Policy
ESP Journal
CH4.org.uk
Oxford Environment
UKERC
UKCIP

Oxford Centre for
Water Research

Sustainable Forest Resource Management
For Biodiversity Protection in Madagascar

Investigators:

Jane Carter Ingram, Scott Henderson, and Dr. Terry Dawson
Environmental Change Institute, Oxford University,

Collaborators:

Manon Vincelette, QMM S.A., Madagascar
Dr. Paul Smith, Royal Botanic Gardens, Kew, London
Dr. Robert Whittaker, Department of Geography, University of Oxford
Dr. Stephen Cobb, Environment and Development Group, Oxford

Context and Geographical Setting:
The flora and vegetation of Madagascar have attracted the interest of botanists for well over a century, and have captured the imagination of naturalists from throughout the world. This island nation, located off the southeastern coast of Africa , is widely regarded as one of the world's most fascinating centers of plant diversity and endemism. It is also home to some of the most highly threatened habitats on Earth, and increasingly is being recognized as a priority area for conservation activities (Sussman, 1994; Dumetz, 1999). Madagascar (size ca. 587,000 km²) has a remarkable array of vegetation types, ranging from humid tropical forests, where average annual precipitation exceeds 3,500 mm, to arid semi-deserts that receive less than 350 mm of rainfall per year.

The native flora is exceptionally rich, although no one knows with certainty how many plants occur on Madagascar, and recent estimates range from 8,500 species (White, 1983) to 10,000 (Humbert, 1959; Phillipson, 1994) or even 12,000 species (Dejardin et al., 1973), of which anywhere from perhaps 70% to 80% or more are endemic (Humbert, 1959).

Despite its size Madagascar's population is only 13.9 million people with over 80% still living in rural areas and the island has been classified as one of the 15 poorest nations in the world (USAID, 1999).

Development Issues:
In 1986, QMM, a subsidiary of the mining company Rio Tinto, discovered three ore-bodies of heavy minerals in the Mandena, Ste-Luce and Petriky regions near Tolagnaro (Fort-Dauphin) in south-eastern Madagascar (QMM, 1998)(Figure 1 and 2). The heavy minerals are a source of titanium dioxide, which has many modern industrial applications. These mineral deposits are covered by a range of coastal vegetation types, the most interesting of which occurs as remnants of littoral forest.

As a result of the potential impacts of mining in the region, a number of biodiversity studies undertaken over the 1989-1992 period revealed a series of remnant stands and forest fragments, covering approximately 4,000 ha throughout the region. It is thought that this vegetation type once covered most of the coastal lowlands of eastern Madagascar. However, these stands have all been modified to some extent by human activities, but they are considered important as they are the remaining representatives of a diverse community type, much of which has been degraded or removed elsewhere in Madagascar through over-exploitation. In addition, the swamp and marshes in the area form an important habitat for avi-fauna and amphibians.

Figure 3. Land Change in Southeastern Madagascar


Figure 4. Gathering wood for fuel

(photos courtesy of http://www.williams.edu/CES/faculty/klee/Madagascar/TripRept_hm.html)

Remote Sensing:
The development of extensive spatial data on forest cover, plant species distributions and vegetation types provides us with a framework for: (a) assessing our current knowledge and location at regional scales, and (b) stratifying the biological landscape so that higher-resolution surveys can be more efficiently implemented (covering, for example, population abundance, reproductive success, and genetic dynamics). In an effort to better understand the environmental context within the study region, QMM commissioned MIR Télédétection Inc to quantify the extent and rate of deforestation within this region during the last few decades (MIR Télédétection Inc, 1998).

Deforestation coverage was estimated at the regional scale, on a 20 km width corridor from the coast, through the analysis of digital spaceborne 1972 Landsat MSS, 1984 and 1992 Landsat TM and 1995 Panchromatic SPOT data (Figure 5). The results obtained indicate that the regional forest cover has been in a continuous state of decline since 1972, with an annual average rate of deforestation of 760 hectares.

By means of standard photo-interpretation methods using 1950, 1974 and 1989 aerial photographs, and the 1995 Panchromatic SPOT data, a more detailed analysis of the forest cover within the Fort-Dauphin exploration zone was undertaken. The results obtained show that approximately 3400 hectares of littoral forest within the Fort-Dauphin exploration zone has disappeared between 1950 and 1995, leaving approximately 3700 hectares of littoral forest in 1995 (Figure 6). This deforestation was more significant within the Mandena and Petriky zones closest to the centres of human settlements.

Building upon this research, using a combination of fieldwork, remote sensing and Geographical Information Systems (GIS), we intend to develop a series of thematic maps of: (a) existing natural or semi-natural land cover to the level of community alliances (vegetation types characterized according to their dominant or co-dominant plant species or, in the absence of a dominant vegetation species, dominant land cover feature; and (b) predicted distributions of endemic species. These data layers will be analysed to compare distributions of each native species, group of species, and community alliance with the existing network of conservation regions. Results will reveal where the conservation gaps are in both land management and in the body of knowledge about species and natural communities.

Fieldwork monitoring of forest fragments:
Preliminary fieldwork conducted in the Mandena sub-region during the 1999 summer campaign explored one structural criterion, intactness, and how it related to floristic composition across three levels of forest degradation: minimally degraded (intact), moderately and highly degraded. A total of 3139 vascular plants were identified and 460 hardwoods were measured, identified, and tagged in nine 0.10 ha. Plots (Stohlgren, 1995) and nine variable-area transects, respectively (Henderson, 1999).

Comparison of the presence of species of special conservation interest using a subgroup of range-restricted endemics showed significantly different numbers of individuals in the three degradation levels (p<0.05). The intact forest fragments had more than double the number of individuals of priority species (those species identified as either locally or regionally endemic to the littoral forests) than the highly degraded forest and being the only degradation level found to have all nine priority species (Table 1). Likewise, from the plot analysis, the most degraded forest had significantly fewer individuals than lesser degraded forest of sixteen priority species investigated (p<0.05), whilst the most intact forest had the greatest number of priority species (15 species). Species richness in plots was found to be highest in the moderately degraded forest (n = 100), followed by the highly degraded forest (n = 90) with the most intact area returning the lowest score of the three levels (n = 89). In the transects, intact forest was found consistently to have the highest species richness in all size classes measured but the results were not significant. The degraded forest area was found to be greatly impoverished in the larger size classes of hardwoods compared to intact forest having, within the same area, 73% fewer species in the largest size class recorded (>15cm dbh). This result brings to question long-term regenerative potential if the smaller size classes are not allowed to reach maturity due to ongoing selective logging.

Diversity indices and species abundance model analysis returned ambiguous and generally insignificant results, but with some interesting trends. Initially, only the Berger-Parker index and Q statistic suggested that intact forest was more diverse, while seven others indicated that the more degraded areas were at least marginally more diverse (Henderson, 1999). However, removal from the data of one rarely encountered, but patchily hyper-abundant species found in two 1 m² subplots resulted in the most intact block’s showing higher diversity in seven of the nine indices- revealing as much about the limitations of the indices as the forests they attempt to describe. Given this index sensitivity and assuming that the intact forest has other merits to recommend its protection, this finding suggests that diversity indices may not always correlate with conservation interests, although they are commonly used in site assessment.

The combination of considerable abundance and the highest number of priority conservation species for the most intact block is an indication of meaningful diversity and an important qualitative difference from the other two degradation levels. Noteworthy is the result that in both the transects and the plots, the most degraded forest has the fewest individuals of conservation interest, although the number of priority species is not low. Likewise, particularly encouraging, from a conservationist perspective is the moderately degraded forest’s having many individuals, as well as a large percentage of the total number of priority species.

Discussion and Conclusion:
Extensive analysis of aerial photographs extending back to 1950 and satellite imagery from 1995 supported by ground validation over several field campaigns indicate over half of the littoral forest has completely disappeared, whilst remaining forest fragments are becoming significantly degraded. However, the most recent fieldwork monitoring reported in this paper has demonstrated that even the most degraded forest blocks retain a floral species richness and diversity, as measured by a variety of diversity indices and model fits, comparable, albeit generally more impoverished, to the most intact areas.

The next stage of the research is to undertake a visible and infrared remote sensing survey of the study area using aerial digital videography providing us with a high-resolution spatially-explicit database of land-cover and vegetation type. Predicting species distributions by relating them to environmental features that can be mapped from remotely sensed data is an efficient method to estimating the distribution and management status of elements of biodiversity in this region of Masdagascar. This approach can significantly contribute to identifying potential conservation zones in a way that is useful for the Malagasy Government in land-use planning and management, and to maintain their natural biodiversity and the processes that sustain it.

Project Links:
Six month report
Trip report 2000
Plants database

Acknowledgements
The authors would like to acknowledge the help and support of Daniel Lambert (QMM Montréal) Jean-Pierre Revéret (University of Québec, Montréal), Laurent Randrihasipara, Jean Baptiste Ramanamanjato, Ramisy Edmond, Vola Romaine, Claude Herysoanary, Delphin Tovoniaina, Germain Randriamandimby, Julson Geny, and Crescent Mosa (QMM Madagascar), Clive Hambler, Nick Brown, Martin Speight, Paul Johnson, Susan Canney and Peter Henderson (University of Oxford) Paul Smith (Royal Botanic Gardens, Kew), Pete Lowry (Missouri Botanical Garden) and Jorg Ganzhorn (University of Hamburg).

References
J. Dejardin, J.L. Guillaumet and G. Mangenot, "Contribution à la connaissance de l'élément non endémique de la flore malgache (végétaux vasculaires)", Candollea, 28, p.p. 325-391, 1973.

N. Dumetz, "High plant density of lowland rainforest vestiges in eastern Madagascar", Biodiversity and Conservation, 8, p.p. 273-315, 1999.

Henderson, S. J., Relationships Between Structure and Composition in the Littoral Forests of Southeast Madagascar, with particular reference to past degradation, unpublished M.Sc. thesis, University of Oxford, Oxford, 1999.

H. Humbert, "Origines présumées et affinités de la flore de Madagascar", Mém. Inst. Sci. Madag., sér. B, Biol. Vég., 9, p.p. 149-187, 1959.

MIR Télédétection inc, Étude sur la déforestation dans la région de Fort-Dauphin, Madagascar, QIT - Madagascar Minerals, Montréal, Canada, 1998.

P.B. Phillipson, " Madagascar", in S. D. Davis, V. H. Heywood and A. C. Hamilton (eds.), Centres of plant diversity. A guide and strategy for their conservation. Vol. 1., Europe, Africa, South West Asia and the Middle East, IUCN Publ. Unit, Cambridge, p.p. 271-281, 1994.

QMM, Project QMM: Social and Environmental Reports 1990-1992, QIT - Madagascar Minerals, Montréal, Canada, 1998.

T. Stohlgren, "A Modified Whittaker nested vegetation sampling method", Vegetatio, 117, p.p. 113-121, 1995.

R.W. Sussman, "Plant diversity and structural analysis of a tropical dry forest in southwestern Madagascar", Biotropica, 26(3), p.p. 241-254, 1994. 

USAID, United States Agency for International Development, http://www.info.usaid.gov/pubs/cp98/afr/ countries/mg.htm, 30 June, 1999.

F. White, "The vegetation of Africa, a descriptive memoir to accompany the UNESCO/AETFAT/UNSO vegetation map of Africa", UNESCO, Natural Resour. Res., 20, p.p. 1-356, 1983.

Related work:
Two related projects in Madagascar are being currently being conducted within the Biodiversity group by Carter Ingram and James Watson.