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Authors
Abstract(s)
O sobreiro (Quercus suber) é, em Portugal, uma árvore de importante valor económico, social e ambiental, surgindo frequentemente em sistemas mistos com pinheiro manso (Pinus pinea) nas regiões sul de Portugal. Tem-se verificado o declínio acentuado dos sobreiros, sendo o oomiceta Phytophthora cinnamomi, aliado a má gestão e às alterações climáticas, uma das causas apontadas.
Este trabalho teve como objetivo estudar as interações ecológicas entre o sobreiro e o pinheiro manso quando infetados por P. cinnamomi. Questionamos se os sobreiros infetados seriam mais afetados por P. cinnamomi em combinação intraespecífica, em combinação interespecífica ou crescendo isolados. Foi realizado um ensaio experimental em vaso durante 18 meses com dois tratamentos e cinco combinações das duas espécies. Também construímos um modelo para avaliar indiretamente a área foliar de plantas jovens usando fotografias de perfil simples.
Não foram encontrados sintomas ou mortes associadas à infeção das plantas por P. cinnamomi. Porém, as plantas inoculadas apresentaram maior biomassa de raiz total, maior biomassa de raízes finas e maior número de ramificações em comparação às plantas controlo, embora estas diferenças não tenham sido significativas. Provavelmente ocorreu infeção, mas as condições ambientais ótimas de crescimento permitiram que as plantas recuperassem. Além do estudo de inoculação, comprovamos o forte impacto das misturas de espécies na repartição de biomassa entre as partes aérea e radicular. Ambas as espécies preferem crescer isoladas. Porém, o sobreiro tende a competir fortemente com indivíduos da mesma espécie sendo expressivamente dominado pelo pinheiro muito provavelmente devido à competição pela luz. Os sobreiros crescendo com pinheiros mansos apresentaram, no entanto, um rácio raiz/parte aérea significativamente superior, indicando que provavelmente teriam um melhor desempenho no campo em condições de seca.
Requerem-se mais estudos relacionados com a mistura destas espécies, com P. cinnamomi, combinando também stress hídrico. Assim, apresentamos recomendações para melhor implementar e monitorizar futuros trabalhos.
Cork oak (Quercus suber), an important national tree species, frequently appears mixed with stone pine (Pinus pinea) in south Portugal regions. Cork oaks dieback and mortality has been reported since the beginning of last century. Phytophthora cinnamomi, combined with damaging management practices and climate change, are reported as causes for such phenomenon. This work aimed to study the ecological interactions between cork oak and stone pine when infected with P. cinnamomi. We questioned if infected cork oaks would be more affected by P. cinnamomi with the presence of stone pine growing nearby, with siblings or growing isolated. A pot experiment was carried for 18 months with two treatments and five combinations of the two species. We also build a model to assess indirectly the leaf area of small plants using simple profile photographs. No symptoms or deaths associated to P. cinnamomi plant infections were found. However, inoculated plants showed higher total root biomass, greater thin root biomass and greater number of branches than control plants, although these differences were not significant. Plants may have been infected but the optimum environmental growth conditions allowed them to recover. Apart from the inoculation study, we prove the strong impact of species mixture on biomass partitioning between above and belowground parts. Both species prefer to grow isolated. However, cork oak competes severely with siblings and is significantly dominated when growing with stone pine probably due to light competition. Cork oaks growing with stone pines show, nonetheless, a significant higher root/shoot which means they probably would perform better in field under drought stress condition. It is possible to determine accurately the leaf area of plants growing in pots using simple calibrated profile photographs. Further studies are needed relating P. cinnamomi presence combined with drought stress and using these species mixture, so we provide recommendations to improve future works.
Cork oak (Quercus suber), an important national tree species, frequently appears mixed with stone pine (Pinus pinea) in south Portugal regions. Cork oaks dieback and mortality has been reported since the beginning of last century. Phytophthora cinnamomi, combined with damaging management practices and climate change, are reported as causes for such phenomenon. This work aimed to study the ecological interactions between cork oak and stone pine when infected with P. cinnamomi. We questioned if infected cork oaks would be more affected by P. cinnamomi with the presence of stone pine growing nearby, with siblings or growing isolated. A pot experiment was carried for 18 months with two treatments and five combinations of the two species. We also build a model to assess indirectly the leaf area of small plants using simple profile photographs. No symptoms or deaths associated to P. cinnamomi plant infections were found. However, inoculated plants showed higher total root biomass, greater thin root biomass and greater number of branches than control plants, although these differences were not significant. Plants may have been infected but the optimum environmental growth conditions allowed them to recover. Apart from the inoculation study, we prove the strong impact of species mixture on biomass partitioning between above and belowground parts. Both species prefer to grow isolated. However, cork oak competes severely with siblings and is significantly dominated when growing with stone pine probably due to light competition. Cork oaks growing with stone pines show, nonetheless, a significant higher root/shoot which means they probably would perform better in field under drought stress condition. It is possible to determine accurately the leaf area of plants growing in pots using simple calibrated profile photographs. Further studies are needed relating P. cinnamomi presence combined with drought stress and using these species mixture, so we provide recommendations to improve future works.
Description
Mestrado em Engenharia Florestal e dos Recursos Naturais / Instituto Superior de Agronomia, Universidade de Lisboa
Keywords
Quercus suber Pinus pinea declínio agente patogénico interações ecológicas dieback pathogen ecological interactions
Pedagogical Context
Citation
Martins, J.C. Crescimento do sobreiro e pinheiro manso inoculados com Phytophthora cinnamomi: estudo em vaso combinando misturas intraespecíficas e interespecíficas. Lisboa: ISA, 2021, 51 p. Dissertação de Mestrado
Publisher
Instituto Superior de Agronomia, Universidade de Lisboa