Restoring the World Forests, One Species at a Time

B-08: Forest Regeneration: Challenges and Prospects

 

When nine forest scientists from all around the world are put in one room to talk about forest regeneration, it’s very likely the international audience will learn about many tree species. From South America, to western Australia, to the Rocky Mountains, the speakers divulged an array of plant species that are either being restored for the sake of the ecosystem, or to save the species from perishing.

Photo by Ollivier Girard for Center for International Forestry Research (CIFOR).
Photo by Ollivier Girard for Center for International Forestry Research (CIFOR).

The Atlantic Rainforest in the southern part of Brazil was the study area for two of the presenters. As we are well aware, the rainforest of Brazil is being depleted at an astonishing rate for the sake of agriculture and livestock. According to Leonardo Augusto Martins, 88 percent of Brazil’s natural forests are lost, which amounts to about 20,000 different plant species.

In Brazil, and also in Costa Rica, forest managers have to carefully consider the most effective ways to restore deforested lands after being abandoned for years. Ricardo Santiago-Garcia pointed out from the time of abandonment until reforestation takes place can be anywhere from 26 to upwards of 52 years. To ensure the quickest recovery, Eliana Cardoso-Leite suggested active regeneration techniques using seedlings as the most effective practice. Employing measures of success, such as species richness, seedling height and diameter, treatments using seeds, and agroforestry were compared to seedling planting. The planting proved to be the most ideal method but it’s typically the most costly.

Across the Pacific, Katinka Ruthrof from Australia introduced another approach to regeneration using Eucalyptus gomphocephala, also known as tuart. Native to western Australia, tuart is a serotinous species with a niche distribution that is being threatened by land clearing, drought, and fire. The treatments examined here included inaction, facilitated regeneration, and active regeneration using a bed of ash. The goal of building the ash beds was to mimic the natural environment conducive for truart seeds. Ash is considered advantageous for seed germination because it increases water availability and supplies enough nutrients to prevent competition of resources from other plant species. Unfortunately, in the end, ants removed the seeds, while any established seedlings were ravaged by herbivores, namely rabbits.

In North America, where conifers are the dominant species of interest, the state of Colorado is dealing with the major loss of lodgepole pine due to the mountain pine beetle. As the trees begin to die and lose their needles, the canopy opens up and more light is able to reach the understory. This is favourable for species like lodgepole pine and aspen, another post-disturbance colonizer. In certain cases, the pine was able to come back, but on sites where grass dominated the understory, seedlings were rare. Aspen is also prone to browsing from ungulates and other herbivores, which also compromises the survival of this deciduous species. However, where the dead pine fell, the aspen was able to benefit from the added protection. As the decaying trees fell, it is likely the ground became too difficult for the grazers to reach the aspen, which may have assisted in its regeneration.

Jorg Kunz of Germany introduced Sorbus torminalis, better known as the checker tree. Drought-tolerant and able to reproduce via sprouting, it is an ecological and economically important tree in central Europe. While it has a large distribution, the checker tree makes up only 0.02 percent of European forests because it is physiologically limited to its niche micro-environment.

To finish this session, Sara Goeking explained the efforts taked to save the whitebark pine in the northern Rocky Mountains of Utah. This is another niche species that grows in rugged alpine terrain and is ecologically important for food, and aesthetics as well. Whitebark pine is at risk due to mountain pine beetle and blister rust and Goeking asserted that this is a tree species that warrants protection. The study found where Vaccinium scoporium, more commonly known as grouseberry or huckleberry, occurred, the whitebark pine seedling density was somewhat greater than those sites without the Vaccinium species. This common occurrence warrants further exploration.

There is a multitude of research happening throughout the world examining the restoration of valuable ecosystems and tree species. Whether economically or ecologically important, it is crucial to incorporate as much knowledge, whether new or old, into land management decisions. In doing so, we can only hope to save dwindling forests and threatened species, especially during a time when forest restoration is more vital than ever.

 

Written by: Nichola Gilbert

 

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