In January through February 1994, we conducted the first broad-scale survey of Guyanese primates since 1975. Our goals were (1) to follow up questions raised in the earlier survey, (2) to compare population densities, and (3) to locate potential sites for future long-term research. We used distributional survey methods along trails and rivers and interviewed local inhabitants in each region. We surveyed five general areas, two of which had been studied in 1975. The distribution reported in 1975 for five monkey species—Alouatta seniculus, Cebus olivaceus, Pithecia pithecia, Chiropotes satanas,and Saimiri sciureus—was confirmed. However, questions were raised concerning the western extent of the range of three species: Ateles paniscus, Cebus apella,and Saguinus midas.In comparing densities between 1994 and 1975, we found a significant drop in group densities over the past 20 years and a shift in relative proportions of individual primate species over time. For example, although the total number of kilometers surveyed was identical, group densities were three times higher in 1975 than in 1994. Further, group densities of Ateles, Alouatta,and Pitheciawere much lower, while those of Saguinuswere similar in both years. These findings strongly suggest that habitat destruction and continued hunting pressure are affecting the primate populations.

A survey of the distribution and density of the primates of Guyana

Quantitative measurements of changes in tropical biodiversity are sparse, despite wide agreement that maintaining biodiversity is a key conservation goal. Pan-tropical networks to systematically measure plot-level biodiversity are currently being developed to close this gap. We propose that a key component of such networks is the monitoring of human activities at broader scales around plots, to enable interpretation of biodiversity trends. This monitoring goal raises questions about the spatial extent and variables needed to capture interactions between human activities and biodiversity at multiple scales. We suggest a pragmatic approach to delineate and monitor a “zone of interaction” around biodiversity measurement sites to bridge across these scales. We identify the hydrologic, biological, and human interactions that connect local-scale measurements with broader-scale processes. We illustrate the concept with case studies in the Udzungwa Mountains in Tanzania and Ranomafana National Park in Madagascar; however, the framework applies to other biodiversity measurement sites and monitoring networks as well.

From plot to landscape scale: linking tropical biodiversity measurements across spatial scales

Protected areas are crucial for Amazonian nature conservation. Many Amazonian reserves have been selected systematically to achieve biodiversity representativeness. We review the role natural-scientific understanding has played in reserve selection, and evaluate the theoretical potential of the existing reserves to cover a complete sample of the species diversity of the Amazonian rainforest biome. In total, 108 reserves (604,832 km2) are treated as strictly protected and Amazonian; 87 of these can be seen as systematically selected to sample species diversity (75.3% of total area). Because direct knowledge on all species distributions is unavailable, surrogates have been used to select reserves: direct information on some species distributions (15 reserves, 14.8% of total area); species distribution patterns predicted on the basis of conceptual models, mainly the Pleistocene refuge hypothesis, (5/10.3%); environmental units (46/27.3%); or a combination of distribution patterns and environmental units (21/22.9%). None of these surrogates are reliable: direct information on species distributions is inadequate; the Pleistocene refuge hypothesis is highly controversial; and environmental classifications do not capture all relevant ecological variation, and their relevance for species distribution patterns is undocumented. Hence, Amazonian reserves cannot be safely assumed to capture all Amazonian species. To improve the situation, transparency and an active dialogue with the scientific community should be integral to conservation planning. We suggest that the best currently available approach for sampling Amazonian species diversity in reserve selection is to simultaneously inventory indicator plant species and climatic and geological conditions, and to combine field studies with remote sensing.

Amazonian biodiversity and protected areas: do they meet?

Eastern Amazonia is defined here as the region to the east of the Rio Xingu, including the Marajo archipelago in the Amazon delta (Figure 1). This region’s habitats can be divided into three main types: lowland and submontane tropical rainforest (terra firme), flooded forests (including mangrove, varzea and igapo) and cerrado (savanna). A fourth major category that is becoming increasingly dominant encompasses disturbed and secondary forest, and land cleared for agriculture (SUDAM, 1988). In some areas, such as the 30,000 km2 Zona Bragantina to the east of Belem, the original cover is now virtually nonexistent (Johns and Ayres, 1987; Salomao, 1994), while a large part of the lowland forest between the Xingu and the Tocantins remains intact.

Primate Populations in Eastern Amazonia

Comparison of Plant Diversity and Phenology of Riverine and Mangrove Forests with Those of the Dryland Forest in Sabah, Borneo, Malaysia

Suriname is a small country, but it still has large tracts of undisturbed forests and rich wildlife. The authors discuss Suriname's plans to extend its already excellent network of protected areas and proposals to amend the hunting regulations. They also consider the country's eight monkey species, whose status can be regarded as indicative of that of the rest of the country's wildlife.

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Ferdinand L. J. Baal

Papers

Primates and protected areas in Suriname