Vegetation Dynamics Research Articles

Integrating real-time sensor data for improved hydrogeotechnical modelling in landslide early warning in Western Himalaya

This study presents a comprehensive investigation into developing a real-time monitoring framework for a localized landslide early warning system (LEWS), focusing on the hydrological dynamics of an unsaturated slope near the Joshimath Badrinath Highway in Uttarakhand, India. Considering the steepness of the slope and its adjacency to the highway, continuous monitoring and stability assessment are crucial. The framework encompasses primary phases of monitoring, modelling, forecasting, and warning. Monitoring collected hydrological and meteorological data, used for modelling and calibration. Validation using Taylor diagrams ensured accuracy by comparing predicted and monitored data. The calibrated hydrological model guided slope stability modelling to identify instability factors. A machine learning algorithm detected potential instability. Forecasting predicted unstable periods, triggering warnings if the factor of safety (Fs) values drop below 1.5. The study provided important insights into slope stability, highlighting the significance of vegetation parameters in accurately assessing slope stability using the Fs. Calibration of the hydrogeological model, particularly considering rainfall, climate, and vegetation data, improved the alignment between predicted and observed volumetric water content (VWC), especially in shallower depths. However, modelling hydrological dynamics at greater depths remains challenging, emphasizing the need for refined approaches. Machine learning techniques, specifically a Random Forest model, achieve high accuracy in predicting Fs, identifying VWC at 0.3-m and 3-m depths as pivotal variables. Temporal evaluation suggests a 12-month simulation as optimal, showing consistent performance across depths. Overall, the study advances slope stability modelling and offers insights into sustainable slope management practices, highlighting the complex interplay between climate, vegetation, and hydrological dynamics in unsaturated slopes. This approach lays a foundation for effective LEWS in Indian Himalayan states.

Post-fire vegetation dynamics and location as main drivers of fire recurrence in Mediterranean forests

Fire recurrence is a common phenomenon in Mediterranean forests that interrupts secondary ecosystem successions, hinders regeneration processes, and delays forests from reaching mature stages. To understand the occurrence of successive fires, we investigate the linkages between post-fire vegetation development and subsequent fire events in Eastern Spain during the period 1993–2015. In our study, we analyze annual burnt areas and derive a forest fire recurrence index that we use to explain the factors driving the occurrence of successive fires in previously burnt areas.Based on our results, fire recurrence is largely influenced by post-fire vegetation, as well as by topography and accessibility. Forests dominated by shrubs and sclerophyllous vegetation present higher probabilities of reburnt areas than tree forests. Fire recurrence is time-dependent, with the year of the first fire being an important factor in explaining the proportion of areas burnt twice. Identifying the characteristics and post-fire vegetation types in locations with higher recurrence probabilities can help to pinpoint priority areas and time windows for applying fire prevention and mitigation actions in already vulnerable forests.

Late Pleistocene to Holocene vegetation changes in southeastern Patagonia (49° S): landscape changes related to disturbances

ABSTRACTSoutheastern Patagonia's (49° S) post‐glacial history inferred from high Andean lake sediments provides new insights regarding Late Pleistocene and Holocene vegetation dynamics at the eastern margin of the Southern Patagonian Icefield. The fossil records of pollen, charcoal and geochemical data from tephra layers from Laguna Chiquita and Laguna Gemelas Este were analysed to reveal past landscape dynamics related to vegetation changes, fire and volcanic events from ca. 15 200 cal a bp to the present. Nothofagus forest expanded over shrubland communities sometime between 15 200 and 4600 cal a bp, along with at least three disturbance sources related to the volcanic eruptions of Lautaro, Aguilera and Hudson, important local fire episodes, and neoglacial advances. Major charcoal deposition reveals moderate fire activity during the Late Pleistocene related to an open landscape characterised by a grass/shrub steppe. Local glacier advances may have affected the Laguna Gemelas Este sedimentation. Tephra deposition events do not correlate to vegetation changes inferred from the Laguna Gemelas Este and Laguna Chiquita pollen records. Late Holocene eastern Andean forest changes and fire activity at 49° S match other southern palaeoenvironmental records (50–52° S) suggesting that changes in the Southern Westerly Wind latitudinal position and intensity drove major palaeovegetation and fire dynamics before the European settlement. In the last centuries, fire and vegetation changes have been closely related to an increase in local ignition sources and the introduction of alien species.

Wavelet-based analysis of hydro-climatic and vegetation dynamics in heterogeneous agro-climatic zones of East Africa

ABSTRACT Natural and human-induced factors profoundly affect agricultural crop production in East Africa, sparking ongoing debates about their relative significance. This study investigates the impact of localized hydro-climatic variables like precipitation, temperature, vapor pressure deficit, and water deficit on crop production. Additionally, it examines climate oscillations such as El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). Employing the Normalized Difference Vegetation Index (NDVI) metric, analysis focuses on four climatic zones, ranging from arid to humid. Results suggest that the dominant periodicities for NDVI and hydro-climatic factors are annual (8-16 months) and intra-annual (4-8 months), while circulation indices exhibit inter-annual and inter-decadal periodicity. The study reveals that vegetation dynamics are more sensitive to annual and intra-annual fluctuations in hydro-climatic factors compared to inter-annual and inter-decadal oscillations in circulation indices. The bi-variate wavelet coherence (WTC) analysis reveals that precipitation and ENSO are the most significant factors explaining vegetation variability, while multiple wavelet coherence (MWC) analysis demonstrates that all variables contribute significantly to NDVI variability. This research underscores the importance of wavelet techniques in deciphering complex relationships between hydro-climatic factors and crop production, with implications for agricultural management and policy in East Africa.

Vegetation dynamics following three decades of trophic rewilding in the mesic grasslands of Oostvaardersplassen

Vegetation dynamics following three decades of trophic rewilding in the mesic grasslands of Oostvaardersplassen

Carbon isotope trends across a century of herbarium specimens suggest CO2 fertilization of C4 grasses.

Increasing atmospheric CO2 is changing the dynamics of tropical savanna vegetation. C3 trees and grasses are known to experience CO2 fertilization, whereas responses to CO2 by C4 grasses are more ambiguous. Here, we sample stable carbon isotope trends in herbarium collections of South African C4 and C3 grasses to reconstruct 13C discrimination. We found that C3 grasses showed no trends in 13C discrimination over the past century but that C4 grasses increased their 13C discrimination through time, especially since 1950. These changes were most strongly linked to changes in atmospheric CO2 rather than to trends in rainfall climatology or temperature. Combined with previously published evidence that grass biomass has increased in C4-dominated savannas, these trends suggest that increasing water-use efficiency due to CO2 fertilization may be changing C4 plant-water relations. CO2 fertilization of C4 grasses may thus be a neglected pathway for anthropogenic global change in tropical savanna ecosystems.

Vegetation and Soil Dynamics : Insights from Prosopis juliflora- Intruded Areas in Hastinapur Wildlife Sanctuary

Ecological study on plant diversity and soil characteristics of two contrasting sites (Prosopis juliflora-invaded and non-invaded) in Hastinapur Wildlife Sanctuary was undertaken to understand the structure of vegetation and soils and implication of exotic dominance in a dry tropical region of India. Seasonal floristic composition was recorded for one year through monthly visits. Phytosociological study of the two sites in each of three seasons was carried out by sampling a total of 120 quadrats (each 1mx1m, n= 20×3×2). Plant species density and abundance was estimated for both sites in each season. Seasonal surface soil (0–10 cm) samples were analyzed for soil pH, moisture content, organic C, and total N. Species occurrences and their relative abundance data were used to estimate alpha and beta diversity. A total of 76 plant species from 29 families were recorded (Malvaceae, Fabaceae and Asteraceae being top dominants). Maximum flora was recorded in rainy season at both sites, higher at non-invaded sites in all seasons. Beta diversity followed similar trend, higher in rainy season and at non-invaded than invaded sites, highest being 13.2 at non-invaded site in rainy season. Dominants changed with site and season. Vegetation patches were distinct in drier seasons compared to rainy months. Soil organic carbon, total nitrogen and C : N ratios were high at invaded sites compared to non-invaded sites except in summer season. While higher diversity and higher similarity amongst different sites in rainy season indicated a homogenization impact in Indian dry tropical regions, higher diversity at non-invaded site suggested implication of diversity-reducing impact of tree invader Prosopis juliflora.

Impact of drought on vegetation over inner Mongolia autonomous region

Abstract In recent years, remote sensing technology has become an important tool for monitoring vegetation changes in semi-arid regions. By using data collected by satellites to calculate vegetation indices, researchers can track changes in vegetation density and productivity over time. This can help identify areas of potential desertification or degraded land degradation and develop management strategies to restore degraded ecosystems. The objectives of this paper are to use multi-temporal MODIS data to extract vegetation distribution characteristics and dynamics in Inner Mongolia Autonomous Region. This study summarized the rainfall data of Inner Mongolia Autonomous Region from 2000 to 2019, and found the driest year 2001 and the wettest year 2012. The NDVI data of 4 districts of Xingan League in 2001 and 2012 were selected for analysis, and the average NDVI value and standard deviation of the 4 districts were obtained. NDVI data was combined with elevation data and vegetation data for analysis. The relationship between precipitation and NDVI is helpful to understand the impact of drought on vegetation in Inner Mongolia and provide reference for regional environmental management.

Rainfall seasonality dominates critical precipitation threshold for the Amazon forest in the LPJmL vegetation model

Understanding the Amazon Rainforest's response to shifts in precipitation is paramount with regard to its sensitivity to climate change and deforestation. Studies using Dynamic Global Vegetation Models (DGVMs) typically only explore a range of socio-economically plausible pathways. In this study, we applied the state-of-the-art DGVM LPJmL to simulate the Amazon forest's response under idealized scenarios where precipitation is linearly decreased and subsequently increased between current levels and zero. Our results indicate a nonlinear but reversible relationship between vegetation Above Ground Biomass (AGB) and Mean Annual Precipitation (MAP), suggesting a threshold at a critical MAP value, below which vegetation biomass decline accelerates with decreasing MAP. We find that approaching this critical threshold is accompanied by critical slowing down, which can hence be expected to warn of accelerating biomass decline with decreasing rainfall. The critical precipitation threshold is lowest in the northwestern Amazon, whereas the eastern and southern regions may already be below their critical MAP thresholds. Overall, we identify the seasonality of precipitation and the potential evapotranspiration (PET) as the most important parameters determining the threshold value. While vegetation fires show little effect on the critical threshold and the biomass pattern in general, the ability of trees to adapt to water stress by investing in deep roots leads to increased biomass and a lower critical threshold in some areas in the eastern and southern Amazon where seasonality and PET are high. Our findings underscore the risk of Amazon forest degradation due to changes in the water cycle, and imply that regions that are currently characterized by higher water availability may exhibit heightened vulnerability to future drying.

Spatiotemporal Variations of Vegetation and Its Response to Climate Change and Human Activities in Arid Areas—A Case Study of the Shule River Basin, Northwestern China

The Shule River Basin (SRB) is a typical arid area in northwest China with a fragile ecology. Understanding vegetation dynamics and its response to climate change and human activities provides essential ecological and environmental resource management information. This study extracted fractional vegetation coverage (FVC) data from 2000 to 2019 using the Google Earth Engine platform and Landsat satellite images, employing trend analysis and other methods to examine spatiotemporal changes in vegetation in the SRB. Additionally, we used partial correlation and residual analyses to explore the response of FVC to climate change and human activities. The main results were: (1) The regional average FVC in the SRB showed a significant upward trend from 2000 to 2019, increasing by 1.3 × 10−3 a–1. The area within 1 km of roads experienced a higher increase of 3 × 10−3 a–1, while the roadless areas experienced a lower increase of 1.1 × 10−3 a–1. The FVC spatial heterogeneity in the SRB is significant. (2) Partial correlation analysis shows that the FVC correlates positively with precipitation and surface water area, with correlation coefficients of 0.575 and 0.744, respectively. A weak negative correlation exists between the FVC and land surface temperature (LST). FVC changes are more influenced by precipitation than by LST. (3) The contributions of climate change to vegetation recovery are increasing. Human activities, particularly agricultural practices, infrastructure development, and the conversion of farmland to grassland, significantly influence vegetation changes in densely populated areas. (4) The area changes of different land types are closely related to climate factors and human activities. Increased construction, agricultural activity, and converting farmland back to grassland have led to an increase in the area proportions of “impervious surfaces”, “cropland”, and “grassland”. Climate changes, such as increased rainfall, have resulted in larger areas of “wetlands” and “sparse vegetation”. These results provide valuable information for ecosystem restoration and environmental protection in the SRB.

Monitoring vegetation cover trends in the steppe region of western Algeria using MODIS imagery

The steppe region of Chehaima (Tiaret Province, northwestern Algeria) covers an area of 2,202 km², representing 10.94% of the total area of Tiaret. This study identified the ecological state of the area using a spatial theme from a 24-year synchronized moderate-resolution imaging spectroradiometer (MODIS) satellite image campaign (2000–2023). The adopted method consists of analyzing spectral indices (normalized difference vegetative index, low surface temperature (LST), and soil moisture index) from MODIS sensors (MOD13Q1), making it possible to evaluate the spatiotemporal dynamics of the vegetation in the study area and to identify regions degraded by several biotic and abiotic factors. The results show a vegetation cover rate of intense fluctuations in unfavorable conditions over 24 years. The percentage of plant growth recorded does not exceed 32%. The abundance of LST vegetation decreases when the LST exceeds 35°C, with a soil that has a water deficit. The De Martonne aridity index (<em>I</em>) classifies the study area as a lower semiarid bioclimatic zone. These indicators made it possible to determine the spatiotemporal dynamics of vegetation, which modifies the plant cover, leading to the loss of native species such as alfa <em>Stipa tenacissima</em> L. Defensive measures are necessary over large areas of the study area to allow successful protection of steppe rangelands through a sustainable conservation strategy, preserving endemic species, stabilizing dunes, and adopting the steppe rotation system.

Composition, structure and dynamics of poplar forests in the Lena Pillars National Park

This article presents the findings from research conducted on poplar forests within the Lena Pillars National Park. Prior to this study, there had been no detailed research on the poplar forests in the park; only general characteristicsand brief descriptions of forest types were available. The article provides a comprehensive description of tree stands, analyzes the ecological structure of the flora in poplar forests, examines the dynamics of floodplain vegetation, and traces the succession series in the floodplains of the Buotama, Kuranakh, and Labyya rivers within the National Park. At different stages of development, the forests formed by the poplar tree stand are serial (temporary) types, naturally progressing from rare-herb association, mix herb + Equisetum pretense + Calamagrostis langsdorffii (in young poplar stands) → mix herb + shrubs (middle-aged stands, ripening stands) → tall herb + shrub associations with spruce and larch (in ripening, and overmature forests). As the floodplain emerges, the development of poplar forests inevitably transitions to being replaced by coniferous forests. When the overmature poplar tree stand collapses, spruce and larchspruce and birch forests form in its place. Poplar forests in the Lena Pillars National Park are characterized by high productivity; forest stands develop according to Bonitat classes 3-4. Research on the taxation of poplar forests has allowed for the evaluation of the interdependence of different morphometric traits of poplar trees. The correlation has verified the existence of consistent relationships between specific tax indicators. The findings from the study will contribute to understanding the plant life and vegetation in Lena Pillars National Park and the poplar forests of Yakutia. This data can be used to evaluate how the vegetation in the park’s poplar forests may change in the future.

Late Holocene vegetation dynamics: degree and regional patterns of the Dark Ages woodland regeneration (ad 300–700) in the Netherlands

AbstractDuring the Dark Ages, which include the Late Roman period (ad 270–450) and the Early Middle Ages (ad 450–1050), large-scale vegetation development in northwest Europe was characterised by widespread regeneration of woodlands. This regeneration phase represents a break from the extensive reduction in woodland from human activities in late Holocene vegetation history. In the Netherlands, possible causes for this reversal can be found in a decreased human impact on the landscape, a colder and possibly wetter climate, and geomorphological changes. This paper presents a synthesis from 38 pollen records from a range of sites across the Netherlands, from which regional differences in the degree of woodland regeneration and vegetation composition before and during the Dark Ages have been identified. Both original data as well as vegetation abundance modelled by REVEALS were used to assess the regrowth of the woodland cover. The observed trends were considered in terms of the landscape setting and population estimates in order to disentangle the relative importance of these forcing factors. The results indicate that landscape and human impact were the most important factors determining the vegetation structure and changes to it. The pollen data show that in the Netherlands, the clearance of woodland in the Roman period followed by its regrowth afterwards were greatest in the river area. This can be linked to a high population density there during the Roman period followed by a strong decrease of population in the Dark Ages and to increased flooding.

Arrested Succession on Fire-Affected Slopes in the Krummholz Zone and Subalpine Forest of the Northern Limestone Alps

Fire in the Northern Alps is comparatively rare. Yet, previous human-ignited fire events in subalpine forests up to the treeline have triggered severe fire damage to vegetation and soil. Here, we investigate post-fire vegetation dynamics in the Northern Limestone Alps about 80 years after disturbance. We observed higher species richness in burned compared to unburned vegetation and clearly distinct floristic communities emerging after fire-driven forest removal, with several alpine specialist species uniquely found in the burned subalpine sites. The functional composition of vegetation was also distinct, with higher relative forb cover in burned plots. This difference was likely driven by disturbance-related environmental changes, such as increased light availability, offering safe sites for subalpine and alpine species. Due to a general lack of tree encroachment, we consider this a case of arrested succession after fire. We conclude that the recovery of fire-affected subalpine forests is modulated by complex interactions of climatic and biotic filters producing extreme site conditions, controlling the recolonization of the disturbed areas by forest species while providing safe sites for the establishment of a rich subalpine and alpine low-statured flora. The coupling of disturbance and abiotic filters makes high-elevation treeline ecotones very vulnerable to climate change.

Vegetation Dynamics Assessment: Remote Sensing and Statistical Approaches to Determine the Contributions of Driving Factors

Vegetation Dynamics Assessment: Remote Sensing and Statistical Approaches to Determine the Contributions of Driving Factors

Holocene vegetation and flora dynamics of the west Cork/Kerry region, south-western Ireland

AbstractSediments from a small lake, Loch Beag, in Barrees, Beara peninsula, south-western Ireland, provide a record of vegetation history that spans most of the Lateglacial and Holocene (14–0.43 ka). The detailed part of the record relates to the Holocene, which is the focus of this paper. The investigations carried out include pollen and macrofossil analyses, loss-on-ignition measurements and 14C dating. As well as providing records for tree and shrub taxa, and especially Pinus, Quercus, Ulmus, Fraxinus and Taxus, other taxa mainly with Atlantic and/or Lusitanian distributions are also considered. These include Arbutus unedo (strawberry tree) and fern species such as Osmunda regalis, and the filmy ferns Hymenophyllum tunbrigense, H. wilsonii and Trichomanes speciosum (Killarney fern). Detailed records for a suite of bog/heath taxa, including ericoid species (Erica tetralix and E. cinerea), Narthecium ossifragum, Hypericum elodes and Myrica gale, are presented. The results of 14C dating of bog-pines from western Ireland are summarised. Results of other investigations, including key Holocene pollen diagrams, and charcoal and fossil-wood records from archaeological excavations that relate mainly to the Bronze Age in the wider west Cork/Kerry region, are reviewed. Vegetation dynamics, human impact and plant biogeography are discussed in the light of the considerable data now available for the region.

Vegetation response to large-scale mountain excavation and city construction projects on the Loess Plateau of China

Since 2012, the “Mountain Excavation and City Construction” (MECC) project has been implemented extensively on the Loess Plateau of China, transforming gullies into flat land for urban sprawl by leveling loess hilltops to fill in valleys. However, this unprecedented human activity has caused widespread controversy over its unknown potential ecological impacts. Quantitative assessment of the impacts of the MECC project on the vegetation is key to ecological management and restoration. Taking the largest MECC project area on the Loess Plateau, Yan'an New District (YND), as the study area, this study investigated the spatiotemporal pattern of vegetation dynamics before and after the implementation of the MECC project using a multitemporal normalized difference vegetation index (NDVI) time series from 2009 to 2023 and explored the response of vegetation dynamics to the large-scale MECC project. The results showed that the vegetation dynamics in the YND exhibited significant spatial and temporal heterogeneity due to the MECC project, with the vegetation in the project-affected areas showing rapid damage followed by slow recovery. Vegetation damage occurred only in the project-affected area, and 84 % of these areas began recovery within 10 years, indicating the limited impact of the large-scale MECC project on the regional vegetation. The strong correlation between vegetation dynamics and the MECC project suggested that the destruction and recovery of vegetation in the project-affected areas was mainly under anthropogenic control, which highlights the importance of targeted ecological policies. Specifically, the MECC project induced local anthropogenic damage to the plant population structure during the land creation period, but regeneration and rational allocation of the vegetation were achieved through urbanization, gradually forming a new balanced ecological environment. These findings will contribute to a full understanding of the response of vegetation to such large-scale engineering activities and help local governments adopt projects or policies that facilitate vegetation recovery.

The impact of socioeconomic factors on vegetation restoration in karst regions: A perspective beyond climate and ecological engineering

Socioeconomic factors are important parameters that affect vegetation changes in karst areas. Previous studies primarily focused on ecological engineering when analyzing the impact of human activities on vegetation restoration, whereas the impact of socioeconomic factors has been less studied. The study employs structural equation modeling and geographically weighted regression to quantitatively assess the impact of socioeconomic factors on vegetation dynamics within karst regions, with a focus on the county level. The results showed a significant upward trend in both the Enhanced Vegetation Index and Net Primary Productivity across China's humid karst regions from 2000 to 2020. Among the socioeconomic factors, non-farm economy and rural economy had a positive effect on vegetation change, with maximum path coefficients of the structural equation model of 0.79 and 0.64, respectively; whereas population pressure had a negative impact with a minimum path coefficient of −0.80. Over time, the positive impact of rural economy on vegetation restoration showed an increasing trend, and the path coefficient increased from-0.92 to 0.64; in turn, non-farm economy and population pressure showed a decreasing trend. Moreover, because they were affected by the heterogeneity of the karst mountain environment, the impact of various socioeconomic factors on vegetation restoration had obvious spatial non-stationarity. The results of this study will promote our understanding of the mechanism underlying vegetation change in humid karst areas and provide scientific reference for ensuring the sustainability of the ecological effects in these areas.

Spatio-temporal dynamics of fairy circles in Namibia are driven by rainfall and soil infiltrability

ContextNamibia’s fairy circles (FCs) form an extraordinary vegetation pattern along the Namib Desert. Recent evidence from multiple fieldwork activities is increasingly supporting the view that FCs result from biomass-water feedbacks and plant self-organization.ObjectivesTo shed light on these biomass-water feedbacks, we focused here on a temporal analysis of the spatial FC patterns with regard to vegetation response after rainfall events.MethodsWe analyzed the distribution of FCs in 10 drone-mapped study plots of the Namib and related their spatial patterns to the soil infiltrability. Additionally, we mapped three plots repeatedly during the rainfall seasons 2020–2023 to assess how the emerging grasses within FCs changed the FC patterns after rainfall.ResultsWe found that the most regular, spatially periodic, FCs occurred in areas with deep aeolian sands where rain water infiltrates very quickly and homogenously across the study plot, which enables the most symmetric competitive interactions between the grasses. After ample rainfall following a drought period, between 58 and 34% of all mature FCs revegetated. These 1092 closing FCs were 73 times more than the 15 new FCs that formed during the same time. The closing FCs occurred in areas where there was locally a higher density of FCs, which act as underground water sources for the surrounding grasses.ConclusionsOur study shows that the dynamic vegetation response to rainfall and soil water is the key driver of the FC patterns. Overall, the research underlines that Namibia’s fairy circles are a self-organized emergent vegetation pattern that is driven by biomass-water feedbacks and the competition of grasses for limiting water resources.

Vegetation Dynamics since the Last Glacial Maximum in Central Yunnan, Southwest China

Vegetation Dynamics since the Last Glacial Maximum in Central Yunnan, Southwest China