Assessing regulating and provisioning ecosystem services in a contrasting tropical forest landscape

Ecosystem services are the bridge between nature and society, and are essential elements of community well-being. The Wet Tropics Australia, is environmentally and biologically diverse, and supplies numerous ecosystem services. It contributes to the community well-being of this region, Australian national economy and global climate change mitigation efforts. However, the ecosystem services in the region have rarely been assessed undermining strategic landscape planning to sustain their future flow. In this study, we attempted to: (i) assess the quantity of five regulating ecosystem services – global climate regulation, air quality regulation, erosion regulation, nutrient regulation, and cyclone protection, and three provisioning ecosystem services – habitat provision, energy provision and timber provision across rainforests, sclerophyll forests and rehabilitated plantation forests; (ii) evaluate the variation of supply of those regulating and provisioning ecosystem services across environmental gradients, such as rainfall, temperature, and elevation; (iii) show the relationships among those ecosystem services; and (iv) identify the hotspots of single and multiple ecosystem services supply across the landscape. The results showed that rainforests possess a very high capacity to supply single and multiple ecosystem services, and the hotspots for most of the regulating and provisioning ecosystem services are found in upland rainforest followed by lowland rainforest, and upland sclerophyll forest. Elevation, rainfall and temperature gradients along with forest structure are the main determinant factors for the quantity of ecosystem services supplied across the three forest types. The correlation among ecosystem services may be positive or negative depending on the ecosystem service category and vegetation type. The rehabilitated plantation forests may provide some ecosystem services comparable to the rainforest. The results demonstrated disturbance regimes (such as tropical cyclones) may have influenced the usual spatial trend of ecosystem service values. This study will assist decision makers in incorporating ecosystem services into their natural resource management planning, and for practitioners to identify the areas with higher values of specific and multiple ecosystem services.     

Complexity within an oil palm monoculture: The effects of habitat variability and rainfall on adult dragonfly (Odonata) communities

Recent expansion of oil palm agriculture has resulted in loss of forest habitat and forest-dependent species. However, large numbers of species—particularly insects—can persist within plantations. This study focuses on Odonata (dragonflies and damselflies): a charismatic indicator taxon and a potentially valuable pest control agent. We surveyed adult Odonata populations biannually over three years within an industrial oil palm plantation in Sumatra, Indonesia. We assessed the effects of rainfall (including an El Niño Southern Oscillation-associated drought), the role of roadside ditches, and the importance of understory vegetation on Odonata populations. To assess the impacts of vegetation, we took advantage of a long-term vegetation management experiment that is part of the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme. We found 41 Odonata species, and communities varied between plantation core and roadside edge microhabitats, and between seasons. Abundance was significantly related to rainfall levels four months before surveys, probably indicating the importance of high water levels in roadside ditches for successful larval development. We found no significant effect of the BEFTA understory vegetation treatments on Odonata abundance, and only limited effects on community composition, suggesting that local understory vegetation structure plays a relatively unimportant role in determining communities. Our findings highlight that there are large numbers of Odonata species present within oil palm plantations and suggest that their abundance could potentially be increased by maintaining or establishing waterbodies. As Odonata are predators, this could bring pest control benefits, in addition to enhancing biodiversity within intensive agricultural landscapes.     

Binucleation to breed new plant species adaptable to their environments

Classical plant breeding approaches may fall short to breed new plant species of high environmental and ecological interests. Biotechnological and genetic manipulations, on the other hand, may hold more effective capabilities to circumvent the limitations of sexual incompatibility and conventional breeding programs. Given that plant cells encompass multiple copies of organellar genomes (mitochondrial and plastidial genomes), an important question could be raised about whether an artificial attempt to duplicate the nuclear genome might also be conceivable through a binucleation approach (generating plant cells with 2 nuclei from 2 different plant species) for potential production of new polyploidies that would characterize new plant species. Since the complexities of plant genomes are the result of multiple genome duplications, an artificial binucleation approach would thus be of some interest to eventually varying plant genomes and producing new polyploidy from related or distal plant species. Here, I discuss the potentiality of such an approach to engineer binucleated plant cells as a germ of new plant species to fulfill some environmental applications such as increasing the biodiversity and breeding new species adaptable to harsh environmental stresses and increasing green surfaces to reduce atmospheric pollutions in arid lands with poor vegetation.     

Ulva rigida in the future ocean: potential for carbon capture,bioremediation and biomethane production

Ulva species have been considered as ideal candidates for carbon capture, bioremediation and biofuel production. However, little is known regarding the effects of simultaneous ocean warming, acidification and eutrophication on these capacities. In this study, Ulva rigida was cultivated under two levels of: temperature (14 °C (LT) and 18 °C (HT)); pH (8.10 and 7.70) by controlling pCO₂ (LC, HC respectively); and nutrients (low (LN) – 50 μm N and 2.5 μm P and high (HN) – 1000 μm N and 50 μm P) for 6 weeks. During the first week of cultivation, HT, HC and HN increased biomass by 38.1%, 17.1% and 20.8%, respectively, while the higher temperature led to negative growth in weeks 2, 4 and 6 due to reproductive events. By the end of the cultivation, biomass under HTHCHN was 130.4% higher than the control (LTLCLN), contributing to a higher carbon capture capacity. Although the thalli at HT released nutrients to seawater in weeks 2, 4 and 6, the HTHCHN treatment increased the overall nitrate uptake rate over the cultivation period by 489.0%. The HTHCHN treatment also had an increased biochemical methane potential and methane yield (47.3% and 254.6%, respectively). Our findings demonstrate that the capacities for carbon and nutrient capture, and biomethane production of U. rigida in the future ocean may be enhanced, providing important insight into the interactions between global change and seaweeds.     

Syngas fermentation to biofuel: Evaluation of carbon monoxide mass transfer coefficient (kLa) in different reactor configurations

Lignocellulosic biomass such as agri‐residues, agri‐processing by‐products, and energy crops do not compete with food and feed, and is considered to be the ideal renewable feedstocks for biofuel production. Gasification of biomass produces synthesis gas (syngas), a mixture primarily consisting of CO and H₂. The produced syngas can be converted to ethanol by anaerobic microbial catalysts especially acetogenic bacteria such as various clostridia species.One of the major drawbacks associated with syngas fermentation is the mass transfer limitation of these sparingly soluble gases in the aqueous phase. One way of addressing this issue is the improvement in reactor design to achieve a higher volumetric mass transfer coefficient (k_La). In this study, different reactor configurations such as a column diffuser, a 20‐μm bulb diffuser, gas sparger, gas sparger with mechanical mixing, air‐lift reactor combined with a 20‐μm bulb diffuser, air‐lift reactor combined with a single gas entry point, and a submerged composite hollow fiber membrane (CHFM) module were employed to examine the k_La values. The k_La values reported in this study ranged from 0.4 to 91.08 h^?1. The highest k_La of 91.08 h^?1 was obtained in the air‐lift reactor combined with a 20‐μm bulb diffuser, whereas the reactor with the CHFM showed the lowest k_La of 0.4 h^?1. By considering both the k_La value and the statistical significance of each configuration, the air‐lift reactor combined with a 20‐μm bulb diffuser was found to be the ideal reactor configuration for carbon monoxide mass transfer in an aqueous phase. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

华南热带区不同恢复阶段人工林土壤持水能力研究

选择华南热带区小良试验站中光裸地、桉树林、阔叶混交林和村边次生林4种不同恢复阶段的植被类型,测定不同层次的土壤容重、持水量、孔隙度等参数。结果表明：光裸地土质结实,容重在1.5 g cm-3以上;种植桉树后如果长期人为去除地表枯落物,其地表更为板结,土壤持水能力极差。桉树林改造为阔叶混交林后,0~40 cm土层的容重均低于1.3 g cm-3,土壤总孔隙度为46.1%~51.4%,非毛管孔隙度15.0%~22.7%,土壤持水能力明显优于光裸地和桉树林。混交林土壤0~40 cm层次的最大蓄水量达到1892 t hm-2,比光裸地和桉树林分别多269 t hm-2和418 t hm-2。村边次生林土壤容重最低,表层(0~10 cm)仅1.07 g cm-3,土壤总孔隙度为58%,土壤最大持水量可达538 g kg-1,均明显优于阔叶混交林。光裸地在26年间容重下降了27.7%,但其容重仍较大,阔叶混交林土壤由于系统功能的整体改善,土壤也变得更疏松,土壤持水能力有较大幅度提高,而桉树林土壤长期保持板结状态,土壤持水能力变化不大。建立种类多样、结构复杂的人工林可以显著增强地表水的入渗能力和土壤持水能力。     

Effects of fire disturbance on the soil physical and chemical properties and vegetation of Pinus massoniana forest in south subtropical area

A variety of studies on the impact of fire disturbance on ecosystems has shown that the physical and chemical properties of soil after fire disturbance change notably. Meanwhile, little is known about the effects of different fire intensities on the soil properties and vegetation after fire disturbance, especially in the south subtropical area. In this paper, we analyzed the soil physical and chemical properties, vegetation species and species diversity of fire center, fire edge (which was burned a year ago) and non-burned Pinus massoniana plantation in Gaoyao, Guangdong province, China. The results showed that the soil conductivity, water content, total nitrogen, total potassium, and available potassium content of fire center were significantly higher than those of the non-burned land, and pH was higher than that of fire edge, whereas the available nitrogen, total phosphorus and organic matter content were much lower, which were generally existed in 0–10 cm soil layer and 10–30 cm soil layer. Changes of the soil properties of fire edge were similar with those of fire center, but less significant, and seemed to be more complex. Effects of burning on the vegetation of fire disturbance plots were found to be notable, species number and average height of plants of fire disturbance plots were lower than those of the non-burned plots, a difference of species diversity and uniformity were also shown, and finally, the composition of plant community also changed, e.g., pioneer species such as D. dichotoma, etc., dominated, and drought-resistant plants, heat-resistant plants and positive plants increased after burning.     

Genetic modification in cellulose‐synthase reduces crystallinity and improves biochemical conversion to fermentable sugar

The cellulose synthase (CESA) membrane complex synthesizes microfibrils of cellulose that surround all plant cells. Cellulose is made of sugar (β,1‐4 glucan) and accessing the sugar in cellulose for biofuels is of critical importance to stem the use of fossil fuels and avoid competition with food crops and pristine lands associated with starch‐based biofuel production. The recalcitrance of cellulose to enzymatic conversion to a fermentable form of sugar is related to the degree of hydrogen bonding or crystallization of the glucan chain. Herein, we isolate the first viable low biomass‐crystallinity mutant by screening for altered cell wall structure using X‐ray scattering as well as screening for enzymatic conversion efficiency on a range of cell wall mutants in the model plant Arabidopsis thaliana (L.) Heynh. Through detailed analysis of the kinetics of bioconversion we identified a mutant that met both selection criteria. This mutant is ixr1‐2, which contains a mutation in a highly conserved consensus sequence among the C‐terminal transmembrane regions within CESA3. A 34% lower biomass crystallization index and 151% improvement in the efficiency of conversion from raw biomass to fermentable sugars was measured relative to that of wild type (Col‐0). Recognizing the inherent ambiguities with an insoluble complex substrate like cellulose and how little is still understood regarding the regulation of CESA we propose a general model for how to manipulate CESA enzymes to improve the recalcitrance of cellulose to enzymatic hydrolysis. This study also raises intriguing possibilities as to the functional importance of transmembrane anchoring in CESA complex and microfibril formation.