Contribución al estudio fitosociológico del pinar grancanario (Islas Canarias)

Salas, M., Del Arco, M.J. & Pérez de Paz, P.L. Contribución al estudio fitosociológico del pinar grancanario (Islas Canarias). Lazaroa 19:99-117 (1998). Se lleva a cabo una caracterización bioclimática, florística y fitosociológica de Pinetum canariensis, el pinar autóctono de la isla de Gran Canaria, y se describe la nueva subasociación juniperetosum canariensis. Se hacen diversas consideraciones sobre las comunidades arbustivas de sustitución y se describe la nueva asociación Euphorbio regis-jubae-Cistetum monspeliensis

Efecto de la inclinación y pedregosidad sobre el reparto del agua de lluvia, su cuantificación y aplicación al estudio de la vegetación en zonas áridas

Para conocer la correcta distribución de la vegeta - ción en un territorio, es fundamental manejar información precisa sobre las variables que la condicionan. Muy probable - mente, el parámetro que condiciona en mayor medida el tipo de vegetación que puede crecer en un lugar es la cantidad de agua de que disponen las plantas. En este sentido, y dejando a un lado las formaciones ligadas a cursos de agua, lagos, etc., el principal origen de este recurso es la lluvia. De esta manera, el estudio de la distribución de la vegetación en cualquier territorio está muy relacionado con el análisis de las precipitaciones que recibe. Para conocer la cantidad de agua de lluvia que recibe una zona se recurre siempre a los datos aportados por las estaciones meteorológicas situadas en la misma. Los datos recogidos por estas estaciones se aplican a una superficie hipotética, homogénea y plana. Esta infor - mación es suficientemente precisa cuando la escala a la que se trabaja es pequeña (1:100.000; 1:50.000), pero cuando se precisa de un mayor detalle, sobre todo en territorios áridos, donde la estructura de la vegetación es abierta y el suelo recibe directamente gran parte de la precipitación, existen condiciones del terreno que condicionan el reparto del agua de lluvia y por tanto el acceso de las plantas a este recurso. Dos de estas variables, quizá las más importantes son la inclinación y la presencia de afloramientos rocosos o de pedregosidad en el suelo. En definitiva, nuestro trabajo consiste en proponer diferentes modelos matemáticos que posibiliten conocer la cantidad real de agua de que disponen las plantas, que denominamos A . Este valor se obtiene a partir de los datos pluviométricos ( P ), relacionándolos con la inclinación del terreno y el porcentaje del mismo ocupado por rocas ( af ). La relación entre la precipitación y la inclinación nos proporciona un valor que denominamos precipitación real ( P ́ ), que es menor cuanto mayor es la inclinación, ya que la cantidad de agua caída debe repartirse en una superficie mayor. La cantidad de afloramiento rocoso aumenta la escorrentía, acumulando agua en las zonas terrosas situadas entre las rocas, por lo que un mayor porcentaje de pedre - gosidad en el suelo conlleva una acumulación de agua en el suelo que lo rodea. De esta manera se proporciona un modelo que permite tanto explicar mejor la distribución de la vegetación en zonas áridas y a escalas grandes (1:25.000 o mayores). Para contrastar el modelo y comprobar su utilidad, se ha realizado un estudio del mismo en diferentes localidades situadas en territorios áridos de la isla de Gran Canaria, una de las Islas Canarias. En esta isla se escogieron 14 lo - calidades situadas en ambientes áridos, con precipitaciones siempre inferiores a 200 mm/m 2 . Entre estas localidades, de condiciones climáticas similares, existe una diversidad vegetal muy importante. La mayor parte están ocupadas por un matorral crasicaule muy abierto dominado por Euphorbia balsamifera , denominado tabaibal de tabaiba dulce, propio de las zonas más desérticas del Archipiélago Canario, y considerado la vegetación potencial de sus zonas áridas e hiperáridas..

Effect of slope and stoniness on the distribution of rainwater, its quantification and application to the study of vegetation in arid zones

For the correct distribution of vegetation in an area, it is essential to manage accurate information on the variables that condition information. Most likely, the parameter that determines further the type of vegetation that can grow in one place is the amount of water available to plants. In this sense, and leaving aside the formations linked to watercourses, lakes, etc., the main source of this resource is the rain. Thus, the study of the distribution of vegetation in any territory is closely related to the analysis of rainfall it receives. To know the amount of rainwater that receives a zone always uses data provided by meteorological stations located in the same. The data collected by these stations are applied to a hypothetical, uniform and flat surface. This information is accurate enough when the scale at which it works is small (1: 100,000, 1: 50,000), but when it requires greater detail, especially in arid areas where the vegetation structure is open and the soil directly receives much of the rainfall, soil conditions exist that determine the distribution of rainwater and therefore access to this resource plants. Two of these variables, perhaps the most important are the inclination and the presence of rocky outcrops or stoniness on the floor. In short, our job is to propose different mathematical models that allow to know the actual amount of water available to plants, we call A. This value is obtained from rainfall data (P), relating to the sloping terrain and the percentage of it occupied by rocks (af). The relationship  between precipitation and tilt gives us a value we call the real precipitation (P'), which is lower the greater the inclination, since the amount of rainfall should be distributed over a larger area. The amount of rocky outcrop increases runoff, accumulating water in the earthy areas between the rocks, so a higher percentage of stoniness in soil involves an accumulation of water in the surrounding soil. Thus a model that allows both better explain the distribution of vegetation in arid areas and on large scales (: 25.000 or higher 1) is provided. To test the model and test its usefulness, it has made a study of it in different localities in arid areas of the island of Gran Canaria, one of the Canary Islands. On this island 14 towns located in arid environments, with precipitation always less than 200 mm/m2 were chosen. Among these locations, with similar climatic conditions, there is a very important plant diversity. Most are occupied by a crasicaule very open scrub dominated by Euphorbia balsamífera, called tabaibal de tabaiba dulce, typical of the most barren areas of the Canary Islands, and considered the potential of its arid and hyper-arid vegetation areas. But other situations are occupied by a lush vegetation: the cardonal, almost totally enclosed high scrub, dominated by Euphorbia canariensis, the cardón; and even formations characterized by the presence of a undertree thicket where different woody species such as Olea cerasiformis, wild olive, Juniperus turbinata subsp. canariensis, the sabina, and even the Canary Island pine, Pinus canariensis. These same plant formations appear as potential in areas with higher rainfall, so its presence in these arid areas should be related to some variable affecting the distribution of water resources. For each of these locations was made calculating the amount of water available to plants, obtaining results that meet the alleged contradiction to find different types of vegetation, with different water requirements in the same climatic zone. Thus it is improving the proposed model provides when it comes to study how vegetation is distributed in arid and territories detail scale is checked. It is clear that as we decrease the scale of the study of the distribution of vegetation in any territory, it is essential to increase the parameters analyzed, especially if it comes to analyzing the situation of vegetation in arid, where the structure of vegetation and seasonality of rainfall make the characteristics of the substrate affect significantly to the presence of vegetation way. Given the scarcity of water resources in these ecosystems, any aspect influencing the availability of water for plants will be of great importance for understanding distribution

Contribución al conocimiento de la flora y vegetación de El Hierro (Islas Canarias) I

In this paper a study is made of 165 taxa collected at 27 different localities on the island of Fi Hierro (Canary Islands). 12 of these are new to the island and are preceded by a dot (•) in the final list of taxa. The localities are arranged according to the different vegetation iones. Comments on the species collected and on potential and actual vegetation are included.Se estudian 165 taxones recolectados en 27 localidades de la Isla de El Hierro. De ellos, 12 constituyen la primera cita para la isla, y se incluyen en la lista final de taxones precedidos por un punto (•). Se han ordenado las localidades de acuerdo con los diferentes pisos de vegetación. Se incluyen comentarios acerca de las especies recolectadas, así como sobre la vegetación potencial y actual de las localidades estudiadas

Efectos de un incendio forestal (Tenerife, Islas Canarias, verano de 2007) bajo bosques de pinar sobre algunas propiedades del suelo y su relación con la repelencia al agua a corto y medio plazo

Forest fires modify the soil environment, often triggering severe soil degradation. In this paper, we studied the impact of a large northern Tenerife Canary pine forest wildfire on a set of relevant soil properties, focusing on their evolution in time and relationship with soil water repellency. To do this, soils were sampled at four sites (burned and non-burned) and several soil physical and chemical parameters were measured. The results show significant variations for soil pH, electric conductivity (CE1:5), and NH4+-N between burned and non-burned samples, whereas non-significant increases were found in burned soils for oxidizable carbon (Cox), total nitrogen (Ntot), Ca2+, Mg2+, Na+ and K+, and soil hydrophobicity. The differences caused by the fire were no longer evident one year later. Furthermore, in one sampling site (Vitric Leptosols under low pine forest with a mixed heath/beech tree understory) a wide variation in the content of Cox and Ntot and high water repellency was observed relative to the other sites. These differences can be attributed to the composition of the understory vegetation. Significant correlations between soil hydrophobicity with CE1:5, aggregate stability and the contents of Cox, Ntot, NH4+-N, Ca2+, Mg2+, Na+ and K+ were found.Os incêndios florestais provocam alterações nas propriedades do solo, que por vezes conduzem a uma severa degradação. Neste artigo avalia-se o impacto em algunas propriedades do solo depois de um incêndio numa floresta de pinheiros, ao N de Tenerife (Ilhas Canárias), bem como a sua evolução temporal e relação com a hidrofobicidade do solo. Recolheram-se amostras de solo em quatro locais (áreas queimadas e não queimadas) na zona afectada pelo incêndio, tendo-se efectuado a determinação de alguns importantes parâmetros físicos e químicos. Os resultados obtidos mostram variações significativas entre os locais amostrados queimados e não queimados no que se refere aos valores de pH, condutividade elétrica (CE1:5), e teor em NH4+-N,contrariamente ao que se veificou em relação aos teores de carbono oxidável (Cox), azoto total (Ntot) , Ca2+, Mg2+, Na+ e K+ extraíveis, e hidrofobicidade do solo. As diferenças causadas pelo fogo, tendem a desaparecer um ano depois. Além disso, no ponto D (Leptosol vitrico com pinheiro canário e matorral de faial-brezal) observou-se uma grande variação no teor de C oxidável, N total e repelência à água, em comparação com os outros locais estudados, atribuindo-se as diferenças à composição do matorral. Finalmente, observaram-se correlações significativas entre a hidrofobicidade do solo e a CE1:5, a estabilidade dos agregados e os conteúdos de Cox, Ntot, NH4+-N, Ca2+, Mg2+, Na+ e K+ extraíveisLos incendios forestales alteran las propiedades de los suelos, llegando en ocasiones a desencadenar severos procesos de degradación. En este trabajo se evalúa el impacto sobre algunas propiedades fisicoquímicas en suelos afectados por un incendio bajo bosque de pinar canario en el norte de Tenerife, así como su evolución temporal y la posible relación con la repelencia al agua del suelo. Para ello, se han muestreado cuatro ubicaciones (quemadas y no quemadas) en las que se han medido parámetros físicos y químicos relevantes del suelo. Los resultados muestran variaciones significativas en los valores de pH, conductividad eléctrica (C.E.1:5), y NH4+-N. También se han detectado aumentos, en este caso no significativos, en los suelos quemados en el contenido de carbono oxidable (Cox), nitrógeno total (Ntot), Ca2+, Mg2+, Na+ y K+ asimilables, y en la hidrofobicidad. Las diferencias inducidas por el incendio tienden a desaparecer un año después. Además, en una de las ubicaciones (Leptosol vítrico bajo pinar canario con sotobosque de fayal brezal) se han observado grandes diferencias en el contenido de Cox y Ntot, así como elevada repelencia al agua en relación a las restantes localidades estudiadas, las cuales se atribuyen a la composición del sotobosque. Se han encontrado correlaciones significativas entre la hidrofobicidad del suelo con la C.E.1:5, la estabilidad de los agregados y los contenidos de Cox, Ntot, NH4+-N, Ca2+, Mg2+, Na+ y K+ asimilables

Short- and long-term effects of fire in subtropical cloud forests on an oceanic island

The recurrence of fires has increased considerably due to human activity, affecting even forests where traditionally fire is uncommon. In this study, we verify the effects of degradation caused by fire in the Canarian laurel forests, which is a subtropical forest formation restricted to the humid montane areas of these Macaronesian islands. We evaluated the effect of fire by comparing a series of burned plots corresponding to fires from 1960, 1984, 1995, to 2012 with geographically proximate and comparable unburned plots in the Garajonay National Park (La Gomera Island, Spain). We focused on three aspects that are immediately altered by fire: forest structure, floristic composition, and microclimate. These aspects have been quantified using (a) tree density, the Pielou index using tree height classes, and DBH for the vertical structure of the forest; (b) DCA, the Bray Curtis dissimilarity index, and a species indicator analysis for the floristic composition; and (c) temperature and relative humidity for microclimate under three canopy cover conditions. Our results reveal that, overall, structural complexity and its composition in the burned areas have barely reached 40% and 35%, respectively, when compared with unburned areas, and recovery mainly depends on time since fire. Additionally, burned plots presented more pioneer species, a higher density of trees, and climatic variables tend to have a wider range throughout the day. These data reveal the long time span that this ecosystem needs for recovery to a prefire state and how it may be more prone to subsequent fire events.We also thank the financial support from the Canary Islands Government through their programme of financial support for researchers co funded in a 85% by the European Social Fund and from the Spanish Ministerio de Agricultura, Alimentación y Pesca and the Organismo Autónomo de Parques Nacionales, which supported the research project titled “Cuantificando la respuesta a los incendios forestales de las comunidades de plantas y artrópodos de los bosques de laurisilva del Parque Nacional de Garajonay>.Peer Reviewe

Biogeographic origins and drivers of alien plant invasions in the Canary Islands

Aim: Understanding the historical and contemporaneous drivers of invasion success in island systems can decisively contribute to identifying sources and pathways that are more likely to give rise to new invaders. Based on a floristic-driven approach, we aimed at determining the origins of the invasive alien flora of the Canary Islands and shedding light in the mechanisms shaping their distribution within the archipelago.This research was supported by the Fundación BBVA project (INVASION - PR19_ECO_0046) and the Spanish Ministry of Science and Innovation (MICINN) project (ASTERALIEN - PID2019-110538GA-I00). J.M.-L. was funded by the INVASION Fundación BBVA project and by a Juan de la Cierva-Formación Fellowship (MICIIN; reference FJC2020-046353-I). Y.A. by the ASTERALIEN MICINN project. J.P. was funded by the MICINN through the Ramón y Cajal Program (RYC-2016-20506). L.S.J.G. was funded by the Academia Canaria de Investigación Gobierno de Canarias FPI 2021 Fellowship (TESIS2021010101). The authors also thank Dr. D. Chapman and two anonymous reviewers for their constructive comments and suggestions. No permits were needed to perform this study.Peer reviewe