THE WORLD CONFERENCE ON ECOLOGICAL RESTORATION

2005 The World Conference on Ecological Restoration 29
Lanscape restoration of marginal olive groves in Andalusia
Arriaza M.,O. Nekhay
Dpt. of Agricultural Economics. IFAPA. Spain
Due to the reform of the olive oil MCO some olive groves in mountain areas will become non-productive.
The abandonment of these cultivated lands will have an effect on several landscape sustainability criteria:
biodiversity, soil erosion, fire hazard and visual quality of the rural scene. The first phase of this
three years research project has been to devise a marginality index for olive cultivation based on soil
quality and slope. According to this index, we estimate an area over 200,000 hectares of marginal olive
plantations in Andalusia. Some corrective measures in the area of study, the mountain areas of the
province of Cordoba, are explored to minimize the negative impact of this abandonment, being the use of
grass cover in the olive plantation, the connection of olive groves with natural protected areas via green
corridors and the integration of buildings through vegetation the most positive.
Keywords: land abandonment, olive groves, biodiversity, soil erosion, fire hazard and visual quality.
Effects of restoring oak savannas on tree water uptake dynamics in the tallgrass
prairie region of the Midwest, USA
Asbjornsen H. 1 , M. Gómez-Cárdenas 1 , L. Brudvig 1
1 Department of Natural Resource Ecology and Management, Iowa State University, 234 Science II, Ames, IA, 50010, USA
Conversion of native savanna and prairie ecosystems to annual cropping systems in the Midwestern U.S.
has dramatically altered hydrologic functioning, leading to increased runoff, soil erosion and nutrient
loss. One approach to reversing this trend is restoration of native ecosystems. However, little is known
about the effects of restoration on plant-water dynamics. This study examined changes in individual tree
and stand scale water uptake in encroached and restored savanna ecosystems. Sapflow was measured
using thermal dissipation probes for 3 Quercus macrocarpa and 4 Ulmus americana trees in an encroached
savanna and 3 Q. macrocarpa trees in a restored savanna. Mean total daily transpiration for
trees was 3 - 4.8-fold lower for U. americana compared to Q. macrocarpa, while sapflow among oak trees
did not differ significantly. In contrast, sapflow velocity was significantly greater for elm trees compared
to oak trees, likely a result of their young age and vigorous growth. On an ecosystem scale, estimated
total amounts of water transpired were more than 7-fold greater in the encroached savanna relative to
the restored savanna. These results suggest that oak trees in these restored savanna ecosystems are not
moisture limited. Since forests may sustain much greater total water uptake, savanna restorations may
not be desirable if a central management goal is to reduce runoff. Further research is needed on water
uptake capacities of the herbaceous understory and effects of tree-grass interactions on resource partitioning,
runoff, and infiltration dynamics in restored savannas to better understand changes in hydrologic
functioning following savanna restorations.
Keywords: tallgrass oak savanna, restoration, sapflow, transpiration, plant-water cycling.
Ecological diversity and productivity of the baobab (Adansonia digitata) in
Benin
Assogbadjo 1 A.E., B. Sinsin 1 , P. Van Damme 3
1 Laboratory of Applied Ecology, Faculty of Agronomic Sciences, University of Abomey-Calavi, Benin
2 Laboratory of Tropical and Subtropical Agriculture and Ethnobotany, University of Gent, Belgium
This study was carried out in the Sudanian (9°45' - 12° N), Sudano-Guinean (7°30' - 9°45' N) and
Guinean (6°25' - 7°30' N) zones of Benin. The objective of this study is to evaluate the ecological diversity
in Benin of A. digitata populations across the climatic gradient, and to quantify the average productivity
of its pulp, seeds, kernel. The distribution and relative abundance of the baobab was studied by means
of megatransects and by surveying a number of selected sites. In each zone, an estimate was made of
pulp, seeds and kernel production from 1200 fruits harvested from 30 individuals. In the Sudanian zone
and in some regions of the Dahomey-Gap in the Guinean zone, a population density of 5 baobabs was
recorded per km 2 . In the Guinean zone, a density of only 1 baobab per km 2 was recorded. The baobab
population’s occurred on sandy soils in the Sudanian and Guinean zones and on sandy–clayey soils in
the Sudano-Guinean zone. Flowering and fruiting of the baobab is seasonal. The morphology and productivity
of the individuals’ baobabs varied significantly from one zone to another. The zones with high
values of Potential Evaporation, rainfall, relative humidity, temperature, pHwater and percentage of fine
silt are associated with a low seed and fruit pulp production. The higher the pH kcl
, the percentage of total
nitrogen, organic carbon and organic matter, the higher the number of seeds produced by an individual