Himalayan Forests Research Articles

Ecosystem carbon storage, allocation and carbon credit values of major forest types in the central Himalaya

Himalayan forests are crucial global carbon reservoirs that contribute significantly to carbon mitigation efforts. Although situated within a single climatic zone, Himalayan forests include diverse forest types within a short distance due to variations in altitude, mountain range, slope, and aspect. This study aimed to estimate ecosystem carbon storage (including plant biomass, deadwood, litter, and soil organic carbon [SOC]) and allocation and to evaluate carbon sequestration and carbon credit potential in chir-pine plants (Pinus roxburghii Sarg.), deodar (Cedrus deodara [Roxb.] G. Don), oak (Quercus leucotrichophora A. Camus), and sal (Shorea robusta [Roth]) forests in the central Himalaya. Volumetric equations were utilized across diverse tree species and supplemented by field sampling, particularly by employing the quadrat method to quantify tree biomass. The carbon stocks within ecosystems varied considerably, ranging between 122.44 and 306.44 Mg C ha−1, with discernible differences among forest types, with oak forests exhibiting the highest carbon stock, followed by deodar and sal forests, and pine forests showing the lowest. The allocation of ecosystem carbon stocks among the different components, including trees (21%–34%), soil (64%–77%), deadwood (0.9%–0.35%), and litter (0.46%–1.20%), demonstrated significant variability. The Mantel test revealed the significant influence of environmental factors on carbon storage. Carbon dioxide (CO2) sequestration ranged from 448.98 (pine forest) to 1123.16 (oak forest) Mg CO2 ha−1, while carbon credit values ranged from 1346.96 EUR ha−1 (pine forests) to 3379.49 EUR ha−1 (oak forest). In this study, dominant trees in various forest types contributed to higher carbon storage in their biomass and forest soil, resulting in greater carbon credits. The present research evaluated ecosystem carbon storage, CO2 sequestration potential, and carbon credit valuation for major forests in the central Himalaya. By incorporating these findings into forest management plans and strategies, the carbon sequestration potential and carbon trading of the central Himalayan forest ecosystem in India can be enhanced.

Diversity and Plant Growth-Promoting Activities of Culturable Seed Endophytes in Abies pindrow (Royle ex D. Don) Royle: Their Role in Seed Germination and Seedling Growth.

Abies pindrow, a vital conifer in the Kashmir Himalayan forests, faces threats from low regeneration rates, deforestation, grazing, and climate change, highlighting the urgency for restoration efforts. In this context, we investigated the diversity of potential culturable seed endophytes in A. pindrow, assessed their plant growth-promoting (PGP) activities, and their impact on seed germination and seedling growth. We cultured 729 microbial isolates that were resolved into 30 bacterial and 18 fungal species across various phyla. All 48 isolates exhibited various PGP activities. Specifically, all the cultured isolates showed IAA activity with concentrations ranging from 2.07 to 8.453μg/ml, while ammonia production ranged from 0.936 to 3.436mM/ml. Only 18 isolates, predominantly fungi, tested positive for phosphate solubilisation. Additionally, 20 isolates exhibited the ability to inhibit the growth of Fusarium oxysporum f.sp. pini. We selected four bacterial and six fungal isolates, which showed positive results for all PGP activities, to evaluate their effects on seed germination and seedling growth. Notably, seed germination rates increased by 750.9% under bacterial and consortium treatments and by 550.45% under fungal treatment. The consortium treatment also led to a 96% increase in needle count, while bacterial treatment enhanced stem length by 55.4%. Furthermore, shoot biomass also showed a significant increase with both bacterial and fungal treatments, underscoring the potential of harnessing seed endophytes to boost A. pindrow seedling health and resilience. This study underscores the crucial role of seed endophytic diversity in enhancing seed germination, seedling growth, and forest restoration efforts.

Nitrogen and Metal Ions Accumulation in Two Sensitive Himalayan Lichens From Western Nepal: A Reference for Ecosystem Health Monitoring

In this study, thalli nitrogen (N) and metal ions contents in the two fruticose lichens (Ramalina intermedia and Usnea cornuta) were quantified, which were collected from a pristine Himalayan forest of Shey Phoksundo National Park of western Nepal. Besides, the probable impacts of N and metal ions in physicochemical responses such as electrical conductivity, chlorophyll contents, and chlorophyll degradation were studied. Our initial hypothesis was there are considerable amounts of thallus N and metal ions in lichens from the study area, and it has substantial impacts on physicochemical responses. In comparison, the thalli N concentration was observed to be the greatest in R. intermedia thalli (0.24%–1.15%). However, comparable amounts of metal ions in both lichen species were observed. Regression analysis revealed the least or no impacts of N and metal ions in physicochemical responses. The principal component analysis suggests the contribution of different environmental variable and their correlation with lichen’s variables. This study provides evidence of the least concentration of N and metal ions and only minor impacts on the physicochemical integrity of the two sensitive lichens in our study area. This study is likely to contribute as field‐based reference information for further studies on the species‐specific N and metal ions accumulation in lichens from different Himalayan forest systems to monitor ecosystem health.

Shifts in the ecological drivers influence the response of tree and soil carbon dynamics in central Himalayan forests.

Understanding and regulating global carbon relies crucially on comprehending the components and services of forest ecosystems. In particular, interactions that govern carbon storage in trees, soil, and microbes, driven by factors like vegetation structure, function, and soil characteristics, remain poorly understood, especially in the central Himalayas. To address this gap, we investigated carbon storage in tree aboveground biomass, root biomass, and soil across different vegetation types. We also examined how vegetation parameters {vegetation diversity (H'), diameter at breast height (DBH), basal area (BA), and biomass}, and soil characteristics {bulk density (BD), moisture (Mo), pH, and total nitrogen (N)} might influence forest carbon storage. Our study, based on 14 plots (0.1ha each) spanning four distinct vegetation types {Sal forest (SF, 3), Chir-pine forest (PF, 4), Nepalese-alder forest (AF, 3), and Banj-oak forest (OF, 4)} in the central Himalaya, revealed several key insights. Tree carbon storage ranged from ∼79 to 261MgC ha-1, accounting for 41-65% of forest carbon storage, while soil carbon storage ranged from ∼28 to 69MgC ha-1, contributing 35-58%. These values varied with vegetation types and were influenced by the vegetation and soil characteristics associated with each forest type. Important contributors to tree and soil carbon storage included soil Mo, N, and vegetation structural diversity (H', BA), explaining 8-64 % of the variation. Path analysis indicated that increased vegetation diversity, soil properties, and conservative traits (fine roots and leaves) strongly influence tree and soil carbon storage. The study highlights the potential complex system to optimizing carbon storage in natural forest ecosystems, offering valuable insight for managing carbon sinks. Further research is needed to fully understand ecosystem responses to carbon storage across different forest habitats and different spatial-temporal scales.

Release of Organochlorine Pollutants from Forest Fires: 1. Emission Factors and Revisiting Their Emissions in the Himalayan Regions.

Worldwide forest fires have occurred frequently in recent years, a result of which may be the emission of so-called "legacy" organochlorine pollutants (OCPs) accumulated in forests. However, few studies have measured the emission factors (EFs) of the toxicity of the OCPs from forest fires. In this study, the EFs of vegetation burning were observed in forests along the altitudinal gradient from 1000 to 4200 m, and the EFs of ∑DDTs (dechlorodiphenylthrichloroethanes), HCB (hexachlorobenzene), ∑HCHs (hexachlorocyclohexanes), and ∑PCBs (polychlorinated biphenyls) were 2050 ± 1175, 379 ± 409, 48 ± 51, and 65 ± 59 ng/kg, respectively. Re-evaporation was the primary mechanism of the emission of OCP from forest fires. The masses of HCB, β-HCH, o,p'-DDD, p,p'-DDD, and PCB-28 in smoke increased 3-7 times compared with those in unburnt vegetation, suggesting the formation of these pollutants by the pyrolysis of biomass or other pollutants. Based on the observed EFs, previously estimated quantities of fire-emitted OCPs in the Himalayan regions were revisited. The DDT emissions from the Himalayan forest fires increased ∼70% compared with the previous estimation (from 19 to 32 kg/year). This highlighted that the EF observations could decrease the uncertainties of estimating OCP emissions from forest fires, which is helpful in revealing the potential roles of forest fires on global POP cycling.

Vapor Pressure Deficit Controls the Extent of Burned Area Over the Himalayas

AbstractGlobally, increasing occurrences of forest fires are major threats to the ecosystem. The rich forests in the Himalayas also suffer from high incidents of forest fires in the pre‐monsoon summer months, March to June. Research studies are limited in identifying the meteorological factors governing the spatiotemporal distribution of forest fires. Using three satellite‐based data sets of monthly burned area (BA) for March to June, we found higher BA in the Eastern Himalayas (EH) compared to the Central (CH) and Western Himalayas (WH). Using statistical methods, we found Vapor Pressure Deficit (VPD) to be the most dominating variable controlling BA in the Himalayas. Precipitation, soil moisture and temperature, with their relative variability, control VPD that governs the interannual and intraseasonal variations of BA. Our results imply that a good forecast of VPD will facilitate alert generation for the Himalayan forest fires.

Stand structure and disturbance history of old-growth blue pine (Pinus wallichiana) forests in the Bhutan Himalaya

Blue pine (Pinus wallichiana) forests are of significant ecological, economic, and cultural importance in the Himalayas. We used dendrochronological methods to investigate the role of natural and human disturbance in shaping the development of these forests. Analyses of the age structure and growth patterns of blue pine populations over the period 1760–2020 at two different sites in central Bhutan revealed that blue pine tends to establish as single-cohort stands following relatively intense disturbances and as multi-cohort stands after low-to-moderate severity disturbances. Shifting cultivation, which was common across the region, likely led to the establishment of single-cohort stands, particularly near human settlements, whereas natural disturbances are likely responsible for the development of multi-cohort stands. Tree-ring records revealed an acute change in recruitment patterns in the early 1970s associated with the 1969 Forest Act of Bhutan, which limited traditional practices, such as firewood collection and grazing, within the forests. This led to a sudden and sustained increase in the recruitment of broadleaf tree species and effectively curtailed blue pine regeneration over the past half century due to thick understory and midstory vegetation reducing the amount of light reaching the forest floor. These results highlight the role of disturbances, both human and natural, in driving forest stand dynamics in Himalayan forests and how forest policy and traditional practices can alter those dynamics.

Investigations on adsorptive removal of PVC microplastics from aqueous solutions using Pinus roxburghii-derived biochar.

This study investigates the adsorption mechanisms of pine bark biochar (BC) and modified pine bark biochar (MBC) in the removal of polyvinyl chloride (PVC) microplastics from aqueous solutions, with a significant focus on resource recovery from pine residues which is one of the key Himalayan Forest byproducts. The research findings highlighted the optimal adsorption capacity of biochar at 131.5mg/g achieved after 6h of contact time, with a pH of 10 and a PVC microplastic concentration of 200mg/L. The primary mechanisms of PVC microplastic adsorption involved ion exchange and physical adsorption, driven by forces such as Vander-Waals, London forces, and electrostatic forces. Thermodynamic analysis showed the exothermic nature of the PVC and BC/MBC interaction, with spontaneous adsorption occurring within the temperature range of 10 to 40°C. Isotherm and kinetic models fit well with Temkin model and PSO kinetics, as indicated by R2 values exceeding 0.9. Particularly, MBC exhibited superior removal efficiency and adsorption capacity compared to its precursor, reaching an optimum adsorption capacity of 156.08mg/g with a removal efficiency of 78%, surpassing the performance of BC. This research contributes valuable insights into potential applications of BC for PVC removal and underscores the effectiveness of MBC in achieving enhanced adsorption outcomes.

Climate change ecological vulnerability and hotspot analysis of himalayan forests in North-Eastern region, India

The Himalayan forests are vulnerable to climate change leading to disturb the current flow of critical ecosystem services to the dependent population. Present study attempts to evaluate the current vulnerability status of major forest types in Nagaland, India due to climate change along with identifying the hot spots for mitigating the vulnerability of the forests. Vulnerability of mixed moist deciduous, pine, wet hill and wet temperate forests were evaluated using the IPCC framework. Local Moran's I analysis, hot spot analysis and a histogram analysis of the vulnerability were made in QGIS. Field data such as Shannon-Wiener Index and Importance Value Index along with secondary data such as edaphic factors, vegetation factors and climatic variables were used for vulnerability analysis. Analysis results that mixed moist deciduous forests had the highest area in under high-high clusters, hot spots and was highly vulnerable. The result suggests that very dense or moderately dense forest cover were less vulnerable than low density forests in the region. The study provides baseline information along with identification of vulnerable hot spot forests for future climate change policy and management of resources at the division level. The study suggests strengthening the less dense forests along with increasing the biodiversity through suitable strategy for mitigating the vulnerability.

Balancing greenwashing risks and forest carbon sequestration benefits: A simulation model linking formal and voluntary carbon markets

Voluntary carbon markets (VCMs) offer energy-intensive firms a cost-effective means to reduce carbon mitigation expenses through promoting forest conservation. However, concerns about greenwashing may deter firms from using these options, which are susceptible to illegal forest harvesting. This study examines whether firms purchasing carbon credits from forestry-based communities can help strengthen forest conservation, mitigate project risks, improve environmental outcomes, and reduce abatement costs. We examine a large Indian steel firm, with an annual production capacity of 4 million tons, issuing green bonds to fund afforestation in Himalayan forest communities. Using industry-level average emissions, abatement costs, and output data for Indian firms, we develop a dynamic optimization model to determine optimal abatement strategies, considering the risk of future forest carbon loss from VCMs. The model, utilizing examples and data from existing carbon sequestration programs in the Himalayan states, offers insights into promoting high-integrity VCMs through formal emission market linkage. Findings suggest that firms' involvement in compliance emissions markets provides an alternative route to accessing affordable carbon credits when abatement costs are high. Additionally, engaging in the VCM reduces expenses related to emission reduction targets. However, with elevated greenwashing risks, firms reduce their use of green bonds in VCMs. Participation in the VCM positively reinforces forest conservation and enhances environmental services when greenwashing risks are absent, further lowering carbon mitigation costs. To enhance VCM integrity, further research is needed on how community conservation norms influence illegal harvesting.

Abundance, diversity and composition of understory plants along the altitudinal gradient and dominant overstory composition types in the temperate Himalayan region

IntroductionThe Indian Himalayan forests are remarkable landforms experiencing tremendous climatic variation, constituting complex and diversified ecosystems with prominent vegetation zones. Despite their global significance and substantial research efforts focused on plant diversity in the temperate Himalayan region, only a few studies have explicitly assessed the distribution patterns of understory vegetation in relation to forest compositional types along altitudinal gradients.MethodsTo cover a wide range of altitudes and diverse overstory compositions, stands were sampled across four altitudinal ranges from 1500 to 3500 meters above mean sea level with increments of 500 meters in elevation steps. The overstory compositions were classified on the basis of dominant tree species in each stand on the similar sites. Vegetation in the shrub and ground layers was surveyed by visually estimating the percentage coverage within circular plots.ResultsA total of 99 understory species including 37 species each in the shrub layer, 62 species in the herb layer vegetation were recorded. The abundance, species diversity and composition of understory vegetation differed significantly along the altitudinal gradient and dominant overstory composition types. Moreover, distinct understory vegetation communities were observed at lower elevations compared to higher elevations, with middle elevations exhibiting intermediate vegetation characteristics. The study also highlighted the importance of dominant overstory composition types in shaping the pattern of understory vegetation abundance, species diversity and composition in the temperate Himalayan region. The higher resource conditions associated with broadleaved stands supported higher understory species abundance at lower elevations, while the heterogeneous conditions induced by the mixedwood stands promoted higher understory species diversity.ConclusionThe hump shaped pattern along the altitudinal gradient appeared to be the most dominant pattern of plant abundance and species diversity and call for more conservation concern towards the middle elevation zones in the temperate Himalayan region. Furthermore, the management interventions should aim at maintaining diverse range of overstory composition types for conserving biodiversity and their ecological functions in the temperate Himalayan region.

Assessing forest villagers’ livelihood vulnerability to the environmental changes in Buxa Tiger Reserve of sub-Himalayan India

The Himalayan forest communities historically lived in harmony with their environment; however, anthropogenic activities have disrupted this balance. Deforestation, climate change, and habitat degradation have heightened vulnerability, compounded by human-wildlife conflicts (HWCs) and limited access to crucial livelihood capitals. Addressing these challenges requires a deeper understanding of factors associated with household-level vulnerability, prompting this study in the Buxa Tiger Reserve of sub-Himalayan India. Data from 345 households across ten villages reveal significant exposure to HWCs, particularly elephant crop raiding and leopard-induced livestock losses. Sensitivity arises from water scarcity, health issues, food shortages, and inadequate housing conditions, while limited adaptive capacity stems from infrastructural and financial constraints, among others. Spatial disparities emerge, with tribal households exhibiting lower exposure but lesser adaptive capacity compared to non-tribal communities. Proximity to different facilities (e.g., markets, financial institutions, primary healthcare centers) and government schemes significantly influence vulnerability, revealing unexpected associations. Besides, villagers’ willingness to relocate demonstrates higher adaptive capacity and perceived benefits outside the reserve. By unraveling the layers of vulnerability at the household level, this study provides valuable guidance for policymakers, forest managers, and other stakeholders. It offers insights into sustainable development strategies, resonating globally to harmonize human actions with environmental conservation.

Biomass and Carbon Stock Estimation through Remote Sensing and Field Methods of Subtropical Himalayan Forest under Threat Due to Developmental Activities

Biomass and Carbon Stock Estimation through Remote Sensing and Field Methods of Subtropical Himalayan Forest under Threat Due to Developmental Activities

Identification of Major Threats of Climate Change, Hazards, and Anthropogenic Activities on Biodiversity Conservation in the Buxa Tiger Reserve, India.

The Himalayan forests are facing a range of threats, which are making conservation efforts challenging. Using a mixed-method approach, this study investigated the threats to biodiversity conservation in Buxa Tiger Reserve (BTR), a fragile ecosystem in the Eastern Himalayan foothills. The study found that between 1990 and 2021, BTR experienced rising summer temperatures and decreasing annual precipitation, contributing to forest dryness, water scarcity, and forest fires. Natural disasters such as floods, flash floods, earthquakes, and landslides also caused significant damage to wildlife habitats. Changes in land use and land cover, including encroachment, infrastructure development, fuelwood collection, and grazing practices, were also identified as significant drivers of ecosystem alteration. Besides, hunting and poaching also emerged as threats to wildlife populations in the reserve. By employing the Analytic Hierarchy Process (AHP), the study determined that land use change, infrastructure development, climate change, livestock grazing, and fuelwood collection pose significant threats to flora conservation outcomes in BTR, while infrastructure development, climate change, livestock grazing, and forest fires are the primary threats to wildlife conservation outcomes in the reserve. The study recommends the regulation of land use practices, promotion of sustainable livelihoods for local communities, effective conservation strategies, and public awareness and education programs to promote the value of biodiversity conservation.

The Genus <I>Lactarius</I> in India

The genus Lactarius (family Russulaceae) is presently known by 56 species and 12 varieties from India. Based on a thorough survey of Himalayan forests and the reports by earlier workers, a detailed distribution, associated trees and the colour of the latex both before and after the exposure is presented for all the Indian taxa.

Classifying Pinus roxburghii Using an Innovative Training Approach of Fuzzy Models While Handling Heterogeneity Within Class in Western Himalayan Forests

Classifying Pinus roxburghii Using an Innovative Training Approach of Fuzzy Models While Handling Heterogeneity Within Class in Western Himalayan Forests

Seasonal and long-term changes in litterfall production and litter decomposition in the dominant forest communities of Western Himalaya

Understanding changes in litter fall is paramount for effective management, as it directly impacts ecosystem health, nutrient cycling, and overall biodiversity. It informs strategies for conservation, land use planning, and mitigating ecological disruptions. Therefore, present study investigates the seasonal and long-term changes in litterfall dynamics within the dominant forest communities of Western Himalaya. A total four distinct forest ecosystems, including Sal, (Shorea. robusta) Chir-pine (Pinus roxburghii), Banj-oak (Quercus leucotrichophora), and Mixed-oak (Q. leucotrichophora, Q. floribunda and Q. lanuginosa) forests were selected for the study. The total annual litter production across the forest stands varied from 741.59 to 841.22 g−2, with the highest recorded in the Banj-oak stand (841.22 g−2) and the lowest in the Sal stand (741.59 g−2). Leaf fall reported for the highest proportion of total litterfall (64.88% to 71%) across the forest stands, and peak litterfall was observed during the summer months in all forest sites. The leaf litter decomposition rate of selected species shows significant variation (F5, 10 = 3.41, p < 0.05) between species. Interestingly, litterfall production increased in all forest sites from 1980 to 82 to 2017–19. However, no significant changes were observed in the decomposition rate. The findings reveal significant variations in litterfall dynamics across different forest ecosystems, with leaf fall contributing substantially to total litter production. The observed increase in litterfall production over the studied period highlights the need for continued monitoring and adaptive management strategies to address potential ecological implications. These insights are invaluable for informing conservation efforts, land use planning, and mitigation strategies aimed at preserving ecosystem health, sustaining biodiversity, and ensuring the long-term resilience of Western Himalayan forests in the face of environmental change.

Two new species of Mallocybe from Himalayan forests of Asia

The genus Mallocybe is poorly studied in Asia, with little known species diversity of the genus in Himalayan forests of Pakistan, a hotspot for biodiversity. Based on morphological characters and molecular data, two new species of Mallocybe from Himalayas of Asia are described. One species, Mallocybe himalayana has been collected from Himalayas of China and Azad Jammu &amp; Kashmir, Pakistan. Mallocybe kashmiriana has been described from Himalayas of Azad Jammu and Kashmir, Pakistan. Detailed morphological descriptions, drawings of microstructures for novel taxa are provided. Phylogenetic analyses inferred from internal transcribed spacer (ITS), large subunit (LSU) and second largest subunit of RNA polymerase II (rpb2) sequences show the novelty of these taxa.

Accelerated anti-oxidant enzymes and phytochemical potential of Taxus wallichiana (Himalayan yew) under moist temperate forest of Himalayan, Pakistan

Abstract Taxus wallichiana (Himalayan yew) antioxidant potential enhances the release of secondary metabolites and enzymes under stress; over the last few decades owing to changes in climatic regimes, such species are under constant threat in the moist temperate Himalayan forests. The present study aims to evaluate the effect of change in land-use pattern on the antioxidant and phytochemical potential of T. wallichiana (Himalayan yew) in the moist temperate Himalayan Forest of Galiyat-Khyber-Pakhtunkhwa-Pakistan. Three leaf samples from each location of T.W were collected from high (Ayubiya, 2,970 m.a.s.l.) undisturbed, disturbed mid (Baragali, Dongagali, Kuldana, Chegagali, 2,617, 2,375, 2,455, 2,804 m.a.s.l.) and low (Murree, 2,000 m.a.s.l.) altitudes of moist temperate forest of Galiayt-Himalayan-Khyber-Pakhtunkhwa-Pakistan, DPPH assay, total flavonoids and phenolic content, total protein and proline content, catalase, superoxide dismutase and peroxidase activities were analysed. The antioxidant activity (DPPH) response was more pronounced in low and mid altitude disturbed sites than the undisturbed site at high altitudes. Antioxidant enzymes and osmolyte content further supported the stress tolerance capacity of T. wallichiana to scavenge the ROS produced under oxidative stress conditions. In conclusion, Taxus wallichiana inhabiting in these sites could withstand long durations of drought, salinity, frost, high temperatures, and pathogenic attacks by activating the antioxidant enzymes.

New species and new records of genus Buellia (lichenized Ascomycota, Caliciaceae) from Pakistan using electron microscopy and DNA barcoding techniques.

Three new species Buellia darelensis, B. densitheca, B. kashmirensis and two new records B. elegans and B. taishanensis are added to the lichen biota of Pakistan. Buellia darelensis and B. kashmirensis share the same habitats found on the rock while B. densitheca colonized on bark of Pinus hardwoods in the Himalayan forest, Pakistan. Morphological, chemical, and phylogenetic analyses were carried out to elucidate the placement of these species and to support the delimitation of the new taxa. Detailed descriptions and figures for the species are given, and a key to all known buellioid species from Pakistan is provided. RESEARCH HIGHLIGHTS: During recent explorations of lichens from different regions of Pakistan, we observed specimens that could not be readily assigned to any known species. A phylogenetic analysis of the internal transcribed spacer nrDNA region confirms their position within the genus Buellia, and morphological data showed distinctiveness of three species from other known species of the genus. We therefore describe these specimens as new species to science, and two species are as new records for the country. Pakistan exhibits a large altitudinal variation, with climatic conditions and a diverse vegetation that supports a diverse and conspicuous lichen biota. The nature reserves have abundant biological resources, and it is expected that more new species of lichen may be discovered in the future.