Dartmouth in Namibia ENVS 84 Final Reports 2015
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Dartmouth in Namibia Dartmouth College, Environmental Studies Program, Hanover NH USA October-November 2015 Table of Contents !Nara Phenology and Pollination ..................................................................................................2 References ..................................................................................................................................20 Appendix .....................................................................................................................................23 Towards a Comprehensive Environmental Education Program at Gobabeb: Case Study of Grade 7 Curriculum Development for the J.P. Brand School ................................................24 References ..................................................................................................................................46 Appendices ..................................................................................................................................49 Long Term Study of the !Nara Plant Year III: A Continuation and Expansion of Monitoring Methods ....................................................................................................................70 References ..................................................................................................................................87 Appendices .................................................................................................................................90 Vegetation Distribution and Livestock Resource Use in the Lower Kuiseb River ................97 References ................................................................................................................................127 Appendices ...............................................................................................................................129 1 !Nara Phenology and Pollination November 14, 2015 Prepared By: Caitlin Anderson Mary-Katherine Andrews Margaret Rauner Caroline Resor 2 Introduction Successful plant development relies on a carefully orchestrated series of events. Plant phenology, or the timing of events in a plant’s life, is in part determined by environmental variables. There is always a risk that environmental change will destabilize its phenological patterns or those of its pollinators, or even put the life cycles of pollinators and plants out of sync. This phenomenon is known as phenological mismatch, and in extreme cases it can result in the extinction of plants and pollinators (Harrison 2000; Wall et al 2003; Memmott et al 2007). Climate change presents one such extreme case, so it motivates research on phenology (Kearns et al 1998; Biesmeijer et al 2006; Memmott et al 2007). The primary objective of this research is to explore the relationship between a handful of environmental factors and plant phenology – emphasizing pollination – to begin to understand the phenological impacts of climate change. Climate change predictions have been largely focused on rises in global temperature. Increasing mean temperatures are linked to advancement in plant and pollinator phenology. Temperature is one of the main indicators that plants use to determine when to flower. In temperate zones, the average advancement of first flowering and pollinator flight activity was four days per degree Celsius increase in temperature in the 20th century (Memmott et al 2007). Water availability also cues plant phenology and is in flux due to climate change. Earlier rainfall provokes earlier and prolonged flowering seasons (Sakkr et al 2015). Research predicts that rainfall variation will increase due to climate change, destabilizing patterns that plants depend on (Bates et al 2008). Fog events and groundwater availability are associated with phenological advancement in plants (Kidron et al 2002). Climate change may pose a serious risk to fog-reliant areas, increasing or reducing frequency of fog by as much as 30% (Torregrosa et al 2014). Sea level rise will make groundwater more saline and fluctuations in rainfall will make its availability less stable (Bates et al 2008). Changes to temperature, fog, rainfall, and groundwater will differ around the world and may occur slowly. There is a need for long term monitoring at sites where these variables and their relationships to plant phenology are being studied. Long term monitoring of ecological systems is an important way to record changes and make predictions for future climate change impacts (Magurran 2010). Monitoring plant phenology is especially crucial in extreme environments with few species and sensitively balanced ecology. The Namib Desert, with its famous !nara (Acanthosicyos horridus) shrub, fits the bill. The !nara provides food and shelter to animals, and fruit and seeds to the local Topnaar people (Maggs- Kölling 2014; Henschel et al 2004). The !nara has been a long term focus of study at The Gobabeb Research and Training Center, particularly for visiting Dartmouth students in 2013 and 2014. Dartmouth groups have recorded !nara plant size, flower and fruit count, and have also set up a long term monitoring program. Beitler et al (2014) found that between November 2013 and 2014, live biomass and total fruit count decreased in the !Nara Valley. Our research, in conjunction with Gardiner et al (2015), provides an additional year of data on fruit counts and live biomass for the nearby Gobabeb Valley and initiates long term monitoring there. We also add a second year of data to the pollination study initiated by Beitler et al (2014). Due to the regional variability of climate change impacts, studying the Namib Desert at a small scale is essential before understanding the impacts of climate change on the !nara throughout Namibia. Finally, we 3 conducted new research on !nara phenology, as this has been minimally researched and may change due to climate change. Fog in the Namib Desert In and around the Namib Desert, the fog-rainfall gradient creates a stark contrast between the coastal and inland environments (Hachfeld and Jurgens 2000). For areas nearer to the coast, fog is a central source of moisture for plants and animals. Advection fog is transported by the Benguela current and moves from the southwest. The southwesterly wind, one of the region’s two prevailing winds, carries the sea fog inland from the Atlantic Ocean, pummeling dunes and vegetation in the Namib with costal sand. This keeps the coast considerably colder and more humid than areas further inland (Dirkx et al 2008). Inland, plants source their water from small amounts rainfall rather than fog (Hachfeld and Jurgens 2000). Inland, the climate is generally very hot and dry due to the comparative absence of fog. Gobabeb Research and Training Center is situated in the middle of the fog-rainfall gradient. At Gobabeb, rainfall varies from 0 to 200mm per year, averaging around 22mm. The importance of fog for plants around Gobabeb is unclear. Ecosystems in sensitive desert environments with limited water are vulnerable to even small changes in fog or rainfall induced by climate change. Temperature increases for Namibia in the twentieth century were three times the global average (Schneider et al 2015). Climate modeling for 2036-65 predicts surface temperature increases of 0.6-3.5 degrees Celsius. Temperature increases are estimated to be less dramatic near coastal areas and more severe inland (Schneider et al 2015). Unfortunately, most other impacts of climate change on the Namib are still unknown, particularly fog (Turpie et al 2010; Dieckmann et al 2013; Schneider et al 2015). One study using on-the-ground capture and satellite imagery predicts an increase in fog days per year for coastal areas and a decrease inland, with a strengthening of the southwesterly winds that carry fog (Haensler et al 2011; Dirkx et al 2008). Rainfall patterns are expected to change, but different models have predicted both an increase and a decrease in rainfall across the Namib (Schneider et al 2015: 11). The Namib Desert experiences dry spells linked to El Niño events, and climate change is expected to cause more erratic weather events and reduce the predictability of seasonal river floods (Dieckmann et al 2013). Sea level rise will increase flooding along the western Namibian coast. Saltwater intrusion into underground aquifers will likely decrease the survival of plants that rely on groundwater. Overall, the future quality and availability of fog, rainfall, and groundwater – the sources of water that the !nara requires for survival – are uncertain. Changes in water availability make the !nara vulnerable to changes in phenology. !Nara Phenology Research Male !nara flower year-round but the peak of the flowering season for female plants runs October- December (Henschel et al 2004). Our research occurs during the apex of the female plant flowering season. Our two primary study sites are in the Kuiseb Delta near the Atlantic coast, and at Gobabeb, which is inland and southeast of the Delta site. We explore the differences in !nara flower and fruit productivity and phenological advancement within and between these sites. Factors that may impact phenology and productivity include fog, rainfall, and groundwater. The extent to which !nara relies on fog remains unknown. Soderberg (2010) suggests that the !nara receives water from groundwater, but the plant’s architecture, with its intertwined branches, wax 4 bloom, grooved stems and conical thorns, implies fog interception and drip (Malik et al 2014). The !nara is