Assessing woody vegetation recovery in the Rayas River following the eruption of the Chaitén Volcano in 2008

We studied the recovery of the woody vegetation in a segment of the Rayas River, that drains the Chaitén Volcano, in southern Chile. Data collection in the river corridor was performed to assess the regeneration rates of the colonizing vegetation within the river corridor, to investigate the site-specific regeneration modes (i.e., with respect to the different morphological units), to determine the species composition and to observe potential similarities with the regeneration process on hillslopes (i.e., outside the river corridor). We first performed a sampling of the shrub and tree vegetation regenerating in the Forest adjacent to the study segment. Further samplings were executed on Islands, High bars, the Floodplain, and in association to Wood jams. Results show that nine years after the volcano's last eruption, pre-eruption remnant Islands and the Floodplain exhibited an abundant regeneration, with the highest density of recruits and species richness. In addition, a clear difference was observed between the river corridor and the Forest, both in the characteristics of the plants that were regenerating as well as in the species composition. Finally, the vegetation that has re-established after the eruption have not yet acquired the capacity to play a stabilizing role in the fluvial corridor. New insights are provided on reforestation patterns at sites impacted by Large Infrequent Disturbances.

Improving Estimation of Woody Aboveground Biomass of Sparse Mixed Forest over Dryland Ecosystem by Combining Landsat-8, GaoFen-2, and UAV Imagery

Sparse mixed forest with trees, shrubs, and green herbaceous vegetation is a typical landscape in the afforestation areas in northwestern China. It is a great challenge to accurately estimate the woody aboveground biomass (AGB) of a sparse mixed forest with heterogeneous woody vegetation types and background types. In this study, a novel woody AGB estimation methodology (VI-AGB model stratified based on herbaceous vegetation coverage) using a combination of Landsat-8, GaoFen-2, and unmanned aerial vehicle (UAV) images was developed. The results show the following: (1) the woody and herbaceous canopy can be accurately identified using the object-based support vector machine (SVM) classification method based on UAV red-green-blue (RGB) images, with an average overall accuracy and kappa coefficient of 93.44% and 0.91, respectively; (2) compared with the estimation uncertainties of the woody coverage-AGB models without considering the woody vegetation types (RMSE = 14.98 t∙ha−1 and rRMSE = 96.31%), the woody coverage-AGB models stratified based on five woody species (RMSE = 5.82 t∙ha−1 and rRMSE = 37.46%) were 61.1% lower; (3) of the six VIs used in this study, the near-infrared reflectance of pure vegetation (NIRv)-AGB model performed best (RMSE = 7.91 t∙ha−1 and rRMSE = 50.89%), but its performance was still seriously affected by the heterogeneity of the green herbaceous coverage. The normalized difference moisture index (NDMI)-AGB model was the least sensitive to the background. The stratification-based VI-AGB models considering the herbaceous vegetation coverage derived from GaoFen-2 and UAV images can significantly improve the accuracy of the woody AGB estimated using only Landsat VIs, with the RMSE and rRMSE of 6.6 t∙ha−1 and 42.43% for the stratification-based NIRv-AGB models. High spatial resolution information derived from UAV and satellite images has a great potential for improving the woody AGB estimated using only Landsat images in sparsely vegetated areas. This study presents a practical method of estimating woody AGB in sparse mixed forest in dryland areas.

Biomass and mortmass of woody vegetation in metal-contaminated areas (Southern Urals, Russia)

Since the mid-2000s, long-term monitoring of various components of natural ecosystems under conditions of industrial pollution has been carried out in the Southern Urals. As a part of these monitoring programmes, the data on various components of biota in different biotopes, collected with different methods and in different time intervals, continue to be gathered. In addition, data collected through these monitoring programmes can also be used to study the local biodiversity of non-polluted areas. In 2012, in the vicinity of the Karabash Copper Smelter, a study of communities of small mammals was carried out, considering the heterogeneity of their habitats. Within the framework of this project, we presented a detailed description of the state of woody vegetation in the study area. The dataset (available from the GBIF network at https://www.gbif.org/dataset/61384edd-2d0a-437b-8cf0-ff4d2dfcc0da) includes the results of an assessment of the woody vegetation biomass at seven habitats (pine, birch and floodplain forests, reed swamp, sparse birch stand, marshy meadow and dump of household waste) of areas with different levels of industrial pollution in the vicinities of the Karabash, the Southern Urals. Karabash Copper Smelter (KCS) is one of Russia’s most significant point polluters; the main components of its emissions are heavy metals, dust and sulphur dioxide. Parameters of woody vegetation (diameter at breast height, diameter at root collar level and biomass) were estimated for seven forest elements (forest stand, subcanopy (undergrowth and underwood), half-dead tree of a forest stand and four types of coarse woody debris (downed bole, fragment of downed bole, standing dead tree and stump)) at 41 sampling plots (20 at unpolluted and 21 at polluted areas) and 165 subplots (81 and 84, respectively). The dataset includes 411 sampling events (estimation events of the forest elements at sampling plots and subplots), corresponding to 5786 occurrences (estimations of the woody vegetation components) observed during July 2012. For most woody vegetation components (72%), an estimate of the above-ground phytomass is given. For each sampling event, information on the presence or absence of woody vegetation species at the considered habitats is provided (a total of 1479 occurrences with status "absent"). The dataset can be used for environmental monitoring, sustainable forest management, modelling forest productivity considering global changes, studying the structure and biodiversity of forest cover and assessing forests’ carbon-sequestration capacity. In addition, the dataset provides information about different forest ecosystems under the influence of strong industrial pollution.

Vegetation and Landscape Dynamics in Eastern Taranaki Hill Country

<p>An ecological study of hill country landscapes in eastern Taranaki, New Zealand, was undertaken as part of a project concerning the implications of long-term soil mantle changes for sustainable land use. The study was undertaken in a 417 km2 area comprising uplifted and steeply dissected soft Tertiary sediments with a predominantly sandstone lithology. Rapid European settlement in the 1890s modified the natural vegetation cover greatly, so that most remaining forest in the study area occurs in patches surrounded by a matrix of pastoral land. Vegetational and successional patterns and environmental variation : The pattern of woody vegetation was investigated by extensive reconnaissance sampling incorporating semi-quantitative analysis of canopy cover, followed by intensive, environmentally stratified sampling. The vegetation was classified on a structural and floristic basis into 19 units of forest, treeland, scrub and shrubland. The effect of environmental variation on vegetation composition was investigated by reciprocal averaging ordination (DECORANA). The first ordination axis was correlated to vegetation structure and canopy height and was interpreted as a complex disturbance gradient relating to time since disturbance. The second and third axes were related to soil fertility and topographical gradients. Forest plots were dominated by Beilschmiedia tawa and Weinmannia racemosa and had basal area values of up to >250 m2/ha. Basal area, stem and seedling density varied greatly between vegetation structural groups. Regeneration of woody vegetation following various types of disturbance: The disturbance regime was comprehensively documented. Main factors of natural disturbance are landslide erosion and windthrow; main factors of cultural disturbance are direct clearance by felling and burning, and introduced animals. A chronology is presented of successional pathways for about 400 years following major disturbance. Succession proceeds through shrubland and scrub stages dominated by treeferns, Leptospermwn scoparium or other broadleaved woody shrubs, through treeland, to broadleaved forest dominated firstly by W. racemosa or Knightia excelsa, then by B. tawa. Podocarp trees are generally only prominent after a long period of uninterrupted succession. Seedling recruitment, mortality and growth were monitored for 2 years. Seedling dynamics varied considerably between and within sampling plots, some of which contained small exclosures that excluded possums and goats. The effects of introduced animals on seedling recruitment and vegetation growth is strongly modified by microtopography. Most dominant species showed continuous regeneration at the scale of the whole study area, despite local discontinuities. This pattern was consistent with a model of interrpted gap-phase regeneration, which may be widely applicable to New Zealand lowland forests. The vegetation turnover time is in the order of 150-250 years, a period consistent with comparable temperate forest ecosystems. The successional pathway is primarily dependent on topography, previous site history and location and area of disturbance. The existence of residual-soils on landslide scars, variations in plant propagule supply, and rapid loss of soil from steep slopes cleared for agriculture, all suggest that a rigid distinction between primary and secondary succession in the study area is not appropriate. Hillslope processes underlying vegetation and landscape change: Hillslope processes were studied in five 0.1 ha plots in which slope profiles were measured, vegetation and microtopography mapped in detail, vegetation age assessed and soil properties investigated. Ground surface age was assessed as an interpretation of the above data. Mean surface age was c. 450 years, but some swales had a surface age of several thousand years. There was a significant correlation between surface age and soil depth, soil depth increase being faster and continuing for much longer under forest than under pasture. Observations were made of near-surface erosion processes such as soil creep. A model of hillslope erosion is outlined, involving periodic evacuation of swales by landslides and refilling of swales by near-surface erosion. Evidence of past environments supports a fluvial origin for swales in an early Ohakean (glacial maximum) or pre-Ohakean period of high erosion. A concluding synthesis of vegetation, topography and soils emphasises the importance of selecting appropriate temporal and spatial scales at which to study landscape processes.</p>

Vegetation and Landscape Dynamics in Eastern Taranaki Hill Country

<p>An ecological study of hill country landscapes in eastern Taranaki, New Zealand, was undertaken as part of a project concerning the implications of long-term soil mantle changes for sustainable land use. The study was undertaken in a 417 km2 area comprising uplifted and steeply dissected soft Tertiary sediments with a predominantly sandstone lithology. Rapid European settlement in the 1890s modified the natural vegetation cover greatly, so that most remaining forest in the study area occurs in patches surrounded by a matrix of pastoral land. Vegetational and successional patterns and environmental variation : The pattern of woody vegetation was investigated by extensive reconnaissance sampling incorporating semi-quantitative analysis of canopy cover, followed by intensive, environmentally stratified sampling. The vegetation was classified on a structural and floristic basis into 19 units of forest, treeland, scrub and shrubland. The effect of environmental variation on vegetation composition was investigated by reciprocal averaging ordination (DECORANA). The first ordination axis was correlated to vegetation structure and canopy height and was interpreted as a complex disturbance gradient relating to time since disturbance. The second and third axes were related to soil fertility and topographical gradients. Forest plots were dominated by Beilschmiedia tawa and Weinmannia racemosa and had basal area values of up to >250 m2/ha. Basal area, stem and seedling density varied greatly between vegetation structural groups. Regeneration of woody vegetation following various types of disturbance: The disturbance regime was comprehensively documented. Main factors of natural disturbance are landslide erosion and windthrow; main factors of cultural disturbance are direct clearance by felling and burning, and introduced animals. A chronology is presented of successional pathways for about 400 years following major disturbance. Succession proceeds through shrubland and scrub stages dominated by treeferns, Leptospermwn scoparium or other broadleaved woody shrubs, through treeland, to broadleaved forest dominated firstly by W. racemosa or Knightia excelsa, then by B. tawa. Podocarp trees are generally only prominent after a long period of uninterrupted succession. Seedling recruitment, mortality and growth were monitored for 2 years. Seedling dynamics varied considerably between and within sampling plots, some of which contained small exclosures that excluded possums and goats. The effects of introduced animals on seedling recruitment and vegetation growth is strongly modified by microtopography. Most dominant species showed continuous regeneration at the scale of the whole study area, despite local discontinuities. This pattern was consistent with a model of interrpted gap-phase regeneration, which may be widely applicable to New Zealand lowland forests. The vegetation turnover time is in the order of 150-250 years, a period consistent with comparable temperate forest ecosystems. The successional pathway is primarily dependent on topography, previous site history and location and area of disturbance. The existence of residual-soils on landslide scars, variations in plant propagule supply, and rapid loss of soil from steep slopes cleared for agriculture, all suggest that a rigid distinction between primary and secondary succession in the study area is not appropriate. Hillslope processes underlying vegetation and landscape change: Hillslope processes were studied in five 0.1 ha plots in which slope profiles were measured, vegetation and microtopography mapped in detail, vegetation age assessed and soil properties investigated. Ground surface age was assessed as an interpretation of the above data. Mean surface age was c. 450 years, but some swales had a surface age of several thousand years. There was a significant correlation between surface age and soil depth, soil depth increase being faster and continuing for much longer under forest than under pasture. Observations were made of near-surface erosion processes such as soil creep. A model of hillslope erosion is outlined, involving periodic evacuation of swales by landslides and refilling of swales by near-surface erosion. Evidence of past environments supports a fluvial origin for swales in an early Ohakean (glacial maximum) or pre-Ohakean period of high erosion. A concluding synthesis of vegetation, topography and soils emphasises the importance of selecting appropriate temporal and spatial scales at which to study landscape processes.</p>

Conservation Priorities in Terrestrial Protected Areas for Latin America and the Caribbean Based on an Ecoregional Analysis of Woody Vegetation Change, 2001–2010

We determined protected area coverage and woody vegetation change in Latin America and the Caribbean at biome and ecoregion scales, for the years 2001 to 2010. For each ecoregion’s terrestrial protected area (TPA) and unprotected area, a linear regression of woody vegetation area against time (10 years) was used to estimate 2001 and 2010 woody vegetation, respectively. We calculated a conversion-to-protection index, termed the Woody Conservation Risk Index, and identified trends in relation to existing conservation priorities. As a whole, the region lost 2.2% of its woody cover. High woody cover loss was observed for the Moist Forests (3.4% decrease) and the Flooded Grasslands/Savannas (11.2% decrease) biomes, while Mediterranean Forests exhibited a 5.8% increase. The Dry Forest Biome, the most threatened biome worldwide, experienced a 2% regional gain, which was surprising as we expected the opposite given a net regional loss for all biomes. Woody cover was more stable in TPAs in comparison to areas with no protection. Deforestation inside and surrounding TPAs remains high in humid ecoregions. High overall ecoregion deforestation, with stable TPAs, characterized some Amazonian ecoregions, the Dry Chaco, and moist forests on the eastern Andean foothills of Ecuador and Peru. Woody regrowth inside and outside of TPAs was observed in the Sonoran-Sinaloan transition subtropical dry forests and the Sierra Madre Occidental pine-oak forests in Mexico.