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1.
Growth and physiological response of woody plants to flooding have been analyzed in detail; however, relatively few studies have been oriented towards the effects of water immersion on cambial activity and wood and bark anatomy of trees that are growing in prolonged flooding conditions. These studies are important to understand the possible effects of predicted sea level rising in mangroves as a consequence of global warming. We studied five species growing in a mangrove forest, sampling three to six trees of each species, in sites that have the longest flooding period. Differences in bark appearance and phloem structure between the submerged stem portion and the portion of the stem above the water surface exist in all species. Although aerenchyma formation and stem hypertrophy are the most common events related to flooding, each type of tissue responded differently. Annona glabra L., Laguncularia racemosa (L.) Gaertn f. and Hibiscus tiliaceus L. developed rythidome. Avicennia germinans (L.) Stearn developed rythidome only in the submerged stem portion. Phyllanthus elsiae Urb., developed one periderm in both stem portions. Species that developed rythidome also developed aerenchyma between periderms and in the phellem. H. tiliaceus and P. elsiae, showed the highest values for anatomical phloem and periderm characters below water surface, while an inverse tendency was observed in A. glabra and L. racemosa, suggesting that prolonged flooding modifies vascular cambium and phellogen differently. Results indicate that sea level rising would affect distribution of the species according to their specific flooding tolerance.  相似文献   

2.
Forest insect pests are one of the major disturbance factors in forest ecosystems and their outbreaks are expected to be more severe under the influence of global warming. Coleopterans are dominant among forest insects and their ecological functions include general detritivores, dead wood feeders, fungivores, herbivores, live wood feeders and predators. Ambrosia and bark beetles contribute to ecological succession of forests and, therefore, ecological functions of forests can be changed in response to their outbreaks. Mountain pine beetle (MPB) outbreaks are the most dramatic example of changes in the ecological functions of forest due to the outbreak of a forest insect pest altered by global warming. Composition of coleopteran species varies with latitude. However, composition of functional groups is consistent with latitude which indicates that resources available to beetles are consistent. In coleopteran communities, ambrosia and bark beetles can become dominant due to increases of dead or stressed trees due to the warming climate. This can also induce changes in the ecological functions of coleopterans, i.e. selective force to displace trees that have lower ecological fitness due to temperature increase. Therefore, recent increases in the density ambrosia and bark beetles offer a chance to study ecological processes in forests under the influence of global warming.  相似文献   

3.
《Dendrochronologia》2014,32(2):113-119
Most subtropical forests in South America are located in regions with a marked seasonality in precipitation, which may induce the formation of annual bands in woody species. Due to the lack of precise information on tree-ring visibility, we evaluated the wood characteristics of 37 tree species in the subtropical Yungas and Chaco forests from northwestern (NW) Argentina. Anatomical features associated with the delimitation of growth bands were examined to establish the presence of tree rings. Different forest types reflect the precipitation gradients and wood anatomical features vary accordingly. Characteristics of wood structure are closely related to the dominant climatic patterns of each forest, revealing a common pattern of anatomical arrangements in terms of water transport and safety. In the Chaco and transitional forests, ring boundaries are related to marginal parenchyma whereas in montane forests growth ring boundary is mostly associated with the presence of thicker fibers at the end of the ring. The largest proportion of species with clearly marked growth rings occurs in the montane forest type of NW Argentina. Clear growth rings is a requisite for dendrochronological applications, hence the present work represents the first regional attempt to address the potential of subtropical species in South America to be used in dendrochronological studies.  相似文献   

4.
5.
We described, through a vegetation profile, the forest structure (density, basal area, tree height, and species composition), the productivity dynamics (based on litterfall) and the species phenology of distinct physiognomic types of mangroves in three locations of the La Mancha lagoon system in Veracruz, Mexico, during a complete annual cycle. We also evaluated the microtopography and ground water salinity along the profile and their relationship with forest structure and productivity. The South location showed four physiognomic types, whose forest attributes decreased as they were farther from the lagoon shore. Productivity and environment variables significantly varied among these physiognomic types. The Center location had two physiognomic types; there were significant differences in productivity and microtopography among these types, but not in salinity. The North location included two fragments of a basin forest type, and a pasture among them; productivity significantly varied among these forests, but microtopography and salinity were statistically similar. All study sites showed the following behavior: (1) as forest structure decreased, productivity also decreased and the dominant species changed. (2) As water salinity decreased, species dominance changed and productivity increased. Reproductive structures showed a notorious seasonality during the year in all species, except in R. mangle, which showed a permanent flower and propagules production. A. germinans reproduced only in the rainy season (August and September), because of their life history characteristics, whereas L. racemosa reproduced during the months of February and March as a response of the direct entrance of the water discharges, enriched with nutrients, that come from the sugar cane and rice crops. The South location was a relatively well conserved area, whereas the two other sites showed evidences of anthropic disturbances.  相似文献   

6.
Allen JA  Krauss KW  Hauff RD 《Oecologia》2003,135(1):110-121
The tree species Xylocarpus granatum is commonly described as occurring in the upper intertidal zone of mangrove forests, but mature trees are occasionally found at lower elevations. In the Utwe River basin, on the Pacific island of Kosrae, we investigated the relative importance of several biotic and abiotic factors that may control the intertidal distribution of X. granatum. Factors we evaluated included differential seed predation across the lower, mid, and upper intertidal zones and seedling responses to salinity, tidal flooding, and shade. Seed predation was 22.4% over the first 34 days and varied little among zones or in gaps versus under the forest canopy. By day 161, there were still no differences in seed mortality, but a significant difference was found in seedling establishment, with much greater establishment in the upper intertidal plots. X. granatum seedlings in a greenhouse experiment exhibited greater growth in freshwater than seedlings in 23 ppt salinity, which is typical of salinity levels found in the mid intertidal zone in our field study sites in Micronesia, where mature X. granatum trees are generally absent. Seedlings grown in 23 ppt salinity, however, exhibited few visible signs of stress associated with patterns in growth. Seedlings grown in a simulated tidal flooding treatment (with 23 ppt salinity) also showed few signs of stress. Growth declined dramatically under 80% shade cloths, but there were few interactions of shading with either 23 ppt salinity or simulated tidal flooding. Differential seed predation is not likely to be the primary factor responsible for the intertidal distribution of X. granatum on Kosrae. However, seedling tolerance of flooding or salinity may be more important, especially relative to a potential contribution to secondary stress mortality. Other factors may ultimately prove to be more critical, such as physiological effects of salinity on seed germination, effects of tides on seed dispersal and rooting, or differential herbivory on seedlings.  相似文献   

7.
Abstract. Within different stands of the white-water inundation forest (várzea forest) in the Central Amazon region, composition, abundance, frequency and basal area of tree species were recorded. Determinations of age and radial growth rates were conducted using dendrochronological methods. Results show significant differences in age, history and species composition between stands as well as different growth strategies among dominant species. Assignment of tree species to growth strategies by means of anatomical and morphological features together with quantitative aspects of vegetational analysis permit the further differentiation of successional stages of várzea forests. General features of successional stages were quantitatively described and compared with forest types from outside the várzea. Many tree species of the várzea forests are widespread in South America, and not limited to floodplains. Their occurrence on sites with distinct dry seasons suggests that they are not specifically adapted to flooding but are tolerant to seasonality in general.  相似文献   

8.

Mangrove tree species show plasticity in their leaf morphological traits in different salinity zones. However, leaf morphological plasticity and its causes in different salinity zones are incompletely understood. To understand the mechanism of plasticity, this study investigated the responses of three dominant tree species Sundri (Heritiera fomes), Gewa (Excoecaria agallocha) and Goran (Ceriops decandra) of the Sundarbans to the salinity gradients. A total of 17 leaf parameters were measured and quantified. All collected data were analyzed using univariate and multivariate statistical tools to investigate leaf morphological plasticity. A wide range of phenotypic plasticity was observed in all leaf parameters studied among the salinity zones of the Sundarbans. One-way ANOVA and Tukey’s posthoc test revealed significant differences (P?<?0.05) in all leaf parameters among the salinity zones and confirming that there was a high degree of phenotypic plasticity among the salinity zones of the Sundarbans. Petiole length (PL), leaf area (LA) and leaf length/petiole length (LL/PL) showed high level of plasticity among the salinity zones of the Sundarbans for each species of Sundri, Gewa and Goran. Plasticity index (PI) was developed in this study for each species studied. High level of phenotypic plasticity in these leaf traits reflects fitness of these species to different saline environments. Our results provide clear evidence that all the leaf parameters measured for three tree species viz., Sundri, Gewa and Goran effectively utilizes a plastic strategy in different salinity zones in the Sundarbans. Morphological trait plasticity could serve as powerful biological indicators to predict the shift of leaf morphology in upcoming environmental change events like sea level rise and reduction of fresh water flow from upstream.

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9.

Key message

Anatomical characteristics and hydrologic signals in tree-rings of oaks from areas with regular flooding may vary, even within the same forest stand, and largely depend on the micro-environmental conditions.

Abstract

Q. robur decline in European floodplain forests in recent years seems to be strongly associated with the deteriorating hydrological regime. We investigated the influence of the Krka River flow on tree-ring patterns of Q. robur from the Krakovo floodplain forests (Slovenia) to assess the effect of micro-location conditions on hydrological signals in wood-anatomical characteristics. We selected two groups of Q. robur trees growing at nearby locations with different hydrological conditions, resulting in frequent autumn and spring flooding at the wetter site (=W oaks) but no flooding at the other, drier site (=D oaks). We found differences between the two groups in the anatomical structure of tree-rings; however, ring width proved to be the main variable determining the anatomical structure of oak wood. D and W oaks responded differently to the Krka River flow in the studied period. Radial growth of D oaks was negatively influenced by spring flow, but positively influenced by minimum summer flow. In W oaks, ring width was positively correlated with mean summer flow. Thus, environmental information stored in wood-anatomical features may vary, even within the same forest stand, and largely depends on the micro-environment. Reduced wood increments of D oaks suggest that growth conditions are less favourable, implying a link between the health state of oaks from lowland forest and hydrological conditions. Trees intended for hydrological reconstruction must therefore be carefully selected to avoid the possibility of error and potential loss of information. Anatomical characteristics and hydrological signals in tree-rings of oaks from areas with regular flooding may vary, even within the same forest stand, and largely depends on the micro-environmental conditions.  相似文献   

10.
Sea-level rise threatens low-lying coastal ecosystems globally. In Florida, USA, salinity stress due to increased tidal flooding contributes to the dramatic and well documented decline of species-rich coastal forest areas along the Gulf of Mexico. Here, we present the results of a study of coastal forest stand dynamics in thirteen 400 m2 plots representing an elevation gradient of 0.58–1.1 m affected by tidal flooding and rising sea levels. We extended previously published data from 1992–2000 to 2005 to quantify the full magnitude of the 1998–2002 La Niña-associated drought. Populations of the dominant tree species, Sabal palmetto (cabbage palm), declined more rapidly during 2000–2005 than predicted from linear regressions based on the 1992–2000 data. Dramatic increases in Juniperus virginiana (Southern red cedar) and S. palmetto mortality during 2000–2005 as compared with 1995–2000 are apparently due to the combined effects of a major drought and ongoing sea-level rise. Additionally, coastal forest stands continued to decline in species richness with increased tidal flooding frequency and decreasing elevation. Stable isotope (H, O) analyses demonstrate that J. virginiana accesses fresher water sources more than S. palmetto . Carbon isotopes reveal increasing δ 13C enrichment of S. palmetto and J. virginiana with increased tidal flooding and decreased elevation, demonstrating increasing water stress in both species. Coastal forests with frequent tidal flooding are unable to support species-rich forests or support regeneration of the most salt-tolerant tree species over time. Given that rates of sea-level rise are predicted to increase and periodic droughts are expected to intensify in the future due to global climate change, coastal forest communities are in jeopardy if their inland retreat is restricted.  相似文献   

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