The Luquillo LTER has evolved through an iterative process of key conclusions found within each proposal (LUQ I-IV). We initially focused on patch dynamics in one forest type (tabonuco forest) as a unifying theme (LUQ I). In LUQ II we developed the concept of “ecological space” (see Waide & Willig 2012 for history) to describe how antecedent and current conditions influence the biota and biochemical dynamics responding to the disturbance regime. In LUQ III we focused on detrital dynamics as our unifying theme, while expanding our studies to include all of the LEF, including life zones at elevations above tabonuco forest. We studied ecosystem services in LUQ IV, extending our studies to urban and other zones at the base of the Luquillo Mountains. Three main key conclusions were found in LUQ I-III
1. Disturbance shapes the climatic, biotic, and biogeochemical characteristics of the Luquillo Mountains, but responses to disturbance are mediated by initial conditions and characteristics of the disturbance (Waide & Lugo 1992, Walker & Willig 1999, Brokaw et al. 2012). Thus, the effects of disturbance are contingent on previous disturbance events. Hurricanes exert their primary effects through canopy opening and organic matter deposition, in order of importance (Shiels & González 2014).
2. Climate is a primary determinant of the distribution of biota and rates of biogeochemical cycling in the LEF (Barone et al. 2008, González et al. 2013). Long-term directional change in climate is taking place in the LEF, and rates of change are more rapid than previously realized. Both models and empirical data suggest that rainfall is decreasing and temperature is increasing in the Luquillo Mountains (Scatena 1998, van der Molen 2010, Schaefer 2003, González et al. 2013).
3. The interaction between changing climate and disturbance regime will result in ecosystems characterized by novel species compositions, with altered structures, biogeochemistry, and ecosystem services (Doyle 1981, Sanford et al. 1991, Covich et al. 1991, 1996, O’Brien et al. 1992, Silver 1998, Wang et al. 2002a, b, Erickson & Ayala 2004, Dodds 2006, Bouskill et al. 2013). Determining how these new ecosystems will develop and evolve under dynamic climate and disturbance regimes is a long-term theme of LUQ.
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