Climate Change Effects, Adaptation, and Mitigation Techniques in Tropical Dry Forests

Tropical dry forests is one of the most unique forest types. It differs from other tropical forests with its climatic behavior like a prominent dry period, little annual rainfall, and high evapotranspiration. Out of six global bioclimatic zones, the forests are distributed in four. Climate change is now the most challenging issue regarding the fate of tropical dry forests. A severe climatic change is estimated to occur between 2040 and 2069 that could drastically change the precipitation pattern, temperature, aridity, and distribution of biodiversity. It could alter the forest type permanently. With a large number of heat-tolerant species, tropical dry forests have a great potentiality to conservationists with the prediction of a large area that could attain the climatic condition favorable for extension of tropical dry forests. But many of the species of tropical dry forests could be extinct due to changing climate at the same time. Proper adaptation and mitigation techniques could minimize the severity of climate change effects.

Effect of Climate Change on Tropical Dry Forests

Around 1.6 billion people in the world are directly dependent on forests for food, fodder, fuel, shelter, and livelihood, out of which 60 million are entirely dependent on forests. Forests silently provide us with ecosystem services such as climate regulation, carbon sequestration, harbouring biodiversity, synchronizing nutrient cycling, and many more. Tropical Dry Forests (TDF's) occupy around 42% of total forest area of the tropics and subtropics and facilitate sustenance of world's marginalized populations. Change in vegetation composition and distribution, deflected succession, carbon sequestration potential, nutrient cycling and symbiotic associations would affect TDF at ecosystem level. At species level, climate change will impact photosynthesis, phenology, physiognomy, seed germination, and temperature-sensitive physiological processes. In order to mitigate the effects of climate change, specific mitigation and adaptation strategies are required for TDF that need to be designed with concerted efforts from scientists, policy makers and local stakeholders.

Aboveground Biomass Stockpile of Trees in Vallanadu Blackbuck Sanctuary, Peninsular India

A forest tree inventory study was conducted in Vallanadu Black buck sanctuary, Tuticorin. The current study was conducted to assess tree density, species richness, basal area (BA) and aboveground biomass (AGB) stockpile. The study area has been classified as Southern Thorn Forest (SFT). One hundred square plots (total area 1 ha), each 10m × 10m (100 m2 each) laid randomly across study area. All live trees with ≥5 cm diameter at breast height (DBH) measured at 137 cm above the ground. As the whole, 1335 individual trees ≥5cm DBH recorded. A total number of 18 species recorded from 14 genera and 11 families in study area. The family Mimosaceae has maximum number of species (7 species) followed by Rhamnaceae (2 species), while 9 families had just single species’ each. The total basal area recorded was 22.046 m2 ha-1, while, the mean wood density (WD) of trees estimated as 0.70±0.093 g cm-3. Total amount of 50.065 Mg ha-1 present in STF. The contribution of different species in terms of total AGB varied significantly. Commiphora berryi stocked 45.13% (22.588 Mg ha-1) of AGB followed by A. planifrons (23.31%, 11.669 Mg ha-1), A. mellifera (7.233%, 3.621 Mg ha-1), whereas remaining 15 species collectively stocked 24.327% (12.187 Mg ha-1) AGB. The STF had a large number of trees compared to some dry forests within Tamil Nadu. Southern Thorn Forest endowed with a moderate number of trees species. Aboveground biomass stockpile of trees is comparable with the range recorded from Indian dry forests. The study area experiences lesser mean annual rainfall and >6 months dry season. Further, endowed with short-bole and smaller leaved trees, hence stocked a relatively lesser AGB in trees.

A new species of Atrypanius Bates, 1864 (Cerambycidae: Lamiinae: Acanthocinini) from Peruvian seasonally dry forests

A new species of the genus Atrypanius Bates, 1864 is described from Peru: Atrypanius unpanus n. sp., based on specimens collected from the campus of the National University of Piura, an important area of seasonally dry forest in the Piura region, northwestern Peru.

Makaya gen. nov. (Hemiptera: Fulgoromorpha: Flatidae) from dry forests in western Madagascar

A new monospecific genus of flatid planthoppers (Hemiptera: Fulgoromorpha: Flatidae), Makaya gen. nov., is described for Makaya volontany sp. nov. (type species) from the island of Madagascar. Habitus, male and female external and internal genital structures of the new species are illustrated and compared with related taxa. Makaya volontany is endemic to Madagascar where it is currently known from different types of dry forests in the western part of the island.

Evaluating critiques of evidence of historically heterogeneous structure and mixed-severity fires across dry-forest landscapes of the western USA

The structure and role of fire in historical dry forests, ponderosa pine (Pinus ponderosa) and dry mixed-conifer forests, of the western USA, have been debated for 25 years, leaving two theories. The first, that these forests were relatively uniform, low in tree density and dominated by low- to moderate-severity fires was recently reviewed, including a critique of opposing evidence. The second, that these forests historically had heterogeneous structure and a mixture of fire severities, has had several published reviews. Here, as authors in part of the second theory, we critically examined evidence in the first theory’s new review, which presented 37 critiques of the second theory. We examined evidence for and against each critique, including evidence presented or omitted. We found that a large body of published evidence against the first theory and supporting the second theory, presented in 10 published rebuttals and 25 other published papers, by us and other scientists, was omitted and not reviewed. We reviewed omitted evidence here. Omitted evidence was extensive, and included direct observations by early scientists, maps in early forest atlases, early newspaper accounts and photographs, early aerial photographs, seven paleo-charcoal reconstructions, ≥18 tree-ring reconstructions, eight land-survey reconstructions, and an analysis of forest-inventory age data. This large body of omitted published research provides compelling evidence supporting the second theory, that historical dry forests were heterogeneous in structure and had a mixture of fire severities, including high-severity fire. The first theory is rejected by this large body of omitted evidence.