Minimising ecological and social externalities in tropical crop expansion

Grantham Scholar Maria Wang Mei Hua researches spatial models for the expansion of rubber agriculture that maximize ecological, social and economic sustainability.


With growing demand for tropical agricultural products, including palm oil, rubber and wood-pulp, there is an urgent need to find sustainability between natural ecosystems, people and economics. Each crop has an emerging crop-specific sustainability initiative in varying degrees of development aimed at reducing the wider environmental and social damage they cause (negative externalities).

However, planning methods and resulting land-use plans of government resource-use agencies and industry rarely take into account competition between crops and agricultural externalities, which increases the conflicts between environment, society and different crop types for land.

Focusing on natural rubber in Southeast Asia and West Africa, our project aims to develop a spatial model for the expansion of rubber agriculture and simulate optimal landscape plans for multiple crops that maximize ecological, social and economic sustainability.

In addition, via collaboration with a network of commodity producer and purchaser companies, we hope to assess the most relevant ecological and social impacts of rubber agriculture and expansion, and analyse different ways of internalizing externalities.

Outreach and impact

Decolonising research guide for PhD researchers. Maria Wang Mei Hua and a team of Grantham Scholars have made a guide to decolonising research. This guide is aimed at Grantham Scholars, but would be useful for all researchers. Maria and her group were shortlisted for ‘Outstanding Contribution to Postgraduate Student Diversity’ for their decolonisation work.


In 2021, Maria and a group of Grantham Scholars went to COP26 as official observers for the University of Sheffield. Before COP we spoke to each of them about their hopes and fears for this pivotal event.

During COP Maria was interviewed by BBC Radio Sheffield. Listen to the interview on BBC Sounds, Maria is at 2:12.

Maria’s sustainability work at The University of Sheffield

I am passionate about wider engagement beyond my department and my research. As part of a team of Grantham scholars tasked with producing an audit report to inform the University of Sheffield’s first Sustainability Strategy. We spent a few months in 2018 conducting the audit and writing a 50-page audit report (read the strategy here).

I am also part of the Sustainability Committee at the Students’ Union, where we represent the student voice in the SU and at the University via different platforms. We organise events to engage students about sustainability issues (ranging from the injustice in fast fashion; debating a ban on meat sales at the SU; and social events to bring together sustainability-minded people), and campaign for changes at the university.

Blogs & interviews

Freshly opened cempedak and its gorgeous fleshy fruits
Freshly opened cempedak and its gorgeous fleshy fruits. Photo credit: Maria Wang

Maria was interview by Mongabay (an award-winning, non-profit media outlet with over 110K followers on Twitter). She spoke to them about her report into rubber agroforestry (see in publications). You can read the interview here.

A group of Grantham Scholars went to the Time Is Now protests in London, where they met with Sheffield Central MP Paul Blomfield. Maria was one of them, and she explained why in this interview. Read: The Time Is Now: Grantham Scholars at ‘mass lobby’

Can you name a wild animal from Malaysia? Not many can. This is just one of the facts Maria learned at a conservation conference hosted in Kuala Lumpur, the capital city of her home country. Read: Photoblog: Can you name a wild animal from Malaysia?

Maria also wrote a blog about her work during her MS studying cempedak. Cempedak is an amazing fruit that grows in Maria’s home country of Malaysia. And Maria’s blog has been read thousands times from places all over the world. Read: Cempedak, A Funky Tropical Fruit You’ve Probably Never Heard Of.

Maria Wang Mei Hua’s publications

Rubber Agroforestry, Feasibility at Scale.

By Maria Wang Mei Hua, Grantham Centre for Sustainable Futures and Department of Animal and Plant Sciences, University of Sheffield, UK. Eleanor Warren-Thomas, School of Natural Sciences, Bangor University, UK. Associate Professor Dr. Thomas Cherico Wanger, Sustainability, Agriculture & Technology, Westlake University, China; Agroecology, University of Göttingen, Germany.

Reconciling Rubber Expansion with Biodiversity Conservation.

Wang et al., 2020, Current Biology 30, 1–8 October 5, 2020 © 2020 Elsevier Inc. ll

Origin and diversity of an underutilized fruit tree crop, cempedak (Artocarpus integer, Moraceae).
Maria M. H. Wang Elliot M. Gardner Richard C. K. Chung Ming Yee Chew Abd Rahman Milan Joan T. Pereira Nyree J. C. Zerega

Social media

You can find out more about Maria’s work on her research group webpage

Or you can connect with her on LinkedIn

Plus you can find out more about her research on Google Scholar




Martin Hollands

Birdlife International

Roman Carrasco

National University of Singapore