Deciduous Research Articles

Quantifying soil erosion and soil organic carbon conservation services in indian forests: A RUSLE-SDR and GIS-based assessment

Indian forests, having sixteen types of vegetation, provide various ecosystem services. Forests reduce water erosion of soil, reduce floods and conserve low river flow during dry seasons. Present study estimated annual sedimentation, texture, soil organic carbon control service of forests of India using the Revised Universal Soil Loss Equation (RUSLE) and Sediment Delivery Ratio (SDR) approach through GIS technique along with identifying important drivers responsible for erosion in forests. The soil erosion control service was based on five factors viz., rainfall erosivity, soil erodibility, slope, crop management, conservation practice factor and SDR across the various forest dominated river basins. Geo-detector modelling was performed to evaluate environmental drivers responsible for soil erosion. Valuation of soil control service of the India’s forests was estimated based on damage and replacement cost method. Annual soil loss rate was maximum in Tropical Thorn Forest and in Ganga River basin. Maximum sediment control and SOC conservation against the soil erosion control service by India’ forests were due to Tropical Dry Deciduous Forest with a total annual sedimentation control and SOC conservation of 33,056,560 tonnes and 3,31,115.06 tonnes, respectively. The conservative estimate of the economic value of soil conservation service by the forests of India was US$ 535.6 M with an average of 4.40 US$ ha−1 and a maximum share of value for Tropical Dry Deciduous Forest i.e. 294.18 million US$ and average maximum value for Littoral and Swamp Forest (28.91 US$ ha−1). The soil erosion in Tropical and Sub-tropical Forest was influenced by the interactive effects between NDVI and Bulk Density. In contrast, soil erosion in the temperate and alpine area was influenced by anthropogenic activity in combination with climatic factors. Present study accounts the role of India’s forests for the soil conservation service and may provide inputs to implement forest and reservoir management strategies besides providing information for Integrated Watershed management and Catchment Treatment Plans.

A case study of nutrient retranslocation in four deciduous tree species of West Bengal tropical forest, India

A case study of nutrient retranslocation in four deciduous tree species of West Bengal tropical forest, India

Assessment of land use and land cover change detection and prediction using deep learning techniques for the southwestern coastal region, Goa, India.

Understanding the connections between human activities and the natural environment depends heavily on information about land use and land cover (LULC) in the form of accurate LULC maps. Environmental monitoring using deep learning (DL) is rapidly growing to preserve a sustainable environment in the long term. For establishing effective policies, regulations, and implementation, DL can be a valuable tool for assessing environmental conditions and natural resources that will positively impact the ecosystem. This paper presents the assessment of land use and land cover change detection (LULCCD) and prediction using DL techniques for the southwestern coastal region, Goa, also known as the tourist destination of India. It consists of three components: (i) change detection (CD), (ii) quantification of LULC changes, and (iii) prediction. A new CD assessment framework, Spatio-Temporal Encoder-Decoder Self Attention Network (STEDSAN), is proposed for the LULCCD process. A dual branch encoder-decoder network is constructed using strided convolution with downsampling for the encoder and transpose convolution with upsampling for the decoder to assess the bitemporal images spatially. The self-attention (SA) mechanism captures the complex global spatial-temporal (ST) interactions between individual pixels over space-time to produce more distinct features. Each branch accepts the LULC map of 2 years as one of its inputs to determine binary and multiclass changes among the bitemporal images. The STEDSAN model determines the patterns, trends, and conversion from one LULC type to another for the assessment period from 2005 to 2018. The binary change maps were also compared with the existing state of the art (SOTA) CD methods, with STEDSAN having an overall accuracy of 94.93%. The prediction was made using an recurrent neural network (RNN) known as long short term memory network (LSTM) for the year 2025. Experiments were conducted to determine area-wise changes in several LULC classes, such as built-up (BU), crops (kharif crop (KC), rabi crop (RC), zaid crop (ZC), double/triple (D/T C)), current fallow (CF), plantation (PL), forests (evergreen forest (EF), deciduous forest (DF), degraded/scurb forest (D/SF) ), littoral swamp (LS), grassland (GL), wasteland (WL), waterbodies max (Wmx), and waterbodies min (Wmn). As per the analysis, over the period of 13 years, there has been a net increase in the amount of BU (1.25%), RC (1.17%), and D/TC( 2.42%) and a net decrease in DF (3.29%) and WL(1.44%) being the most dominant classes being changed. These findings will offer a thorough description of identifying trends in coastal areas that may incorporate methodological hints for future studies. This study will also promote handling the spatial and temporal complexity of remotely sensed data employed in categorizing the coastal LULC of a heterogeneous landscape.

Effect of invasive species on forest composition in tropical dry forest: a case study of invasion by Gliricidia sepium

Ecological concerns caused by biological invasion have been considered an inevitable threat to global sustainability. The superior competitive ability of invasive plant species (IPS) has an impact on vegetation composition and loss of native flora. Recognising IPS at an early stage would significantly contribute to controlling invasive plants, protecting biodiversity and formulating appropriate strategies. Most of the studies available on invasive plants are descriptive and largely confined to non-woody species. The present study focused on the alien Gliricidia sepium, a tree species, to determine the invasive potential of its distribution in tropical dry deciduous forests of Central India. Forty square plots (25 × 25 m) were laid out at each uninvaded and invaded forest to enumerate phytosociological attributes to determine the impact of G. sepium on vegetation composition and community structure. Higher density (37.2 individuals ha−1), basal area (6.32 m2 ha−1) and importance value index (95.8) contributed by G. sepium clearly showed the suppression of seedlings, saplings and trees of native forest species at the invaded sites in terms of species richness, cover and other attributes as compared to at the uninvaded sites. Further, other invasive attributes such as higher seed production, dieback phenomenon, higher coppicing power and higher growth rate as observed during the study clearly affirmed the early speculation that the species might be invasive. The species has a strong potential to spread vigorously and may gradually become invasive throughout the country as already reported from various parts of India. In the present study area, G. sepium was introduced due to restoration and plantation programmes and our findings indicate its negative impact on the native vegetation. Thus, we strongly recommend the avoidance of this species for both plantation and restoration programmes, especially for Indian forests. The study helps in early recognition and rapid monitoring of G. sepium to control its spread throughout the country.

Variation in the timing and duration of autumn leaf phenology among temperate deciduous trees, native shrubs and non-native shrubs.

The timing and duration of autumn leaf phenology marks important transitions in temperate deciduous forests, such as, start of senescence, declining productivity and changing nutrient cycling. Phenological research on temperate deciduous forests typically focuses on upper canopy trees, overlooking the contribution of other plant functional groups like shrubs. Yet shrubs tend to remain green longer than trees, while non-native shrubs, in particular, tend to exhibit an extended growing season that confers a competitive advantage over native shrubs. We monitored leaf senescence and leaf fall (2017-2020) of trees and shrubs (native and non-native) in an urban woodland fragment in Wisconsin, USA. Our findings revealed that, the start of leaf senescence did not differ significantly between vegetation groups, but leaf fall started (DOY 273) two weeks later in shrubs. Non-native shrubs exhibited a considerably delayed start (DOY 262) and end of leaf senescence (DOY 300), with leaf-fall ending (DOY 315) nearly four weeks later than native shrubs and trees. Overall, the duration of the autumn phenological season was longer for non-native shrubs than either native shrubs or trees. Comparison of the timing of spring phenophases with the start and end of leaf senescence revealed that when spring phenology in trees starts later in the season senescence also starts later and ends earlier. The opposite pattern was observed in native shrubs. In conclusion, understanding the contributions of plant functional groups to overall forest phenology requires future investigation to ensure accurate predictions of future ecosystem productivity and help address discrepancies with remote sensing phenometrics.

Phytosociology and Stand Structure of Tropical Dry Deciduous Forest of Dalma Wildlife Sanctuary, Jharkhand, Eastern India

Assessing the composition and structure of ecosystems is of the utmost importance for the conservation of forests. Tree species diversity, distribution pattern and stand structure provide baseline information for conservation and management of the forest. The present study was conducted in the Dalma Wildlife Sanctuary to assess the diversity, composition, richness and stand structure. Standard sampling method was used for vegetation sampling and data collection. An aggregate of 2876 individuals belonging to 41 species, 34 genera and 22 families were identified from 2.5 ha sampling area. The sanctuary recorded tree density of 1151 ind./ha with a total basal area of 510.807 sq. m. Analysis of IVI value revealed that S. robusta (65.207), B. cochinchinensis (22.451), A. latifolia (18.071), T. tomentosa (15.604) and D. melanoxylon (12.449) were the dominant tree species in the sanctuary. The family Fabaceae was the most species-rich family with 9 species. Over 70% of tree species showed contiguous distribution pattern in the studied area. The sanctuary recorded diversity index (H') of 3.204, richness index (R') of 4.504 and evenness index (E) of 0.863. The stand structure indicates a natural satisfactory regeneration and healthy population in the studied forest areas. Density-girth class distribution showed that more than 75% of the total population was dominated by seedlings and saplings. The research findings suggests that the sanctuary is an ecolologically rich site with an expanding population. An efffective management and conservation strategy will ensure a sustained biodiversity and richness of this protected site.

Palaeoenvironmental reconstruction of poorly stratified sites using malacological assemblages of archaeological features: A case study in Reims (NE France)

At the 53 ter rue de Louvois, in Reims, a number of human settlements dating from the Mesolithic period to the Early Middle Ages have been uncovered. Located on a footslope, these successive settlements are evidenced by archaeological features such as pits and ditches, which broadly appear at the same stratigraphic level. These features of different ages therefore provide valuable opportunities for sedimentary records in a context where natural stratification is poor. The examination of sedimentary archives sourced from archaeological features reveals distinct environmental phases interspersed with hiatuses stemming from the intermittent human habitation of the site. The initial phase provides insights into the early Holocene period, particularly during the First Mesolithic, illustrating the emergence of a pioneering semi-forest environment between around 9200 and 8200 cal. BC. Subsequently, Phase 2a, dated between 7050 and 6250 cal. BC, witnesses the expansion of deciduous forests during the Second Mesolithic. This expansion peaks during the Middle Neolithic (4300–3500 cal. BC), despite the construction of an enclosure in Phase 2b. The site is later cleared, at an unknown date between the end of the Middle Neolithic and the beginning of the Iron Age, probably during the late Bronze Age, between 1300 and 800 cal. BC. Phase 3 is thus characterised by the dominance of a dry grassland environment from the Hallstatt period through the early Middle Ages. This regional example illustrates the remarkable potential of malacological remains for reconstructing palaeoenvironments in poorly stratified contexts, as close as possible to human settlements and outside wetlands, the main sites for palynological investigations.

Leaf Spot Disease of Michelia alba caused by Alternaria alternata in China.

The perennial deciduous tree Michelia alba is a widely cultivated street plant in China. In June 2021 and March 2022, M. alba trees with leaf spots were found in the green belt of the approximately 200,000 m2 community (32.62°N, 116.98°E) of Tianjia'an District, Huainan, Anhui, China, where approximately half of the M. alba trees had brown leaf spots surrounded with irregular yellow halos ranging from 2 to 6 mm in diameter (Fig S1A). The leaves of M. alba trees with multiple lesions became blighted. To isolate the potential pathogens causing leaf spot symptoms in M. alba trees, twenty fragments (2 cm2) were excised from the margin of the necrosis on symptomatic leaves, immersed in 1% sodium hypochlorite for 45 s, and then washed three times in sterile water. The fragments were plated and incubated on potato dextrose agar (PDA) at 25 °C and 15 dark green fungal colonies were obtained 5 days later. Single-spore isolates of the fungal colonies plated on potato carrot agar (PCA, Simmons 2007) produced gray, floccose colonies, which reached 71 mm after 7 days at 25 °C were obtained 5 days later (Fig S1C). Optical microscopy analysis showed that single-spore isolates formed sparsely branched chains with pale brown conidiophores on PCA after incubation at 25 °C in darkness for 7 days. The conidia were ellipsoidal, inverted rod, or ovoid, light brown, and 10.0 to 52.5 × 4.5 to 22.7 μm, with zero to four longitudinal or oblique and zero to eight transverse septa (n = 50). Partial conidia are 2.5 to 27.5 × 0.6 to 3.7 μm with cylindrical light brown beaks (n = 50) (Fig S1D, E). The cultural and morphological characteristics of the isolated fungi were consistent with the description of Alternaria alternata (Woudenberg et al. 2015). To further characterize the isolated fungi, the genomic DNA of three representative strains (BYL-1, BYL-2 and BYL-3) were extracted from their mycelia, respectively. ITS region and housekeeping genes GPD, and TEF, were amplified and sequenced using ITS4/ITS5 (White et al. 1990), Gpd1/Gpd2 (Berbee et al. 1999), and EF1-728F/EF1-986R (Carbone and Kohn 1999), primer pairs, respectively. BLAST analysis showed that the isolates BYL-1 (GenBank accession nos. OP325693, OP405008, and OP405009), BYL-2 (GenBank accession nos. PP057859, PP138442, and PP138444), and BYL-3 (GenBank accession nos. PP057860, PP138443, and PP138445) shared 99 to 100% identity with Alternaria alternata (GenBank accession nos. AF347032.1, AY278809.1, KC584693.1), which suggested that all the three isolates belong to A. alternata. The identifications were further confirmed by phylogenetic analysis based on combined DNA sequences data of ITS, GPD, and TEF. As showed in Fig S2, the strains of BYL-1 , BYL-2 and BYL-3 formed a robust clade with A. alternata CBS918.96. Taken together, the morphology and molecular assays suggest that strain BYL-1 is A. alternata. To test pathogenicity, the isolate BYL-1 was cultured on PCA for 7 days to prepare conidial suspensions, and the spore concentration was adjust to a final concentration of 105 spores/ml. The leaves of 3-5-leaf stage of six 5-years-old natural planting M. alba plants were sprayed with conidial suspensions and sterile distilled water, respectively. The petiole of each inoculated leaves of M. alba were secured with sterile wet cotton, and covered with plastic bags to prevent moisture evaporation after incubation. After a 3- to 5- day of inoculation, necrotic lesions appeared on the leaves inoculated with conidial suspensions, whereas no necrotic lesion was observed in the control leaves inoculated with sterile distilled water (Fig S1B). To fulfill the Koch,s postulates, fungi were re-isolated from the margin of necrotic lesions and identified as A. alternata by DNA sequencing the ITS gene. To our knowledge, this is the first report of A. alternata causing leaf spot on M. alba. Because the disease could cause damage to the foliage influencing the greening and ornamental effects of these trees, control measures may need to be implemented during daily management.

Spatiotemporal characteristics of Net Ecosystem Exchange in the Beijing-Tianjin sand source region and its response to drought

In the context of global change, the carbon budget in arid and semi-arid regions have changed significantly. Understanding these dynamic features and their response to climate change is essential for regional carbon cycle assessments. The Beijing-Tianjin Sand Source Region (BTSSR), a significant ecological project in China, is central to studies on carbon budget dynamics. While global change intensifies, understanding its carbon budget response to drought is crucial. By integrating data from the Net Ecosystem Exchange (NEE) and the Standardized Precipitation Evapotranspiration Index (SPEI), we analyzed the spatiotemporal attributes of NEE in this region and its response to drought. The BTSSR is currently in a carbon sink state, with the mean NEE being −45.13 gCm−2 and a rate of change at −0.005 gCm−2a-1. The maximum carbon sink occurs during the summer, whereas the winter is characterized by a net release of carbon to the atmosphere. In terms of spatial variation, the NEE shifts from positive to negative from southeast to northwest across the region. The impact of drought on summer NEE is notably significant, with the correlation and sensitivity being −0.717 (p < 0.05) and −3.911, respectively. As drought intensity increases, NEE changes from negative to positive, transforming BTSSR into a carbon source. NEE responded most significantly to strong drought and was less affected by light drought. The NEE of BTSSR showed a significant short-term response to drought, with a lag of 1–4 months. Considering different vegetation types, the temperate desert’s NEE is most significantly affected by drought and is the most sensitive, with correlation and sensitivity values of −0.841 (p < 0.05) and −12.570, respectively. In contrast, the warm temperate deciduous broadleaf forest shows stronger resistance to drought. This study elucidates how the carbon budget of different vegetation types in a typical ecological engineering area changes under the background of climate change and human activities, and contributes to the understanding of the impacts of drought events on the carbon cycle of different vegetation types, as well as the response of the latter to the former, especially the lagged response. It provides different perspectives for the subsequent ecological engineering construction.

Genome-Wide Identification and Expression Profile Analysis of the Phenylalanine Ammonia-Lyase Gene Family in Hevea brasiliensis.

The majority of the world's natural rubber comes from the rubber tree (Hevea brasiliensis). As a key enzyme for synthesizing phenylpropanoid compounds, phenylalanine ammonia-lyase (PAL) has a critical role in plant satisfactory growth and environmental adaptation. To clarify the characteristics of rubber tree PAL family genes, a genome-wide characterization of rubber tree PALs was conducted in this study. Eight PAL genes (HbPAL1-HbPAL8), which spread over chromosomes 3, 7, 8, 10, 12, 13, 14, 16, and 18, were found to be present in the genome of H. brasiliensis. Phylogenetic analysis classified HbPALs into groups I and II, and the group I HbPALs (HbPAL1-HbPAL6) displayed similar conserved motif compositions and gene architectures. Tissue expression patterns of HbPALs quantified by quantitative real-time PCR (qPCR) proved that distinct HbPALs exhibited varying tissue expression patterns. The HbPAL promoters contained a plethora of cis-acting elements that responded to hormones and stress, and the qPCR analysis demonstrated that abiotic stressors like cold, drought, salt, and H2O2-induced oxidative stress, as well as hormones like salicylic acid, abscisic acid, ethylene, and methyl jasmonate, controlled the expression of HbPALs. The majority of HbPALs were also regulated by powdery mildew, anthracnose, and Corynespora leaf fall disease infection. In addition, HbPAL1, HbPAL4, and HbPAL7 were significantly up-regulated in the bark of tapping panel dryness rubber trees relative to that of healthy trees. Our results provide a thorough comprehension of the characteristics of HbPAL genes and set the groundwork for further investigation of the biological functions of HbPALs in rubber trees.

Effects of Leaf Species and Conditioning State of Fresh Leaves on Colonization by Stream and Pond Macroinvertebrates

Fresh, green leaves are increasing as resources in aquatic ecosystems due to more frequent severe spring and summer storms, but research on allochthonous resources typically uses senescent leaves. We examined macroinvertebrate colonization of green leaves of three native deciduous trees (red maple, red oak, and tulip poplar) over two weeks within both a stream and fishless pond. Leaf colonization varied depending on the taxa of leaves and colonizers, submersion time, and the ecosystem examined. Within the stream, the densities of isopods (Lirceus sp.) and snails (mostly the invasive Potamopyrgus antipodarum) did not vary significantly across leaf species. In contrast, mayflies (Tricorythodes sp.) in the stream colonized tulip poplar in greater numbers than red oak leaves, while higher densities of planarians (order Tricladida) occurred within red oak leaves. The numbers of mayflies and snails decreased significantly by the second week, but the densities of isopods and planaria within stream leaf packs were consistent. In contrast, within the pond, significantly more isopods (Caecidotea communis) were collected after the first than after the second week of submersion and in tulip poplar leaves. Clams (Sphaeriidae) in the pond, on the other hand, were more prevalent in the second week but did not discriminate among leaf species. While the number of leeches (mostly Helobdella stagnalis) was consistent across weeks, significantly fewer leeches resided within tulip poplar leaves than within red oak leaves. Our results suggest that there are no consistent colonization-preference rankings of species of fresh leaves across freshwater benthic macroinvertebrate taxa. Even within a functional feeding group (e.g., the two types of isopods and snails, all detritivore-herbivores), there were differences in colonization patterns. Therefore, increased allochthonous inputs of fresh leaf litter due to severe spring- and summer-time storms are likely to promote the populations of various taxa to different extents.

Root Respiration–Trait Relationships Are Influenced by Leaf Habit in Tropical Plants

Root respiration is a critical physiological trait that significantly influences root system activity. Recent studies have associated root respiration with the economic functioning of roots; however, research on root respiration in tropical plants remains limited. This study examined the fine root respiration and the relationship between root respiration and root chemical and morphological traits in 16 tropical plant species, including both evergreen and deciduous species. Findings revealed that deciduous species exhibited higher root respiration compared to evergreen species. Root respiration positively correlated with root nitrogen concentration and specific root length and correlated negatively with root diameter and root tissue density across all species. The root respiration patterns in evergreen species aligned with those seen in all tree species, while deciduous species showed a distinct negative correlation with root tissue density and no significant correlations with other root traits. Principal component analysis revealed that the patterns of root variation in both evergreen and deciduous trees were multidimensional, with deciduous trees exhibiting acquisitive traits and evergreen trees displaying conservative traits. Random forest and multiple regression analysis showed that specific root length exerted the most significant influence on root respiration in both evergreen and deciduous trees. These findings are ecologically significant, enhancing our understanding of root respiration in tropical plants and its impact on ecosystem functions. They contribute valuable insights and support the conservation and management of tropical vegetation.

Phenological mismatch between trees and wildflowers: Reconciling divergent findings in two recent analyses

Abstract Recent evidence suggests that community science and herbarium datasets yield similar estimates of species' phenological sensitivities to temperature. Despite this, two recent studies by Alecrim et al. (2023) and Miller et al. (2022) found very different results when using different data sources (community science and herbarium specimens, respectively) to investigate whether warming threatens wildflowers with phenological mismatch in relation to shading by deciduous trees. Here, we investigated whether differences between the two studies' results could be reconciled by testing four hypotheses related to model design, species, spatiotemporal data extent and phenophase. Hybrid model structures brought results from the two datasets closer together but did not fully reconcile the differences between the studies. Neither the species nor the phenophase selected for analysis seemed to be responsible for differences in results. Cropping the datasets to match spatial and temporal extents appeared to reconcile most differences but only at the cost of much higher uncertainty associated with reduced sample size. Synthesis: Our analysis suggests that although species‐level estimates of phenological sensitivity may be similar between community science and herbarium datasets, inherent differences in the types and extent of data may lead to contradictory inference about complex biotic interactions. We conclude that, until community science data repositories expand to match the range of climate conditions present in herbarium collections or until herbarium collections match the spatial extent and temporal frequency of community science repositories, ecological studies should ideally be evaluated using both datasets to test the possibility of biased results from either.

Analysis of spatio-temporal changes in net primary productivity and their driving factors in ecological functional areas of the Yellow River Basin

The Yellow River Basin (YRB) is an important region for both ecological and economic growth in China, and a healthy and stable ecological environment is fundamental to achieving high-quality development. Investigating the spatio-temporal changs of vegetation carbon sinks in the YRB is necessary to improve understanding of the regional carbon cycle. This study analyzed the YRB using the Google Earth Engine (GEE) platform. The basin was divided into sections based on ecological function regionalization schemes. We applied Theil-Sen median trend analysis and Spearman correlation analysis, along with the lasso regression model, to examine the NPP's temporal and spatial patterns and its driving factors in these regions. The objective was to examine the NPP’ s temporal and spatial patterns and its driving factors in these regions, identifying commonalities within regions and differences between regions, while analyzing in a targeted manner the lack of vegetation carbon sequestration in ecological areas. This study highlighted the importance of ecological engineering in ecological civilization and carbon neutrality, providing scientific theoretical support and a decision-making basis for the realization of carbon neutrality. The research results indicate significant upward trends (p<0.001) in both the average annual NPP (AANPP) growth rate (57.98%) and the total annual NPP (TANPP) growth rate (41.9%) in the YRB from 2001 to 2020. The multi-year average NPP (MYANPP) exhibit a spatial distribution with high values in the south and low values in the north. The spatial distribution of NPP exhibits notable spatial aggregation and heterogeneity, where regions demonstrating improvement trends constitute 93.01% of the area, and approximately 79.73% of this region displays low volatility. A high-value area is concentrated in the Agroecological Zone of the Fenwei Basin (I-11), the Loess Plateau Agriculture and Grassland Ecological Zone (I-12), and the Qinba Mountains Deciduous and Evergreen Broad-leaved Forest Ecological Zone (I-15), with significant spatial differences. Temperature, precipitation, and forests are the foremost elements affecting NPP in the YRB, exhibiting positive correlations. Conversely, farmland displays negative correlations. Overall, NPP shows an increasing trend in all ecological function areas, and the NPP of the YRB shows a trend of improvement as a whole, as the ecological environment of the YRB has improved significantly.

Water use and mortality risk of four tropical canopy trees with different leaf phenology during the 2016 El Niño drought

The physiological response of plants to water stresses has been a focus in understanding plant-atmosphere feedback. Tropical forests are particularly noteworthy for their remarkable diversity and dynamics. However, a deep understanding of physiological response and associated mortality risk of tropical trees with different leaf phenology under drought is still deficient. In this study, we combined sap flow measurements and a plant hydraulic model to present the water utilization of four canopy trees (two deciduous trees and two evergreen trees) in a Panamanian seasonal tropical forest during the 2016 El Niño drought. The results showed that the transpiration (Td) of deciduous trees rapidly decreased with intensifying soil drought during the dry season, while evergreen trees still maintained high Td and increased with the increase of atmospheric dryness (vapor pressure deficit (VPD)). During the wet season, the Td of both deciduous and evergreen trees was jointly driven by increasing soil moisture (SWC) and reducing VPD. The differential Td pattern during the dry season is closely related to the difference in leaf phenology, with deciduous trees greatly reducing canopy stomatal conductance (Gs) through defoliation, and thereby maintaining leaf water potential (Ψl) and reducing water loss. Additionally, deciduous trees demonstrated a slow increase in the difference between midday (Ψl,md) and predawn (Ψl,pd) leaf water potential (i.e. lower hydraulic sensitivity (σ)) compared to evergreen trees. Evaluation of mortality risk under changing water stresses further indicated that all trees exhibited high hydraulic failure risk (HFR) under decreasing SWC scenarios. Moreover, deciduous trees displayed a much higher stomatal closure risk (SCR) than evergreen trees. These differences in Gs response and σ suggest a key role of the coordination between stomatal regulation and plant hydraulics in mediating physiological response to water stresses. More investigation and mechanism illumination will facilitate the prediction of tropical forest response to drought.

Seedlings growth from different age of rubber trees (Hevea brasiliensis Muell. Arg.) experiencing repeated leaf fall

The budding technique propagation requires rootstock, which are raised from rubber seeds. Due to repeated leaf fall disease since 2015, seed production dropped and threatened the rubber-replanting program. Amid this situation, young trees may be a temporary source of the seeds for rootstocks, which under normal conditions is not recommended. To test this hypothesis, a comparison of germination rate, seedling growth, and biomass accumulation of the seeds from young and mature PB 260 rubber trees was carried out at Sungei Putih Research Unit, Indonesian Rubber Research Institute, North Sumatra, Indonesia. The study showed that the germination rate of the seeds was low i.e. 7.23 + 2.96 % of young plants and 21.96 + 13.51 % of mature plants respectively, both were below normal values around 70 – 80%. After germination, no significant difference was found in the growth of seedlings from young trees and their mature counterparts. The root/shoot ratio exhibited no significant difference between the two types of seedlings observed, indicating a similar biomass accumulation capability. In the condition when seed supply was limited due to leaf fall disease, the seeds of young trees might be used as a temporary source with standard selection protocols should be implied.

Should the relationship between leaf margin and temperature be re‐defined for areas with colder climates?

AbstractAimThe well‐proven positive correlation between the increased proportion of entire‐leaved woody dicotyledonous species and increased mean annual temperature has been commonly used to estimate temperature in the past. However, in regions of colder climates, this relationship is not straightforward, questioning the accuracy of temperature estimation.LocationFinland, Poland, Germany.TaxonDicotyledons.MethodsThe floristic composition of 10 × 10 km squares in 20 km wide transects through Finland, Poland and Germany was analysed.ResultsAt higher temperatures, deciduous woody plants appeared to show the expected positive relationship between mean annual temperature and the proportion of entire leaf margins. However, we found a negative correlation within woody deciduous plants at higher latitudes with mean annual temperature values from approximately −2.5°C to +2–4°C and at all temperatures when all woody plants were included. Herbaceous species showed a weak relationship between morphology and temperature.Main ConclusionsThe hypothesis that the phenomenon was caused by a large percentage of entire‐leaved evergreen species that winter under snow cover was rejected. These results indicate that using the leaf margin analysis method for past temperature estimation is increasingly inaccurate at colder temperatures. Consequently, we recommend avoiding this method at locations where the mean annual temperature falls below 5°C.

Tree species-specific differences in carbon allocation to ectomycorrhizal symbionts tightly relate to ectomycorrhizal fungal community composition

Host trees allocate photosynthates to ectomycorrhizal symbionts (ECMs) in exchange for soil nutrients, and the carbon allocation has profound effects on forest carbon sequestration. However, it is still a challenge to precisely quantify the amount of carbon allocated to ECMs and to identify factors affecting this allocation. Here, we estimated tree species-specific differences and the dynamics of carbon allocation to ECMs by 13CO2 labeling along seedling development, and explored mechanisms underlying these differences from the perspective of ECM fungal community across four tree species (evergreen Picea asperata and Quercus aquifolioides, deciduous Larix gmelinii and Betula albosinensis) and three development stages (early, middle and late of the growing season). Results showed that the proportion of 13C allocated to ECMs (P13CECMs) and ECM fungal community composition varied across tree species and seedling development. P13CECMs was higher in deciduous (3.3 ± 0.7%) trees than in evergreen trees (1.6 ± 0.3%), and higher at the late (5.2 ± 0.7%) than middle (1.8 ± 0.3%) and early (0.3 ± 0.1%) growing season. The relative abundance of the four ECM exploration types (contact, short-, medium- and long-distance) was 7.8–14.8%, nearly 50%, 25.2–31.2%, and nearly 10%, respectively, and varied significantly for contact and medium-distance types. The relative abundance of contact type was higher in deciduous than evergreen trees, and higher at the late than mid-growing stage, but the opposite was true for medium-distance type. Across tree species and seedling development, P13CECMs was positively correlated with the relative abundance of contact type, but negatively correlated with that of medium-distance type. The results suggest that carbon allocation to ECMs is tightly associated with ECM fungal community composition and highlight the critical role of ECM fungal community composition in carbon budges of forest ecosystem.

Influence of Clear Felling on СО2 Emission from Surface of Podzolic Soil of Coniferous–Deciduous Forest (Middle Taiga, Komi Republic)

Influence of Clear Felling on СО2 Emission from Surface of Podzolic Soil of Coniferous–Deciduous Forest (Middle Taiga, Komi Republic)

Combining new rootstocks and training systems for sustainable production in deciduous tree crops

Combining new rootstocks and training systems for sustainable production in deciduous tree crops