Carbon Sequestration Change Research Articles

Linking land and lake: Using novel geochemical techniques to understand biological response to environmental change

The exploitation of lakes has led to large-scale contemporary impacts on freshwater systems, largely in response to catchment clearance. Such clearance is causing changes to carbon dynamics in tropical lakes which may have significance for wider carbon budgets, depending on the changes in carbon sequestration and mineralisation driven by changing roles of terrestrial and aquatic carbon in lakes over time. Despite increasing awareness of the pivotal role of carbon source in carbon dynamics, discriminating the source of carbon from a palaeolimnological record is rarely undertaken. Here we use novel geochemical techniques (brGDGTs, n-alkanes, Rock-Eval pyrolysis), paired with traditional analyses (diatoms, pollen), to elucidate changing sources of carbon through time and ecosystem response.Environmental changes at Lake Nyamogusingiri can be divided into three phases: Phase I (CE 1150–1275), a shallow and productive lake, where a diverse terrestrial environment is, initially, the main carbon source, before switching to an aquatic source; Phase II (CE 1275–1900), variable lake levels (generally in decline) with increasing productivity, and carbon is autochthonous in source; Phase III (CE 1900–2007), lake level declines, and the carbon is of a mixed source, though the terrestrially derived carbon is from a less diverse source.The organic geochemical analyses provide a wealth of data regarding the complexity of aquatic response to catchment and with-in lake changes. These data demonstrate that small, tropical lake systems have the potential to bury high quantities of carbon, which has implications for the disruption of local biogeochemical cycles (C, P, N, and Si) both in the past, and the future as human and climate pressures increase.

Experimental herbivore exclusion, shrub introduction, and carbon sequestration in alpine plant communities

BackgroundShrub cover in arctic and alpine ecosystems has increased in recent decades, and is predicted to further increase with climate change. Changes in shrub abundance may alter ecosystem carbon (C) sequestration and storage, with potential positive feedback on global C cycling. Small and large herbivores may reduce shrub expansion and thereby counteract the positive feedback on C cycling, but herbivore pressures have also changed in the alpine-arctic tundra; the increased shrub cover together with changes in herbivore pressure is leading to unpredictable changes in carbon sequestration and storage. In this study we investigate the importance of herbivory and shrub introduction for carbon sequestration in the short term. We measured standing biomass and daytime mid-growing season carbon fluxes in plots in a full factorial design where we excluded small and large mammalian herbivores and introduced Salix by planting Salix transplants. We used three study sites: one Empetrum-dominated heath, one herb- and cryptogam-dominated meadow, and one Salix-dominated shrub community in the low-alpine zone of the Dovre Mountains, Central Norway.ResultsAfter 2 years, significant treatment effects were recorded in the heath community, but not in the meadow and shrub communities. In the heath community cessation of herbivory increased standing biomass due to increased biomass of dwarf shrubs. Cessation of herbivory also reduced biomass of bryophytes and ecosystem respiration (ER). Except for an increase in biomass of deciduous shrubs caused by the Salix introduction, the only effect of Salix introduction was an increase in biomass of graminoids in the heath.ConclusionsOur short-term study demonstrated that herbivore exclusion had small but still significant effects on heath vegetation, whereas such effects were not apparent in the herb-and cryptogam-dominated meadow and the Salix-dominated shrub community. Following the treatments over more years is needed to estimate the long-term effects on community structure and the consequences for C sequestration in the three plant communities. Such data are important for predicting the impact of shrub expansion on C budgets from alpine regions.

A Summary of the Impact of Land Degradation on Soil Carbon Sequestration

Soil carbon pools have a great impact on global climate change, and land degradation caused by natural conditions or human activities is one of the important causes of soil carbon sequestration changes. In order to explore the impact of different types of land degradation on soil carbon sequestration and its mechanisms, this paper reviews the effects of different types of land degradation on soil carbon sequestration, such as desertification, soil erosion, soil salinization, nutrient loss and soil impoverishment. It is pointed out that various types of land degradation will increase the rate of CO2 release from soil to the atmosphere to varying degrees, which will increase the function of soil carbon source and weaken the function of carbon sink. However, the impact of land degradation on soil carbon stocks is likely to be reversed. In the future, the dynamic changes of soil carbon sequestration and deep soil carbon pools in different types of land degradation processes should be strengthened in order to further study the effects of soil carbon cycling in land degradation. And lay a foundation for enhancing the function of soil carbon sources.

Simulating carbon sequestration using cellular automata and land use assessment for Karaj, Iran

Abstract. Carbon sequestration has been proposed as a means of slowing the atmospheric and marine accumulation of greenhouse gases. This study used observed and simulated land use/cover changes to investigate and predict carbon sequestration rates in the city of Karaj. Karaj, a metropolis of Iran, has undergone rapid population expansion and associated changes in recent years, and these changes make it suitable for use as a case study for rapidly expanding urban areas. In particular, high quality agricultural space, green space and gardens have rapidly transformed into industrial, residential and urban service areas. Five classes of land use/cover (residential, agricultural, rangeland, forest and barren areas) were considered in the study; vegetation and soil samples were taken from 20 randomly selected locations. The level of carbon sequestration was determined for the vegetation samples by calculating the amount of organic carbon present using the dry plant weight method, and for soil samples by using the method of Walkley and Black. For each area class, average values of carbon sequestration in vegetation and soil samples were calculated to give a carbon sequestration index. A cellular automata approach was used to simulate changes in the classes. Finally, the carbon sequestration indices were combined with simulation results to calculate changes in carbon sequestration for each class. It is predicted that, in the 15 year period from 2014 to 2029, much agricultural land will be transformed into residential land, resulting in a severe reduction in the level of carbon sequestration. Results from this study indicate that expansion of forest areas in urban counties would be an effective means of increasing the levels of carbon sequestration. Finally, future opportunities to include carbon sequestration into the simulation of land use/cover changes are outlined.

Effects of management regimes on carbon sequestration under the Natural Forest Protection Program in northeast China

Carbon sinks constitute an important element within the complex phenomenon of global climate change, and forest ecosystems are important global carbon sinks. The Natural Forest Protection Program (NFPP) is an ecological program in China that was established after catastrophic flooding in the country in 1998. The goals of the NFPP are to curb the deterioration of the ecological environment, strengthen the protection and restoration of habitat to increase biodiversity, and rehabilitate natural forests to support sustainable development in forest regions. This study looked at changes in carbon sequestration in a forested area of northeast China after the inception of the NFPP. The program divides China’s natural forests into three classes—commercial and two types of noneconomic forests—that are subject to management regimes prescribing varying levels of timber harvest, afforestation, and reforestation. During the 18-year period from 1998 to 2015, the total amount of carbon sequestration increased at an average annual rate of 0.04 MT C. This trend reflects a transformation of forest management practices after implementation of the NFPP that resulted in prohibited and/or restricted logging and tighter regulation of allowable harvest levels for specific areas. In documenting this trend, guidelines for more effective implementation of forestry programs such as the NFPP in other countries in the future are also suggested.

The potential and cost of increasing forest carbon sequestration in Sweden

This paper examines the potential and the cost of promoting forest carbon sequestration through a tax/subsidy to land owners for reducing/increasing carbon storage in their forests. We use a partial equilibrium model based on intertemporal optimization to estimate the impacts of carbon price (the tax/subsidy rate) on timber harvest volume and price in different time periods and on the change of forest carbon stock over time. The results show that a higher carbon price would lead to higher forest carbon stocks. The tax/subsidy induced annual net carbon sequestration is declining over time. The net carbon sequestration during 2015–2050 would increase by 30.2 to 218.3 million tonnes of CO2, when carbon price increases from 170SEK to 1428SEK per tonne of CO2. The associated cost, in terms of reduced total benefits of timber and other non-timber goods, ranges from 80SEK to 105.8SEK per tonne of CO2. The change in carbon sequestration (as compared with the baseline case) beyond 2050 is small when carbon price is 680SEK per tonne of CO2 or lower. With a carbon price of 1428SEK per tonne of CO2, carbon sequestration will increase by 70 million tonnes of CO2 from the baseline level during 2050-2070, and by 64 million tonnes during 2070–2170.

Assessment of spatio-temporal changes in terrestrial carbon sequestration due to Kochi metro rail project in India

Major infrastructure projects can cause sizeable reduction in the urban tree cover thereby affecting terrestrial carbon sequestration potential of cities. This study investigated the spatio-temporal changes occurred in terrestrial carbon sequestration due to the metro rail project at Kochi city in India during the years 2013 to 2015. Normalized Difference Vegetation Index (NDVI) estimated from IRS-P6 LISS IV satellite sensor data was used to detect the tree cover change and for the quantification of carbon stock. An urban carbon storage equation was used to estimate the carbon content from NDVI values. Stock difference approach was used to estimate the change in carbon sequestration due to the construction of metro rail. Results indicated reduction of 14.51ha of tree cover area within a distance of 60m from the center-line of metro rail during the study period. Study found that 2316 tCO2e was emitted as a result of cutting urban trees for the metro rail. Such an emission was overlooked while estimating the emission reduction due to the promotion of public transport. This study points to the need for estimating the impacts of major urban infrastructure projects to the global climate in addition to assessing their mostly localized environmental impacts.

Changes in Carbon Cycling during Development of Successional Agroforestry

Successional agroforestry systems (SAFS) mimic the structure of natural forests while providing economical outputs. This study clarifies how carbon cycling and carbon sequestration change during successional development of SAFS. In Brazil, three successional stages of SAFS, 6, 12, and 34 years old, were compared in terms of carbon balance. Aboveground biomass, fruit harvest, litterfall, soil respiration, and soil organic carbon were measured for two years and analyzed. Carbon sequestration expressed by net primary productivity increased with age of SAFS from 9.8 Mg·C·ha−1·year−1 in 6-year-old system to 13.5 Mg·C·ha−1·year−1 in 34-year-old system. Accumulation of plant biomass and increased internal carbon cycling in SAFS led to an intensive sequestration of carbon. SAFS can be a sustainable way of agricultural production on vulnerable tropical soils.

Impacts of land use change due to biofuel crops on climate regulation services: Five case studies in Malawi, Mozambique and Swaziland

Understanding changes in carbon sequestration due to land conversion is key for elucidating the true potential of biofuel landscapes to provide climate regulation ecosystem services. In this study, we focus on the two most promoted biofuel crops in southern Africa, Jatropha and sugarcane, to analyse the land use change effects and associated carbon impacts of growing biofuel crops in five study sites in Mozambique, Malawi and Swaziland. We found that, considering a 20-year cycle, carbon stocks in aboveground biomass are higher for sugarcane than for Jatropha. However, as soil organic carbon (SOC) is generally the main carbon pool, total carbon stocks (considering biomass and soil) will highly depend on SOC. Our results show that, in our study sites, sugarcane replaced land uses with low carbon stocks (low-density forest and agriculture), and as a result carbon gains occurred due to land use change. In the Jatropha projects, carbon gains are observed in the smallholder scheme as agricultural land was converted to Jatropha, but carbon debts occurred in the Jatropha plantation as high-density forest was cleared to grow this feedstock. Finally we show that, if a plantation of sugarcane or Jatropha is envisioned to be located in the studied regions, more forested land could potentially be converted into sugarcane (30–44% of forest) than into Jatropha (24–32%), without creating carbon debts due to land conversion. To our knowledge, this is the first comparative study of the carbon impacts of land use change of the main biofuel crops in southern Africa.

Improved models for estimating temporal changes in carbon sequestration in above-ground biomass of mixed-species environmental plantings

Plantings of mixed native species (termed ‘environmental plantings’) are increasingly being established for carbon sequestration whilst providing additional environmental benefits such as biodiversity and water quality. In Australia, they are currently one of the most common forms of reforestation. Investment in establishing and maintaining such plantings relies on having a cost-effective modelling approach to providing unbiased estimates of biomass production and carbon sequestration rates. In Australia, the Full Carbon Accounting Model (FullCAM) is used for both national greenhouse gas accounting and project-scale sequestration activities. Prior to undertaking the work presented here, the FullCAM tree growth curve was not calibrated specifically for environmental plantings and generally under-estimated their biomass. Here we collected and analysed above-ground biomass data from 605 mixed-species environmental plantings, and tested the effects of several planting characteristics on growth rates. Plantings were then categorised based on significant differences in growth rates. Growth of plantings differed between temperate and tropical regions. Tropical plantings were relatively uniform in terms of planting methods and their growth was largely related to stand age, consistent with the un-calibrated growth curve. However, in temperate regions where plantings were more variable, key factors influencing growth were planting width, stand density and species-mix (proportion of individuals that were trees). These categories provided the basis for FullCAM calibration. Although the overall model efficiency was only 39–46%, there was nonetheless no significant bias when the model was applied to the various planting categories. Thus, modelled estimates of biomass accumulation will be reliable on average, but estimates at any particular location will be uncertain, with either under- or over-prediction possible. When compared with the un-calibrated yield curves, predictions using the new calibrations show that early growth is likely to be more rapid and total above-ground biomass may be higher for many plantings at maturity. This study has considerably improved understanding of the patterns of growth in different types of environmental plantings, and in modelling biomass accumulation in young (<25years old) plantings. However, significant challenges remain to understand longer-term stand dynamics, particularly with temporal changes in stand density and species composition.

Short- and long-term effects of nutrient enrichment on microbial exoenzyme activity in mangrove peat

Mangroves receive increasing quantities of nutrients as a result of coastal development, which could lead to significant changes in carbon sequestration and soil subsidence. We hypothesised that mangrove-produced tannins induce a nitrogen (N) limitation on microbial decomposition even when plant growth is limited by phosphorus (P). As a result, increased N influx would lead to a net loss of sequestered carbon negating the ability to compensate for sea level rise in P-limited mangroves. To examine this, we quantified the short- and long-term effects of N and P enrichment on microbial biomass and decomposition-related enzyme activities in a Rhizophora mangle-dominated mangrove, which had been subjected to fertilisation treatments for a period of fifteen years. We compared microbial biomass, elemental stoichiometry and potential enzyme activity in dwarf and fringe-type R. mangle-dominated sites, where primary production is limited by P or N depending on the proximity to open water. Even in P-limited mangroves, microbial activity was N-limited as indicated by stoichiometry and an increase in enzymic activity upon N amendment. Nevertheless, microbial biomass increased upon field additions of P, indicating that the carbon supply played even a larger role. Furthermore, we found that P amendment suppressed phenol oxidase activity, while N amendment did not. The possible differential nutrient limitations of microbial decomposers versus primary producers implies that the direction of the effect of eutrophication on carbon sequestration is nutrient-specific. In addition, this study shows that phenol oxidase activities in this system decrease through P, possibly strengthening the enzymic latch effect of mangrove tannins. Furthermore, it is argued that the often used division between N-harvesting, P-harvesting, and carbon-harvesting exoenzymes needs to be reconsidered.

Estimating temporal changes in carbon sequestration in plantings of mallee eucalypts: Modelling improvements

Establishment of mallee eucalypt plantings on cleared agricultural land is currently the predominant method of reforestation for carbon sequestration in Australia. Investment in establishing and maintaining such plantings relies on having a cost-effective approach for providing un-biased estimates of yield in biomass and carbon sequestration. The Australian Government’s forest carbon accounting model (FullCAM) had not previously been calibrated for mallee eucalypt plantings and, in many circumstances, substantially under-estimated of biomass for these plantings. Our objective was to improve model applicability and reliability of estimates of carbon sequestration. To achieve this, we first collected and analysed above-ground biomass data from 257 mallee eucalypt plantings (or 744 observations, when including the multiple measurements made at some planting sites) to determine the key factors influencing growth. Plantings were categorised according to species, planting configuration (block or belt plantings) and stand density. Each category of planting had significantly different rates of growth, with the rates of sequestration of above-ground biomass carbon being relatively high when established in densely-stocked, two-row belts. These categories of plantings then provided the basis for calibration (estimation of appropriate modifiers) of FullCAM growth curves. Overall model efficiency was 63%, and there was no apparent bias when the model was applied to the various planting categories. Thus, modelled estimates of biomass accumulation will be reliable on average but at any particular location will be highly uncertain, with either substantial under- or over-prediction possible. For some categories of mallee eucalypt plantings, and for plantings with access to ground-water or established in non-productive soils, there were insufficient observations to provide confidence in new calibrations specific for these circumstances. Moreover, application of the calibrations provided here are applicable for prediction of sequestration of biomass carbon of relatively young (<15-year-old) stands, with more data needed for prediction of longer-term rates of growth.

Analysis of Ecosystem Carbon Sequestration Change in Guangxi, China from 2000 to 2010 Based on Remote Sensing Data

The global change and terrestrial ecosystem (GCTE) is an important research issue in research of global climate change , and terrestrial Ecosystem carbon sequestration is one of the main content of the study. In this paper, ecosystem carbon sequestration capacity calculation and trend analysis of Guangxi Province were made based on the data of remote sensing inversion, for the study of the main ecosystem carbon fixed quantity of spatial distribution and change of Guangxi province over the past 10 years (2000-2010). The results indicated that the ecosystem carbon fixed amount of Guangxi region present high on all sides and low in the center , the spatial distribution of carbon is mainly depends on the spatial distribution of vegetation ecosystem, as the areas of artificial vegetation carbon stocks are generally lower than that of carbon stocks in mountain areas. The amount of carbon fixed showed a general trend of increase from 2000 to 2010.

An enhanced method for using the IPCC approach to estimate soil organic carbon storage potential on U.S. agricultural soils

The Intergovernmental Panel on Climate Change (IPCC) provides a method to estimate soil organic carbon (SOC) stock changes relative to the SOC stock under native vegetation. This manuscript modifies the IPCC approach to use the ending SOC stock from the previous inventory as the SOC stock that is changed by land use and management activities during the next inventory and to track the crop rotation and tillage intensity through three inventories. The approach allows annual rates of change of carbon sequestration from different historic land uses and management to be estimated explicitly for each assessment point based on the effect of previous land use and management. The model generates 3524 unique annual SOC sequestration rates that vary by land use and management history on U.S. agricultural land based on the 30 SOC stock reference values provided by IPCC documentation. An average of 0.33MgCha−1yr−1 is stored when cropland that was conventionally tilled in two previous inventories is set-aside in the third inventory, but only 0.14MgCha−1yr−1 when it is conventionally tilled in the first inventory and no-till in the second inventory before it is set aside. Incorporating a winter cover on cropland that was conventionally tilled in the first inventory and no-till in the second and third inventories is estimated to store 0.49MgCha−1yr−1, but could store 0.81MgCha−1yr−1 if it was conventionally tilled in the first two inventories and under no-till in the final inventory. Cropland under conventional tillage in the first two inventories and no-till the final inventory could store an average of 0.34MgCha−1yr−1, but cropland under conventional tillage in the first, reduced tillage in the second, and no-till in the third inventory is estimated to store 0.19MgCha−1yr−1. The detailed annual rates of SOC stock change estimated using the approach is useful for economic or other analyses and for policymakers.

Can we produce carbon and climate neutral forest bioenergy?

AbstractHarvesting branches, stumps and unmercantable tops, in addition to stem wood, decreases the carbon input to the soil and consequently reduces the forest carbon stock. We examine the changes in the forest carbon cycle that would compensate for this carbon loss over a rotation period and lead to carbon neutral forest residue bioenergy systems. In addition, we analyse the potential climate impact of these carbon neutral systems. In a boreal forest, the carbon loss was compensated for with a 10% increase in tree growth or a postponing of final felling for 20 years from 90 to 110 years in one forest rotation period. However, these changes in carbon sequestration did not prevent soil carbon loss. To recover soil carbon stock, a 38% increase in tree growth or a 21% decrease in the decomposition rate of the remaining organic matter was needed. All the forest residue bioenergy scenarios studied had a warming impact on climate for at least 62 years. Nevertheless, the increases in the carbon sequestration from forest growth or reduction in the decomposition rate of the remaining organic matter resulted in a 50% smaller warming impact of forest bioenergy use or even a cooling climate impact in the long term. The study shows that carbon neutral forest residue bioenergy systems have warming climate impacts. Minimization of the forest carbon loss improves the climate impact of forest bioenergy.

Wood chemistry and density: An analog for response to the change of carbon sequestration in mangroves

This study aimed to resolve the variations of physical and chemical properties of wood records measured in different mangroves with their annual carbon sequestration. The methods of investigation used were to examine growth rate by monitoring breast height diameter, wood chemistry and density, FTIR spectroscopy and thermogravimetry. Carbon sequestration rate showing an increase with density varied between 0.088 and 0.171μgCkg−1AGBs−1, and Avicennia marina showed the maximum value and Bruguiera gymnorrhiza, the minimum. The changes in FTIR bands at 4000–2500cm−1 and 1700–800cm−1 were correlated to the variations in cellulose in mangrove woods and lignin to cellulose ratio ranged between 0.21 and 1.75. Thermal analyses of mangrove wood suggested that the fuel value index (985–3922) exhibited an increase with the decrease in maximum decomposition temperature and density. The seasonal variation of temperature and CO2 were likely to affect chemical properties through changes in wood density.

Detection and attribution of global change and disturbance impacts on a tower-observed ecosystem carbon budget: a critical appraisal

Observations worldwide are providing an increasing amount of atmosphere–ecosystem flux data. Thus, the establishment of a data mining methodology to detect significant trends and attribute changes to specific factors is important. This study examined the possibility of detecting significant trends in observed data at a test site with one of the longest records of flux measurements (Takayama, Japan). Statistical tests using non-parametric methods showed a ‘likely’ trend (i.e., detected at 66–90% confidence level) of increasing carbon sequestration. To investigate the change in carbon sequestration in relation to biological and environmental factors (ambient CO2, temperature, radiation, precipitation and disturbance), mechanistic and numerical methods were applied. A process-based model was used for the mechanistic attribution of change, and an optimal fingerprinting method in combination with model-based sensitivity simulations was used for numerical attribution. At the study site, local disturbances appeared to exert an impact on the observed carbon sequestration, whereas climatic factors made moderate contributions. These results indicate the feasibility of detection and attribution using current flux measurement data, although more evidence is needed to confirm global coherence.

Recent height and diameter growth variation in Scots pine (Pinus sylvestris L.) along the Arctic margin: the importance of growing season versus non-growing season climate factors

Background: High-latitude forests are controlled by climate and as temperature increases, a northward extension in distribution and more vigorous tree growth are expected. The replacement of tundra by forest involves changes in carbon sequestration, land–atmosphere energy balance and ecosystems. The understanding of climate-related height and diameter growth patterns across geographical regions is therefore important. Aim: To analyse recent within- and between-region variations in climate–growth relationships for Scots pine at the forest–tundra ecotone (northern Norway, Kola Peninsula). Methods: Six pine (Pinus sylvestris) woodland sites, representing different climate regions along the forest–tundra zone, were sampled for annual height growth (saplings) and diameter growth (adult trees) and the analyses were related to local climate data. Results: Height growth was strongly similar among all sites and climate regions, but not diameter growth. Although summer temperature was the most important factor, non-growing season climate showed significant importance for both diameter and height growth across regions. Conclusions: The results highlight the importance of factors that are often overlooked, specifically, non-growing season factors for tree growth at high latitudes, and the role of short-term climate variation. Future climate scenarios predict moister and milder winters for large areas of high-latitude regions. Thus, detailed analyses of region-specific climate–growth relations that focus on growing season vs. non-growing season effects are essential in the evaluation of future forest cover response to climate change.

Preliminary Studies on Carbon Sequestration Changes of Wood Materials in Manufacturing Process

In this paper, we initially inspected the carbon storage changes of wood materials in manufacturing process combined energy consumption and material loss of wood materials in manufacturing process, analysed carbon sequestration potential of wood materials, and demonstrated the role of using wood in reducing CO2 emission and mitigating climate warming.

Impact of Climate Change on Forest Fire Severity and Consequences for Carbon Stocks in Boreal Forest Stands of Quebec, Canada: a Synthesis

The global boreal forests comprise large stocks of organic carbon that vary with climate and fire regimes. Global warming is likely to influence several aspects of fire and cause shifts in carbon sequestration patterns. Fire severity or forest floor depth of burn is one important aspect that influences both carbon emission during combustion as well as post-fire ecosystem regeneration. Numerous publications on projections of future area burned exist, whereas scenarios on twenty-first century fire severity are more scarce, and the stand-typical response to severe fire weather is rarely taken into account. This paper aims to synthesize knowledge on boreal forest carbon stocks in relation to changes in fire severity for Quebec, Canada. Besides warming, this region may be subjected to an important increase in future precipitation. Future fire severity and area burned may well increase as fire weather will be drier, especially near the end of the twenty-first century. Moreover, the fire season peak may shift towards the late summer. Intense burning will favour tree cover development while the forest floor carbon stock may become less important. As a result, total Quebec boreal carbon sequestration may diminish. The development of dynamic vegetation models may improve scenarios on twenty-first century changes in carbon sequestration driven by climate change and fire severity and frequency effects.