Habitat fragmentation is a pervasive and ubiquitous form of global change with myriad detrimental ecological consequences. Various studies have documented altered rates of individual survivorship, reproduction and recruitment for plants in fragments. However, despite well-known critical links between size, reproduction and demography, very few have quantified individual growth rates of plants that survive after fragmentation occurs. Over the course of ten years, we measured annual growth of 5200 individuals of the common understory herb Heliconia acuminata (Heliconiaceae) growing in an experimentally fragmented landscape in Amazonia.To elucidate demographic consequences of variation in growth rates in this long-lived perennial, we also measured number of inflorescences produced as a measure of reproductive output. We tested : 1) whether annual growth rates were lower in fragments than in continuous forest, and 2) whether cumulative growth rates of plants that survived the entire period were lower in fragments. 

Results/Conclusions

Although mean annual growth rates were often lower in fragments, the differences were not significant in any year. After ten years, however, the cumulative effect was that plants in fragments were significantly smaller. This reduced cumulative growth had a clear demographic consequence – compared with plants in continuous forest, the smaller plants in fragments produced significantly fewer inflorescences. Our results show that habitat fragmentation can negatively affect individual growth rates of plants, and that these effects can in turn feed back into the demography of plant populations. Our study demonstrates that negative demographic consequences of fragmentation can take years to manifest themselves, and that chronic reduced growth can be an important mechanism contributing to reduced population viability in fragmented landscapes.