A lone tree makes it easier for birds and bees to navigate farmland, like a stepping stone between habitats

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Carla Archibald, Deakin University; Eduardo van den Berg, Federal University of Lavras, and Jonathan Rhodes, The University of QueenslandVast, treeless paddocks and fields can be dangerous for wildlife, who encounter them as “roadblocks” between natural areas nearby. But our new research found even one lone tree in an otherwise empty paddock can make a huge difference to an animal’s movement.

We focused on the Atlantic Forest in Brazil, a biodiversity hotspot with 1,361 different known species of wildlife, such as jaguars, sloths, tamarins and toucans. Habitat loss from expanding and intensifying farmland, however, increasingly threatens the forest’s rich diversity of species and ecosystems.

We researched the value of paddock trees and hedges for birds and bees, and found small habitat features like these can double how easily they find their way through farmland.

This is important because enabling wildlife to journey across farmlands not only benefits the conservation of species, but also people. It means bees can improve crop pollination, and seed-dispersing birds can help restore ecosystems.

Connecting habitats

Lone trees in paddocks, hedges and tree-lined fences are common features of farmlands across the world, from Brazil to Australia.

They may be few and far between, but this scattered vegetation makes important areas of refuge for birds and bees, acting like roads or stepping stones to larger natural habitats nearby.

Scattered paddock trees, for instance, offer shelter, food, and places to land. They’ve also been found to create cooler areas within their canopy and right beneath it, providing some relief on scorching summer days.

Hedges and tree-lined fences are also important, as they provide a safe pathway by providing hiding places from predators.

White-browed meadowlark perched on a bush in a farm paddock within the Atlantic Forest.
Milton Andrade Jr, CC BY

For our research, we used satellite images of the Atlantic Forest and randomly selected 20 landscapes containing different amounts of forest cover.

We then used mathematical models to calculate the habitat connectivity of these landscapes for three groups of species — bees, small birds such as the rufous-bellied thrush, and large birds such as toucans — based on how far they can travel.

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And we found in areas with low forest cover, wildlife is twice as likely to move from one natural habitat to another if paddock trees and hedges can be used as stepping stones.

We also found vegetation around creeks and waterways are the most prevalent and important type of on-farm habitat for wildlife movement. In Brazil, there are legal protections for these areas preventing them from being cleared, which means vegetation along waterways has become relatively common compared to lone trees and hedges, in places with lower forest cover.

Insights for Australia

While the contribution of lone trees, hedges and tree-lined fences towards conservation targets is relatively low, our research shows they’re still important. And we can apply this knowledge more widely.

Koalas use roadside vegetation for feeding and resting.
Shutterstock

For example, in Australia, many koala populations depend on scattered trees for movement and habitat. In 2018, CSIRO researchers in Queensland tracked koalas using GPS, and found koalas used roadside vegetation and scattered trees for feeding and resting significantly more than they expected.

Likewise, lone trees, hedges and tree-lined fences can also facilitate the movement of Australian fruit-eating birds such as the olive-backed oriole and the rose-crowned fruit dove. Improving habitat connectivity can help these birds travel across landscapes, feeding and dispersing seeds as they go.

In fragmented landscapes, where larger patches of vegetation are hard to find, dispersing the seeds of native plants encourages natural regeneration of ecosystems. This is a key strategy to help achieve environmental restoration and conservation targets.

Policies overlook lone trees

In Brazil, there’s a strong initiative to restore natural areas, known as the Brazilian Pact for Restoration. This pact is a commitment from non-government organisations, government, companies and research centres to restore 15 million hectares of native vegetation by 2050.

However, the pact doesn’t recognise the value of lone trees, hedges and tree-lined fences.

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Likewise, the Brazilian Forest Code has historically provided strong legal protection for forests since it was introduced. While this policy does value vegetation along waterways, it overlooks the value of lone trees, hedges or tree-lined fences.

These oversights could result in poor connectivity between natural areas, seriously hampering conservation efforts.

Australia doesn’t fare much better. For example, in Queensland, the native vegetation management laws protect only intact native vegetation or vegetation of a certain age. This means scattered, but vital, vegetation isn’t protected from land clearing.

Small habitat features scattered across a farm paddock in the Atlantic Forest.
Flávia Freire Siqueira, CC BY., Author provided

Helping your local wildlife

But farmers and other landowners in Australia can make a big difference through land stewardship grant schemes (such as from Landcare) and private land conservation programs (such as Land for Wildlife or conservation covenants).

These schemes and programs can help landowners finance revegetation and protect native vegetation. Grants and programs vary by state and territory, and local council.

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Restoring natural areas is a key goal on the global conservation agenda for the next decade, and it’s clear that lone trees, hedges and tree-lined fences on farms may play a larger role than once thought.

So think twice before you remove a tree or a hedge. It might be a crucial stepping stone for your local birds and bees.

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The authors gratefully acknowledge the contributions of Dr Flávia Freire Siqueira who led this research collaboration, and co-authours Dr Dulcineia de Carvalho and Dr Vanessa Leite Rezende from the Federal University of Lavras.

Carla Archibald, Research Fellow, Conservation Science, Deakin University; Eduardo van den Berg, , Federal University of Lavras, and Jonathan Rhodes, Associate Professor, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Sharks: one in four habitats in remote open ocean threatened by longline fishing

Though they’re protected worldwide, great white sharks encounter longline fishing vessels in half of their range.
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David Sims, University of Southampton

Unlike the many species which stalk the shallow, coastal waters that fisheries exploit all year round, pelagic sharks roam the vast open oceans. These are the long-distance travellers of the submarine world and include the world’s largest fish, the whale shark, and also one of the fastest fish in the sea, the shortfin mako shark, capable of swimming at 40mph.

Because these species range far from shore, you might expect them to escape most of the lines and nets that fishing vessels cast. But over the last 50 years, industrial scale fisheries have extended their reach across the world’s oceans and tens of millions of pelagic sharks are now caught every year for their valuable fins and meat.

On average, large pelagic sharks account for over half of all shark species identified in catches worldwide. The toll this has taken on species such as the shortfin mako has prompted calls to introduce catch limits in the high seas – areas of the ocean beyond national jurisdiction where there is little or no management for the majority of shark species.

We wanted to know where the ocean’s shark hotspots are – the places where lots of different species gather – and how much these places are worked by fishing boats. We took up the challenge of finding out where pelagic sharks hang out by satellite tracking their movements with electronic tags. This approach by our international team of over 150 scientists from 26 countries has an important advantage over fishery catch records. Rather than showing where a fishing boat found them, it can precisely map all of the places sharks visit.

Nowhere to hide

For a new study published in Nature we tracked nearly 2,000 sharks from 23 different species, including great whites, blue sharks, shortfin mako and tiger sharks. We were able to map their positions in unprecedented detail and discern the most visited hotspots where sharks feed, breed and rest.

Hotspots were often located in frontal zones – boundaries in the sea between different water masses that can have the best conditions of temperature and nutrients for phytoplankton to bloom, which attracts masses of zooplankton, as well as the fish and squid that sharks eat.

Then we calculated how much these hotspots overlapped with global fleets of large, longline fishing vessels, which we also tracked by satellite. This type of fishing gear is used very widely on the high seas and catches more pelagic sharks than trawls and other gear. Each longline vessel is capable of deploying a 100km long line bearing over 1,000 baited hooks.

We found that even the most remote parts of the ocean that are many miles from land offer pelagic sharks little refuge from industrial-scale fishing fleets. One in four of the places sharks visited each month overlapped with the areas longline fishing vessels operated in.

Sharks such as the North Atlantic blue and the shortfin mako – which fishers also target for their fins and meat – were much more likely to encounter these vessels, with as much as 76% of the places these species visited most in each month overlapping with where longline vessels were fishing. Even internationally protected species such as great whites and porbeagle sharks encountered longline vessels in half of their tracked range.

It’s now clear that much of the world’s fishing activity on the high seas is centred on shark hotspots, which longlines rake for much of the year. Many large sharks, which are already endangered, face a future without refuge from industrial fishing in the places they gather.

High seas marine protected areas

The maps of shark hotspots and longline fishing activity that we created can at least provide a blueprint for where large-scale marine protected areas aimed at conserving sharks could be set. Outside of these, strict quotas could reduce catches.

The United Nations is creating a high seas treaty for protecting ocean biodiversity – negotiations are due to continue in August 2019 in New York. They’ll consider large-scale marine protected areas for the high seas and we’ll suggest where these could be located to best protect pelagic sharks.

Satellite monitoring could give real-time signals of where sharks and other threatened creatures such as turtles and whales are gathering. Tracking where these species roam and where fishers interact with them will help patrol vessels monitor these high-risk zones more efficiently.

Such management action is overdue for many shark populations in the high seas. Take North Atlantic shortfin makos – not only are they overfished
and endangered, but now we know they have no respite from longline fishing during many months of the year in the places they gather most often. Some of these shark hotspots may not exist in the near future if action isn’t taken now to conserve these species and the habitats they depend on.

David Sims, Professor of Marine Ecology, University of Southampton

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Koalas: Trees the Key to Growing Populations

A recent report on Koala populations has concluded that more trees are the key to growing populations and spreading habitats. Hardly sounds surprising does it – the article is linked to below.

For more visit:
http://sydney.edu.au/news/84.html?newsstoryid=6826

 

Tasmania: Ocean Warming is Happening

According to a recent report ocean warming is happening off the east coast of Tasmania. The consequences of such warming includes the decline of important kelp forests, fish distribution and changes in fish habitats, and a growing population of destructive sea urchins.

For more visit:
http://www2.utas.edu.au/tools/recent-news/news/cascade-of-climate-change