Patrick Lavelle - Academia.edu (original) (raw)

Papers by Patrick Lavelle

Biology and Fertility of Soils, 2008

Despite the impact of soil millipedes on litter fragmentation in tropical forests, there have bee... more Despite the impact of soil millipedes on litter fragmentation in tropical forests, there have been few studies dealing with factors determining their habitat preference in these ecosystems. In a natural secondary dry forest of Guadeloupe on Leptosol, two complementary studies were carried out in order to test the hypothesis that litter N-content strongly influences millipede distribution. Millipede abundance and species richness were described in the field under two tree species, Bursera simaruba and Pisonia subcordata, and were related to the chemical characteristics of their foliage. In addition, a laboratory experiment was done in order to assess millipede feeding preferences regarding the chemical characteristics of leaves from various species. Millipede abundance and species richness were significantly higher under P. subcordata than under B. simaruba, probably due to the higher N content of P. subcordata leaves. Moreover, millipedes fed preferentially on N-rich leaves. The present study confirms that there was a close correlation between the preferred food, its chemical composition and the local distribution of millipede populations.

A central question of the Diversitas program, Brasilia (1993), was how the reduction of biodivers... more A central question of the Diversitas program, Brasilia (1993), was how the reduction of biodiversity, or more precisely species richness in a given ecosystem, will affect the processes characterizing its functioning in those aspects related to energy and matter flow, to reproduction and perpetuation in time, and to resistance and resilience in the face of disturbances of variable intensities. Savannas are the most widespread ecosystem in the tropics and as such are subjected to great human pressure that may result in massive soil degradation. The book addresses the role of species in the function of savanna ecosystems. It is shown that savannas are enormously diverse and that four factors determine the function of savanna ecosystems: Plant Available Moisture; Plant Available Nutrients; Fire; Herbivores.

Applied Soil Ecology, 1998

The soil macrofaunal communities (Lumbricidae, Formicidae, Coleoptera, Chilopoda, Diplopoda, Isop... more The soil macrofaunal communities (Lumbricidae, Formicidae, Coleoptera, Chilopoda, Diplopoda, Isopoda, Arachnida, Gastropoda) were studied in six plots representing different stages in a theoretical post-pastoral succession on chalk grassland. Macrofaunal biomass was high in all the plots (70.2±140.3 g m À2 ). The macroinvertebrate communities along successional gradients respond to two major environmental factors: the structure of the vegetation, which determines the diversity of microhabitats and life conditions for macroinvertebrates; and the quality of above-ground litter production, which depends on the nature of vegetation and the presence of domestic herbivores. # 1998 Elsevier Science B.V.

European Journal of Soil Biology, 2000

Inoculation of Pontoscolex corethrurus (Glossoscolecidae, Oligochaeta) in a Peruvian ultisol unde... more Inoculation of Pontoscolex corethrurus (Glossoscolecidae, Oligochaeta) in a Peruvian ultisol under several treatments (without or with organic input) has been previously shown to increase macroaggregation and bulk density and to decrease water infiltration and soil moisture. In the present study, we used image analysis of thin sections of soil to understand the impact of earthworm on the structure of the upper layer of the soil. Morphological analysis allowed to quantify the abundance of casts, soil compactness, pore morphology and connections between different pore classes. This approach was applied to experiments carried out at Yurimaguas (Peru), in four plots. Two of them had been inoculated with Pontoscolex corethrurus. In each case, one control plot was conducted without organic input, the other with crop residues and legume green manure. Morphological parameters were measured in fourteen horizontal sections within the first 3 cm. They showed compaction of soil surface due to cast coalescence in plots with earthworms but without organic input and illustrated the typical crumb structure induced by earthworms in plots with organic input. © 2000 Éditions scientifiques et médicales Elsevier SAS image analysis / earthworm / Pontoscolex corethrurus / casts / soil structure / organic input / soil compactness

Applied Soil Ecology, 2004

Eight soil samples were taken along a gradient of metal contamination, from a heavy metals contam... more Eight soil samples were taken along a gradient of metal contamination, from a heavy metals contaminated pasture that was polluted by the disposal of wastes of metallurgic industry that occurred 70 years ago. The concentrations of heavy metals (Zn, Cd, Pb and Cu) were estimated by total contents and DTPA-extractions. The total contents of the heavy metals ranged from 108 to 1231 mg Zn kg −1 , 2.5 to 5.2 mg Cd kg −1 , 31 to 466 mg Pb kg −1 and 33.5 to 107.5 mg Cu kg −1 . The DTPA extractable fractions were highly correlated with the total contents of metals in the soils. Therefore, total metal contents and DTPA extractable fractions both presented similar correlations with the physico-chemical and biological characteristics of soils. Organic C, total N, microbial biomass C and N, ranged from 19.7 to 72.3 g C kg −1 , 0.9 to 5.4 g N kg −1 , 197 to 1230 mg C kg −1 and 62 to 122 mg N kg −1 . They were positively correlated with the metal content of the soils, while the ratio of biomass C/organic C, which varied from 1.28 to 1.82%, was unaffected by heavy metal contamination. The ratios of biomass C/biomass N, which ranged from 3.2 to 10.3%, were highly positively correlated with soil metal contents, indicating variation in the microbial community in relation to contamination. On the other hand, microbial activities such as respiratory intensity, specific respiration, the respiration rate, net N mineralisation and the intensity of net N mineralisation of biomass N, which varied from 19.3 to 54.7 mg C-CO 2 g −1 organic C, 0.02 to 0.24 mg C-CO 2 mg −1 C biomass, 2.4 to 8.9 mg C-CO 2 g −1 organic C per day, 15 to 46 mg N mineralised mg −1 total N, 0.13 to 0.88 mg N mineralised mg −1 N biomass, were all negatively correlated with the heavy metal contents of the soils.

Soil Biology & Biochemistry, 2004

c Laboratoire des interactions micro-organismes-minéraux-matières organiques dans les sols (LiMos... more c Laboratoire des interactions micro-organismes-minéraux-matières organiques dans les sols (LiMos), FRE 2440 du CNRS, associée à l'Université Henri

European Journal of Soil Biology, 2002

In the north of France, a century of industrial metallurgic activities produced significant heavy... more In the north of France, a century of industrial metallurgic activities produced significant heavy metal soil pollution. In the north of France zinc smelter waste created a gradient of zinc concentration from 171 to 19 000 ppm in 35 m. The aim of this study was to evaluate the effects of soil pollution on the composition, density and diversity of macrofauna communities. The results showed that heavy metals reduce the overall density of earthworms and other macrofauna populations. The composition of the macrofauna community changed with the degree of pollution. There was no simple relationship between soil zinc content and species richness. In polluted areas, the number of species could be lower, equal or higher than in unpolluted zones. Increase of species richness in some polluted zones was due to the settlement of tolerant arthropod taxa. Coleoptera and some Arachnida were possibly favoured by the litter accumulation resulting from the reduced population densities of earthworms and other decomposers.

Soil Biology & Biochemistry, 2005

Near infrared reflectance spectroscopy (NIRS) analysis was used to discriminate soils of differen... more Near infrared reflectance spectroscopy (NIRS) analysis was used to discriminate soils of different agroecosystems in Colombia, with different contents and qualities of organic matter, chemical, and biological properties.

Pedobiologia, 2000

D Di if ff fe er re en nc ce es s i in n t th he e t ti im mi in ng g o of f d di ia ap pa au us ... more D Di if ff fe er re en nc ce es s i in n t th he e t ti im mi in ng g o of f d di ia ap pa au us se e a an nd d p pa at tt te er rn ns s o of f a ae es st ti iv va at ti io on n i in n t tr ro op pi ic ca al l e ea ar rt th hw wo or rm ms s et al.

Soil Science Society of America Journal, 1996

Biology and Fertility of Soils, 1992

Mineral N concentrations ranged from 133.1 to 167.8 μg g-1 dry soil in fresh casts of the endogei... more Mineral N concentrations ranged from 133.1 to 167.8 μg g-1 dry soil in fresh casts of the endogeic earthworm Pontoscolex corethrurus fed on an Amazonian Ultisol; this was approximately five times the concentration in non-ingested soil. Most of this N was in the form of NH inf4sup+. N also accumulated in microbial biomass, which increased from a control value of 10.5–11.3 to 67.5–74.1 μg g-1 in fresh casts. During a 16-day incubation, part of the NH inf4sup+-N was nitrified and/or transferred to the microbial biomass. Total labile N (i.e., mineral+biomas N) decreased sharply at first (ca. 50% in the first 12 h), and then more slowly. The exact fate of this N (microbial metabolites, denitrification, or volatilization) is not known. After 16 days, the overall N content of the casts was still 28% higher than that of the control soil. Incubation of the soil before ingestion by the earthworms significantly increased the production of NH inf4sup+in casts. We calculate that in a humid tropical pasture, 50–100 kg mineral N may be produced annually in earthworm casts. Part of this N may be conserved in the compact structure of the cast where the cast is not in close contact with plant roots.

Biology and Fertility of Soils, 2002

Agroforestry systems are presented as a valuable alternative to pastures to sustain crop producti... more Agroforestry systems are presented as a valuable alternative to pastures to sustain crop production in forested areas. In order to evaluate their effect on soil macroinvertebrate communities, sampling was conducted during the rainy season at four localities located in the Rondônia and Acre states of Brazil. Four land-use systems were selected (fallow, annual crop, agroforestry systems and pasture), and compared to nearby disturbed forests. We used the sampling method recommended by the Tropical Soil Biology and Fertility Programme. Soil macrofauna responded more readily than soil parameters to different cultivation practices. Co-inertia analysis, however, showed a relationship between soil parameters and soil macrofauna. Comparison of communities showed a significant impact of land-use practices. All systems had quite abundant invertebrate communities with relatively low densities in the forest (884 ind. m–2) and in pastures (841 ind. m–2), and higher densities in fallow, agroforestry system and annual crop (1,737–1,761 ind. m–2). Earthworms were dominant in pastures (155 ind. m–2 and 56.2 g m–2 on average), whereas termites thrived better in annual crops and fallows (with respective densities of 1,287 and 816 and biomasses of 2.32 and 1.38 g m–2). Macrofauna communities in agroforestry systems were rather similar to the forest, in spite of higher densities of social insects. The termite:earthworm ratios were very low in pastures (0.2), had similar values in the forest (7.9) and the agroforestry system (8.8), which is much lower than in fallows (20.4) and annual crops (21.4) This study showed that all land-use practices were able to sustain sizeable macrofaunal communities with agroforestry communities rather similar to the those of a disturbed forest.

Decomposition processes in tropical semi-evergreen forests are still poorly understood. The influ... more Decomposition processes in tropical semi-evergreen forests are still poorly understood. The influence of soil properties and litter quality on decomposition rate was studied in two semi-evergreen forests of Guadeloupe, a forest plantation and a secondary forest, located on different soils. Leaf litter of four tree species was enclosed in litterbags for a 14-month period. Non-linear correlations were calculated between mass loss and the concentration of major leaf components (soluble C, N, lignin, cellulose, tannins, total soluble phenols) in order to determine the best predictor of leaf litter decomposition. Soil physico-chemical properties and ratios between some of the above-mentioned litter quality parameters were also examined as mass loss predictors. In addition, non-linear correlations were calculated between mass loss and litter quality parameters, at successive periods. Litter quality was the main determinant of litter decomposition in the studied forests. Several litter quality parameters were correlated with leaf disappearance, varying according to stages of decomposition. Between 1 month and 2.5 months, the mass loss was correlated negatively with the initial phenol content and with initial lignin:N and (lignin+phenol):N ratios. From 2.5 to 5.5 months, the mass loss was correlated negatively with the initial phenol content and positively with the initial cellulose content. At later stages of decomposition (9–14 months), the mass loss was correlated negatively with the initial tannin content. Differences in soil characteristics and fauna did not seem to be enough to affect decomposition.

Soil Biology & Biochemistry, 1997

In a study of a 15-year-old pasture in Martinique (French West Indies), abundance and organizatio... more In a study of a 15-year-old pasture in Martinique (French West Indies), abundance and organization of microarthropod communities were correlated with the spatial distribution of the earthworm Polypheretima elongata (Megascolecidae). In patches of high earthworm density (133 individuals m–2), microarthropod density was significantly higher (80000 individuals m–2) than in patches with few earthworms (31 worms m–2 and 49000 microarthropods m–2). The diversity of microarthropod communities followed a similar pattern, the Shannon index for Collembola communities being, respectively, 3.12 and 1.82 in and outside earthworm patches. These results suggest that mesofauna abundance and diversity might be at least partly determined by the activity of larger invertebrates, as a result of the dramatic effects that the latter group exerts upon soil structure, pore distribution and food resources.

Applied Soil Ecology, 1999

Earthworms are known to modify life conditions for other soil organisms through their drilospheri... more Earthworms are known to modify life conditions for other soil organisms through their drilospheric activities. The effects of a large anecic species, Martiodrilus carimaguensis Jime Ânez and Moreno, on soil macrofaunal communities were investigated in a natural and a man-made grassland of the Eastern Plains of Colombia. Invertebrates were sampled by a standard hand sorting method at different spatial scales: (i) at the scale of a few centimetres during the course of one year, we compared the dynamics of the density, biomass, diversity and individual weights of macroinvertebrates in earthworm surface casts, in the soil located below casts and in a control soil without casts;

The influence of human activities on soil arthropods of vertisols was assessed in several plots c... more The influence of human activities on soil arthropods of vertisols was assessed in several plots characterized by different land uses in the south-eastern part of Martinique (French West Indies). Abundance and diversity of soil invertebrate groups and collembolan species were measured in a 40-year-old secondary forest, a 15year-old fallow, a 4-year-old fallow, a 4-year-old pasture, a 15year-old pasture and a 20-year-old market-garden. Agricultural practices modified abundance and species distribution of soil arthropods, compared to forest. Arthropod richness (number of taxa present) decreased from forest to market-garden, according to a gradient of intensification of agricultural use (pesticides, tillage, weed control). In the old pasture, the arthropod diversity was lower in spite of a high carbon content. Species richness of Collembola decreased together with plant diversity and water availability. 0 1999 Editions scientifiques et medicales Elsevier SAS Soil arthropods / Collembola / agricultural practices / biodiversity R&urn6 -Influence des pratiques agricoles sur les communautks d'arthropodes dans un vertisol (Martinique).

Nutrient Cycling in Agroecosystems, 2001

This paper synthesises information on the food requirements of soil macroinvertebrates and some o... more This paper synthesises information on the food requirements of soil macroinvertebrates and some of their effects on soil organic matter dynamics. Some clues to techniques that would optimise their activities through organic matter management are suggested. Soil macroinvertebrates can consume almost any kind of organic residues in mutualistic association with soil microflora. Significant amounts estimated at several T per ha of predominantly easily assimilable C are used yearly in natural ecosystems as energy to sustain these activities. Sources of C used are highly variable depending on the feeding regime. The largest part of the energy assimilated (e.g., 50% by the tropical earthworm Millsonia anomala) is actually spent in burrowing and soil transport and mixing. Bioturbation often affects several thousand tons of soil per hectare per year and several tenth of m3 of voids are created in soil. A great diversity of biogenic structures accumulate and their nature and persistance over time largely controls hydraulic soil properties. The OM integrated into the compact biogenic structures (termite mounds, earthworm globular casts) is often protected from further decomposition. Most management practices have negative effects on the diversity and abundance of macroinvertebrate communities. Structures inherited from faunal activities may persist for some weeks to years and the relationship between their disappearance and soil degradation is rarely acknowledged. When SOM supply is maintained but diversity is not, the accumulation in excess of structures of one single category may have destructive effects on soil. It is therefore essential to design practices that provide the adequate organic sources to sustain the activity and diversity of invertebrates. Special attention should also be paid to the spatial array of plots and rotations in time.