Earthworm Populations in Savannas of the Orinoco Basin. A Review of Studies in Long-Term Agricultural-Managed and Protected Ecosystems
Abstract
:1. Introduction
2. General Characteristics of the Studied Savannas
2.1. Soils of Trachypogon Savannas
Location | pH | Available P
(mg P kg−1 soil) | Total N
(mg N kg−1 soil) | Total C
(mg C kg−1 soil) | ∑Exchangeable bases
(cmol kg−1 soil) | Exchangeable aluminum
(cmol kg−1 soil) |
---|---|---|---|---|---|---|
Calabozo | 5.8 | 2.9 | 503 | 8,000 | 0.34 | 0.80 |
Puerto Ayacucho | 5.5 | 4.8 | 393 | 6,000 | 1.17 | - |
Uverito | 4.5 | 0.9 | 227 | 3,000 | 0.44 | 0.40 |
La Iguana | 5.2 | 4.0 | 320 | 7,000 | 1.06 | 0.90 |
Cabruta | 5.6 | 2.0 | 40 | 1,000 | 0.30 | 0.30 |
Carimagua- Colombia | 4.8 | 6.2 | 1450 | 23,000 | 0.45 | 2.42 |
2.2. Vegetation of Trachypogon Savannas
2.3. Agriculture Use in Trachypogon Savannas
2.4. Role of Macrofauna in Savannas
3. Supporting Case Studies
3.1. Earthworm Populations in a Savanna Organic Agroforestal System of the Venezuelan Amazonia
3.1.1. Changes in Earthworm Composition, Density and Biomass
Parameter | Locality | Depth (cm) | |||
---|---|---|---|---|---|
0-10 | 10-20 | 20-30 | 0-30 | ||
Density | OAFS | 145.6 | 8.0 | 1.6 | 155.2 |
NSA | 30.4 | 4.8 | - | 35.2 | |
Biomass | OAFS | 17.46 | 1.17 | 0.23 | 18.6 |
NSA | 0.65 | 0.44 | - | 1.09 | |
Density | PS | 38.4 | 25.6 | 0.0 | 64.0 |
NSC | 9.6 | 9.6 | 3.2 | 22.4 | |
Biomass | PS | 14.8 | 8.1 | 0.0 | 32.9 |
NSC | 2.6 | 1.1 | 1.4 | 5.1 |
3.1.2. Vertical Distribution
3.1.3. Horizontal Distribution
3.1.4. Age Distribution
3.1.5. Changes in Soil Quality Indices Induced by Organic Fertilization
Parameter | NS | OAFS |
---|---|---|
Total C (%) | 0.89 a | 1.45 b |
Total N (%) | 0.03 a | 0.12 b |
Total P (%) | 0.02 a | 0.05 b |
Microbial C (mgC kg−1) | 54.0 a | 106.0 b |
Microbial quotient (%) | 0.75 | 0.92 |
Microbial N (mgN kg−1) | 11.9 a | 22.1 b |
Microbial C/ Microbial N (%) | 4.54 | 4.80 |
Microbial P (mgP kg−1) | 4.4 a | 33.4 b |
Phosphatase Activity (mgP-NP kg−1h−1) | 10.7 a | 49.6 b |
Urease Activity (mg N-NH4 kg−1h−1) | 9.1 a | 12.1 b |
N-mineralization(µgg−1month−1) | 16.2 a | 23.4 b |
3.1.6. Correlations between Density and Biomass of Earthworms and Soil Parameters
Density | Biomass | Humidity | Temp | Sand | Clay | Silt | O. M. | pH | |
---|---|---|---|---|---|---|---|---|---|
Density | - | 0.81 * | 0.62 * | −0.16 | 0.33 | −0.36 | 0.01 | 0.52 * | 0.43 * |
Biomass | 0.69 * | - | 0.73 * | −0.03 | 0.35 | −0.35 | −0.04 | 0.63 * | 0.45 * |
Humidity | 0.65 * | 0.21 | - | −0.01 | 0.36 * | −0.47 * | 0.12 | 0.57 * | 0.31 |
Temp | 0.64 * | 0.21 | 0.99 * | - | −0.36 | 0.17 | 0.31 | 0.09 | −0.03 |
Sand | 0.54 * | 0.26 | 0.71 * | 0.68 * | - | −0.79 * | −0.41 * | 0.05 | −0.01 |
Clay | −0.41* | −0.16 | −0.63 * | −0.62 * | −0.89 * | - | −0.23 | −0.29 | −0.03 |
Silt | −0.48 * | −0.28 | −0.48 * | −0.42 * | −0.64 * | 0.23 | - | 0.35 | 0.07 |
O.M. | −0.22 | −0.06 | −0.35 | −0.33 | 0.08 | −0.09 | −0.01 | - | 0.45 * |
pH | −0.07 | −0.11 | −0.07 | −0.05 | 0.06 | −0.12 | 0.06 | −0.06 | - |
Locality | Dependent variable | Intercept | B | Adjusted R2 |
---|---|---|---|---|
OAFS | Density | −452.71 | 13.88 | 0.41 |
Biomass | −46.47 | 1.64 | 0.58 | |
NS | Density | −10.13 | 5.44 | 0.42 |
3.2. Earthworm Populations in a Long-Term Protected Savanna of Central Venezuela
3.2.1. Earthworm Composition, Density and Biomass
3.2.2. Vertical Distribution of Earthworms
3.2.3. Distribution by Classes of Stages of Development
3.2.4. Changes in Soil Quality Indices Induced by Long-Term Protection
3.2.4.1. Soil Physical Changes in Protected and Natural Savanna
3.2.4.2. Soil Chemical Changes in Protected and Natural Savanna
Parameter | Month | PS | NS | |||||
---|---|---|---|---|---|---|---|---|
Depth (cm) | Depth (cm) | |||||||
0-10 | 10-20 | 20-30 | 0-10 | 10-20 | 20-30 | |||
Temperature (ºC) | April | 29.2 (±0.57) a, D | 29.3 (±0.67) a, D | 30.3 (±1.48) b, D | 29.4 (±0.42) a, D | 29.4 (±0.55) a, D | 30.4 (±0.55) b, D | |
July | 25.30 (±0.27) a, D | 25.90 (±0.22) b, D | 26.30 (±0.27) b, D | 27.00 (±0.35) a, F | 27.60 (±0.55) ab, F | 28.00 (±0.35) b, F | ||
August | 25.90 (±0.65) a, D | 25.80 (±0.57) a, D | 26.50 (±0.27) a, D | 24.54 (±0.35) a, F | 24.50 (±0.50) a, F | 25.10 (±0.22) b, F | ||
Soil water content (%) | April | 2.31 (±1.77) a, D | 4.35 (±1.92) b, D | 5.29 (±1.16) b, D | 1.79 (±1.66) a, D | 4.56 (±1.08) b, D | 5.80 (±0.66) b, D | |
July | 14.35 (±1.77) a, D | 11.36 (±0.91) a, D | 10.01 (±2.66) b, D | 10.27 (±1.09) a, F | 9.04 (±1.77) a, D | 11.09 (±1.42) a, D | ||
August | 17.58 (±2.34) a, D | 15.80 (±1.11) a, D | 15.29 (±1.18) a, D | 13.14 (±1.94) a, F | 12.21 (±2.05) a, F | 11.97 (±1.02) a, F | ||
Sand (%) | April | 76.6 (±4.96) a, D | 71.7 (±4.70) a, D | 72.4 (±5.23) a, D | 79.6 (±2.24) a, D | 74.5 (±3.35) b, D | 71.6 (±4.00) b, D | |
Clay (%) | 12.1 (±4.61) a, D | 14.6 (±3.73) a, D | 14.6 (±3.36) a, D | 8.9 (±1.66) a, D | 13.6 (±2.25) b, D | 15.0 (±3.26) b, D | ||
Silt (%) | 11.3 (±6.43) a, D | 13.8 (±2.61) a, D | 13.0 (±3.18) a, D | 11.5 (±0.61) a, D | 11.9 (±1.24) a, D | 13.4 (±0.96) b, D | ||
Texture | FA | FA | FA | AF | FA | FA |
Parameter | PS | NS |
---|---|---|
pH | 6.00 a | 5.75 b |
Total C (mg kg−1) | 9450 a | 7660 b |
Total N (mg kg−1) | 529 a | 458 b |
Total P (µg g−1) | 165 a | 145 b |
Available P (µg g−1) | 3.2 a | 3.5 a |
Exchangeable Ca (cmol kg−1 suelo) | 0.21 a | 0.18 b |
Exchangeable Mg (cmol kg−1 suelo) | 0.16 a | 0.07 b |
Exchangeable K (cmol kg−1 suelo) | 0.10 a | 0.04 b |
Exchangeable Na (cmol kg−1 suelo) | 0.10 a | 0.05 b |
Total exchangeable bases (cmol kg−1 suelo) | 0.57 a | 0.34 b |
Exchangeable Aluminium (cmol kg−1 suelo) | 0.62 a | 0.72 b |
Microbial C (µg g−1) | 153 a | 113 b |
Microbial N (µg g−1) | 17.3 a | 10.2 b |
Microbial P (µg g−1) | 8.9 a | 9.0 a |
Acid phosphatase activity (µg PNP g−1∙h−1) | 2.4 a | 2.2 a |
4. Conclusions
Habitat | Locality | Depth(cm) | Density(n/m2) | Biomass(g/m2) | Reference |
---|---|---|---|---|---|
Grassland | Laguna Verde, México | - | 1000 | 49.2 | Lavelle et al. [56] |
Humid grassland | Yurimaguas, Perú | 30 | 573 | 116.4 | Lavelle and Pashanasi [57] |
Dry grassland | Yurimaguas, Perú | 30 | 474 | 78 | Lavelle and Pashanasi [57] |
Grassland | Río Branco, Brasil | - | 20 | 13.4 | Guerra [49] |
Grassland | Carimagua, Colombia | 60 | 96.9 | 62.1 | Jiménez et al. [49] |
Tropical savanna | Costa de Marfil, África | 60 | 91-400 | 13-54 | Lavelle [58] |
Tropical savanna | México | - | 236 | 44.1 | Fragoso [59] |
Tropical savanna | Carimagua, Colombia | 60 | 57.8 | 5.00 | Jiménez et al. [4] |
Tropical savanna | Puerto Ayacucho, Venezuela | 30 | 35.2 | 1.09 | Araujo and López-Hernández [5,6] |
Agroforestal system | Puerto Ayacucho, Venezuela | 30 | 155.2 | 18.6 | Araujo and López-Hernández [5,6] |
Tropical savanna | Guarico, Venezuela | 30 | 22.40 | 5.17 | Hernández [60] |
Protected savanna | Guarico, Venezuela | 30 | 64.0 | 32.9 | Hernández [60] |
Acknowledgements
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López-Hernández, D. Earthworm Populations in Savannas of the Orinoco Basin. A Review of Studies in Long-Term Agricultural-Managed and Protected Ecosystems. Agriculture 2012, 2, 87-108. https://doi.org/10.3390/agriculture2020087
López-Hernández D. Earthworm Populations in Savannas of the Orinoco Basin. A Review of Studies in Long-Term Agricultural-Managed and Protected Ecosystems. Agriculture. 2012; 2(2):87-108. https://doi.org/10.3390/agriculture2020087
Chicago/Turabian StyleLópez-Hernández, Danilo. 2012. "Earthworm Populations in Savannas of the Orinoco Basin. A Review of Studies in Long-Term Agricultural-Managed and Protected Ecosystems" Agriculture 2, no. 2: 87-108. https://doi.org/10.3390/agriculture2020087