Importance, Destruction and Conservation of Vegetation – Vegetation in Rwanda (Senior 4 Geography) | Ganzaa

Vegetation in Rwanda

Lessons

Senior 4 · Geography

Vegetation in Rwanda

3 lessons

Lesson 3 of 3

Importance, Destruction and Conservation of Vegetation

25 min

A forest that shrank by 97%

In 1960 the Gishwati forest on the Congo–Nile Ridge covered about 28,000 ha. From the 1980s it was cleared for farms and pasture, and after 1994 for settlement. REMA's 2009 report put what was left at about 700 ha (REMA, 2009). Gishwati is the most extreme case, but Figure 4 shows it was not the only one.

Figure 4. Recorded losses of natural vegetation in Rwanda, drawn by Ganzaa from REMA (2009).

Look for a pattern. Which losses were caused by the search for farmland, which by fuel and which by fire? This lesson asks why vegetation matters, why it is destroyed and how it can be conserved.

Why vegetation matters

Value	How vegetation provides it	Rwandan evidence
Energy	Firewood and charcoal for cooking	Forests supplied about 86% of primary energy, mainly for cooking (REMA, 2021)
Economy	Timber, poles, tourism	Forestry contributed about 6% of GDP in 2020; tourism earned US$121 million in 2020 (REMA, 2021)
Water	Forested catchments store rain and release it slowly to rivers	Forested catchments supply much of the water used downstream (REMA, 2021)
Soil	Roots bind soil; leaves break the force of rain	Bare slopes erode and slide in heavy rain
Climate	Trees store carbon	About 135 tonnes of carbon per hectare of forest (FAO, 2020, in REMA, 2021)
Biodiversity	Habitat for wildlife	Mountain gorillas and golden monkeys (Volcanoes); chimpanzees (Nyungwe, Gishwati); 670 bird species recorded in Rwanda (REMA, 2009)
Health and crafts	Medicinal plants, papyrus, bamboo	Papyrus is used for mats, roofing and ceilings (REMA, 2009)

Economists add these values together as the total economic value of an ecosystem. For example, a national study valued the Mukura landscape at about US$1.47 million a year, or US$817 per hectare per year (Republic of Rwanda, 2020, in REMA, 2021).

Definition

Deforestation: the permanent removal of forest so that the land is used for something else (farms, pasture, settlement). Degradation: the forest remains, but is thinned or damaged (by fire, cutting or grazing) so that it provides less.

Conservation: the protection, careful use and restoration of natural resources so that they last. Buffer zone: a belt of controlled land use around a protected area that reduces pressure on it.

Causes of vegetation destruction

Demand for farmland and pasture. A dense, mostly rural population needs land. Parts of the Volcanoes park were cleared in 1958 and for pyrethrum in 1969–1973; Gishwati was cleared for farms and pasture from the 1980s.
Settlement. After the 1994 Genocide against the Tutsi, land was needed to settle returning refugees: Akagera National Park was reduced to 108,500 ha in 1997, and people were settled in Gishwati (REMA, 2009).
Fuel. Charcoal for Kigali wiped out most of the woody savannah and gallery forest of Bugesera in the 1980s (REMA, 2009).
Fire. Fires, many started by honey collectors, burned about 12,800 ha of Nyungwe between 1996 and 2003; bushfires are frequent in Akagera in the dry seasons.
Mining, bamboo cutting and poaching inside Nyungwe, Gishwati and the Volcanoes park (REMA, 2009).
Exotic trees. Eucalyptus and pine planted in buffer zones can spread and compete with the natural forest (REMA, 2009).

Worked example 1: how fast did Gishwati disappear?

Problem. Gishwati covered 28,000 ha in 1960 and about 700 ha in 2009. Find the percentage lost and the average annual rate of loss, assuming a constant percentage loss each year.

Percentage lost.

\frac{28\,000 - 700}{28\,000} \times 100 = 97.5\%

Annual rate. If a fraction $r$ is lost each year for $n = 49$ years, $A_{2009} = A_{1960}(1 - r)^{n}$ , so

1 - r = \left(\frac{700}{28\,000}\right)^{\frac{1}{49}} = 0.025^{\,0.0204} = 0.927 \qquad r = 0.073 = 7.3\%\ \text{a year}

Interpretation. On average, about one-fourteenth of what remained was cleared every year for half a century. In reality the loss came in bursts (the 1980s and after 1994), which a constant-rate model hides.

Worked example 2: the charcoal savannah of Bugesera

Data. Bugesera had over 50,000 ha of woody savannah in 1983 and under 10,000 ha in 1988, mainly cut for charcoal for Kigali (REMA, 2009, citing MINAGRI).

1 - r = \left(\frac{10\,000}{50\,000}\right)^{\frac{1}{5}} = 0.2^{\,0.2} = 0.725 \qquad r \approx 27.5\%\ \text{a year}

Because the 1988 figure was "under 10,000 ha", the true rate was at least this high: almost four times Gishwati's average rate. Lesson: a city's demand for fuel can strip vegetation far from the city itself.

Effects of vegetation destruction

Effect	Explanation and example
Soil erosion and landslides	Without roots and leaf cover, rain washes soil off steep slopes; cleared slopes in the west and north slide in heavy rain.
Water problems	Rain runs off quickly instead of soaking in, so floods rise and dry-season flows fall; rivers carry silt into lakes and dams.
Loss of biodiversity	Poaching and habitat loss exterminated elephants and buffalo in Nyungwe (REMA, 2009); Gishwati's chimpanzees and other forest animals lost almost all of their habitat.
Fuel shortage	Wood becomes scarce and expensive, and people walk farther for firewood.
Climate	Burned or rotting wood releases its carbon as carbon dioxide; local rainfall and temperature can change.
Lost income	Fewer tourists, medicines, crafts and timber.

Conserving vegetation in Rwanda

Protected areas. Four national parks: Volcanoes, Nyungwe, Akagera and Gishwati-Mukura, created by a law of 2015 and gazetted in 2016 from the Gishwati (1,570 ha) and Mukura (1,988 ha) reserves. In 2020 UNESCO named the Gishwati-Mukura Landscape a Biosphere Reserve (REMA, 2021).
Sharing benefits. About 10% of tourism revenue from the park at the core of the Gishwati-Mukura Biosphere Reserve goes to community projects (UNESCO, 2020, in REMA, 2021), so neighbours gain from protecting it.
Restoration. Since 2015 the LAFREC project has restored the Gishwati-Mukura landscape, including silvopasture (trees planted on pasture). In Nyungwe, ferns are cleared from burned plots so that trees can return: more than 70 ha since 2004 (REMA, 2021).
Buffer zones of tea and woodlots around Nyungwe and Gishwati separate farms from the forest and give local people work.
Less demand for wood: improved cookstoves and other fuels; agroforestry and woodlots on farms.
Wetland protection. Rugezi is a Ramsar site (a wetland of international importance) (REMA, 2021).
Education, laws and patrols against fire, poaching, illegal mining and bamboo cutting.

Warning

"Planting trees" is not the same as "conserving vegetation". A eucalyptus woodlot provides fuel and protects soil, but it is not a habitat for chimpanzees, and REMA warns that exotic trees in buffer zones can threaten the natural forest. In an evaluation answer, distinguish protecting natural vegetation from planting new trees, and say what each achieves.

TravelRwanda: "Conserving Africa's Oldest Montane Rainforest: Nyungwe National Park". As you watch, list the threats to Nyungwe and the conservation measures you see, and compare them with this lesson.

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Practice

Distinguish deforestation from forest degradation, giving a Rwandan example of each.
Give four ways in which vegetation is important to Rwanda, with evidence for each.
Explain three human causes of the destruction of natural vegetation in Rwanda.
Mukura forest reserve covered about 2,100 ha in 1990 and 1,600 ha in 2006 (REMA, 2009). Calculate the percentage lost and the average loss in hectares per year.
Explain how the loss of forest on the slopes around a wetland can reduce the water reaching a hydroelectric dam.
Describe how a buffer zone helps to protect a national park.
"Rwanda's conservation policies have succeeded." Evaluate this statement using evidence from this lesson.

Show answersHide answers

Deforestation is permanent removal for another land use (Gishwati cleared for pasture); degradation is damage to forest that remains (fires in Nyungwe).
Any four with evidence, e.g. energy (86% of primary energy), economy (forestry about 6% of GDP in 2020), soil and water protection on steep catchments, biodiversity (gorillas, chimpanzees, 670 bird species), carbon storage, crafts and medicines.
Any three: clearing for farms and pasture (Volcanoes park, Gishwati); settlement of returnees (Akagera reduced in 1997); charcoal for towns (Bugesera); fires (Nyungwe); mining, bamboo cutting, poaching.
$\frac{2\,100 - 1\,600}{2\,100} \times 100 = 23.8\%$ ; $\frac{500}{16} = 31$ ha a year.
Without forest, rain runs off faster, carries soil into the wetland and less water soaks in and is released slowly; the wetland silts up or is drained, so less water flows on to the lakes and the dam, especially in dry seasons.
It separates farms from the park, gives people work and products (tea, wood) so they need less from the forest, and reduces fires, grazing and cutting at the forest edge.
Partly successful: four parks are protected, Gishwati-Mukura became a national park and Biosphere Reserve, burned areas and degraded landscapes are being restored, and local people share tourism revenue. But much natural vegetation was lost before protection (Gishwati 97.5%, Bugesera savannah), fires and illegal use continue, and new trees are mostly exotic plantations, not natural forest. A balanced conclusion: success in stopping losses inside protected areas, with continuing pressure outside them.

Quick check

Gishwati shrank from 28,000 ha in 1960 to about 700 ha in 2009. What percentage was lost?

Key points

Vegetation gives energy (86% of primary energy), income (forestry about 6% of GDP, tourism), water and soil protection, carbon storage, habitat and crafts.
Main causes of destruction: farmland and pasture, settlement, charcoal, fire, mining, bamboo cutting and poaching. Gishwati lost 97.5% between 1960 and 2009.
Effects: erosion and landslides, floods and low dry-season flows, siltation, lost wildlife and income, fuel shortage.
Conservation: parks and laws, the Gishwati-Mukura Biosphere Reserve (2020), revenue sharing, restoration (LAFREC, fern clearing), buffer zones, cookstoves and agroforestry, wetland protection.

1A forest that shrank by 97%

2Why vegetation matters

3Causes of vegetation destruction

4Effects of vegetation destruction

5Conserving vegetation in Rwanda

A forest that shrank by 97%

Why vegetation matters

Causes of vegetation destruction

Effects of vegetation destruction

Conserving vegetation in Rwanda