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Volcanic soils are well-known to have a high agronomical value, and in Sumatra, Mt. Kerinci volcanic soils produce one of the highest quality tea and rice. Declining soil organic carbon (C) and high phosphorus (P) retention are two main issues in volcanic soils in the area. Thus, this study aimed to study the dynamic of C) and P content in volcanic soils and to find the main controls of their variation from geochemical signatures. The soils of Mt Kerinci present a unique environment as one part of the area was converted from forest to tea plantation for about 100 years, and a nearby field had been used for paddy rice cultivation for about 200 years. The study was conducted in the Mt Kerinci area covering 5,922 ha in the north comprise of paddy soils (ps) and north tea soils (nts) and the south slope (south tea soils= sts). Soil samples were collected on a grid of 500 × 500 m under tea and paddy (n = 206 samples) at 0–20 and 20–40 cm depth. All soils have similar pH in H2O, but pH in KCl paddy soils (ps) > north tea soils (nts) > south tea soils (sts). The average content of soil organic Carbon (SOC) in paddy soils was 50% less than in the soils of tea plantations. The labile organic carbon content in paddy soils were lower than in soils of tea plantations. Most C was chemically bound to the metal complex. Higher P retention occurred in all soils. The CaO/TiO2 index indicated a weathering sequence of ps > nts > sts. Soil weathering controlled P retention with an increasing P retention as the soils weathered. Overall, the study suggests that cultivation in volcanic soils influenced the geochemical properties of the soils and subsequently their C and P contents. [ABSTRACT FROM AUTHOR]

Soil physicochemical properties play a key role in plant growth and development; however, owing to land use change and successive planting, long-term changes in soil physicochemical properties are rarely reported. The objective of this study was to analyze changes in soil physicochemical properties caused by the conversion of Masson pine forests to Eucalyptus plantations and the successive planting of first-, second-, and third-generation Eucalyptus plantations in China using a space-for-time substitution method. The results demonstrated significant differences in soil physicochemical properties between Masson pine forest (MP) and second-generation (G2) and third-generation (G3) Eucalyptus plantations at 0-20 and 40-60 cm soil depths (p<0.05). Alkaline hydrolytic nitrogen levels were significantly lower in G3 than in first-generation (G1) Eucalyptus plantations at 0-20 cm soil depth (p<0.05). Available phosphorus, available potassium, and organic matter levels were significantly lower in G2 and G3 than in MP at a 0-20 cm soil depth (p<0.05). The pH and bulk density were significantly lower in G2 and G3 than in MP at 0-20, 20-40, and 40-60 cm soil depths (p<0.05). However, stable isotope 15N abundance was significantly higher in G2 and G3 than in G1 at 0-20 and 20-40 cm soil depths (p<0.05). TP was defined as MP

Although one of the main purposes of protected areas is to provide viable habitats for species, the effectiveness of protected areas in retaining the landscape's ecological integrity is highly variable (Coetzee, 2017; Watson et al., 2014). As demand for landscape conservation from NGOs and governments increases and financial resources to support conservation remain limited, more careful consideration of the variability in ecological condition of the landscape is needed to design efficient protected area networks. Keywords: 30 × 30; additionality; Aichi targets; biodiversity conservation; counterfactual; landscape conservation; land-use conversion; reserve selection; 30 para el 30; adicionalidad; conservación de la biodiversidad; conservación del paisaje; conversión del uso de suelo; hipotético; objetivos de Aichi; selección de reserva; > ; , , "30 by 30" , , , , , EN 30 × 30 additionality Aichi targets biodiversity conservation counterfactual landscape conservation land-use conversion reserve selection 30 para el 30 adicionalidad conservación de la biodiversidad conservación del paisaje conversión del uso de suelo hipotético objetivos de Aichi selección de reserva > , , "30 by 30" , , , , , 1 10 10 10/04/22 20221001 NES 221001 INTRODUCTION With the world's biodiversity in peril (IPBES, 2019), many nongovernmental organizations (NGOs) and government conservation agencies are focusing on biological conservation through establishing protected areas. [Extracted from the article]

Soil is the largest carbon reservoir in terrestrial ecosystems, and thus minor changes in it can dramatically affect atmospheric CO2 concentrations. In the northwestern arid zone of China, the prediction of soil organic carbon (SOC) changes is often limited by the scarcity of soil samples and the scale and depth of research, which limit the understanding of carbon cycling processes in arid zone terrestrial ecosystems. Therefore, this study produced digital soil maps of SOC stocks (SOCS) for two periods (1980‐1990 and 2010‐2020) at a 90‐m resolution based on historical soil profile data and a random forest model. The results showed that the prediction accuracy for SOCS in the topsoil (0–30 cm) was superior to that of the subsoil (30–100 cm). Among them, the mean annual evapotranspiration, normalized difference vegetation index during the growing season, multi‐year mean temperature, and clay content were the main environmental factors affecting the spatial distribution of SOCS. In the past 30 years, the SOCS of the northwestern arid zone has decreased by 585.50 Tg, with a mean decline of 19.52 Tg C yr−1. The changes in SOCS caused by land‐use conversion and reductions in SOCS were further shown to be attributable to grassland desertification and agricultural reclamation. These findings are valuable for exploring the carbon cycle in terrestrial ecosystems in the context of global climate change and for achieving China's goal of carbon neutrality. [ABSTRACT FROM AUTHOR]

Afforestation on cultivated farmlands causes major shifts in the nitrogen (N) cycle. The consequences of large‐scale Zanthoxylum bungeanum afforestation on spatio‐temporal patterns of soil N mineralization and inorganic N (ION) availability have not been reported. Moreover, the regulatory roles of microbial biomass and soluble organic N (MBN and SON) in the N cycle are poorly characterized in soils below 20 cm. To investigate the long‐term effects of afforestation on the governing mechanism of vertical N dynamics, a 0–100 cm soil profile was collected from a chronosequence of Z. bungeanum plantations aged 8‐year (H8), 15‐year (H15), 20‐year (H20) and 28‐year (H28), as well as adjacent farmland and abandoned‐land (28‐year) as controls in an arid valley in Southwest China. With increasing stand age, conversion of farmland to Z. bungeanum plantations significantly improved soil organic carbon, available nutrients, and all N forms. These impacts were more evident in the topsoil (0–20 cm) than in the subsoil layers. MBN and SON contents improved by 1.42‐fold and 1.34‐fold in H28, respectively, compared to H8. Net N mineralization (1.31‐fold), net nitrification rates (1.30‐fold), and total ION (1.31‐fold) content followed similar trends of increase along with the stand age. Correlation and redundancy analysis also established a positive relationship and demonstrated that increased ION availability is due to improved MBN, SON, and urease activity with the plantations age. Although the nitrate‐N content was highest in abandoned‐land, its content also increased steadily in Z. bungeanum plantations with the stand age. A relatively low ammonium/nitrate ratio (0.331) in H28 advocated improved N supply via nitrification as well as low N leaching risks from plantations. The spatial investigation provided novel insights into controls of N cycle and suggested converting farmland to Z. bungeanum plantations is a suitable approach for restoring soil N. [ABSTRACT FROM AUTHOR]

Soil aggregation and aggregate-associated carbon (C) play an essential function in soil health and C sequestration. Arbuscular mycorrhizal fungi (AMF) are considered to be primary soil aggregators due to the combined effect of extraradical hyphae and glomalin-related soil proteins (GRSPs). However, the effects of diversity and network complexity of AMF community on stability of soil aggregates and their associated C under long-term climate change (CC) and land-use conversion (LUC) in relatively high-latitude regions are largely unexplored. Therefore, an 8-year soil plot (with a 30-year cropping history) transplantation experiment was conducted to simulate CC and LUC from cropland to fallow land. The results showed that Glomus, Paraglomus, and Archaeospora were the most abundant genera. The diversity of AMF community in fallow land was higher than cropland and increased with increasing of mean annual temperature (MAT) and mean annual precipitation (MAP). Fallow land enhanced the network complexity of AMF community. The abundance families (Glomeraceae and Paraglomeraceae) exhibited higher values of topological features and were more often located in central ecological positions. Long-term fallow land had a significantly higher hyphal length density, GRSP, mean weight diameter (MWD), geometric mean diameter (GMD), and C concentration of GRSP (C-GRSP) than the cropland. The soil aggregate associated soil organic carbon (SOC) was 16.8, 18.6, and 13.8% higher under fallow land compared to that under cropland at HLJ, JL, and LN study sites, respectively. The structural equation model and random forest regression revealed that AMF diversity, network complexity, and their secreted GRSP mediate the effects of CC and LUC on C-GRSP and aggregate-associated SOC. This study elucidates the climate sensitivity of C within GRSP and soil aggregates which response symmetry to LUC and highlights the potential importance of AMF in C sequestration and climate change mitigation. [ABSTRACT FROM AUTHOR]

Soil structure and organic carbon are key factors that reflect soil quality in sustainable agricultural production. Many studies have concentrated on soil aeration under intensive anthropogenic agricultural practices, but the relationship between soil aggregate stability and soil organic carbon (SOC) functional groups is poorly understood, particularly in degraded greenhouse vegetable fields converted from paddy fields. To solve this problem, soil samples were collected from local vegetable fields and adjacent paddy fields. Conventional open‐air vegetable fields and greenhouse vegetable fields, both with a 6–8‐year cultivation history following conversion from paddy fields, were considered. SOC functional groups were characterised by 13C cross‐polarisation magic‐angle‐spinning nuclear magnetic resonance (13C CPMAS NMR). The results showed that the mean weight diameter (MWD) values of water‐stable soil aggregates in the open‐air vegetable fields and greenhouse vegetable fields decreased by 64.6% and 66.7%, respectively, compared with those in the paddy fields. Similar results were obtained for the soil aggregate distribution, and soil aggregates in the greenhouse vegetable fields and open‐air vegetable fields were mainly in the 0.25–2 mm size classes. Among all SOC functional groups, O‐alkyl C exhibited the greatest decrease after the conversion of paddy fields to vegetable fields, no matter whether greenhouse vegetable fields or open‐air vegetable fields. The degradation of soil structure decreased the physical protection of SOC functional groups by soil aggregates, and therefore, decreased the total SOC content and labile C functional group fractions in bulk soil. At the soil aggregate scale, the decrease of O‐alkyl C mainly occurred in microaggregates (0.053–0.25 mm), while aromatic C decreased significantly in macroaggregates (>0.25 mm) in the greenhouse vegetable fields converted from paddy fields. Correlation analysis showed that O‐alkyl C was significantly positively related to MWD and the proportion of large soil macroaggregate (>2 mm). This result suggested that soil aggregates become fragile in long‐term vegetable cultivation after conversion from paddy fields, and a large loss of O‐alkyl C might be the main reason for this phenomenon. Highlights: Soil aggregation was significantly decreased in conventional vegetable fields converted from paddy fields.SOC accumulation was closely positively related to soil macroaggregate formation.O‐alkyl C mainly decreased in microaggregates, with the opposite observed for aromatic C, in soil of greenhouse vegetable fields.The large loss of O‐alkyl C may explain the degradation of soil aggregates. [ABSTRACT FROM AUTHOR]

Agriculture in the boreal and Arctic regions is perceived as marginal, low intensity and inadequate to satisfy the needs of local communities, but another perspective is that northern agriculture has untapped potential to increase the local supply of food and even contribute to the global food system. Policies across northern jurisdictions target the expansion and intensification of agriculture, contextualized for the diverse social settings and market foci in the north. However, the rapid pace of climate change means that traditional methods of adapting cropping systems and developing infrastructure and regulations for this region cannot keep up with climate change impacts. Moreover, the anticipated conversion of northern cold-climate natural lands to agriculture risks a loss of up to 76% of the carbon stored in vegetation and soils, leading to further environmental impacts. The sustainable development of northern agriculture requires local solutions supported by locally relevant policies. There is an obvious need for the rapid development of a transdisciplinary, cross-jurisdictional, long-term knowledge development, and dissemination program to best serve food needs and an agricultural economy in the boreal and Arctic regions while minimizing the risks to global climate, northern ecosystems and communities.

Land‐use change is a key factor driving changes in soil organic carbon (SOC) sequestration worldwide. However, the changes in deep (>100 cm depth) SOC stock following land‐use conversion have not been fully elucidated. In this study, to determine the changes in deep SOC stock (to a depth of 400 cm) resulting from conversion of cropland to woodland, shrubland and grassland on the Chinese Loess Plateau, 469 observations from peer‐reviewed publications and original measured data were synthesised. The results were as follows: (a) SOC stock increased significantly at 0–100 and 100–200 cm layers regardless of land‐use conversion types. (b) Carbon loss occurred in the 200–400 cm layers due to land‐use conversion. (c) Changes in SOC stock varied with restoration age, except for conversion of cropland to grassland. Specifically, SOC stock increased with restoration age in the upper 200 cm layers, whereas that in the 200–400 cm layers first increased and then decreased in the middle to later stages under conversion to woodland and shrubland. (d) Initial SOC stock and rainfall zones had significant effects on the changes of deep SOC stock. (e) Furthermore, an accumulation of 1 Mg ha−1 in the upper 100 cm was associated with an approximately 0.45 Mg ha−1 increase in the 100–400 cm soil layers. These results indicate that land‐use conversion, particularly conversion of cropland to woodland, changes deep (>100 cm) SOC stock, and restoration age should be taken into consideration when assessing deep carbon sequestration. [ABSTRACT FROM AUTHOR]

Purpose: Organic manure is beneficial for macro-aggregate formation and soil organic carbon (SOC), but how SOC change in aggregate fractions in time-series is still uncertain. Moreover, greenhouse systems converted from cereal fields quickly faced soil degradation. Thus, the role of organic manure here should be discussed. The main objectives of this study were to determine the change of SOC fractions in bulk soil and aggregation level affected by long-term organic manure application. Materials and methods: Using 13C solid-state nuclear magnetic resonance (NMR) spectroscopy, we investigated the SOC and its fraction changes within bulk soil and aggregate fractions under 1-year, 9-year, and 14-year organic greenhouse vegetable cultivation, and we also analysed the soil properties of rice-wheat rotation (RWR) fields as the control. Soil aggregate samples were wet sieved into large macro-aggregates (> 2 mm), small macro-aggregates (2–0.25 mm), micro-aggregates (0.053–0.25 mm), and silt and clay particles (<0.053 mm). Results and discussion: The proportion of large macro-aggregates increased significantly (P ≤ 0.05) from 1.68 to 7.76% during the 14-year organic cultivation period. Similar trends could also be found in SOC and its fractions. Specifically, the O-alkyl C increased fastest by 14.5 g kg−1 over these years, but its proportion decreased. The change in aggregate associated C was concentrated on large macro-aggregates and micro-aggregates. Pearson's correlation suggested that there was a non-significant relation between SOC and soil aggregation, while the soil aggregate associated C had a significantly positive relationship with SOC and its fraction amounts. However, the proportion of O-alkyl C was less; the aggregation associated C was higher. Conclusions: This study has shown the different effects of SOC fractions on soil aggregation and aggregate associated C in organic greenhouse vegetable fields. The stable C fractions might show contribution in soil aggregate associated C than active C fractions. It might improve our knowledge about how organic manure may influence soil aggregation by increasing SOC after a long-term greenhouse vegetable plantation. [ABSTRACT FROM AUTHOR]

This paper analyses the extent to which local land supply is the result of strategic interaction among nearby local governments. In a setting of limited tax instruments to raise revenues and interjurisdictional competition for mobile residents, municipal authorities are provided with the economic incentives to convert land from rural to urban uses, hence promoting urban growth. Using data on a large sample of Spanish municipalities for the period 2003–11 and a modified Cournot-style competition model, we report evidence in support of this hypothesis. The results suggest that local incumbents do not make policy decisions in isolation, and reaction functions arise because the mobile tax base reacts to the regulatory measures that modify land uses in each municipality. [ABSTRACT FROM AUTHOR]

Forestry has long been considered an effective means of restoring degraded drylands worldwide. Often, afforestation in such lands relies on the establishment of runoff harvesting systems that are formed as contour bench terraces on hillslopes, increasing water availability for the planted trees and shrubs. The construction of terraces requires intensive earthworks by heavy machinery. This study assessed the long-term (>10 yrs) effects of forestry-related land-use change on soil properties and herbaceous vegetation in 16-year-old and 12-year-old afforestation sites (established in 2005 and 2009), and in nearby control ("natural") areas in the semi-arid northern Negev, Israel. Mean herbaceous vegetation height in the 2005 afforestation sites (12.1 cm) was significantly (P = 0.0009) and 23% greater than in the control areas (9.8 cm), whereas in the 2009 afforestation sites (6.2 cm) it was 37% lesser than in the control areas. Mean herbaceous vegetation aboveground biomass was similar in the 2005 afforestation (0.39 Mg ha−1) and control areas (0.38 Mg ha−1), and almost significantly (P = 0.0510) and twofold greater than in the 2009 afforestation sites (0.19 Mg ha−1). The effect of hillslope aspect on these variables was substantial; their mean values were higher in the northern (mesic) hillslopes than in the southern (xeric) hillslopes. Soil samples were obtained from depths of 0–5 and 5–10 cm and physio-chemo-biological properties were assessed in the laboratory. The overall soil quality – as calculated by two soil quality indices (SQIs), including the generalized SQI (SQI gen) and the minimum dataset SQI (SQI MDS) – was significantly (P < 0.0001 for both indices) and 13–22% greater in the control areas (0.52 and 0.61, respectively) than that in the afforestation treatments (0.44–0.46 and 0.50–0.51, respectively). These results are generally attributed to the removal of soil's A-horizon during earthworks, and the exposure of the underlying B-horizon. The similar SQI values of both hillslope aspects, as well as of both soil depths, indicate the generally degraded state of the entire region. In conclusion, while contour bench terracing may facilitate the recovery of herbacaeous vegetation to some extent, the effectiveness of this practice for soil restoration is questionable. Overall, insights of this study demonstrate a caveat that converting natural drylands to forestry systems may not yield sufficient ecological benefits, and therefore should be implemented with caution. • Afforestation seems to increase productivity of herbaceous vegetation. • However, afforestation caused the decrease in several soil functions. • Soil quality indices in afforestation sites were lower than in control sites. [ABSTRACT FROM AUTHOR]

Under climate change and local and global food security pressures conversion to agricultural lands on Podzols developed under boreal forests is accelerating across the global north. After conversion Podzols, acid and sandy, are infertile requiring significant management to allow economic production. Biochar, while less useful on fertile soils, may accelerate fertility gains on such marginal lands; it is already considered or land-applied by local farmers, under minimal guidance. A multi-year experiment assessed the utility of single or split application of biochar (BC), and of BC doses, for beet yields and nutrient uptake on newly converted Podzols. Time and rate-dependent progression of yields, macro- and micro-nutrients uptake, all parameters identified of interest by northern farmers, were evaluated. Kiln-derived hardwood biochar was added at 0, 10, 20, 40 or 80 Mg BC-C ha−1 (BC 0 to 80) either as single or as double application. Beet yields and elemental compositions were assessed over 4 years after biochar application. Work was done on a private farm in Labrador, Canada, under a scenario relevant to the boreal north. BC 0 could not sustain significant crop growth, suggesting that post-conversion mineralization of residual soil organic matter cannot support plant growth. In the first one to three years after application of biochar yields increased above the control, but statistically independent of application rates. A statistically significant positive biochar-rate to yield dependency was verifiable only in year 4. Nevertheless, biochar's positive effect on yields declined with time after application: e.g., BC 10 matched BC 0 yields in year 4. For the first three years, root nitrogen (N) concentrations were inversely correlated to yields and plant N% declined with biochar rate. In year 4 plant N% was directly correlated to plant biomass. In general, partitioning of nutrients between beet leaves and roots was not discernibly affected by the rate of biochar; an exception was boron whose preferential accumulation in leaves was directly related to the rate of biochar, indicating a role for the biochar for its mobilization. Biochar had an immediate positive effect on the beet yields and affected plant stoichiometry. Initially this was independent of the biochar rate. Biochar's utility declined with time at a rate inversely related to its application rate. Biochar is a recommendable fertility management tool for infertile, newly converted boreal Podzols; rates in the range of 10 Mg BC-C ha-1 may be repeated annually or every few years as practically feasible. Long term utilization requires further monitoring of micronutrients availability and uptake to inform any necessary management adjustments. Fertilizer management must consider the time since biochar's addition to soil. • Unmanaged Podzols on freshly converted boreal forest are infertile. • Biochar addition increases beet yield and yield quality, initially rate-independent. • A rate-dependent impact of biochar on yields and yield quality was noted in year 4. • Biochar's benefit fades over time at a rate inverse to its application rate. • Repeated, small biochar doses are recommendable over large single applications. [ABSTRACT FROM AUTHOR]

Population growth, economic globalization and the launch of market economy instruments have become the main triggers for processes related to the anthropogenization of space. According to Organisation for Economic Co-operation and Development (OECD) statistics, the developed area indication tripled in the last 25 years. Humans keep appropriating more natural and semi-natural areas, which entails specific social, economic and environmental consequences. Provisions in some countries’ laws and some economic factors encourage investors to engage in urbanization. The authors of this study noticed a research gap in the analysis of suburban areas in this topic. Our research aimed to analyze the conversion of plots of land used for agricultural purposes into urbanized land in the city’s suburban zone, in areas of high landscape and natural value. We focused on the analysis of geodetic and legal divisions of plots of land and analyzed the conditions of plots of land “ex ante” and “ex post” and the changes in their values. To achieve the research objective, we used Corine Land Cover (CLC) data for various time intervals, orthophotomaps (using the Web Map Service browsing service compliant with Open Geospatial Consortium standards), cadastral data, administrative decisions, data from the real estate market, spatial analyses and statistical modeling (linear, non-linear and stepwise regression). In general, the CLC data resolution enables analysis at regional or national levels. We used them innovatively at the local level because CLC data allowed us to notice the development of the area over time. Detailed research confirmed that, in the studied area, the conversion of agricultural land into developed areas results from economic factors. The division procedure increases the plot value by about 10%. However, the effects of uncontrolled urbanization, which we are currently dealing with, generate long term social and economic losses, difficulties in the labour market and may become a barrier to development.

Converting natural forests to plantations would markedly change soil physiochemical and biological properties, as a consequence of changing plant vegetative coverage and management practices. However, the effects of such land-use change on the soil nutrient pools and related enzymes activities still remain unclear. The aim of this study was to explore the effects of conversion from natural evergreen broadleaf forests to Moso bamboo plantations on the pool sizes and forms of soil N, P and K, microbial biomass, and nutrient cycling related enzyme activities. Soil samples from four adjacent evergreen broadleaf forest-Moso bamboo plantation pairs were collected from a subtropical region in Zhejiang Province, China. The soil organic C (SOC), total N (TN), total P (TP) and total K (TK) concentrations and stocks and different N, P and K forms were measured, and the microbial biomass C (MBC), microbial biomass N (MBN), microbial biomass P (MBP) and four soil enzymes (protease, urease, acid phosphatase and catalase) were determined. The results showed that converting broadleaf forests to Moso bamboo plantations decreased the concentration and stock of SOC but increased those of TK in both soil layers (0–20 and 20–40 cm), and such land-use change increased the concentration and stock of TN and TP only in the 0–20 cm soil layer ( P  < 0.05). This land-use conversion increased the concentrations of NH 4 + -N, NO 3 − -N, resin-P i , NaHCO 3 -P i , NaOH-P i , HCl-P i , available K and slowly available K, but decreased the concentrations of water-soluble organic nitrogen (WSON), NaHCO 3 -P o and NaOH-P o ( P  < 0.05). Further, this land-use change decreased the microbial biomass and activities of protease, urease, acid phosphatase and catalase ( P  < 0.05). In addition, the acid phosphatase activity correlated positively with the concentrations of MBP and NaHCO 3 -P o , and the activities of urease and protease correlated positively with the concentrations of MBN and WSON ( P  < 0.01). To conclude, converting natural broadleaf forests to Moso bamboo plantations had positive effects on soil inorganic N, P and K pools, and negative effects on soil organic N and P pools, and on N- and P-cycling related enzyme activities. Therefore, management practices that increase organic nutrient pools and microbial activity are needed to be developed to mitigate the depletion of organic nutrient pools after the land-use conversion. [ABSTRACT FROM AUTHOR]

Rice paddy conversion to vegetable production is a common agricultural practice driven by economic benefits and shifting diets. However, little is known on the initial effects of this land-use conversion on net ecosystem carbon budget (NECB) and greenhouse gas (GHG) balance. Annual NECB and emissions of CH 4 and N 2 O were measured from a native double rice cropping system (Rice) and a vegetable field recently converted from rice paddy (Veg) under no nitrogen (N) fertilization (Rice-N 0 and Veg-N 0 ) and conventional N fertilization (Rice-N + and Veg-N + ) during the initial four years upon conversion in subtropical China. Land-use conversion from rice to vegetable cultivation led to substantial C losses (2.6 to 4.5 Mg C ha −1  yr −1 ), resulting from strongly reduced C input by 44–52% and increased soil organic matter mineralization by 46–59% relative to Rice. The magnitude of C losses from Veg was highest in the first year upon conversion, and showed a decreasing trend over time. N fertilization shifted rice paddy from a slight C source in Rice-N 0 (−1.0 Mg C ha −1  yr −1 ) to a significant C sink in Rice-N + (1.1 Mg C ha −1  yr −1 ) and alleviated the impact of land-use conversion on C loss via increased C input from higher crop productivity. Land-use conversion greatly increased the global warming potential (GWP) from Veg by 116–395% relative to Rice in the first year, primarily due to increased C losses and N 2 O emission outweighing the decreased CH 4 emission. However, the GWP did not show obvious difference between Rice and Veg in the following years. N fertilization and land-use conversion interactively increased GWP in the first year via increased N 2 O production. Concluding, NECB and GHG emissions in the first year after conversion are crucial and should be considered when evaluating the environmental consequences of land-use conversion. [ABSTRACT FROM AUTHOR]

Abstract: Habitat loss is one of the greatest threats to biodiversity, exerting negative effects on the ecological viability of natural vegetation remnants. The south Brazilian grasslands belong to one of the largest temperate grassland regions in the world, but have lost 50% of their natural extent in the past 35 years. To date, there is no empirical evidence for the effects of habitat loss on these grasslands' biological diversity, undermining their conservation. Using data from a large‐scale biodiversity survey, we asked if local plant communities respond to levels of habitat loss representative of the entire region (≤50%). Vegetation in grassland remnants was sampled in 24 landscapes at three localities each, using nine plots per locality. To investigate whether species losses were a consequence of stochastic or nonrandom local extinctions and whether plant communities became more homogenized, we evaluated species richness, beta‐diversity components (spatial turnover and nestedness), and phylogenetic diversity, in respect to landscape change. In part of the landscapes, arthropods were sampled to investigate if loss of plant diversity had a cascading effect on other trophic levels. We evaluated generic richness of ants, an omnivore group with high levels of plant associations, in respect to a plant community's phylogenetic diversity. Local plant communities in landscapes with less grassland cover had fewer species, less spatial turnover, increased nestedness and lower phylogenetic diversity. Our results suggest that the observed species loss can be linked to taxonomic homogenization and is nonrandom, decreasing evolutionary diversity within the community. Furthermore, ant richness declined by 50% in plant communities with the lowest phylogenetic diversity, suggesting that effects of habitat loss propagate to higher trophic levels. Policy implications. We conclude that the biological diversity of south Brazilian grasslands, at the producer and consumer level, is at risk under the current rate of land‐use conversion, even at habitat losses below 50%. To avoid substantial biodiversity loss, conservation and more restrictive policies for conversion of native grasslands to different land uses in South Brazil are urgently needed. [ABSTRACT FROM AUTHOR]

Land-use conversion affects the soil community and microbial abundance, which are essential dynamic indicators of soil quality and sustainability. However, little to no work has been performed to analyse the impact from different land-use histories (i.e. fallow, tea, rice, banana, and maize) on the microbial abundance and diversity in the soil of sacha inchi (Plukenetia volubilis L.). Real-time quantitative PCR (qPCR) was performed to quantify soil bacterial and fungal abundance. Denaturing gradient gel electrophoresis (DGGE) combined with cloning and sequencing was used to assess the microbial communities. Our results showed that the bacterial and fungal abundance in fallow land-use conversion soils was significantly lower than that in the other four land-use conversion soils (tea, rice, banana, and maize). Moreover, the highest abundance of bacteria and fungi was detected in the soils converted from maize to sacha inchicultivation. In addition, canonical correspondence analysis (CCA) showed that the total N and pH were significantly related to bacterial and fungal community structures. These results suggest that land-use conversion from maize fields to sacha inchi farms is an effective way to maintain the soil microbial quantity and hence the sustainability of the soil. [ABSTRACT FROM AUTHOR]

Context Methods for measuring restoration success that include functional connectivity between species' populations are rare in landscape ecology and restoration practices. We developed an approach that analyzes connectivity between populations of target species and their dispersal probabilities to assess restoration success based on easily accessible input data. Applying this method to landscape development scenarios can help optimize restoration planning. Objectives We developed an assessment for restoration success and restoration planning based on functional connectivity between species' populations and spatially explicit scenarios. The method was used in a case study to test its applicability. Methods Based on data on available habitat, species' occurrence and dispersal ranges, connectivity metrics and dispersal probabilities for target species are calculated using the software Conefor Sensinode. The metrics are calculated for scenarios that reflect possible changes in the landscape to provide a basis for future restoration planning. We applied this approach to floodplain meadows along the Upper Rhine for four plant species and three future scenarios. Results In the case study, habitats of the target species were poorly connected. Peucedanum officinale and Sanguisorba officinalis were more successful in recolonizing new habitats than Iris spuria and Serratula tinctoria. The scenarios showed that restoration of species-rich grassland was beneficial for dispersal of the target species. As expected in the agriculturally dominated study area, restoration of former arable land significantly increased dispersal probabilities. Conclusions In the case study, the developed approach was easily applicable and provided reasonable results. Its implementation will be helpful in decision-making for future restoration planning. [ABSTRACT FROM AUTHOR]

Urbanization has the potential to induce major changes in freshwater systems. Expected increases in human populations will likely amplify these changes and lead to the overall degradation of habitat quality within these systems. Such habitat alterations may function as stressors that can affect glucocorticoid stress hormones in freshwater vertebrates. Examining changes in physiological stress may provide early warning indicators of environmental threats and provide insights into the sub-lethal effects of habitat degradation. The threatened, obligate aquatic, Jollyville Plateau salamander ( Eurycea tonkawae ) is found in urbanized and rural catchments within central Texas and has experienced population declines in heavily urbanized areas. We tested the prediction that salamanders from urbanized sites would have different levels of baseline corticosterone (CORT) and muted or no stress responsiveness (to an external stressor, agitation) compared to salamanders from rural sites. We collected water-borne hormones to measure baseline CORT release rates ( n = 3 years) and stress responsiveness ( n = 2 years) in salamanders inhabiting urbanized and rural sites. We also measured “background” CORT from stream water alone at each visit. For the first two years we found that baseline CORT was higher in urbanized sites but not in the third year. Across years and populations, salamanders showed stress responsiveness, suggesting that, even if physiological stress is higher in urbanized areas, it has not resulted in the impairment of the hypothalamic–pituitary–interrenal axis. Background CORT was higher in urban than in rural streams and was positively correlated with mean baseline CORT of salamanders across populations and years. Our results contribute to the goal of finding early warning indicators of environmental threats by demonstrating a relationship between urbanization and the physiological status of E. tonkawae , using a rapid, non-invasive measure of stress. [ABSTRACT FROM AUTHOR]

Increasing demand of commercial markets for tea products is driving the conversion from rice paddies to tea plantations in subtropical China. So far, however, little is known on how this land-use change, along with the age of plantation establishment, will affect the fluxes of greenhouse gases (GHG) methane (CH 4 ) and nitrous oxide (N 2 O) and the air-pollutant nitric oxide (NO). Thus, we measured CH 4 , N 2 O and NO fluxes over an entire year from two tea plantations (one- and five-year-old plantations) and a native rice-fallow system under two system-specific nitrogen fertilizer options. On an annual scale, comparable or higher GHG emissions were measured for tea plantations as compared to the rice-fallow system. Besides the pollution swapping from CH 4 being the dominating GHG in rice paddies to N 2 O in tea plantations, annual NO emissions increased significantly. Annual direct emission factors of N 2 O and NO in tea plantations were 2.47–5.80% and 2.00–3.99%, respectively, significantly higher than in the rice-fallow system (N 2 O: 1.05–2.05%; NO: 0.033–0.051%). Differences in N fertilizer inputs and soil environmental conditions (e.g., soil water regime, pH and organic carbon) due to contrasting managements of these systems and their interactions are clearly driving the stimulation of N 2 O and NO emissions and contributing to the significant CH 4 reductions. Furthermore, we observed that increasing tea stand age, particularly under organic fertilization, further stimulated N 2 O and NO emissions that varied significantly intra-annually. Nevertheless, the higher N 2 O and NO emissions of tea plantations and the increasing emission strength with stand age deserve further research attention and consideration for future land-use conversions. [ABSTRACT FROM AUTHOR]

In this study, we compared the CH 4 and N 2 O fluxes from a tidal brackish Cyperus malaccensis marsh ecosystem and nearby shrimp ponds, converted from C. malaccensis marsh in the last 3–4 years, in the Min River estuary of southeast China over the aquaculture period of the year. Significant differences in CH 4 and N 2 O fluxes were observed in space (between brackish marsh and shrimp ponds) and in time (between sampling occasions that were distributed over the aquaculture period). CH 4 fluxes from the shrimp ponds were on an average 10-fold higher than from the brackish marsh. N 2 O emissions, on the other hand, were lower from the shrimp pond (25% of the emissions from the brackish marsh). Accessory data indicates that these patterns were primarily linked to water level variability and temperature (all fluxes), sediment porewater sulfate concentrations (CH 4 flux) and total nitrogen concentrations (N 2 O flux). Our research demonstrates that the coastal marsh ecosystem converted to aquaculture ponds considerably alter emissions of CH 4 and N 2 O and provides input to the global discussion on how to account for emissions from various types of flooded land in greenhouse gas inventories. [ABSTRACT FROM AUTHOR]

Aim Agricultural intensification and urbanization are important drivers of biodiversity change in Europe. Different aspects of bee community diversity vary in their sensitivity to these pressures, as well as independently influencing ecosystem service provision (pollination). To obtain a more comprehensive understanding of human impacts on bee diversity across Europe, we assess multiple, complementary indices of diversity. Location One Thousand four hundred and forty six sites across Europe. Methods We collated data on bee occurrence and abundance from the published literature and supplemented them with the PREDICTS database. Using Rao's Quadratic Entropy, we assessed how species, functional and phylogenetic diversity of 1,446 bee communities respond to land-use characteristics including land-use class, cropland intensity, human population density and distance to roads. We combined these models with statistically downscaled estimates of land use in 2005 to estimate and map-at a scale of approximately 1 km2-the losses in diversity relative to semi-natural/natural baseline (the predicted diversity of an uninhabited grid square, consisting only of semi-natural/natural vegetation). Results We show that-relative to the predicted local diversity in uninhabited semi-natural/natural habitat-half of all EU27 countries have lost over 10% of their average local species diversity and two-thirds of countries have lost over 5% of their average local functional and phylogenetic diversity. All diversity measures were generally lower in pasture and higher-intensity cropland than in semi-natural/natural vegetation, but facets of diversity showed less consistent responses to human population density. These differences have led to marked spatial mismatches in losses: losses in phylogenetic diversity were in some areas almost 20 percentage points (pp.) more severe than losses in species diversity, but in other areas losses were almost 40 pp. less severe. Main conclusions These results highlight the importance of exploring multiple measures of diversity when prioritizing and evaluating conservation actions, as species-diverse assemblages may be phylogenetically and functionally impoverished, potentially threatening pollination service provision. [ABSTRACT FROM AUTHOR]

Land-use/vegetation is an essential variable on controlling the heterogeneities and distribution pattern of soil water content (SWC). Along with large-scale re-vegetation in arid and semi-arid areas, the variations of SWC ascribed to the land-use conversion have been considered as an important factor to assess the re-vegetation efforts. In this study, soil water data at the depth of 0–300 cm were obtained by field observation in two eco-hydrologic zones in Loess Plateau of China. The mean annual precipitation was 350–400 mm (zone-A) and 500–550 mm (zone-B), respectively. The differences in SWC were analyzed among different land-use types; and the SWC in different restoration years was also discussed using the method of space replacing time. Results indicated that (1) the differences in SWC between the two zones were lower in re-vegetated lands (2.76%, forestland and 4.22%, for shrub land) than in abandoned farmland (5.85%). The differences in re-vegetated lands diminished gradually as the soil depth (0–300 cm) increased, whereas the abandoned farmland represented an opposite trend. (2) Although the variation trends of SWC in abandoned farmland of the two zones were different as the restoration years increased, the differences in SWC between abandoned farmland and native grassland both diminished gradually. This meant the soil water deficit relative to native grassland would be alleviated as the progress of abandoned farmland. (3) As the restoration years increased, the differences in SWC between re-vegetated lands and native grassland increased gradually because of the continuous decrease of SWC in re-vegetated lands. The consequence will be that the soil water deficit in the re-vegetation lands is aggravated continually. From the perspective of soil water restoration and conservation in semi-arid areas, the abandoned farmland should be a more reasonable method than re-vegetated lands covered with introduced plants. [ABSTRACT FROM AUTHOR]

Afforestation on the Chinese Loess Plateau (CLP) has been extensively implemented by the central government over the past decades to control soil erosion. The conversion of agricultural land to forest, however, has led to decreases in soil-water storage (SWS), which may in turn limit tree growth and threaten the health of ecosystems in the region. This study estimated the regional patterns of losses of soil water (ΔSWS) following conversions across the CLP. Soil-water content at 0-5.0 m was measured in 169 forests on the plateau, and the initial preafforestation SWS at each sample site was then estimated using stepwise regression. The mean ΔSWS in the 1.0- to 5.0-m profile across the study area was 203.7 mm, with an estimated annual average ΔSWS rate of 16.2 mm/year. ΔSWS and its main contributing factors varied amongst 3 rainfall zones. ΔSWS generally increased with mean annual precipitation (MAP). ΔSWS depended primarily on tree age in the >550 mm MAP zone and on slope gradient and initial SWS in the <450 mm MAP zone. This result suggested that the vegetation might be more important than soil or topographic properties for estimating ΔSWS following the conversion of farmland in the wettest area of the CLP. Our study also suggests that MAP, tree age, slope gradient, and initial SWS have important effects on ΔSWS, which vary with rainfall. Understanding the regional hydrological effects of afforestation is necessary for the efficient management of soil-water resources on the CLP and in other water-limited regions. [ABSTRACT FROM AUTHOR]

Ammonia oxidation, the conversion of ammonium (NH 4 + -N) to nitrite (NO 2 − -N), is the critical step of nitrification and performed by ammonia-oxidizing archaea (AOA) and bacteria (AOB). However, the effects of land-use conversion and fertilization on the AOA and AOB are not well documented, and the contribution of these two groups to soil ammonia oxidation is still debatable. This study aimed to explore how land-use conversion from rice paddies (RP) to citrus orchards (OR) and fertilization affect the abundance and communities of AOA and AOB, and whether AOA and AOB were correlated to ammonia oxidation. The potential ammonia oxidation (PAO) was measured by chlorate inhibition method, and the abundance and communities of AOA and AOB were quantified using quantitative real-time polymerase chain reaction (qPCR), terminal restriction fragment length polymorphism (T-RFLP) and cloning and sequence analysis. Land-use conversion from RP to OR tended to increase PAO, whereas fertilization increased PAO only in the OR. qPCR results demonstrated that land-use conversion significantly increased AOA abundance, but failed to affect the AOB abundance. The AOA abundance was increased in the OR but decreased in the RP after fertilization, whereas fertilization distinctly stimulated AOB abundance in the OR and RP. T-RFLP analysis showed that the communities of AOA and AOB were significantly changed after land-use conversion. Meanwhile, fertilization significantly affected the communities of AOB both in the OR and RP and only affected the communities of AOA in the OR. Phylogenetic analyses of amo A genes showed that group 1.1 a like lineage predominated archaea ammonia oxidizers in the acidic red soil, while all AOB clones were belonged to the Nitrosospira . Besides, soil ammonia oxidation was positively correlated to AOA and AOB abundance both in the OR and RP. Our findings imply that land-use conversion and fertilization could potentially alter the ammonia oxidation by regulating the growth of AOA and AOB in this acidic red soil. [ABSTRACT FROM AUTHOR]

Changes in land-uses and fertilization are important factors regulating methane (CH) emissions from paddy soils. However, the responses of soil CH emissions to these factors and the underlying mechanisms remain unclear. The objective of this study was to explore the effects of land-use conversion from paddies to orchards and fertilization on soil CH fluxes, and the abundance and community compositions of methanogens and methanotrophs. Soil CH fluxes were quantified by static chamber and gas chromatography technology. Abundance and community structures of methanogens and methanotrophs (based on mcrA and pmoA genes, respectively) were determined by quantitative real-time PCR (qPCR), and terminal restriction fragment length polymorphism (TRFLP), cloning and sequence analysis, respectively. Results showed that land-use conversion from paddies to orchards dramatically decreased soil CH fluxes, whereas fertilization did not distinctly affect soil CH fluxes. Furthermore, abundance of methanogens and methanotrophs were decreased after converting paddies to orchards. Fertilization decreased the abundance of these microorganisms, but the values were not statistically significant. Moreover, land-use conversion had fatal effects on some members of the methanogenic archaea ( Methanoregula and Methanosaeta), increased type II methanotrophs ( Methylocystis and Methylosinus), and decreased type I methanotrophs ( Methylobacter and Methylococcus). However, fertilization could only significantly affect type I methanotrophs in the orchard plots. In addition, CH fluxes from paddy soils were positively correlated with soil dissolved organic carbon contents and methanogens abundance, whereas CH fluxes in orchard plots were negatively related to methanotroph abundance. Therefore, our results suggested that land-use conversion from paddies to orchards could change the abundance and community compositions of methanogens and methanotrophs, and ultimately alter the soil CH fluxes. Overall, our study shed insight on the underlying mechanisms of how land-use conversion from paddies to orchards decreased CH emissions. [ABSTRACT FROM AUTHOR]

Various environmental and socioeconomic issues have been attributed to land-use changes, and therefore, the underlying mechanisms merit investigation and quantification. This study assesses a comprehensive series of land-use conversions that were implemented over a recent 12-year period in the province of Alberta, Canada, where rapid economic and population growth has occurred. Spatial autocorrelation models are applied to identify the comprehensive effects of environmental and socioeconomic factors in each conversion case. The empirical results show that the impacts of key environmental and socioeconomic factors varied in intensity depending on the type of land-use conversion involved. Overall, land suitability for agricultural uses, road density, elevation, and population growth were found to be significant predictors of land-use changes. High land suitability, low elevation, and moderate road density were associated with land conversion for agricultural purposes. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate influences of six-year past application rates of nitrogen and a catch crop, sweet corn (Zea maysL. ssp.SaccharataSturt), on soil microbial community and diversity in a greenhouse-based intensive vegetable soil in eastern China. Soil electrical conductivity, pH, mineral nitrogen, phospholipid fatty acids (PLFA) profiles and carbon sourceutilizationpatterns under five annually past nitrogen rates (0, 348, 522, 696 and 870 kg nitrogen ha−1) were evaluated after the establishment of sweet corn during 1–1.5-month fallow period over three-year tomato/cucumber/celery rotations. The past nitrogen application rates exerted significant effects on soil electrical conductivity, pH, nitrate-nitrogen, ammonium-nitrogen and carbon source utilization patterns, but not on PLFAs profiles. The sweet corn had a significant effect on soil chemical properties, total and actinobacterial PLFAs, but not on carbon source utilization patterns. Soil electrical conductivity, nitrate-nitrogen and the total PLFAs decreased whilst soil organic carbon, pH and the actinobacterial PLFAs increased after the establishment of sweet corn. Soil microbial functional diversity from carbon source utilization patterns and actinobacterial PLFAs were greatest after the establishment of sweet corn at a 60% of the conventional nitrogen rate (i.e. 522 kg nitrogen ha−1). Soil electrical conductivity and ammonium-nitrogen were two key factors to determine carbon source utilization patterns, whilst soil pH was the key factor to determine PLFAs profiles. A combination of the catch crop sweet corn during summer fallow and a 60% of the conventional nitrogen rate is a sustainable pathway of utilizing greenhouse-based intensive vegetable soils in eastern China. [ABSTRACT FROM AUTHOR]

• Soil structure became stable after natural restoration. • Warming exerted less effect on the soil structure in restored land. • Warming weaken the protection of P fractions by macroaggregates under natural restoration. • The release risk of available P in smaller-sized aggregates needs to be focused. • Biological factors in P-cycling model help gauge P-fraction climate-change responses. The responses of soil aggregation and aggregate-associated phosphorus (P) fractions under natural restoration to climate warming remain unclear. Here, we conducted an eight-year mesocosm experiment wherein farmland soil from a colder site was transplanted to a warmer site to simulate climate warming and established continuous soybean cultivation and natural restoration treatments at each site. We investigated soil aggregate stability and the associated P fractions and soil properties under two land-use systems in a warming climate. Our results revealed that natural restoration significantly increased macroaggregates and macroaggregate-associated NaHCO 3 -Pi, NaOH-Po, and TP, but warming impeded the increases of these P fractions without changing soil aggregation. Although TP within microaggregates and the silt and clay fractions remained consistent across treatments, warming resulted in higher NaHCO 3 -Pi concentrations in both fractions and lower NaHCO 3 -Po and NaOH-Po within microaggregates in restored land. Bacterial community and alkaline phosphatase activity may be responsible for organic P mineralization within microaggregates. The enrichment of NaHCO 3 -Pi in smaller-sized aggregates and non-aggregate particles with warming likely increased the risk for P loss. Fungal and bacterial phospholipid fatty acid explained the most variation in the P fractions within macroaggregates and microaggregates, respectively, suggesting that biological processes are involved in determining P distribution. Our study indicates that the distribution of P fractions in differently sized aggregates during natural restoration can be significantly influenced by warming and highlights that incorporating the responses of soil microorganisms and enzymes will improve our understanding of the P cycling in a warming climate. [ABSTRACT FROM AUTHOR]

In this study, the CO2 and CH4 fluxes in the first year after land use conversion from paddy rice to vegetables were measured by static opaque chamber and gas-chromatograph (GC) method to investigate the land conversion effects on soil CO2 and CH4 emissions. Our results showed that the differences in CO2 fluxes depended on the vegetable types, growing status and seasons. The CO2 flux from the vegetable field was greater than that from the paddy rice field when cowpea was planted, but was lower when pepper was planted. The CH4 flux significantly decreased from 6.96 mg C • m-2 • h-1 to -0.004 mg C • m-2 • h-1 with the land use conversion from rice to vegetables. The net carbon absorption (CO2 + CH4) of the vegetable fields was 543 kg C • hm-2, significantly lower than that (3641 kg C • hm-2) of the rice paddies. However, no significant difference was found in their global warming impact. In addition, soil carbon content increased in vegetable fields compared to the paddy rice fields after a year of conversion, especially in the 10-20 cm soil layer. [ABSTRACT FROM AUTHOR]

In irrigated agricultural landscapes, land-use conversion may have landscape-level social, hydrological, and ecological effects. We used geographic information systems (GIS) and interviews to analyze development effects on irrigation in the Henry's Fork Watershed, Idaho. Farmers developed irrigation there in the 19th century, and incidental recharge from canal seepage and flood irrigation raised groundwater levels and expanded wetlands. Cohesive culture in agricultural communities sustained irrigation systems until amenity-driven demographic shifts beginning in the 1970s led to development approved by local governments with land-use planning but no water-management authority. Although only 5% of irrigated land has been converted, development has fragmented irrigated landscapes and made canal-system operation more difficult, potentially reducing groundwater levels, wetland extent, and return flows critical to downstream irrigators and fish and wildlife. We discuss future scenarios, highlighting the need for increased communication among local and state governments regarding land use and water management in irrigated landscapes across the West. [ABSTRACT FROM AUTHOR]

The aim of this study was to better understand the effects of grassland restoration on carbon sequestration at the total carbon stock (plant and soil) scale. The objective of the study was to investigate the temporal carbon sink and sequestration dynamics of grassland ecosystems with five different succession communities, namely, Stipa grandis, Stipa bungeana, Artemisia sacrorum, Thymus mongolicus, and cropland succession in the hilly-gully region of the Loess Plateau, China. Twenty-four research papers were analyzed to form the basis of the subsequent field survey conducted at the Yunwu Observatory for Vegetation Protection and Eco-environment in Ningxia. Following the conversion of cropland to grassland, carbon sequestration values all increased at deeper soil depths of 40-100 cm; carbon stocks within the 0-40 cm profile were largely unchanged. Five time intervals, 0 (cropland) 23, 35, 58, and 78 years yielded carbon stocks of 7.69, 14.58, 16.25, 19.22, and 19.95 kg/m2 at the total carbon stock scale. The main finding indicates that the conversion of cropland to grassland results in significant changes to ecosystem carbon pool properties. This finding has broad implications for the anthropogenic management of terrestrial carbon sequestration at the regional scale. [ABSTRACT FROM AUTHOR]

Soil fertility decline caused by deforestation, soil degradation and low input use has become a primary factor limiting sustainable utilization of soil resources in cocoa agroforestry systems on acid soils in lowland humid Ghana. Changes in and responses of soil physico-chemical properties and soil quality to land-use change was investigated along a chronosequence of farm fields on a Ferric Lixisol in the Ashanti region of Ghana. Soil bulk density increased significantly only in the top 0-10 cm soil layer. Concentrations and stocks of soil organic carbon (SOC) and total N decreased significantly in the top 0-10 and 10-20 cm soil depths. By 30 years after forest conversion, cocoa system had re-accumulated up to 38.8 Mg C ha or 85 % of initial forest carbon stock values. Total porosity (%) decreased significantly in shaded-cocoa fields in comparison with the natural semi-deciduous forest. An assessment of soil deterioration using degradation indices (DIs) revealed that total soil quality (0-20 cm) deteriorated significantly (DI = -60.6) in 3-year-old of cocoa system but improved in 15 and 30-year-old systems. Available P stocks declined consistently while soil exchangeable Ca, K and Mg stocks as well as cation exchange capacity (CEC) and base saturation remained more or less stable with a tendency to improve. The inclusion of leguminous shade trees during early plantation development, development of mechanisms for the integration of cover crops and enhancement of farmer capability in improved farm management are required to maintain high C and nutrient base, minimize soil quality degradation during plantation development phase and sustain long-term productivity. [ABSTRACT FROM AUTHOR]

The process of urbanization is one of the most important dimensions of economic, social and physical changes. It is almost a truism that the planet’s future is an urban one and that the largest and fastest growing cities are in developing countries. Approximately 25 percent of Africa’s population lived in towns and cities in 1975. By the year 2000, due to rural-urban migration and rapid rates of natural increase, 38 percent of the continent’s population lived in urban areas. The proportion is expected to increase to 47 percent by 2015 and to double by 2025, Kenya is not an exception. Rapid urban population growth means an increasing demand for urban land. This land is not available within the city, but in the rural-urban fringe, for various reasons. This is partly due to low land prices, high rents at the core of the cities and legal flexibility in land use planning in the rural-urban fringe. Urban growth is already engulfing the surrounding agricultural lands and small villages. The conversion of agricultural land to residential uses is leading to the rapid transformations in the agricultural production, spatial structure, social structure, land ownership and land market in these areas. This chapter focuses on the responses/actions of the communities within Nairobi rural-urban fringe and how they manoeuvre through the consequences of changes occasioned by land conversions. It used Town council of Karuri as a case study. The chapter is based on qualitative research approaches presents evidence on how subaltern’ actions plays an important role in creating order in an otherwise chaotic situation as a result of ‘poorly planned’ residential development. The subalterns’ actions, as evidenced by their agency, are manifested in community’s contribution and participation in provision of infrastructure and services within the Nairobi’s rural-urban fringe due to inability of formal provision by planning authorities.

Land-use conversion can affect the soil microbial community diversity, soil organic matter and nutrient cycling. In this study, soils within a representative land-use sequence were sampled in a subtropical region of China, including four natural forests, Altingia gracilipes Hemsl. (ALG), Cinnamomum chekiangense Nakai (CIC), Castanopsis fargesii Franch. (CAF), and Tsoongiodendron odorum Chun (TSO), and two plantations, Cunninghamia lanceolata (Lamb.) Hook. (CUL) and a citrus orchard (Citrus reticulata Blanco). The soil microbial diversity was investigated by phospholipid fatty acid (PLFA) analysis, denaturing gradient gel electrophoresis (DGGE) and real-time quantitative polymerase chain reaction (PCR). Results showed that microbial community diversity exhibited distinct patterns among land-use types. After conversion of natural forests to plantations, the amount of PLFA and the number of bacterial 16 S rRNA gene copies were reduced significantly, as well as the number of DGGE bands. The average quantity of PLFA was lower by 31% in the CUL plantation and 57% in the citrus orchard, respectively, than in natural forests. Simultaneously, the average copy numbers of the bacterial 16 S rRNA gene were significantly decreased from 8.1 × 1010 g−1 dry weight (DW) in natural forest to 4.9 × 1010 g−1 DW in CUL plantation, and 3.1 × 1010 g−1 DW in the citrus orchard. Such negative responses of soil microbes to conversion of natural forests to plantations could mainly result from decreases in soil organic carbon and necessary elements for growth during land-use conversion, as revealed by statistical analysis. Our results suggested that the soil microbial diversity was indirectly influenced by land-use types in the mid-subtropical mountainous area of southern China. Changes in the amount of litterfall and the soil nutrient status that resulted from land-use conversion drove these indirect changes. Furthermore, deliberate management brought negative effects on soil microbes, which is not beneficial to the sustainability of the ecosystem. [ABSTRACT FROM PUBLISHER]

Aims Ecosystem carbon models often require accurate net ecosystem exchange of CO2 (NEE) light-response parameters, which can be derived from the Michaelis–Menten equation. These parameters include maximum net ecosystem exchange (NEEmax), apparent quantum use efficiency (α) and daytime ecosystem respiration rate (Re). However, little is known about the effects of land conversion between steppe and cropland on these parameters, especially in semi-arid regions. To understand how these parameters vary in responses to biotic and abiotic factors under land conversions, seasonal variation of light-response parameters were evaluated for a steppe and a cropland of Inner Mongolia, China, during three consecutive years (2006–08) with different precipitation amounts. Methods NEE was measured over a steppe and a cropland in Duolun, Inner Mongolia, China, using the eddy covariance technique, and NEE light-response parameters (NEEmax, α and Re) were derived using the Michaelis–Menten model. Biophysical regulations of these parameters were evaluated using a stepwise regression analysis. Important Findings The maximum absolute values of NEEmax occurred in the meteorological regimes of 15°C ≤ Ta < 25°C, vapor pressure deficit (VPD) < 1 KPa and 0.21 m3 m−3 ≤ volumetric soil water content at 10 cm (SWC) < 0.28 m3 m−3 for both the steppe and the cropland ecosystems. The variations of α and Re showed no regular variation pattern in different Tair, VPD and SWC regimes. Under the same regime of Tair, VPD and SWC, the cropland had higher absolute values of NEEmax than the steppe. Canopy conductance and leaf area index (LAI) were dominant drivers for variations in NEE light-response parameters of the steppe and the cropland. The seasonal variation of NEE light-response parameters followed the variation of LAI for two ecosystems. The peak values of all light-response parameters for the steppe and the cropland occurred from July to August. The values of NEE light-response parameters (NEEmax, α and Re) were lower in the driest year (2007). Seasonally averaged NEE light-response parameters for the cropland surpassed those for the steppe. Land conversion from steppe to cropland enhanced NEE light-response parameters during the plant growing period. These results will have significant implications for improving the models on regional NEE variation under climate change and land-use change scenarios. [ABSTRACT FROM PUBLISHER]

We have evaluated the global warming impact of palm oil production in a model that simulates the operations of a typical palm oil mill that processes fruit from a nucleus estate and outgrowers. It estimates carbon sequestration in the crop and in mill products and by-products, and balances this against the major sources of greenhouse gases (GHGs), all converted to carbon dioxide equivalents (CO2-e) over the 25-year lifespan of the crop. The model shows that most carbon sequestration occurs in the standing crop, with smaller amounts in mill products and by-products. Land-use conversion plays a dominant role in the GHG budget, with planting of oil palm after logged forest or rubber leading to a net loss of carbon, and to a net gain following grassland. In the default oil-palm-to-oil-palm case the carbon lost from cleared palms is balanced by sequestration in the current crop. Methane from mill effluent and nitrous oxide from N fertilizers are the next most important emission sources. The default replant case gives net emissions of O.86t CO2-e per t crude palm oil, but these can be reduced to very low values, mainly through conversion of methane and surplus fuel in the mill to energy. [ABSTRACT FROM AUTHOR]

This article explores the factors and mechanism driving the land-use conversion at regional level by developing and using an econometric approach which is called the simultaneous equations model (SEM). A case study in Jiangxi Province of China is conducted by establishing the SEM, which consists of three equations including agricultural production, land conversion of cultivated land to built-up area and land conversion of cultivated land to forest cover/grassland from 1988 to 2005. And then this paper employs the method of piecewise estimation to represent the influences of the factors such as population, society, economy, location and geophysical conditions on the process of land-use conversion in Jiangxi Province. Estimation results show that population is a predominant factor driving the land-use conversion at counties, while social and economic factors are determinant factors in the short term for the entire Jiangxi Province. Specifically, the size of agricultural population and the magnitude of agricultural input determine the agricultural production to a large extent; population size, plain area proportion at counties and land management policies together affect the direction and magnitude of conversion between cultivated land and built-up area; agricultural population proportion, terrain slope, grain production and non-agricultural industry promote the conversion of cultivated land to forest cover/grassland. Furthermore, the explored mechanism also reveals the underlying causes of the land use changes driven by a series of factors in Jiangxi Province. Finally, this paper concludes that factors proven to play an important role in driving the land-use conversion need to be considered when the land management agencies make out the land use planning to optimize the land use, expand the agricultural production, and conserve the cultivated land. [ABSTRACT FROM AUTHOR]