Manganese dynamics in a mangrove mud flat tidal creek in SE Brazil

This study investigated the behavior of soluble and particulate manganese, during tidal cycles in a mangrove tidal creek and adjacent mud flats in SE Brazil. We identify the major processes affecting manganese transport to mangroves. The results showed that manganese variability occurs both seasonally, and over the tidal cycle, in response to changing redox potentials. Tidal water flooding mud flats are enriched in manganese, originating from upward migration of reduced species and further adsorption onto suspended particles under oxic conditions. During the tidal cycle, particulate manganese concentrations are higher during flood periods, whilst dissolved concentrations are higher during ebb periods. Although quantitatively different, this pattern occurs both in winter and summer. The dynamics of manganese characterized in this study suggest that this metal may play a significant role as a conveyor of trace metals to mangrove ecosystems, as suggested by earlier studies.     

Vertical accretion and shallow subsidence in a mangrove forest of southwestern Florida,U.S.A.

Simultaneous measurements of vertical accretion from artificial soilmarker horizons and soil elevation change from sedimentation-erosion table(SET) plots were used to evaluate the processes related to soil building infringe, basin, and overwash mangrove forests located in a low-energy lagoonwhich receives minor inputs of terrigenous sediments. Vertical accretionmeasures reflect the contribution of surficial sedimentation (sedimentdeposition and surface root growth). Measures of elevation change reflectnot only the contributions of vertical accretion but also those ofsubsurface processes such as compaction, decomposition and shrink-swell. Thetwo measures were used to calculate amounts of shallow subsidence (accretionminus elevation change) in each mangrove forest. The three forest typesrepresent different accretionary environments. The basin forest was locatedbehind a natural berm. Hydroperiod here was controlled primarily by rainfallrather than tidal exchange, although the basin flooded during extreme tidalevents. Soil accretion here occurred primarily by autochthonous organicmatter inputs, and elevation was controlled by accretion and shrink-swell ofthe substrate apparently related to cycles of flooding-drying and/or rootgrowth-decomposition. This hydrologically-restricted forest did notexperience an accretion or elevation deficit relative to sea-level rise. Thetidally dominated fringe and overwash island forests accreted throughmineral sediment inputs bound in place by plant roots. Filamentous turfalgae played an important role in stabilizing loose muds in the fringeforest where erosion was prevalent. Elevation in these high-energyenvironments was controlled not only by accretion but also by erosion and/orshallow subsidence. The rate of shallow subsidence was consistently3–4 mm y^–1 in the fringe and overwash island forests butwas negligible in the basin forest. Hence, the vertical development ofmangrove soils was influenced by both surface and subsurface processes andthe processes controlling soil elevation differed among forest types.The mangrove ecosystem at Rookery Bay has remained stable as sea levelhas risen during the past 70 years. Yet, lead-210 accretion data suggest asubstantial accretion deficit has occurred in the past century (accretionwas 10–20 cm < sea-level rise from 1930 to 1990) in the fringe andisland forests at Rookery Bay. In contrast, our measures of elevation changemostly equalled the estimates of sea-level rise and our short term estimatesof vertial accretion exceeded the estimates by the amount of shallowsubsidence. These data suggest that (1) vertical accretion in this system isdriven by local sea-level rise and shallow subsidence, and (2) the mangroveforests are mostly keeping pace with sea-level rise. Thus, the vulnerabilityof this mangrove ecosystem to sea-level rise is best described in terms ofan elevation deficit (elevation change minus sea-level rise) based on annualmeasures rather than an accretion deficit (accretion minus sea-level rise)based on decadal measures.     

Distribution and fluxes as macrodetritus of phosphorus in red mangroves, Sepetiba Bay, Brazil

The distribution and dynamics of phosphorus have been studied in the mangroves of Sepetiba Bay, Brazil. Leaf fall contributes 3.0 kg P ha=¹yr=¹to the sediment. The total above ground biomass of the R. mangle stand was about 65.3 t ha=¹, the P accumulation was 3.9 kg P ha=¹where 63% of the total P-biomass was accumulated in the leaves. The biomass of below ground roots was about 8.2 tha=¹ and accumulated 16% of total P-biomass. Sediment contained 452 kg P ha=¹ where P combined with calcium (P-Ca) was the main fraction (260 kg ha=¹). The annual flux of P as litter fall was small (< 1%) compared to total P in the sediment reservoir. The annual export of P by macrodetritus corresponds to 0.05% of the total sediment reservoir.     

Sediment mixing and accumulation in a mangrove ecosystem: evidence from 210Pb, 234Th and 7Be

210Pb, 234Th and 7Be activities were measured to establish sediment accumulation rates, estimate sediment mixing rates, and determine the depth of the sediment mixed layer in the Sepetiba Bay mangrove ecosystem near Rio de Janeiro City, Brazil. Three sediment cores were collected from Enseada das Garças, a typical exposed tidal flat region with a sequence of sedimentary features. The seaward edge of this sequence is a mud flat with the landward portion covered with Spartina alterniflora followed by mangrove vegetation. An additional core was collected on an overwash island near Barra de Guaratiba, which is cover with mangroves without a mud flat or Spartina alterniflora sequence. Sediment accumulation rates were determined to range up to 1.8cm/yr with the Spartina alterniflora having the maximum rate. Mixing rates were estimated for the Spartina alternifloracore at 40cm2/yr based on 210Pb and 7Be from the upper mixed region of the core. The 234Th activity in this core suggested that either mixing or the input of 234Th were not in steady state. The sediment mixed region depth ranged from 4cm to greater than 30cm. At the Enseada das Garças site the mixing depth decreased in the landward direction (i.e. mud flats > 30cm, Spartina alterniflora 11cm, mangroves 4cm). Along with this decrease in sediment mixing depth was a shift from physical to biological mixing. The Barra de Guaratiba core had a sediment mixed layer of 13cm as a result of physical and intense biological activity.     

Restoration of the mangrove vegetation in the Mahanadi delta,Orissa, India

In India, mangroves occupy 6740 km² of which the Mahanadi delta andBhitarkanika mangrove forests of Orissa cover 191.44 km², most of whichhas been severely overexploited. World wide concern to conserve mangrovesnecessitated propagation of mangroves to re-establish them on barren andswampy land along tidal creeks around Paradeep port of Orissa. Avicenniaofficinalis, Aegiceras corniculatum, Bruguiera parviflora, B. sexangula,Ceriops decandra, Excoecaria agallocha, Heritiera fomes, Kandelia candel,Rhizophora mucronata, Sonneratia apetala were vegetatively propagated andplanted over 10 ha of degraded salt-marshy wetlands of Mahanadi delta inpure and mixed stands depending on the intensity and the frequency of tidalinundation at the experimental site. Survival was significantly higher(80%) in S. apetala followed by A. officinalis, R. mucronata, K.candel and H. fomes (70–75%). S. apetala recorded the maximumgrowth in height (3.0 m after 2 years) whereas C. decandra showed theminimum growth (0.5 m). Growth performance was better with plants in mixedstands than the plantation with single species. This gives us hope topropagate and re-establish mangroves for conservation in scientificallymanaged plantations in a physiologically arid environment.     

Nutrient dynamics in a mangrove creek (North Brazil) during the dry season

During the dry season, dissolved inorganic nutrients and organic carbon (DOC) in a mangrove tidal creek (Bragança, North Brazil) presented a clear tidal signature: silicate, phosphate, ammonium and DOC covaried with salinity, with minima at high tide and maxima at low tide. Hydrodynamical calculations explained most diel variability as dilution of nutrientrich groundwater input by estuarine water. Creek nutrients tended to lower concentrations towards the end of the dry season, probably due to changes in groundwater dynamics. Ammonium was about 44% higher in the night than during the day, while silicate, phosphate nitrate + nitrite showed differences < 5%, indicating preferential autotrophic uptake of ammonium as nitrogen source. Nitrification and/or nitrogen fixation are probably sources of nitrate + nitrite, which contributed only 12% to the dissolved inorganic nitrogen pool. Dissolved oxygen (7%) and DOC (11%) were lower during the night, suggesting the existence of a labile, algalderived DOC pool. There is a loose coupling between aquatic primary production, groundwater dynamics and tidal regime.     

深圳湾福田保护区红树林生态系统服务功能价值评估

对深圳湾福田保护区红树林的生态服务功能价值进行了研究,结果表明:深圳湾福田保护区现有生态系统服务功能年总价值4 894.4万元,深圳湾红树林湿地生态系统单位面积生态功能价值约10.74万元/hm2a,其中红树林价值2 702.4万元,河道价值282万元,淤泥滩涂价值674万元,海域价值1 840万元,基建填土区观光旅游价值260万元,林地价值76万元。深圳湾福田保护区红树林生态系统服务功能价值中,生产生态系统产品等9个分项的总和为2 928万元。对环境氮与磷的去除价值、重金属吸附价值、二氧化碳固定和氧气释放价值等在内的生态系统净化功能价值共占14.2%。深圳湾的所有红树林类型中,秋茄+桐花树+白骨壤生态系统类型单价最大值为12.3万/hm2a。深圳市梧桐山森林生态系统服务功能价值为1.076 4～1.148 4万元/hm2a,显著低于本研究红树林生态系统服务功能价值,约占单位面积红树林生态系统的生态价值10%。香港米埔红树林生态系统的生态服务功能价值(13.7万港元/hm2a)高于深圳湾红树林生态系统,约高出21%。改造后的深圳湾生态系统服务功能价值预期可达7 243.48万元。     

Extensive shrimp farming,mangrove clearance and marine fisheries in the southern provinces of Vietnam

Within the last decade shrimp farming in the Mekong Delta of Vietnam has increased by 3500%. Shrimp farming became un-sustainable in the early 1990's due to the un-planned development of this industry and the resulting self pollution of the farms, the destruction of mangrove forest and the outbreak of viral diseases. Historical data on fisheries, fishing effort and mangrove coverage were obtained from the province Minh Hai (lately divided in Ca Mau and Bac Lieu). Analysis of catch and effort data of marine fisheries in the Mekong Delta indicated a severe danger of over-exploitation of fish stocks and further decline can be expected if fisheries management only considers the demand for fish. The relation between the total fish catch (t/year), the mangrove area (ha), the engine capacity (HP) of the fishing fleet and the social incentive for fishing could be described with the model: Total catch=0.449*Mangrove area + 0.614 Engine capacity + 654 Social factor. One hectare of mangrove forest supports a marine catch of 450 kg/year     

Effects of roads,topography, and land use on forest cover dynamics in the Brazilian Atlantic Forest

Roads and topography can determine patterns of land use and distribution of forest cover, particularly in tropical regions. We evaluated how road density, land use, and topography affected forest fragmentation, deforestation and forest regrowth in a Brazilian Atlantic Forest region near the city of São Paulo. We mapped roads and land use/land cover for three years (1962, 1981 and 2000) from historical aerial photographs, and summarized the distribution of roads, land use/land cover and topography within a grid of 94 non-overlapping 100 ha squares. We used generalized least squares regression models for data analysis. Our models showed that forest fragmentation and deforestation depended on topography, land use and road density, whereas forest regrowth depended primarily on land use. However, the relationships between these variables and forest dynamics changed in the two studied periods; land use and slope were the strongest predictors from 1962 to 1981, and past (1962) road density and land use were the strongest predictors for the following period (1981–2000). Roads had the strongest relationship with deforestation and forest fragmentation when the expansions of agriculture and buildings were limited to already deforested areas, and when there was a rapid expansion of development, under influence of São Paulo city. Furthermore, the past (1962) road network was more important than the recent road network (1981) when explaining forest dynamics between 1981 and 2000, suggesting a long-term effect of roads. Roads are permanent scars on the landscape and facilitate deforestation and forest fragmentation due to increased accessibility and land valorization, which control land-use and land-cover dynamics. Topography directly affected deforestation, agriculture and road expansion, mainly between 1962 and 1981. Forest are thus in peril where there are more roads, and long-term conservation strategies should consider ways to mitigate roads as permanent landscape features and drivers facilitators of deforestation and forest fragmentation.     

Valuation and characterization of the timber species in remnants of the Alto Uruguay River ecosystem,southern Brazil

Turvo Park in the Alto Uruguay River region of the State of Rio Grande do Sul is the last intact remnant of the Seasonally Deciduous Forest in southern Brazil. This forest once covered large parts of southern Brazil but it is now reduced to less than 3% of its original size due to intensive logging caused by its exceptional richness in tree species with commercial timber value. The current study presents results on the diversity of timber species inventored in Turvo Park and in a number of small and scattered forest remnants in its vicinity. All timber plants with DBH ≥5 cm were included in the forest inventory on 540 sampling points, established using the point-centred quarter method. On average, 313 plants ha⁻¹ were recorded, belonging to 57 different species from 25 families. Timber species of commercial value represented 64% of all woody species and 36% of all woody plants. Nectandra megapotamica and Apuleia leiocarpa were the main dominant species. Twenty percent of all plants showed a DBH greater than 40 cm, representing 67% of the total log volume. Differences in species diversity and plant density among the forest remnants were detected. The few forest remnants represent an enormous richness of timber species, being the maintainers and propagule repository for all the biodiversity of that ecosystem. A knowledge-based forest management plan is therefore required to secure their vital role in forest enrichment programs or in projects aiming at recovering abandoned and degraded areas, and in breeding programs for the timber production improvement.     

地下水除铁除锰设计探讨

本文简述了地下水除铁除锰的工作原理,并结合自己在地下水除铁除锰工作中的工程实践,探讨了在设计过程中应注意的问题。     

Complexity and variety of zonal pattern in the mangroves of the Hinchinbrook area, Northeastern Australia

Hinchinbrook Island, a wilderness National Park, lies closely adjacent to the Australian mainland within the boundaries of the Great Barrier Reef World Heritage area. The mangroves that occupy much of its shoreline and the neighbouring mainland intertidal are major features. Recent preliminary surveys have revealed considerable floristic variety at local scales and, over the total area, often intricate vegetal patterning (Bunt, 1997). It is the intention now to define the most conspicuous features in numeric and graphical terms. Particular attention has been given to differences in shore normal species sequencing within the study area and to the complexities associated with overlap in species distributions.     

The Formation of Tidal Creeks in a Salt Marsh: New Evidence from the Loyola Bay Salt Marsh,Rio Gallegos Estuary,Argentina

A mechanism is proposed for the Formation of tidal creeks in salt marshes which is exemplified by the marshes of the Rio Gallegos estuary, Argentina. It has been observed that salt pans are elongated in the mean wind direction and are likely to extend by wave erosion of the surrounding marshes. Interconnection between the pans leads to growth and interaction with existing creeks and channels. Tidal exchange of the waters then promotes further erosion, or subsequently to filling in by the introduced suspended sediment. This mechanism contrasts with headward erosion by existing creeks.     

浙江苍南沿浦湾秋茄人工林早期生长特征研究

目的 比较福建九龙江、云宵和广东深圳3个种源7个样地秋茄的生长差异,凝练种苗采购和宜林地选择技术。 方法 基于7个样地的数据,采用方差分析、多重比较及回归分析研究秋茄株高与地径、叶片数量之间的关系。 结果 7个样地的秋茄生长存在一定的差异,向陆林区样地A的秋茄平均株高、地径和叶片数比向海样地D的大,非潮沟边样地C的秋茄较比邻潮沟中间样地B的生长好,互花米草区样地E的秋茄比向陆样地A的生长差;秋茄株高与地径、叶片的二元线性回归模型为Y = −2.941+26.785X1 + 0.047X2（R2＝0.872,P < 0.01）,二元非线性回归模型为Y = −356.815 + 26.396X1 + 340.407X20.01（MS = 0.875,P < 0.01）;株高与地径的一元线性回归模型为Y = −48.961 + 89.203X1 − 23.88X12 + 2.548X13（R2＝0.941,P < 0.01）,一元非线性模型为Y = 289.888X1/（X1 + 8.913）（MS = 3.626,P < 0.01）;福建云霄种源秋茄比九龙江和广东深圳的更适宜引种在沿浦湾。 结论 秋茄宜林地应选在水动力较弱的滩涂区,潮沟边缘栽种前应适当改造生境,以减小潮流的冲击;互花米草区需在清除后较长时间方可栽种秋茄;向海林区边缘造林时应采取措施减小潮水和藤壶等污损生物的胁迫影响;种苗采购应选择与拟栽种区气候较接近的种源地。     

Tree planting by small producers in the tropics: A comparative study of Brazil and Panama

Forest regrowth is a notable phenomenon across the tropical forest latitudes. Such reforestation takes place in the wake of land abandonment, occurs cyclically in a rotational agricultural system, and may result from the deliberate planting of trees by farmers. Although less extensive than successional forest regeneration, tree planting by small farmers can have potentially important environmental impacts at both the site and global scale. This paper examines tree-planting efforts by small farmers in the tropical frontier regions of Panama and Brazil in order to gauge the magnitude of reforestation activities, and to identify factors that influence these efforts. This paper discusses the environmental regulations, forestry law, and tenure institutions in both countries, and performs a comparative analysis of reforestation efforts with information derived from household surveys (n = 356) and in-depth tree planting interviews (n = 35). Results from logistic regression are also presented. Our results show that tree planting occurs more frequently in Panama, which we attribute to greater external support in the provisioning of extension and materials and strong market incentives. We suggest that the proximity of the study sites to Panama City facilitates external support and market drivers. Finally, our results suggest that land tenure security is an influential determinant of reforestation activities in both countries.This revised version was published online in November 2005 with corrections to the Cover Date.     

巴西半干旱地区自然条件和菌根菌接种条件下赤桉和大桉地上生物量营养成分分析(英文)

对巴西米纳斯吉拉斯州北部半干旱地区(15°09’S43°49’W)的赤桉(Eucalyptus camaldulensis)和大桉(Eucalyptus grandis)人工林的地上生物量、营养成分含量和菌根菌定植百分率进行了调查和分析。结果表明,赤按和大桉人工林的总地上生物量分别为33.6Mg·hm-2和153.1Mg·hm-2。赤桉树干、叶子、枝条和树皮的生物量分别占总生物量的64.4%,19.6%,15.4%,0.6%,大桉地上生物量的分配与赤按基本相同。赤桉叶子和枝条的干物质占其总生物量的35%,叶子和枝条中的N,P,K,Ca,Mg,and S的含量分别占总生物量这些营养元素的15.5%,0.7%,12.3%,22.6%,19%,1.4%。树干(包括树皮)中的营养成分累积相对比较低。与赤桉相比,大桉的营养含量变化较小。这2个树种的树干上部含有高浓度的磷,树皮也含有大量的营养物质,尤其是大桉;说明在半干旱地区,立地上脱落的植物性废物对降低树木生产力损失有重要意义。赤桉和大桉都有菌根营养。     

Aboveground nutrient components of Eucalyptus camaldulensis and E. grandis in semiarid Brazil under the nature and the mycorrhizal inoculation conditions

A study was conducted to evaluate the aboveground biomass, nutrient content and the percentages of mycorrhizal colonization in Eucalyptus camaldulensis and Eucalyptus grandis plantations in the semiarid region (15° 09′ S 43° 49′ W) in the north of the State of Minas Gerais in Brazil. Results show that the total above-ground biomass (dry matter) was 33.6 Mg·ha⁻¹ for E. camaldulensis and 53.1 Mg·ha⁻¹ for E. grandis. The biomass of the stem wood, leaves, branches, and stem bark for E. camaldulensis accounted for 64.4%, 19.6%, 15.4%, and 0.6% of the total biomass, respectively (Table 2); meanwhile a similar partition of the total above-ground biomass was also found for E. grandis. The dry matter of leaves and branches of E. camaldulensis accounted for 35% of total biomass, and the contents of N, P, K, Ca, Mg, and S in leaves and branches accounted for 15.5%, 0.7%, 12.3%, 22.6%, 1.9%, and 1.4% of those in total above-ground biomass, respectively. In the trunk (bark and wood), nutrient accumulation in general was lower. Nutrient content of E. grandis presented little variation compared with that of E. camaldulensis. Wood localized in superior parts of trunk presented a higher concentration of P and bark contained significant amounts of nutrients, especially in E. grandis. This indicated that leaving vegetal waste is of importance on the site in reducing the loss of tree productivity in this semi-arid region. The two species showed mycotrophy.     

Seasonal dynamics of wood formation: a comparison between pinning,microcoring and dendrometer measurements

Three different methods were evaluated for analysing wood formation of Norway spruce [Picea abies (L.) Karst.] and Scots pine (Pinus sylvestris L.) in Finland. During two growing seasons, wood formation dynamics were determined both by wounding the cambium with a needle followed by localisation of the wound-associated tissue modification after the growing season (pinning), and by extracting small increment cores during the growing season (microcoring). Stem radius was additionally monitored with band dendrometers. For Norway spruce, pinning and microcoring yielded similar dates for the onset of wood formation. The timing of wood production during the growing season was also similar for pinning and microcoring. For Scots pine, the onset of wood formation was recorded from microcores almost 2 weeks later than from pinning samples. In Scots pine, microcore measurements also produced somewhat later cessation dates for tracheid formation than the pinning samples. For both tree species, the total number of tracheids formed during the growing season was, however, about the same for pinning and microcoring. Dendrometer results clearly differed from those of pinning and microcoring. In particular, the dendrometers showed an increase of stem radius considerably earlier in spring, when the other methods did not detect wood formation. Thus, pinning and microcoring currently represent the most reliable techniques for detailed monitoring of wood formation.     

Trends in allometric models and aboveground biomass of family Rhizophoraceae mangroves in the Coral Triangle ecoregion,Southeast Sulawesi,Indonesia

This study aims to establish allometric models and estimate aboveground biomass (AGB) of mangroves Rhizophoraceae in the Southeast Sulawesi, Indonesia. Allometric models of the AGB of mangroves Rhizophora apiculata, R. mucronata, and Ceriops tagal were established using independent variables consisting stem diameter at 30 cm from the ground (D₃₀), diameter at breast height (DBH), D₃₀²H and DBH²H. The AGB of mangroves was estimated by applying allometric model and tree census. The results showed that the best fitting allometric models of AGB for R. apiculata is based on variable DBH, while DBH²H is the best variable for R. mucronata trees. Conversely, the D₃₀ is the best variable for estimating AGB of C. tagal trees. Thus, there is some variation of independent variables on allometric models for the estimation of AGB for Rhizophoraceae mangroves. The AGB (ton ha^?1) of R. apiculata, R. mucronata, and C. tagal was estimated respective 651.60, 232.11 and 154.56 in the protected area, and respective 137.59, 189.35 and 39.06 ton ha^?1 in the unprotected area. Higher AGB of mangroves growing in the protected area indicated the suitable condition and undisturbed by human activities. The conservation of mangroves is necessary for the sustainability of mangroves and coastal ecosystems in the Coral Triangle ecoregion.     

Burning of Amazonian forest in Ariquemes, Rondônia, Brazil: biomass, charcoal formation and burning efficiency

Biomass burning in tropical forests – the normal practice to prepare land for agriculture and ranching – has been a major source of CO₂ emitted to the atmosphere. Mass transformations by burning are still little studied in the tropics. The present study estimated parameters, such as the stock of carbon contained in the biomass, burning efficiency and the formation of charcoal and ashes in a tropical moist forest. Two sets of plots arranged in the form of ‘stars' (720 m² total) were installed in a 3.5 ha area of forest that had been felled for planting pasture at Fazenda Nova Vida, Ariquemes, Rondônia. Each ‘star' had six rays measuring 2 m × 30 m; alternating rays were designated for pre-burn and post-burn measurements. All above-ground biomass present in the plots was weighed directly before the burn in the pre-burn rays and after the burn in the post-burn rays. Pieces of wood with diameter ≥10 cm also had their biomasses estimated from volume estimates, using line-intersect sampling (LIS) in order to increase the area of sampling and to allow volume loss to be estimated as an increment based on individual pieces measured before, and after, the burn at the same point (as opposed to inferring change as a difference between independent estimates of stocks). The initial above-ground biomass (dry weight) before the burn was estimated at 306.5 ± 48.6 (mean ± SE) Mg ha⁻¹, with an additional 4.5 Mg ha⁻¹ for trees left standing. Carbon stock in the initial biomass (including trees left standing) was 141.3 (Mg C) ha⁻¹. After burning, carbon stock was reduced by 36.8% (burning efficiency). The stocks of charcoal and ash formed in the burn were, respectively, 6.4 ± 2.7 and 5.7 ± 1.0 Mg ha⁻¹. The destructive and nondestructive (LIS) methods did not differ significantly (t-test, p > 0.05) in estimating post-burn stocks of wood and charcoal. The results of this study contribute to improving the estimates of parameters needed for global carbon calculations and point to ways in which estimates of these parameters could be further improved.