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Cultura vs guerra

November 29th, 2015 No comments

No soy muy amante de ir a manifestaciones, aunque apoyo las causas de muchas de ellas. Aquí mis reflexiones de ayer (sábado 28 Noviembre 2015) mientras la gente se manifestaba contra los bombarderos en Siria y otros despropósitos similares.

Comportamientos anacrónicos en la escala internacional: El “ojo por ojo, diente por diente” aun funciona entre países

La cultura, entendida como conjunto de saberes y pautas de conducta de un grupo social que se transmiten por aprendizaje, ha ido incrementando durante toda la historia de la humanidad. Por ejemplo, nuestro sistema de comunicación entre individuos se ha ido perfeccionando desde el origen de los humanos hasta adquirir las sutilezas de nuestro lenguaje actual (evolución cultural). La cultura nos permite gestionar los instintos dentro de un ámbito social. Por ejemplo, muchos animales, incluido primates, serían capaces de tomar cualquier pieza de alimento que se le presente delate, aunque tengan que usar la fuerza. Una persona inmersa en la cultura actual, antes de coger el alimento de un escaparate, primero trabajará para conseguir dinero, después preguntará cuánto vale, y si está de acuerdo con el precio, adquirirá la pieza de comida a cambio del dinero conseguido con esfuerzo. Por lo tanto, la cultura requiere una organización social que hemos ido generando con gran esfuerzo a lo largo de nuestra historia; hemos creado un entramado cultural que permite la convivencia y el desarrollo de la sociedad (contrato social). Una persona que se salte estos procedimientos culturales (p.e., robe la comida del escaparate), la podríamos calificar de tener un comportamiento primitivo o animal, por basarse sólo en los instintos (por ejemplo, el hambre) y no en las convenciones culturales. Los dueños del la tienda podrían denunciar al ladrón, a no ser que estuviésemos en la Edad Media, época en que la respuesta quizá sería dar una paliza al ladrón, aplicando la ley del tailón (“ojo por ojo, diente por diente”). La justicia (la posibilidad de denunciar y realizar juicios independientes con criterios claros preestablecidos) es uno de los procedimientos que nuestra cultura actual proporciona para solucionar conflictos; no en vano se la ha definido como la felicidad social. Otro ejemplo. Si una persona pasa por nuestro jardín sin permiso, hablaríamos con ella para entender por qué lo ha hecho, y en su caso, la denunciaríamos; el juez dictaría sentencia y, si fuera el caso, el intruso pagaría por los perjuicios realizados. Darle una paliza por haber pasado por nuestro jardín sería un acto basado en instintos territoriales ancestrales (en lugar de basarse en la cultura actual); matarlo sería fuera ya de toda razón posible. De manera similar, disparar a un avión porque ‘invade’ durante unos minutos el espacio aéreo de un país o región es solucionar un conflicto de una manera totalmente anacrónica en el mundo actual. Bombardear una región donde viven personas, sean sirios, ladrones, catalanes, yihadistas, médicos-sin-fronteras, falangistas, malabaristas, asesinos, surrealistas, o lo que sea, es mucho más que una simple animalada anacrónica; es utilizar un producto de nuestra cultura (la tecnología) para realizar una “animalada” en masa, es una acción totalmente fuera de nuestra cultura. Sólo se puede entender si la realiza gente sin cultura, sin ética y con una mentalidad maquiavélica extrema. Se supone que la Ilustración nos permitió superar la ley del tailón y los comportamientos basados en la venganza.

pax_dove-of-peaceLecturas relacionadas

Por favor, no repitan la invasión de Irak (V. Navarro)

#NoEnNuestroNombre

Objeción a los gastos militares (renta 2014), jgpausas.blogs.uv.es 1 Mayo 2015

Crisis: gasto social y gasto militar, jgpausas.blogs.uv.es 13 Oct 2011

No a la guerra! – Otra vez!!, jgpausas.blogs.uv.es 20 Mar 2011

 

Lignotubers

November 17th, 2015 1 comment

Lignotubers are swollen woody structures located at the root-shoot transition zone of some plants; they contain numerous dormant buds and starch reserves [1]. They are ontogenetically programmed, that is, they are not the product of repeated disturbances; and thus they can be observed at very early stages of the plant development (other types of basal burls may be a response to multiple disturbances). Lignotubers enables the plant to resprout prolifically after severe disturbances that remove the aboveground biomass, thus they are considered adaptive in fire-prone ecosystems [2]. Lignotubers are not well-known in many floras because they are often below-ground (i.e., detected only after excavation) and because they are often confused by other non-ontogenetically determined basal burls; thus some reports of lignotubers in the literature are mistakes. In a recent review [1] we provide examples of species with a clear evidence of lignotubers in the Mediterranean basin, together with detailed morphological and anatomical description of lignotubers in saplings. The species with lignotuebers in the Mediterranean basin include many Erica species (e.g. E. arborea, E. scoparia, E. australis, E. lusitanica, E. multiflora), the two Arbutus species (A. unedo, A. andrachne), Rhododendron ponticum, Viburnum tinus, Phillyera angustifolia, Quercus suber (not obvious macroscopically!), Tetraclinis articulata and Juniperus oxycedrus (but not in all populations!). Please let me know (email address here) if you know of other Mediterranean basin species with lignotubers! Thanks

lignotubers
Figures: Examples of lignotubers for Mediterranean basin species. A Juniperus oxycedrus (resprouting after fire). B Viburnum tinus. C Arbutus unedo. D Quercus suber (not a clear basal swelling). E Olea europaea. F Phillyrea angustifolia (adult), G Phillyrea angustifolia (saplings). In many species (e.g., V. tinus, A. unedo and P. angustifolia) the lignotuber is only evident after excavating the root-shoot transition zone.

References

[1] Paula S., Naulin P.I., Arce C., Galaz C. & Pausas J.G. 2016. Lignotubers in Mediterranean basin plants. Plant Ecology  [doi | pdf | suppl.]

[2] Keeley J.E., Pausas J.G., Rundel P.W., Bond W.J., Bradstock R.A. 2011. Fire as an evolutionary pressure shaping plant traits. Trends Plant Sci. 16: 406-411.  [doi | sciencedirect | pdf | For managers]

 

Disturbance maintains alternative biome states

November 9th, 2015 No comments

It is becoming more and more evident that climate alone does not explain spatial and temporal patterns of the world vegetation, and that disturbance regimes explain an important part of the variability in vegetation and biome composition and distribution [1]. This has been suggested specially in tropical ecosystems where alternative vegetation states (e.g., forests and savannas) are possible for a given climatic conditions [2]. For instance, in dry years, surface fires may enter in forests and kill fire-sensitive trees and select for fire-resistant woody species with open crown architectures that generates well lit communities with a flammable grassy understory. Forest trees and savannas trees have a marked difference in bark thickness (thinner in the former) and thus a contrasted sensitivity to surface fires [3]. Thus, a switch to a forest state from a savanna depends on a sufficiently long fire interval or high resource availability allowing the outcompetition of shade-intolerant savanna trees and grasses (i.e. the inhibition of fires) by means of a closed canopy of forest trees. Similarly, herbivory can also exert a control on woody biomass and favour herbivory-resistant shrubs and grasses. However, empirical (field-based) evidence for alternative sates were very limited. In a recent paper [4] we used field data to show that, for a wide range of environmental conditions (in South America and Africa), fire feedbacks maintain savannas and forests as alternative biome states in both the Neotropics and the Afrotropics. In addition, wooded grasslands and savannas occurred as alternative states in the Afrotropics, depending on the relative importance of fire and herbivory feedbacks. That is, we found evidence for a disturbance-driven bistability in the Neotropics and a disturbance-driven tristability in Afrotropics (figure below).

Savanna-states

Fig. Top: Frequency distribution of basal area in afrotropical (tristability) and neotropical (bistability) ecosystems. Bottom: The discontinuous pattern of basal area along the resources gradient for both afrotropical and neotropical ecosystems (red: wooded grasslands; orange: savannas; green: forests). Note that there are regions of the gradient where two alternative vegetation types are possible; they are maintained by different disturbance regime (see [4]).

References:
[1] Pausas, J.G. 2015. Alternative fire-driven vegetation states. J. Veget. Sci. 26: 4-6. [doi | pdf | suppl.]

[2] Dantas V., Batalha MA & Pausas JG. 2013. Fire drives functional thresholds on the savanna-forest transition. Ecology 94:2454-2463. [doi | pdf | appendix]

[3] Pausas, J.G. 2015. Bark thickness and fire regime. Funct. Ecol. 29: 317-327. [doi | pdf | suppl.]

[4] Dantas V.L., Hirota M., Oliveira R.S., Pausas J.G. 2016. Disturbance maintains alternative biome states. Ecology Letters 19:12-19 [doi | wiley | pdf |supp.– New!

 

Resprouting at the global scale

November 2nd, 2015 No comments

Plant resprouting (i.e., the ability to form new shoots after destruction of living tissues from disturbance) is often considered a simple qualitative trait and used in many ecological studies. However, resprouting is a trait that increases fitness under many different disturbance types, occurs in a wide range of environments, is widespread in many lineages, and is morphologically very diverse. In a recent paper we review some of the complexities and misunderstandings of resprouting and highlight that cautions is needed when using resprouting ability to predict vegetation responses across disturbance types and biomes [1]. There are marked differences in resprouting depending on the disturbance type, and fire is often the most severe disturbance because it includes both defoliation and lethal temperatures. In the mediterranean biome, there are differences in functional strategies to cope with water deficit between reprouters (dehydration avoiders) and non-resprouters (dehydration tolerators) [1,2]; however, there is little research to unambiguously extrapolate these results to other biomes, and some of the extrapolations seems to be incorrect. In addition, resprouting in the mediterranean biome tends to be binary, that is, species are either resprouters or non-resprouters [3], and intermediate cases are evolutionary unstable [4]; however this is not necessary true in other biomes (e.g., in the tropics). Furthermore, predictions of vegetation responses to changes in disturbance regimes require consideration of not only resprouting but also other relevant traits (e.g., seeding, bark thickness) and the different correlations among traits observed in different biomes [5]; models lacking these details would behave poorly at the global scale. Overall, the lessons learned from a given disturbance regime and biome, like crown-fire mediterranean ecosystems, can guide research in other ecosystems but should not be extrapolated at the global scale.

 

Cistus-Quercus

Fig: Fire allows the coexistence of species with very different strategies: Cistus albidus seedling (left) and Quercus coccifera resprout (right) 10 months after a high intensity fire in eastern Spain (Cortes de Pallás fire, 2012, Valencia). Cistus albidus  is a drought semi-deciduous nonresprouter (obligate postfire seeder ) with a physiological drought-tolerant behavior; Quercus coccifera  is an sclerophyllous (evergreen) obligate resprouter with drought-avoiding traits [2].

References
[1] Pausas, J.G., Pratt, R.B., Keeley, J.E., Jacobsen, A.L., Ramirez, A.R., Vilagrosa, A., Paula, S., Kaneakua-Pia, I.N. & Davis, S.D. 2016. Towards understanding resprouting at the global scale. New Phytologist 209:945-954. [doi | pdf] — New paper!

[2] Vilagrosa A., Hernández E.I., Luis V.C., Cochard H., Pausas, J.G. 2014. Physiological differences explain the co-existence of different regeneration strategies in Mediterranean ecosystems. New Phytologist 201: 1277-1288. [doi | pdf ]

[3] Pausas, J.G., Bradstock, R.A., Keith, D.A., Keeley, J.E. & GCTE Fire Network. 2004. Plant functional traits in relation to fire in crown-fire ecosystems. Ecology 85: 1085-1100. [pdf | esa | doi]

[4] Pausas J.G. & Keeley J.E., 2014. Evolutionary ecology of resprouting and seeding in fire-prone ecosystems. New Phytologist 204: 55-65. [doi | wiley | pdf]

[5] Pausas, J.G. 2015. Bark thickness and fire regime. Functional Ecology 29:317-327. [doi | pdf | suppl.]

 

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