Long-term Vegetation Dynamics Research Articles

Assessment of climatic and anthropogenic influences on vegetation dynamics in China: a consideration of climate time-lag and cumulative effects.

Determining the factors that drive vegetation variation is complicated by the intricate interactions between climatic and anthropogenic influences. Neglecting the short-term time-lag and cumulative effects of climate on vegetation growth (i.e., temporal effects) exacerbates the uncertainty in attributing long-term vegetation dynamics. This study evaluated the climatic and anthropogenic influences on vegetation dynamics in China from 2000 to 2019 by analyzing normalized difference vegetation index (NDVI), temperature, precipitation, solar radiation, and ten anthropogenic indicators through linear regression, correlation, multiple linear regression (MLR), residual, and principal component analyses. Across most regions, growing season NDVI (G-NDVI) exhibited heightened sensitivity to climatic variables from earlier periods or from both earlier and current periods, signaling extensive temporal climatic effects. Constructing new time series for temperature, precipitation, and solar radiation from 2000 to 2019, based on the optimal vegetation response timing to each climatic variable, revealed significant correlations with G-NDVI across 27.9%, 26.7%, and 23.3% of the study area, respectively. Climate variability and anthropogenic activities contributed 45% and 55% to the G-NDVI increase in China, respectively. Afforestation significantly promoted vegetation greening, while agricultural development had a marginally positive influence. In contrast, urbanization negatively impacted vegetation, particularly in eastern China, where farmland conversion to constructed land has been prevalent over the past two decades. Neglecting temporal effects would significantly reduce the areas with robust MLR models linking G-NDVI to climatic variables, thereby increasing uncertainty in attributing vegetation changes. The findings highlight the necessity of integrating multiple anthropogenic factors and climatic temporal effects in evaluating vegetation dynamics and ecological restoration.

Atlas of the Oman pollen flora – Pollen morphology of the arid Arabian Peninsula vegetation

Atlas of the Oman pollen flora – Pollen morphology of the arid Arabian Peninsula vegetation

Revealing the long-term impacts of plant invasion and reclamation on native saltmarsh vegetation in the Yangtze River estuary using multi-source time series remote sensing data

Revealing the long-term impacts of plant invasion and reclamation on native saltmarsh vegetation in the Yangtze River estuary using multi-source time series remote sensing data

Accumulation of pathogens in soil microbiome can explain long-term fluctuations of legumes in a grassland community.

All plant populations fluctuate in time. Apart from the dynamics imposed by external forces such as climate, these fluctuations can be driven by endogenous processes taking place within the community. In this study, we aimed to identify potential role of soil-borne microbial communities in driving endogenous fluctuations of plant populations. We combined a unique, 35-yr long abundance data of 11 common plant species from a species-rich mountain meadow with development of their soil microbiome (pathogenic fungi, arbuscular mycorrhizal fungi and oomycetes) observed during 4 yr of experimental cultivation in monocultures. Plant species which abundance fluctuated highly in the field (particularly legumes) accumulated plant pathogens in their soil mycobiome. We also identified increasing proportion of mycoparasitic fungi under highly fluctuating legume species, which may indicate an adaptation of these species to mitigate the detrimental effects of pathogens. Our study documented that long-term fluctuations in the abundance of plant species in grassland communities can be explained by the accumulation of plant pathogens in plant-soil microbiome. By contrast, we found little evidence of the role of mutualists in plant population fluctuations. These findings offer new insights for understanding mechanisms driving both long-term vegetation dynamics and patterns of species coexistence and richness.

Looking at the modern landscape of submediterranean Greece through a palaeoecological lens

The importance of understanding the long-lasting legacy of past land use on modern ecosystems has long been acknowledged. However, the magnitude and persistence of such legacies have been assessed only occasionally. Northern Greece has been a gateway of farming into mainland Europe during the Neolithic, thus providing a perfect setting to assess the potential impact of land-use history on present-day ecosystems. Additionally, the marked Holocene climatic variability of the southern Balkans makes it possible to investigate climate-vegetation-land use interactions over long timescales. Here, we have studied a sediment record from Limni Vegoritis (Northern Greece) spanning the past ∼9000years using palaeoecological proxies (pollen, spores, stomata, microscopic charcoal). We aimed to reconstruct long-term vegetation dynamics in submediterranean Greece, to assess the environmental factors controlling them and to establish the legacies of the long history of land use in the modern landscape. We found that the Early Holocene afforestation, mainly oak woodlands, was delayed because of suboptimal moisture conditions. Later, colder and drier conditions during the rapid climate change centred around the '8.2 ka event' triggered woodland opening and the spread of wooded (Juniperus) steppe vegetation. First indicators of farming activities are recorded during this period, but their abundances are too low to explain the concurrent large deforestation episode. Later, pinewoods (probably dominated by Pinus nigra) with deciduous Quercus spread and dominated the landscape for several millennia. These forests experienced repeated multi-centennial setback-recovery episodes associated with land-use intensification, but pines eventually declined ∼2500-2000years ago during Classical times under heavy land use comprising intense pastoralism. This was the starting point for the present-day landscape, where the main 'foundation' taxon of the ancient forests (Pinus cf. nigra) is missing, therefore attesting to the strong imprint that historical land use has left on the modern landscape.

Unraveling resilience amidst degradation: Recurring loss of freshwater marshes in the Paraná River Delta, Argentina

Unraveling resilience amidst degradation: Recurring loss of freshwater marshes in the Paraná River Delta, Argentina

Holocene Vegetation Dynamics Revealed by a High-Resolution Pollen Record from Lake Yangzonghai in Central Yunnan, SW China

Long-term regional vegetation dynamics is essential for the understanding of past land cover changes. High-resolution pollen analysis of a 1020 cm core from a large lake, Lake Yangzonghai (YZH), in central Yunnan, SW China, was conducted to reveal regional vegetation dynamics in the lake catchment over the past 13,400 years. Pollen record, principal component analysis (PCA) of pollen percentages of major arboreal taxa, and plant abundances estimated from the “Regional Estimates of VEgetation Abundance from Large Sites” (REVEALS) model show five successional stages of vegetation dynamics since 13,400 cal. a BP: regional vegetation with high coverages in the lateglacial (13,400–11,400 cal. a BP) was dominated by evergreen broadleaved forest (EBF) and deciduous broadleaved forest (DBF), together with some grass meadows and marshes; pine forest and alder forest expanded in the early Holocene (11,400–9000 cal. a BP) when vegetation coverages were still high; regional vegetation with low coverages was dominated by sweetgum forest, together with some pine forest during the mid-Holocene (9000–4200 cal. a BP); more pine forest, grass meadows and marshes occupied the lake catchment during the late Holocene (4200–800 cal. a BP), when vegetation coverages were higher than the average of the past 13,400 years; regional vegetation with low coverage was dominated by grass meadows and marshes, great deforestation happened in the last 800 years. Regional vegetation dynamics over the past 13,400 years in the Lake YZH catchment was the result of regional vegetation response to climate changes during the lateglacial and early–mid Holocene, and to human activities mainly during the late Holocene.

Long-term changes in vegetation and land use in mountainous areas with heavy snowfalls in northern Japan: an 80-year comparison of vegetation maps

Comparison of old and new vegetation maps is an effective way to detect vegetation dynamics. Recent developments in computer technology have made it possible to accurately compare old paper vegetation maps with current digitized vegetation maps to reveal long-term vegetation dynamics. Recently, a 1:50,000 scale vegetation map of the Hakkoda Mountains in northern Japan, located in the ecotone of cool temperate and subalpine forests in northern Japan under an East Asian monsoon climate, from 1930 was discovered. We compared the 1930s vegetation map with the most recent 2010 vegetation map to test the following hypotheses: 1) the occurrence of upward expansion of the upper limit of cool-temperate deciduous forests, and 2) whether designation as a national park in 1936 would have reduced forestry and land use, expanded beech forests, and cool-temperate deciduous forests. To compare vegetation changes, 67 types of vegetation legends for the 1930 and 2010 maps were unified to 21 based on plant species composition. Consequently, vegetation has changed substantially over the past 80 years. 1) In the subalpine zone above 1,000 m, the coniferous forest area decreased by half. In the cool temperate zone below 1,000 m, the area of beech forests increased 1.48 times, and some of them could be shifted upwards, replacing subalpine fir forests in the lower part of the subalpine zone. 2) In areas below 700 m, deciduous oak forests once used as thickets were almost halved. Instead, climax and beech forests expanded. However, we also found that even after the area was declared a national park, oak forests were cleared and converted to commercial forests such as cedar plantations, cattle ranches, and horse pastures in some areas. These results will be useful for future ecosystem and biodiversity research/conservation and will provide baseline information for climate change adaptation policies.

Long-Term Monitoring of Oil Spill Impacted Vegetation in the Niger Delta Region of Nigeria: A Google Earth Engine Derived Vegetation Indices Approach

New and emerging cases of oil spill incidents are reported almost on a weekly basis in the Niger Delta region of Nigeria with accusations and counter-accusations as to the claims made by interested parties on perceived impacts of the spills on the environment and its associated constituents. This study applied the capabilities offered by the Google Earth Engine (GEE) platform to monitor long-term vegetation dynamics as a result of exposure to pollution emanating from crude oil spills in the Niger Delta region of Nigeria. The capabilities offered by GEE provide a platform for rapid access to big data for the assessment of environmental change, especially in the Niger Delta with its difficult terrain and security concerns. This study considered oil spill incidents in vegetated terrestrial locations in the Niger Delta across ten years. Fifteen locations spread across the region with oil spill incidents identified as large incidents being selected (>50 <5000bbl). Results of the statistical analysis performed on the vegetation indices data generated from GEE suggest that the analysis of long-term vegetation indices using GEE can provide a broad view of the impact of oil spills on vegetation over time if the spills are relatively large or the spills are repetitive. However, when the spills were relatively small, there was no statistically significant variation in the spectral signatures of the vegetation over time. This suggests that for large spills, GEE-derived vegetation indices can be a very useful synoptic tool in monitoring oil spill occurrence and impact on vegetated terrestrial environments in the Niger Delta and elsewhere where environmental accessibility is a challenge.

An 8500-year history of climate-fire-vegetation interactions in the eastern maritime black spruce–moss bioclimatic domain, Québec, Canada

ABSTRACT The eastern, maritime portion of the black spruce – moss bioclimatic domain in Québec (Canada) is characterized by large wildfires with low occurrence. However, it is still poorly understood how climate–fire interactions influenced long-term vegetation dynamics in the boreal forest of eastern Québec. The long-term historical climate–fire–vegetation interactions in this region were investigated using a multiproxy (chironomids, charcoal, and pollen) paleoecological analysis of an 8500-year sediment core. Chironomid-inferred August air temperatures suggest that the warm Holocene Thermal Maximum (HTM; between ca. 7000–4000 cal yr BP) shifted to the cooler Neoglacial period (4000 cal yr BP to present), consistent with other temperature reconstructions across Québec. The shift to spruce-moss forest dominance around 4800 cal yr BP occurred nearly a thousand years before the climatic shift to the Neoglacial period and rather coincided with a shift from frequent low-severity small fires to infrequent but large and severe fire events. Our results suggest that long-term changes in the summer temperature are probably not the main factor controlling fire and vegetation dynamics in eastern Québec. It seems that, throughout the postglacial period, summer temperatures never fell below a threshold that could have induced a significant vegetation response.

Urban and Peri-Urban Vegetation Monitoring Using Satellite MODIS NDVI Time Series, Singular Spectrum Analysis, and Fisher–Shannon Statistical Method

The purpose of this work was to evaluate the potential of Singular Spectrum Analysis (SSA) and the Fisher–Shannon method to analyse NDVI MODIS time series and to capture and estimate inner vegetation anomalies in forest covers. In particular, the Fisher–Shannon method allows to calculate two quantities, the Fisher Information Measure (FIM) and the Shannon entropy power (SEP), which are used to characterise the complexity of a time series in terms of organisation/disorder. Pilot sites located both in urban (Milano, Torino, and Roma) and peri-urban areas (Appia Park, Castel Porziano, and Castel Volturno) were selected. Among the six sites, Roma, Castel Porziano, and Castel Volturno are affected by the parasite Toumeyella parvicornis. The time series was analysed using the products available in Google Earth Engine. To explore and characterise long-term vegetation dynamics, the time series was analysed using a multistep processing chain based on the (i) normalisation of the satellite time series, (ii) removal of seasonality and any other periodical cycles using SSA, (iii) analysis of the de-trended data using the Fisher–Shannon statistical method, and (iv) validation through comparison with independent data and ancillary information. Our findings point out to a clear discrimination between healthy and unhealthy sites, being the first (Milano, Torino, Appia) characterised by a larger FIM (lower SEP) and the second (Roma, Castel Porziano, Castel Volturno) by a lower FIM (larger SEP). The results of the investigations showed that the use of the SSA and Fisher–Shannon statistical methods coupled with the NDVI time series of the MODIS satellite made it possible to effectively identify and characterise subtle but physically significant signals veiled by seasonality and annual cycles.

Modeling the long-term vegetation dynamics of a backbarrier salt marsh in the Danish Wadden Sea

Modeling the long-term vegetation dynamics of a backbarrier salt marsh in the Danish Wadden Sea

Spatially explicit, quantitative reconstruction of past vegetation based on pollen or charcoal data as a tool for autecology of trees

ContextThe determination of autecological preferences based on long-term vegetation dynamics is hampered by the lack of realistic estimates for past occurrence and abundance patterns. Palaeoecological record has still rather character of points than spatially continuous maps.ObjectivesTo infer long-term autecological preferences of trees from reconstructed vegetation. Compare reconstructions based on pollen and charcoals.MethodsWe employed to the regional training set of 58 sites the Extended Downscaling Approach (EDA) using nine topographic factors clustered in 8 habitat classes, data on pollen productivity estimates, fossil pollen, charcoal sequences from soil and archaeological contexts. Based on abundances and habitat preferences from the last 9 millennia, we calculated the autecological preferences of tree taxa, using multivariate statistics.ResultsThe significant spatiotemporal patterns between soil-charcoal and pollen-based EDA validated the reconstruction, the use of both records in the EDA, and the EDA model. One of the topographic indices—vertical distance to channel network—evidenced the following: the closest taxon to the groundwater is Picea; Abies, Betula, Pinus and Quercus have intermediate distances; Fagus grows far from the channel network and Corylus even further.ConclusionsThe EDA model linked past forest composition to realistic topography. Such a spatially explicit reconstruction produced by our new algorithm allows inferring the relationship between past plant communities and environmental variables. The long-term preferences of tree species to habitat characteristics match their current autecological demands. This might be a breakthrough in quantitative plant paleoecology.

Long-term vegetation response to rainfall seasonality and fire in the heathlands and shrublands of the Cape Floristic Region (SW South Africa)

Mediterranean environments are biodiversity hotspots in which strongly seasonal winter rainfall regimes and fire play major roles in driving ecosystem dynamics. Global predictions forecast unreliability of winter rainfall and increases in summer rainfall that are expected to result in major changes in community structure. Mediterranean systems are difficult to model, and although ecophysiological responses can be studied at observational timescales, a long-term understanding is necessary to address uncertainties and refine predictive models at landscape scales. Here we provide a ∼ 1100 year-long palaeoecological reconstruction of vegetation (palynology), fire (sedimentary charcoal) and sedimentological change at a site adjacent to a multi-annual rainfall manipulation experiment designed to test plant population and community responses to altered seasonal regimes in the Greater Cape Floristic Region hotspot (southwestern Africa). We use these data to test whether long-term vegetation dynamics are controlled by changes in rainfall seasonality. We conclude that vegetation dynamics correlate with centennial-scale seasonality fluctuations, with transitions between two ecologically distinct fine-leaved shrub communities. These transitions are consistent with results of responses to experimental manipulations of summer rainfall. This study demonstrates the value of ecophysiological research in interpreting palaeoecological reconstructions and scaling up the results of observational research to answer long-term questions about environmental change.

The Role of Protected Areas in Mitigating Vegetation Disturbances on the Qinghai-Tibetan Plateau

Long-term vegetation dynamics with satellite observations can provide valuable insights into natural variation in ecosystems and quantify disturbances associated with external pressures. Monitoring vegetation dynamics within protected areas (PAs) is essential, given their crucial role in protecting biodiversity and maintaining ecosystem integrity. In this study, using the normalized difference vegetation index (NDVI) and Breaks For Additive Seasonal and Trend (BFAST)model, we detected vegetation dynamics especially abrupt changes inside nature reserves (NRs, the primary type of PAs) on the Qinghai-Tibetan Plateau from 2000 to 2020. We then applied the matching approach and postmatching regression to evaluate the effect of NRs on natural vegetation with average NDVI, NDVI slope, and the number of abrupt changes. Our results showed that 78.97% of the vegetation within NRs exhibited greening trends. In addition, 29.15% of the area inside of the NRs experienced 1 or more abrupt changes, with the major change type interrupted greening (15.96%), followed by greening to browning (6.27%) and browning to greening (4.00%). The NRs significantly reduced the frequency of disturbances, and older NRs also showed a higher value of average NDVI compared to those in matched unprotected areas. Postregression models indicated that vegetation in newer NRs tended to be more vulnerable to disturbances and stricter NR management could benefit vegetation enhancement. Our analysis offers a new approach to vegetation dynamic monitoring that considers short-term disturbances. The findings of this work can help better understand effectiveness of PAs on ecosystem protection and offer practical guidance to future PAs management.

Sedimental pollen records in the northern South China Sea and their paleoenvironmental significance

Studies on the reconstruction of long-term climatic and vegetation dynamics around the northern South China Sea (SCS) are limited. Therefore, this study was conducted to get a clear understanding of the paleoenvironmental significance around the Taiwan Strait in northern SCS. The chronology was based on the accelerator mass spectrometry (AMS) 14C dates of mixed planktonic foraminifera, then we compared and cross-validated the age–depth model based on the grain-size analysis and foraminifera data. Palynomorph data, including percentages and concentrations based on marine sediment cores (WQZK1, WQZK2, and WQZK3), were used to reconstruct the history of vegetation and climate changes and identify the provenance and transport mechanisms of pollen and spores. The findings indicated that fern spores dominated the interglacial period, suggesting intense summer monsoons during warm periods in marine isotope stages (MIS) 5–MIS 1. During MIS 5a, tropical and subtropical conifers with temperate components dominated, indicating the climate was comparatively warm at an increasing sea level. The lowest sea level subtly proved cooler and wetter climate, subsequently affecting a drastic increase of Pinus during MIS 4. Tropical and subtropical conifers dominated during the MIS 3, and the sea level increased comparatively to MIS 4, indicating warmer climate conditions. Pinus pollen and fern spores dominated MIS 1, implying that the paleoenvironment was comparable to the present day. Therefore, this study supports previous studies on the northern SCS region and suggests that a combination of pollen with other proxies provides a better understanding of vegetation and climatic dynamics in the past.

A chronologically reliable record of 17,000 years of biomass burning in the Lake Victoria area

A chronologically reliable record of 17,000 years of biomass burning in the Lake Victoria area

Vegetation Dynamics under Rapid Urbanization in the Guangdong–Hong Kong–Macao Greater Bay Area Urban Agglomeration during the Past Two Decades

Detection of long-term vegetation dynamics is important for identifying vegetation improvement and degradation, especially for rapidly urbanizing regions with intensive land cover conversions. The Guangdong–Hong Kong–Macao Greater Bay Area (GBA) urban agglomeration has experienced rapid urbanization during the past decades with profound impacts on vegetation, so there is an urgent need to evaluate vegetation dynamics across land use/cover change (LUCC). Based on the normalized difference vegetation index (NDVI) during 2001–2020, we used coefficient of variation, Theil–Sen median trend analysis, and Hurst exponent to analyze the spatiotemporal change and future consistency of vegetation growth among the main LUCC in the GBA. Results demonstrated that low NDVI values with high fluctuations were mainly distributed in the central urban areas, whereas high NDVI values with low fluctuations were primarily located in the peripheral hilly mountains. The area-averaged NDVI showed an overall increasing trend at a rate of 0.0030 year−1, and areas with vegetation improvement (82.99%) were more than four times those with vegetation degradation (17.01%). The persistent forest and grassland and the regions converted from built-up to vegetation displayed the most obvious greening; NDVI in over 90% of these areas showed an increasing trend. In contrast, vegetation browning occurred in more than 60% of the regions converted from vegetation to built-up. Future vegetation change in most areas (91.37%) will continue the existing trends, and 80.06% of the GBA was predicted to develop in a benign direction, compared to 19.94% in a malignant direction. Our results contribute to in-depth understanding of vegetation dynamics during rapid urbanization in the GBA, which is crucial for vegetation conservation and land-use optimization.

Understanding the Long-Term Vegetation Dynamics of North Korea and Their Impact on the Thermal Environment

In response to widespread deforestation, North Korea has restored forests through national policy over the past 10 years. Here, the entire process of forest degradation and restoration was evaluated through satellite-based vegetation monitoring, and its effects were also investigated. The vegetation dynamics of North Korea were characterized from 1986 to 2021 using the Landsat satellite 5–7, after which we evaluated the effect of vegetation shifts through changes in surface temperature since the 2000s. Vegetation greenness decreased significantly from the 1980s to the 2000s but increased in recent decades due to forest restoration. During the deforestation period, vegetation in all areas of North Korea tended to decrease, which was particularly noticeable in the provinces of Pyongannam-do and Hamgyongnam-do. During the forest restoration period, increases in vegetation greenness were evident in most regions except for some high-mountainous and developing regions, and the most prominent increase was seen in Pyongyang and Pyongannam-do. According to satellite-based analyses, the land surface temperature exhibited a clear upward trend (average slope = 0.13). However, large regional differences were identified when the analysis was shortened to encompass only the last 10 years. Particularly, the correlation between the area where vegetation improved and the area where the surface temperature decreased was high (−0.32). Moreover, the observed atmospheric temperature increased due to global warming, but only the surface temperature exhibited a decreasing trend, which could be understood by the effect of vegetation restoration. Our results suggest that forest restoration can affect various sectors beyond the thermal environment due to its role as an enhancer of ecosystem services.

Assessing Changes in Mountain Treeline Ecotones over 30 Years Using CNNs and Historical Aerial Images

Historical black-and-white (B&W) aerial images have been recognized as an important source of information for assessing vegetation dynamics. However, the use of these images is limited by the lack of multispectral information, as well as by their varying quality. It is therefore important to study and develop methods that are capable of automatic and accurate classification of these B&W images while reducing the need for tedious manual work. The goal of this study was to assess changes over 30 years in woody vegetation cover along alpine treeline ecotones using B&W aerial images from two time points. A convolutional neural networks model was firstly set up based on three structure classes calculated from Airborne Laser Scanning data using the B&W aerial images from 2010. Then, the model was improved by active addition of training samples of those that were wrongly predicted from historical B&W aerial images from 1980. A comparison with visual image interpretation revealed generally high agreement for the class “dense forest” and lower agreement for the class “group of trees”. The study illustrates that vegetation changes at the treeline ecotone can be detected in order to assess areawide long-term vegetation dynamics at a fine spatial resolution.