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- Policies for plant diversity conservation on a global scale: a Nitrogen driver analysisPublication . Cruz, Cristina; Dias, Teresa; Pinho, Pedro; Branquinho, Cristina; Máguas, Cristina; Pinto, M. J.; Martins-Loução, Maria AméliaDiversity is a complex term that includes taxonomic, functional, spatial and temporal aspects of organisms variety. Conservation policies must be supported by holistic studies of ecosystem function, must aim to transform scientific knowledge into social responsibility creating a culture of respect towards nature and should also include economic components. Mediterranean ecosystems will likely experience the greatest proportional changes in biodiversity due to the substantial influence of land use and climate change as major drivers. Land use includes not only rural abandonment but also intensive exploitation of native forests (cork oak woodlands) or shrublands for animal or crop production. These last two are dependent on large Nitrogen (N) inputs. In this paper we intend to show the responses of Mediterranean ecosystems to increased N availability in terms of biodiversity and ecosystem functionality. We present two case studies: 1) a gradient of N availability due to a N point source; and 2) N manipulative field experiment (doses and forms). With these results our aim is to pinpoint the importance of improving scientific knowledge at a local level before we establish conservation policies at global level. The two case studies reflect a strong influence of the N source on ecosystem function. Finally, we use the SWOT (Strengths, Weakness, Opportunities and Threats) analysis approach to underpin the complexities of human intervention in the N cycle and the problem it poses for policies of plant conservation.
- Tolerance of young (Ceratonia siliqua L.) carob rootstock to NaClPublication . Correia, P.J.; Gama, F.; Pestana, M.; Martins-Loução, M. A.One-year-old carob (Ceratonia siliqua L.) rootstock was grown in fertilised substrate to evaluate the effects of NaCl salinity stress. The experiment consisted of seven treatments with different concentrations of NaCl in the irrigation water: 0 (control), 15, 30, 40, 80, 120 and 240 (mmol L 1), equivalent to electrical conductivities of 0.0, 1.5, 2.9, 3.9, 7.5, 10.9 and 20.6 dS m 1, respectively. Several growth parameters were measured throughout the experimental period. At the end of the experiment, pH, extractable P and K, and the electrical conductivity of the substrate were assessed in each salinity level. On the same date, the mineral composition of the leaves was compared. The carob rootstock tolerated 13.4 dS m 1 for a period of 30 days but after 60 days the limit of tolerance was only 6.8 dS m 1. Salt tolerance indexes were 12.8 and 4.5 for 30 and 60 days, respectively. This tolerance to salinity resulted from the ability to function with concentrations of Cl and Na+ in leaves up to 24.0 and 8.5 g kg 1, respectively. Biomass allocation to shoots and roots was similar in all treatments, but after 40 days the number of leaves was reduced, particularly at the larger concentrations (120 and 240 mmol NaCl L 1). Leaves of plants irrigated with 240 mmol NaCl L 1 became chlorotic after 30 days exposure. However, concentrations of N, P, Mg and Zn in leaves were not affected significantly (P > 0.05) by salinity. Apparently, K+ and Ca2+ were the key nutrients affected in the response of carob rootstocks to salinity. Plants grown with 80 and 120 mmol L 1 of NaCl contained the greatest K+ concentration. Na+/K+ increased with salinity, due to an elevated Na+ content but K+ uptake was also enhanced, which alleviated some Na+ stress. Ca2+ concentration in leaves was not reduced under salinity. Salinization of irrigation water and subsequent impacts on agricultural soils are now common problems in the Mediterranean region. Under such conditions, carob seems to be a salt as well as a drought tolerant species.
- Unraveling Cryptic Reticulate Relationships and the origin Of Orphan Hybrid Disjunct Populations In NarcissusPublication . Marques, Isabel; Feliner, Gonzalo Nieto; Draper, David; Martins-Loução, Amélia; Aguilar, Javier Fuertes; Society for the Study of EvolutionEvolutionary consequences of natural hybridization between species may vary so drastically depending on spatial, genetic, and ecological factors that multiple approaches are required to uncover them. To unravel the evolutionary history of a controversial hybrid (Narcissus ×perezlarae), here we use four approaches: DNA sequences from five regions (four organellar, one nuclear), cytological studies (chromosome counts and genome size), crossing experiments, and niche modeling. We conclude that (1) it actually consists of two different hybrid taxa, N. ×perezlarae s.s. (N. cavanillesii × N. miniatus) and N. ×alentejanus (N. cavanillesii × N. serotinus); (2) both have been formed several times independently, that is, polytopically; (3) N. cavanillesii was the mother progenitor in most hybridization events. We also address the origin of orphan hybrid populations of N. ×perezlarae in eastern Spain, hundreds of kilometers away from N. cavanillesii. Although long-distance dispersal of already formed hybrids cannot be completely rejected, extirpation of N. cavanillesii via demographic competition is a more likely explanation. Lowreproductive barriers to fertilization by foreign pollen in N. cavanillesii, molecular footprints of the former presence of this species in the area, active asexual propagation by bulbs in N. ×perezlarae, and overlapping ecological niches are consistent with the extirpation scenario.
- O contributo do Jardim Botânico de Lisboa para a Estratégia Global para a Conservação de Plantas (2003-2009)Publication . Martins-Loução, Maria Amélia; Sérgio, Cecilia; Melo, Ireneia; Correia, Ana Isabel; Escudeiro, Alexandra; Barata, Ana Raquel; SimSim, Manuela; Carvalho, Palmira; Pinto, Manuel João; Garcia, César; Figueira, Rui; Brehm, Joana Magos; Draper, David; Marques, Isabel; Rosselò, Antónia; Gomes, Cristina Tauleigne; Cotrim, Helena; Serrano, Helena; Branquinho, Cristina; Clemente, Adelaide