"/>

Importantly, #vanilla agroforests differ in land-use history: they can be established on fallow land or inside forests, with strong implications for #Biodiversity and #EcosystemFunctions

See this thread about our paper in @ConLetters: 3/15 https://twitter.com/Dominic_Mart/status/1272429539713519623">https://twitter.com/Dominic_M...

https://twitter.com/Dominic_Mart/status/1272429539713519623

. @DomiSwb visited all our 80 @Diversity_Turn plots across seven land-use types to measure predation rate. 4/15

But how to measure predation rate? 5/15

He used fake caterpillars

https://abs.twimg.com/emoji/v2/... draggable="false" alt="🐛" title="Käfer" aria-label="Emoji: Käfer"> – standardized plasticine dummies – to measure 1) predation rate and 2) predator composition which he assessed by bitemark identification.

36 dummies per plot were exposed for 48 hours – summing up to 2880 exposures in total. 6/15

He used fake caterpillars https://abs.twimg.com/emoji/v2/... draggable=

– standardized plasticine dummies – to measure 1) predation rate and 2) predator composition which he assessed by bitemark identification. 36 dummies per plot were exposed for 48 hours – summing up to 2880 exposures in total. 6/15" title="He used fake caterpillars https://abs.twimg.com/emoji/v2/... draggable="false" alt="🐛" title="Käfer" aria-label="Emoji: Käfer"> – standardized plasticine dummies – to measure 1) predation rate and 2) predator composition which he assessed by bitemark identification. 36 dummies per plot were exposed for 48 hours – summing up to 2880 exposures in total. 6/15" class="img-responsive" style="max-width:100%;"/>

Predation rates where highest in the unburned land-use types old-growth forest, forest fragment and forest-derived vanilla. Rice paddies showed the smallest rates, but heterogeneity within land-use was high throughout. 7/15

In-depth analysis revealed that on-plot stem- and vegetation density were both positively associated with predation rate cross land-use types. 8/15

However, landscape-scale forest cover was also positively associated with predation rate. Predation rate differed between unburned and burned plots (that were once used for shifting hill rice cultivation). 9/15

The bitemark analysis further revealed differences in predator composition: Ants

https://abs.twimg.com/emoji/v2/... draggable="false" alt="🐜" title="Ameise" aria-label="Emoji: Ameise"> were the most important predators throughout, but predation by other groups, especially Gryllacrididae, differed between land-use types. 10/15

The bitemark analysis further revealed differences in predator composition: Ants https://abs.twimg.com/emoji/v2/... draggable=

were the most important predators throughout, but predation by other groups, especially Gryllacrididae, differed between land-use types. 10/15" title="The bitemark analysis further revealed differences in predator composition: Ants https://abs.twimg.com/emoji/v2/... draggable="false" alt="🐜" title="Ameise" aria-label="Emoji: Ameise"> were the most important predators throughout, but predation by other groups, especially Gryllacrididae, differed between land-use types. 10/15" class="img-responsive" style="max-width:100%;"/>

These differences in predator composition also became apparent in an NMDS. Particularly old-growth forest and forest fragments featured a different set of predators than all other land-use types. 11/15

Our results show that:
- Measuring predation rates is possible with dummy caterpillars
- Predation rates – a key ecosystem function - decline with tree loss on the plot- and landscape-scale.
- The plots’ land-use history determines the predator community 12/15

We also show that it is possible to reliably identify various predators from bitemarks – even in a tropical location.

This showed a shift in predator composition across the land-use gradient & showed that Malagassy Gryllacrididae are particularly vulnerable to LUC. 13/15

Congratulations @DomiSwb to this achievement & thanks for having me on board!

We are grateful to all involved farmers, to Gatien Rasolofonirina for field assistance, to @VWStiftung for funding, and to #ProjektDeal for #OpenAccess!

Paper link: https://doi.org/10.1111/1365-2664.13766">https://doi.org/10.1111/1...
14/15

Decreasing predation rates and shifting predator compositions along a land‐use gradient in Madaga...

Forested habitats feature higher predation rates and different predator compositions than other land‐use systems. Maintaining or restoring tree‐ and understorey‐rich vanilla agroforestry represents...

https://doi.org/10.1111/1365-2664.13766

btw: If you are more of a bird person: one of my PhD chapters investigates (endemic) bird diversity across the same land-use types & is now out in @Biotropica!

https://www.doi.org/10.1111/btp.12859">https://www.doi.org/10.1111/b... 15/15

Bird diversity and endemism along a land‐use gradient in Madagascar: The conservation value of...

Land‐use change is the most important driver of biodiversity loss worldwide and particularly so in the tropics, where natural habitats are transformed into large‐scale monocultures or heterogeneous...

https://www.doi.org/10.1111/btp.12859

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