Natural forests combat non-native tree invasions

The native biodiversity of natural forest patches like this one in the foreground play a crucial role in buffering against invasions by non-native plants and trees, while the non-native eucalypt plantation in the background provides the timber resource for countless products. Good land management is required to ensure that the non-native eucalypts fulfil their function, while the natural forest, which harbours the biodiversity that underpins a healthy landscape, needs to be carefully protected.

A new study, published recently in Nature, has found that the native biodiversity of natural forests largely buffers the severity of non-native tree invasions.

The bad news, however, is that humans remain mostly responsible for introducing non-native tree species to an area in the first place – either intentionally or accidentally.

These are two of the key findings from a global study to determine the relative importance of human activity, environmental conditions, and biological diversity as drivers of tree invasions worldwide. The study, titled “Native diversity buffers against severity of non-native tree invasions” was published in the journal Nature on Wednesday, 23 August 2023.

Prof. Cang Hui, holder of the South African research chair in mathematical and theoretical physical biosciences at Stellenbosch University (SU), and one of the co-authors of the study as part of the Global Forest Biodiversity Initiative (GFBI), says trees are exposed to a wide range of ecological and human factors, and tree invasions are both drivers and passengers of global environmental changes.

This is because of their size, long life span and important role in forestry, foraging, city landscaping and reforestation, as well as carbon sequestration and climate regulation. Yet invasion biologists have long been struggling to identify the ecological mechanisms driving the invasion success of a small portion of non-native tree species.

Their findings support the biotic resistance hypothesis, which holds that greater diversity in the native community will fill the ecological niches and reduce available resources, thereby limiting non-native species to take up niche spaces.

The prominent role of human activities, however, came as a surprise: “Our findings suggest that human activity may overwhelm ecological drivers of invasions and even reduce the influence of ecological processes,” he warns.

Three of the most frequent non-native trees in the GFBI database (left to right) Black Locust; Osage orange; Tree of Heaven (Photos courtesy iNaturalist, Dave Richardson, Rosario, and Gehardt).

Repeated human introductions of plant species, especially close to ports and airports, play an important role in the initial introduction process. The severity of the invasion, however, is predominantly a result of the intrinsic diversity of the native community.

It is therefore important to conserve natural forests to maintain high native tree diversity, they write in the paper.

Furthermore, because many tree species are introduced purposefully for forestry or to support local livelihoods, they recommend that local stakeholders are included when making decisions about how best to benefit from these managed forests.

Some of the other findings include:

Read the full article here: Delavaux et al. (2023) Native diversity buffers against severity of non-native tree invasions

Help protect natural forest & save the Cape Parrot

World Parrot Day, celebrated on 31 May 2023, puts the spotlight on the critically endangered Cape Parrot, colourful resident of South Africa’s Afromontane southern mistbelt forests. There are less than 2 000 Cape Parrots left in the wild as their habitat has been eroded by the consequences of extensive, uncontrolled logging in the past, on-going forest degradation, disease and the illegal capture of wild birds for sale.

Now communities, businesses and members of the public can get behind the Wild Bird Trust’s Cape Parrot Project to help protect and expand the natural forest habitats of this iconic bird in an effort to ensure its long term survival.

The current distribution of the Cape Parrot is restricted to a mosaic of Afromontane Southern Mistbelt forests from Hogsback in the Eastern Cape through to the southern KwaZulu-Natal. There is also a small and disjunct population in Limpopo province. Cape Parrots are dependent upon large indigenous trees, particularly Yellowwoods, for food and as nesting sites, where they use existing cavities to lay eggs.

The uncontrolled logging of these natural forests that started in the 19th century would have had a huge impact on the Cape Parrot population as mature hardwoods – especially yellowwoods - were targeted for felling. These natural forest patches are now protected for conservation purposes and logging is outlawed, but the forests are still under pressure from population growth and land use changes.

The Cape Parrot is also known as the Knysna papagaai, woudpapagaai (Afrikaans), isiKwenene (Zulu). isikhwenene (Xhosa) and hokwe (Tswana). It is only found in South Africa and has been listed as Birdlife’s Bird of the Year for 2023.

To ensure this species does not go extinct, the Cape Parrot Project is engaging with communities, organisations and the public to raise awareness of the threats the bird is facing and to educate people on how to maintain a healthy habitat for the parrot. The goal is a sustainable ecosystem for not just the parrots, but all the forest species and for surrounding communities.

The Cape Parrot Project team uses research and science to drive conservation action. A key strategy is to partner with local communities to get involved in habitat restoration. Alien vegetation is managed to assist natural forest regeneration, and planting of indigenous species is undertaken where appropriate.
Seeds are collected from a variety of local indigenous trees in the nearby forests and germinated in compost. Thousands of indigenous tree saplings are produced in community-run nurseries located close to the forests as well as the main nursery at the project base in Hogsback.

“Community members are encouraged to grow seedlings which the project then buys back. These seedlings are planted back into appropriate degraded forest habitat. Thus, the Cape Parrot Project strengthens local social-ecological resilience through creating livelihood opportunities in local communities that are dependent on a healthy ecosystem and their surrounding indigenous forest,” said Dr Francis Brooke, Research Manager for the Cape Parrot Project in Hogsback.

The project also engages with local schools encouraging children to become agents of positive environmental change, and to increase their appreciation for the indigenous forests and all the species that call these forests home.

By restoring the health of the natural forest patches, the project also contributes to mitigating the impacts of climate change and supporting local communities. Natural forests sequester significant amounts of carbon dioxide from the atmosphere and provide a suite of ecological services like improving air and water quality and protecting biodiversity.

Dr Kirsten Wimberger, Director of the Cape Parrot Project, said: “The restoration of forests campaign - Myforest - will be launched on World Parrot Day, 31 May, where the public can get involved by helping to protect the Cape Parrot and demonstrate their commitment to conservation in South Africa”.

As a partner of the Cape Parrot Project, participating companies can build on their sustainability portfolio while also raising awareness about the project. The Cape Parrot Project has a growing and dedicated following on social media, including conservationists, bird enthusiasts, and individuals who care about environmental issues. By partnering with the Cape Parrot Project, companies can pride themselves on adopting a social responsibility program that is making a difference and do their bit for the planet.

For more info visit www.wildbirdtrust.com


Cape parrots ahoy!!
by Chris Chapman
Passing through the tiny town of Creighton in southern KZN early one morning, my colleague James Ballantyne suddenly shouted “Cape parrots” and pulled over onto the side of the road to get a better look.

I could see a flock of birds disappearing over a nearby hill, but couldn’t make out what they were.

“Definitely Cape parrots,” said James. “Let's follow them and see where they go.”

With that he jumped back in the car and off we went in the general direction that the flock appeared to be taking, which was the opposite direction of our field day location. I was not convinced that this wild goose chase would yield anything of interest, and I was not aware that we even had a proper parrot in South Africa.

Soon we came to a clump of large yellowwoods just outside the town and James pulled over again. Sure enough there they were, barely discernible against the glare of the sky, high up in the canopy. I managed to get a photo of one of these parrots, and only when I got back home and enlarged the photo could I make it out properly.

Now I am a fan of the Knysna papagaai and keep an eye out for them whenever I am around a natural forest – although I haven’t seen one since. But I will keep looking!

My photo of the Knysna papagaai, high up in a yellowwood outside Creighton, southern KZN.

Gabon pushing for certified timber

Gabon Advanced Wood Sarl (GAW) is a company in Gabon which holds a timber concession. It recently obtained a new Forest Stewardship Council™ forest management certificate for its Ogooué concession in the south of Gabon, located in the Haut Ogooué and Ogooué Lolo provinces.

The company’s operations are located in the town of Moanda and supply certified logs to processing industries established in the Nkok Special Economic Zone (SEZ), a 1126 ha multi-sectoral industrial park located 27 km from Libreville. It includes industrial, commercial and residential zones. In its entirety, it brings together 144 companies from 19 countries operating in 22 industrial sectors, including a cluster of 84 companies dedicated to wood processing. (https://www.gsez.com/).

The Ogooué concession covers 179 861 hectares of forests, including 25 996 hectares of strictly conservation area. The concession includes about 309 inventoried tree species and iconic and threatened mammalian species such as elephants, chimpanzees and gorillas.

This is the first FSC forest management certificate in Gabon since 2014 and an important milestone for Gabon's ambition to have all their forest concessions certified by 2025. With this certificate, the total area of natural forest responsibly managed in Gabon under FSC certification reaches 2 241 051 hectares.
There are now more than 5.5 million hectares of FSC certified forest in three countries of the Congo Basin: Cameroon (341 708 ha), Gabon (2 241 051 ha) and the Republic of Congo (2 989 168 ha).

Covered 85% by forest, on 22 million hectares, Gabon has a stock of exploitable wood of 130 million m3 of Okoumé and 270 million m3 of other species. GSEZ has enabled the country to develop and modernise a wood sector that was previously not very promising by relying on specialisation, one-stop services and alignment with the national development strategy. With 3.4 million m3 produced each year, Gabon has become Africa’s leading producer and exporter of tropical plywood, and the world’s second largest exporter. The country intends to go further in adding value to its wood products by transforming GSEZ into a centre for the manufacture of "Made in Gabon" furniture by 2025.

Faced with growing demand, GSEZ has made sustainability, traceability and certification of wood sourced in Gabon and processed at its facilities one of its priorities. All of Gabon’s forest concessions are operated according to the sustainable forest management practices prescribed by the Gabonese Forest Code. In terms of traceability, since October 2018, GSEZ has benefited from the services of the Tracer-Nkok agency, which filters the logs entering the zone in order to limit the risk of illegal timber as much as possible. By 2022, all the country’s forest concessions will be certified by the Forest Stewardship Council (FSC) and/or PEFC Gabon in order to improve the traceability of the wood and ensure respect for communities and workers.