Academic literature on the topic 'Resprouting'

Resprouting is an important trait that allows plants to persist after fire and is considered a key functional trait in woody plants. While resprouting is well documented in fire-prone biomes, information is scarce in non-fire-prone ecosystems, such as New Zealand (NZ) forests. Our objective was to investigate patterns of post-fire resprouting in NZ by identifying the ability of species to resprout and quantifying the resprouting rates within the local plant community. Fire occurrence is likely to increase in NZ as a consequence of climate change, and this investigation addresses an important knowledge gap needed for planning restoration actions in fire-susceptible regions. The study was conducted in two phases: (1) A detailed review of the resprouting ability of the NZ woody flora, and (2) a field study where the post-fire responses of plants were quantified. The field study was undertaken in the eastern South Island, where woody plants (>5 cm diameter at 30 cm height) were sampled in 10 plots (10x10 m), five- and 10-months post-fire. The research synthesized the resprouting ability of 73 woody species and is the first to provide extensive quantitative data on resprouting in NZ. Most of the canopy dominant species were non-resprouters, but many smaller trees and shrubs were capable of resprouting, despite their evolution in an environment with low fire frequency. Species composition and abundance were important predictors of resprouting patterns among plots, with similar communities resulting in similar resprouting responses. Resprouting capacity provides species with a competitive advantage in the post-fire recovery. We suggest that it is possible to engineer more fire resilient restoration plantings by planting higher proportions of the resprouters identified in this study. The incorporation of resprouting as a trait in restoration plans is likely to be relevant not just in NZ, but also in other non-fire-prone regions facing increases in fire frequency.

Resprouting is an important functional trait for determining community dynamics and the persistence of individuals and populations. However, community-wide research on resprouting has primarily focused on severely damaged trees. We investigated resprouting from trees in a range of undisturbed natural forests along an elevational gradient in central Japan and analyzed the data at inter- and intraspecific levels. First, we formulated interspecific relationships among resprout production, parent stem growth, multi-stemmedness, and dominance in forest communities using a structural equation model (SEM). Second, we analyzed intraspecific variation in the resprout number per stem for nine resprouting species using a hierarchical Bayesian method. We found that resprout production and parent stem growth were negatively correlated; resprouting resulted in multi-stemmed adult forms, and species with multi-stemmed forms tended to be less dominant in undisturbed forest communities. We observed various intraspecific resprouting responses to parental and environmental factors. For example, soil temperature had generally positive effects for most species, whereas dbh appeared to have only weak effects on a few species. Our SEM summarized well the direct and indirect relationships of species’ traits, including resprout production, in the undisturbed forests. The observed intraspecific patterns in the resprouting responses can serve as a starting point for understanding species’ traits within this context.

It has been hypothesised that high-intensity fires prevent fire-dependent fynbos from being replaced by fire-avoiding subtropical thicket on dune landscapes of the Cape Floristic Region (CFR). Recent extensive fires provided an opportunity to test this hypothesis. We posit that (1) fire-related thicket shrub mortality would be size dependent, with smaller individuals suffering higher mortality than larger ones; and (2) that survival and resprouting vigour of thicket shrubs would be negatively correlated with fire severity. We assessed survival and resprouting vigour post-fire in relation to fire severity and pre-fire shrub size at two dune landscapes in the CFR. Fire severity was scored at the base of the shrub and categorised into four levels. Pre-fire size was quantified as an index of lignotuber diameter and stem count of each shrub. Resprouting vigour consisted of two variables; resprouting shoot count and resprouting canopy volume. A total of 29 species were surveyed. Post-fire survival of thicket was high (83–85%). We found that smaller shrubs did have a lower probability of post-fire survival than larger individuals but could detect no consistent relationship between shrub mortality and fire severity. Fire severity had a positive effect on resprouting shoot count but a variable effect on resprouting volume. Pre-fire size was positively related to survival and both measures of resprouting vigour. We conclude that thicket is resilient to high-severity fires but may be vulnerable to frequent fires. Prescribed high-intensity fires in dune landscapes are unlikely to reduce the extent of thicket and promote fynbos expansion.

Resprouting is one of the main regeneration strategies in woody plants that allows post-fire vegetation recovery. However, the stress produced by fires promotes the biosynthesis of compounds which could affect the post-fire resprouting, and this approach has been poorly evaluated in fire ecology. In this study, we evaluate the changes in the concentration of chlorophylls, carotenoids, phenolic compounds, and tannins as a result of experimental burns (EB). We asked whether this biochemical response to fire could influence the resprouting responses. For that, we conducted three EB in three successive years in three different experimental units. Specifically, we selected six woody species from the Chaco region, and we analyzed their biochemical responses to EB. We used spectrophotometric methods to quantify the metabolites, and morphological variables to estimate the resprouting responses. Applying a multivariate analysis, we built an index to estimate the biochemical response to fire to EB per each species. Our results demonstrate that photosynthetic pigment concentration did not vary significantly in burnt plants that resprout in response to EB, whereas concentrations of secondary metabolites (phenolic compounds and tannins) increased up to two years after EB. Our main results showed that phenolic compounds could play a significant role in the resprouting responses, while photosynthetic pigments seem to have a minor but significant role. Such results were reaffirmed by the significant correlation between the biochemical response to fire and both resprouting capacity and resprouting growth. However, we observed that the biochemical response effect on resprouting was lower in tree species than in shrubby species. Our study contributes to the understanding of the biochemical responses that are involved in the post-fire vegetation recovery.

Gymnosperms are generally regarded as poor resprouters, especially when compared to angiosperms and particularly following major disturbance. However, is it this clear-cut? This review investigates two main aspects of gymnosperm resprouting: (i) various papers have provided exceptions to the above generalization—how frequent are these exceptions and are there any taxonomic trends?; and (ii) assuming gymnosperms are poor resprouters are there any anatomical or physiological reasons why this is the case? Five of six non-coniferous gymnosperm genera and 24 of 80 conifer genera had at least one species with a well-developed resprouting capability. This was a wider range than would be expected from the usual observation ‘gymnosperms are poor resprouters’. All conifer families had at least three resprouting genera, except the monospecific Sciadopityaceae. Apart from the aboveground stem, buds were also recorded arising from more specialised structures (e.g., lignotubers, tubers, burls and underground stems). In some larger genera it appeared that only a relatively small proportion of species were resprouters and often only when young. The poor resprouting performance of mature plants may stem from a high proportion of apparently ‘blank’ leaf axils. Axillary meristems have been recorded in a wide range of conifer species, but they often did not form an apical dome, leaf primordia or vascular connections. Buds or meristems that did form often abscised at an early stage. While this review has confirmed that conifers do not resprout to the same degree as angiosperms, it was found that a wide diversity of gymnosperm genera can recover vegetatively after substantial disturbance. Further structural studies are needed, especially of: (i) apparently blank leaf axils and the initial development of axillary meristems; (ii) specialised regeneration structures; and (iii) why high variability can occur in the resprouting capacity within species of a single genus and within genera of the same family.

AbstractWoody plant resprouting has received considerable attention in the last two decades as human disturbances continue to encroach on terrestrial ecosystems globally. We examined the regeneration mechanisms of a Caatinga dry forest in the context of slash-and-burn agriculture and resprouting ability of the local flora. We excavated two old fields (from 32) experiencing early forest regeneration dominated by the tree Pityrocarpa moniliformis (Fabaceae) to map clonal propagation and, in parallel, submitted 260 seedlings from 13 woody plant species to experimental clipping. What seemed to be ‘seedlings’ popping up around P. moniliformis stumps and remaining adults actually were condensed sets of root suckers connected via complex networks of long, ramified shallow horizontal roots without taproots. We mapped respectively 39 and 783 connected root suckers, which summed 96 m and 910 m in root length. Regarding the seedlings, 33% resprouted across nine species with resprouting rates varying between 5–100%. Seedling height before clipping positively influenced resprouting vigour. Our preliminary results suggest that the Caatinga dry forest supports a relatively high proportion of resprouting species, some of them able to clonally propagate and playing an ecosystem-level role by responding to early forest regeneration and high abundance/biomass across both regenerating and old-growth forests.

The potential of vegetation recovery through resprouting of plant tissue from buds after the removal of aboveground biomass is a key resilience strategy for populations under abrupt environmental change. Resprouting leads to fast regeneration, particularly after the implementation of mechanical mowing as part of active management for promoting open habitats. We investigated whether recovery dynamics of resprouting and the threat of habitat conversion can be predicted by optical and structural stand traits derived from drone imagery in a protected heathland area. We conducted multivariate regression for variable selection and random forest regression for predictive modeling using 50 spectral predictors, textural features and height parameters to quantify Calluna resprouting and grass invasion in before-mowing images that were related to vegetation recovery in after-mowing imagery. The study reveals that Calluna resprouting can be explained by significant optical predictors of mainly green reflectance in parental individuals. In contrast, grass encroachment is identified by structural canopy properties that indicate before-mowing grass interpenetration as starting points for after-mowing dispersal. We prove the concept of trait propagation through time providing significant derivates for a low-cost drone system. It can be utilized to build drone-based decision support systems for evaluating consequences and requirements of habitat management practice.

Plant regeneration strategies are commonly dichotomised as ‘resprouter’ v. ‘non-resprouter’, but this fails to recognise that the extent and type of resprouting following fire disturbance vary within species. Here, we report a case of widespread mortality of resprouters following a fire that burnt 98% of an 80-km2 island in Bass Strait, Australia. A field survey, which assessed woody vegetation in 197 plots across the island, showed fire severity ranged from low to high, with crown defoliation occurring across 85% of the island. In total, 1826 of the 1831 woody stems in the burnt plots were top-killed. Only 7.5% resprouted, despite 89% of the stems belonging to species that have the capacity to resprout. Even in species with at least 5% resprouting, only 22% of top-killed stems resprouted. Resprouting rates were maximal (30%) at intermediate fire severity, and only 5 and 8% at the lowest and highest severity classes respectively. Our findings demonstrate the need to understand factors influencing resprouting, and to incorporate these when modelling vegetation recovery after wildfire.

Includes bibliographical references (p. 100-107)
This study investigated the carbon allocation patterns that enable the spindle form of Acacia karroa found in the HluhluweiMfolozi Park, KwaZulu-Natal, to survive repeated and frequent topkill. The central hypotheses were that resprouting is dependent on root carbohydrate reserves and that very frequent topkill would progressively lower the carbohydrate reserves of a plant and eventually cause mortality.

The aim of this study was to gain a comprehensive understanding of the patterns of carbon partitioning, storage and remobilization in Acacia karroo during the juvenile life history stage. Tuber total nonstructural carbohydrate (TNC) concentrations and δ¹³C values were determined in plants from two different stages in the juvenile life history of A. karroo. These were one year after a fire when the plant consisted of numerous leafy shoots or coppices (coppicing stage) and three years after a fire when the plant consisted of one pole like stem (gulliver stage). Gullivers were found to have mean TNC pools of 150g and mean TNC concentrations of 33%. Coppices had mean TNC pools of97g and TNC concentrations of 24%. Both total TNC pools and TNC concentrations in gullivers were significantly higher (p < 0.05) than in coppices. Carbon isotopes were used to determine whether growth was based on carbon reserves as heterotrophic growth shows a distinct enrichment in δ¹³C. The water relations of plants can also influence the δ¹³C values of plant growth. However, there were no significant differences in root size and depth between the stages, indicating that all plants had access to similar water sources. Mean δ¹³C values from the stems of plants in the gulliver stage were significantly enriched(> 1‰) in ¹³C compared to both coppicing plants (p < 0.01) and adults (p < 0.05). The negative δ¹³C values in coppice stems suggest that their growth is not based on stored carbon. The enriched δ¹³C values found in the gulliver stems support the hypothesis that carbon reserves are utilized to achieve fast growth rates in an attempt to escape the fire trap. However, the small magnitude of the differences in δ¹³C between the two stages suggests post-burn regrowth is derived from both current photosynthate and stored carbon.

Thesis (MScConEcol)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The fire-prone mediterranean-type climate regions of the world are immensely biodiverse. Changes in fire frequency due to anthropogenic ignitions and climate change are one of the factors threatening the plant diversity of these regions. Many postfire regeneration studies have focused on seedling recruitment, whereas much can still be learned about regeneration through resprouting. This project focused on resprouters after a fire and assessed if there are differences between the obligate (OS) and facultative (FS) resprouting life history types. OS species have to resprout after fire, as their seeds are not fire resistant and seedling recruitment takes place in fire-free periods, whereas FS species have the ability to resprout and recruit seedlings after a fire. My analyses found a significant difference in postfire resprout success between OS species and FS species, supporting the division of woody resprouting shrubs into these two life history types. OS species had minimal fire-related mortality and this was related to their ability to resprout early and vigorously after fire. OS species had no postfire mortality, which points to traits that enable them to endure the hot and dry summer months. The FS species varied in their response to fire and had greater fire induced mortality than the OS species. Postfire mortality (post-sprouting) was also greater compared to OS species, especially towards the end of the long dry summer suggesting a link to water stress. A postfire seedling survey of target FS, OS and non-sprouters (NS), revealed that NS species had seedling/adult ratios that were orders of magnitude higher ranging between 40-200 seedlings per adult against less than 1-10 seedlings per adults for FS, with OS species recruiting no seedlings directly postfire, as is consistent with their life history type. Although the NS species do not sprout and the FS species had some mortality, the population was at or above replacement two-year postfire on account of seedling recruitment. OS species maintained their pre-fire population by successfully resprouting and by experiencing almost no postfire mortality. These results provide strong justification for grouping woody resprouters into OS and FS species in future studies seeking to understand the underlying differences in postfire recovery. Postfire flowering phenology was also observed during the two year study period. Geophytes, mostly belonging to the Iridaceae and Orchidaceae were overrepresented within the first year postfire, many displaying fire-stimulated flowering. This suggests that some geophytes limit their reproductive cycle to the immediate postfire environment, when nutrients and light are abundant. Smaller resprouting shrubs generally flowered earlier than larger resprouting shrubs. Many non-sprouting shrubs did not reach maturity within the study period and those that did mostly belonged to the Fabaceae and Asteraceae families. This study added 71 species to the existing Paarl Mountain species list, including eight new red listed species, highlighting the importance of early postfire field surveys.
AFRIKAANSE OPSOMMING: Veldbrande is ‘n natuurlike verskynsel in die meditereense klimaatstreke van die wereld. Hierdie areas is ook bekend vir hulle ryk biodiversiteit. Veranderinge in die vuur frekwensie as gevolg van klimaatsverandering en veldbrande wat deur mense veroorsaak word, bedreig die plantdiversiteit van hierdie streke. Vorige veldbrandstudies het meestal gefokus op saailinge en daar bestaan ‘n groot leemte om regenerasie deur herspruiting beter te verstaan. Hierdie navorsingsprojek fokus op herspruiting van fynbos plante as ‘n oorlewingstrategie na ‘n veldbrand. Spesifiek word daar gekyk na verskille tussen verpligte (VH) en nie-verpligte (fakultatiewe) herspruiters (FH). VH spesies moet herspruit na vuur om hulle populasie stabiel te hou, aangesien hulle saad nie vuurbestand is nie. FH spesies het die vermoë om te herspruit sowel as saailinge te werf na ‘n brand. Die studie bevindinge dui op betekenisvolle verskille tussen hierdie twee lewensgeskiedenistipes en regverdig die groepering van houtagtige herspruiter spesies as VH of FH. VH het minimale mortaliteit getoon na die veldbrand. Bykans alle plante het vinnig en kragtig herspruit. VH besit ook eienskappe wat hulle in staat stel om die warm, droeë somers te oorleef. Die oorlewing van FH was wisselvallig, met mortaliteit as gevolg van direkte vuurskade en verdere mortaliteit gedurende die lang somermaande, moonlik as gevolg van water stress. ‘n Saailingstudie van VH, FH en ook nie-spruiters (NS) het getoon dat die saailing/volwasse verhoudings van NS ordes hoër is as die van FH. VH het geen saailinge direk na die vuur geproduseer nie. Twee jaar na die vuur was FH en NS saailing getalle steeds heelwat meer as die aantal volwasse plante wat dood is in die veldbrand. VH het hul populasie stabiliteit gehandhaaf deurdat alle volwasse plante suksesvol herspruit het. Hierdie bevindinge regverdig die verdeling van herspruitende fynbos spesies as VH of FH. Verdere studies is belangrik om die onderliggende ekofisiologiese verskille tussen die twee lewensgeskiedenistipes beter te verstaan. Die blompatrone van verskillende spesies is ook aangeteken tydens die tweejaar studieperiode. Bolplante, veral in die iris- (Iridaceae) en orgidee (Orchidaceae) families het oorheers gedurende die eerste jaar na die brand, aanduidend van ‘n vuur-gestimuleerde blompatroon. Sommige bolplante mag hul voorplantingssiklus beperk tot die periode direk na veldbrand, terwyl daar genoeg lig is en die grond verryk is met voedingsstowwe. Kleiner herspruitende struike het in die algemeen vroeër geblom as groter struike. Nieherspruitende struike het meestal nie seksuele volwassenheid bereik binne twee jaar na die veldbrand nie, buiten sommige in die ertjie- (Fabaceae) en asterfamilies (Asteraceae). Die studie het 71 nuwe spesies tot die bestaande Paarlberg spesielys gevoeg, waarvan agt rooidataspesies was, wat die waarde van plantopnames direk na ‘n veldbrand beklemtoon.

The frequency and intensity of forest disturbances are projected to increase in many regions as climate changes, with an increased likelihood of multiple disturbance events occurring in short succession. The effects and importance of multiple disturbance events are gaining increasing attention but there is substantial uncertainty regarding the strength of interactions in relation to type, sequence, and relative timing. Forests play an integral role in climate change mitigation efforts, however, multiple disturbances could alter forest carbon dynamics, potentially reducing the storage capacity of impacted stands. Accurate accounting of carbon losses and transformations is thus imperative across forests globally, and particularly in non-conifer dominated types and with different responses such as resprouting. This study investigated the effects of a global change-type drought (2010-11) and the Waroona Fire (2016), singularly on forest carbon dynamics in the regrowth Northern Jarrah (Eucalyptus marginata) Forest of southwestern Australia. This was followed by an investigation of the additive and interactive effects of these two disturbances on forest structure and recruitment. The affected forest stands were assessed using a plot-based forest inventory method combined with allometric equations and remote sensing metrics to determine carbon transformations and fire severity. Following the drought die-off there was a significant loss of live standing carbon (49.3 t C ha-1), and a corresponding significant increase in the dead standing carbon pool six months after the drought. The Waroona Fire caused pyrogenic carbon emissions of between 10 and 21 t C ha-1, which corresponded to 5.5-12.2% of the mean pre-fire carbon storage, and the conversion of 59.2 – 72.8 t C ha-1 from the live to dead standing tree pool. This carbon, which comprises another 30-37% of the pre-fire carbon storage will be susceptible to loss over time both from decomposition and from future fires. Total immediate carbon emissions from the 360 km2 wildfire were estimated at 723,113 t C. When the disturbances were examined in combination there was no evidence of linked or compounding effects of these disturbances. Instead a strong effect of wildfire on live basal area (-20.7 ± 7.3 m2 ha-1) overwhelmed pre-existing drought impacts. Eucalypt resprouting forests are particularly resilient, with focal species able to survive multiple stressors over a short time period. However, the newly regrowing burnt stands are vulnerable to future disturbance until they develop bark thick enough to withstand fire, and carbon stores to maintain resprouts following drought. The drought event preferentially removed large trees and the wildfire smaller trees from the live standing carbon pool. With a continually decreasing rainfall and projections of more frequent and severe fires in this area the trajectory of the regrowth in these stands is likely to be strongly tied to the future disturbance regime. Increases in disturbance frequency and intensity may therefore lessen the chances of these forests recovering to pre-fire structure and therefore carbon storage capacity.

Balanites maughamii is an ecologically and culturally valuable tree species, heavily impacted by elephants, which strip bark selectively off the largest trees, increasing their susceptibility to fire damage. Elephants also break intermediate sized trees extensively, keeping them trapped in non-reproductive stages. The trees can however survive breaking, stripping and · toppling by elephants, as well as top kill by fires, because they resprout vigorously in response to damage. They also produce root suckers. independently of disturbance. Vegetative reproduction buffers the populations from the infrequent recruitment of seedlings, and facilitates the maintenance of populations over the short term. Balanites maughamii trees are reliant on African elephants (Loxodonta africana) for seed dispersal and to provide a germination cue through mastication. In the absence of elephants, the population experiences a recruitment bottleneck, but root suckers functionally replace seedlings and fill the "recruitment gap", so over the short term, the population is resilient. In all populations, whether elephants are present or not, another hurdle affects recruitment, and it is seed limitation due to seed predation pre- and post- dispersal. Cafeteria experiments revealed that bushveld gerbils (Tatera leucogaster) were removing many seeds but do not scatter- or larder-hoard. They are simply seed predators.

Orientador: Thomas Michael Lewinsohn
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Perturbações naturais ou antrópicas podem induzir mudanças fenotípicas nas plantas, que por sua vez podem influenciar herbívoros, predadores e polinizadores. Fatores abióticos, tais como nutrientes também podem influenciar a recuperação das plantas. Neste estudo investigamos o efeito de poda experimental em artrópodos associados a plantas rebrotadas em populações naturais de Chromolaena pungens (Asteraceae: Eupatoriae), uma planta subarbustiva, perene e nativa de cerrado. Os objetivos deste trabalho foram avaliar como o rebrote após corte raso ou poda parcial e o suprimento de nutrientes influenciam: (i) o crescimento vegetativo, (ii) a reprodução e os caracteres florais, (iii) a abundância de galhas, insetos folívoros, insetos sugadores e seus predadores; (iv) a comunidade de insetos endófagos associados e a incidência de seus parasitóides. O experimento seguiu um desenho de dois fatores em blocos, onde foram manipulados corte (controle, corte parcial e corte raso) e nutrientes (sem adição de nutrientes e com adição de nutrientes). Plantas cortadas na base foram menores, produziram menos folhas e capítulos, tiveram sua fenologia retardada em um mês em comparação com plantas controle ou de corte parcial. No entanto, a taxa de crescimento, a área foliar e o tamanho dos capítulos foram maiores em plantas submetidas a corte raso. Tais plantas sofreram maiores níveis de herbivoria foliar e destruição de sementes. Além disso, a abundância, a riqueza, a diversidade de espécies de endófagos associados a capítulos de plantas cortadas foram maiores do que em plantas controle ou parcialmente cortadas. Em conseqüência, a composição de espécies endófagas diferiu entre plantas submetidas a diferentes tipos de corte. Por isso, os resultados deste estudo são relevantes para o entendimento de interações inseto-planta em ambientes que sofrem perturbações naturais ou antrópicas recorrentes
Abstract: Natural or human-induced disturbances may promote plant phenotypic modifications, developmental and phenological changes which, in turn, may influence herbivores, predators and pollinators. Abiotic factors, especially nutrient availability, may also influence plant recovery. In this study, we evaluated plant regrowth and arthropod responses to experimental clipping plants in natural populations of Chromolaena pungens (Asteraceae: Eupatoriae), a perennial, native shrub in the Brazilian Cerrado. In particular, we assess how resprouting after severe or partial damage and nutrients influence: (i) vegetative regrowth; (ii) reproductive effort and floral traits; (iii) the abundance of galling, leaf-chewing and sap-sucking insects and their predaceous arthropods; (iv) endophagous insects and their parasitoids. The experiment followed a two-factor randomized block design, respectivelly clipping (control, partial clipping and basal clipping) and nutrients (no nutrient added and with nutrients added). Basally clipped plants were smaller, produced fewer leaves and flowerheads than partially clipped and control plants, moreover heir floral phenology was delayed by one month. However, the relative elongation rate, leaf area and flowerhead size were greater in basally clipped plants. These plants also suffered higher leaf herbivory and seed destruction. Moreover, the abundance, species richness and abundance of flowerhead endophages were higher in basally clipped plants than in the other treatments. Not surprisingly, species composition differed among clipping treatments. For this reason, these findings contribute to the knowledge of insect-plant interactions in recurringly disturbed habitats
Mestrado
Ecologia
Mestre em Ecologia

As espécies do gênero Smilax L., conhecidas popularmente como salsaparrilha, são empregadas na medicina popular desde o século XVI, porém essas plantas ainda são exploradas de maneira extrativista. Com o aumento da comercialização de plantas medicinais cresce a necessidade de trabalhos que certifiquem a qualidade da matéria prima. A caracterização anatômica e o perfil químico certamente fornecem uma base mais segura nessa certificação. Visando auxiliar no atendimento da demanda e apontar propostas do manejo sustentável em áreas de ocorrência natural de Smilax fluminensis Steud. os objetivos do presente estudo foram: a) analisar a morfoanatomia dos órgãos vegetativos e indicar as características de valor diagnóstico para essa espécie; b) analisar o perfil químico de S. fluminensis através da Cromatografia Líquida de Alta Eficiência acoplada com Detector de Arranjo de Diodos utilizando-se extratos metanólicos (EMeOH) de raízes, rizóforos e ramos aéreos; c) realizar estudos de germinação de sementes e de propagação vegetativa por estacas de ramos aéreos e subterrâneos e, d) acompanhar ao longo de um ano a capacidade de rebrotamento das plantas no campo. As análises ao microscópio de luz foram realizadas utilizando-se as técnicas usuais para o preparo de lâminas semipermamentes e permanentes. Para as análises no microscópio eletrônico de varredura, amostras de folhas foram fixadas em Karnovsky, desidratadas em série etílica e submetidas ao método do ponto crítico de CO2, montadas sobre suportes de alumínio e metalizadas. As sementes foram submetidas a diferentes temperaturas, sob fotoperíodo diário de oito horas e na ausência de luz. Para o enraizamento de estacas, foram utilizados ramos aéreos e subterrâneos com aproximadamente 20 cm, com duas regiões nodais submetidas ao tratamento com ácido indolbutírico a 100 ppm ou apenas em água destilada. Dentre os caracteres anatômicos que permitiram a delimitação da espécie destacam-se: estômatos anisocíticos e paracíticos presentes na epiderme da face abaxial; cera epicuticular na forma de grânulos globosos; mesofilo homogêneo com ampla câmara subestomática; presença da bainha amilífera nos primeiros entrenós do caule aéreo; presença de endoderme com reforço em U; ausência de meristema de espessamento no rizóforo adulto; presença de exoderme com estrias de Caspary nas raízes brancas e ausência de córtex interno nas raízes marrons. Em relação ao perfil químico, os extratos obtidos apresentaram picos correspondentes às substâncias: ácido clorogênico, ácido cafeico, rutina, ácido p-cumárico, ácido ferúlico e ácido trans-cinâmico. As melhores porcentagens de germinação foram 80% em 20-30º C no claro e 85% a 30ºC no escuro. Apenas as estacas de ramos subterrâneos enraizaram. Ao final de um ano de acompanhamento das plantas no campo, todas apresentaram em média 4.05 novos brotamentos. As espécies cujas partes utilizadas para o preparo dos medicamentos são as raízes correm maior risco de extinção como é o caso de S. fluminensis. Portanto, a capacidade de propagação por sementes, por estacas e de regeneração de ramos aéreos após a remoção de parte das estruturas subterrâneas aliada ao perfil químico confirma o seu potencial para a exploração econômica de maneira sustentável, sendo uma alternativa para reduzir o extrativismo predatório dessa espécie nativa.
The Smilax L. species, popularly known as salsaparrilha, have been used in folk medicine since the sixteenth century; however, these plants have still been handled in extractive way. With the increasing commercialization of medicinal plants, there is need to study to certify the raw material quality. Anatomical analyses and chemical profile characterization certainly provides a more secure basis to this certification. Aiming to meet the demand and to point proposals for sustainable management of natural occurrence of Smilax fluminensis Steud., the objectives of this study were: a) to analyze the morph-anatomy of vegetative organs and indicate the features of diagnostic value for this species, b) to examine the chemical profile of S. fluminensis by High Performance Liquid Chromatography Coupled with Diode Array Detector using methanol extracts (EMeOH) of roots, rhizophore and stems c) to conduct studies of seed germination and vegetative propagation on cuttings of aerial and subterranean stems and d) to monitor, over a year, the resprouting ability of plants in the field. We carried out the analyses under a light microscopy using the usual techniques for preparing semi-permanent and permanent slides. To perform the analyses under a scanning electron microscopy, leaf samples were fixed in Karnovsky, dehydrated in ethanol series and subjected to critical point method of CO2, mounted on aluminum supports and coated with gold. Seeds were exposed to different temperatures under a daily photoperiod of eight hours and in the absence of light. To analyze the sprouting, aerial and subterranean stems were used with about 20 cm of length, with two nodal regions subjected to treatment with IBA at 100 ppm or in distilled water. Among the anatomical features that enable delimitation of the species are: anisocytic and paracytic stomata in the epidermis of the abaxial surface, epicuticular wax in the form of granules globules, homogeneous mesophyll with large substomatal chambers, presence of starch sheath in the first internodes of the aerial stem, the presence of endoderm-reinforced U and the absence of primary thickening meristem in the adult rhizophore, exodermis with Casparian strips in roots, and the absence of inner cortex in brown roots. Regarding the chemical profile, extracts showed peaks corresponding to the following substances: chlorogenic acid, caffeic acid, rutin, p-coumaric acid, ferulic acid and trans-Cinnamic acid. The best germination was 80% at 20-30ºC under light and 85% at 30ºC in the dark. Only roots sprouted. After one year of monitoring the plants in the field, all had an average of 4.05 new aerial shoots. The species whose roots are used for the preparation of medicines face a greater risk of extinction as is the case of S. fluminensis. Therefore, the ability to spread by seeds, cuttings and shoots regeneration after removal of aerial stems combined with the chemical profile confirms its potential for economic use in a sustainable manner, and an alternative to reduce the predatory extraction of native species.

Les pertorbacions com el foc i la sequera són naturals a la conca mediterrània, però per la situació actual d'escalfament global i absència de gestió forestal, els episodis de sequera cada cop són més freqüents i severs. Aquests episodis de sequera, acompanyats de l'abandonament de les zones rurals de l'últim mig segle, han afavorit el desenvolupament d'una gran quantitat i continuïtat de vegetació (combustible des del punt de vista dels incendis) més seca i morta (disponible). Aquesta major quantitat de combustible i més sec generen uns incendis de major intensitat. A part d'aquests aspectes relacionats amb el canvi global, la mateixa fisiologia de les espècies forestals, pot afavorir les pèrdues d'aigua a través de la transpiració nocturna o cuticular, per exemple, malgrat que la seva regulació encara resulta ser una gran desconeguda avui en dia. S'ha indicat com aquests dos processos poden augmentar encara més la falta d'aigua, sobretot en condicions d'estrès, el que augmentaria el risc d'incendis i podria dificultar la recuperació de la vegetació després de la pertorbació. En aquest sentit, s'ha apuntat que les adaptacions fisiològiques per resistir la sequera poden arribar a ser antagòniques amb les adaptacions per resistir els incendis. Aquesta tesi doctoral busca unir els processos fisiològics responsables per la resistència a la sequera amb la resposta de les plantes als incendis i, en particular, el rebrot. Amb aquesta finalitat s'han combinat una sèrie d'estudis bibliogràfics i meta-analítics amb estudis de camp. Hem constatat com adaptacions a la sequera, com ara la resistència a l'embolisme poden estar negativament relacionades amb la resistència als incendis de baixa intensitat. Però, la recuperació del rebrot després d'incendis d'alta intensitat que eliminen la biomassa arbòria depenen de què el grau d'embolisme hagi estat limitant. Hem documentat com la variació en la conductància cuticular pot, efectivament, augmentar de forma considerable l'estrès hídric sobretot en espècies perennes i, finalment, hem realitzat una síntesi global sobre els factors que expliquen les pèrdues d'aigua nocturnes.
Perturbaciones como el fuego y la sequía son naturales en la cuenca mediterránea, pero el calentamiento global y la ausencia de gestión forestal favorecen que los episodios de sequía sean cada vez más frecuentes y severos. Estos episodios de sequía, acompañados del abandono de las zonas rurales durante el último siglo, han favorecido el desarrollo de una gran cantidad y continuidad de vegetación (combustible desde el punto de vista de los incendios) que está cada vez más y, por tanto, más disponible para las llamas. Esta mayor cantidad de combustible seco aumenta la probabilidad de que sufrir grandes incendios. Aparte de estos aspectos relacionados con el cambio global, la propia fisiología de las especies forestales puede favorecer las pérdidas de agua a través de la transpiración nocturna o cuticular, por ejemplo, aunque su regulación resulta todavía una gran desconocida a día de hoy. Se ha indicado como estos dos procesos pueden aumentar todavía más la falta de agua, sobretodo en condiciones de estrés, lo que aumentaría el riesgo de incendios y podría dificultar la recuperación de la vegetación tras la perturbación. En este sentido, se ha apuntado que las adaptaciones fisiológicas para resistir a la sequía pueden llegar a ser antagónicas con las adaptaciones para resistir a los incendios Esta tesis doctoral busca unir los procesos fisiológicos responsables por la resistencia a la sequía con la respuesta de las plantas a los incendios y, en particular, el rebrote. A tal fin se han combinado una serie de estudios bibliográficos y meta-analíticos con estudios de campo. Hemos constatado como adaptaciones a la sequía, tales como resistencia al embolismo pueden estar negativamente relacionadas con la resistencia a los incendios de baja intensidad. Sin embargo, la recuperación del rebrote tras incendios de alta intensidad que eliminan la biomasa arbórea depende del grado de embolismo antes del incendio. Hemos documentado también como la variación en la conductancia cuticular puede, efectivamente, aumentar de forma considerable el estrés hídrico sobretodo en especies perennes y, finalmente, hemos realizado una síntesis global sobre los factores que explican la apertura estomática nocturna.
Disturbances such as fire and drought are natural in the Mediterranean basin, but global warming and lack of forest management interact to enhance drought episodes that are becoming more frequent and severe. These drought episodes, accompanied by the abandonment of rural areas over the last century, have favoured the development of a large vegetation (fuel) loads that are increasingly drier and, consequently, more available to the fire. This increasing amount of dry fuel is consequently enhancing the probability of suffering a large fire. In addition to global change factors, some physiological traits may favour water losses through nocturnal or cuticular transpiration, for instance, although their regulation is still largely unknown at present. It has been pointed out how these two processes can further increase water scarcity, especially under stressful conditions, which would increase the risk of fire and could hinder the recovery of vegetation after disturbance. In this sense, it has been suggested that physiological adaptations to resist drought may become antagonistic to adaptations to resist fire. This PhD thesis seeks to link the physiological processes responsible for drought resistance with the response of plants to fire and, in particular, resprouting. To this end, a series of bibliographical and meta-analytical studies have been combined with field studies. I found that adaptations to drought, such as resistance to embolism, can be negatively related to resistance to low intensity fire. However, resprouting recovery after high-intensity fires that remove aboveground biomass depends on the degree of hydrcaulic conductance before the perturbation. I have documented how variation in cuticular conductance can indeed considerably increase water stress, especially in perennial species and, finally, I have performed a global synthesis on the factors that explain nocturnal stomatal conductance.