Fenologia remota e os padrões de trocas foliares ao longo de um gradiente de sazonalidade
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Data
2018-08-03
Autores
Alberton, Bruna de Costa [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O estudo da fenologia vegetal busca monitorar, compreender e prever os ciclos de vida recorrentes das plantas, principalmente influenciados pelo clima. O monitoramento das fenofases vegetativas de brotamento e senescência foliar são essências para a compreensão de processos ecossistêmicos importantes como, a produtividade primária, as trocas de energia entre atmosfera e superfície terrestre, o fluxo de carbono, e a ciclagem de nutrientes. Logo, entender a resposta das plantas ao clima e ser capaz de prever alterações em sua fenologia, é essencial para o entendimento das dinâmicas de comunidades vegetais e da funcionalidade dos ecossistemas em frente a cenários de mudanças climáticas. Nos últimos anos, a busca por novas tecnologias dentro de estudos científicos vem crescendo com o intuito de tornar mais viável e amplo o monitoramento fenológico. Neste trabalho, buscamos incorporar novas tecnologias de observações fenológicas com o uso de câmeras digitais (fenocâmeras) instaladas em campo para o monitoramento de dados fenológicos de brotamento e senescência foliar em ambientes tropicais. Os objetivos gerais deste trabalho de tese, dividida em quatro seções, foram de : (i) compilar informações sobre conceitos e propriedades da técnica de fotografias repetidas (repeated photograph technic), criando um protocolo para o uso de câmeras digitais nos trópicos e levantar suas principais contribuições no âmbito na biologia da conservação; (ii) monitorar e descrever os padrões da fenologia vegetativa em diferentes comunidades vegetais sazonais, através dos dados obtidos de imagens digitais e investigar os principais gatilhos ambientais atuando nas diferentes vegetações; (iii) associar dados de fenologia foliar juntamente com dados de produtividade primária bruta dentro de ecossistemas sob diferentes pressões de sazonalidade para um melhor entendimento das respostas entre vegetação-atmosfera mediadas pela fenologia foliar; e (iv) apresentar resultados das principais iniciativas em análises de imagens digitais para o monitoramento da fenologia foliar desenvolvidas dentro da rede de fenocâmeras do projeto e-phenology, no âmbito da colaboração e-science. As vegetações estudadas neste trabalho estão distribuídas ao longo de um gradiente de sazonalidade de distribuição de chuvas e incluem: uma vegetação de caatinga; três diferentes fisionomias de cerrado que correspondem a um cerrado campo sujo, um cerrado sensu stricto, e um cerrado denso; e uma vegetação de Mata Atlântica. Séries temporais relacionadas às fenofases vegetativas foram extraídas do conjunto de imagens digitais coletadas em cada uma das áreas e analisadas dentro do contexto de cada um dos objetivos deste trabalho. Demonstramos que o estabelecimento de uma rede de fenocâmeras é uma poderosa ferramenta para a biologia da conservação, através da capacidade de obtermos dados de alta frequência temporal associados a uma ampla gama de dados ambientais monitorados. Através da aplicação de fenocâmeras pode-se obter novas informações sobre prática de manejo e restauração de ambientes, além de sua potencial contribuição nas esferas de educação ambiental e ciência cidadã. Observamos que a disponibilidade de água e luz no ambiente são os fatores mais importantes para o desenvolvimento foliar ao longo de diferentes comunidades sazonais. Relações hídricas em plantas foram mais importantes para vegetações mais áridas, como a caatinga, enquanto que a disponibilidade de luz, quantificada através da sazonalidade do comprimento do dia, teve maior influência no gatilho do desenvolvimento foliar nas comunidades de cerrado. No âmbito dos ecossistemas, demonstrou-se uma nova abordagem ao se relacionar a fenologia foliar derivada de câmeras com a produtividade de ecossistemas tropicais. A dinâmica fenológica analisada através da variabilidade de sinais fenológicos encontrados dentro das diferentes vegetações, foram importantes para explicar os padrões temporais de produtividade dos ecossistemas. A compilação de trabalhos realizados através da colaboração e-science, apresentados na seção 4, foram de grande importância para o desenvolvimento dos métodos e análises, bem como para o alcance dos resultados obtidos dentro desta tese. Este trabalho oferece uma nova ferramenta para o monitoramento fenológico em vegetações tropicais, e sugere novos desafios a serem desenvolvidos bem como incentiva uma maior abrangência no uso de fenocâmeras a fim de cobrir um maior número de áreas e diferentes tipos de vegetação, além de associar estes estudos com abordagens desenvolvidas em diferentes escalas como as observações diretas, a aplicação de imagens de drones, bem como com as imagens de satélite. A comparação de diferentes escalas espaciais e temporais irá nos ajudar a entender melhor a própria escala de informações provenientes das fenocâmeras em termos de abrangência e detalhamento dos ecossistemas.
Plant phenology is a traditional science focused on monitoring, understanding, and predicting recurrent life cycles events, which are mainly related to climate Leaf development stages are essential plant phenophases for the better understanding of ecosystems processes such as carbon and water fluxes, regulation of productivity, and nutrient cycling. Through the investigation of plant responses to climate and phenological shifts prediction, we can better forecast climatic change effects on vegetation dynamics and prevent loss of ecosystems functionalities. Aiming to become the phenological collection wider and more feasible worldwide, the seek for new technologies has stimulated several research centers of plant phenology monitoring. Here, we incorporated a new technology of field phenological observations using digital cameras for the monitoring of leaf exchanges in tropical vegetations. On this work, divided into four sections, we aimed to: (i) compile information about concepts and properties of the repeated photograph technic, create guidelines for the phenocams setup in tropical vegetation sites, and to provide key contributions of daily imagery monitoring on biological conservation; (ii) to stablish a monitoring of different seasonal vegetations, describing the phenological trends, and identify the environmental cues which are triggering the leaf flushing and senescence for each vegetation type; (iii) analyze the canopy greenness obtained from digital cameras in relation to gross primary productivity measurements, to better understand the role of leaf phenology controlling ecosystem productivity in the tropics; and (iv) present some results of phenocam image analysis research initiatives and tools devised in the context of e-Science collaborations and built in the framework of the e-phenology project and the e-phenology network of phenocams. The selected study sites belong to different seasonal biomes, which comprehends areas from caatinga, savanna grasslands, savanna woodlands and Atlantic rainforest. Temporal series representing foliar phenology were extracted from the data imagery of each vegetation site and were analyzed into the context of each section of this work. We demonstrated that the establishment of phenocam networking is a powerful tool for biological conservation through its capability of fine temporal resolution data associated with wide spatial monitoring coverage. Besides, phenocams applications can bring new information for management and restoration practices at several sites and environments and contribute for the education for conservation and citizen science initiatives. We observed that water and light were the most important predictors for the leaf phenological patterns across seasonal vegetation communities. Water-plant relationships were more important for the caatinga community, and light, through day-length seasonality, had more influence in the leafing patterns of the cerrado communities. Regarding the ecosystem, we demonstrated a novel approach to relate leaf phenology to seasonality of tropical ecosystems productivity. The phenological dynamics regarding the variability of species phenological signals, and how they are built in into each contrasting vegetation communities explains drivers of leaf phenology and productivity. A compilation of articles developed through the e-science collaboration, presented in Section 4, were of great importance for the generation of methods and analytical work, as well as for the results achievements in this thesis. This work will offer a new tool for the phenological monitoring in the tropics, and suggests next challenges to be addressed and the continuity of the e-phenology network and the spread of new cameras covering new vegetation types; the development of bottom-up studies, integrating on-the-ground observations, cameras, drones, and satellites, inter-comparing them and placing camera-derived phenology in its own scale, by understanding how much and what kind of information can be retrieved from ecosystems.
Plant phenology is a traditional science focused on monitoring, understanding, and predicting recurrent life cycles events, which are mainly related to climate Leaf development stages are essential plant phenophases for the better understanding of ecosystems processes such as carbon and water fluxes, regulation of productivity, and nutrient cycling. Through the investigation of plant responses to climate and phenological shifts prediction, we can better forecast climatic change effects on vegetation dynamics and prevent loss of ecosystems functionalities. Aiming to become the phenological collection wider and more feasible worldwide, the seek for new technologies has stimulated several research centers of plant phenology monitoring. Here, we incorporated a new technology of field phenological observations using digital cameras for the monitoring of leaf exchanges in tropical vegetations. On this work, divided into four sections, we aimed to: (i) compile information about concepts and properties of the repeated photograph technic, create guidelines for the phenocams setup in tropical vegetation sites, and to provide key contributions of daily imagery monitoring on biological conservation; (ii) to stablish a monitoring of different seasonal vegetations, describing the phenological trends, and identify the environmental cues which are triggering the leaf flushing and senescence for each vegetation type; (iii) analyze the canopy greenness obtained from digital cameras in relation to gross primary productivity measurements, to better understand the role of leaf phenology controlling ecosystem productivity in the tropics; and (iv) present some results of phenocam image analysis research initiatives and tools devised in the context of e-Science collaborations and built in the framework of the e-phenology project and the e-phenology network of phenocams. The selected study sites belong to different seasonal biomes, which comprehends areas from caatinga, savanna grasslands, savanna woodlands and Atlantic rainforest. Temporal series representing foliar phenology were extracted from the data imagery of each vegetation site and were analyzed into the context of each section of this work. We demonstrated that the establishment of phenocam networking is a powerful tool for biological conservation through its capability of fine temporal resolution data associated with wide spatial monitoring coverage. Besides, phenocams applications can bring new information for management and restoration practices at several sites and environments and contribute for the education for conservation and citizen science initiatives. We observed that water and light were the most important predictors for the leaf phenological patterns across seasonal vegetation communities. Water-plant relationships were more important for the caatinga community, and light, through day-length seasonality, had more influence in the leafing patterns of the cerrado communities. Regarding the ecosystem, we demonstrated a novel approach to relate leaf phenology to seasonality of tropical ecosystems productivity. The phenological dynamics regarding the variability of species phenological signals, and how they are built in into each contrasting vegetation communities explains drivers of leaf phenology and productivity. A compilation of articles developed through the e-science collaboration, presented in Section 4, were of great importance for the generation of methods and analytical work, as well as for the results achievements in this thesis. This work will offer a new tool for the phenological monitoring in the tropics, and suggests next challenges to be addressed and the continuity of the e-phenology network and the spread of new cameras covering new vegetation types; the development of bottom-up studies, integrating on-the-ground observations, cameras, drones, and satellites, inter-comparing them and placing camera-derived phenology in its own scale, by understanding how much and what kind of information can be retrieved from ecosystems.
Descrição
Palavras-chave
Fenocâmeras, Sazonalidade, Fenologia vegetativa, Produtividade do ecossistema, Imagens digitais, Phenocameras, Seasonality, Vegetative phenology, Ecosystem productivity, Digital images