Comparing and contrasting flooded and unflooded forests in western Amazonia: seed predation, seed pathogens, germination

Abstract

Abstract:Because of the importance of the Amazon to our shared human future and because we need to understand how its forests regenerate, I set out seeds for a week in igapó, palm, terra firme, várzea and white sand forests and then collected them, scoring seed losses to predators, seed losses to pathogens and seeds that germinated. I found (1) terra firme forest, white sand forest, várzea forest and igapó forest under water 1 month every year, were significantly different for seed mechanisms and tolerances, terra firme forest, palm forest, várzea forest and igap� forest under water 1 month per year, were signifi cantly difigap� forest under water 1 month per year, were signifi cantly difwere significantly different among species, and the interaction term was significant for all forests except for the two most flooded igapó forests, (2) in terra firme forest seed predators took most seeds regardless of species, (3) in palm forest species were different regardless of seed mechanism and tolerance, (4) in white sand forest seed predators took most seeds regardless of species, (5) in várzea forest seed predators took most seeds but with some species differences and (6) in igapó forest under water 1 month per year, there were differences in predation, pathogens and germination, and in species variation. I conclude that seed predation losses strength as forests become more stressed either by loss of soil fertility or by flooding with nutrient-poor water. Conversely seed pathogens become more important with water-logged soils and with flooding. Seed loss variation among species within forests was always a secondary factor.

Effects of Soil Type on Floristics and Stand Structure in Amazon Unflooded Forests

“…That is while seed predation losses strength as forests become more stressed by loss of soil fertility, seed pathogens become more important with water-logged soils (Myster, 2017b). These permanent plot studies, and others like them in the Amazon, provide baseline data on forest dynamics and fluctuations of forest structure which are due to plant-plant replacement (Myster, 2012;Myster, 2017a).…”

Effects of selective-logging, litter and tree species on forests in the Peruvian Amazon: seed predation, seed pathogens, germination

“…This must be due to critical sources of variation (SOV) in how these mechanisms (seed predation, seed pathogens) and environmental tolerances (seed germination) work. While many of these SOV have been investigated in Amazon forests -for example variation among species, variation among microsites created by tree fall and conversion to agriculture, variation in the amount of litter, variation among different seasons, variation among different years and variation at different spatial scales (Bodmer 1991, Notman et al 1996, Notman & Gorchov 2001, Russo 2005, Vieira & Scariot 2006, Paine and Beck 2007, Myster 2012, Myster 2014, Myster 2015, Myster 2017b) -we need more information in how seed mechanisms and tolerances work.…”

“…Therefore because of the importance of these forests, and the need for more investigation into critical SOV of their seed mechanisms and seed tolerances, I continue my past research into recruitment of Amazon unflooded forests (Myster 2012, Myster 2014, Myster 2017b) by conducting new field experiments on how selectivelogging, different tree seed species, and addition of litter interact to affect seed predation, seed pathogens, and germination in Amazon unlogged terra firme forest, in Amazon selectively-logged terra firme forest, in Amazon palm forest, and in Amazon white sand forest with litter interactions. I test these five hypotheses:…”

“…(1) Seed predators will take the majority of tree seeds put out in these Amazonian forests with terra firme forests (both selectively-logged and unlogged) having the greatest losses, white sand forests having the least, and palm forests between the two in losses (Bodmer 1991, Notman et al 1996, Russo 2005, Paine & Beck 2007, Myster 2009, Myster 2014, Myster 2017b).…”

“…(2) Seed pathogens will take the majority of tree seeds that predators do not take with palm forests having the greatest losses, white sand forests having the least, and terra firme forests (both selectively-logged and unlogged) between the two in losses (Myster 2017b).…”