Spatial distributions of reforestation sites, deforestation sites, and unchanged forests (F_F) during the period of 1991–2000.

<p>The forest distribution in the deforestation-only scenario includes the F_F only, while that in the reforestation-only scenario includes all the three types. The true distribution in 1991 includes deforestation sites and unchanged forests; the true distribution in 2000 includes unchanged forests and reforestation sites.</p

Location, geomorphology, and land cover in 2000 of Puerto Rico (Land cover information from Kennaway and Helmer, 2007).

<p>Location, geomorphology, and land cover in 2000 of Puerto Rico (Land cover information from Kennaway and Helmer, 2007).</p

Discerning Fragmentation Dynamics of Tropical Forest and Wetland during Reforestation, Urban Sprawl, and Policy Shifts

<div><p>Despite the overall trend of worldwide deforestation over recent decades, reforestation has also been found and is expected in developing countries undergoing fast urbanization and agriculture abandonment. The consequences of reforestation on landscape patterns are seldom addressed in the literature, despite their importance in evaluating biodiversity and ecosystem functions. By analyzing long-term land cover changes in Puerto Rico, a rapidly reforested (6 to 42% during 1940–2000) and urbanized tropical island, we detected significantly different patterns of fragmentation and underlying mechanisms among forests, urban areas, and wetlands. Forest fragmentation is often associated with deforestation. However, we also found significant fragmentation during reforestation. Urban sprawl and suburb development have a dominant impact on forest fragmentation. Reforestation mostly occurs along forest edges, while significant deforestation occurs in forest interiors. The deforestation process has a much stronger impact on forest fragmentation than the reforestation process due to their different spatial configurations. In contrast, despite the strong interference of coastal urbanization, wetland aggregation has occurred due to the effective implementation of laws/regulations for wetland protection. The peak forest fragmentation shifted toward rural areas, indicating progressively more fragmentation in forest interiors. This shift is synchronous with the accelerated urban sprawl as indicated by the accelerated shift of the peak fragmentation index of urban cover toward rural areas, i.e., 1.37% yr⁻¹ in 1977–1991 versus 2.17% yr⁻¹ in 1991–2000. Based on the expected global urbanization and the regional forest transition from deforested to reforested, the fragmented forests and aggregated wetlands in this study highlight possible forest fragmentation processes during reforestation in an assessment of biodiversity and functions and suggest effective laws/regulations in land planning to reduce future fragmentation.</p></div

Description of the eight watersheds in Puerto Rico.

<p>Description of the eight watersheds in Puerto Rico.</p

Landscape parameters and annual rainfall averaged over the 1981–2013 period for eight watersheds.

<p><i>A</i> stands for land cover fraction of total watershed area, <i>P</i> is perimeter-to-area ratio, an index for shape irregularity and patchiness or fragmentation. Subscripts <i>a</i>, <i>u</i>, <i>f</i>, and <i>g</i> stand for agriculture, urban land, forest, and grassland/pasture, respectively.</p

Island-wide fragmentation analyses for urban, forest, and wetland areas in 1991 and 2000.

<p>AREA_MN, mean patch area (ha); LPI, largest patch index (%); ED, edge density (m ha⁻¹); EDGE_AREA, edge to area ratio (m m⁻²).</p><p>Island-wide fragmentation analyses for urban, forest, and wetland areas in 1991 and 2000.</p

The fragmentation indices used in the landscape analysis.

<p>The fragmentation indices used in the landscape analysis.</p

Simulated monthly mean discharge with the land cover map of 2000 versus USGS gauged data for LOZ, CBC, MNT, and CLR.

<p>All the correlation coefficients have <i>p</i>-values less than 0.01. <i>r</i> is the Pearson’s correlation coefficients, <i>s</i> is the root mean square of the error.</p

Fragmentation dynamics of (a) urban edge density (ED, m ha⁻¹), (b) forest mean patch area (AREA_MN, ha), and (c) wetland edge-to-area ratio (EDGE_AREA, m m⁻²) in 1977, 1991, and 2000.

<p>Fragmentation dynamics of (a) urban edge density (ED, m ha⁻¹), (b) forest mean patch area (AREA_MN, ha), and (c) wetland edge-to-area ratio (EDGE_AREA, m m⁻²) in 1977, 1991, and 2000.</p

Watersheds in this study.

<p>FJD, Rio Fajardo, ESS, Rio Espiritu Santo, BLC, Rio Blanco, GRB, Rio Gurabo, LOZ, Rio Grande de Loiza, CBC, Rio Cibuco, MNT, Rio Grande de Manati, and CLR, Rio Culebrinas. Green points represent the meteorological stations used in the simulation. The background topography information is for illustration only (Data publicly accessible from <a href="https://lta.cr.usgs.gov/SRTM1Arc" target="_blank">https://lta.cr.usgs.gov/SRTM1Arc</a>).</p