Mixed Pine Research Articles

PHYTOPATHOLOGICAL MONITORING OF DANGEROUS OUTBREAKS DISEASE OF FOREST TREES WITH USE METHOD OF CHANGING RADIAL INCREMENTS IN THE CONDITIONS OF THE POLISKY NATURE RESERVE

PHYTOPATHOLOGICAL MONITORING OF DANGEROUS OUTBREAKS DISEASE OF FOREST TREES WITH USE METHOD OF CHANGING RADIAL INCREMENTS IN THE CONDITIONS OF THE POLISKY NATURE RESERVE

Exploring soil bacterial diversity in different micro-vegetational habitats of Dachigam National Park in North-western Himalaya

Dachigam National Park (DNP), in Zabarwan mountains of north-western Himalaya constitutes a region of high biodiversity with greater endemism. DNP is known for its unique micro-climate together with distinct vegetational zones providing home to variety of threatened and endemic plant, animal, and bird species. However, studies on soil microbial diversity in fragile ecosystems of north-western Himalaya in general and DNP in particular are lacking. This was thus a maiden attempt to study variations in soil bacterial diversity of DNP with respect to changing soil physico-chemical properties, vegetation, and altitude. Soil parameters depicted significant variations among different sites with highest values for temperature, OC, OM and TN being 22.2 ± 0.75 °C, 6.53 ± 0.32%, 11.25 ± 0.54%, 0.545 ± 0.04% from site-2 (low altitudinal grassland site) in summer and lowest of 5.1 ± 0.65 °C, 1.24 ± 0.26%, 2.14 ± 0.45% and 0.132 ± 0.04% at site-9 (high altitudinal mixed pine site) in winter. Bacterial CFU showed significant correlations with soil physico-chemical attributes. This study led to the isolation and identification of 92 morphologically varied bacteria with the highest (15) from site-2 and lowest (04) from site-9 which post BLAST analysis (via 16S rRNA analysis) depicted presence of only 57 distinct bacterial species under taxonomic phylum, Firmicutes and Proteobacteria. Nine species were widely spread (i.e., isolated from > 3 sites), however, most bacteria (37) were restricted to a particular site. Diversity indices ranged between 1.380 to 2.631 (Shannon–Weiner’s index); 0.747 to 0.923 (Simpson’s index) with highest values for site-2 and lowest for site-9. Index of similarity was highest (47.1%) between riverine sites (site-3 and site-4) whereas two mixed pine sites (site-9 and site-10) showed no similarity.

Sanitary condition of pine plantations of the Polyssia of Zhytomyr region

The sanitary condition of pine plantations in the conditions of Polissia of Ukraine was assessed. Derevostan grows in different types of forest vegetation conditions B2GDS, B3GDS, C2GDS, C3GDS. According to the data of 27 circular trial plots, which were established during 2018–2020 in the territory of the State Enterprise Zhytomyr LH Berezivske Forestry, the State Enterprise Korostyshivsk LH Ivnitske Forestry, the State Enterprise Korostensky LH APC Melenivske Forestry, which covered the typical growing conditions of pine plantations of Zhytomyr Oblast. The index of sanitary condition showed that the pine forest belonged to strongly weakened stands. Analyzing the sanitary condition during the research period, it is worth noting that in 2018, the tree stand of the plantations in the Ivnytsia Forestry was weakened, and the average index was 2.42. In Berezivsk and Melenivsk forests, the sanitary condition index was 2.58 and 2.67, which indicates that the degree of damage is average, and the plantations are strongly weakened. Based on the results of the research, it was established that in 2019 the sanitary condition in the Bereziv forestry improved and amounted to 2.12. By state category, the largest number of I category is 2019 – 40.0 %, 2019 II – 27.6 %. In the Ivnytsia forestry, the sanitary condition index was 2.52, the plantations were greatly weakened. In the Meleniv Forestry, the average sanitary condition index of 2.44 indicates that the tree stand is weakened. It is proven that in 2020 the sanitary condition improved compared to other years of research and amounted to 2.11. In Ivnytsia Forestry, the sa-nitary condition remains very weak. In the Meleniv Forestry, the average sanitary condition index was 2.29, which indicates that the tree stand is weakened. It has been established that pests, diseases and forest fires are the biggest deterioration of the sanitary condition in the territory of Zhytomyr Oblast. To prevent the development of these negative factors, it is necessary to create mixed pine plantations, to carry out timely felling of forest care. Key words: condition categories, sanitary condition index, type of fo-rest vegetation conditions, completeness, Scots pine.

State and productivity of mixed stands with silver birch and Scots pine in Ukrainian Polissya

The aim of the study was to assess the current state of silver birch (Betula pendula Roth.) stands in Ukrainian Polissya, as well as to identify optimal composition resulting in productive and resilient mixed birch forests. It was found that in forests managed by the State Forest Resources Agency of Ukraine, birch stands grow on an area of 352 800 ha, covering 5.6% of the total area of forests in Ukraine. Within the study region of Ukrainian Polissya, birch stands cover 294 900 ha making 12.3% of the total forest area. Naturally originated birch stands were found to dominate in the study region, with 65.4% of vegetative stands and 25.2% of those grown from seeds. However, planted stands significantly prevail in terms of growing stock as compared to natural ones. In Ukrainian Polissya, silver birch trees grow as a part of mixed pine and birch forests on 632 400 ha. Our study found that mixed pine and birch stands with 80–90% of Scots pine and 20–10% of silver birch in the composition are the most productive.

Labile carbon input and temperature effects on soil organic matter turnover in subtropical forests

The objective of this study was to assess the effects of labile organic carbon (LOC) input on the dynamic turnover of soil organic matter (SOM) with temperature in subtropical forests. Soil samples were collected from three subtropical forests: an evergreen broadleaf forest, a mixed pine and broadleaf forest, and a pine forest. To simulate LOC inputs, soil samples were supplemented with 13C-glucose at levels of 0, 0.2, 0.6, and 1.2 mg C g−1 soil. The soils with the LOC treatments were incubated for six weeks at temperatures of 15, 25, and 35 °C. Results showed that the increase in LOC inputs reduced the priming effects of SOM decomposition significantly, whereas native SOM mineralization increased with temperature. The preferential utilization of LOC by microorganisms reduced SOM decomposition, resulting in net SOC increases with LOC inputs. In the temperature range, the net increases in SOC with the LOC inputs were −0.19 to 0.56 mg C g−1 soil. Moreover, the LOC inputs aided microbial anabolism and promoted the formation of new mineral-associated organic matter and the aggregation of particulate organic matter, resulting in carbon sequestration. Among the forest soils, the soil with the highest organic carbon content, total nitrogen, and carbon to nitrogen ratio (i.e., the mixed forest soil) had the lowest priming effects and was the most conducive to net carbon increase. The priming and carbon sequestration caused by the LOC inputs were not sensitive to temperature changes. Our findings suggest that the increase in the supply of LOC has the potential to alleviate SOM decomposition and increase carbon storage in subtropical forest soils.

Manufacture of LDPE Plastic Waste Briquettes a Mixed Pine Needles and Clay with Various Compositions as Alternative Fuels

Along with the times, the need for fossil fuels as the main energy source to support various activities of human life is also increasing. it is necessary to treat plastic waste to produce briquettes as an alternative fuel. Briquettes are solid fuels that can be used as an alternative energy source that has a certain uniform shape. In Tarakan City, we often encounter a lot of waste, especially plastic waste that is difficult to decompose, one of which is Low Density Polyethylene (LDPE). LDPE is one type of plastic that we encounter everyday in various applications and often ends up as waste such as plastic bags and plastic wrap. The use of plastic waste into briquettes with the addition of pine fruit obtained results from a mixture with various ratios of 30:50:20 the value of ash content and water content is in accordance with SNI with a calorific value and electrical energy generated of 3182.4Q(j)and 3183,39W(j)

Long-term nitrogen-addition-induced shifts in the ectomycorrhizal fungal community are associated with changes in fine root traits and soil properties in a mixed Pinus koraiensis forest

Nitrogen (N) deposition has marked effects on the structure and function of global forest ecosystems. Many forest tree species rely upon a symbiotic association with ectomycorrhizal (ECM) fungi to enhance nutrient acquisition, which affects nutrient and carbon (C) dynamics in forest ecosystems. A better understanding of the characteristics of ECM fungal diversity and composition and their primary determinants under N deposition will help us to identify the mechanisms underlying N-induced effects on forest nutrient and C cycling. In the present study, we explored the effects of long-term N addition (10 years) on the diversity and community composition of ECM fungi identified from fine roots of Corylus mandshurica, Pinus koraiensis and Tilia amurensis in a mixed temperate forest on Changbai Mountain in north-eastern China. We observed that N addition decreased the Shannon and Simpson indices of the ECM fungal community colonizing C. mandshurica and T. amurensis. Neither the Chao1 index nor the observed species richness of the ECM fungal community colonizing the three species was impacted by N addition. Nitrogen addition significantly decreased the fine root and stele diameter of C. mandshurica, and it significantly decreased the cortical thickness of fine roots of both P. koraiensis and T. amurensis. Nitrogen addition had a consistently negative effect on the mycorrhizal colonization of fine roots, but it did not affect the branching intensity of fine roots of the three tree species. Nitrogen addition altered the ECM fungal community composition, which was closely associated with fine root traits, such as mycorrhizal colonization, and edaphic factors, such as soil pH, soil total N concentration and soil CN ratio. An altered ECM fungal community composition was accompanied by shifts in the nutrient acquisition ability, as characterized by exploration types of ECM fungi. These findings have important implications for a better understanding of the effects of a changing ECM fungal community on the C and N cycling of forest ecosystems under increasing N deposition.

Mixed Pine Forests in a Hotter and Drier World: The Great Resilience to Drought of Aleppo Pine Benefits It Over Other Coexisting Pine Species

Drought is an important driver of forest dynamics in the Mediterranean region. The forecasted increase in drought frequency and severity can notably influence tree growth, forest structure, composition and productivity. Understanding how coexisting tree species respond to drought is thus crucial to understand which are less vulnerable and will perform better in a warmer and drier world. To assess drought vulnerability, we used dendrochronology to study the radial growth trends and responses to a drought index of four pine species (Pinus halepensis, Pinus pinea, Pinus nigra, and Pinus sylvestris) coexisting in North-eastern Spain. We reconstructed the growth of each species and evaluated their short- and long-term growth response to drought for the common period 1980–2017. The growth of the four pine species depended on water availability and high early spring temperatures impacted the growth of P. nigra and P. sylvestris negatively. The occurrence of a severe drought between 2005 and 2007 lead to marked growth reductions in the four species, but it was greater in magnitude in P. pinea and P. halepensis in 2005, and in P. nigra in 2007. The results of basal area increment models at the individual tree level suggested that P. halepensis trees grow more than the rest of species. After accounting for age and drought effects, P. nigra and P. sylvestris displayed negative growth trends in the 2008–2017 period while P. pinea and P. halepensis displayed positive growth trends. P. sylvestris was the most resistant species and P. pinea the less resistant. Conversely, P. halepensis and P. pinea were slightly more resilient than P. sylvestris. Moreover, P. sylvestris was the species displaying the highest autocorrelation and the lowest coefficient of variation in ring-width indices. A marked drop in the autocorrelation of P. pinea ring-width index was observed in response to the 2005 drought. These results indicate that all study species are vulnerable to drought but in different degrees. The strong resilience capacity of P. halepensis suggests that it will better thrive in a drier future, but mixed pine forests, such as the one here studied, may contract or become rare due to the strong sensitivity of P. pinea to drought and the lower post-drought performance of P. nigra and P. sylvestris.

Small Area Estimation in Diverse Timber Types Using Multiple Sources of Auxiliary Data

Abstract Informed forest management requires reliable information. As the demand for finer scale estimates has increased, so has the cost for obtaining them from design-based ground sampling. Small area estimation (SAE) is an estimation technique that leverages ancillary information to augment design-based samples with the goal of increasing estimate precision without increasing ground-based sample intensities. This work presents three case studies spanning an industrial timberland ownership in the United States making use of SAE techniques in operational forest inventories. Case studies include an inventory of pre-thin plantation loblolly pine (Pinus taeda L.) stands that had achieved crown closure in Alabama and Mississippi, a mixed pine–hardwood inventory in Alabama, and pre-thinning plantation Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) in Washington State. Using area-level SAE techniques, vegetation indices derived from 10 m Sentinel imagery were shown to reduce estimate uncertainty for common stand parameters. Additionally, when available, lidar and age were shown to offer additional improvements in estimate precision. The results of this study indicate the operational potential for using commonly available auxiliary data for producing forest parameter estimates with enhanced precision. The implications of these findings span multiple inventory objectives including, for example, commercial forest management, carbon accounting, and wildfire fuel assessments. Study Implications: Forest management requires reliable quantitative information for informed decisions. Data from ground-based forest inventories are commonly used to construct design-unbiased direct estimates. Due to logistical and cost constraints, samples often do not provide estimates with sufficient precision for making confident decisions. The statistical estimation procedure, small area estimation, is able to leverage linearly related ancillary data across areas of interest to form composite estimates that have less uncertainty than direct estimates alone. This study shows how combining ground-based data with auxiliary data from remote sensing and stand records produced more precise estimates of forest stand parameters in three distinct timber types spanning a large ownership in the United States. Results indicate that significant inventory efficiency and confidence can be realized by incorporating commonly available auxiliary data into the estimation of forest characteristics.

Growth and formation of Scots pine stands in Eastern Polissia of Ukraine

Abstract The purpose of the research is to study the current state, features of growth and formation of Scots pine (Pinus sylvestris L.) stands in Eastern Polissia of Ukraine. The structure of pine stands by origin, age, the density of stocking, site indices, forest types and health condition was analysed. Features of the formation of stands were studied at the permanent sample plots. Visual assessment of health condition, as well as signs of pest and disease damage of trees, other defects and external signs that caused stem defects was carried out. The age structure of pine stands was not optimal: there was an excess of mature stands and a lack of young stands. The health condition of mixed pine stands was relatively better than that of pure pine stands. Mixed pine stands were characterised by high biological resistance and accumulated significant wood stock under regular sylvicultural maintenance. The dynamics of forestry and evaluation indicators of reference pine stands were evaluated and comparison of their growth with stocked pine stands was performed.

Different xylogenesis responses to atmospheric water demand contribute to species coexistence in a mixed pine–oak forest

Seasonal patterns of wood formation (xylogenesis) remain understudied in mixed pine–oak forests despite their contribution to tree coexistence through temporal niche complementarity. Xylogenesis was assessed in three pine species (Pinus cembroides, Pinus leiophylla, Pinus engelmannii) and one oak (Quercus grisea) coexisting in a semi-arid Mexican forest. The main xylogenesis phases (production of cambium cells, radial enlargement, cell-wall thickening and maturation) were related to climate data considering 5–15-day temporal windows. In pines, cambium activity maximized from mid-March to April as temperature and evaporation increased, whereas cell radial enlargement peaked from April to May and was constrained by high evaporation and low precipitation. Cell-wall thickening peaked from June to July and in August–September as maximum temperature and vapour pressure deficit (VPD) increased. Maturation of earlywood and latewood tracheids occurred in May–June and June–July, enhanced by high minimum temperatures and VPD in P. engelmannii and P. leiophylla. In oak, cambial onset started in March, constrained by high minimum temperatures, and vessel radial enlargement and radial increment maximized in April as temperatures and evaporation increased, whereas earlywood vessels matured from May to June as VPD increased. Overall, 15-day wet conditions enhanced cell radial enlargement in P. leiophylla and P. engelmannii, whereas early-summer high 15-day temperature and VPD drove cell-wall thickening in P. cembroides. Warm night conditions and high evaporation rates during spring and summer enhanced growth. An earlier growth peak in oak and a higher responsiveness to spring–summer water demand in pines contributed to their coexistence.

Year-round multi-scale habitat selection by Crested Tit (Lophophanes cristatus) in lowland mixed forests (northern Italy)

Determining how animals respond to resource availability across spatial and temporal extents is crucial to understand ecological processes underpinning habitat selection. Here, we used a multi-scale approach to study the year-round habitat selection of the Crested Tit (Lophophanes cristatus) in a semi-natural lowland woodland of northern Italy, analysing different habitat features at each scale. We performed Crested Tit censuses at three different spatial scales. At the macrohabitat scale, we used geolocalized observations of individuals to compute Manly's habitat selection index, based on a detailed land-use map of the study area. At the microhabitat scale, the trees features were compared between presence and absence locations. At the foraging habitat scale, individual foraging birds and their specific position on trees were recorded using focal animal sampling. Censuses were performed during both the breeding (March to May) and wintering (December to January) seasons. At the macrohabitat scale, the Crested Tits significantly selected pure and mixed pine forests and avoided woods of alien plant species, farmlands and urban areas. At the microhabitat scale, old pine woods with dense cover were selected, with no significant difference in the features of tree selection between the two phenological phases. At the foraging habitat scale, the species was observed spending more time foraging in the canopies than in the understorey, using mostly the portion of Scots Pine (Pinus sylvestris) canopies closer to the trunk in winter, while during the breeding period, the whole canopy was visited. Overall, breeding and wintering habitats largely overlapped in the Crested Tit. Based on our findings, lowland Crested Tits can be well defined as true habitat specialists: they are strictly related to some specific coniferous woodland features. Noteworthily, compared to other tit species, which normally show generalist habits during winter, the Crested Tit behaves as a habitat specialist also out of the breeding season. Our study stressed the importance of considering multi-scale (both spatial and phenological) habitat selection in birds.

湘西石漠化区3种造林模式土壤真菌群落结构差异

PDF HTML阅读 XML下载 导出引用 引用提醒 湘西石漠化区3种造林模式土壤真菌群落结构差异 DOI: 10.5846/stxb202008072061 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中央级科研院所基本科研业务费重点项目（CAFYBB2019SZ003）；中南林业科技大学研究生科技创新基金（CX20192026） Differences of soil fungal community structure under three afforestation modes in rocky desertification region of Western Hunan Province Author: Affiliation: Fund Project: “Degradation mechanism and restoration technology of typical forests in South China 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:湘西石漠化地区是我国生态系统脆弱而又敏感的区域，土壤微生物在维持石漠化区森林生态系统结构和功能稳定中发挥重要作用。选取石漠化地区立地条件相同的32年生的马尾松纯林、光皮桦纯林及马尾松-光皮桦混交林为研究对象，以立地条件相似的未造林荒地演变成的灌草群落作为对照，比较分析石漠化地区不同造林模式对土壤真菌群落结构和多样性的影响及其主要驱动因素。采用Illumina HiSeq第二代高通量测序技术，分析了3种森林土壤真菌群落组成及多样性。结果表明，不同造林模式下土壤真菌优势类群不同，光皮桦、马尾松-光皮桦混交林以及石漠化灌草地土壤真菌优势门均为子囊菌门（Ascomycota），且在石漠化灌草地相对丰度最大，为64.0%；马尾松则以担子菌门（Basidiomycota）为优势类群，其相对丰度占57.9%。混交林土壤真菌物种总数和Shannon指数显著高于马尾松和光皮桦林地，整体上真菌群落多样性表现为：未造林灌草地 > 混交林 > 马尾松林 > 光皮桦林。与未造林灌草地相比，马尾松-光皮桦混交林和光皮桦纯林显著提升了土壤有机碳（SOC）和全氮（TN）含量。Mantel test检验结果显示，真菌群落结构与全磷（TP）、有机碳（SOC）、铵态氮（NH4+-N）、硝态氮（NO3--N）、全氮（TN）、pH和含水量（SWC）具有显著相关性（P<0.05），其中土壤SOC、TN、pH值对真菌群落结构影响最大。冗余分析（RDA）结果发现，子囊菌（Ascomycota）与pH、TP、SOC、TN、AP、NO3--N含量均呈正相关；担子菌门（Basidiomycota）和被孢霉门（Mortierellomycota）主要与NH4+-N成正相关，与pH、TP、SOC、TN、AP、NO3--N呈负相，而罗氏菌门（Rozellomycota）与SWC呈正相关（P<0.05）。综上，相比针叶纯林，石漠化地区针阔混交林能通过增加土壤SOC、TN而显著提高真菌群落多样性，促进土壤肥力状况的提升。此研究结果可以为石漠化区人工植被恢复以及土壤肥力管理提供依据。 Abstract:Rocky desertification area in Western Hunan province is a fragile and sensitive area of ecosystem in China. Soil microorganisms play an important role in maintaining the stability of forest ecosystem structure and function in rocky desertification area. Thirty two year-old pure Pinus massoniana forest, pure Betula luminifera forest and mixed Pinus massoniana and Betula luminifera forest in rocky desertification area with the same site conditions were selected as the research objects. The non-forested shrub grassland with the similar site conditions was taken as the control to compare and analyze the influence of different afforestation modes on soil fungal community structure and diversity and their main driving factors. The composition and diversity of soil fungal communities in three forests were analyzed by Illumina HiSeq second-generation high-throughput sequencing technology. The results showed that the dominant groups of soil fungi were different under different afforestation modes. The dominant phylum of soil fungi in Betula luminifera, mixed forest and non-forested shrub grassland were Ascomycota, and the relative abundance was the largest in non-forested shrub grassland, which was 64.0%. Basidiomycota was the dominant group in Pinus massoniana, its relative abundance accounted for 57.9%. The total number of soil fungal species and Shannon index of mixed forest were significantly higher than those of Pinus massoniana and Betula luminifera forest. On the whole, the diversity of fungal community was as follows:non-forested shrub grassland > mixed forest > Pinus massoniana forest > Betula luminifera forest. The contents of soil organic carbon (SOC) and total nitrogen (TN) in the mixed forest and Betula luminifera pure forest were significantly higher than those in non-forested shrub grassland. Mantel test showed that fungal community structure was significantly correlated with total phosphorus (TP), SOC, ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N), TN, pH and water content (SWC) (P<0.05). Soil SOC, TN and pH had the greatest impact on fungal community structure. Redundancy analysis (RDA) showed Ascomycetes were positively correlated with pH, TP, SOC, TN, AP and NO3--N content; Basidiomycetes and Mortierella were mainly positively correlated with NH4+-N, and negatively correlated with pH, TP, SOC, TN, AP and NO3--N. There was a positive correlation between Rozellomycota and SWC. In conclusion, compared with pure coniferous forest, coniferous and broad-leaved mixed forest in rocky desertification area can significantly improve the diversity of fungal community by increasing soil SOC and TN, and promote the improvement of soil fertility. The results can provide basis for artificial vegetation restoration and soil fertility management in rocky desertification area. 参考文献 相似文献 引证文献

Mixed pine and spruce stands in the Luga-Volkhov and Valdai-Tikhvin landscape districts of the Leningrad Region

Pine- and spruce-dominatedmixed stands occupy a substantial part of the forested area. Depending on soil and hydrological conditions of different landscapes, stands of different forest types and tree stand composition dominate. Modern forestry is focused on growing monodominant stands, but it is worth noting that mixed stands have higher productivity and stability. This work is devoted to identifying the patterns of distribution of mixed stands by forest type in different geographic landscapes. For the study, two landscape districts of the Leningrad Region (Valdaysko-Tikhvinsky and Luzhsko-Volkhovsky) with landscape mosaics of different structure were selected. The dominant forest types and types of mixed forest stands were determined by summing the areas of each plant association. To carry out the calculations, data of the state forest inventory of the Leningrad Region were used. In the course of this study, it was found that blueberry forest type was the most common forest type in mixed stands. Most of the landscapes of the study region were dominated by spruce-deciduous stands, but in some landscapes with hilly relief, a predominance of spruce-pine stands was observed.

The influence of forest growing conditions and stand composition on the growing stock of pine and spruce stands of Shimsky forest unit of the Novgorod region

Using as an example one district forestry unit of the Novgorod region, located in two contrasting landscapes, we studied the formation of stands with different proportions of pine and spruce in the stand composition. The aim of the study was to study pure and mixed pine stands in a narrow range of forest growing conditions in order to identify economically valuable combinations and the most productive stands in terms of forest stand composition. To identify statistically significant differences between spruce and pine stands, a comparative analysis of the mean values and the coefficients of variation of forest inventory characteristics was used. The analysis of variance was used to find differences between stands of different composition. According to the results of the comparative analysis by forest type, the only significant difference in growing stock was between spruce stands of the herbaceous-meadow and fresh blueberry forest types. For the rest of the spruce forest types, no significant differences in growing stock were found. In terms of the growing stock, the most productive are forest stands with 60% of trees been spruce or pine, and pure pine stands in the green moss group of forest types in the given landscape conditions.

Legacy effects of seed dispersal mechanisms shape the spatial interaction network of plant species in Mediterranean forests

Abstract Seed dispersal by frugivores plays a key role in structuring and maintaining tree diversity in forests. However, little is known about how the spatial legacy of seed dispersal and early recruitment shapes spatial patterns and the spatial interaction network of plant species in mature forest communities. We analysed two fully mapped mixed Pine–Oak forest communities using spatial point pattern analysis to determine (a) the detailed structure of the intraspecific spatial patterns of saplings and adults, (b) the intra‐ and interspecific spatial interaction of saplings, adults and saplings relative to adults, (c) the spatial patterns of species richness at the community level and (d) whether seed dispersal mechanisms affect the plant–plant interaction networks and the ratio of adult to sapling neighbourhood densities used as surrogate for spatial self‐thinning. The intraspecific spatial patterns of saplings and adults showed in general complex nested cluster structures that were similar for sapling and adult stages, despite substantial self‐thinning in some dry‐fruited species. The spatial network of saplings was characterized by positive spatial interactions. Adults of several tree species facilitated saplings in their proximity; however, adults of dry‐fruited species, but not those of fleshy‐fruited ones, lost almost all positive interactions that occurred at the sapling stage. Besides, interaction strength between adults was positive and often significantly stronger if both species were fleshy‐fruited. At the community level, the forests were structured into multispecies clumps across all life stages. Synthesis. Our analyses highlight the importance of the spatial legacy of seed dispersal and early recruitment in the assembly of plant communities. Particularly, animal seed dispersal can lead to multispecies clusters and positive spatial associations across life stages in Mediterranean forests, with surprisingly little signatures of negative interactions. Our analysis suggests that changes of the spatial structure across plant life stages are driven by seed dispersal mechanisms and subsequent spatial self‐thinning, generating a spatial footprint at the sapling stage that conditions the long‐term interactions between adult plants. Combining spatial point pattern analysis with network analysis and species traits is a promising way to disentangle the processes underlying observed patterns of local diversity.

Diversity and distribution of the large centipedes (Chilopoda: Scolopendromorpha) in the Phia Oac - Phia Den National Park, Vietnam

The scolopendromorph fauna of the Phia Oac - Phia Den National Park, northernmost Vietnam has been studied. As a result, a total of 17 species in eight genera and three families have been recorded in five different types of habitats (wood forest, bamboo forest, wood-bamboo mixed forest, pine forest, and grassland-shrubs) and from three elevation range (&lt;1,000 m, 1,000–1,600 m, and &gt;1,600 m). Scolopendridae is the most diverse family with nine recorded species. Of the five habitats, most species have been found in wood forests and wood-bamboo mixed forests (11 species each habitat), and at the elevation range of 1,000–1,600 m (15 species). The research also recommended that this number does not reflect the true biodiversity of this region; more intensive surveys are needed to have a better understanding of the scolopendromorph diversity in the Phia Oac - Phia Den National Park.

Sapling recruitment in mixed stands in the Northern Plateau of Spain: a patch model approach

Our modelling approach shows the predominance of the facilitative over the competition effects in controlling the regeneration of the studied species, thus pointing out to intra- and inter-specific coexistence mechanisms. Natural regeneration is a main issue in the management of continental Mediterranean forests. Ensuring natural forest regeneration is therefore vital for preserving ecosystem function under climate warming and increased frequency and intensity of extreme droughts. In this study, we evaluated intraspecific and inter-specific relationships between saplings and adult trees in mixed Pinus pinea-Quercus ilex-Juniperus stands in the Spanish Northern Plateau. Data were gathered from five 50 m × 60 m plots that covered different stand densities. Adult trees, saplings, and stumps were positioned, and height and diameter were measured. We developed a patch model to predict the probability of occurrence and abundance of saplings of the three species in 2.5 m × 2.5 m patches using a zero-inflated model. We considered as predictive variables abundance of adult trees, stumps, and saplings of each species, both in a patch and in its adjacent patches. Saplings of the three species showed a cluster pattern. The abundance of saplings of the three species was positively related with the current or past presence of their conspecific adult trees. The presence of adult trees of Pinus pinea plays a main role in both Quercus ilex and Juniperus dissemination. Our modelling approach shows the predominance of the facilitative effects over the competition effects in controlling the regeneration of the three species, pointing out to intra- and inter-specific coexistence mechanisms. The simulations suggested that to perpetuate the mixture, it is necessary to apply intense release cuttings in Pinus pinea trees once seedlings have been successfully established.

Soil physico-chemical properties have a greater effect on soil fungi than host species in Mediterranean pure and mixed pine forests

Soil fungi are fundamental drivers of forest ecosystem processes. Soil physico-chemical parameters and vegetation features such as host type or stand structure can affect soil fungal communities. However, there is a lack of comprehensive studies describing the relative importance of niche processes (soil physico-chemistry and forest structural drivers) versus neutral processes (geographical distance) driving soil fungal community assemblages, especially in less-studied drought-prone ecosystems such as Mediterranean forests. In this study, we performed Pacific Biosciences sequencing of internal transcribed spacer 2 amplicons to characterize the soil fungal community composition and diversity of 42 forests dominated by either pure Pinus nigra, Pinus halepensis or Pinus sylvestris or a P. nigra–P. halepensis or P. nigra–P. sylvestris mixture. Our specific aims were to identify and disentangle the relative importance of the main soil characteristics and the spatial and forest structural factors that accounted for the greatest proportion of fungal community variation along a regional gradient in the Mediterranean Pre-Pyrenees. Soil parameters accounted for the greatest significant proportion of the total variance in the overall fungal community (25%), in the mycorrhizal (23%) and saprotrophic (22%) communities, while geographical distance accounted for 14% of the variance in the overall fungal community, 7% in the mycorrhizal and 22% in the saprotrophic communities. Conversely, forest structure did not significantly affect the soil fungal community, as fungal composition and diversity did not differ significantly among the pine hosts. Moreover, pH, followed by P and the C:N ratio explained the largest differences in the composition of the overall fungal community and in the mycorrhizal fungal community. By contrast, the largest proportion of differences in saprotrophic composition were explained by geographical distance, closely followed by the C:N ratio and N. Our results show that, in these Mediterranean pine forests, soil parameters are the most important driving forces shaping soil fungal communities at the regional scale given that ectomycorrhizal and saprotrophic fungi were more influenced by soil physico-chemical parameters or geographical distance than by Pinus species or forest structural variables. Finally, P content in soils also emerged as a significant factor driving differences in mycorrhizal communities.

Initial plant community responses to hardwood control treatments in restoration of remnant longleaf pine (Pinus palustris) woodlands

Changes in land use over the past century have contributed to substantial losses of longleaf pine (Pinus palustris) woodlands in the southeastern USA and replacement with higher density, mixed pine and hardwood stands that suppress understory development and limit application of prescribed fire. To increase understanding of limiting factors and identify potential approaches for restoring longleaf pine woodlands, we studied initial availability of light and soil water and 2-year (2018–2019) plant community responses after controlling overstory hardwoods in five remnant longleaf pine woodlands having no evidence of previous agriculture at the Savannah River Site near Aiken, SC, USA. Seven hardwood control treatments and a non-treated check were compared in a randomized compete block experiment: cutting, cutting + shredding of logging residues, stem injection with imazapyr herbicide, cutting + basal spray with imazapyr herbicide, cutting + basal spray with triclopyr herbicide, cutting + directed foliar spray with a mixture of glyphosate and imazapyr herbicides, and cutting + broadcast foliar spray with the same herbicide mixture. In the year prior to hardwood cutting (2016), understory light availability averaged 23% of full sun. Throughout the year of treatment installation (2017), average soil water content (SWC) was below permanent wilting point (5.5% SWC) where overstory hardwoods were retained; whereas, it was above wilting point (7.5%) where they had been cut. Thus, combined effects of shade and root competition from overstory hardwoods probably limited cover of herbaceous species in the non-treated check. In the 2 years following treatment, hardwood survival averaged > 99%, 62%, 42% and < 1% for the non-treated check, cutting, shredding, and herbicide treatments, respectively. Relative to the non-treated check, herbaceous species richness was increased by shredding, stem injection, basal spray, or directed foliar treatments; herbaceous cover was increased by basal spray or directed foliar treatments; and woody cover was decreased by directed or broadcast foliar treatments. The directed foliar spray was the most effective treatment for achieving many of the desired understory characteristics of a longleaf pine woodland, including a diverse understory dominated by herbaceous vegetation capable of supporting periodic prescribed fires. Although the imazapyr basal spray treatment increased cover of remnant woodland indicator species, none of the treatments increased richness of this species group, suggesting that restoration of native species composition will be expedited by enrichment seedings or plantings.