Forest Fire Regimes and Plant Diversity in Tropical Dry Deciduous Forests of Central India

Initial conditions influence effects of prescribed burns and deer exclosure fences on tree regeneration and understory diversity in Appalachian oak-dominated forests

We analysed the relative role of landscape context (city, suburb and exurb) and distance to the edge (from forest edge to 45 m in interior) on plant diversity of natural forests in Wuhan city. The results indicated that landscape context had significant effects on plant diversity, and both landscape context and distance to the edge affect vegetation and disturbance characteristics. Landscape context was the main factor affecting richness of woods, herbs, indigenous species, forest generalists and insect or wind pollination species. These species tended to be higher in exurban forests while non-indigenous species were higher in the urban forests. The number of non-indigenous species, forest specialists, herbs and insect pollination species also depended on distance to the edge or on both interactions. Richness of non-indigenous species decreased with increasing distance to the edge in urban forest. Vegetation characteristics that shrub cover was lower and disturbance characteristics that disturbed cover and human activity were higher in the urban edge than in the suburb and exurb edge, which decreased from the edge to the interior. Therefore, we should prioritize the preservation of less disturbed and frequented forests (suburban and exurban) to buffer the invasion of non-indigenous species, and to reserve more indigenous species.

Abiotic factors are important to shape plant community composition and diversity through processes described as environmental filtering. Most studies on plant diversity in forests focus on adult trees, while the abiotic drivers of forest seedling community characteristics are less understood. Here, we studied seedling banks’ composition, richness, diversity, and abundance, and investigated their relationships with microsite abiotic conditions along a wide elevational gradient. We sampled seedling communities in 312 1-m2 quadrats, distributed in 13 one-ha plots in four subtropical forests in south China, covering an elevation gradient of 1500 m, for 2 years. We measured light availability, slope, and 11 soil nutrients for each seedling quadrat. We used analysis of similarities and multivariate analysis of variance to compare the composition and abiotic drivers of the four forests’ seedling communities. We then used mixed models and structural equation modeling to test the direct and indirect effects of abiotic factors on seedling species richness, diversity, and abundance. The differences in seedling community composition among these forests were mostly explained by differences in elevations and soil nutrients. Seedling diversity as Shannon and Simpson diversity index decreased with increasing elevation and increased with increasing slope, but seedling abundance and species richness did not. Elevation had an indirect effect on Simpson’s diversity index through modulating the direct effects of soil properties. Our findings show that soil properties play a prominent role in favoring differentiation in species composition among the four forests we studied and provide additional evidence to decreasing species diversity with elevation. However, this was reflected in decreasing Shannon and Simpson indices rather than species richness, which is more commonly studied. Whether and to what extent future environmental changes in climate and soil acidification will alter future forest composition and diversity needs to be investigated.

Diversity, above-ground biomass, and vegetation patterns in a tropical dry forest in Kimbi-Fungom National Park, Cameroon

Abstract. Mwaluseke ML, Mwakalukwa EE, Maliondo SMS. 2023. Vegetation composition, diversity, stand structure and carbon stock of a dry evergreen montane forest of Lendikinya forest reserve in Tanzania. Biodiversitas 24: 551-562. There is limited information on woody plant diversity and vegetation patterns in African dry forests, particularly in East Africa, and hence increasing the interests in understanding species composition, diversity, and structural attributes of catchment forest reserves found in Tanzania. Moreover, tree species composition, species richness, and carbon stock are not well documented in most montane forests in the region, apart from Ethiopia. Their potential in terms of carbon storage is also important for understanding their productivity and the extent to which they can be used in mitigating the effects of climate change. This study assessed vegetation composition and diversity, stand structure and potential carbon stocks of Lendikinya Forest Reserve, a dry evergreen montane forest located in Monduli District in Tanzania. A total of 56 concentric circular plots with subplots of 2 m, 5 m, 10 m, 15 m and 20 m radii were used to collect woody species data on standing trees and stumps across the entire forest of 3,689 ha. A total of 79 species belonging to 36 families were identified. Drypetes natalensis (9.2%), Diospyros abyssinica (7.1%) and Dombeya rotundifolia (6.5%) were the most important species as per the Importance Value Index (IVI). The diversity indices have indicated the forest reserve to have a high diversity of woody species. Stand structure comprises 1,398 ± 679 stems ha-1, basal area of 11.42 ± 5.41 m2ha-1and standing volume of 54.47 ± 24.1 m3ha-1 while the mean carbon stocks were 16.04 ± 7.7 t C ha-1. The alarming disturbances stress the urgent need for increased conservation efforts in order to protect the existing biodiversity and increase carbon storage and enhance water conservation in the reserve.

A landscape level plant diversity and population inventory was made in northern portion of eastern Ghat region of India comprising mostly dry deciduous and moist deciduous forests. A total of 444 transects of 0.5 ha (5 × 1000 m) area each was used for enumerating trees. Diversity and density of herbs, shrubs, lianas and regeneration of tree species were assessed from 5 x 5 m size plots within transects. A total of 882 species belonging to 532 genera and 129 families were recorded comprising of 263 tree species, 78 species of shrubs, 138 species of climbers/twinners and 403 species of herbs. Shorea robusta, Lannea coromandelica, Madhuca india and Diospyros melanoxylon were the predominant tree species where members of Euphorbiaceae, Rubiaceae, Fabaceae and Combretaceae contributed to maximum species richness, stand density and basal area. The stand density ranged from 268 to 655 stems ha−1 while basal area varied from 6.65 to 22. 28 m2 ha−1. The tree density and species richness decreased with increasing girth class; highest number of species and maximum density was recorded for 30 to 60 cm girth class. Shannon-Weiner Index and Simpson Index varied in the range of 1.85-2.05 and 0.013-0.018, respectively. Regeneration of many tree species was observed to be poor. Key words: Plant diversity, population structure, Eastern Ghat, India.

Forest fire is a common phenomenon in tropical forest likes in Indonesia. Beside the effect of soaring heat and lack of rain during dry season due to the tropical climate, farming system is also reported as one reason of forest fire in Indonesia. People of surrounding areas and neighbouring countries are suffering from the effect of forest fire. Plants and animals are the most suffer from this occurrence that they cannot escape. This study aimed to investigate the effect of previously burnt and un-burnt tropical forest in Borneo Island on the plant and insect diversity of the tropical forest. The result of the study found that the plants in previously burnt forest area was dominated by one species, while higher and more stable plant diversity was found in un-burnt forest. Although the number of individual insects was higher in previously burnt tropical forest, but the insects was more diverse in un-burnt tropical forest. The alteration of environmental conditions in previously burnt and un-burnt forest indicate that the energy held in natural forest support higher number and more stable insects than previously burnt forest.

Growing emphasis on sustainability has increased the demand for information on effects of forest management on species diversity. We investigated the hypothesis that plant diversity is a function of microsite heterogeneity by documenting plant diversity and heterogeneity in canopy cover, light, and soil moisture produced by four silvicultural treatments during the first growing season following treatment: prescribed burning, wildlife retention cut with prescribed burning, wildlife retention cut, and shelterwood cutting. Treatments and controls were randomly assigned within four relatively undisturbed, 70–90-year-old oak-hickory stands. Heterogeneity in canopy cover and photosynthetically active radiation was greatest after shelterwood cutting, whereas the wildlife retention cut resulted in less removal of canopy trees and a smaller increase in heterogeneity of these factors. The addition of prescribed burning enhanced the effects of the wildlife retention cut. Prescribed burning alone had the least impact on heterogeneity of these factors. Soil moisture variability appeared to be independent of treatments. Shelterwood cutting increased first-year herbaceous plant diversity, and this increase was likely due, in part, to increased heterogeneity in canopy cover, light, and seedbed condition. These first-year results partially support the hypothesis that plant diversity is a function of microsite diversity in these forests. Long-term monitoring is underway.

Research on understory plant diversity and its response to environmental factors helps in the sustainable development of plantation forests. We investigated the characteristics of understory plant diversity in Eucalyptus plantation forests located in Dongfang, Ding'an, Tunchang, and Lingao on Hainan Island by leveraging the plot survey method, and analyzing how the understory plant diversity in these Eucalyptus plantation forests responds to environmental factors. The results showed that a total of 124 plant species belonging to 62 families and 112 genera were recorded in the sampled plots of the Dongfang, Ding’an, Tunchang, and Lingao regional sites on Hainan Island, among which species of Fabaceae and Poaceae comprised the largest number of plants. The number of species and plant diversity indices of the shrub layer and herb layer in Eucalyptus plantation forests varied at different sites, The richest understory vegetation in Tunchang, located in the center of Hainan Island, and the highest α-diversity whether gauged by species or phylogenetically. The similarity of the understory plant community species was greatest between Ding’an and Tunchang, whereas the difference in composition was largest between Dongfang and the other three sites. Phylogenetically, the understory plant community at Ding’an had the most distant affinities among species, whereas that at Tunchang had the closest affinities among species. The results of the Mantel test and redundancy analysis revealed differing correlations between plant diversity in the shrub layer versus herb layer and various environmental factors. In particular, elevation and annual average temperature are the two main factors influencing plant diversity in the shrub layer, and soil available nitrogen and annual average sunshine duration are the two main factors influencing plant diversity in the herb layer. Variance decomposition showed that the combined effect of soil, climate, and topography factors is the main driver shaping plant diversity in the shrub layer of the understory in Eucalyptus plantation forests, while the combined effect of climate and soil factors is the main one determining plant diversity in their herb layer.

Context The spectral variation hypothesis (SVH) suggests that remotely sensed spectral variation correlates with biodiversity. However, conflicting evidence has been presented regarding the SVH, it has not been widely tested in high-latitude landscapes, and its assessments mainly employ species richness, omitting other aspects of biodiversity. Objectives We examine plant diversity, spectral variation and the SVH across a northern boreal landscape utilizing high-spatial-resolution satellite imagery. We incorporate taxonomic, phylogenetic, functional, and indicator-based plant diversity metrics and visualize spatial differences between proposed plant diversity proxies. Methods We surveyed plant community composition in peatlands, forests, and tundra in northwest Finland and calculated 14 diversity metrics for 355 sites. We compared observed diversity with (1) spatial, (2) temporal, (3) multivariate spatiotemporal spectral variation, and (4) multivariate machine learning. We used statistical relationships and machine learning models to create continuous maps of plant diversity. Results While forests were generally more biodiverse than peatlands or tundra, each of these ecosystems obtained the highest values in some metrics. Spectral variation had positive correlations (0.14–0.72) across most dimensions of plant diversity, but relationships varied between ecosystems and were sometimes insignificant or negative. For example, plant diversity in forests was largely uncorrelated with spatial spectral variation. Temporal spectral variation was more strongly correlated with plant diversity than spatial spectral variation in a majority (41 of 56) of cases. Conclusions While spectral variation was usually correlated with plant diversity, correlations varied among peatlands, forests, and tundra. Thus, methods for estimating plant diversity should be tailored to different biodiversity metrics and ecosystem types.

Forest fires can alter essential ecosystem processes, including soil nutrient cycling, potentially cascading into permanent vegetation changes. This is key to elucidate in ecosystems where fires are infrequent. We assessed the effects of fire severity on the spatio-temporal response of soil nutrients and plant diversity in old-growth forests of south-central Chile, 1, 2, and 3 years after a fire that occurred in 2015. Within ancient, old-growth Araucaria araucana (Mol.) K. Koch and Nothofagus pumilio (Poepp. and Endl.) Krasser forests, ranging from areas burned with fire of high severity to unburned forests, we evaluated nitrogen (N), phosphorus (P), potassium (K), and soil organic matter (SOM) content using spatial interpolation to predict their spatial distribution and assessed their availability over time. We also assessed plant species richness and abundance following the fire. The availability of N noticeably increased during the first year after fire but rapidly decreased in the following years, especially in areas of high fire severity. P, K, and SOM were less affected by the fire, remaining more constant over time. In the short term, plant species richness and diversity significantly decreased in severely burned areas, but over time, they became more similar to those of the unburned forests. The time since a fire and its severity determine a heterogeneous distribution of soil nutrients, with N shifting to a significantly lower availability after fire, which was more notable in areas of high fire severity. Here, vegetation exhibited a decrease in plant diversity and the establishment of exotic species, likely producing cascading effects at the community level.

Vascular plant and cryptogam diversity in Fagus sylvatica primeval forests and comparison to production stands in the western Carpathian Mountains, Slovakia

A study was conducted to analyze the tree species composition and diversity in the Central Indian dry deciduous forest of Nauradehi Wildlife Sanctuary, Madhya Pradesh. The objective of the current study was to understand the impact of forest fire on the tree species diversity in the Central Indian tropical dry deciduous forest. Identification of fire-affected areas was done based on satellite remote sensing data of Landsat 5,7 and 8 satellite images, and different fire zones were classified in the study area into five fire frequency classes i.e., F1 to F4 and one unburned class i.e., F0. Five plots were laid within each fire class including the unburned class. A total of 3128 trees belonging to 49 plant species, 39 genera, and 14 families were recorded in all the fire frequency classes. Tectona grandis is the dominant tree species in the unburned, low fire, moderate fire, and in high fire zones where Terminalia tomentosa dominated in the severe burn areas. The results show that with the increased in fire frequency the tree species diversity, basal area and IVI increased from low, medium and high fire zones. However, these parameters decreased and again increased in the severe fire zones. The results of different indices indicate that tree diversity fluctuates with the increase in fire frequency.

Abiotic factors are important to shape plant community composition and diversity through processes described as environmental filtering. Most studies on plant diversity in forests focus on adult trees, while the abiotic drivers of forest seedling community characteristics are less understood. Here, we studied seedling banks’ composition, richness, diversity, and abundance, and investigated their relationships with microsite abiotic conditions along a wide elevational gradient. We sampled seedling communities in 312 1-m2 quadrats, distributed in 13 one-ha plots in four subtropical forests in south China, covering an elevation gradient of 1500 meters, for two years. We measured light availability, slope, and 11 soil nutrients for each seedling quadrat. We used analysis of similarities and multivariate analysis of variance to compare the composition and abiotic drivers of the four forests’ seedling communities. We then used mixed models and structural equation modeling to test the direct and indirect effects of abiotic factors on seedling species richness, diversity, and abundance. The differences in seedling community composition among these forests were mostly explained by differences in elevations and soil nutrients. Seedling diversity as Shannon and Simpson diversity index decreased with increasing elevation and increased with increasing slope, but seedling abundance and species richness did not. Elevation had an indirect effect on Simpson’s diversity index through modulating the direct effects of soil properties. Our findings show that soil properties play a prominent role in favoring differentiation in species composition among the four forests we studied and provide additional evidence to decreasing species diversity with elevation. However, this was reflected in decreasing Shannon and Simpson indices rather than species richness, which is more commonly studied. Whether and to what extent future environmental changes in climate and soil acidification will alter future forest composition and diversity needs to be investigated.

Tropical deciduous forests provide habitat to a wide range of life forms and ecosystem services to mankind. Forest fires in these forests have become an environmental threat that challenges the vulnerability of ecosystems and communities in the immediate vicinity. These also contest the adaptation and resilience as they act as carbon sinks. However, at times forest fires in these Tropical deciduous forests become disastrous and such disasters are expected to increase with the predicted climate change scenarios. These uncontrolled fires often bring damage to the resources and services being provided by the forests. To curb the variety of damages due to fire, the implementation of fire management strategies and the identification of responsible factors is important for disaster risk reduction. Fire susceptibility mapping and modeling of the area provides a framework for the anticipatory adaptation and solution toward reducing the impact of forest fire disasters. The framework for susceptibility mapping guides monitoring and assessment of species richness, soil and vegetation interaction, and changes in the usage of non-timber forest products by the local communities. Though the distribution of fire susceptibility is highly dependent on the terrain conditions, the accessibility to the forest products is determined by their availability. This paradigm shift of forest dominant landscapes from the fire risk zones to community interactive landscapes would enhance the adaptation frameworks for the less studied disasters and their dynamics in the climate change scenarios.KeywordsForest fireSusceptibility mappingModelingAdaptation