Field Abandonment Research Articles

Cropping Practices and Effects on Soil Nutrient Adequacy Levels and Cassava Yield of Smallholder Farmers in Northern Zambia

Cassava is a staple food and a major source of income for many smallholder farmers. However, its yields are less than 6 t ha−1 compared to a potential yield of 20–25 t ha−1 in Zambia. Understanding cropping practices and constraints in cassava production systems is imperative for sustainable intensification. Therefore, a survey of 40 households each with three fields of cassava at 12, 24, and 36 months after planting (MAP) was conducted. Analyzed soil data, leaf area index (LAI), intercepted photosynthetically active radiation, and management practices from 120 fields were collected and subjected to descriptive statistics. To explain yield differences within the same cassava growth stage group, the data were grouped into low- and high-yield categories using the median, before applying a nonparametric test for one independent sample. Stepwise regressions were performed on each growth stage and the whole dataset to determine factors affecting tuber yield. Cassava intercropping and monocropping systems were the main cropping systems for the 12 and 24–36 MAP, respectively. Cassava yields declined by 209 and 633 kg ha−1 at 12 and 36 MAP due to soil nutrient depletion for each year of cultivation until field abandonment at 8–9 years. Fresh cassava yields ranged from 3.51–8.51, 13.52–25.84, and 16.92–30.98 t ha−1 at 12, 24, and 36 MAP, respectively. For every one unit increment in exchangeable K (cmol (+)/kg soil), cassava yield increased by 435, 268, and 406 kg ha−1 at 12, 24, and 36 MAP, respectively. One unit increment of magnesium (cmol (+)/kg soil) gave the highest yield increase of 525 kg ha−1 at 24 MAP. The low levels of soil organic carbon explained the deficient nitrogen in cassava fields, which limits the LAI growth and consequently reduced intercepted radiation and low yields. The effect of exchangeable K on growth was limited by the moderate availability of Mg and low N, thus the need for balanced fertilizer regimes.

Socio-environmental dynamics in the central Atacama desert (22°S) during the late Holocene

In the Central Atacama Desert (22°-24°S; henceforth CAD), around 3700 cal yrs BP, human economies begin to transition from relying mostly on hunting and gathering to increasingly incorporating horticulture and pastoralism became more intensive during the Late Intermediate Period (LIP; beginning at ca. 1050 cal yrs BP/900 AD). In this extreme environment, the well-being of past and present farming and herding communities is directly tied to water availability. The lack of proper paleoclimatic/environmental records in terms of their temporal/spatial resolution impeded evaluation whether sedentarization was synchronous, in some degree, with the amelioration of dry conditions recorded during the Late Holocene at millennial timescales. The present paper thus aims (1) to reconstruct the past environmental and climatic dynamics in the CAD (22°S) during the late Holocene at millennial to sub-centennial scales based on the pollen record of fossil rodent middens of Cuesta Chita site and; (2) to discuss their possible relationship to changes in cultivation and water management as seen at the archaeological sites of Topaín, Paniri and Turi, located in the Salado River basin. The CCH rodent midden pollen record reflects wetter (drier) than present phases around 4400, 3650, 3000, 2200–2100, 1600, 855–840, 520–450 and 100 cal yrs BP (980, 450-115 cal yrs BP). By the time that wetter-than-present conditions occurred in the CAD (Formative Period, 3500-1050 cal yrs BP), local communities had already developed small-scale horticultural practices, yet they did not develop extensive or intensive agricultural practices. Indeed, historical processes leading to economic transformations and the rapid adoption of intensive agriculture throughout the CAD after 1000 cal yrs BP occurred and were probably favored by wetter than present conditions, suggesting positive correlations between climatic and cultural change. However, these correlations are complex and non-deterministic. In fact, decreased moisture between 650 and 600 cal yrs BP in the Turi Basin was met by agropastoralists at Topaín with complex local strategies that included changing water management practices and significantly extending farmed lands. Similarly, the Topaín fields were abandoned during a period of much-wetter-than-present conditions. The chronologically fine-grained comparison of the CCH and archaeological records reveals that the relationship between climate and culture is complex, non-deterministic, and historically contingent, with examples of agricultural expansion during a time of water stress, and the abandonment of fields during a time of abundance.

Assessing the impact of large-scale farmland abandonment on the habitat distributions of frog species after the Fukushima nuclear accident.

Rice paddies function as wetlands; therefore, abandoned paddy fields cause a loss of habitats for aquatic species, such as amphibians. Following the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, paddy fields around the plant were abandoned and rapidly dried. To identify the impact of large-scale abandonment of paddy fields on the habitats of frogs, we investigated changes in the distributions of four frogs that breed in paddy fields using niche modeling and field surveys. The spatial distributions of suitable habitats before and after the accident for each frog were created using MaxEnt. In the area where rice cropping was restricted due to radioactive contamination, the areas of suitable habitats decreased for Pelophylax porosus porosus but increased or remained unchanged for other frogs after the accident. Additionally, field surveys conducted in 2014 indicated that the ratios of breeding sites in the area where rice cropping was restricted were significantly lower for P. p. porosus and Hyla japonica than outside this area. Thus, 3years after the accident, one species strongly dependent upon paddy fields rapidly disappeared over a large area. Although amphibian populations or monitoring data were not available to examine changes directly after the accident in the study area, this research showed that the combination of niche modeling and field survey was effective for predicting species response after an accident and revealed that large-scale disasters sufficient to disrupt agricultural activity could markedly change the distribution of species reliant on habitats created by human activity.

Operator Reviews Decommissioning Options for Deepwater Flowlines and Risers

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 30397, “Deepwater Flowlines and Risers Decommissioning,” by Azam Syah Jaafar, Ahmad Taqiyuddin Obaidellah, and Khairul Anuar Karim, Petronas, prepared for the 2020 Offshore Technology Conference Asia, originally scheduled to be held in Kuala Lumpur, 2–6 November. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. The complete paper reviews an operator’s deepwater field project offshore Mauritania, for which several techniques were considered with respect to decommissioning a subsea pipeline system at water depths of 700 to 960 m. Options included preservation for potential future use, leaving in situ, and full recovery. The paper covers only the operator’s deepwater subsea flowline and riser decommissioning experiences and reviews activities from planning and concept to operational activities such as pigging, flushing, cleaning, disconnection, and retrieval. Case Study The operator’s deepwater field is 80 km from the Mauritanian coastline. It has been in production since 2006 but has become uneconomical. The operator decided to cease production and subsequently conducted a field abandonment and decommissioning (A&D) study. The field was developed using subsea wells, manifolds, umbilicals, flexible flowlines, and flexible risers tied back to a permanently moored floating production, storage, and offloading (FPSO) vessel at a depth of approximately 800 m. The FPSO was moored by an external turret connected to three clusters of mooring lines attached to piles in the seabed. All subsea wells were connected to the FPSO by five flexible pipeline systems (including dynamic flexible risers) and one umbilical system. All flexible pipeline systems were meant for the transportation of production fluids, water injection, gas injection, and gas-lift services. Because the FPSO is a turret-moored type, in which the turret is externally positioned at the FPSO’s bow, all flexible risers were designed to decouple the load and motion at hangoff from touch-down point with a lazy-wave configuration. The lazy-wave configuration was obtained by clamping sets of buoyancy modules on the risers. The execution of abandonment and decommissioning work has been divided into two main scopes: restoration of well integrity by installation of deep and shallow set plugs and FPSO disconnection and demobilization, which covers subsea facilities, risers, umbilical and flowline flushing and cleaning, topside process plant flushing and cleaning, pipeline systems and mooring-lines disconnection and retrieval, and FPSO sailaway. A plan for disposal of all resulting waste also was incorporated. Guidelines, Rules, and Regulations No universal statutory requirement, standard, or recommended practice existed to fully address pipeline decommissioning. Nevertheless, countries with more-established offshore industries (e.g., Norway, United Kingdom, US) have developed local legislation and practices that have been implemented in these respective jurisdictions.

Enhanced Oil Recovery: Projects Planning Strategy in Angolan Oilfields

Hydrocarbon exploration in Angola commenced in 1910 with its first oil recovered in 1955. The proven reserves in Angola are estimated to reach up to 13 billion barrels (2.1 billion m3). Most of the Angolan oil fields are mature or maturing and some are or may be abandoned due to unprofitable recovery limit beyond the conventional type of oil production. The oil recovery is mainly by primary and secondary recovery methods. Apart from the issue of maturity, there is increasing energy demand due to population growth and difficulties in discovering and developing new fields as alternatives to the current oil fields. For incremental and sustained production rate of these fields and in addition to instability of oil prices and concerns about future oil supply, Angola has started to work towards developing affordable and efficient technologies capable of recovering residual oil in reservoirs as well as extend the life of many current fields which can be achieved through the implementation of enhanced oil recovery (EOR). Therefore, this paper discusses the EOR planning strategy from project selection, project implementation and optimization, and field abandonment. It further highlights the mutual benefits that may be derived from a cross-collaboration between the government and other stakeholders in Angola.

Enhanced oil recovery: Projects planning strategy in Angolan oilfields

Hydrocarbon exploration in Angola commenced in 1910 with its first oil recovered in 1955. The proven reserves in Angola are estimated to reach up to 13 billion barrels (2.1 billion m3). Most of the Angolan oil fields are mature or maturing and some are or may be abandoned due to unprofitable recovery limit beyond the conventional type of oil production. The oil recovery is mainly by primary and secondary recovery methods. Apart from the issue of maturity, there is increasing energy demand due to population growth and difficulties in discovering and developing new fields as alternatives to the current oil fields. For incremental and sustained production rate of these fields and in addition to instability of oil prices and concerns about future oil supply, Angola has started to work towards developing affordable and efficient technologies capable of recovering residual oil in reservoirs as well as extend the life of many current fields which can be achieved through the implementation of enhanced oil recovery (EOR). Therefore, this paper discusses the EOR planning strategy from project selection, project implementation and optimization, and field abandonment. It further highlights the mutual benefits that may be derived from a cross-collaboration between the government and other stakeholders in Angola.

Identification of Abandoned Jujube Fields Using Multi-Temporal High-Resolution Imagery and Machine Learning

The jujube industry plays a very important role in the agricultural industrial structure of Xinjiang, China. In recent years, the abandonment of jujube fields has gradually emerged. It is critical to inventory the abandoned land soon after it is generated to adjust agricultural production better and prevent the negative impacts from the abandonment (such as outbreaks of diseases, insect pests, and fires). High-resolution multi-temporal satellite remote sensing images can be used to identify subtle differences among crops and provide a good tool for solving this problem. In this research, both field-based and pixel-based classification approaches using field boundaries were used to estimate the percentage of abandoned jujube fields with multi-temporal high spatial resolution satellite images (Gaofen-1 and Gaofen-6) and the Random Forest algorithm. The results showed that both approaches produced good classification results and similar distributions of abandoned fields. The overall accuracy was 91.1% for the field-based classification and 90.0% for the pixel-based classification, and the Kappa was 0.866 and 0.848 for the respective classifications. The areas of abandoned land detected in the field-based and pixel-based classification maps were 806.09 ha and 828.21 ha, respectively, accounting for 8.97% and 9.11% of the study area. In addition, feature importance evaluations of the two approaches showed that the overall importance of texture features was higher than that of vegetation indices and that 31 October and 10 November were important dates for abandoned land detection. The methodology proposed in this study will be useful for identifying abandoned jujube fields and have the potential for large-scale application.

Spatially Continuous Land-Cover Reconstructions Through the Holocene in Southern Sweden

Climate change and human activities influence the development of ecosystems, with human demand of ecosystem services altering both land use and land cover. Fossil pollen records provide time series of vegetation characteristics, and the aim of this study was to create spatially continuous reconstructions of land cover through the Holocene in southern Sweden. The Landscape Reconstruction Algorithm (LRA) was applied to obtain quantitative reconstructions of pollen-based vegetation cover at local scales, accounting for pollen production, dispersal, and deposition mechanisms. Pollen-based local vegetation estimates were produced from 41 fossil pollen records available for the region. A comparison of 17 interpolation methods was made and evaluated by comparing with current land cover. Simple kriging with cokriging using elevation was selected to interpolate the local characteristics of past land cover, to generate more detailed reconstructions of trends and degree of variability in time and space than previous studies based on pollen data representing the regional scale. Since the Mesolithic, two main processes have acted to reshape the land cover of southern Sweden, originally mostly covered by broad-leaved forests. The natural distribution limit of coniferous forest has moved southward during periods with colder climate and retracted northward during warmer periods, and human expansion in the area and agrotechnological developments has led to a gradually more open landscape, reaching maximum openness at the beginning of the 20th century. The recent intensification of agriculture has led to abandonment of less fertile agricultural fields and afforestation with conifer forest.

Celtic fields en marke- en malebossen

Abstract Iron Age Celtic fields and medieval common woodlands: some considerations on their topological relationship and chronological transition Until recently, Celtic fields could only be distinguished on aerial photographs, especially in open landscapes like arable fields and heathlands. With the emergence of lidar data, however, a new set of these late prehistoric fields have been discovered in afforested areas. A closer examination of the about two hundred known Celtic fields in The Netherlands revealed that about 50-60 percent of them are situated in former common woodlands dating from the later Middle Ages. Apparently, there is a causal connection between the two. After the abandonment of the Celtic fields in the Early Roman period woodland regeneration on these nutrient rich soils was probably more prominent than on the surrounding podzolised soils. Archeological excavations and modern-day field research reveal that there could have been possible interphase of early and high medieval coppice woods on former Celtic fields, which were used for large-scale charcoal production supplying local and regional iron industries. This would diachronically and topographically connect three main narratives of Dutch sandy landscapes i.e. late prehistoric working landscapes, early and high medieval iron production and late medieval and early modern common woodlands.

Native Perennial Plants Colonizing Abandoned Arable Fields in a Desert Area: Population Structure and Community Assembly

In recent years, the phenomenon of abandonment of arable fields has increased in Saudi Arabia due to low soil fertility, drought, low rainfall, high levels of evapotranspiration, soil salinization, and low level of groundwater. We evaluated the effect of agricultural land abandonment on soil properties, perennial vegetation composition, and population structure in the Al-Kharj region, Saudi Arabia. A total of 11 perennial plant species belonging to 9 families and 11 genera were detected in the different abandoned fields of the study area. Four plant communities were identified after the application of the detrended correspondence analysis (DCA) ordination. The indicator species were (1) Seidlitzia rosmarinus—Zygophyllum hamiense, (2) Traganum nudatum—Seidlitzia rosmarinus, (3) Traganum nudatum—Prosopis farcta, and (4) Calligonum comosum—Pulicaria undulata. Results of the soil analysis showed significant differences in soil texture, pH, salinity, and nutrient content among the four recognized plant communities. Demographic analysis indicated that populations of Zygophyllum hamiense and Calligonum comosum tended to be either inverse J-shaped or positively skewed which may have indicated rapidly-growing populations with high reproductive capacity. Conversely, the size–frequency distribution of Traganum nudatum, S. Rosmarinus, and Prosopis farcta was approximately symmetrical (i.e., bell-shaped). The present study sheds light on the necessity of managing abandoned agricultural fields for restoring and improving rangelands with native species that are adapted to the local conditions such as low water demand.

Distribution and conservation status of the herpetofauna of Dugi Otok Island, Croatia

The first overview of the amphibians and reptiles of Dugi Otok Island, Northern Dalmatia, is presented, based on the published data and new records collected during the last twenty years. A total of 15 species are present on the island, of which only one was not recorded on our surveys. In comparison to other islands of Northern Dalmatia, Dugi Otok is the second most diverse island in terms of herpetofauna, just after Pag Island. The main threats to the amphibians and reptiles on the island are the disappearance and degradation of aquatic habitats, the abandonment and succession of traditional agricultural fields and olive groves and the increasing presence of several invasive species.

Goat Grazing for Restoring, Managing, and Conserving “Satoyama”, a Unique Socio-Ecological Production Landscape

Agricultural intensification and socioeconomic changes over several decades have generated many abandoned fields. These changes have led to reduce plant and animal biodiversity, as well as associated loss of ecosystem services, and represent deterioration of a unique socio-ecological production landscape known as “Satoyama” in Japan. Appropriate management measures should be implemented to restore these abandoned fields. The objectives of this study were to: 1) determine the effect of goat grazing on vegetation dynamics and animal performance in response to different stocking rates over a five-year period; and 2) evaluate the economic potential of weed management through goat grazing by comparing this method to mowing with a brush cutter. We found that goat grazing changed vegetational composition, increased the number of plant species, and improved plant diversity in the abandoned field, although stocking rate had little effect on plant diversity. Goat grazing changed vegetation quality, even though goats maintained their nutritional status and body weight over five years. Goat grazing showed economic advantages over mowing during a relatively short period (up to 8–12 days per 1,000 m2). Overall, we found that goats would be ecologically and economically useful in restoring, managing, and conserving agricultural fields. However, a more comprehensive approach is still necessary for conserving “Satoyama”. Combination of grazing, mowing with a machine and prescribed burning may be more effective, and animal and biofuel production in these field would be a solution for reducing field abandonment.

Spatial Heterogeneity of Farmland Abandonment in the Sichuan Province, China

Urbanization and regional geomorphological and agricultural conditions have caused rural hollowing out and a large number of farms to be abandoned, which is a big obstacle to food security and rural industrial development. Sichuan Province is representative of national major grain producing areas and high-quality cultivated protected land in China. This paper reveals the spatial heterogeneity of farmland abandonment in the Sichuan Province. In total, 455 random sample plots were investigated to explore spatial heterogeneity of abandoned farmland in Sichuan Province. In each sample plot, farmland and abandoned farmland patches were mapped. The rate of paddy field abandonment (RPFA), the rate of non-irrigated farmland abandonment (RNFA), and the rate of farmland abandonment (RFA) were calculated as indicators of farmland abandonment. Our results reveal the spatial heterogeneity of abandoned farmland in Sichuan Province, and the clustering characteristics of spatial cold- and hot spots of the RFA. The findings from this study may have importance in rural infrastructure construction and the implementation of a rural revitalization strategy, as well as in making policies to curb abandonment of farmland. The spatial heterogeneity of farmland abandonment revealed in this study may contribute to sustaining food security and farmland protection in China.

The Availability of Non-Timber Forest Products under Forest Succession on Abandoned Fields along the Wild Coast, South Africa

Large swathes of arable fields have been abandoned in many areas of the world over the last few decades driven by a multitude of local and broader-scale factors. Many former fields experience a change in vegetation composition and structure post-abandonment, typically through a process of plant succession. The changes in species and abundance mean that the nature and quantity of ecosystem services provided by the former fields also varies. We examined the types of provisioning services obtained from non-timber forest products (NTFPs) with increasing age since field abandonment. We sampled 43 former fields ranging in age since abandonment from approximately 7 to 55 years, and seven plots in intact forests. We held seven focus group discussions with local residents to determine uses of species found in the former fields. Plant cover and species richness increased with former field age, although old field community composition was also influenced by soil chemistry. Of the 177 species recorded, 70 (40%) had one or more uses, spanning six NTFP categories namely, food, building, medicinal, craft, cultural and energy. The number of NTFP species increased with increasing age of the former field, but the proportion of NTFP species declined from 80% in the youngest former fields to 65% in the oldest ones, which were similar to the 63% recorded within intact forests. The youngest former fields had more medicinal species than the older ones, as the abundance and diversity of herbaceous species declined with increasing woody plant cover. Species used for building and food (especially fruits) peaked when the former fields became dominated by woody plants. NTFPs used for craft were most abundant in the oldest sites.

Long‐term dynamics of shrub facilitation shape the mixing of evergreen and deciduous oaks in Mediterranean abandoned fields

Abstract Recovery of Mediterranean forests after field abandonment is a slow process, even without propagule limitations. This is mainly due to stressful conditions for seedling establishment. In this context, shrubs play a critical role in facilitating tree recruitment, but how this process unfolds after field abandonment is not entirely known. We evaluated the long‐term dynamics of facilitation by the nurse shrub Retama sphaerocarpa in the recruitment of two ecologically contrasting oaks, the evergreen Quercus ilex and the deciduous Quercus faginea. Thirty years after field abandonment, we dated shrubs and oaks established in an old field to estimate the annual recruitment rates and investigate temporal recruitment patterns. For oaks, we differentiated recruitment at two microsites: open areas or under shrub. To assess how nurse shrubs modulated environmental stressors, we modelled oak recruitment as a function of climatic variables. For the evergreen oak, we assessed these effects within each microsite. Finally, we estimated the annual interaction index between shrubs and evergreen oak juveniles as a function of climatic conditions. Each species showed different recruitment pulses during colonization. Recruitment rate was the highest for the shrub, followed by the evergreen oak. Oak colonization under shrubs was appreciable 20 years after field abandonment, when shrub cover reached 2.2%, and concentrated under medium and large shrubs older than 7 years. Shrubs not only accelerated evergreen oak colonization but also attenuated the fluctuations of recruitment pulses. For the evergreen oak, the interaction index indicated facilitation dominance in years with more arid summers (precipitation < 47 mm and heat waves longer than 8 days) and competition in wetter summers. Synthesis. Oak colonization in Mediterranean abandoned fields progressed slowly, and only two decades after abandonment pioneer shrub population grew to a level in size and number that could effectively trigger facilitation and accelerate tree recruitment. The shrub nurse effect was unbalanced between oak species, only benefiting the evergreen oak, and it was more prevalent in arid years. Our study illustrates the build‐up of shrub facilitation during forest recolonization and the varying nature of this process among climatically different years and ecologically distinct species. This information provides insights for assessing and managing Mediterranean forest recovery.

Abiotic, present-day and historical effects on species, functional and phylogenetic diversity in dry grasslands of different age.

Many grasslands have disappeared over the last century as a result of anthropogenic land use intensification, while new patches are emerging through abandonment of arable fields. Here, we compared species (SD), functional (FD) and phylogenetic (PD) (alpha) diversity among 272 dry grassland patches of two age-classes: old and new, with the new patches being dry grasslands established on previous intensively managed fields during the last 30 years. We first compared SD, FD and PD, between patches of different age. Then, we performed generalized linear models to determine the influence of abiotic, present-day and historical landscape configuration variables on SD, FD and PD. By measuring abiotic variables, we explained the effect of environmental filtering on species diversity, whereas the present-day and historical landscape configuration variables were included to describe how the spatial and temporal configuration of the patches influence patterns of species. Finally, we applied partial regressions to explore the relative importance of abiotic, present-day and historical variables in explaining the diversity metrics and how this varies between patches of different ages. We found higher SD in the old compared to the new patches, but no changes in FD and PD. SD was mostly affected by abiotic and present-day landscape configuration variables in the new and the old patches, respectively. In the new patches, historical variables explained variation in the FD, while present-day variables explained the PD. In the old patches, historical variables accounted for most of the variation in both FD and PD. Our evidence suggests that the relative importance of assembly processes has changed over time, showing that environmental filtering and changes in the landscape configuration prevented the establishment of species in the new patches. However, the loss of species (i.e. SD) is not necessarily linked to a loss of functions and evolutionary potential.

Projected trends of soil organic carbon stocks in Meghalaya state of Northeast Himalayas, India. Implications for a policy perspective

Agricultural and forestry activities can affect soil organic carbon (SOC) levels and CO2 emissions from terrestrial ecosystems due to land use changes. In Northeast Himalayas, studies on the effects of forest conversion to temporary agricultural lands (jhum) on the loss of SOC and soil quality degradation have received the attention of policy makers and scientific research. Presently, local communities are now oriented towards the settled plantations systems with modern cash crops such as tea and rubber, that could act as potential SOC sinks. However, no information on SOC dynamics and simulation studies after land-use change from temporary agricultural lands (jhum) to settled cultivations and under climate change (CC) conditions are available for the Meghalaya state. Applying the RothC model, we focused on four different scenarios including the conversion from jhum to settled cultivation (rubber plantations and tea gardens), as well as continuous jhum cultivation and jhum to jhum with a period of secondary succession. Simulations under CC conditions indicated that SOC stocks significantly increased by 1.20 t C ha−1 yr−1 in tea gardens compared to rubber and jhum scenarios. Conversely, SOC stocks slightly decreased by 0.07 t C ha−1 yr−1 in rubber plantations, while the regrowth of a natural vegetation cover as secondary succession following the abandonment of the jhum fields, showed a lower SOC decrease (0.18 t C ha−1 yr−1) compared to the continuous jhum cultivation (0.24 t C ha−1 yr−1). Thus, for CC mitigation in a policy perspective, tea gardens could represent the best land use to store increasing amounts of SOC in the long-term perspective and optimize farmers' incomes, while in rubber plantations SOC storage is limited in time. Jhum cultivation can benefit in terms of productivity and profitability by extending the duration of the secondary succession period.

Greenhouse Gas Emission of Electricity Generation and Field Abandonment Scenarios Using Empty Fruit Bunches at a Palm Oil Mill, Surat Thani Province, Thailand

In Indonesia, Malaysia, and Thailand, the pile abandonment of empty fruit bunches (EFBs) in the fields of palm oil mills is a common practice. This practice results in environmental issues such as generation of unpleasant odors and methane production due to anaerobic decomposition. In the present study, an abandoned moist EFB sample from Rubber Oil Co. Limited, a palm oil mill in the Thachi sub-district municipality, Surat Thani Province, southern Thailand, was collected and sun dried for physical analysis. The bulk density at 13.2% moisture content was 0.118 kg/L. Greenhouse gas (GHG) emissions for electricity generation and methane production due to anaerobic decomposition were compared applying life cycle assessment. A cargo capacity of 621 kg of EFBs and a 59 km distance to the Surat Thani Biomass Power Plant in Surat Thani province were adapted with reference to Thailand’s GHG emission factors. The system boundary included the EFBs in the palm oil mill and the nearest power plant. The CO2 equivalent GHG emissions per kg of EFB for the transportation, generation, and field abandonment (methane emission) were 0.077, -0.877, and 2.136 kg-CO2e, respectively; a sum of -0.8 kg-CO2e emission via electricity generation use was noted as a significant environmental advantage.

Identifying plant and environmental indicators of ancient and recent calcareous grasslands

Dry calcareous grasslands are among the most species-rich habitats in Central Europe, harbouring numerous threatened species. Because of their strong decline, they are being protected under the European Habitats Directive. However, apart from this general decline, new grasslands developed after the abandonment of arable fields on marginal land over the course of the last few centuries or even decades. The main question of this study was which species may indicate the age of a dry calcareous grassland habitat in the Franconian Jurassic mountains near Kallmünz. We compared the diversity parameters and nature conservation value of both grassland types. Additionally, we searched for differences in habitat and soil parameters. Furthermore, we asked if there is a general pattern of indicator species among available studies on ancient (i.e. those continuously used as pastures at least since 1830) and recent (i.e. those temporarily farmed as arable fields after 1830) calcareous grasslands. We compiled a list of indicator species of both ancient and recent grasslands in the study region. Comparison with other studies leads to the conclusion that there are not many species that clearly indicate grassland age across different regions (the best indicators are Carex caryophyllea, Cirsium acaule and Hippocrepis comosa for ancient grasslands, and Agrimonia eupatoria and Astragalus glyciplyllos for recent grasslands). Ancient grasslands harbour a somewhat greater number of threatened species than recent grasslands. Many species of the ancient grasslands under study can be considered relict species of steppic grasslands or open pine forests (e.g. Hippocrepis comosa, Pulsatilla vulgaris, Teucrium chamaedrys, Teucrium montanum and Thymus praecox). Recent grasslands also harbour rare and endangered species, especially disturbance-tolerant relicts of former arable use (e.g. Melampyrum arvense) and may therefore be of high conservation value, too. The average number of species per plot is greater in ancient grasslands. However, the most species-rich plot (46 species of vascular plants within a 4-m2 quadrat) was found in a 60 years old grassland. Arable cultivation in the past has altered the physical and chemical properties of the soil of recent grasslands. In general, ancient grasslands occur on nutrient-poorer and less calcium-rich soils with high water holding capacity. High water holding capacity is connected with high humus content, which increases the importance of ancient grasslands for carbon storage. The challenges and benefits of differentiating grasslands of different age in the management of protected areas and landscape planning (e.g. the identification of High Nature Value farmland) are discussed.

Changes in spider diversity and community structure along abandonment and vegetation succession in rice paddy ecosystems

Field abandonment is a new threat to the biodiversity of agricultural land, but its impacts on arthropod communities remain unclear. We investigated how field abandonment influences spider abundance and diversity in rice paddy ecosystems. We collected spiders in paddy fields and six types of abandoned fields with different combinations of vegetation successional stage (early, middle, or late) and soil water content (wet or dry) in Ibaraki Prefecture, Japan. The abundance and species richness of cursorial spiders were higher in the abandoned fields than in the paddy fields, but there was no difference in the case of orb-weavers. Total spider abundance decreased with increasing successional stage, but the responses differed between orb-weavers and cursorial spiders: the abundance of orb-weavers decreased in the middle stage, whereas that of cursorial spiders decreased in the late stage. Soil water content affected only the abundance of orb-weavers: abundance was higher on wet soil than on dry soil. Species richness was not affected by either vegetation succession or soil water content. On the other hand, an individual-based species-accumulation curve showed that rarefied species richness tended to be greater in abandoned fields at the late stage. Ordination analysis showed that species composition clearly differed among paddy and abandoned fields at different successional stages. Our findings suggest that spider abundance and diversity are higher in abandoned fields than in cultivated fields, and that species composition varies depending on field abandonment and succession. Therefore, maintaining cultivated fields and abandoned fields at different successional stages can maintain a high diversity of spiders across rice paddy ecosystems.