The fractal shape of riparian forest patches

1990 ◽  
Vol 4 (4) ◽  
pp. 249-258 ◽  
Author(s):  
K. D. Rex ◽  
George P. Malanson
2003 ◽  
Vol 60 (3) ◽  
pp. 425-431 ◽  
Author(s):  
Alexandre Cândido Xavier ◽  
Carlos Alberto Vettorazzi

Leaf Area Index (LAI), an important structural variable descriptive of vegetation, is directly related to evapotranspiration and productivity. The objective of this work was to measure and analyze monthly LAI of different ground covers in a subtropical watershed. A field campaign to collect monthly LAI data was carried out during the year 2001, with a LAI-2000 (plant canopy analyzer) device, in sugarcane, pasture, corn, eucalypt, and riparian forest patches. Riparian forest presented a maximum LAI of 4.90; LAI values decreased as precipitation decreased, as it is a characteristic of this type of semideciduous vegetation. LAI for sugar cane presented the greatest variability throughout the year, related to plant characteristics and crop management in the study area. Results represent an initial step for the understanding of LAI dynamics in the study area and areas under similar conditions.


2019 ◽  
Vol 11 (18) ◽  
pp. 5060 ◽  
Author(s):  
Yirigui ◽  
Lee ◽  
Nejadhashemi

Due to anthropogenic activities within watersheds and riparian areas, stream water quality and ecological communities have been significantly affected by degradation of watershed and stream environments. One critical indicator of anthropogenic activities within watersheds and riparian areas is forest fragmentation, which has been directly linked to poor water quality and ecosystem health in streams. However, the true nature of the relationship between forest fragmentation and stream ecosystem health has not been fully elucidated due to its complex underlying mechanism. The purpose of this study was to examine the relationships of riparian fragmented forest with biological indicators including diatoms, macroinvertebrates, and fish. In addition, we investigated variations in these relationships over multiple riparian scales. Fragmentation metrics, including the number of forest patches (NP), proportion of riparian forest (PLAND), largest riparian forest patch ratio (LPI), and spatial proximity of riparian forest patches (DIVISION), were used to quantify the degree of fragmentation of riparian forests, and the trophic diatom index (TDI), benthic macroinvertebrates index (BMI), and fish assessment index (FAI) were used to represent the biological condition of diatoms, macroinvertebrates, and fish in streams. PLAND and LPI showed positive relationships with TDI, BMI, and FAI, whereas NP and DIVISION were negatively associated with biological indicators at multiple scales. Biological conditions in streams were clearly better when riparian forests were less fragmented. The relationships of NP and PLAND with biological indicators were stronger at a larger riparian scale, whereas relationships of LPI and DIVISION with biological indicators were weaker at a large scale. These results suggest that a much larger spatial range of riparian forests should be considered in forest management and restoration to enhance the biological condition of streams.


2007 ◽  
Vol 34 (3) ◽  
pp. 185 ◽  
Author(s):  
Matthew Johnson ◽  
Paul Reich ◽  
Ralph Mac Nally

Many of the world’s agricultural areas have greatly reduced levels of natural vegetation. This results in highly fragmented mosaic landscapes with multiple land-use types. We examined the importance of vegetation and landscape pattern by comparing the bird assemblages of riparian zones, non-riparian forest patches, and pasture in a fragmented agricultural landscape in south-eastern Australia. Bird surveys were conducted every four weeks at 27 sites in the Goldfields region of central Victoria for one year. The landscape context (position and shape of patches) and vegetation attributes were measured for each site. We found that bird assemblages strongly differed among these landscape elements. Mean abundance was significantly greater at forested patches, and there was a three-fold reduction in species richness at pasture sites. Bird assemblage structure was influenced substantially more by vegetation than by the landscape context of sites. Our results indicate that riparian vegetation is a key element for avian diversity, even in massively altered landscapes. The restoration of riparian vegetation and its connectivity with adjacent forest types would greatly benefit bird assemblages in agricultural areas.


2004 ◽  
Vol 80 (1) ◽  
pp. 44-53 ◽  
Author(s):  
François Potvin ◽  
Normand Bertrand

Riparian forest strips (RS) along lakes and streams have been incorporated in regulations on clearcuts to protect water quality and fish habitat. As well, upland strips (US) are used to limit the size of clearcut patches. We conducted a three-year study to evaluate if RS and US between adjacent cutovers in large clearcut landscapes could be useful for certain terrestrial wildlife. Our study was conducted in southcentral Québec on six landscapes (23–256 km2) originating from black spruce (Picea mariana) forests that were recently logged (≤ 9 years). Residual uncut forest, mostly strips (width = 51–132 m), made up 31% of the productive forest area within these landscapes. RS and US were suitable habitat for red squirrel (Tamiasciurus hudsonicus) and many species of birds including spruce grouse (Falcipennis canadensis). They provided marginal habitat for snowshoe hare (Lepus americanus) and were not preferred by moose (Alces alces) over clearcut areas in winter. One bird species, bay-breasted warbler (Dendroica castanea), was absent in forest strips during the last year. We concluded that leaving RS and US is a management scenario that enables maintaining certain wildlife species within clearcut landscapes, but that larger residual forest patches are needed to accommodate area-sensitive and forest-interior species. A portion of these patches should be allowed to develop into mature and overmature stages for old-growth forest species. Green tree and dead tree retention should also be incorporated in logging practices to accommodate species that need snags for nesting or feeding. In areas where wildlife use has a high priority, large clearcuts should be intermixed with dispersed patch cutting in order to gain social acceptance. Key words: black spruce, forest strip, clearcutting, ecosystem management, Picea mariana, riparian strip


2006 ◽  
Vol 65 (1) ◽  
pp. 147-155 ◽  
Author(s):  
David R. Montgomery ◽  
Tim B. Abbe

AbstractField surveys and radiocarbon dating of buried logjams in the floodplain of an old-growth forest river demonstrate the formation of erosion-resistant “hard points” on the floodplain of the Queets River, Washington. These hard points provide refugia for development of old-growth forest patches in frequently disturbed riparian environments dominated by immature forest. Our surveys show that local bed aggradation associated with logjams not only influences channel patterns and profiles but leads to development of a patchwork of elevated landforms that can coalesce to form portions of the valley bottom with substantial (i.e., 1 to > 4 m) relief above the bankfull elevation. In addition, logjam-formed hard points promote channel avulsion, anastomosing morphology, and growth of mature patches of floodplain forest that, in turn, provide large logs needed to form more logjam-formed hard points. Hence, our findings substantiate the potential for a feedback mechanism through which hard points sustain complex channel morphology and a patchwork floodplain composed of variable-elevation surfaces. Conversely, such a feedback further implies that major changes in riparian forest characteristics associated with land use can lead to dramatic simplification in channel and floodplain morphology.


2020 ◽  
Vol 12 (4) ◽  
pp. 1448 ◽  
Author(s):  
Lea Johnson ◽  
Tara Trammell ◽  
Tracie Bishop ◽  
Joshua Barth ◽  
Scott Drzyzga ◽  
...  

Streamside forests of urbanizing coastal regions lie at the nexus of global changes: rising sea levels, increasing storm surge, expanding urban development, and invasive species. To understand how these combined stressors affect forest conditions, we identified forest patches adjacent to urban land, analyzed adjacent land cover, modeled forest inundation, and sampled 100 sites across the Chesapeake Bay and Delaware Bay watersheds. We found that the majority of forest patches are adjacent to urban land and projected flooding will affect 8–19% of regional forested land. We observed non-native invasive plants in 94% of forest plots. Trees were predominantly native, but over half of shrub stems were invasive species and more than 80% of plots contained invasive woody vines. Disturbance of human origin was correlated with abundance of invasive trees. Signs of deer activity were common. Richness and number of growth forms of invasive plants were related to adjacent agricultural land cover. These data reveal that streamside forests are impacted by the interacting stressors of urbanization, climate change, and invasive species spread. Our results emphasize the importance of protection and restoration of forests in urban regions and point to the need for a social-ecological systems approach to improve their condition.


2010 ◽  
Vol 37 (3) ◽  
pp. 249 ◽  
Author(s):  
Cecilia Smith-Ramirez ◽  
Juan L. Celis-Diez ◽  
Erik von Jenstchyk ◽  
Jaime E. Jimenez ◽  
Juan J. Armesto

Context. Remnant forest patches in rural landscapes may be important sites for maintaining viable populations of restricted forest species, especially when these remnant habitats maintain some connectivity, for instance through riparian vegetation strips and other forest patches. Aims. We assessed the use of remnant forest habitats in a rural landscape of southern Chile (40°S) by the ‘near threatened’ arboreal marsupial Dromiciops gliroides (Microbiotheria), in relation to habitat type (riparian strips, forest fragments and continuous forests), width of the riparian forests, and the presence and abundance of the hemiparasite Tristerix corymbosus, whose fruits are readily eaten by D. gliroides. Methods. In two summers, 2004 and 2008, we set up grids of 96 live traps for three consecutive nights at each of 16 sites along two riparian forest strips, four additional sites in remnant, non-riparian forest patches, and four more within continuous pre-Andean forest. We counted hemiparasites on trees in the trapping grid area, and estimated their individual volumes. Key results . In total, 48 individuals of D. gliroides were captured at all sites during the 2 years. We documented a significant positive relationship between the width of riparian vegetation and the number of individuals captured (r s = 0.78, P = 0.02, n = 8) for one riparian strip, but not for the second one. Neither habitat type nor the frequency of hemiparasites related statistically to D. gliroides abundance. Key conclusions. We conclude that in the rural landscape of the Chilean Lake District, narrow riparian forest strips, in a highly inter-connected mosaic of remnant forest patches may be as important as large patches and continuous Andean forests to sustain viable populations of this threatened, strictly arboreal, marsupial. Implications. The present study reports, for the first time, the presence in narrow riparian forests immersed in a pasture-dominated agricultural matrix of this forest-specialist marsupial, which was previously known only from continuous pre-Andean forests.


2021 ◽  
Vol 16 (3) ◽  
pp. 451-460
Author(s):  
Pablo Marín ◽  
José Manuel Mora ◽  
Lucia I. López ◽  
José Alberto Pérez Arrieta ◽  
Miguel A. Rodríguez ◽  
...  

The northern naked-tailed armadillo, Cabassous centralis, is a rare and elusive species. It ranges from southern Mexico to northern South America. It has been detected in several types of habitats, but appears to prefer Tropical and Subtropical broadleaf forests. In Costa Rica, this species is difficult to observe and there are only eight records reported in the scientific literature. To search records of this armadillo, we used camera traps in north-western Costa Rica and visited several additional localities in the centre and the Caribbean lowlands of the country. We also examined and assessed records of this species from the Global Biodiversity Information Facility (GBIF) database. We added four new locality records for C. centralis in Costa Rica, based on photos from camera traps and field observations. We found only three localities (five records) in GBIF additional to the eight reported in literature. Habitat in these new Costa Rican localities reported here varied from mature dense forest (one site) to semi-urban areas (two sites). Additionally, two individuals were detected in secondary forest patches, one of them adjacent to mature riparian forest. Given the species’ scarcity, much additional information still is required to ground protection actions in a scientific framework.


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