Cascading effects of climate extremes on vertebrate fauna through changes to low‐latitude tree flowering and fruiting phenology

Abstract

Forest vertebrate fauna provide critical services, such as pollination and seed dispersal, which underpin functional and resilient ecosystems. In turn, many of these fauna are dependent on the flowering phenology of the plant species of such ecosystems. The impact of changes in climate, including climate extremes, on the interaction between these fauna and flora has not been identified or elucidated, yet influences on flowering phenology are already evident. These changes are well documented in the mid to high latitudes. However, there is emerging evidence that the flowering phenology, nectar/pollen production, and fruit production of long-lived trees in tropical and subtropical forests are also being impacted by changes in the frequency and severity of climate extremes. Here, we examine the implications of these changes for vertebrate fauna dependent on these resources. We review the literature to establish evidence for links between climate extremes and flowering phenology, elucidating the nature of relationships between different vertebrate taxa and flowering regimes. We combine this information with climate change projections to postulate about the likely impacts on nectar, pollen and fruit resource availability and the consequences for dependent vertebrate fauna. The most recent climate projections show that the frequency and intensity of climate extremes will increase during the 21st century. These changes are likely to significantly alter mass flowering and fruiting events in the tropics and subtropics, which are frequently cued by climate extremes, such as intensive rainfall events or rapid temperature shifts. We find that in these systems the abundance and duration of resource availability for vertebrate fauna is likely to fluctuate, and the time intervals between episodes of high resource availability to increase. The combined impact of these changes has the potential to result in cascading effects on ecosystems through changes in pollinator and seed dispersal ecology, and demands a focused research effort.

Assessing Species Vulnerability to Climate Change in Tropical Asia: Implications for Biodiversity Conservation and Forest Management

“…Niño Southern Oscillation, African Intertropical Convergence Zone) and anthropogenic climate factors (e.g., greenhouse gases, ozone depletion, and deforestation) are the key drivers of variability in climate change and extreme events in the tropics (Butt et al 2015). The Intergovernmental Panel on Climate Change (IPCC) states that several projections indicate that the geographical distribution, species composition, and productivity of tropical forest ecosystems are likely to be significantly impacted by climate change (IPCC 2014).…”

“…In northern India, flowering occurs in canopy trees and understory trees during the dry season and rainy season respectively (Shukla & Ramakrishnan 1982). Fruiting phenology of trees is also likely to be influenced by climate change in tropical deciduous forests (Butt et al 2015;Kushwaha et al 2011). …”

“…In tropical Asia, variation in rainfall intensity, temperatures and evapotranspiration may lead to an increase in the length of periods between mass flowering and fruiting events of tree species (Butt et al 2015). This may impact the tree phenology particularly irregular flowering and fruiting.…”

“…Climate change affects forest ecosystems through changes in mean temperature and rainfall and through changes in the frequency and severity of weather and climate extremes, such as wildfires, severe storms, cyclones, and drought (Butt et al 2015;Garcia et al 2014). These impacts are broadly characterised as changes in: species' distribution (Thuiller et al 2008); forest composition (relative abundance of species); forest structure (Bai et al 2011;Grimm et al 2013); and flowering and fruiting phenology (Butt et al 2015). Rising temperatures increase the frequency and magnitude of extreme events, and changes in seasonality are altering the structure and function of forest ecosystems (Grimm et al 2013).…”

“…Among the biotic components of forests, trees are one of the earliest groups to be affected by climate change, through changes in phenology and distribution, and these changes could have cascading effects on the functioning of forest ecosystems (Butt et al 2015;Cleland et al 2007;Corlett & Lafrankie Jr 1998). Although trees generally respond slowly to climate change, their long life-spans suggest they will be unlikely to adapt fast enough to avoid negative impacts of climate change, such as heat and moisture stress and resulting high mortality rates (Margrove et al 2015;Solomon & Kirilenko 1997).…”