Natural Regeneration Capacity Research Articles

Floristic Diversity and Natural Regeneration of Miombo Woodlands in the Rural Area of Lubumbashi, D.R. Congo

Increased anthropogenic pressure on forest resources leads to deforestation and forest degradation, significantly limiting the regeneration capacity of native woody species and consequently the restoration of miombo woodlands in anthropized habitats within the rural area of Lubumbashi. This study assessed miombo species’ diversity and natural regeneration capacity through floristic inventories in three different habitats (unexploited forests, degraded forests, and post-cultivation fallows). The results reveal that for the adult stratum, unexploited and degraded forests exhibit higher dendrometric (density, mean square diameter, basal area) and floristic parameter (taxa, genera, families) values compared to post-cultivation fallows. Furthermore, the regeneration of miombo woody species is higher in degraded forests (21 taxa; 105 juveniles/plot). However, regarding the sapling’s stratum (1 cm ≤ dbh < 10 cm), the three habitats display similar situations. Additionally, the floristic composition and diversity of unexploited and degraded forests show a significantly higher similarity (76.50%) among them compared to these habitats and the post-cultivation fallows (56.00%). These findings indicate that miombo woodlands have the potential to regenerate and maintain floristic diversity even in anthropized habitats, particularly in degraded forests. To sustain this natural regeneration capacity of miombo woody species and promote the restoration of forest cover and its floristic diversity, it is imperative to determine the rotation period after habitat exploitation and regulate anthropogenic activities and late bush fires, particularly in anthropized habitats at the village level.

Synergistic enhancement of regeneration capacity and ecological functions of Robinia pseudoacacia L. plantations in the Loess Plateau

Contemporary forestry research prioritizes the advancement of high-quality forestry, especially in ecologically vulnerable areas. To this end, enhancing the ecological function and natural regeneration capacity of planted forest stands is crucial. This study investigated synergistic or trade-off relationships between stand regeneration capacity and the ecological functions (including water conservation, soil conservation, carbon sequestration, and understory plant diversity) of Robinia pseudoacacia L. (RP) plantations in the Caijiachuan watershed of the Loess Plateau using Root Mean Square Deviation. The results indicated that stand regeneration capacity exhibited synergistic, moderate trade-off, and high trade-off relationships with soil and water conservation, stand carbon sequestration, and understory plant diversity, respectively. Notably, stand regeneration capacity had a synergistic relationship with the overall forest ecological function (sum of the above functions), suggesting that the overall forest ecological function can be simultaneously improved by enhancing stand regeneration capacity. Redundancy analyses revealed that the regeneration capacity was primarily influenced by soil moisture content (SMC), stand density (SD), total transmitted light, herbaceous species richness, litter accumulation, and soil available phosphorus (AP). According to the stand optimization model, the highest regeneration capacity of RP was observed under the following conditions: 1742 trees·hm−2 for SD, 15.29 % for SMC (higher than the mean value of 33.53 % for the existing RP), 41.69 mg·kg−1 for AP (higher than the mean value of 15.84 %), and 1.84 for LAI (lower than the mean value of 20.0 %). Therefore, to achieve the simultaneous enhancement of the regeneration capacity and overall ecological function of RP stands, foresters should prioritize adjusting SD to an appropriate range through thinning or replanting. Additionally, regular pruning of specific branches of individual trees is essential to mitigate the adverse effects of high LAI on stand regeneration. Where feasible, soil moisture and nutrients can also be increased, but excessive levels of AP should be avoided.

Neighborhood Competition and Understory-Associated Vegetation Are Important Factors Influencing the Natural Regeneration of Subtropical Mountain Forests

Natural regeneration is deemed essential for maintaining biodiversity and ecosystem stability. Previous studies, however, have primarily concentrated on regions exhibiting limited environmental and climatic variability, overlooking the classification of natural regeneration based on age and source. Research conducted at the mesoscale, characterized by increased environmental variability and the incorporation of neighborhood competition and understory-associated vegetation, enhances our comprehension of the multifaceted influences on natural regeneration. To comprehend this issue, this study implemented 60 plots, each measuring 20 m × 20 m, across five distinct areas of Chongqing, China. Twenty explanatory variables were chosen from five diverse categories: understory vegetation, neighborhood competition, stand structure, climatic factors, and environmental factors. And the naturally regenerated species were classified into seedlings and saplings, as well as endogenous and exogenous species, based on their age and origin. We examined the response of the different categories of natural regeneration to various factors and constructed a structural equation model (SEM) for significant factors to investigate their direct and indirect effects on natural regeneration. A total of 61 regenerated tree species belonging to 29 families and 42 genera were found in the study area, and the naturally regenerating species with high importance values were Quercus fabri, Robinia pseudoacacia, Alangium chinense, Cunninghamia lanceolata, and Ligustrum lucidum. It was found that neighborhood competition and understory-associated vegetation explained the largest proportion (more than 50%) of the variation in the different categories of natural regeneration, and forests with clumped distribution (W), a high mingling index (M) and strong competition (H) had a reduced natural regeneration capacity. Understory-associated herbs significantly reduced natural regeneration and the crowdedness index (C) significantly inhibited the understory-associated herbs, thus indirectly promoting natural regeneration. The shrub cover is significantly and positively correlated with the number of naturally regenerated plants and can be used as an indicator of a forest community’s regeneration potential. Understanding the differences in the importance of various factors at the mesoscale, as well as their direct and indirect impacts, can help us further comprehend the mechanisms of natural regeneration and provide a foundation for the sustainable development of forests.

Transcriptome Analysis Reveals the Impact of Arbuscular Mycorrhizal Symbiosis on Toona ciliata var. pubescens Seedlings

Toona ciliata var. pubescens, known as “Chinese mahogany”, has high commercial value and is classified as a level II priority protected wild plant in China. However, due to overexploitation and its poor natural regeneration capacity, natural T. ciliata var. pubescens forests show varying degrees of decline in habitat adaptability. Arbuscular mycorrhizal fungi (AMF) symbiosis presents a potential strategy to enhance its regeneration. In this study, T. ciliata var. pubescens seedlings were inoculated with Septoglomus viscosum, followed by RNA-Seq analysis to compare gene expression differences between AMF-inoculated (AMI) and non-mycorrhizal (NM) treatments three months post-inoculation. A total of 16,163 differentially expressed genes (DEGs) were upregulated by AMF colonization, constituting 96.46% of the total DEGs. Specifically, 14,420 DEGs were exclusively expressed in the AMI treatment, while 35 DEGs were completely silenced. Most of the upregulated DEGs were located on the cell membrane, nucleus, and cytoskeleton and functioned in protein binding, S-adenosylmethionine-dependent methyltransferase activity, and lipid binding during cellular/macromolecule/protein localization, intracellular/protein transport, the cell cycle, and signal transduction. Additionally, lots of key genes related to oxidative stress responses, nutrient transport, and small GTPase-mediated signal transduction were found to be upregulated. These results suggest that AMF inoculation may enhance root cell growth by activating genes involved in nutrient uptake, stress responses, signal transduction, and substance transportation. This study elucidates the molecular mechanisms underlying the growth promotion of T. ciliata var. pubescens through AMF symbiosis, laying a foundation for the future application of AMF in its natural forest regeneration.

Determination of fire intensity after forest fire by remote sensing: marmaris case study

Forest fires in Turkiye are a frequently encountered natural disaster, especially in recent years. After a fire, identifying the plant species to be used in the area and determining the intensity of the fire in the region are important for assessing the area’s capacity for natural regeneration. In this process, geographic information systems and remote sensing methods and techniques are commonly used tools for assessing burned areas and fire intensities following forest fires. In this study, one of Turkiye’s devastating fires, the Marmaris fire, which began on June 21, 2022, is examined. Landsat satellite images, geometrically and radiometrically corrected, were utilized to determine the intensity of the Marmaris fire. As part of the method, the NBR (Normalized Burn Ratio), dNBR (Difference Normalized Burn Ratio), NDVI (Normalized Difference Vegetation Index), and dNDVI (Difference Normalized Difference Vegetation Index) indices were used for burned area detection. As a result of the study, information about the burned areas, fire intensities, and the regenerative capabilities of post-fire vegetation growth has been obtained. Furthermore, suitable pioneer plant species, considering the fire intensity, have been suggested for the restoration of burned landscape areas after the fire. This study is expected to serve as a guide for relevant public institutions and organizations, particularly the General Directorates of Forestry, enabling them to respond most effectively after fires and implement reforestation efforts considering the usage areas and growth capabilities of needle-leaved and broad-leaved plants.

Fragmented areas due to agricultural activity: native vegetation dynamics at crop interface (Montecaseros, Mendoza, Argentina)

Plant communities fragmented by agricultural activities were analyzed in a 250-ha area in eastern plains of Montecaseros, Gral. San Martín Department, Mendoza, Argentina. A phytosociological method assessed different sites along a gradient of human intervention, from natural environments with no evidence of altered native vegetation to maximum farming modification, also including cleared and abandoned fields. Soil analyses supplemented the characterization of six plant communities. A scrubland physiognomy dominates the area, with species of the genera Larrea, Atriplex and Lycium. Tillage and crop abandonment can alter natural factors involved in soil formation, causing deterioration and exerting selective pressure on species colonizing these degraded environments. Evaluating natural vegetation before land clearing for agriculture is essential to assess, through species that indicate environmental conditions, edaphic limitations hindering crop establishment and affecting productivity. The conservation of natural communities on private lands destined for agriculture is valued. Plant communities fragmented by agricultural activities were analyzed in a 250-ha area in eastern plains of Montecaseros, Gral. San Martín Department, Mendoza, Argentina. A phytosociological method assessed different sites along a gradient of human intervention, from natural environments with no evidence of altered native vegetation to maximum farming modification, also including cleared and abandoned fields. Soil analyses supplemented the characterization of six plant communities. A scrubland physiognomy dominates the area, with species of the genera Larrea, Atriplex and Lycium. Tillage and crop abandonment can alter natural factors involved in soil formation, causing deterioration and exerting selective pressure on species colonizing these degraded environments. Evaluating natural vegetation before land clearing for agriculture is essential to assess, through species that indicate environmental conditions, edaphic limitations hindering crop establishment and affecting productivity. The conservation of natural communities on private lands destined for agriculture is valued. Highlights: This study aimed to characterize plant communities in natural and intervened environments, in a representative area of the fragmentation processes caused by agriculture in the Monte Province (Mendoza, Argentina). Plant biodiversity plays a strategic role in ecosystemic provision of goods and services necessary to human health and well-being. Cultivable land is a vulnerable and scarce resource, particularly in drylands, where ecosystems have low capacity for natural regeneration. Tillage and crop abandonment can alter natural factors involved in soil formation, causing deterioration and exerting selective pressure on species colonizing these degraded environments. In agricultural land, clearing can give rise to a mosaic of landscapes: productive crops merge with abandoned crops and fragments of natural fields. Evaluating natural vegetation before land clearing for agriculture is essential to assess, through species that indicate environmental conditions, edaphic limitations hindering crop establishment and affecting productivity. Studies of vegetation dynamism in private lands contribute to plan and implement sustainable land management, tending to recover and conserve biodiversity in degraded soils, considering all associated ecosystem services.

Effects of Shading on the Growth and Photosynthetic Fluorescence Characteristics of Castanopsis hystrix Seedlings of Top Community-Building Species in Southern Subtropical China

Castanopsis hystrix is a major community-building species in the top communities of southern subtropical China, with a high natural regeneration capacity. However, excessive logging and the introduction of exotic tree species have substantially reduced the area of natural forest patches of Castanopsis hystrix, and seedling regeneration is essential for the long-term continuation of Castanopsis hystrix populations. To explore the effects of light intensity on the seedling emergence and early growth of Castanopsis hystrix, shading experiments were conducted under four shading treatments (0%, 40%, 60%, and 80%). The growth, biomass accumulation, and distribution, the quality index of seedlings, the morphology and structure of the root systems of seedlings, and the leaf chlorophyll content and chlorophyll fluorescence properties of seedlings under different shading treatments were analyzed. The results displayed the following: (1) Shade intensity impacts growth of Castanopsis hystrix seedlings and biomass allocation, with optimal results observed at 60% shade, leading to the promotion of organic matter production in leaves and the limitation of stem growth. (2) Using a multi-indicator composite index, it was determined that seedling quality for Castanopsis hystrix peaks at 60% shade intensity. (3) Shade significantly impacts the morphology and structure of Castanopsis hystrix’s root system, with most root characteristics peaking at 60% shade, indicating a substantial increase in root development compared to no-shade conditions. (4) The D-values indicated the most suitable shade intensity for seedling growth to be 60%, suggesting that Castanopsis hystrix seedlings are sensitive to light and excessive light can be detrimental to their growth. (5) The 60% shade treatment showed the maximum values of chlorophyll fluorescence characteristics and photochemical activity, with variations in energy conversion efficiency and dissipation reflected in parameters like photochemical burst coefficient (qP), photochemical burst coefficient (qN), the actual photometric yield of PSII under light acclimation (YII), and the maximum photosynthetic electron transport rate in photoinhibition (ETR), thereby supporting seedling growth and maintaining the normal function of photosynthetic organs. In conclusion, 60% shade treatment can effectively improve the growth and photosynthetic characteristics of Castanopsis hystrix seedlings and promote the accumulation of nutrient elements, ultimately promoting their growth.

Long-term in toto Imaging of Cellular Behavior During Nerve Injury and Regeneration.

Accidental wounding of the peripheral nervous system leads to acute neural dysfunction. Normally, chronic deficits are overcome because peripheral nerves naturally regenerate. However, various genetic and metabolic defects can impair their natural regenerative capacity, which may be due to neuron-extrinsic mechanisms. Therefore, characterizing the behavior of multiple cells during nerve injury and repair in vivo is a pressing need in regenerative medicine. Here, we detail a method for precise wounding of sensory axons in zebrafish, followed by high-resolution in toto long-term quantitative videomicroscopy of neurons, Schwann cells, and macrophages. This protocol can be easily adapted to study the effects of targeted genetic or metabolic disruptions in zebrafish and other suitable organisms, as well as for screening pharmacological agents with therapeutic potential. Graphical overview.

Sexual and asexual propagation of Syzygium maire, a critically endangered Myrtaceae species of New Zealand

ABSTRACT Syzygium maire (swamp maire) is an endemic New Zealand Myrtaceae tree species. Current threats to this species include habitat destruction, myrtle rust, declining remnant populations and low capacity for natural regeneration. Large-scale replanting for conservation/restoration initiatives would mitigate against these threats. However, there is limited information available on propagation of this species. In this study, we looked at sexual propagation using seed germination and asexual propagation using softwood cuttings. For seed germination, we examined the effect of seed pretreatments (intact fruit or de-pulped seed) and temperature settings (15/25°C or 20/30°C) to optimise germination. For softwood cutting propagation, we investigated the diameter of the cuttings (1–2 mm or 3–5 mm) and application of exogenous indole-3-butyric acid (IBA) (0, 1.5, 3.0, or 4.5 g L−1) on their efficacy of producing adventitious rooting. The most critical factor for seed germination was the removal of seed pulp. De-pulping the seeds shortened the mean time to germination and positively affected the germination percentage, regardless of the incubation temperature. Germination percentage of ≥94.5% was achieved in seeds sown without pulp. Propagation by softwood cutting of 1–2 mm in diameter was possible without IBA treatment (63.3% of cuttings rooted), but the application of 1.5 g L−1 IBA increased the rooting percentage (to 75%), thereby inducing the production of a higher number of roots. Seed germination and softwood cutting were effective strategies to propagate S. maire. The findings of this research contribute to the knowledge of propagation and restoration of S. maire populations.

Relevance of Trees and Forests to Sustainable Development: Perspectives of Key Rural Actors in Selected Communities, Ghana

Abstract In consonance with the universal quest for sustainable development, the United Nations (UN) declared 17 global goals in 2015 known as the sustainable development goals (SDGs). Scholarly literature has highlighted the relevance of trees and forests (TFs) to this quest from various perspectives. However, the perspectives appear elitist, as they tend to exclude those of some seemingly ordinary but actually crucial actors whose activities directly affect the growth, health, and population of TFs, namely small-scale farmers, chainsaw operators, and artisanal miners operating particularly in rural areas in developing countries. The study examined the excluded perspectives of the said actors in selected rural comminutes in Ghana on the relevance of TFs to SD. The study was guided by the SDGs in its data collection, analysis, and reporting approach. Focus group discussions were held with the farmers and miners, while in-depth interviews were held with the chainsaw operators. The actors‘ perspectives generally indicated that TFs were relevant to seven, not relevant to six, and somehow relevant to four of the 17 SDGs. Although the actors saw TFs as important for SD, they (actors) were not favourably disposed to tree-planting for purposes of land restoration because they saw TFs as renewable resources with natural regenerative capacity. Stronger advocacy and more intensive sensitization by the central and local governments, forestry commission, and other pro-environmental organisations, institutions, and agencies on the importance of growing, nurturing, and conserving TFS for SD are recommended. Furthermore, the government should enforce regulations to stop the destruction of TFs by the actors to ensure a sustainable green environment for sustainable development.

Contested Living with/in the Boeng Chhmar Flooded Forests, Tonle Sap Lake, Cambodia

The paper is based on empirical research of a territorial transect in Cambodia’s Tonle Sap floodplain. The flooded forests of the Tonle Sap Lake are determined by a significant seasonal flood of up to 13 m, where a large gradient of wetness and alluvia flow and dramatically transform the territory. The paper zooms into a case study of the inhabited RAMSAR area of Boeng Chhmar with its five floating villages, which are dispersed along seasonal waterways. Boeng Chhmar is one of the richest symbiotic habitats in the world and its inhabitants completely rely on the flooded forest’s natural cycles for settling, subsistence fishing, and forest−gathering activities. From two opposite landscape transformation processes, Khmer indigenous practices and State development procedures, the paper unravels the logics of settling, coexistence, and contestation. On the one hand, local daily practices are embedded in seasonal floods and forest lifecycles, coexisting, and reconfiguring the inhabited wild for subsistence living. On the other hand, State development through history has centered on (de)−(re)forestation and modern landscape construction for commercially exploitative practices. Forest logging and large−scale fishing lots extracted enormous quantities of natural resources and compromised the health and natural regenerative capacity of the ecological system. This also undermined the ago−old legacy of inhabitant’s ways of settling in and with the landscape. Today, State operations face challenges from both nature itself and cultural resistance. The findings for the paper are based on multi−scalar interpretive mapping. The tracing of morpho−typologies and landscape transformation processes allows multiple narratives to be translated into spatial terms. The coexistence and contestation in Boeng Chhmar and the Tonle Sap can provide spatial insights into contemporary forest and water urbanisms, especially concerning local material cultural practices and landscape transformation.

Wnt Signaling in Heart Development and Regeneration.

Cardiovascular diseases are the leading cause of death worldwide, largely due to the limited regenerative capacity of the adult human heart. In contrast, teleost zebrafish hearts possess natural regeneration capacity by proliferation of pre-existing cardiomyocytes after injury. Hearts of mice can regenerate if injured in a few days after birth, which coincides with the transient capacity for cardiomyocyte proliferation. This review tends to elaborate the roles and mechanisms of Wnt/β-catenin signaling in heart development and regeneration in mammals and non-mammalian vertebrates. Studies in zebrafish, mice, and human embryonic stem cells demonstrate the binary effect for Wnt/β-catenin signaling during heart development. Both Wnts and Wnt antagonists are induced in multiple cell types during cardiac development and injury repair. In this review, we summarize composites of the Wnt signaling pathway and their different action routes, followed by the discussion of their involvements in cardiac specification, proliferation, and patterning. We provide overviews about canonical and non-canonical Wnt activity during heart homeostasis, remodeling, and regeneration. Wnt/β-catenin signaling exhibits biphasic and antagonistic effects on cardiac specification and differentiation depending on the stage of embryogenesis. Inhibition of Wnt signaling is beneficial for cardiac wound healing and functional recovery after injury. Understanding of the roles and mechanisms of Wnt signaling pathway in injured animal hearts will contribute to the development of potential therapeutics for human diseased hearts.

Trophic interactions and feedbacks maintain intact and degraded states of Hawaiian tropical forests

AbstractFeedbacks within ecosystems can lead to internal reinforcement of the current state providing ecosystem resilience. Often, multiple biotic interactions across trophic levels play a role in such feedbacks, yet these are generally studied independently, obscuring the relative importance of interactions among different factors. We look at various potential feedbacks in intact and degraded mesic forests on Hawaiʻi Island where managers have planted native Acacia koa (koa) trees in an attempt to jumpstart succession in former cattle pastures. These restoration forests, however, have not undergone secondary succession, instead maintaining a koa overstory with an exotic pasture grass understory. We contrasted different trophic level processes that influence the capacity for natural understory regeneration: feedbacks between bird‐mediated seed rain and fruiting understory (“top‐down”), as well as links between understory composition and microhabitats for native seed germination (“bottom‐up”). We quantified bird‐mediated seed rain under canopy trees along transects spanning intact, fragmented, and restoration forests. Along these transects, we established plots around focal overstory trees to measure abundance of fruiting understory species, ground cover (e.g., exotic grass, bryophyte), and obtained estimates of bird density to evaluate the contribution of each of these factors to seedling abundance. We also used a factorial seed addition/grass removal experiment to directly compare the influence of seed rain and germination substrate. We found evidence of both top‐down and bottom‐up feedbacks that reinforced the current state of each forest type. In the intact and fragmented forests, the combination of comparatively high seed rain and ample germination substrate is likely critical for maintaining a diverse forest system. In contrast, exotic grasses exhibit priority effects in restoration forests, inhibiting seed germination and effectively negating any benefits that could be derived from bird‐mediated seed rain. Such internal reinforcement suggests that active, rather than passive, restoration would be beneficial to increase forest diversity in restoration areas.

重庆喀斯特生境中桢楠种群结构与动态特征

PDF HTML阅读 XML下载 导出引用 引用提醒 重庆喀斯特生境中桢楠种群结构与动态特征 DOI: 10.5846/stxb202106171607 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 重庆市自然科学基金项目（cstc2020jcyj-msxmX0244）；中央高校基本科研业务费专项（XDJK2020B037）；国家自然科学基金项目（31500399） Population structure and dynamic characteristics of Phoebe zhennan S. Lee in karst areas of Chongqing 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:桢楠是我国珍稀渐危树种，国家二级保护植物，野生多散生于海拔1500 m以下的亚热带常绿阔叶林中。而喀斯特生境岩石裸露、土壤浅薄贫瘠、岩溶干旱频发，理论上并不适合喜湿耐荫且喜酸性土壤的桢楠生长及幼苗更新。因此重庆市大足区和永川区喀斯特生境中的天然桢楠种群可能存在一定的更新困难。为明确这两个桢楠种群的生存现状及动态特征，采用野外调查法，从径级结构、静态生命表、存活曲线、结构动态及分布格局等方面分析桢楠种群结构及其数量动态规律，以期预测种群未来发展趋势，为喀斯特地区桢楠种群的保护、群落更新及植被恢复提供理论基础。结果表明：（1）大足区桢楠种群的年龄结构趋于稳定型，而永川区桢楠种群的年龄结构为增长型。两地区幼苗充足但死亡率高。（2）静态生命表及相关曲线分析显示，两个桢楠种群存活数量总体上随径级增大而减少；两个桢楠种群的生存期望值在不同径级间存在波动，大足区桢楠种群在第Ⅱ径级而永川区则是第Ⅳ径级期望值最高。（3）两个种群的存活曲线均为Deevey-Ⅲ型，即幼树死亡率较高，并且种群的增长速度较为缓慢。（4）大足区种群为随机分布，永川区种群为集群分布；种群各生长发育阶段均为集群分布，但聚集强度随着龄级的增加而减弱。桢楠种群在喀斯特地区生长周期长，天然更新能力较强但对外部干扰敏感。建议加强对幼苗的抚育工作，提高幼苗存活率，促进桢楠种群的自然更新和恢复。 Abstract:Phoebe zhennan S. Lee is a rare and endangered tree species in China, a nationally protected secondary plant. It is mostly scattered in the wild in subtropical evergreen broad-leaved forests below 1500 m above sea level. As the primary populations are almost destroyed, the existing resources are limited and scattered. Karst habitat has exposed rocks, shallow and barren soil and frequent drought. In theory, it is not suitable for the growth and seedling regeneration of P. zhennan, which likes humidity, shade and acid soil. Therefore, it may be difficult to renew the natural P. zhennan population in karst habitats in Dazu District and Yongchuan District of Chongqing. To explore the survival status and distribution model of the two P. zhennan populations, the field survey method is used to analyze the structure and the dynamic law of the populations and their quantity, by assessing the diameter structure, static life table, survival curve, structural dynamics and distribution pattern. It is hoped that the future development trend of the population can be predicted, and the theoretical basis for the protection, community renewal and vegetation restoration of the karst area will be provided. The results showed that:(1) the age structure of P. zhennan population in Dazu District tended to be a stable type, while it was an increase type in Yongchuan District. Both areas had abundant seedlings but with high mortality rates. (2) The individual numbers of both populations of P. zhennan generally decreased with the diameter class increased. The life expectation of the two P. zhennan populations fluctuated between different diameter classes. It was the highest in the diameter class Ⅱ in the population of P. zhennan in Dazu District, while it highest in the diameter class Ⅳ in Yongchuan District.(3) Both populations had Deevey-Ⅲ type survival curves, that was, the mortality of young trees was relatively high, and a relatively low population growth rate. (4) The population in Dazu District was randomly distributed, while that of the Yongchuan District was consolidated. P. zhennan were clustered populations at the growth and development stage, but their strength weakened with the growth of the age group. The population of P. zhennan in the karst region had a long growing time, a strong capacity for natural regeneration but sensitive to external disturbances. It is suggested to enhance seedling selection and improve seedling survival to promote natural renewal and restoration of P. zhennan population. 参考文献 相似文献 引证文献

Spatial exploration, dendrometric characteristics and prediction models of wood production in a stand of Acacia schaffneri in Durango, Mexico

Abstract Degraded vegetation is the result of a process that affects structural and functional characteristics. Tree species from the Acacia genus are very important to the ecosystem in semi-arid lands due to their participation in the recovery of highly degraded areas. One of the most important species among this genus is A. schaffneri. The status of a forest stand is determined according to its structure, including height, stratum and density. Remote sensing is a valuable method for estimating volumetric stocks and associated changes in forest populations over established periods of time. The objective of this research was to estimate wood volume of A. schaffneri using remote sensing, and to complement that information with the results obtained from an estimation method based on forest measurements. The results obtained showed that the crown area was the dendrometric variable that can be used in a wood volume prediction model. In the exploratory analysis between dendrometric variables and remote sensing showed low and negative associations were observed in the four stations analyzed. There are conservation problems due to anthropogenic activities, among which stands out the intensive grazing that results in a decrease of the natural regeneration capacity of Acacia schaffneri.

Generating Multifunctional Landscape through Reforestation with Native Trees in the Tropical Region: A Case Study of Gunung Dahu Research Forest, Bogor, Indonesia

Gunung Dahu Research Forest (GDRF) is a 250 ha tropical degraded land reforested by native dipterocarps species. The reforestation success was valued by evaluating the planted trees’ growth performance, their potential timber stock, natural regeneration capacity, soil improvement, biological interdependence, and environmental services. This scientific report used a combination of literature review and also primary data processing to describe the reforestation success within the area. A hilly species of Shorea platyclados showed the best growth performance with its average diameter and height of 43 cm and 23 m, respectively, with its mean diameter annual increment of 2.1 cm/year and the predicted standing stock at 220 m3/ha. Six Shorea species were identified to show their natural regeneration capacity and the occurrence of ectomycorrhizal fruiting bodies, predominantly by the genus Rusula, determined the establishment of biological interdependency at the site. Reforestation improved soil organic matters as revealed by high soil porosity (51.06–52.32%) and infiltration rate (120–155.33 mm/h). The reforested landscape also ensures a continuous water supply and provides an economic benefit for the community. Thus, planting native trees for reforesting degraded tropical landscapes is prospective and may deliver multiple benefits in an ecological and economic view.

Active Restoration Initiates High Quality Forest Succession in a Deforested Landscape in Amazonia

Amazonia is well known for its high natural regeneration capacity; for this reason, passive restoration is normally recommended for the recovery of its degraded forests. However, highly deforested landscapes in southern Amazonia require active restoration. Since restoration methods can shape the quality and speed of early forest recovery, this study aimed to verify how active restoration pushes sites stably covered with exotic grasses towards forest recovery. We evaluated early forest succession at active restoration sites, i.e., soil plowing, direct seeding of pioneer species, and seedling stock planting at low density. We analyzed forest structure, diversity, and species composition in two age classes, 0.5–3.5 and 4.5–7.5 years old. As reference, we evaluated sites able to naturally regenerate in the same region. We sampled 36 active restoration and 31 natural regeneration sites along the Madeira River, southern Amazonia. Active restoration triggered succession to similar or higher levels of forest structure than sites where natural regeneration was taking place. The most dominant species did not overlap between active restoration and natural regeneration sites. The overall composition of species was different between the two restoration methods. Dominant species and size class distribution show that active restoration is performing successfully. Soil preparation combined with a high availability of seeds of pioneer trees resulted in a high stem density and basal area of facilitative pioneer trees. Planted seedlings added species diversity and increased density of large trees. Interventions to increase the odds of natural regeneration can be effective for non-regenerating sites in resilient landscapes.

Natural regeneration in urban forests is limited by early-establishment dynamics: implications for management.

Urban forested natural areas are valuable ecological and social resources, but long-term sustainability of these habitats is challenged by environmental and social factors associated with urban ecosystems. Advances in city-scale assessments of urban forests have increased the resolution of forest community types and conditions, allowing for improved understanding of ecological function, such as natural regeneration, in these urban habitats. By applying metrics of tree regeneration that are commonly used for the management of rural forests, urban ecologists can test the potential for traditional forest management strategies within our cities. In this study, we compare urban and rural oak-hickory forest composition and structure and the capacity for natural regeneration in the New York metropolitan area. Specifically, we use two metrics of advance regeneration that describe the abundance of seedlings and saplings at different size classes to test whether this management for natural regeneration is a viable option. We found differences in recruitment dynamics between urban and rural forests that have implications for the sustainability of these forests and new management strategies. First, after controlling for forest community type, species composition in urban and rural sites was significantly different across multiple strata and within the seed bank. Species-specific capacity for natural regeneration was different in urban and rural sites, signaling the possibility of divergent successional trajectories. Second, while differences in species composition exist, both urban and rural sites were dominated by native species across all forest strata except for urban seed banks. Third, despite finding significantly lower average annual seedling abundance in urban (1.9 seedlings/m2 ) compared to rural (7.1 seedlings/m2 ) sites, we observed greater density of saplings in urban forests, and no significant difference in stocking index between sites. These findings suggest that early-establishment barriers to recruitment are greater in urban forest sites. However, once established, seedling transition into advance regeneration stages may not be different between site types, and advance regeneration may, in some cases, be more viable in urban forested natural areas. These results highlight functional differences between urban and rural forest recruitment dynamics that may impact on the future community composition of oak-hickory forests in the two landscape settings.

Assessment of Structure and Natural Regeneration Capacity of Avicennia Marina and Bruguiera Gymnorrhiza Species of Mangroves in Mida Creek Kilifi County, Kenya

The study assessed the structure, natural regeneration capacity and Biotic agents of Avicennia marina and Bruguiera gymnorrhiza species in Mida creek, Kilifi County. The study used both cross section and descriptive research design. Avicennia marina species was more dominant with a greater complexity index (A2.7, B0.4), basal area (A588cm2, B484cm2) and mean height (A26m, B10m) compared to Bruguiera gymnorrhiza species with both having an aggregate dispersion pattern. During dry season, Height, and diameter of Avicennia marina had a correlation of 0.56 while Bruguiera gymnorrhiza species had 0.78. During rainy season both had a correlation of 0.67. B. gymnorrhiza species had more straight poles than A. marina species, 75.3% of B. gymnorrhiza trees assessed had straight pole compared to 1.7% of Avicennia marina trees. Both Avicennia marina and Bruguiera gymnorrhiza species had fair regeneration capacity where the number of seedlings was greater than saplings and number of saplings was less than mature trees. Littoraria scabra fed mostly on micro-organisms and algae, Littoraria Glabrata fed mostly on mud surface, Sesarma guttata and Sesarma leptosoma fed on mangrove leaves, Cerithidea decollata fed on deposits and organic matter, Terebralia palustris and Selatium elongatium fed more on algae and leaves, Sesasrmi ortmanni, Metopograpsus oceanicus and Neosarmatium meinerti fed on leaves and young propagules, Barnacles and Oyster bunch on the roots and stems of B. gymnorrhiza species. Biotic agents were insignificant in affecting regeneration capacity of A. marina and B. gymnorrhiza species however combinations with climatic and anthropogenic factors affected Regeneration capacity of the two species.

Impact of logging operations on forest ecosystem in the Khantai mountain region and forest cover mapping

Forests in Mongolia yield low productivity and are vulnerable to disturbances from drought, fire, pests, and illegal logging. Such forests can quickly lose their ecological balance. Logging activities in these areas are limited in monitoring and controls. This study assesses two different logging operations for their natural regeneration capacity by comparing the composition of the soil, soil organisms, physical and chemical properties, and forest cover change after the completion of logging operations. The logging operations were analyzed in two different regions, the Khartsai and Tariakhtai threshold in Selenge soum, Bulgan province. A skyline logging operation was undertaken on Khartsai threshold in 1983 and a tractor logging operation (clear-cutting) on Tariakhtai threshold in 1987. After the completion of the logging, the forests were naturally regenerated. In 2002, soil samples were collected and soil organisms and physical and chemical properties were examined. Satellites images were also used to evaluate forest cover changes after the end of the logging operations. Significant differences in the naturally regenerated tree species in the skyline logging, tractor logging, and natural forest areas were observed. Average tree ring growth was 0.9 mm in the skyline logging site, 0.6 mm in the tractor logging site, and 1.2 mm in the natural forest. Based on forest cover changes observed in satellite images, the density of naturally regenerated tree species in the natural forest area was higher than that in the skyline logging area. In contrast, the latter recorded a higher density than that in the tractor logging area. Therefore, processing of satellite images of forest cover changes with high-resolution data provides valuable information for the local forest community and helps decision-makers in their further actions.