Growth and Influencing Factors of Three Native Tree Species in Coastal Casuarina equisetifolia Plantation

[Objective] The aim was to study the growth and environment factors of three native tree species（Thespesia lampas,Calophyllum inophyllum and Hernandia sonora）in Hainan in coastal Casuarina equisetifolia plantation.[Method] The coastal sandy soil was treated by adding wood chips,bagasse and the control without adding anything in the plant pits.The growth of three native tree species planted for one year was analyzed.[Result] ① One year later,the survival rate showed an order of T.lampasH.sonoraC.inophyllum;the net increase of basal diameter showed an order of H.sonoraT.lampasC.inophyllum;while the net increase of plant height showed an order of T.lampasC.inophyllumH.sonora.The difference of survival rate between T.lampas and C.inophyllum was extremely significant,the difference of survival rate between H.sonora and C.inophyllum was significant,but the survival rate between T.lampas and H.sonora showed no significant difference.The difference on net growth of plant height among T.lampas,C.inophyllum and H.sonora was extremely significant,and the different on the net growth of basal diameter between T.lampas and C.inophyllum was significant.② Among different soil treatments,the survival rate of three native tree species in the treatment by adding wood chips,bagasse were higher than the treatment without adding anything,and the difference of survival rate of T.lampas between the treatment by adding wood chips,bagasse and the treatment without adding anything was extremely significant,but the treatment by adding wood chips and bagasse had not significant difference.③ The growth of three native tree species showed some correlation with environment factors（∣r∣0.3）.The survival rate of T.lampas showed higher correlation with soil pH value and soil moisture,and the basal diameter and height of T.lampas showed some correlation with soil pH value and soil temperature.The survival rate of C.inophyllum showed higher correlation with soil pH value,soil temperature and light intensity,while the basal diameter and height of C.inophyllum showed some correlation with soil temperature.The survival rate of H.sonora showed higher correlation with soil salinity and soil temperature,while the basal diameter and height of H.sonora showed some correlation with soil temperature.The basal diameter and height of three native tree species had higher correlation（r0.5）,which had reached a significant level.[Conclusion] In the one-year growth period in C.equisetifolia forest,the native tree species of T.lampas grew best and it was the most potential forest species mixed with C.equisetifolia.

Responses of Native Tree Species to Soil Water Stress in a Tropical Forest on Limestone,Vietnam

Forests over limestone in the tropics have received little attention and limestone forests in Vietnam have been overlooked to an even greater extent in terms of tree physiology. In Ba Be National Park, Vietnam, soil water availability in limestone forests seems to be the most limiting factor in the dry season. Therefore, in order to enhance the preliminary knowledge of choosing native tree species for enrichment planting in the restoration zone, characteristics of the 20 native tree species to soil water stress were investigated in a limestone forest. One-ha plot each consisting of twenty-five 20 m × 20 m plots was established in undisturbed forests. All trees ≥ 10 cm DBH were measured in 20 m × 20 m plots, while twenty-five 5 m × 5 m subplots were established in order to sample the regeneration of tree species with a DBH < 10 cm. The Scholander apparatus and freezing point osmometry were used in order to measure the leaf water potential (Ψw) and leaf osmotic potential (Ψπ) of the 20 native tree species, respectively in this study. 61 species belonging to 34 families of all trees with a DBH ≥ 10 cm were recorded in one ha, while 31 species representing 18 families of trees < 10 cm DBH were identified in 625 m2. The 20 species’ leaf water and osmotic potential values revealed significant differences among species. The maximum leaf water potential was not affected by any anticipated sources of variation, while the minimum water potential, however, showed significant variation to soil water stress. The results in the study area emphasized the importance of water factors in influencing tree species distribution;it could be concluded that native species with wide water potential ranges would be better able to withstand water changes and might be thus good candidates for reforestation (enrichment planting) in limestone areas.

Propagation of Grevillea banksfi Affects the Dynamic of Mycorrhizal Fungi Communities Associated with Native Tree Species of Madagascar

Propagation of exotic plant species is found in many regions of Madagascar Island. This work aims to describe the impacts of the propagation of Grevillea banksii on soil microbial activities and on the regeneration of two native tree species （Intsia bij＇uga and Dalbergia trichocarpa） in the eastern part of Madagascar. The study was conducted within Ianjomara forest where some types of the vegetation are observed such as an area characterized by grassland （P 1）, by homogeneous population of G. banksii （P2） and by a natural forest composed mainly of L bijuga or D. trichocarpa （P3 and P4）. Structure of mycorrhizal fungi communities and associated microorganisms were described on soils from each study plot. The development of I. b^juga and 1）. trichocarpa, was evaluated 4 months after planting on P1, P2, P3, P4 soils formerly colonized by G. banksii. According to the nutrients availability on each soil type, the development of G. banksii was accompanied or not by a high formation of cluster roots. The authors＇ results also show that soil occupied by G. banksii decreased the global microbial and phosphatase activities of soil especially on soil within a high density of cluster roots. Moderately mycotrophic, G. banksii disturbs the structure and the dynamics of symbiotic microflora such as endomycorrhizal fungi （MA） and rhizobia associated with the two native tree species. The findings illustrate the negative impact of G. banksii propagation on the regeneration and the conservation of native tree species in Madagascarian forest.

Resilience and response:Unveiling the impacts of extreme droughts on forests through integrated dendrochronological and remote sensing analyses

Extreme droughts are anticipated to have detrimental impacts on forest ecosystems,especially in water-limited regions,due to the influence of climate change.However,considerable uncertainty remains regarding the patterns in species-specific responses to extreme droughts.Here,we conducted a study integrating dendrochronology and remote sensing methods to investigate the mosaic-distributed maple-oak(native)natural forests and poplar plantations(introduced)in the Horqin Sandy Land,Northeast China.We assessed the impacts of extreme droughts on tree performances by measuring interannual variations in radial growth and vegetation index.The results showed that precipitation and self-calibrated palmer drought severity index(scPDSI)are the major factors influencing tree-ring width index(RWI)and normalized difference vegetation index(NDVI).The severe droughts between 2000 and 2004 resulted in reduced RWI in the three studied tree species as well as led to NDVI reductions in both the maple-oak natural forests and the poplar plantations.The RWI reached the nadir during the2000-2004 severe droughts and remained at low levels two years after the severe drought,creating a legacy effect.In contrast to the lack of significant correlation between RWI and scPDSI,NDVI exhibited a significant positive correlation with scPDSI indicating the greater sensitivity of canopy performance to droughts than radial growth.Furthermore,interspecific differences in RWI and NDVI responses were observed,with the fast-growing poplar species experiencing a more significant RWI decrease and more negative NDVI anomaly during severe droughts than native species,highlighting the species-specific trade-offs between drought resilience and growth rate.This study emphasizes the importance of combining tree-level radial growth with landscape-scale canopy remote sensing to understand forest resilience and response.Our study improves our understanding of forest responses to extreme drought and highlights species differences in climate responses,offering crucial insights for optimizing species selection in sustainable afforestation and forest management in water-limited regions under the influence of climate change.

Diametric Structure of One Fragment of One Deciduous Seasonal Forest in Brazilian Savanna Eco Museum

A 10 ha deciduous seasonal forest fragment (15°45'54''S and 49°04'03''W) found in the bioregion of the Savanna Eco Museum localized in the state of Goiás, Brazil was studied. For the phytosociological survey, 10 sample plots of 20 × 20 m were systematically located. All living trees of 5 cm DBH and above were measured with the plot boundaries. There were 742 individuals belonging to 83 species and 38 families. The richest families in terms of the number of species were Leguminosae, Rubiaceae, Myrtaceae, Apocynaceae and Chrisobalanaceae, which contributed 48% of the total species. The species with the highest importance value indices (IVI) were Tapira quianensis (Aubl.), Protium heptaphyllum (Aubl.) March., Callisthene mayor (Mart.), Amaioua guianensis (Aubl.) and Anadenanthera macrocarpa (Benth.) Brenan. The Shannon diversity index was 3.80 nats/individuals and the Pielou equality index was 0.86 for the total population. 549 sampled trees had DBH values lower than 30 cm. This indicates that this forest has a high potential for natural succession. Two DBH distributions were observed: the typical reverse “J”, described frequently in the literature, and a nearly Gaussian distribution.

Eutrophication Process of Soil nearby a Sanitary Landfill and Its Influence on Brazilian Savanna Vegetation

This work aimed to demonstrate if exists a relation between eutrophic processes of soil (N, P, K, pH, and organic matter) with phytosociology mosaic of native tree species in Brazilian adjacent sanitary landfill areas of the savanna. One of the study area is located in Brasilia, Federal District, and the other one in Goiania, State of Goiás, 210 km far each other. The methodology consisted in techniques, procedures and specific software applied to this kind of data. There were used plots and subplots for each area and for the vegetation and soil survey. Statistical significance showed that there exists a relationship between eutrophic processes of soil with phytosociology mosaic of native savanna tree species.