Major Vegetation Types Research Articles

Biological-based and remote sensing techniques to link vegetative and reproductive development and assess pollen emission in Mediterranean grasses

Connecting the signals of the vegetative and reproductive cycles of plants using large-scale phenological techniques is not always an easy task, and this complexity increases considerably when analysing the plant life cycle in grasses, due to the ubiquity and diversity of this taxonomic family. This work integrates remote sensing techniques (NDVI from satellite remote sensing data and greenness from near-surface imagery) and biological-based techniques (airborne pollen monitoring and field observations and sampling) to analyse phenological patterns and productivity in grass-dominated vegetation types. We aim to answer two main applied and unanswered questions; i) how are the specific phases of vegetative and reproductive cycles in grasses linked at the species and plant community level? and ii) which grass-dominant habitats are the major contributors of grass pollen emission to the atmosphere at the plant community level? The multi-scale integration and validation of large-scale methods such as satellite remote sensing data and aerobiological monitoring using high-resolution or field phenological techniques is recommended. The results clearly support the hypothesis that the highest rates of grass pollen emission are successively produced when the major grass-dominated vegetation types go through the final phases of vegetative development during their biological senescence or equivalent phases. At the plant community level, natural and semi-natural grass-dominated vegetation types, rather than grass cropland habitats, constitute the major sources of pollen emission. The major contributors to the grass pollen emission at the species level are also identified. Finally, a positive relationship between year-to-year primary productivity (measured as annual sum or maximum NDVI) and pollen production (measured as airborne pollen intensity) was observed at the community level. This is a very timely study, as the availability of remote sensing data is increasing interest in generating enhanced forecasting model of allergenic airborne pollen.

Microhabitat variables influencing the presence and abundance of birds in floodplain grassland of the lower Ganges and Brahmaputra rivers, Bangladesh

Grassland bird communities are likely declining in all major grassland ecosystems globally due to habitat loss and modification, yet knowledge of the status of many tropical grassland bird communities is relatively poor. This study investigated the bird community structure and its associations with vegetation characteristics and potential human impacts in seasonal floodplain grassland along the lower Ganges and Brahmaputra Rivers, Bangladesh (part of the Indo-Gangetic Plain) during 2018–2019 through point counts of birds combined with vegetation surveys. Bird responses were assessed by diversity indexes, non-metric multidimensional scaling ordination and linear models. Results show that the total resident bird community (31 grassland specialists, 34 generalists and 10 waterbirds) overlapped among the four major vegetation types in the study area (forbs and bushes, Saccharum sp., Cynodon sp. and cropland). The diversity of the total bird community increased with cover of forbs and bushes, while the overall diversity of grassland specialists (those adapted to and reliant on some variety of grassland habitat for part or all of their life cycle whether feeding or breeding.) increased with Saccharum sp. cover but decreased with increased crop cover. The diversity of the total bird community and all grassland specialist birds showed no variation with vegetation height. However, the abundance of grassland specialists showed a strong increase with increases in vegetation height. Among the grassland specialists, nine species that were entirely dependent on tall grasses for breeding were considered as obligate tall grass breeders. The abundance of these tall grass breeders decreased with greater cover of both Cynodon sp. and crops but increased with greater cover of Saccharum sp. The retention of vegetation with heights > 150 cm was therefore important to conservation and management of this community. Regular seasonal herding of cattle in these floodplain grasslands was widespread and it was therefore difficult to compare grazed with ungrazed areas. The diversity of neither the total bird community nor the overall grassland specialists showed any association with grazing intensity. However, grazing impacted negatively on the abundance of obligate tall grass breeders. Limited grass harvesting increased the overall diversity of the grassland specialist bird community. The estimated density of nine species of obligate tall grass breeders ranged from 0.19 to 4.41 birds/ha. Continuing rapid agricultural expansion was observed and is a prominent threat to these birds. More habitat-specific information and monitoring are required to quantify risks and aid conservation planning.

Plant traits and community composition drive the assembly processes of abundant and rare fungi across deserts.

The difference in community assembly mechanisms between rare and abundant fungi in deserts remains unknown. Hence, we compared the distribution patterns of abundant and rare fungi, and assessed the factors driving their assembly mechanisms across major vegetation types (shrubby desert, semi-shrubby and dwarf semi-shrubby desert, dwarf semi-arboreous desert, and shrubby steppe desert) of Chinese deserts. We assessed abundant and rare fungal subcommunities base on the sequencing data of fungal ITS data. Abundant fungal assembly was more affected by neutral processes than the rare. Null model and VPA analysis indicated that heterogeneous selection dominated rare sub-communities, whereas abundant fungal assembly was mainly determined by heterogeneous selection, dispersal limitation and other, unknown processes together. As a result, abundant sub-communities exhibited a higher species turnover rate than the rare. Hierarchical partitioning analysis indicated that soil conditions and plant attributes drove the assembly processes of abundant and rare fungi, respectively. Meanwhile, the relative strength of different assembly processes differed significantly among four vegetation types. In addition, we found that plant functional traits and composition played more critical roles in shaping the assembly processes of rare fungi than those of abundant fungi. Taken together, our findings collectively suggest that rare and abundant fungi exhibit differential ecological patterns that are driven by distinct assembly processes in deserts. We emphasize that the assembly processes of abundant and rare fungi are dependent on different abiotic and biotic factors in desert ecosystems.

Prefire Vegetation Structure of High Severity Wildfires in Nonherbaceous‐Dominated Rangelands in the Western United States

AbstractHigh severity rangeland wildfires have enormous negative impacts on human safety and infrastructure and may have long‐term consequences on ecosystem structure, function, and services, across the vast rangelands in the western United States. We explored prefire vegetation structure of all high severity wildfires, as well as associated areas with low and moderate burn severity, in nonherbaceous‐dominated rangelands in western United States from 1985 to 2018, based on fractional cover of annual forbs and grasses, perennial forbs and grasses, shrubs and trees from the Rangeland Analysis Platform. These wildfires were grouped into nine clusters using Expectation Maximization algorithms and patterns of prefire vegetation structure and the major vegetation types were assessed. High woody cover is a common characteristic of the prefire vegetation structure. Four of the clusters, which accounted for more than 70% of the areas of high severity wildfires, were characterized by high (∼50%) woody cover in prefire vegetation structure. The areas with high severity burns also had significantly higher woody cover than the areas with low or moderate severity burns in eight of the nine clusters. Some of these ecosystems can have abundant fine fuel, structural connectivity such as fuel laddering, and/or highly flammable materials, which can facilitate the ignition of the woody crowns, leading to high severity wildfires. Management strategies (such as prescribed burning) that can decrease woody cover and reduce standing dead vegetation and fuel laddering could be effective in reducing the risk and extent of high severity wildfires on rangelands in the western United States.

Functional Diversity in Woody Organs of Tropical Dry Forests and Implications for Restoration

Tropical dry forests (TDFs) represent one of the most diverse and, at the same time, most threatened ecosystems on earth. Restoration of TDFs is thus crucial but is hindered by a limited understanding of the functional diversity (FD) of original communities. We examine the FD of TDFs based on wood (vessel diameter and wood density) and bark traits (total, inner, and outer bark thicknesses) measured on ~500 species from 24 plant communities and compare this diversity with that of seven other major vegetation types. Along with other seasonally dry sites, TDFs had the highest FD, as indicated by the widest ranges, highest variances, and largest trait hypervolumes. Warm temperatures and seasonal drought seem to drive diverse ecological strategies in these ecosystems, which include a continuum from deciduous species with low-density wood, thick bark, and wide vessels to evergreen species with high-density wood, thin bark, and narrow vessels. The very high FD of TDFs represents a challenge to restoring the likely widest trait ranges of any habitat on earth. Understanding this diversity is essential for monitoring successional changes in minimal intervention restoration and guiding species selection for resilient restoration plantings in the context of climate change.

Pronounced increases in nitrogen emissions and deposition due to the historic 2020 wildfires in the western U.S.

Wildfire outbreaks can lead to extreme biomass burning (BB) emissions of both oxidized (e.g., nitrogen oxides; NOx = NO+NO2) and reduced form (e.g., ammonia; NH3) nitrogen (N) compounds. High N emissions are major concerns for air quality, atmospheric deposition, and consequential human and ecosystem health impacts. In this study, we use both satellite-based observations and modeling results to quantify the contribution of BB to the total emissions, and approximate the impact on total N deposition in the western U.S. Our results show that during the 2020 wildfire season of August–October, BB contributes significantly to the total emissions, with a satellite-derived fraction of NH3 to the total reactive N emissions (median ~ 40%) in the range of aircraft observations. During the peak of the western August Complex Fires in September, BB contributed to ~55% (for the contiguous U.S.) and ~ 83% (for the western U.S.) of the monthly total NOx and NH3 emissions. Overall, there is good model performance of the George Mason University-Wildfire Forecasting System (GMU-WFS) used in this work. The extreme BB emissions lead to significant contributions to the total N deposition for different ecosystems in California, with an average August – October 2020 relative increase of ~78% (from 7.1 to 12.6 kg ha−1 year−1) in deposition rate to major vegetation types (mixed forests + grasslands/shrublands/savanna) compared to the GMU-WFS simulations without BB emissions. For mixed forest types only, the average N deposition rate increases (from 6.2 to 16.9 kg ha−1 year−1) are even larger at ~173%. Such large N deposition due to extreme BB emissions are much (~6-12 times) larger than low-end critical load thresholds for major vegetation types (e.g., forests at 1.5-3 kg ha−1 year−1), and thus may result in adverse N deposition effects across larger areas of lichen communities found in California's mixed conifer forests.

Diverse chronic responses of vegetation aboveground net primary productivity to climatic changes on Three-River Headwaters region

The ecological responses of vegetation to climatic variables along a spatial gradient can be used as guidelines for chronic ecosystem response predictions under global climate change. The chronic responses of aboveground net primary productivity (ANPP) to climatic factors on the Three-river Headwaters (TRH) region were assessed for major vegetation types at the herbage developmental stages using the geographical detectors model, the Normalized Difference Vegetation Index from remote sensing images, and precipitation and air temperature datasets from 2000 to 2019. The results indicated that precipitation was the dominant driver for alpine meadows and steppes, while the impact of temperature on alpine steppes was more evident than that in alpine meadows, and alpine shrubs were more responsive to warming changes. This was possibly because shallower root systems and larger plant leaf area promote the responses of ANPP to precipitation for alpine meadows and steppes, and dormant buds higher from the ground facilitate the impacts of temperature for alpine shrubs. Grasslands also demonstrated differentiated responses to climatic factors at different developmental stages. Precipitation during the previous withering (September–October), pre-growing season (March–April), and vegetative growth (May–June) stages were more influential for ANPP variations. In contrast, ANPP during the reproductive period from July to August exhibited a weaker response to climatic controls. This was possibly attributed to the bud bank replenishment in fall and spring, the largest biomass growth rates in vegetative growth stage, and the non-structural carbohydrates transferred from roots in reproductive stage for perennial herbaceous plants. An elevated temperature, combined with no significant change in precipitation on the TRH may lead to a decrease in ANPP in alpine meadows but alpine shrub expansion, resulting in a reduced supply of palatable forage sources and bringing challenges to grassland management.

Characterising the Land Surface Phenology of Middle Eastern Countries Using Moderate Resolution Landsat Data

Global change impacts including climate change, increased CO2 and nitrogen deposition can be determined through a more precise characterisation of Land Surface Phenology (LSP) parameters. In addition, accurate estimation of LSP dates is being increasingly used in applications such as mapping vegetation types, yield forecasting, and irrigation management. However, there has not been any attempt to characterise Middle East vegetation phenology at the fine spatial resolution appropriate for such applications. Remote-sensing based approaches have proved to be a useful tool in such regions since access is restricted in some areas due to security issues and their inter-annual vegetation phenology parameters vary considerably because of high uncertainty in rainfall. This study aims to establish for the first time a comprehensive characterisation of the vegetation phenological characteristics of the major vegetation types in the Middle East at a fine spatial resolution of 30 m using Landsat Normalized Difference Vegetation Index (NDVI) time series data over a temporal range of 20 years (2000–2020). Overall, a progressive pattern in phenophases was observed from low to high latitude. The earliest start of the season was concentrated in the central and east of the region associated mainly with grassland and cultivated land, while the significantly delayed end of the season was mainly distributed in northern Turkey and Iran corresponding to the forest, resulting in the prolonged length of the season in the study area. There was a significant positive correlation between LSP parameters and latitude, which indicates a delay in the start of the season of 4.83 days (R2 = 0.86, p < 0.001) and a delay in the end of the season of 6.54 days (R2 = 0.83, p < 0.001) per degree of latitude increase. In addition, we have discussed the advantages of fine resolution LSP parameters over the available coarse datasets and showed how such outputs can improve many applications in the region. This study shows the potential of Landsat data to quantify the LSP of major land cover types in heterogeneous landscapes of the Middle East which enhances our understanding of the spatial-temporal dynamics of vegetation dynamics in arid and semi-arid settings in the world.

Spatio-Temporal Assessment of Thunderstorms’ Effects on Wildfire in Australia in 2017–2020 Using Data from the ISS LIS and MODIS Space-Based Observations

The impact of thunderstorms on the wildfire situation in Australia in 2017–2020 was investigated using data from the ISS LIS and MODIS space-based observations. To determine lightning-caused wildfires, a Geographic Information System (GIS) method was carried out, which consisted of a combined investigation of the spatial and temporal distributions of strikes and ignition hotspots. The seasonal variability of thunderstorms and wildfire activity was analyzed. It was established that the maximum seasonal distribution of thunderstorm activity does not coincide with wildfire activity. The interannual changes in strikes were recorded, but this was not revealed for the major vegetation types. Of 120,829 flashes, recorded by the ISS LIS sensor, only 23 flashes could be characterized as lightning-caused wildfire events, i.e., the frequency of lightning ignition was equal to 0.00023 fires/stroke. The lightning ignitions usually took place along the boundary of a thunderstorm, in semiarid areas covered by open scrublands. During the dry Australian period (April–September), very few lightning events were detected by the ISS LIS sensor, while fire activity was quite high. Additionally, it was concluded that the impact of thunderstorms on the fire situation is too small to explain the numerous wildfires during the wet period.

Temporal and Spatial Patterns of Biomass Burning Fire Counts and Carbon Emissions in the Beijing–Tianjin–Hebei (BTH) Region during 2003–2020 Based on GFED4

Biomass burning (BB) plays an important role in the formation of heavy pollution events during harvest seasons in the Beijing–Tianjin–Hebei (BTH) region by releasing trace gases and particulate matter into the atmosphere. A better understanding of spatial-temporal variations of BB in BTH is required to assess its impacts on air quality, especially on heavy haze pollution. The fourth version of the Global Fire Emissions Database (GFED4)’s fire counts and carbon emissions data were used in this research, which shows the varying number of fire counts in China from 2003 to 2020 demonstrated a fluctuating but generally rising trend, with a peak in 2013. Most fire counts were concentrated in three key periods: March (11%), June–July (33%), and October (9.68%). The increase in fire counts will inevitably lead to the growth of carbon emissions. The four major vegetation types of the fires were agriculture (58.1%), followed by grassland (35.5%), and forest (4.1%), with the fewest in peat. In addition, a separate study for the year 2020 found that the fire counts and carbon emissions were different for this year, with the overall average trend in the study time. For example, the monthly peak fire counts changed from June to March. The cumulative emissions of carbon, CO, CO2, CH4, dry matter, and particulate matter from BB in BTH reached 201 Gg, 39 Gg, 670 Gg, 2 Gg, 417 Gg, and 3 Gg in 2020, respectively.

Bermudagrass Cultivars with Different Tolerance to Nematode Damage Are Characterized by Distinct Fungal but Similar Bacterial and Archaeal Microbiomes.

Turfgrass landscapes have expanded rapidly in recent decades and are a major vegetation type in urbanizing ecosystems. While turfgrass areas provide numerous ecosystem services in urban environments, ecological side effects from intensive management are raising concerns regarding their sustainability. One potentially promising approach to ameliorate the ecological impact and decrease the use of agricultural chemicals is to take advantage of naturally evolved turfgrass-associated microbes by harnessing beneficial services provided by microbiomes. Unfortunately, especially compared to agricultural crops, the microbiomes of turfgrasses are not well understood. Here, we analyzed microbial communities inhabiting the leaf and root endospheres as well as soil in two bermudagrass cultivars, ‘Latitude 36’ and ‘TifTuf’, which exhibit distinct tolerance to nematode damage, with the goal of identifying potential differences in the microbiomes that might explain their distinct phenotype. We used 16S rRNA gene V4 and ITS2 amplicon sequencing to characterize the microbiomes in combination with microbial cultivation efforts to identify potentially beneficial endophytic fungi and bacteria. Our results show that Latitude 36 and TifTuf showed markedly different fungal microbiomes, each harboring unique taxa from Ascomycota and Glomeromycota, respectively. In contrast, less difference was observed from bacterial and archaeal microbiomes, which were dominated by Bacteroidetes and Thaumarchaeota, respectively. The TifTuf microbiomes exhibited lower microbial diversity compared to Latitude 36. Many sequences could not be classified to a higher taxonomic resolution, indicating a relatively high abundance of hitherto undescribed microorganisms. Our results provide new insights into the structure and composition of turfgrass microbiomes but also raise important questions regarding the functional attributes of key taxa.

Hidden Diversity-A New Speciose Gall Midge Genus (Diptera: Cecidomyiidae) Associated with Succulent Aizoaceae in South Africa.

Simple SummarySucculent Aizoaceae (often called “mesembs” or ice plants) form a dominant component of the Succulent Karoo in southern Africa, constituting one of the most species-rich families within the Greater Cape Floristic Region (GCFR). Despite the diversity and abundance of these plants, the diversity of insects specialized on them has never been surveyed methodically prior to this study. In a three-year study of the galling insects associated with succulent Aizoaceae in South Africa, we found that they support a rich community of gall midges (Diptera: Cecidomyiidae), virtually all of which are new to science. This is not surprising, given that knowledge of the Afrotropical fauna of gall midges is scarce, with most species described in the 1900s. Here, we describe the new genus Ruschiola with ten species from succulent Aizoaceae in Namaqualand, the Knersvlakte and the Cedarberg regions of South Africa based on morphological, molecular and life history data. The genetic data were particularly important in this study for differentiating taxa, given that Ruschiola species are very similar morphologically. Members of this genus develop in leaf galls or in plant tissues without visible gall formation, and are highly host specific.Aizoaceae (Caryophyllales) constitute one of the major floral components of the unique Greater Cape Floristic Region (GCFR), with more than 1700 species and 70% endemism. Within succulent Aizoaceae, the subfamily Ruschioideae is the most speciose and rapidly diversifying clade, offering potential niches for the diversification of specialized herbivorous insects. Nevertheless, insect diversity on these plants has not been studied to date, and knowledge of gall-inducing insects in the Afrotropics is generally scarce. Our recent observations indicate that succulent Aizoaceae in the GCFR support a rich and largely unstudied community of gall midges (Diptera: Cecidomyiidae). Here, we provide a first report of their diversity with a description of a new genus, Ruschiola Dorchin, and ten new species, based on morphological and molecular analyses of material collected during a three-year targeted survey across major GCFR vegetation types. A high degree of morphological uniformity in Ruschiola suggests recent diversification and necessitated the use of molecular data and laboratory rearing from host plants to verify species boundaries and host ranges.

Flora, vegetation and climate assessment of the Early/Middle Miocene Parschlug flora indicates a distinctly seasonal climate

The late Early/early Middle Miocene flora from Parschlug (Styria, Austria) is famous for its numerous specimens and high diversity. Some taxa previously described are revised here and 42 new angiosperm leaf morphotypes/taxa are described. The Climate Leaf Analysis Multivariate Program (CLAMP) is applied to assess the palaeoclimate. An update of the tool to assess the most suitable modern climate CLAMP calibration dataset is introduced. The Integrated Plant Record (IPR) vegetation analysis, assessing the most likely major vegetation type represented by a fossil flora, and similarity approaches Drudges 1 and 2, indicating the most similar modern vegetation proxies, had been previously applied to data from Parschlug. Both are again applied here on the enlarged floristic spectrum. The results indicate “sclerophyllous subhumid forest” as the most likely major zonal vegetation type for Parschlug and European vegetation, namely “Thermophilous mixed deciduous broadleaved forests”, distributed today in southern and southeastern Europe, as the most similar modern vegetation. The climate for Parschlug, inferred from CLAMP and the climate in the region of the modern vegetation proxies, indicates distinct seasonality in precipitation and temperature.

Floral Diversity Status in Urban Coastal Wetland & Associated Coastal Ecosystems of Crow Island Mattakkuliya, Sri Lanka

Colombo is the capital of Sri Lanka and the only wetland city in South Asia under the Ramsar Convention. Crow Island Beach Park and associated coastal area belong to the Colombo urban coastal wetland ecosystems. Crow Island wetland contributes diverse habitats for numerous flora and fauna species. The present study was conducted to assess the status of floral diversity in the Crow Island Beach Park and associated coastal ecosystem during the months of August to October 2021. Study area is divided in to three sites (A, B, C). Line transects method and field observations were used in the study. This coastal wetland consists of mosaic of five major vegetation types: Herbaceous, tree, shrub, creeper, grass and other than that marine algae namely Chaetomorpha antennina, Rhizoclonium africanum, Ulva compressa belonging to chlorophyta (green algae) and Grateloupia lithophila belonging to rhodophyta (red algae) were found in the study area. A total number of 102 flora species belonging to 50 families were recorded from the study area. There were two true mangrove species and 16 mangrove associated species in the study sites. Out of the 102 plant species 46 were recognized and documented as plants with medicinal values. Shannon-Wiener diversity indexes for mangrove and mangrove associated species were recorded as 2.378, 2.304 and 1.676 in site A, B and C respectively. Simpson’s diversity index for mangrove and mangrove associated species was recorded as 0.889, 0.874 and 0.735 respectively in site A, B and C and Jaccard index of similarity between three study sites showed high values ranging from 41% to 69% for mangrove and mangrove associated species.

Characterising Dutch forests, wetlands and cultivated lands on the basis of phytolith assemblages

Abstract Palaeoecological reconstructions in the Netherlands are commonly based on pollen and macrofossil analysis, but can be limited if the preservation of organic material is poor. Phytoliths, biogenic silica, do not have this limitation and preserve in settings where other macro- and microfossils do not. Little is known about how phytolith assemblages preserved in soils and sediments reflect the parent vegetation in north-western European systems, so it is currently difficult to contextualise past environments. Here, we characterise phytolith assemblages for soil samples recovered from three major vegetation types in the Netherlands to provide reference data for future reconstructions of past vegetation change. We collected 42 soil surface samples from forests, wetlands and agricultural fields across the Netherlands and characterised the phytolith assemblages they contained. We identified the different phytolith morphotypes and quantified the percentages and concentrations (#phytoliths/cm3 soil) in each sample. We used non-metric multidimensional scaling to assess the variation in phytolith assemblage composition within, and between, the three vegetation types. The phytolith assemblages analysed from the forests, wetlands and agricultural fields were clearly distinguishable from each other. Agricultural fields were dominated by four phytolith morphotypes of grass silica short cells (GSSCs): rondel (tabular), cross type 1 (>15 µm), rondel (elongated) and disturbance or crop phytoliths. Forests settings had significantly higher amounts of different arboreal phytoliths (large and small spheroid rugose) compared with other vegetation types. Wetlands could be identified by significantly higher amounts of Cyperaceae phytoliths (papillate) and other GSSCs (saddle and bilobates with thick castula). Phytolith assemblages could distinguish different subtypes of vegetation within forest and wetland areas, while differences between agricultural systems could not be identified. Our study demonstrates that phytoliths preserved in soils or sediments can be used to separate major vegetation types across the Netherlands. Thus, these results support the hypothesis that phytoliths can be used to infer past environmental conditions in palaeoecological reconstructions. We suggest that future work should: (1) focus on characterising which phytolith types are produced by the commonest tree, wetland, shrub and herb species in the Netherlands and (2) characterise phytolith assemblages across a wider array of vegetation types in north-western European systems to increase the capability for quantitative reconstructions using phytolith assemblages.

Stocking density and distribution in relation to vegetation in a biodiverse semi-arid pastoral system in South Africa

The spatial heterogeneity of vegetation in a communal grazing system provides pastoralists with a range of grazing sites to select for their livestock. When fencing spatially constrains herds, there is reduced access to ecological heterogeneity, which may have a negative impact on livestock and the grazing resource. This study investigated temporal and spatial changes in stocking densities and distribution within the six major vegetation types of the Leliefontein pastoral area in Namaqualand, South Africa. This semi-arid, biodiverse area of about 2000 km2 supports a spatially-constrained mobile pastoral system based on small stock production. Over the data period from 1999 to 2006, the location of 256 small stock herds, their temporal occupancy and herd size were used to determine stocking densities within the daily grazing radius of herds. These grazing radii were overlaid using GIS to produce stocking density distributions over the landscape. The density and location of herds were unevenly distributed when assessed monthly and annually. Parts of the study area were consistently overstocked whereas others remained ungrazed. We argue that the recommendation of fixed stocking rates within this variable environment is inappropriate because forage availability and quality fluctuate within and between years and within drought cycles. We conclude that development interventions should rather focus on reducing stocking densities during and after drought periods. This would benefit pastoralists through reduced livestock mortalities and the vegetation would recover more quickly from the impacts of drought.

Forest Vegetation Cover in Yok Don National Park, Vietnam

Yok Don National Park is located in the tropical rainforest zone on the Central Highlands of Vietnam. The obtained results from the study undertaken on the composition of plant species and forest vegetation in National Park indicated a record of 856 species, 473 genera and 129 families that belongs to the four divisions of vascular plants. These includes: Lycopodiophyta, Polypodiophyta, Pinophyta and Magnoliophyta. Useful plants of 856 taxonomy species listed consists of 498 species of medicinal plants, 157 species of timber plants, 144 species of edible plants, 60 species of ornamental plants, 19 species of industrial plants, 10 species of fiber plants and 38 species of unknown use plants, respectively. During the duration of investigation, Peliosanthes teta Andrews was newly recorded in the forest vegetation of National Park. A variety of forest vegetations in the area under study is described. In this study, four major vegetation types of forest were identified in Yok Don National Park.

Reproduction and genetic diversity of Juniperus squamata along an elevational gradient in the Hengduan Mountains

Elevation plays a crucial factor in the distribution of plants, as environmental conditions become increasingly harsh at higher elevations. Previous studies have mainly focused on the effects of large-scale elevational gradients on plants, with little attention on the impact of smaller-scale gradients. In this study we used 14 microsatellite loci to survey the genetic structure of 332 Juniperus squamata plants along elevation gradient from two sites in the Hengduan Mountains. We found that the genetic structure (single, clonal, mosaic) of J. squamata shrubs is affected by differences in elevational gradients of only 150 m. Shrubs in the mid–elevation plots rarely have a clonal or mosaic structure compared to shrubs in lower- or higher–elevation plots. Human activity can significantly affect genetic structure, as well as reproductive strategy and genetic diversity. Sub-populations at mid-elevations had the highest yield of seed cones, lower levels of asexual reproduction and higher levels of genetic diversity. This may be due to the trade-off between elevational stress and anthropogenic disturbance at mid-elevation since there is greater elevational stress at higher-elevations and greater intensity of anthropogenic disturbance at lower-elevations. Our findings provide new insights into the finer scale genetic structure of alpine shrubs, which may improve the conservation and management of shrublands, a major vegetation type on the Hengduan Mountains and the Qinghai-Tibet Plateau.

Tree Species Classification Based on Sentinel-2 Imagery and Random Forest Classifier in the Eastern Regions of the Qilian Mountains

Obtaining accurate forest coverage of tree species is an important basis for the rational use and protection of existing forest resources. However, most current studies have mainly focused on broad tree classification, such as coniferous vs. broadleaf tree species, and a refined tree classification with tree species information is urgently needed. Although airborne LiDAR data or unmanned aerial vehicle (UAV) images can be used to acquire tree information even at the single tree level, this method will encounter great difficulties when applied to a large area. Therefore, this study takes the eastern regions of the Qilian Mountains as an example to explore the possibility of tree species classification with satellite-derived images. We used Sentinel-2 images to classify the study area’s major vegetation types, particularly four tree species, i.e., Sabina przewalskii (S.P.), Picea crassifolia (P.C.), Betula spp. (Betula), and Populus spp. (Populus). In addition to the spectral features, we also considered terrain and texture features in this classification. The results show that adding texture features can significantly increase the separation between tree species. The final classification result of all categories achieved an accuracy of 86.49% and a Kappa coefficient of 0.83. For trees, the classification accuracy was 90.31%, and their producer’s accuracy (PA) and user’s (UA) were all higher than 84.97%. We found that altitude, slope, and aspect all affected the spatial distribution of these four tree species in our study area. This study confirms the potential of Sentinel-2 images for the fine classification of tree species. Moreover, this can help monitor ecosystem biological diversity and provide references for inventory estimation.

Assessing changes in flora distribution of Akoka forest ecosystem, 52 years after urban encroachment using field surveys and integrated remote sensing data.

The numerous benefits and the need to conserve urban forest is increasingly been acknowledged by scientists, land managers as well as decision makers. However, unlike the developed regions of the world, urban forest composition and structure in developing countries such as Nigeria remains the most threatened and least-studied. Using intensive field surveys and remote sensing data, this study investigated changes in species composition and structure of nine vegetation types in Akoka between 1962 and 2014. Field data on individual species was collected along a belt transect laid across the nine vegetation boundaries. Species composition, richness and diversity differed among the vegetation types as well as between 1962 and 2014. Species composition ranged from 3 to 19 across the vegetation types and was highest in fresh water swamp forest. While brackish marsh land had highest total number of individual, fresh water swamp forest located near the parks and garden had the least likely due to its nearness to ceaseless human disturbance. The species diversity was generally low across the vegetation types, and varied between 1.32 in brackish marsh land to 2.63 in mangrove swamp forest. The overall initial vegetation of Akoka had significantly fragmented and diminished between 1962 and 2014. Compared to 1962, the percentage vegetation cover by the major vegetation types had reduced, indicating that while anthropogenic disturbance persisted, little or no effort was put in place to improve their restoration. Overall, our findings pointed to the needs for sustainable management of urban forest with keen attention being paid to restoration.