Carbon sequestration in tropical forests and water: a critical look at the basis for commonly used generalizations

Tree planting in the tropics is conducted for a number of reasons including carbon sequestration, but often competes with increasingly scarce water resources. The basics of forest and water relations are frequently said to be well understood but there is a pressing need to better understand and predict the hydrological effects of land‐use and climate change in the complex and dynamic landscapes of the tropics. This will remain elusive without the empirical data required to feed hydrological process models. It is argued that the current state of knowledge is confused by too broad a use of the terms ‘forest’ and ‘(af)forestation’, as well as by a bias towards using data generated mostly outside the tropics and for nondegraded soil conditions. Definitions of forest, afforestation and reforestation as used in the climate change community and their application by land and water managers need to be reconciled.     

The importance of water regimes operating at small spatial scales for the diversity and structure of wetland vegetation

1. In most cases, the most important determinant of wetland vegetation is the water regime. Although water regime is usually described and managed at the scale of whole wetlands, the patterning of vegetation is likely to be determined by water regimes that are experienced at much finer spatial scales. In this study, we assess the significance of internal heterogeneity in water regimes and the role that this heterogeneity plays in vegetation patterning. 2. The effects of water regime on wetland plant species richness and vegetation structure were studied at Dowd Morass, a 1500 ha, Ramsar‐listed wetland in south‐eastern Australia that is topographically heterogeneous. Data on plant variables and water depth were collected along 45 (50 m) transects throughout the wetland and related to water regimes assigned individually for each transect. Wetland plants were assigned to plant functional groups (PFG) that describe the response of plants to the presence or absence of water at different life stages. 3. The classification of water depth data indicated four distinct water regimes in the wetland that were differentiated primarily by the duration of the dry period. Representatives of all PFGs co‐existed over small spatial scales where topographical variation was present, and the richness and cover of understorey species declined as transects became more deeply and permanently flooded. Some PFGs (e.g. amphibious fluctuation tolerator‐low growing and amphibious fluctuation responder‐morphologically plastic) were eliminated by extended periods of flooding, which increased the cover but not richness of submerged plants. Species richness and foliage projective cover declined as water regimes shifted from shallow and frequently exposed conditions to regimes typified by deeper and longer inundation. Cover of the structurally dominant woody species was compromised by deeply flooded conditions but vegetative regeneration occurred despite high water levels. 4. Internal topographical variation generates mosaics of water regimes at fine spatial scales that allow plant species with different water regime requirements to co‐exist over small distances. Deep water and an absence of dry periods result in decreased cover of plants and an overall loss of species richness in the understorey. Water regimes are described that promote regeneration and cover of structurally dominant taxa and increased species richness in the understorey. The study demonstrates a strong association between vegetation and the diverse water regimes that exist within a single wetland, a pattern that will be useful for modelling the effects of modified water regimes on wetland vegetation.     

Regret‐Regression for Optimal Dynamic Treatment Regimes

Summary We consider optimal dynamic treatment regime determination in practice. Model building, checking, and comparison have had little or no attention so far in this literature. Motivated by an application on optimal dosage of anticoagulants, we propose a modeling and estimation strategy that incorporates the regret functions of Murphy (2003, Journal of the Royal Statistical Society, Series B 65, 331–366) into a regression model for observed responses. Estimation is quick and diagnostics are available, meaning a variety of candidate models can be compared. The method is illustrated using simulation and the anticoagulation application.     

Conserving the Himalayan forests: approaches and implications of different conservation regimes

The conservation of Himalayan forests is big concern in view of global agenda. Many studies in this endeavor reported that the rate of forests degradation is posing a severe threat to the landscape and existing biodiversity in the Himalayas. Currently there many conservation approaches exists and of them four are widely recognized (1) Conservation through traditional religious beliefs “traditional conserved forests” (TCF); (2) Conservation through governmental planning and schemes “government conserved forests” (GCF); (3) Conservation through creation of protected areas (PAF); and (4) Conservation through community efforts “community conserved forests” (CCF). Our hypothesis in this direction says that all the conservation approaches lead to same results concerning to forest conservation. To testify our hypothesis we have studied the forests of each conservation regimes and evaluated them based on the identified indicators. We have done empirical studies and following the cloud-free satellite data were used for last three decades (such as Multi-Spectral Scanner, Linear Imaging and Self Scanning, and Enhanced Thematic Mapper ) to study a change in vegetation dynamics of the mountain forests in multi-temporal dimension. Our research concluded that community conservation approach have greater significance for biodiversity conservation and management in the Himalayan region. Here we support the model of CCF for forest ecosystem conservation, alongside the sustainable livelihood of the mountain societies. But every conservation regimes has its own importance in viewpoint of the particular objectives. Therefore, we suggests advancement and revision of PAF and GCF however, some elements of CCF can be introduced in TCF for making up it more sound in view of rapid socio-economic and cultural changes taking place in the communities. An erratum to this article can be found at     

Influence of biotic and abiotic factors on the persistence of a Beauveria bassiana biopesticide in laboratory and high-rise poultry house settings

Recent studies suggest the potential for use of oil formulations of the entomopathogenic fungus, Beauveria bassiana, as residual sprays for control of house flies in poultry production facilities. The current study investigated the influence of biotic and abiotic factors on biopesticide persistence. We found that flies physically removed and deactivated conidia, with higher fly densities and greater cumulative exposure hastening the decline. Nonetheless, very low densities of viable conidia were still able to cause rapid mortality, suggesting the potential for relatively long re-treatment intervals as fly populations are controlled. Considering abiotic factors, we found that fungal spray treatments remained viable for up to 13 weeks under laboratory conditions. Periodic exposure of flies to the spray residue showed high levels of mortality, with very little decline in mortality rate over time. Equivalent treatments placed in a commercial poultry house showed much more rapid decline. One trial at the end of summer showed conidia to remain viable up to seven weeks. However, repeats during the winter months revealed decay in 1–2 weeks, with fly mortality rates influenced accordingly. The exact reasons for the more rapid decay remain unclear but could be linked to high concentrations of ammonia in the basement areas, especially during winter when ventilation is minimal. The combined data suggest the potential for adaptive treatment regimes with weekly spray intervals in conditions with very high fly populations and/or high ammonia levels, and potentially monthly spray intervals when fly populations and ammonia levels are reduced.     

屋面绿化卷材根系层土壤温度变化特征

根据3种厚度屋面绿化卷材根系层土壤温度、自然条件下的土壤温度和附近气象站大气温度观测资料,采用对比分析、线性回归等方法,对不同屋面绿化卷材根系层土壤温度的变化特征进行了研究。结果表明:屋面绿化卷材根系层土壤温度年变化规律与大气温度年变化规律基本一致;卷材具有一定的隔热保温作用,且随着薄膜厚度的增加,绿化卷材保温隔热效果越明显;不同型号卷材根系层土壤温度的日变幅随薄膜厚度的增加而减小;根系层土温日变幅与厚度关系可拟合成指数函数;不同厚度屋面卷材根系层土壤温度同大气温度之间均存在极显著的线性关系。     

Temporal and spatial distribution of young Brachyplatystoma spp. (Siluriformes: Pimelodidae) along the rapids stretch of the Madeira River (Brazil) before the construction of two hydroelectric dams

Monthly (April 2009 to May 2010) bottom‐trawl sampling for Brachyplatystoma species along the rapids stretch of the Madeira River in Brazil revealed that Brachyplatystoma rousseauxii larvae and juveniles were present in low abundances in all areas and during all hydrological periods. The presence of larvae and juveniles throughout the hydrological cycle suggests asynchronous spawning in the headwaters of the Madeira River.     

连栽第1代和第2代杉木近熟林水文过程养分动态比较

利用小集水区径流场技术和定位研究方法,在获得连栽两代杉木近熟林的大气降水、穿透林冠水、地表、地下径流量等水文学数据,并测定其养分含量的基础上,研究了连栽两代杉木近熟林水文过程的营养动态特征。结果表明:降水中养分浓度第2代林比第1代林高20.30%—39.64%,养分的输入量比第1代多38.52%;穿透水中养分浓度,第1代和第2代林分别比大气降水中高4.149—4.895 g/kg和4.271—5.605g/kg,雨水对冠层营养物质的淋溶,第2代比第1代高2.94%—21.37%;地表径流中的养分浓度两代林差异不大,地下径流中的养分浓度第2代林比第1代高48.06%—78.87%,径流输出的养分量第2代林是第1代林的1.58—2.61倍;养分地球化学循环中,第1代林养分地球化学循环速率26.75%—29.95%,第2代林37.24%—47.43%,养分地球化学循环的周期第1代林3.3—3.7a,第2代林2.1—2.7a,养分地球化学循环中第2代林的养分流失率是第1代林的1.30—1.72倍,养分的净积累率只有第1代林的73.57%—87.14%。系统持留与利用由外界输入的养分功能上,第2代林低于第1代林。