Bioclimatic Zones Research Articles

Improving Sri Lankan Buildings' Energy Efficiency Through Bioclimatic Classification and Potential Assessment

As a result of lifestyle changes, the energy requirement for thermal comfort has increased. To increase energy efficiency and reduce global warming, building design should consider the climate. An energy-efficient building code has been developed with the goal of reducing energy demand by 25%–40%. However, the code cannot be used because different stakeholders have different perspectives. Climate zones, which are required for building structures that are both energy-efficient and climate-responsive, do not exist in the country. From 1989 to 2019, hourly weather data has been collected for district headquarters. This research focuses on the bioclimatic classification of Sri Lankan buildings and passive design methods. Degree days have been calculated for various base temperatures using Hitchin's, Erb's, Schoenau and Kehring's, ASHRAE, UKMO, and Hourly methods. The degree-day maps for Sri Lanka were created using ArcGIS. The bioclimatic classification for Sri Lanka was developed by combining climate and degree-day data. Sri Lanka is divided into three bioclimatic zones: cold, hot, and intermediate. The design potential of each bioclimatic zone was calculated using BcChart V2.0. Natural ventilation is an effective passive design technique for increasing indoor comfort. In the cold, hot, and intermediate zones, its potential is 72%, 62%, and 80%, respectively.

Effects of teleconnection indices on net primary production (NPP) in bioclimatic zones of Iran

Effects of teleconnection indices on net primary production (NPP) in bioclimatic zones of Iran

Biochar influence on the development of spring wheat (Triticum aestivum L.) and acidity of soddy-podzolic soil in Western Siberia

The paper purpose was to establish the effect of applying biochar obtained from various organic wastes of agriculture (cow manure, straw), woodworking (pine sawdust) and food industry (pine nut shell), which are typical of Western Siberia, on the morphometric characteristics of plants (using spring wheat (Triticum aestivum L.) as the example) and the soddy-podzolic soil properties. The assessment of biochar influence was performed by a series of vegetation experiments using climatic chambers. As a result, it was found that the introduction of all the noted biochar types into the soil layer leads to a significant (p < 0.05) increase in the morphometric characteristics of spring wheat. For example, when applying the straw biochar to the soil, it results in growing the plant height to the node by 19%, while the number of leaves increased by 8% compared to the control variant. The introduction of biochar from manure leads to the increased length of the spring wheat root by 35%. Moreover, straw and manure biochars contribute to the reduction of soil acidity (increase in pH values from 7.1 to 7.4 and 7.8, respectively). The results of the comprehensive analysis indicate that the agronomic advantages of application of biochars obtained from wheat straw and cattle manure are better compared to biochars from pine sawdust and pine nut shells, which is due to higher concentration of nutrients and substances with alkaline reaction (carbonates and oxides) in the former. The results obtained are useful from the point of view of assessing the environmental risks when applying biochar ameliorants in soils typical of the boreal bioclimatic zone. Subsequent experiments, including studies of the joint application of biochars and fertilizers to the soil, will make it possible to develop recommendations for applying the thermal conversion technology for recycling the regional organic waste into ameliorants that improve soil quality and increase its fertility.

Response of the dung beetle community to different climatic zones: Does the land use system matter?

AbstractThe conversion of Brazilian savanna into exotic pastures leads to the loss of dung beetles and a decrease in their contribution to ecological functions. We hypothesized that the dung beetle communities from exotic pastures would show greater significant differences between climatic zones, when contrasted to communities from Brazilian savanna in the same region, since dung beetle assemblages in pastures are more simplified. We assessed which variables (purpose of production, type of management, percentage the habitat per buffer, soil penetration resistance, pasture area and herd size) affect more the dung beetle community in exotic pastures. We carried out this study in 48 areas of native Brazilian savannas and exotic pastures distributed across four bioclimatic zones: BZ1, hot with three dry months; BZ2, hot with 4–5 dry months; BZ3, sub‐hot with 4–5 dry months and BZ4, meso‐thermal with 4–5 dry months of Minas Gerais State, Brazil. In each BZ, six areas of Brazilian savannas and six areas of exotic pasture were selected. In the Brazilian savanna areas, the species richness, abundance and biomass of dung beetles did not differ between the bioclimatic zones, unlike the exotic pastures. The composition of the dung beetle community was different between land use systems and between bioclimatic zones; the interaction between the two factors was also significant. Our results provide evidence that dung beetle communities active in exotic pastures are more susceptible to climatic environmental variations than communities from more complex and stable habitats, such as savannas. Finally, the best model suggested that all the six variables combined explained about 91% of the total variability in species composition observed between sampling sites.

Analysis of the Fire Season of 2020 in the Mediterranean Bioclimatic Zone of Croatian Adriatic

Fire season in the Mediterranean bioclimatic area is most associated with the period from June to late October. Despite this, a large number of fires occur in February and March due to the intentional burning of agricultural lands. A characteristic of the Mediterranean region is the strong adaptation of vegetation to fire, though this adaptation also depends on the frequency and intensity of fires. This frequency is shown on satellite images via MODIS. This paper provides an overview of indicators of vegetation fires in the Croatian coast and karst coastal belt in the 2020 fire season. The 2020 fire season was above average in comparison with the period 2010 to 2019, with more fires than average and more burnt area. A specificity of the 2020 season is seen in the large number of fires in February and March. Fire protection in Croatia is facilitated by the use of new remote sensing technologies, in combination with the existing surveillance and monitoring methods, and organised protection systems to prevent open fires.

Biochemical Composition and Biological Activities of Various Population of Brassica tournefortii Growing Wild in Tunisia

Brassica tournefortii Gouan, commonly known (Aslooz) in Tunisia, is an annual plant, native to the North Africa and Middle East. Brassica species are used as food, their young leaves can be cooked, providing nutrients and health-giving phytochemicals such as phenolic compounds, polyphenols and carotenoids. Phytochemical composition and bioactivity of Brassica tournefortii leaf extracts, collected from four different bioclimatic zones in Tunisia, are investigated in the present study. Results showed that location and climatic variations can alter the phytochemical composition of B. tournefortii. Interestingly, HPLC analysis enabled identifying lutein and beta-carotene at high concentrations, especially in extracts of B. tournefortii collected from Gabes (B2) (344 µg/g of lutein) and B. tournefortii collected from Zarzis (B3) (1364 µg/g of beta-carotene). In particular, the antioxidant activity measured by DPPH assay showed that the extract of the plants collected from the growing region of Zarzis exhibits the highest antioxidant activities (0.99 mg/mL). All the Brassica tournefortii extracts showed a relevant antiproliferative activity, especially toward the Caco-2 cell line. These preliminary data resulted in being useful to correlate growth environmental conditions with different accumulation of metabolites in Brassica species still being poorly studied.

Altitude-specific differences in tree-ring δ2H records of wood lignin methoxy in the Qinling mountains, central China

The Qinling Mountains (Qinling Mts.) are characterized as a distinct transition of bioclimatic zones along the north-south geographic boundary in China. Although ongoing global warming may affect the growth of most tree species across elevation gradients, the effect of modern warming on the stable hydrogen isotopes of tree-ring wood is still unknown. In this study, we developed early- and late-wood δ2H chronologies from 1900 to 2018 CE of lignin methoxy groups (δ2HLM) at 700-m intervals from 1700 to 3100 m a.s.l. along the elevation gradient in Mount Taibai (Mt. Taibai), the peak of the Qinling Mts. The δ2HLM values of the earlywood were relatively enriched in 2H compared to the latewood, and an elevation-dependent depleting trend along the altitudinal gradient was observed. Comparing the δ2HLM values with modelled δ2H values of precipitation (δ2HPre) of the sample sites, similar isotopic patterns can be obtained. The reconstructions of δ2HPre values confirm the strong coherence between the isotopic composition of the source water and the methoxy groups in the growing season. The consistency of δ2HLM chronologies between the early- and late-wood at the higher sites was stronger than that at the lower sites. The additional lagged effect and climate response revealed significant seasonal and altitudinal differences. At the timberline site, δ2HLM values of earlywood were mainly related to the January and February temperatures, whereas δ2HLM values of latewood correlated most strongly with temperature from July to September, and both values were controlled by the amount of total precipitation. In addition, the combined new δ2HLM chronologies, based on the lag-1 autocorrelation and the weighted average of the current year earlywood and previous latewood, could be used to merge the corresponding temperature signals from the middle- and low-elevation sites. Altitudinal correlations of elevation offset between the annual δ2HLM chronologies and interpolations of precipitation and temperature suggested that the δ2HLM values at higher elevations better represent regional climatic changes. Therefore, topographic effects such as elevation differences should be considered in large-scale applications of δ2HLM values in future studies.

Comparison of the Two Most Common Phenology Algorithms Imbedded in Land Surface Models

AbstractA reasonable representation of plant phenology in land surface models (LSMs) is necessary to accurately simulate the momentum, heat, and mass interchanges between land and the atmosphere from ecosystem to global scales. Many process‐based phenology algorithms have been developed and coupled to LSMs to describe seasonal vegetation changes. The growing degree day (GDD) and the growing season index (GSI) algorithms are the two most well‐known algorithms used in LSMs for simulating phenophases. However, assessments of these two most commonly used phenology algorithms in LSMs are quite scarce. In this study, these two phenology algorithms were respectively coupled with the Community Land Model (CLM) and the Dynamic Land Model (DLM) to obtain four modeling scenarios. The simulation accuracy of phenophases and gross primary production (GPP) in the four scenarios was assessed against observations at the site scale, focusing on deciduous forests and grasses. The three main findings were as follows: (a) the difference in simulated phenological events between different LSMs coupled with the same phenological algorithm was small and less than 1 day, DLM performed better than CLM; (b) compared with the GSI algorithm and regardless of whether it was coupled with the DLM or CLM model, the GDD model performance was better for spring phenology and worse for autumn phenology; (c) GSI performance was better than GDD for GPP simulation over different vegetation function types across different bioclimatic zones: on average, the root mean square error and the index of agreement were about 8.0% higher and about 6.5% lower, respectively.

Chemical analysis of Iranian Rosa damascena essential oil, concrete, and absolute oil under different bio-climatic conditions

Rosa damascena Mill., the unique species of Rosaceae , is one of the valuable medicinal and ornamental aromatic plants cultivated in different parts of Iran. Climatic conditions impact the productivity and yield of rose products. This work was designed to study the chemical composition of the essential oil, concrete, and absolute oil of Rosa damascena Mill. (same genotype) collected from three different bio-climatic areas belonging to semi-arid, cold (Qamsar and Niyasar in Isfahan province), semi-arid, very warm and dusty (Maymand in Fars province), and arid, cold and windy (Lalezar in Kerman province) regions (as important rose growing centers) of Iran for the first time. All R. damascena samples were investigated using GC-FID, and GC-MS methods, to evaluate phytochemical constitutions. The sample yields were in the range of 0.03–0.04 % for essential oil, 0.29–0.40 % for concrete, and 0.07–0.19 % for absolute. The citronellol/geraniol ratio (C/G), the main quality determining factor of essential oil, was found to vary from 3.3 % to 6.9 % in essential oil. It was observed that R. damascena growing at semi-arid, cold such as Qamsar had a higher C/G factor, while those growing at the same bio-climatic zone with low altitude, Niyasar, had a lower C/G ratio. Phenyl ethyl alcohol prevailed in Co with 44.5 %, 47.2 %, 45.2 %, and 45.1 % for Qamsar, Niyasar, Meymand, and Lalezar, respectively. On the other hand, GC-MS analysis of absolute oil showed that phenyl ethyl alcohol, citronellol , and phenolic terpenoids are three major components that take more than 60 % of total rose absolute in four areas. Essential oil, concrete, and absolute oil of the Qamsar region were considered to have a high quality in terms of richness in C/G ratio and phenyl ethyl alcohol monoterpenes. The concrete and absolute composition of the residual waste petals (prepared from one of the rose water companies in Qamsar) were also studied, and the results showed that the amount of concrete in the waste petals was relatively significant and could be considered as an important by-product. According to findings, it can be concluded that quantitative and qualitative properties of R. damascena productions are affected by bio-climatic conditions and environmental factors that are useful for optimum production. Some factors and alternative methods affecting in C/G ratio and phenyl ethyl alcohol increasing recommended. • Composition of the essential oil, concrete, and absolute of Iranian R. damascena from different areas was investigated. • The citronellol/geraniol ratio, as the main quality determining factor of essential oil, was found to vary from 3.3 to 6.9 %. • The Qamsar region was considered to have a high quality in terms of richness in C/G ratio and phenyl ethyl alcohol. • Quantitative and qualitative properties of R. damascena productions are affected by bio-climatic conditions.

Slow and steady wins the race: Diversification rate is independent from body size and lifestyle in Malagasy skinks (Squamata: Scincidae: Scincinae)

Most of the unique and diverse vertebrate fauna that inhabits Madagascar derives from in situ diversification from colonisers that reached this continental island through overseas dispersal. The endemic Malagasy Scincinae lizards are amongst the most species-rich squamate groups on the island. They colonised all bioclimatic zones and display many ecomorphological adaptations to a fossorial (burrowing) lifestyle. Here we propose a new phylogenetic hypothesis for their diversification based on the largest taxon sampling so far compiled for this group. We estimated divergence times and investigated several aspects of their diversification (diversification rate, body size and fossorial lifestyle evolution, and biogeography). We found that diversification rate was constant throughout most of the evolutionary history of the group, but decreased over the last 6–4 million years and independently from body size and fossorial lifestyle evolution. Fossoriality has evolved from fully quadrupedal ancestors at least five times independently, which demonstrates that even complex morphological syndromes – in this case involving traits such as limb regression, body elongation, modification of cephalic scalation, depigmentation, and eyes and ear-opening regression – can evolve repeatedly and independently given enough time and eco-evolutionary advantages. Initial diversification of the group likely occurred in forests, and the divergence of sand-swimmer genera around 20 Ma appears linked to a period of aridification. Our results show that the large phenotypic variability of Malagasy Scincinae has not influenced diversification rate and that their rich species diversity results from a constant accumulation of lineages through time. By compiling large geographic and trait-related datasets together with the computation of a new time tree for the group, our study contributes important insights on the diversification of Malagasy vertebrates.

Physico-chemical properties of crude oil of Khaya senegalensis (Desr.) A. Juss according to bioclimatic zones in Chad

Physico-chemical properties of crude oil of Khaya senegalensis (Desr.) A. Juss according to bioclimatic zones in Chad

Dummy regression to predict dry fiber in Agave lechuguilla Torr. in two large-scale bioclimatic regions in Mexico.

Agave lechuguilla Torr., of the family Agavaceae, is distributed from southwestern United States to southern Mexico and is one of the most representative species of arid and semiarid regions. Its fiber is extracted for multiple purposes. The objective of this study was to generate a robust model to predict dry fiber yield (Dfw) rapidly, simply, and inexpensively. We used a power model in its linear form and bioclimatic areas as dummy variables. Training, generation (80%) and validation (20%) of the model was performed using machine learning with the package ‘caret’ of R. Using canonical correlation analysis (CCA), we evaluated the relationship of Dwf to bioclimatic variables. The principal components analysis (PCA) generated two bioclimatic zones, each with different A. lechuguilla productivities. We evaluated 499 individuals in four states of Mexico. The crown diameter (Cd) of this species adequately predicts its fiber dry weight (R2 = 0.6327; p < 0.05). The intercept (β0), slope [lnCd (β1)], zone [(β2)] and interaction [lnCd:Zona (β3)] of the dummy model was statistically significant (p < 0.05), giving origin to an equation for each bioclimatic zone. The CCA indicates a positive correlation between minimum temperature of the coldest month (Bio 6) and Dwf (r = 0.84 and p < 0.05). In conclusion, because of the decrease in Bio 6 of more than 0.5°C by 2050, the species could be vulnerable to climate change, and A. lechuguilla fiber production could be affected gradually in the coming years.

Spatial analysis of bioclimatic patterns over Iranian cities as an important step in sustainable development

• In this study determined the bioclimatic component loading patterns over Iran. • The results showed that the first Varimax-rotated loading pattern accounts for 51.82% of the total variances. • This study presented novel insights into the identification of bioclimatic regions in Iran. • Cluster analysis demonstrated that Iran can be divided into five bioclimatic regions based on PCA. • Spatial distribution of bioclimatic zones showing geographical dependency. The main objective of this paper is to classify bioclimatic regions in Iran for optimal environmental planning. Mean daily meteorological data of 155 well-distributed synoptic stations during 1995–2017 were extracted from Iran's Meteorological Organization. Percentage of occurrence of each thermal sensation classes was determined over all studied stations using five bioclimatic indices including Perceived Temperature (PT), Physiological Equivalent Temperature (PET), Predicted Mean Vote (PMV), Standard Effective Temperature (SET) and Universal Thermal Climate Index (UTCI). An R-mode Principal Component Analysis (PCA) was applied to a N × M (155 × 40) matrix of N = 155 stations and M = 40 total thermal thresholds based on all used indices during the considered time period. According to the results of PCA, the five loading PCs that approximately account for 98.5% of the total variance were selected for further analysis. In addition, Ward method was used for Cluster Analysis (CA) to divide the stations into different bioclimatic groups. The results illustrated that the first Varimax-rotated loading pattern which accounts for 51.82% of total variance characterized Northwest of Iran with more than 0.8 PC scores. Furthermore, cluster analysis demonstrated that Iran can be divided into five bioclimatic regions based on the R-mode PCA.

Comparison of Nutritive Values of Tropical Pasture Species Grown in Different Environments, and Implications for Livestock Methane Production: A Meta-Analysis.

Simple SummaryGlobally, tropical pasture species predominate in tropical and subtropical climates, and are the primary feed source for grazing livestock including dairy cattle. Therefore, this study aimed at systematically analysing the nutritive values of tropical pastures and the implications of potential methane gas production from tropical pasture species and livestock, in relation to the growing conditions and agronomic management approaches used (defoliation frequency and intensity) across different climates. This analysis allowed us to understand the better performing tropical pasture species grown across wider geographical regions, in order to improve pasture-based livestock production systems. Results revealed that pasture quality and methane gas production varied among and within species, and were significantly affected by the climate and by the agronomic management regime as well.The demand for dairy products is ever increasing across the world. The livestock sector is a significant source of greenhouse gas (GHG) emissions globally. The availability of high-quality pasture is a key requirement to increase the productivity of dairy cows as well as manage enteric methane emissions. Warm-season perennial grasses are the dominant forages in tropical and subtropical regions, and thus exploring their nutritive characteristics is imperative in the effort to improve dairy productivity. Therefore, we have collated a database containing a total of 4750 records, with 1277 measurements of nutritive values representing 56 tropical pasture species and hybrid cultivars grown in 26 different locations in 16 countries; this was done in order to compare the nutritive values and GHG production across different forage species, climatic zones, and defoliation management regimes. Average edaphoclimatic (with minimum and maximum values) conditions for tropical pasture species growing environments were characterized as 22.5 °C temperature (range 17.5–29.30 °C), 1253.9 mm rainfall (range 104.5–3390.0 mm), 582.6 m elevation (range 15–2393 m), and a soil pH of 5.6 (range 4.6–7.0). The data revealed spatial variability in nutritive metrics across bioclimatic zones and between and within species. The ranges of these nutrients were as follows: neutral detergent fibre (NDF) 50.9–79.8%, acid detergent fibre (ADF) 24.7–57.4%, crude protein (CP) 2.1–21.1%, dry matter (DM) digestibility 30.2–70.1%, metabolisable energy (ME)3.4–9.7 MJ kg−1 DM, with methane (CH4) production at 132.9–133.3 g animal−1 day−1. The arid/dry zone recorded the highest DM yield, with decreased CP and high fibre components and minerals. Furthermore, the data revealed that climate, defoliation frequency and intensity, in addition to their interactions, have a significant effect on tropical pasture nutritive values and CH4 production. Overall, hybrid and newer tropical cultivars performed well across different climates, with small variations in herbage quality. The current study revealed important factors that affect pasture nutritive values and CH4 emissions, with the potential for improving tropical forage through the selection and management of pasture species.

The variation of abundance and fruit damage of &lt;em&gt;Bactrocera dorsalis&lt;/em&gt; on two commercial varieties of Mangifera indica in main Bio-climatic Zones of Sri Lanka

Bactrocera dorsalis Hendel, (Diptera: Tephritidae) is one of the serious fruit pests in Sri Lanka. The present study aims to investigate the abundance of B. dorsalis adults and their infestation levels on Willard (Wld) and Karutha kolomban (Kc) mango varieties grown in main bio-climatic zones of Sri Lanka.The study was conducted from September 2020 to February 2021 in 08 study sites of 04 main bio-climatic zones. In every month, flies were collected from field traps. Infested fruits were also collected from study sites and fruit fly infestation levels and adult emergence were studied in the laboratory. The significance levels in the variations of percentage infestation, adult emergence and abundance of caught flies were compared among varieties, study sites, and with the climatic variables. Mean weight (g) of the tested mango fruits were (112.71 ± 1.78) g and (290.75 ± 4.23) g for Wld and Kc respectively. The intermediate zone recorded the highest percentage of average infestation (Wld, p&gt;0.05; Kc, p

Tree Maladaptation Under Mid-Latitude Early Spring Warming and Late Cold Spell: Implications for Assisted Migration.

Global warming is predicted to extend the growing season of trees and plants, and advance spring phenology. However, intensification of extreme climate events in mid-latitude forests, from weakening of the jet stream and atmospheric blockings, may expose trees to increased risk associated with more frequent late-spring frosts. Still, little is known regarding the intraspecific variation in frost tolerance and how it may be shaped by local adaptation to the climate of seed origin. As part of an assisted migration trial located in different bioclimatic zones in the province of Quebec, Canada, and following an extensive late-spring frost that occurred at the end of May 2021, we evaluated the frost damages on various white spruce (Picea glauca) seed sources tested on three sites (south, central, and north). The severity of frost damages was assessed on 5,376 trees after the cold spell and an early spring warming which advanced bud flush by approximately 10 days on average. The frost damage rate was similar among sites and seed sources and averaged 99.8%. Frost damage severity was unrelated to the latitude of seed origin but was variable among sites. The proportion of severely damaged trees was higher in the northern site, followed by central and southern sites. The proportion of severely damaged trees was linearly and inversely related to tree height before the frost event. Apical growth cancelation was not significantly different among seed sources including local ones, and averaged 74, 46, and 22%, respectively, in central, northern, and southern plantation sites. This study provides recommendations to limit the loss of plantation productivity associated with such a succession of spring climate anomalies. Implications for seed transfer models in the context of climate change and productivity of spruce plantations are discussed in the light of lack of local adaptation to such pronounced climate instability and ensuing large-scale maladaptation.

Determining the Biocomfort Zones in Near Future in Antalya Province Depending on the Global Climate Change Scenarios

Climate is a factor that affects the entire life of humans such as physiological development and characteristics, housing and house structures, food and cloth selections, and distribution on land. It is projected that global climate change would cause important changes in climate parameters in near future and affect the lives of all organisms on the earth directly or indirectly. It is estimated that these changes would cause significant changes in biocomfort zones. Thus, it is important to determine the biocomfort zones depending on the climate change scenarios and to use them in urban planning studies. In this study, it was aimed to determine the change in bioclimatic comfort zones in Antalya depending on the projected climate change scenarios. Within the scope of this study, considering the SSPs 245 and SSPs 585 scenarios of Coupled Model Intercomparison Project Phase 6, that is the 6th assessment report of IPCC, it was aimed to determine the current status and possible changes in biocomfort zones in Antalya in years 2040, 2060, 2080, and 2100. The results showed that the comfort zones in Antalya will generally shift from cold to hot towards the year 2100, that this shift will be at important level, and that the highest level of increase will be seen in southern regions with high population density and intense touristic activities.

Investigation of relationship between land use/cover (LULC) and GIS-based bioclimatic comfort zones based on environmental climate parameters and bioclimatic indices

Investigation of relationship between land use/cover (LULC) and GIS-based bioclimatic comfort zones based on environmental climate parameters and bioclimatic indices

Long‐term drivers and timing of accelerated vegetation changes in African biomes and their management implications

AbstractAimOwing to its diverse bioclimatic zones, long human history and intense anthropogenic impacts, Africa provides a model system for studying how global terrestrial ecosystems might respond to accelerated socio‐environmental stress. Africa is particularly vulnerable to climate change and human impact, and insufficient baseline data hamper current environmental management efforts. Using palaeoecological data, we seek to identify the timing, pace and drivers of change in African biomes on a long‐term scale to inform current ecosystem management frameworks on the continent.LocationAfrica.Time period0–12 ka.Major taxa studiedAfrican biomes.MethodsSixty‐four pollen records across Africa and nearby sites were retrieved from multiple databases/sources and grouped into biomes. Turnover (quantified using the squared chord distance dissimilarity metric) and rarefaction analyses were conducted on pollen records in each biome group to reconstruct regional temporal vegetation turnover and richness. Reconstructed vegetation turnover and richness were compared with independent records of climate, fire and human activity to identify possible drivers of change.ResultsWe found that the most stable biomes were those with the greatest floristic richness. Southern Africa's mediterranean‐type (SAM) ecosystems were the most stable and northern Africa's mediterranean‐type (NAM) ecosystems were the most unstable (mainly owing to fire). Tropical savannas (TS) and SAM ecosystems expressed the most sensitivity to climatic shifts from ≥6 ka, whereas tropical forests (TF) were relatively stable before human activities intensified from c. 2 ka. Floristic richness also declined across the tropics from c. 2 ka.Main conclusionsOur analysis pinpoints NAM ecosystems as undergoing the fastest acceleration in turnover on the continent in response to fire, whereas TF and TS have been undergoing unprecedented changes in biodiversity in the last 2,000 years. We expect further changes in biodiversity where climate becomes warmer and drier and where human impacts are novel and rapid in comparison to long‐term baselines.

Time-series maps reveal widespread change in plant functional type cover across Arctic and boreal Alaska and Yukon

Widespread changes in the distribution and abundance of plant functional types (PFTs) are occurring in Arctic and boreal ecosystems due to the intensification of disturbances, such as fire, and climate-driven vegetation dynamics, such as tundra shrub expansion. To understand how these changes affect boreal and tundra ecosystems, we need to first quantify change for multiple PFTs across recent years. While landscape patches are generally composed of a mixture of PFTs, most previous moderate resolution (30 m) remote sensing analyses have mapped vegetation distribution and change within land cover categories that are based on the dominant PFT; or else the continuous distribution of one or a few PFTs, but for a single point in time. Here we map a 35 year time-series (1985–2020) of top cover (TC) for seven PFTs across a 1.77 × 106 km2 study area in northern and central Alaska and northwestern Canada. We improve on previous methods of detecting vegetation change by modeling TC, a continuous measure of plant abundance. The PFTs collectively include all vascular plants within the study area as well as light macrolichens, a nonvascular class of high importance to caribou management. We identified net increases in deciduous shrubs (66 × 103 km2), evergreen shrubs (20 × 103 km2), broadleaf trees (17 × 103 km2), and conifer trees (16 × 103 km2), and net decreases in graminoids (−40 × 103 km2) and light macrolichens (−13 × 103 km2) over the full map area, with similar patterns across Arctic, oroarctic, and boreal bioclimatic zones. Model performance was assessed using spatially blocked, nested five-fold cross-validation with overall root mean square errors ranging from 8.3% to 19.0%. Most net change occurred as succession or plant expansion within areas undisturbed by recent fire, though PFT TC change also clearly resulted from fire disturbance. These maps have important applications for assessment of surface energy budgets, permafrost changes, nutrient cycling, and wildlife management and movement analysis.