Effects of Human Activities on Ecosystems and Environmental Conservation
Senior 3 · Biology
Effects of Human Activities on Ecosystems and Environmental Conservation
Lesson 5 of 5
25 min
In 2004 Rwanda had serious power cuts. Much of the country's electricity then came from the Ntaruka and Mukungwa hydropower stations, which run on water from Lakes Burera and Ruhondo. Those lakes are fed by the Rugezi marsh, high in the north near the border with Uganda. Parts of the marsh had been dug with drainage canals for farming, and in 2000 more drainage was done. With a drier marsh and years of low rainfall, less water reached the lakes: by 2004 their water levels had fallen to half their average depth of 1957–1970. The power stations had to cut production, and the country ran diesel generators costing up to US$65,000 a day. A wetland that most people had never visited turned out to be keeping the lights on. This lesson looks at three conservation programmes in Rwanda and what they achieved.
Definition
Conservation programme: an organised, long-term plan to protect or restore species and ecosystems.
Ecological restoration: helping a damaged ecosystem to recover, for example by replanting native trees or blocking drainage canals.
Ecosystem services: the benefits people get from ecosystems, such as clean water, stable soils, pollination, fish, timber, tourism and the storage of carbon.
Wetland: land that is covered by shallow water or waterlogged for all or part of the year, such as a marsh or swamp.
Buffer zone: a strip of land around a protected area or along a river or lake where land use is limited, to protect the core.
The Rugezi marsh lies in a flooded valley at 2,050 m in Burera and Gicumbi districts. In 2005 the Rugezi–Burera–Ruhondo wetland (6,736 ha) was designated a Wetland of International Importance under the Ramsar Convention on Wetlands. It is a headwater of the Kagera and Nile river systems and home to endangered birds, including the grey crowned crane and Grauer's swamp warbler.
Figure 1: Cause and effect at Rugezi: damage, then restoration.
What was done. The government stopped the drainage and banned farming and grazing in the wetland and along the shores of Lakes Burera and Ruhondo, using the environment and land laws of 2005, which require farming to stay back from the banks of rivers and lakes. In 2008 Rugezi was declared a protected area. Farmers who lost land were helped with other ways of earning a living.
Results. The water returned, and the Ntaruka power station went back to full operation. The Ramsar Convention records that drainage was halted and that the successful restoration won international recognition, including a Green Globe Award in 2010.
Worked example 1: the cost of losing a wetland
Diesel generators cost Rwanda up to US$65,000 a day during the electricity crisis. (a) What would this cost in one year at the full rate? (b) After how many days at the full rate would the cost pass US$10 million?
Lesson: the "free" service of a wetland, storing water and releasing it slowly, can be worth millions of dollars a year. Draining it for a few hectares of farmland was a very poor exchange.
In Lesson 2 you saw how the Gishwati forest shrank to about 600 hectares by 2005. Restoration then began:
The national report to the FAO states that the restoration work has helped to stop the floods and landslides, control erosion and reduce the silting of streams and marshes.
Worked example 2: how much forest came back?
Use the figures above: 600 ha of natural forest in 2005, 286 ha added by PAFOR and 598 ha reforested by the conservation programme. (a) Check that these give about 1,484 ha. (b) Calculate the percentage increase from 2005.
Interpretation: the forest area grew to almost two and a half times its 2005 size, but it is still a small fraction of the forest that stood in the 1970s (about 28,000 ha). Restoration is possible, but it is slow and never fully replaces what was lost.
Umuganda, community work, is set out in Law N° 53 of 2007: it takes place on the last Saturday of every month, starting at 8 a.m. and lasting at least three hours, and every Rwandan from 18 to 65 years old who is able to work takes part. Much of the work protects the environment: planting trees, cleaning streets and drains, cutting grass and clearing bushes, and restoring wetlands, as in the photo below. The Ministry of Environment reports that umuganda has given citizens the chance to plant trees and increase forest cover, and that Rwandans planted 25 million trees in the 2020–2021 planting season.
Worked example 3: the work of one sector
A sector has 12,000 residents aged 18 to 65 who are able to work. Each takes part in umuganda for 3 hours a month. (Illustrative figures.) (a) How many hours of work is that in a year? (b) If one person can plant 20 tree seedlings in an hour, how many seedlings could be planted in one 3-hour umuganda if all the sector's workers planted trees?
| Benefit | Example from this unit |
|---|---|
| Water and energy | Rugezi stores water for Lakes Burera and Ruhondo and their power stations; forests feed rivers and springs |
| Safety | restored Gishwati slopes have fewer floods and landslides |
| Soil and farming | trees, terraces and grass strips hold soil and keep streams clear of silt |
| Biodiversity | habitats for gorillas, chimpanzees, golden monkeys, cranes and many other species |
| Climate | forests and wetlands store carbon (Unit 3) |
| Income and jobs | tourism, with 10% of park tourism revenue shared with neighbouring communities |
| A cleaner country | umuganda and the ban on plastic bags keep streets, drains and waterways clean |
Warning
Common mistakes. (1) Thinking conservation means "no people allowed": successful programmes involve local communities and give them benefits. (2) Believing that a restored ecosystem is as good as the original: restoration takes decades and some species may never return. (3) Quoting a figure without its source and year, as in "the forest is now 1,484 ha": say who reported it and when.
Kwita Izina 2021: Gishwati-Mukura National Park, a story of community-led conservation (Visit Rwanda). Watch for the ways people living around the park take part in protecting and restoring it.
Tip
Exam technique: case studies. For a conservation case study give: the place, the problem (with a cause), what was done, and the results (with one number). Rugezi, Gishwati–Mukura and umuganda are three ready-made examples.
Practice: conservation programmes
Key points
Further reading for this unit
Sources and credits
Written by Ganzaa: Figure 1, the benefits table, the worked examples and the practice questions.
