In the high Andes of Ecuador scarcity of farmland has led to accelerated deforestation, in particular over the last 40 years. Soil mis‐management has caused the rapid decline of soil fertility and most farmland has been irreversibly transformed into grassland or tree plantations. The present study assessed whether pastures and particularly pine plantations were associated with less soil nutrients. The soils from six sites each of native forests and Pinus patula plantations, and their adjacent pastures were sampled in a geographically large area in the Paute watershed, south Ecuador. Soil analyses showed statistically significant differences for soil cations and effective cation exchange capacity (ECEC) only. ECEC was highest in soils from native forests and their adjacent pastures (6.4 cmol/kg) compared to pine plantations and their pastures (4.2 cmol/kg). Mean soil organic matter and pH were similar in native forests/pastures (39% SOM; pH 5.4) and in plantations/pastures (40% SOM; pH 5). As pasture soils had ECEC concentrations statistically similar to those of their adjacent forest or plantation, they do not form a single homogeneous land use type based on soil nutrients. Therefore, this study cannot conclude that the presence of pines alone has caused soil degradation, but instead that the soil at the site was already degraded before pines were planted. This study proposes the scenario that pine plantations are established in pastures as a last resort, when the soils are already strongly degraded, and more profitable land uses are not available. Farmers are reluctant to use fertile land for tree plantations, and only the planting of well‐known species, such as pines, is officially encouraged.
SummaryThe potential impact of genetically modified (GM) crops on biodiversity is one of the main concerns in an environmental risk assessment (ERA). The likelihood of outcrossing and pollenmediated gene flow from GM crops and non-GM crops are explained by the same principles and depend primarily on the biology of the species. We conducted a national-scale study of the likelihood of outcrossing between 11 GM crops and vascular plants in Chile by use of a systematized database that included cultivated, introduced and native plant species in Chile. The database included geographical distributions and key biological and agronomical characteristics for 3505 introduced, 4993 native and 257 cultivated (of which 11 were native and 246 were introduced) plant species. Out of the considered GM crops (cotton, soya bean, maize, grape, wheat, rice, sugar beet, alfalfa, canola, tomato and potato), only potato and tomato presented native relatives (66 species total). Introduced relative species showed that three GM groups were formed having: a) up to one introduced relative (cotton and soya bean), b) up to two (rice, grape, maize and wheat) and c) from two to seven (sugar beet, alfalfa, canola, tomato and potato). In particular, GM crops presenting introduced noncultivated relative species were canola (1 relative species), alfalfa (up to 4), rice (1), tomato (up to 2) and potato (up to 2). The outcrossing potential between species [OP; scaled from 'very low' (1) to 'very high' (5)] was developed, showing medium OPs (3) for GM-native relative interactions when they occurred, low (2) for GMs and introduced noncultivated and high (4) for the grape-Vitis vinifera GM-introduced cultivated interaction. This analytical tool might be useful for future ERA for unconfined GM crop release in Chile.
In the Andes, little is known about the relationships among current land uses and their effect on soil fertility. Corn (Zea mays L.) was used to evaluate soil quality for plant growth on soils of four land uses, along an expected gradient of fertility: native forests (Nf) > pastures (Pa) > Eucalyptus globulus Labill. plantations (Eg) > Pinus patula Schlecht. plantations (Pp). Corn was grown in soils taken from four different areas, for the four land uses in each. In a common garden, a randomized block design was used with four treatments: controls (C), ammonium nitrate (N), triple superphosphate (P), and combined N and P fertilizers (N + P). On soils from Nf, Pa and Eg, fertilization response was N + P > P > N > C; corn biomass (g/pot −1 ) averaged 4.5 in N + P, 3.3 in P, 1.8 in N, 1.7 in C; P content (mg/pot −1 ) averaged 12 in N + P, 11.9 in P, 2.3 in N, 2 in C. N + P enhanced growth the most. Mortality was high on Pp soils, growth weak, and fertilization response was P > N + P > C ≥ N; corn biomass (g/pot −1 ) was 0.9 in P, 0.5 in N + P, 0.8 in C, 0.4 in N; P content (mg/pot −1 ) was 4.4 in P, 2.3 in N + P, 1.8 in C, 1 in N. All soils had P, K, Ca and Mg deficiencies. Al toxicity possibly occurred only in Pp soils. All control soils had low fertility. Responses to N and P were high except for Pp. Pastures and plantations were once natural forests converted to agriculture, then to pastures as soil fertility declined. Plantations were likely established on poorest pastures; only pine grew on poorest soils. This land use endpoint has the lowest agricultural potential; other land uses * Corresponding author. G. Chacón et al. 1130have limitations in P, N, and potentially K.
A national‐scale study of outcrossing potential within Chilean vascular flora was conducted using an upgraded algorithm, which adds parameters such as pollinator agents, climate, and geographic conditions. Datasets were organized and linked in a Web platform (www.flujogenico.cl), in which the development of a total outcrossing potential (TOP) predictor was formulated. The TOP predictor is the engine in the Web platform, which models the effect of a type of agricultural practice on others (coexistence calculation mode) and on the environment (biodiversity calculation mode). The scale for TOP results uses quintiles in order to define outcrossing potential between species as “very low,” “low,” “medium,” “high,” or “very high.” In a coexistence analysis considering 256 species (207 genera), the 10 highest TOP values were for genera Citrus, Prunus, Trifolium, Brassica, Allium, Eucalyptus, Cucurbita, Solanum, Lollium, and Lotus. The highest TOP for species in this analysis fell at “high” potential, 4.9% of the determined values. In biodiversity mode, seven out of 256 cultivated species (2.7%) were native, and 249 (97.3%) corresponded to introduced species. The highest TOP was obtained in the genera Senecio, Calceolaria, Viola, Solanum, Poa, Alstroemeria, Valeriana, Vicia, Atriplex, and Campanula, showing “high” potential in 4.9% of the values. On the other hand, 137 genetically modified species, including the commercial and pre‐commercial developments, were included and represented 100 genera. Among these, 22 genera had relatives (i.e., members of the same genus) in the native/introduced group. The genera with the highest number of native/introduced relatives ranged from one (Ipomea, Limonium, Carica, Potentilla, Lotus, Castanea, and Daucus) to 66 species (Solanum). The highest TOP was obtained when the same species were coincident in both groups, such as for Carica chilensis, Prosopis tamarugo, and Solanum tuberosum. Results are discussed from the perspective of assessing the possible impact of cultivated species on Chilean flora biodiversity. The TOP predictor (http://epc.agroinformatica.cl/) is useful in the context of environmental risk assessment.
Manuscrito recibido el 29 de agosto de 2016. Aceptado, tras revisión, el 11 de octubre de 2016. ResumenEn los altos Andes del Ecuador, aunque la agricultura extensiva y el sobrepastoreo tienen impactos negativos en el suelo, aún se desconoce qué práctica reduce más su fertilidad. El crecimiento de quínoa (Chenopodium quinoa Willd.) fue evaluado en suelos de bosques nativos (Bn), pastizales (Pa), plantaciones de Eucalyptus globulus Labill. (Eg) y Pinus patula Schlecht. (Pp). Se aplicó un bioensayo con un diseño de bloques al azar con controles, C; nitrato de amonio, N; superfosfato triple, P; y N+P combinados. En suelos de Pp la mortalidad de quínoa fue del 100 % en N, 88 % en C, 63 % en N+P y 0 % en P. El P fue el que más incrementó el crecimiento. La biomasa de quínoa alcanzó solo 0,1 g/pote, con un contenido de P de 0,7 mg/pote. En los demás suelos, el N+P fue el que más incrementó el crecimiento. La biomasa de quínoa (g/pote) promedió 0,1 en C; 0,4 en N; 1,6 en P y 7,2 en N+P; el contenido de P (mg/pote) promedió 0,9 en C; 0,6 en N; 12 en P y 38 en N+P. En todos los suelos, el PO − 4 fue el elemento primordial deficitario; el K lo fue seguramente en Pp, con toxicidad de Al. Este estudio sugiere que estos suelos no pueden soportar la producción de quínoa sin fertilización combinada esencialmente con P y K. Los suelos de Pp son los que más deficiencias presentaron probablemente debido a una historia de uso más prolongada después del pastoreo y al propio efecto del pino.Palabras claves: potencial agrícola, deficiencias de nutrientes, suelos volcánicos. 16LA GRANJA:Revista de Ciencias de la Vida 24(2) 2016:16-28. c 2016, Universidad Politécnica Salesiana, Ecuador. Quinoa biomass production capacity and soil nutrient deficiencies in pastures, tree plantations and native forests in the Andean Highlands of Southern Ecuador AbstractIn the high Andes of Ecuador, although expanding agricultural practices and overgrazing have had negative impacts on soil fertility, few investigations have been conducted to identify which practices are most likely to reduce fertility. Quinoa (Chenopodium quinoa Willd.) was grown in soils from native forests, Nf; pastures, Pa; Eucalyptus globulus Labill. plantations, Eg; and Pinus patula Schlecht. plantations, Pp. A bioassay study was conducted using a randomized block design with control (C), ammonium nitrate (N), triple superphosphate (P), and combined N and P (N+P) fertilizer treatments. On soils from Pp, quinoa mortality was 100 % in N, 88 % in C, 63 % in N+P and 0 % in P; P enhanced growth the most; quinoa biomass attained only 0.1 g/pot and had a P content of 0.7 mg/pot. N+P enhanced quinoa growth the most on soils from Nf, Pa and Eg. Here, quinoa biomass (g/pot) averaged 0.1 in C, 0.4 in N, 1.6 in P and 7.2 in N+P; P content (mg/pot) averaged 0.9 in C, 0.6 in N, 12 in P and 38 in N+P. In all soils, PO − 4 was the principal limiting factor. K deficiencies and Al toxicity probably occurred only in Pp soils. This study suggests that the studied soils cannot support production of quino...
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