Afforestation Patterns Research Articles

Underprediction of extirpation and colonisation following climate and land‐use change using species distribution models

AbstractAimTo evaluate the performance of species distribution models in predicting observed colonisations, persistences and extirpations in response to changes in climate and land use over a multi‐decadal period.LocationSweden.MethodsWe use historical (early 20th century) land use and climate data to build species distribution models for 84 plant species across three provinces of Sweden. Model performance was then evaluated internally using a subset of the historical data for cross‐validation, as well as by using the models to project occurrences to the modern day and validating them with observed occurrences from 1990 to 2020. We then analysed predicted and observed occurrences in the modern period in terms of persistence, extirpation (local extinction) and colonisation in relation to species' habitat and climate associations.ResultsWe found overall high agreement between evaluation methods, although internal evaluation gave consistently higher values for model performance (using true skill statistic, TSS). Overall, extirpations were worst predicted, with on average fewer than one‐third of each species' extirpations being foreseen by the models. Colonisations were better predicted, while persistences were relatively well‐predicted. Predictive accuracy of colonisations was higher for species with relatively warmer temperature associations (climate‐driven expansion), while extirpations were better predicted in cool‐related species (retractions at cool edges). Colonisations of forest‐associated species were more common than predicted (underpredicted), despite widespread patterns of afforestation. Assessing grid‐cell level turnover, we found that in grid cells that experienced the largest changes in terms of climate and land use, predicted extirpations were less likely to have happened.Main ConclusionsWe found that commonly applied modelling approaches have limited ability to predict observed changes in species occurrences, especially extirpations. This suggests that we should take predictions of future biodiversity loss very seriously. However, the ability for species to (at least temporarily) persist in unsuitable conditions could be an opportunity for biodiversity conservation.

Identify a sustainable afforestation pattern for soil carbon sequestration: Considering both soil water‐carbon conversion efficiency and their coupling relationship on the Loess Plateau

AbstractAfforestation is considered to be an important means to improve the ecological environment and mitigate climate change. However, inappropriate vegetation restoration can result in severe soil desiccation and ecosystem degradation in water‐limited regions. Here, we evaluated the effects of six different afforestation patterns on soil moisture content, soil organic carbon (SOC) sequestration, and especially the conversion efficiency of the two on the Loess Plateau, taking abandoned land (Al) as a control sample, and attempting to recognize a suitable afforestation pattern based on these parameters. The six afforestation patterns considered were two single‐species shrub plantations (Caragana korshinskii, Ck and Hippophae rhamnoides, Hr), two single‐species tree plantations (Robinia pseudoacacia, Rp and Platycladus orientalis, Po), and two mixed‐species plantations (Rp, Po, Pinus tabuliformis, Pt, and Ulmus pumila, Up mixed plantations (MP); Po and Pt with terracing [MP + T]). We found that mixed‐species plantations (MP + T and MP) have less soil moisture depletion than single‐species plantations, Ck had the highest SOC sequestration but also had a significant deep soil moisture deficit. MP + T had less deep soil moisture deficit but also had lower SOC sequestration than MP. MP show a better comprehensive effect when considering both soil organic carbon sequestration and soil water‐carbon conversion efficiency. Therefore, multispecies MP represent a potentially valuable approach to sustainable afforestation patterns for soil carbon sequestration on the Loess Plateau. This afforestation pattern has the potential to be applied in other similar semi‐arid and semihumid regions. Our results provide insight into vegetation restoration in areas with degraded land. In future afforestation activities, planners must alleviate regional water pressure, increase soil carbon sequestration by increasing species richness, and select the best combination of species to optimize the stability and sustainability of the plantation ecosystem.

Effects of Afforestation Patterns on Soil Nutrient and Microbial Community Diversity in Rocky Desertification Areas

Karst ecosystems are characterized by the dissolution of soluble rocks, displaying distinctive landscape features such as rugged peaks, steep slopes, and deep valleys. Afforestation is an effective approach for improving soil quality in rocky desertification areas because plants have evolved unique adaptations to thrive in such environments. However, the effects of tree species composition and cultivation patterns on the soil quality, microbial diversity, stability, and functions in rocky desertification areas remain unclear. In this work, four study plots including three types of forests—pure Pinus massoniana plantations, Toona sinensis plantations, mixed coniferous and broadleaf plantations (Pinus massoniana–Betula luminifera forests), and unforested area as the control—were established in a karst desertification area in the Hunan province of China. Soil properties including soil bulk density, soil organic carbon, total nitrogen, total phosphate, soil ammonium nitrogen, nitrate, available phosphate, soil pH, and soil microbial diversity were investigated in the study area. The results showed that the forests significantly increased the soil organic carbon, total nitrogen, and ammonium nitrogen compared to the unforested area. The microbial diversity indicators in mixed forests were significantly higher than those in the Pinus massoniana forests. The dominant bacteria phyla included Proteobacteria, Acidobacteria, and Actinobacteria, while fungi species such as Ascomycota and Basidiomycota were identified in all study plots. In addition, the AVD index evaluation revealed that the mixed forests enhanced the stability of the soil microbial communities compared to the monoculture plantations and unforested plots in rocky desertification areas. The research results indicated that, among the various forest types, the mixed forest was the most effective choice for afforestation in terms of improving the soil quality by changing the soil’s physiological properties in rocky desertification areas. Our study provided guidance and insights for afforestation technology and the optimal allocation of different tree species in the cultivation and management of plantation forests in rocky desertification regions.

Effects of afforestation on soil fungi in rocky mountain areas of North China

AbstractAfforestation has a substantial influence on soil fungal communities by introducing ecological variations within forest ecosystems via the inclusion of distinct tree species (coniferous and broadleaf) and afforestation patterns (pure forests and mixed forests). However, the specific effects of these variations on soil fungal communities require further investigation. Soil samples from birch (B: Betula platyphylla Suk.), larch (L: Larix gmelinii (Rupr.) Kuzen.), and mixed birch and larch (B–L) forests were used in this study, and a shrub–grassland field (S–G) was used as a reference. The abundance, diversity, and community composition of fungi in the soil of the monoculture forest (B and L), mixed forest (B–L), and S–G were studied by high‐throughput sequencing. The results showed that Basidiomycota was the dominant fungus in B and B–L, and the dominant genera were Inocybe and Amanita, respectively. Ascomycota was the dominant fungus in L and S–G, and the dominant genus was Mortierella. Afforestation reduced the richness and diversity of soil fungi. Larch forests were richer in soil fungi than B and B–L forests. Soil organic carbon was the main soil factor affecting the soil fungal community structure. Soil fungal community network changed less after planting L than after planting B and B–L, and the soil fungal community structure was more complex and stable in L than in B and B–L. For soil fungal community composition and function, mixed forests did not show outstanding advantages. Planting monoculture forests may be a more effective afforestation strategy in the rocky mountain areas of North China.

The increased soil aggregate stability and aggregate-associated carbon by farmland use change in a karst region of Southwest China

Land use change can significantly alter the distribution of different soil aggregates, thereby influencing aggregate stability and aggregate-associated organic carbon (OC). However, there is minimal research on the variations in the distribution of soil aggregates, aggregate stability, and aggregate-associated OC following land use change from farmland to afforested land in the karst regions of Southwest China. Undisturbed soil samples were collected from farmland (FL) and three afforestation patterns (bamboo forest: BA; landscape tree planting: LAT; and orange orchards: ORO) converted from farmland in a karst region of Southwest China. These four land uses have similar geographical characteristics (e.g., elevation and slope aspects) and previous framing practices. The distribution of macroaggregate (>0.25 mm), microaggregate (0.053–0.25 mm) and silt + clay fractions (<0.053 mm) and the aggregate-associated OC contents under the four land uses were measured at the 0–10 cm and 10–20 cm depths. The results showed that afforestation converted from FL significantly increased the macroaggregate and microaggregate contents, geometric mean diameter (GMD), and structural stability index (SSI) but decreased the silt + clay fraction content. Compared with FL, the values at the 0–20 cm depth under BA, LAT and ORO increased by 108.79%, 34.89% and 36.56%, respectively, for GMD and by 239.84%, 94.05%, and 123.41%, respectively, for SSI. Land use change and soil aggregate size had obvious influences on soil organic carbon (SOC) content. The SOC content in the bulk soil, macroaggregate, microaggregate, and silt + clay fraction at the 0–20 cm depth after afforestation increased by 26.83%, 45.57%, 27.14%, and 13.80%, respectively, compared to FL. The contributions of macro- and microaggregates to the increase in SOC content in bulk soil were 146% and 78%, respectively, while the silt + clay fractions had a negative effect with a value of 125% after afforestation. The GMD and SSI were positively correlated with the macroaggregate content and SOC content in the bulk soil and different soil aggregates. Although the increase in SOC content in bulk soil and soil aggregates under BA and ORO was significantly higher than that for LAT, the soil aggregate stability under ORO was lower than that under BA. These findings suggest that afforestation increases aggregate ability, SOC content in bulk soil and aggregate-associated OC and that BA might be the optimum choice among the three afforested lands compared for soil sustainability from the perspective of improving carbon sequestration and soil erosion.

Soil sulfur cycle bacteria and metabolites affected by soil depth and afforestation conditions in high-sulfur coal mining areas

This study aimed to clarify the changes in sulfur-driven microorganisms and sulfur metabolic pathways in the vertical soil profile during the restoration of different afforestation types. Soils of varying afforestation patterns (grassland, shrubland, woodland) in high‑sulfur coal mining areas (Gujiao City, China) were analysed to determine the characteristics of the sulfur distribution, microbial community structure, and sulfur metabolites in shallow (10 cm), middle (30 cm), and deep (50 cm) soils. Compared with the area without vegetation, the soil in the planted area had higher total soil S (5.1–58.6 %), Fe (37.5–67.4 %), and Cu (28.3–54.2 %); the content of these elements showed a consistent increase with depth. Afforestation resulted in increased pH by 0.8–1.3 pH units, organic carbon (1.6–2.9 times), total N (30.2–46.9 %), and available N (58.3–78.2 %) in the soil. Additionally, the electrical conductivity of the shallow soil in the three plant cover areas decreased by 78–82 %. The diversity of 16S bacterial showed that different afforestation types shaped the structure of specific microbial communities at different soil depths. Afforestation also showed a promotion of abundance of soil sulfur-related microorganisms (e.g., Desulfovibrio (0.8–34.2 %), Acidiferrobacter (0.3–32.8 %), Acidithiobacillus (1.2–21.7 %), and Thiomonas (0.6–15.6 %)). Plant cover induced the vertical spatial distribution pattern of sulfur metabolites in high-sulfur coal mines showing a shallow > middle > deep layer, and afforestation enhanced the transformation process of sulfur metabolites in shallow soil. The main metabolic pathways for soil sulfur metabolism involve sulfur-containing amino acids, such as cysteine and methionine metabolism, taurine, and hypotaurine. Interaction analysis indicated that Lysobacter, Luteimonas, and Leptospirillum made greater contributions to the changes in sulfur metabolites. The findings from this study suggest that the distribution of sulfur and soil properties in vertical depth soil of different afforestation types in high-sulfur coal mining areas recruit specific bacteria, which drive soil sulfur metabolic conversion and reestablishment of soil sulfur homeostasis, and the shallow layers of the soil were critical areas for turnover of sulfur metabolite. These results provide insights for understanding biochemical sulfur cycling in vertical soil depth under different afforestation models.

中国南亚热带不同造林模式碳汇林土壤碳、氮、磷的积累及化学计量特征

PDF HTML阅读 XML下载 导出引用 引用提醒 中国南亚热带不同造林模式碳汇林土壤碳、氮、磷的积累及化学计量特征 DOI: 10.5846/stxb202112283676 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金青年项目（31100402）；广东省自然科学基金项目（S2011040001125）；广东省林业科技创新专项资金项目（2015KJCX028）；广州市林业科技项目（201806） Characteristics of soil carbon, nitrogen, phosphorus accumulation and their ecological stoichiometry in Chinese subtropical forest under different afforestation patterns Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:碳汇林的固碳效益十分显著，是实现"碳中和"的主要碳增汇途径之一，在研究南亚热带地区不同造林模式碳汇林土壤碳汇的同时，研究碳汇林土壤氮、磷储量及土壤碳、氮、磷的生态化学计量特征，能够为不同造林模式碳汇林的土壤碳、氮、磷储量的评估提供科学依据。采取单因素随机区组设计，选择立地条件基本一致的研究区和4种造林模式（新造林、封山育林、补植套种、更新改造）的碳汇林，分析了不同造林模式土壤有机碳（SOC）、全氮（TN）、全磷（TP）的含量、储量、生态化学计量比，以及微生物生物量碳（MBC）的变化特征。结果表明，不同造林模式碳汇林的土壤理化性质，碳氮磷储量、化学计量比及微生物生物量碳含量差异显著，且土壤碳氮磷储量随土壤深度增加而减少，表现出明显的垂直变化特征。4种造林模式下碳氮比（C/N）介于11.11-17.86，碳磷比（C/P）介于17.00-242.59，氮磷比（N/P）介于1.18-15.99之间，在0-60 cm土层上均以更新改造模式林最低，封山育林模式下C/P和N/P均显著高于其他造林模式。土壤SOC与TN、N/P呈极显著正相关关系，土壤TN与C/P呈极显著正相关关系。综合来看，封山育林模式土壤的碳、氮含量和储量最高，而磷含量最低，说明封山育林模式更有利于土壤碳、氮的累积，而后期表现出土壤磷的缺乏，可能会限制封山育林模式碳汇林后期的碳汇功能。更新改造模式碳汇林的土壤养分限制少，后期碳汇潜力较大。 Abstract:Carbon sink forests is one of the effective ways to achieve "carbon neutrality". Besides soil carbon (C) sink, soil nitrogen (N), phosphorus (P) stocks and stoichiometry were investigated under different afforestation patterns, which provides the theoretical basis for estimating soil nutrition stocks. A single-factor randomized block design was used to investigate C, N, and P contents, stocks, their stoichiometric characteristics and soil microbial biomass carbon in soils with different soil depths under four afforestation patterns including new afforestation, closed mountain afforestation, replanting, and regeneration. The results showed that the storage of soil C, N, and P decreased with soil depth. The range of soil C/N, C/P and N/P under the four afforestation patterns were 11.11-17.86, 17.00-242.59 and 1.18-15.99, respectively. Soil C/P and N/P under closed mountain afforestation were significantly higher than the other afforestation patterns, while regeneration pattern showed the lowest. The soil C was positively correlated to soil N and N/P, soil N was positively correlated with C/P. In summary, the content and stock of soil C and N were the highest under closed mountain afforestation, while phosphorus content was the lowest, indicating that the closed mountain afforestation is an effective afforestation to promote the accumulation of soil carbon and nitrogen. However, the capacity of soil carbon sink under closed mountain afforestation may be weakened by soil phosphorus limitation. Regeneration pattern has less nutrition limitation, which has great potential to sequestration carbon. 参考文献 相似文献 引证文献

Ecological stoichiometric comparison of plant-litter-soil system in mixed-species and monoculture plantations of Robinia pseudoacacia, Amygdalus davidiana, and Armeniaca sibirica in the Loess Hilly Region of China

We examined how afforestation patterns impact carbon (C), nitrogen (N), and phosphorus (P) stoichiometry in the plant-litter-soil system. Plant leaf, branch, stem, and root, litter, and soil samples were collected from mixed-species plantations of Robinia pseudoacacia with Amygdalus davidiana (RPAD), R. pseudoacacia with Armeniaca sibirica (RPAS), and monocultures of R. pseudoacacia (RP), A. davidiana (AD), and A. sibirica (AS) in the Loess Hilly Region. The results showed that in mixed-species plantations, R. pseudoacacia had lower leaf N and P concentrations than in monocultures, while both A. davidiana and A. sibirica had higher leaf N and P concentrations. Soil P limited tree growth in both afforestation models. Mixing R. pseudoacacia with A. davidiana or A. sibirica reduced N-limitation during litter decomposition. Average soil total N and P concentrations were higher in RPAS than in RPAD, and both were higher than the corresponding monocultures. The average soil C:N ratio was the smallest in RPAS, while the average soil C:P ratio was larger in RPAS than in RP. A positive correlation between N and P concentrations, and between C:N and C:P ratios, was found in litter and all plant organs of mono- and mixed-stands. Alternatively, for N concentration and C:N ratio, the correlations between plant (i.e., leaf, branch, root) and litter and between plant and soil were inverse between plantation types. RPAD has an increased litter decomposition rate to release N and P, while RPAS has a faster rate of soil N mineralization. RPAD was the best plantation (mixed) to improve biogeochemical cycling, as soil nutrient restrictions, particularly for P-limitation, on trees growth were alleviated. This study thus provides insights into suitable tree selection and management by revealing C:N:P stoichiometry in the plant-litter-soil system under different afforestation patterns.

Advantage of mixed trees in the trade-off between soil water storage and tree biomass: A meta-analysis from artificially planted forests in Chinese Loess Plateau

Afforestation is an effective measure to combat land degradation and mitigate climate change. However, afforestation tends to consume a tremendous amount of soil moisture while increasing vegetation biomass and coverage. Although convincing evidence indicates that mixed trees have higher resistance and resilience to climate change and natural disturbance than pure trees, it is unclear how tree mixtures affect the relationship between soil water storage and tree biomass. By conducting a meta-analysis of 86 observations from 27 studies, we showed that there was a trade-off between soil water storage and tree biomass in artificially planted trees on the Loess Plateau, with an average root mean square deviation (RMSD) value of 0.22. The RMSD value between soil water storage and tree biomass for mixed trees was significantly lower than that for pure trees, and the relative benefits of the trade-off were biased toward soil water storage. In dry areas (aridity index (AI) < 0.3), the RMSD value between soil water storage and tree biomass of artificially planted trees was the highest, and this value of mixed trees was significantly lower than that of pure trees. In terms of different plantation ages, the RMSD value between soil water storage and tree biomass for mixed trees was significantly lower than that for pure trees in plantations aged >20 years. Additionally, RMSD values between soil water storage and tree biomass under different afforestation patterns were negatively correlated with the initial water storage and soil organic carbon content. Our results show that tree mixtures optimize the trade-off between soil water storage and tree biomass in arid and semiarid areas.

The introduction of Phoebe bournei into Cunninghamia lanceolata monoculture plantations increased microbial network complexity and shifted keystone taxa

Cunninghamia lanceolata is an important timber species and has been widely cultivated in subtropical China. However, monoculture successional patterns lead to multiple ecological problems, such as soil nutrient depletion, biodiversity loss, and forest productivity decline. The introduction of broadleaf species into monospecific C. lanceolata plantations is an effective silvicultural practice driven by the demands to restore soil fertility and produce timber. A comprehensive understanding of how mixed afforestation patterns drive soil microbial community compositions and diversity can aid in the evaluation of the effects of broadleaf trees (Phoebe bournei) on forest soil–plant-microbe ecosystem functions. Therefore, this study aims to explore the effects of conversion from C. lanceolata monoculture plantations to mixed plantations (C. lanceolata-Phoebe bournei) on the soil microbial community by measuring soil physicochemical properties and sequencing the 16S and ITS rRNA genes. The results showed that (1) the effect of forest conversion on bacterial alpha diversity was larger than that on fungal diversity, and the soil microbial community structure of both bacteria and fungi significantly differed between the two interplanting practices; (2) the co-occurrence analysis of bacteria and fungi displayed more connected and complex networks in mixed plantation networks, in which keystone taxa (i.e., Burkholderia and Steroidobacter) might play critical roles in the construction of the microbiome network; and (3) the results from VPA showed that the structure of the soil microbial community was strongly affected by soil environmental factors (e.g., pH). These findings suggest that the introduction of broadleaf species has significant impacts on the soil microbial community, increases the relative abundance of keystone taxa with important functional traits, and drives a more diverse microbial community network in mixed plantations.

Accounting for local temperature effect substantially alters afforestation patterns

Human intervention in forested ecosystems is hoped to perform a fundamental shift within the next decade by reverting current forest loss—a major source of CO2 emissions—to net forest gain taking up carbon and thus aiding climate change mitigation. The demanded extensive establishment of forests will change the local surface energy fluxes, and with it the local climate, in addition to competing with food and fiber production for land and water. Scenario building models encompass this competition for resources but have turned a blind eye to the biogeophysical (BGP) local surface energy flux disturbance so far. We combine the benefit of CO2 sequestration of afforestation/reforestation (A/R) with the additional incentive or penalty of local BGP induced cooling or warming by translating the local BGP induced temperature change to a CO2 equivalent. We then include this new aspect in the land-use model Model for Agricultural Production and their Impact on the Environment (MAgPIE) via modifying the application of the price on greenhouse gases (GHGs). This enables us to use MAgPIE to produce A/R scenarios that are optimized for both their potential CO2 sequestration and the CO2 equivalent local BGP effect, as well as the socio-economic trade-offs of A/R. Here we show that optimal A/R patterns are substantially altered by taking the local BGP effects into account. Considering local cooling benefits of establishing forests triples (+203.4%) the viable global A/R area in 2100 from 116 to 351 Mha under the conditions of the shared socioeconomic pathway 2 (SSP2) scenario driven by the same GHG price. Three quarters (76.0%, +179 Mha) of the additionally forested area is established in tropical climates alone. Therefore, a further neglect of BGP effects in scenario building models undervalues the benefit of tropical forests while simultaneously running the risk of proposing counterproductive measures at high latitudes. However, the induced focus on tropical forestation intensifies the competition with food production where forests contribute most to mitigation. A/R related trade-offs need to be considered alongside their climate benefit to inhibit unintentional harm of mitigation efforts.

Modeling hydrological impacts of afforestation on intermittent streams

Although the majority of river networks across the world are intermittent or ephemeral, afforestation management of these catchments is mostly founded on studies in perennial catchments. The hydrological model CATHY (CATchment HYdrology) was used here to simulate the effects that different degrees of progressive conversion from pasture to plantation have on the streamflow generation in intermittent streams. The model was applied to two rural catchments with different size and topographic features in southwest Victoria, Australia. Simulated scenarios included different levels of plantation establishment in pasture areas planting gradually from downslope to upslope and vice versa. Different models for root water uptake were compared to account for water stress, oxygen stress, and root water compensation. A function of root growth over time was also explored to see how it affected model results. The model results show that complex interactions between topographic features and afforestation patterns are crucial in controlling catchments hydrological behavior. In particular, results show that planting in the prone-saturation areas has the largest effects on streamflow. Oxygen stress has a more significant impact than root water compensation on streamflow changes. A time dependent root growth results in smaller streamflow reduction on average, although with different impacts on the two catchments, also due to the interplay between topography and plantation patterns. Overall, our results show that there are multiple factors affecting the water balance when a catchment is partially or completely afforested and those must be taken into account when implementing forestry management strategies.

Comparison of spatial modelling frameworks for the identification of future afforestation in New Zealand

In 2018, New Zealand announced an ambitious effort to plant one billion trees by 2028 as part of its climate change mitigation plan and Paris Agreement targets for 2030 and 2050. Afforestation will be promoted through a series of incentives, including payments for carbon sequestration linked to New Zealand’s Emission Trading Scheme. Given that afforestation will be pursued voluntarily, the identification of future afforestation areas is paramount to assist policy formulation and avoid unintended land-use outcomes. We identified spatially-explicit drivers of forest gain and the locations most likely to experience afforestation in the country using two distinct spatial modelling frameworks: logistic regressions and artificial neural networks (ANN). Five of the eight most significant drivers of forest gain that have influenced past afforestation patterns according to our logistic regressions (i.e., erosion potential, distance from exotic forests, woody grasslands, grassland productivity, and slope) were also ranked among the ten most influential drivers by the ANN model. These results indicate an overall agreement between the two modelling approaches, despite substantial methodological differences. In the absence of changes in current incentives for afforestation in the country, simulations suggest that the largest afforestation areas would be in the northeast region of the North Island. These findings can assist policymakers and landscape planners to achieve desirable land-use objectives for New Zealand.

Preliminary afforestation effect of the mixed forest Betula alnoides in southern Fujian China

The tissue-cultured seedlings of Betula alnoides were introduced to plant in Wanshiqing Area of Fujian Hua’an Jinshan National Forest Farm and Beijing Area of Fujian Longhai Jiulongling National Forest Farm. B.alnoides was mixed with Castanopsis hystrix with 4 patterns in Wanshiqing Area, and mixed with Cunninghamia lanceolata with three patterns in Beijing Area. After one year the sample plots were set and each tree in the plots was investigated. The results showed the effects of the mix afforestation patterns to the growth of B. alnoides were significant difference in the early stage. The optimal pattern was the pure forest of B. alnoides with the best tree height and DBH. It was possible that the pure forest crowns closed after one year and created a small forest climate. The termites, crickets, Anoplophora chinensis and Batocera lineolata were found damaging to the B. alnoide in Wanshiqing Area, but not in Beijing Area.

Assessment of Land-Use and Land-Cover Change in Guangxi, China

It is increasingly acknowledged that land-use and land-cover change has become a key subject that urgently needs to be addressed in the study of global environmental change. In the present study, supported by the long-time-series of land-use and land-cover data from 1990, 2000, and 2017, we used the land-use transition matrix, Markov chain model and Moran’s I to derive detailed information of the spatial patterns and temporal variation of the land-use and land-cover change; additionally, we highlight the deforestation/afforestation conversion process during the period of 1990–2017. The results show that a total of 4708 km2 (i.e., 2.0% of the total area) changed in Guangxi from 1990 to 2017, while 418 km2 of woodland has been lost in this region. The woodland lost (deforestation) and woodland gained (afforestation) were collocated with intensive forest practices in the past 27 years. The conversions from woodland to cropland and from woodland to grassland were the dominant processes of deforestation and afforestation, respectively. Steep slope cropland was one of the major conversion patterns of afforestation after 2000. This result is mainly explained by the implementation of the “Grain for Green Program” policy and the large-scale development of eucalyptus plantations. Further efforts should be made to control deforestation in this area. These findings can also be used as a reference in the formulation and implementation of sustainable woodland management policies.

The Social Dynamics of Mangrove Forests in Guinea-Bissau, West Africa

Using social and GIS/remote sensing techniques, we analysed the historical, social, political, and economic processes underlying mangrove deforestation and afforestation patterns in Guinea-Bissau to explain the increase in the mangrove forest area between 1990 and 2015. By comparing several regions during the same timeframe, we highlight different ecological dynamics and the complex ways in which diverse societies respond to the same social, economic, and political processes. Our results reveal the importance of identifying the most relevant temporal and geographic scales, and the multiple (and sometimes opposing) environmental and social processes working simultaneously in different places, as well as the potential shortcomings of policy decisions or development or conservation interventions relying on broad estimates. Research efforts to assess threats to and the regeneration capacity of mangrove forests in Guinea-Bissau are thus vital.

南亚热带3种阔叶树种人工幼龄纯林及其混交林碳贮量比较

Enhancement of the carbon storage of plantation ecosystems by optimizing afforestation patterns has beenextensively researched. In the present study,we investigated carbon storage and allocation in an 8-year-old Erythrophleum fordii stand( PE),a Castanopsis hystrix stand( PC),a Mytilaria laosensis stand( PM),and a mixed E. fordii × C. hystrix× M. laosensis stand( MECM) in subtropical China. We showed that the average carbon contents of different organs in E.fordii,C. hystrix,and M. laosensis ranged from 509.0 g / kg to 572.4 g / kg,474.2 g / kg to 553.4 g / kg,and 512.8 g / kg to556.3 g / kg,respectively. We determined significant differences in carbon contents among different organs of the same tree species. Within the same organs,the average carbon contents of different stands were ranked as follows: E. fordii( 539.3 g /kg) M. laosensis( 532. 7 g / kg) C. hystrix( 515. 3 g / kg). In the shrub,herb,and litter layers,the highest carbon contents among the four stands occurred in PM,followed by MECM,PC,and PE. The carbon contents of the 0—10 cm,10—30 cm,30—50 cm,and 50—100 cm soil layers differed significantly among the four stands and were the highest in PM,followed by PC,MECM,and PE. The ecosystem carbon storages were ranked as PM( 308.0 t / hm2) MECM( 182.8t / hm2) PC( 180.2 t /hm2) PE( 135.2 t /hm2). We determined significant differences in average carbon contents within and among stands( P 0.05),but no significant differences in the total ecosystem carbon storage between MECM and PE( P 0. 05). Our results indicate that the mode of afforestation can markedly influence the carbon storage and allocation of plantations. In mixed stands,C. hystrix and E. fordii will benefit from an increase in aboveground biomass carbon,but not from accumulation of soil carbon. On the other hand,in monoculture,M. laosensis will benefit from the sequestration of aboveground biomass carbon and from accumulation of soil carbon. Therefore,the afforestation mode for carbon sequestration forests should be selected according to the carbon accumulation characteristics of the representative tree species.

Contribution to the Restoration of Mixed Forests in Central Vietnam

This article investigates options for reforestation in degraded forests in Central Vietnam within the context of sustainable forestry and presents a forest management plan for the forests around the community of Phong My. In the past, the area was damaged during the war between Vietnam and the United States and after that by overcutting. Forests have gradually been degraded and now they are replaced by plantations of fast-growing Acacia (Acacia mangium). After final harvests, the stand remnants are burnt and the burnt area is again regenerated via artificial regeneration of Acacia. Here, we propose several mixtures in which Acacia stands can be augmented with other tree species. A proposed system of afforestation and subsequent management is given here with the goal of encouraging mixed species, multiple cohort stands, and disincentivizing the method of slash-and-burn. The proposed afforestation patterns were also used to calculate the future number of seedlings required to enable the enlargement of quality forests at the expense of degraded ones.

Patterns of afforestation on abandoned agriculture land in Latvia

Abandonment of agriculture land and subsequent natural afforestation have been common features of the contemporary Latvian rural landscape, particularly in the period since 1990. This process affects the structure, ecology and visual qualities of the landscape. The study examines spatial characteristics of afforestation in relation to various environmental factors. The study was conducted in the central part of Latvia, where there is abundant abandoned agriculture land and a great variety of spatial afforestation patterns. The most typical patterns in this area were linear, mosaic, and continuous afforestation, as well as development of afforestation from the forest edge. The results of the study show that the spatial patterns of natural afforestation of abandoned agriculture fields can be very diverse, and do not follow the classical secondary succession model. Afforestation can be delayed by a dense cover of herbaceous vegetation for a period of up to 20 years. There are many interacting factors that affect succession and development of afforestation patterns, such as soil properties, size and configuration of fields, previous land use and also the random nature of plant colonization by seed. Further studies on afforestation patterns would help to understand better their ecological, economic and social effects as well as to determine optimal solutions for the use of abandoned agriculture land.

Processes Associated with Afforestation near Public Lands

This paper empirically examines patterns of afforestation in vicinities immediately surrounding National Park/National River and National Forest lands. The public lands (Ozark National Forest and Buffalo National River) are found on the Ozark Plateau and represent different management mandates. A spatial lag model is presented comparing two LANDSAT images in conjunction with sociodemographic measures covering the same time period. The findings here make two important points. First, the public land boundaries are shown to act as ecological switches. Second, results underscore the importance of understanding how publicly managed lands with different mandates function within the larger social as well as geophysical landscape matrix. Empirical evidence demonstrates that public lands set aside for “preservation” (Buffalo National River) are associated with greater afforestation, whereas public lands set aside for “conservation and use of natural resources” (Ozark National Forest) are surrounded by less afforestation.