Sunday, 12 January 2020

Studying land cover transformation in the Savé-Limpopo Lowveld of Zimbabwe.

The loss of biodiversity in sub-Saharan Africa is in large-part attributable to anthropogenic activity; particularly agricultural expansion, with concomitant deforestation, human–wildlife conflicts and illegal harvesting. The Millennium Ecosystem Assessment has linked biodiversity decline in Africa to habitat loss through agricultural growth, compounded by poverty and poor governance. Privately owned conservancies (de facto protected areas) in Zimbabwe, mostly in the Savé-Limpopo lowveld, were targeted under land reform programme, from 2000 onward. Land reform in the Savé-Limpopo lowveld appears to have been more political than environmental; wildlife was all but eradicated on resettled conservancies, and even a part of Gonarezhou National Park was occupied. In the Savé Valley Conservancy alone, 6454 wild animals were killed illegally from 2001 to 2009, including critically endangered species such as Black Rhinoceros, Diceros bicornis. Indigenous woodlands were extensively cleared, and wildlife corridors impeded. Supporters of land reform indicate that local communities simply exercised their right to act in their own self interest, and that localised resource management is no longer exclusive in nature.

In a paper published in the African Journal of Ecology on 25 November 2019, Lochran Traill of the School of Biological and Environmental Sciences at Liverpool John Moores University and the School of Animal, Plant and Environmental Sciences at the University of the Witwatersrand, and Jolene Fisher, also of the School of Animal, Plant and Environmental Sciences at the University of the Witwatersrand, describe the results of a study of land cover change in the Savé-Limpopo lowveld since 2000.

While fortress conservation is subject to criticism, protected areas are still successful in mitigating species' loss in Africa. Protected areas provide critical refuge to flora and fauna in an anthropogenic landscape, in particular threatened and endemic species, and further create millions of jobs through the tourism industry. An analysis on the conservation effectiveness of protected areas globally found some variance in the capacity of reserves and parks to protect species' populations, but the overall effect to be positive. Protected areas have also been found to reduce deforestation, although substantial variance exists within and between countries. Despite the positive conservation outcomes of protected areas, these can impose social costs on local communities, through foregone economic opportunities and human–wildlife conflict.

The opportunity costs of protected areas, and lack of support for wildlife conservation outside of formal reserves has prompted legislation (in some African states) for the devolved responsibility of wildlife management to land-owners or communities. Wildlife is subsequently seen as a grass-root resource that has the potential to prosper if land managers, through proprietorship, can integrate wildlife to their own advantage. Zimbabwe, until recently, provided a suitable case-study on the success of this policy, through the country's CAMPFIRE programme that transferred conservation decision-making to poor rural communities, and the shift from pastoralism to wildlife-management on many private properties, and the ultimate unification of these into conservancies.

Although indigenous woodland loss on lowveld protected areas post-2000 has been studied previously, this has not been quantified in the Savé-Limpopo Region. Traill and Fisher used remote sensing to estimate the loss of woodlands in three lowveld protected areas; the Chiredzi River and Savé Valley conservancies, and Gonarezhou National Park from 2000 to 2015. They also provide some recommendation on ways forward; although our their work is intended to be more useful as a scientific baseline of tree cover within the protected areas in the region pre-2000. This should act to counter shifting baselines regards future conservation decisions.

The study sites, Chiredzi River and Savé Valley conservancies, and Gonarezhou National Park, within the Save-Limpopo lowveld, Zimbabwe, are situated approximately 460 m above sealevel. To assess the loss of woody cover in each protected area, Traill and Fisher used the Hansen Global Forest Change software package. Tree cover in 2000 was quantified using the Treecover2000 software, which measures canopy closure for vegetation taller than 5 m, per 30 m pixel. Tree loss was
measured using the Loss Year software which is an annual measurement of loss of vegetation from a forest to nonforest condition, from 2001 to 2015. Land under subsistence farming and formal agriculture in Chiredzi and Savé Valley conservancies were manually digitised in ArcMap from a Landsat 7 image for August 2000 and a Landsat 8 image for August 2015. August images (early dry season) were chosen as cloud cover was relatively low during this time. 

The location of study sites in Zimbabwe's South-East Lowveld. Shown here are Gonarezhou  National Park, and Chiredzi River and Savé Valley conservancies. Traill & Fisher (2019).

Following land reform in 2000, substantial areas of two protected areas in Zimbabwe's Savé-Limpopo lowveld were transformed from indigenous woodland to subsistence-based farmland. Traill and Fisher's results show that approximately 60% of the Chiredzi River and 16.5% of the Savé Valley Conservancies were converted to subsistence agricultural land (between 2000 and 2015. Similar findings regarding forest transformation following land reform in Zimbabwe have been documented elsewhere, as well as increased incidence of soil degradation and loss.

Spatial representation of land cover change in Chiredzi River and Savé Valley conservancies. (a) The proportion of land under ‘commercial cropping’ and wildlife at the start of 2000 and (b) the proportion of land under ‘commercial cropping’ and ‘subsistence agriculture’ by 2015. The default background colour is land given to wildlife. Traill & Fisher (2019).

The rate of indigenous woody cover loss following land reform in the lowveld was substantial. Much of this occurred over just one decade; from 2001 to 2010, the rate of woody cover loss in Chiredzi River Conservancy was 7.081 km² per annum, the rate of loss in Savé Valley was 9.797 km² per annum, and in Gonarezhou National Park the rate was 0.806 km² per annum. There was variance around per annum woody cover loss, although it is apparent that much tree cutting occurred over 10 years. The cumulative loss or full loss of native woody plant cover from 2000 to 2015 was 75.47 km² in Chiredzi River Conservancy, 107.316 km² for Savé Valley and 9.542 km² in Gonarezhou National Park. Note that ‘woody cover’ here is a different parameter to ‘area of land under subsistence agriculture’; woody cover was defined as canopy closure for all vegetation greater than 5 m in height and estimated quantitatively through remote sensing.

Indigenous trees on lowveld protected areas appear to have been removed for a number of reasons; ostensibly cleared to make way for fields, much of the timber would likely have been used as fuelwood, or sold informally. Land reform was typified by forest clearance for access to arable land, fuelwood, pole construction and wood sale. Tree removal appeared therefore to serve two purposes; fuelwood and timber sales to augment incomes, and land clearance for agriculture, to provide further diversification of income. Income generation appears to have been a driver of the illegal harvest of vertebrate fauna resident on these protected areas prior to land reform; previous studies have found bushmeat hunting in the lowveld to be conducted by unemployed young men, who used the funds generated from the sale of bushmeat to buy food.

Land reform in Zimbabwe was in part driven by political expediency, and the lack of planning regards resettlement of people on lowveld protected areas, and the lack of subsequent support, perhaps played a role in subsequent deforestation and widespread illegal harvest, as well as the spread of disease such as foot-and-mouth.

Land reform is known to have a negative impact on biological diversity, in part because the process of transformation from single-large to multiple-small worked plots brings people into direct conflict with wildlife. The process in the Zimbabwean lowveld has also restricted the development of wildlife corridors in the region, linking protected areas to the Great Limpopo Transfrontier Park.

Proponents of reform have rightly indicated that poor, marginalised people exercised agency under land reform, and forced a shift from ‘exclusionary governance to pro-people democratic governance of Forest Protected Areas and other resources’. The conservation movement is increasingly aware that protected areas impose an opportunity cost on poor, rural people and that humanitarian needs must be taken into account. Zimbabwean conservationists have, to their credit, largely pioneered devolved community-based conservation, and there has been past success in the country through the CAMPFIRE programme. A number of studies published over the past decade discuss ways forward for lowveld protected areas, or conservancies and poor communities now resettled in the area. and Traill and Fisher feel they have little to add to that debate, other than to offer their support for community-based conservation. They are however somewhat surprised that much of the discussion around land reform in Zimbabwe implicitly assumes a long-term continuation of a large, rural-based populace, and not an urbanised, industrialised future. There also appears to be little discussion around alternative farming techniques that could alleviate land pressures.

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