Neotropical secondary forest succession : changes in structural and functional characteristics

Recognition of the importance of land-use history and its legacies in most ecological systems has been a major factor driving the recent focus on human activity as a legitimate and essential subject of environmental science. Ecologists, conservationists, and natural resource policymakers now recognize that the legacies of land-use activities continue to influence ecosystem structure and function for decades or centuries—or even longer—after those activities have ceased. Consequently, recognition of these historical legacies adds explanatory power to our understanding of modern conditions at scales from organisms to the globe and reduces missteps in anticipating or managing for future conditions. As a result, environmental history emerges as an integral part of ecological science and conservation planning. By considering diverse ecological phenomena, ranging from biodiversity and biogeochemical cycles to ecosystem resilience to anthropogenic stress, and by examining terrestrial and aquatic ecosyst...

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The Importance of Land-Use Legacies to Ecology and Conservation

Land-use history interacts with natural forces to influence the severity of disturbance events and the rate and nature of recovery processes in tropical forests. Although we are far from an integrated view of forest recovery processes, some generalizations can be made. Recovery of forest structure and composition is relatively rapid following disturbances that primarily impact forest canopies, such as hurricanes. Recovery is considerably slower following disturbances that heavily impact soils as well as aboveground vegetation, such as bulldozing, heavy or long-term grazing, and severe fires, often with long-lasting effects on species composition. The landscape matrix plays a critical role in local recovery processes. Proximity of disturbed areas to remnant forest patches promotes more rapid recovery, which depends heavily on seed dispersal. Recovery of aboveground biomass is constrained by soil fertility and texture across regions as well as across soil types within a region. Restoration of soil fertility may be a prerequisite for forest recovery on sites with severely degraded soils. Despite evidence of rapid forest recovery following large-scale deforestation, many degraded areas of today’s tropics will require human assistance to recover forest structure, species composition, and species interactions typical of mature tropical forests.

/pdf/tropical-forest-recovery-legacies-of-human-impact-and-5edfv11o8p.pdf

Tropical forest recovery: legacies of human impact and natural disturbances

Testing against historical data is an important step for validating integrated models of global environmental change. Owing to long time lags in the climate system, these models should aim the simulation of the land use dynamics for long periods, i.e., spanning decades up to a century. Developing such models requires understanding of past and current trends and is therefore strongly data dependent. For this purpose, a history database of the global environment has been developed: HYDE. This paper describes and analyzes parts of HYDE version 2.0, presenting historical population and land use patterns for the past 300 years. Results suggest, among other things, a global increase of cropland area from 265 million ha in 1700 to 1471 million ha in 1990, while the area of pasture has increased more than six fold from 524 to 3451 million ha. In general, the increase of man-made agricultural land took place at the expense of natural grasslands and to a lesser extent of forests. There are differences between the several regions in the temporal pace of these land use conversions. The temperate/developed regions of Canada, United States, USSR, and Oceania appear to have had their strongest increase during the 19th century, while most of the tropical/developing regions witnessed the largest land use conversions at the end of the last century. Results of this analysis can be used to test integrated models of global change and are available at http://www.rivm.nl/env/int/hyde/.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999GB001232

Estimating global land use change over the past 300 years: The HYDE Database

https://www.fs.fed.us/global/iitf/pubs/catalyzing_native_parrotta_etal.pdf

Catalyzing native forest regeneration on degraded tropical lands

Forest recovery in abandoned tropical pastures in Puerto Rico

Anthropogenic alteration of the landscape is a long-term disturbance both in duration and consequences. This study addresses land-cover responses to a history of human land use in northeastern Puerto Rico. Analysis of aerial photographs indicated that the pattern of land use in the municipality of Luquillo changed dramatically between 1936 and 1988. In 1936, sugar cane and pasture were the dominant land uses, occupying about one third of the study area each, while dense forest was rare. Pasture still occupied about a quarter of the area by 1988, but the area of sugai cane had declined to zero. Most sugar cane land was transformed to pasture after abandonment, while much of the pasture at higher elevations reverted to forest. More than half the study area in 1988 was occupied by dense forest, and the degree of forest regeneration was greatest adjacent to the Luquillo Experimental Forest and around patches that were dense forest remnants in 1936. The overall trend was from high-intensity agriculture to dense forest, but urban areas increased more than 2000 percent between 1936 and 1988 and are presently encroaching on forested areas. It is unclear from one study whether the same pattern would hold true at other sites in the tropics, but our study indicates the importance of preserving remnants of mature forest as sources of forest regeneration. In addition, the nature of the patches in the Luquillo landscape has changed as the land use has changed. In 1936, dense forest was highly fragmented, the patches were small and many of them had linear configurations (riparian corridors and hedgerows). By 1988, the average patch size of dense forest had increased greatly, although with one exception the patches were still small relative to other land-cover types.

Land-use dynamics in a post-agricultural puerto rican landscape (1936-1988)

Effects of land management and a recent hurricane on forest structure and composition in the Luquillo Experimental Forest, Puerto Rico

Although deforestation continues to be a major threat to tropical biodiversity, abandonment of agricultural land in Puerto Rico provides an opportunity to study long-term patterns of secondary forest regeneration. Using aerial photographs from 1937, 1967, and 1995, we determined land-use history for 2443 ha in the Cayey Mountains. Pastures were the dominant land cover in 1937 and <20% of the area was classified as forest. Between 1937 and 1995, forest cover increased to 62% due to widespread abandonment of agriculture. To examine the effect of historic land use on current forest structure and species composition, we sampled secondary forests in 24 abandoned pastures, 9 abandoned coffee plantations and 4 old-growth forest sites. Sites were located on two soil types along an elevational gradient (125–710 m) and included a chronosequence from 4 to over 80 years old. After 25–30 years, basal area and species richness in secondary forest sites derived from abandoned pastures and coffee plantations were similar to old-growth forest sites. The species composition of secondary forests derived from abandoned pastures and coffee plantations remained distinct from old-growth forest. In addition to historic land use, age and elevation were important environmental variables explaining variation in secondary forest species composition. Non-indigenous species were common in recently abandoned pastures and coffee plantations, but their importance declined in the older sites. This study demonstrates that secondary forests on private land can be an important component of the conservation of tropical tree biodiversity.

Mayra Serrano

Papers

Forest recovery in abandoned tropical pastures in Puerto Rico

Land-use dynamics in a post-agricultural puerto rican landscape (1936-1988)

Effects of land management and a recent hurricane on forest structure and composition in the Luquillo Experimental Forest, Puerto Rico

Land-Use History and Forest Regeneration in the Cayey Mountains, Puerto Rico