ALBERT

Description: Background Mangrove forests have gained recognition for their potential role in climate change mitigation due to carbon sequestration in live trees, and carbon storage in the sediments trapped by mangrove tree roots and pneumatophores. Africa hosts about 19% of the world’s mangroves, yet relatively few studies have examined the carbon stocks of African mangroves. The available studies report considerable differences among sites and amongst the different pools of carbon stocks. None considered the effects of seaward distance. We present details of AGC and SOC carbon stocks for Lindi in Tanzania, and focus on how these values differ with increasing seaward distance and, how our results compare to those reported elsewhere across Africa. Results AGC ranged between 11 and 55 Mg C ha−1, but was not significantly affected by seaward distance. SOC for 0–1 m depth ranged from 154 to 484, with a mean of 302 Mg C ha−1. SOC was significantly negatively correlated with seaward distance. Mangrove type (estuarine/oceanic), soil erosion, soil depth may explain these differences We note important methodological differences in previous studies on carbon stocks in mangroves in Africa. Conclusion This study indicates that seaward distance has an important effect on SOC stocks in the Lindi region of Tanzania. SOC should be fully incorporated into national climate change mitigation policies. Studies should report seaward distance and to describe the type of mangrove stand to make results easily comparable across sites and to assess the true value of Blue Carbon in Africa. We recommend focusing on trees 〉 10 cm diameter for AGC, and sampling soils to at least 1 m depth for SOC, which would provide a more complete assessment of the potentially considerable mangrove carbon store.

Description: Background Existing research provides estimates of the biophysical potential for increasing soil organic carbon (SOC) stock, however additional research is needed to enhance our understanding of the economic potential for agricultural soils to offset or help reduce CO2 emissions. This study derives the marginal cost to increase SOC sequestration by combining SOC sequestration potential estimates developed using the Intergovernmental Panel on Climate Change (IPCC) factors with an existing payment scheme that was designed to increase no-till (NT) adoption on U.S. cropland. The marginal costs of increasing SOC is a function of the amount of SOC that could be increased through NT and the expected cost to landowners of changing management to use NT. Results The variability in SOC sequestration rates due to different land-use, management histories, climate, and soils, combined with the 48 unique payment rates to adopt NT, yield over 5,000 unique marginal cost values for increasing SOC sequestration. Nearly 95 percent of the biophysical potential SOC sequestration increase on U.S. cropland (2802 Tg CO2 from 140.1 Tg CO2 year−1 for 20 years) could be captured for less than $100 Mg−1 CO2. An estimated 64 to 93 percent of the biophysical potential could be captured for less than the low and high estimated costs to capture CO2 for geologic storage of $36.36 to $86.06 Mg−1 CO2, respectively. Conclusions Decreasing tillage intensity through adoption of no-till agriculture offers a cost-effective way to offset a portion of increasing global CO2 emissions. This research demonstrates that increasing SOC stocks through NT adoption can offset CO2 emissions at a lower cost than some other options for preventing CO2 from entering the atmosphere.

Description: Background Quantifying CO2 emissions from cities is of great importance because cities contribute more than 70% of the global total CO2 emissions. As the largest urbanized megalopolis region in northern China, the Beijing-Tianjin-Hebei (Jing-Jin-Ji, JJJ) region (population: 112.7 million) is under considerable pressure to reduce carbon emissions. Despite the several emission inventories covering the JJJ region, a comprehensive evaluation of the CO2 emissions at the prefectural city scale in JJJ is still limited, and this information is crucial to implementing mitigation strategies. Results Here, we collected and analyzed 8 published emission inventories to assess the emissions and uncertainty at the JJJ city level. The results showed that a large discrepancy existed in the JJJ emissions among downscaled country-level emission inventories, with total emissions ranging from 657 to 1132 Mt CO2 (or 849 ± 214 for mean ± standard deviation (SD)) in 2012, while emission estimates based on provincial-level data estimated emissions to be 1038 and 1056 Mt. Compared to the mean emissions of city-data-based inventories (989 Mt), provincial-data-based inventories were 6% higher, and national-data-based inventories were 14% lower. Emissions from national-data-based inventories were 53–75% lower in the high-emitting industrial cities of Tangshan and Handan, while they were 47–160% higher in Beijing and Tianjin than those from city-data-based inventories. Spatially, the emissions pattern was consistent with the distribution of urban areas, and urban emissions in Beijing contributed 50–70% of the total emissions. Higher emissions from Beijing and Tianjin resulted in lower estimates of prefectural cities in Hebei for some national inventories. Conclusions National-level data-based emission inventories produce large differences in JJJ prefectural city-level emission estimates. The city-level statistics data-based inventories produced more consistent estimates. The consistent spatial distribution patterns recognized by these inventories (such as high emissions in southern Beijing, central Tianjin and Tangshan) potentially indicate areas with robust emission estimates. This result could be useful in the efficient deployment of monitoring instruments, and if proven by such measurements, it will increase our confidence in inventories and provide support for policy makers trying to reduce emissions in key regions.

Description: Background The fast-growing introduced mangrove Sonneratia apetala is widely used for mangrove afforestation and reforestation in China. Some studies suggested that this exotic species outperforms native species in terms of carbon sequestration potential. This study tested the hypothesis that multi-species mangrove plantations might have higher carbon sequestration potential than S. apetala monocultures. Results Our field measurements at Hanjiang River Estuary (Guangdong province, China) showed that the carbon stock (46.0 ± 3.0 Mg/ha) in S. apetala plantations where the native Kandelia obovata formed an understory shrub layer was slightly higher than that in S. apetala monocultures (36.6 ± 1.3 Mg/ha). Moreover, the carbon stock in monospecific K. obovata stands (106.6 ± 1.4 Mg/ha) was much larger than that of S. apetala monocultures. Conclusions Our results show that K. obovata monocultures may have a higher carbon accumulation rate than S. apetala monocultures. Planting K. obovata seedlings in existing S. apetala plantations may enhance the carbon sink associated with these plantations.

Description: Background We determine the occurrence of self-citations among 36 Chilean ecologists with the highest h index values recorded in Web of Science. Because the practice of self-citation is perceived as negative by inflating a given researcher’s impact factor, we evaluate if those ecologists (five of them having been awarded the National Prize in Natural Sciences) tend unduly to self-citation, or alternately, receive citations from others ostensibly because their peers recognize their theoretical and empirical output. Methods and findings We use a recently proposed self-citation estimate easily calculated from h index values recorded in the restricted-access Web of Science (Wos) database and the open-access Google Scholar’s (GS) Researcher Profiles and compare these metrics. Conclusions The Chilean ecologists showed low self-citation values, independently of their status as National Prize awardees. Their publications were highly cited by unrelated peers, likely on account of their novelty or quality. Among middle-aged (50–60 year) and young (

Description: Background Water-use efficiency (WUE) represents the coupling of forest carbon and water. Little is known about the responses of WUE to thinning at multiple spatial scales. The objective of this research was to use field measurements to understand short-term effects of two thinning treatments (T1: 4500 stems ha−1; and T2: 1100 stems ha−1) and the control (NT: 27,000 stems ha−1) on WUE at the three spatial scales (leaf level: the ratio of leaf photosynthesis to leaf transpiration; tree-level: tree growth to tree transpiration; and stand level: net primary production (NPP) to stand transpiration) and intrinsic WUEi (the ratio of leaf photosynthesis to stomatal conductance at leaf-level; and NPP to canopy conductance at stand-level) in a 16-year old natural lodgepole pine forest. Leaf-level measurements were conducted in 2017, while tree- and stand-level measurements were conducted in both 2016 (the normal precipitation year) and 2017 (the drought year). Results The thinning treatments did not significantly affect the tree- and stand-level WUE in the normal year of 2016. However, the thinning significantly affected WUE in the drought year of 2017: T2 exhibited significantly higher tree-level WUE (0.49 mm2 kg−1) than NT (0.08 mm2 kg−1), and compared to NT, the stand-level WUE values in the thinned stands (T1 and T2) were significantly higher, with means of 0.31, 0.56 and 0.70 kg m−3, respectively. However, the leaf-level and stand-level WUEi in the thinned stands in the drought year were significantly lower than those in the unthinned stands. No significant differences in the leaf-level WUE were found among the treatments in 2017. In addition, the thinning did not significantly change the WUE-VPD relationships at any studied spatial scale. Conclusions The thinning treatments did not cause significant changes in all studied WUE metrics in a normal year. However, their effects were significantly promoted under the drought conditions probably due to the decrease in soil water availability, demonstrating that thinning can improve WUE and consequently support forests to cope with the drought effects. The inconsistent results on the effects of the thinning on forest carbon and water coupling at the spatial scales and the lack of the consistent WUE metrics constraint across-scale comparison and transferring of WUE.

Description: Background Organic viticulture can generate a range of ecosystem services including supporting biodiversity, reducing the use of conventional pesticides and fertilizers, and mitigating greenhouse gas emissions through long-term carbon (C) storage. Here we focused on aboveground C storage rates and accumulation using a one-year increment analysis applied across different winegrape varietals and different-aged vineyard blocks. This produced a chronosequence of C storage rates over what is roughly the productive lifespan of most vines (aged 2–30 years). To our knowledge, this study provides the first estimate of C storage rates in the woody biomass of vines. Additionally, we assessed C storage in wildland buffers and adjacent oak-dominated habitats over a 9-year period. Results Carbon storage averaged 6.5 Mg/Ha in vines. We found the average annual increase in woody C storage was 43% by mass. Variation correlated most strongly with vine age, where the younger the vine, the greater the relative increase in annual C. Decreases in C increment rates with vine age were more than offset by the greater overall biomass of older vines, such that C on the landscape continued to increase over the life of the vines at 18.5% per year on average. Varietal did not significantly affect storage rates or total C stored. Carbon storage averaged 81.7 Mg/Ha in native perennial buffer vegetation; we found an 11% increase in mass over 9 years for oak woodlands and savannas. Conclusions Despite a decrease in the annual rate of C accumulation as vines age, we found a net increase in aboveground C in the woody biomass of vines. The results indicate the positive role that older vines play in on-farm (vineyard) C and overall aboveground accumulation rates. Additionally, we found that the conservation of native perennial vegetation as vineyard buffers and edge habitats contributes substantially to overall C stores. We recommend that future research consider longer time horizons for increment analysis, as this should improve the precision of C accumulation rate estimates, including in belowground (i.e., soil) reservoirs.

Description: Bombus terrestris is a European bumblebee extensively commercialized worldwide for crop pollination. In Chile, this species was introduced in 1997 and after confinement escape, it has spread and established in several localities of central-southern Chile and in the Argentine Patagonia. The South American carpenter bee Xylocopa augusti, in turn, has been recently reported in central Chile, and as B. terrestris, this species has become increasingly common, often found in sympatry with B. terrestris in some localities. While intestinal parasites such as the flagellate trypanosome Crithidia bombi, the microsporidium Nosema bombi, and the neogregarine protozoan Apicystis bombi, show high levels of specialization on the Bombus genus, parasites often increase their host range, especially after invading novel habitats, hence creating new infection disease scenarios. In this work, we used molecular techniques to detect the presence of the intestinal pathogens of B. terrestris in coexisting X. augusti from different localities in the Metropolitan Region of Chile. Our results revealed the presence of the three pathogens in B. terrestris only, with population prevalence broadly similar to that reported in other studies. The carpenter bee X. augusti did not show evidence of any of the three parasites examined, indicating that this invader species is not recipient of any of the parasite species present in B. terrestris.

Description: Background Cities contribute more than 70% of global anthropogenic carbon dioxide (CO2) emissions and are leading the effort to reduce greenhouse gas (GHG) emissions through sustainable planning and development. However, urban greenhouse gas mitigation often relies on self-reported emissions estimates that may be incomplete and unverifiable via atmospheric monitoring of GHGs. We present the Hestia Scope 1 fossil fuel CO2 (FFCO2) emissions for the city of Baltimore, Maryland—a gridded annual and hourly emissions data product for 2010 through 2015 (Hestia-Baltimore v1.6). We also compare the Hestia-Baltimore emissions to overlapping Scope 1 FFCO2 emissions in Baltimore’s self-reported inventory for 2014. Results The Hestia-Baltimore emissions in 2014 totaled 1487.3 kt C (95% confidence interval of 1158.9–1944.9 kt C), with the largest emissions coming from onroad (34.2% of total city emissions), commercial (19.9%), residential (19.0%), and industrial (11.8%) sectors. Scope 1 electricity production and marine shipping were each generally less than 10% of the city’s total emissions. Baltimore’s self-reported Scope 1 FFCO2 emissions included onroad, natural gas consumption in buildings, and some electricity generating facilities within city limits. The self-reported Scope 1 FFCO2 total of 1182.6 kt C was similar to the sum of matching emission sectors and fuels in Hestia-Baltimore v1.6. However, 20.5% of Hestia-Baltimore’s emissions were in sectors and fuels that were not included in the self-reported inventory. Petroleum use in buildings were omitted and all Scope 1 emissions from industrial point sources, marine shipping, nonroad vehicles, rail, and aircraft were categorically excluded. Conclusions The omission of petroleum combustion in buildings and categorical exclusions of several sectors resulted in an underestimate of total Scope 1 FFCO2 emissions in Baltimore’s self-reported inventory. Accurate Scope 1 FFCO2 emissions, along with Scope 2 and 3 emissions, are needed to inform effective urban policymaking for system-wide GHG mitigation. We emphasize the need for comprehensive Scope 1 emissions estimates for emissions verification and measuring progress towards Scope 1 GHG mitigation goals using atmospheric monitoring.

Description: Background The potential contributions from forest-based greenhouse gas (GHG) mitigation actions need to be quantified to develop pathways towards net negative emissions. Here we present results from a comparative analysis that examined mitigation options for British Columbia’s forest sector. Mitigation scenarios were evaluated using a systems perspective that takes into account the changes in emissions and removals in forest ecosystems, in harvested wood product (HWP) carbon stocks, and in other sectors where wood products substitute for emission-intensive materials and fossil fuels. All mitigation activities were assessed relative to a forward-looking ‘business as usual’ baseline for three implementation levels. In addition to quantifying net GHG emission reductions, we assessed economic, and socio-economic impacts as well as other environmental indicators relating to forest species, age class, deadwood availability and future timber supply. We further considered risks of reversal for land-based scenarios, by assessing impacts of increasing future wildfires on stands that were not harvested. Results Our spatially explicit analyses of forest sector mitigation options demonstrated a cost-effective portfolio of regionally differentiated scenarios that directed more of the harvested wood to longer-lived wood products, stopped burning of harvest residues and instead produced bioenergy to displace fossil fuel burning, and reduced harvest levels in regions with low disturbance rates. Domestically, net GHG emissions were reduced by an average of -9 MtCO2e year−1 over 2020–2050 for a portfolio of mitigation activities at a default implementation level, with about 85% of the GHG emission reductions achieved below a cost of $50/tCO2e. Normalizing the net GHG reduction by changes in harvested wood levels permitted comparisons of the scenarios with different ambition levels, and showed that a 1 MtCO2 increase in cumulative harvested stemwood results in a 1 MtCO2e reduction in cumulative emissions, relative to the baseline, for the Higher Recovery scenario in 2070. Conclusions The analyses conducted in this study contribute to the global understanding of forest sector mitigation options by providing an integrated framework to synthesize the methods, assumptions, datasets and models needed to quantify mitigation activities using a systems approach. An understanding of economically feasible and socio-economically attractive mitigation scenarios along with trade offs for environmental indicators relating to species composition and age, helps decision makers with long-term planning for land sector contributions to GHG emission reduction efforts, and provides valuable information for stakeholder consultations.