共查询到20条相似文献，搜索用时 15 毫秒
1.
Juan C. lvarez‐Ypiz 《Restoration Ecology》2020,28(2):271-276
Extreme disturbance events denote another aspect of global environmental changes archetypal of the Anthropocene. These events of climatic or anthropic origin are challenging our perceived understanding about how forests respond to disturbance. I present a general framework of tropical forest responses to extreme disturbance events with specific examples from tropical dry forests. The linkage between level of disturbance severity and dominant mechanism of vegetation recovery is reflected on a variety of initial trajectories of forest succession. Accordingly, more realistic and cost‐effective restoration goals in many tropical forests likely consist in maintaining a mosaic of different successional trajectories while promoting landscape connectivity, rather than encouraging full‐ecosystem recovery to pre‐disturbance conditions. Incorporating extreme disturbance events into the global restoration ecology agenda will be essential to design well‐informed ecosystem management strategies in the coming decades. 相似文献
2.
Ervan Rutishauser Stuart J. Wright Richard Condit Stephen P. Hubbell Stuart J. Davies Helene C. Muller‐Landau 《Global Change Biology》2020,26(3):1485-1498
Tropical forest responses to climate and atmospheric change are critical to the future of the global carbon budget. Recent studies have reported increases in estimated above‐ground biomass (EAGB) stocks, productivity, and mortality in old‐growth tropical forests. These increases could reflect a shift in forest functioning due to global change and/or long‐lasting recovery from past disturbance. We introduce a novel approach to disentangle the relative contributions of these mechanisms by decomposing changes in whole‐plot biomass fluxes into contributions from changes in the distribution of gap‐successional stages and changes in fluxes for a given stage. Using 30 years of forest dynamic data at Barro Colorado Island, Panama, we investigated temporal variation in EAGB fluxes as a function of initial EAGB (EAGBi) in 10 × 10 m quadrats. Productivity and mortality fluxes both increased strongly with initial quadrat EAGB. The distribution of EAGB (and thus EAGBi) across quadrats hardly varied over 30 years (and seven censuses). EAGB fluxes as a function of EAGBi varied largely and significantly among census intervals, with notably higher productivity in 1985–1990 associated with recovery from the 1982–1983 El Niño event. Variation in whole‐plot fluxes among census intervals was explained overwhelmingly by variation in fluxes as a function of EAGBi, with essentially no contribution from changes in EAGBi distributions. The high observed temporal variation in productivity and mortality suggests that this forest is very sensitive to climate variability. There was no consistent long‐term trend in productivity, mortality, or biomass in this forest over 30 years, although the temporal variability in productivity and mortality was so strong that it could well mask a substantial trend. Accurate prediction of future tropical forest carbon budgets will require accounting for disturbance‐recovery dynamics and understanding temporal variability in productivity and mortality. 相似文献
3.
David A. Prieto‐Torres Adolfo G. Navarro‐Sigüenza Diego Santiago‐Alarcon Octavio R. Rojas‐Soto 《Global Change Biology》2016,22(1):364-379
Assuming that co‐distributed species are exposed to similar environmental conditions, ecological niche models (ENMs) of bird and plant species inhabiting tropical dry forests (TDFs) in Mexico were developed to evaluate future projections of their distribution for the years 2050 and 2070. We used ENM‐based predictions and climatic data for two Global Climate Models, considering two Representative Concentration Pathway scenarios (RCP4.5/RCP8.5). We also evaluated the effects of habitat loss and the importance of the Mexican system of protected areas (PAs) on the projected models for a more detailed prediction of TDFs and to identify hot spots that require conservation actions. We identified four major distributional areas: the main one located along the Pacific Coast (from Sonora to Chiapas, including the Cape and Bajío regions, and the Balsas river basin), and three isolated areas: the Yucatán peninsula, central Veracruz, and southern Tamaulipas. When considering the effect of habitat loss, a significant reduction (~61%) of the TDFs predicted area occurred, whereas climate‐change models suggested (in comparison with the present distribution model) an increase in area of 3.0–10.0% and 3.0–9.0% for 2050 and 2070, respectively. In future scenarios, TDFs will occupy areas above its current average elevational distribution that are outside of its present geographical range. Our findings show that TDFs may persist in Mexican territory until the middle of the XXI century; however, the challenges about long‐term conservation are partially addressed (only 7% unaffected within the Mexican network of PAs) with the current Mexican PAs network. Based on our ENM approach, we suggest that a combination of models of species inhabiting present TDFs and taking into account change scenarios represent an invaluable tool to create new PAs and ecological corridors, as a response to the increasing levels of habitat destruction and the effects of climate change on this ecosystem. 相似文献
4.
Oleksandra Hararuk Elizabeth M. Campbell Joseph A. Antos Roberta Parish 《Global Change Biology》2019,25(4):1222-1234
Atmospheric CO2 concentrations are now 1.7 times higher than the preindustrial values. Although photosynthetic rates are hypothesized to increase in response to rising atmospheric CO2 concentrations, results from in situ experiments are inconsistent in supporting a CO2 fertilization effect of tree growth. Tree‐ring data provide a historical record of tree‐level productivity that can be used to evaluate long‐term responses of tree growth. We use tree‐ring data from old‐growth, subalpine forests of western Canada that have not had a stand‐replacing disturbance for hundreds of years to determine if growth has increased over 19th and 20th centuries. Our sample consisted of 5,858 trees belonging to five species distributed over two sites in the coastal zone and two in the continental climate of the interior. We calculated annual increments in tree basal area, adjusted these increments for tree size and age, and tested whether there was a detectable temporal trend in tree growth over the 19th and 20th centuries. We found a similar pattern in 20th century growth trends among all species at all sites. Growth during the 19th century was mostly stable or increasing, with the exception of one of the coastal sites, where tree growth was slightly decreasing; whereas growth during the 20th century consistently decreased. The unexpected decrease in growth during the 20th century indicates that there was no CO2 fertilization effect on photosynthesis. We compared the growth trends from our four sites to the trends simulated by seven Earth System Models, and saw that most of the models did not predict these growth declines. Overall, our results indicate that these old‐growth forests are unlikely to increase their carbon storage capacity in response to rising atmospheric CO2, and thus are unlikely to contribute substantially to offsetting future carbon emissions. 相似文献
5.
Gbenga F. Akomolafe Rusly Rosazlina Zakaria Rahmad Fatai A. Oloyede 《Ecology and evolution》2022,12(6)
Research on fern ecology has gained attention in the last decade, yet there is a paucity of information on the comparison of ferns communities across continents. This study focused on comparing the ferns community assemblages in some tropical forests of Malaysia and Nigeria, thereby assessing the patterns of species richness (SR) and phylogenetic diversity (PD) in relation to the bioclimatic drivers across the continents. The diversity and taxonomic compositions of ferns were assessed using 180 plots of 10 m × 10 m in each country. The species richness and other diversity indices were determined using the combined forests data for each country and for the individual forests. Also, the phylogenetic diversity of the ferns was assessed using the genus‐based molecular sequences downloaded from the GeneBank. The patterns of the ferns SR and PD in the two countries as driven by some bioclimatic factors were evaluated using the regression analysis. The observed and rarefied–extrapolated fern species richness is significantly higher in Malaysian forests than in Nigerian forests. Also, the other diversity indices are significantly higher in Malaysian forests except for the Shannon index which showed no significant difference between the two biogeographic regions. There is a very low similarity (7.41%) in the taxonomic composition of ferns between the two biogeographic areas, although the similarity in composition increased with increasing taxonomic levels (species: 7.41%, genus: 12.77%, family: 70.96%). Terrestrial and epiphytic ferns are more dominant than the other life forms in the two countries. The precipitation variables drive the phylogenetic structure of ferns in Nigeria, whereas both precipitation and temperature variables drive the phylogenetic structure of ferns in Malaysia. This indicates that ferns assemblages in Nigeria and Malaysia are driven by both climatic variables. Besides, we also hypothesize that these observed differences could be due to other historical and evolutionary processes. 相似文献
6.
Marcelo Tabarelli 《Biotropica》2010,42(5):553-554
Many conservationists are now convinced that the expansion of the world system of protected areas combined with appropriate levels of biodiversity persistence within human-modified landscapes would drastically mitigate the announced impoverishment of tropical biotas. In this context, an inherent/intrinsic biodiversity ability to persist and recover within human-modified landscapes has emerged as a ‘trump card’ in the conservation battle, renewing our hope in a more sustainable development of the tropical region. However, this optimistic perspective on the conservation value of human-modified landscapes sounds, a priori, a little unrealistic in face of the current knowledge on the nature of human environments and the spectrum of native species that is likely to persist there. Rather than relying on illusory levels of biodiversity resilience and consequent flexible land-use regulations, our real trump card reposes on a radical and ambitious shift from freely exploited landscapes to strictly managed ones, despite the misleading noise produced by those voices advocating for immediate and almost unlimited access to natural resources. Otherwise, we are condemning future human populations to live in biologically impoverished and fragile environments with limited opportunities for life support. 相似文献
7.
Litterfall is an essential component of tropical forest productivity, transferring nutrients from the vegetation back to soils. Here, we summarize the data from 105 estimates of fine litterfall production from 45 sites in the Atlantic Forest domain, including two types of forests, evergreen and seasonal, and two successional stages, secondary and old growth. The overall litterfall average was 8.0 ± 2.5 Mg/ha. Litterfall was significantly in higher seasonal forests than in evergreen forests and in old growth versus secondary forests. Leaves were the major component of litterfall, contributing 68 percent to the total. The second most important component was branches, contributing 22 percent, followed by reproductive organs (flowers and fruits), at 6 percent. Accurate measurements of tropical forest productivity are crucial for estimating their role in sequestering atmospheric carbon, and we suggest some ways to standardize litterfall sampling to obtain better estimates. 相似文献
8.
Drought and pests are primary abiotic and biotic factors proposed as selective filters acting on species distributions along rainfall gradients in tropical forests and may contribute importantly to species distributional limits, performance, and diversity gradients. Recent research demonstrates linkages between species distributions along rainfall gradients and physiological drought tolerance; corresponding experimental examinations of the contribution of pest pressure to distributional limits and potential interactions between drought and herbivory are limited. This study aims to quantitate differential performance and herbivory as a function of species range limits across a climatic and floristic transition in Southeast Asia. Khao Chong Botanical Garden, Thailand and Pasoh Forest Reserve, Malaysia straddle the Kangar‐Pattani Line. A reciprocal transplantation across a seasonality gradient was established using two groups of species (“widespread” taxa whose distributions include seasonally dry forests and “aseasonal” taxa whose distributions are limited to aseasonal forests). Growth, biomass allocation, survival, and herbivory were monitored for 19 months. Systematic differences in performance were a function of species distribution in relation to rainfall seasonality. In aseasonal Pasoh, aseasonal species had both greater growth and survivorship than widespread species. These differences were not a function of differential herbivory as widespread and aseasonal species experienced similar damage in the aseasonal forest. In seasonally dry Khao Chong, widespread species showed higher survivorship than aseasonal species, but these differences were only apparent during drought. We link this differential performance to physiological mechanisms as well as differential tolerance of biotic pressure during drought stress. Systematic decreases in seedling survival in aseasonal taxa during drought corresponded with previously documented physiological differences and may be exacerbated by herbivore damage. These results have important implications for tropical diversity and community composition in light of predicted increases in the frequency and severity of drought in hyperdiverse tropical forests. 相似文献
9.
Julieta Benitez‐Malvido 《Biotropica》2006,38(2):171-182
I assessed the role of low vegetation (plants ca 1 yr old and ≤50 cm tall) as a biotic facilitator or barrier in the recruitment of different growth forms and species in primary forests, secondary forests, and old‐fields (abandoned pastures) in southeastern Mexico. I removed by hand all plants (≤100 cm tall, including roots) and litter from 20, 0.25 m2 plots in each habitat. For 1 yr, I counted the number of plant species (5–50 cm tall) recruited, grouped them into different growth forms, and compared them to undisturbed control plots. Prior to manipulation, the standing density of trees and lianas was highest in primary and secondary forests. Shrubs were more abundant in secondary forests, whereas herbs, epiphytes, and hemi‐epiphytes were more abundant in old‐fields. Herbaceous plants appeared as important components of the community in all habitats. The removal of low vegetation increased total plant recruitment in all habitats. Considering each growth form, the absence of vegetation increased recruitment in primary forests for herbs, in secondary forests for epiphytes and hemi‐epiphytes, in old‐fields for trees, and for lianas in primary forests and old‐fields. In vegetation removal plots, recruitment of species was greater in pastures, lower in secondary forest, and similar in primary forest with respect to control plots. Depending on habitat type, species, and growth form, the presence of low vegetation may act as a recruitment barrier or facilitator for different species, affecting plant community structure, diversity, and composition in different habitats. 相似文献
10.
The amount of carbon released to the atmosphere as a result of deforestation is determined, in part, by the amount of carbon held in the biomass of the forests converted to other uses. Uncertainty in forest biomass is responsible for much of the uncertainty in current estimates of the flux of carbon from land‐use change. In the present contribution several estimates of forest biomass are compared for the Brazilian Amazon, based on spatial interpolations of direct measurements, relationships to climatic variables, and remote sensing data. Three questions were posed: First, do the methods yield similar estimates? Second, do they yield similar spatial patterns of distribution of biomass? And, third, what factors need most attention if we are to predict more accurately the distribution of forest biomass over large areas? The answer to the first two questions is that estimates of biomass for Brazil's Amazonian forests (including dead and belowground biomass) vary by more than a factor of two, from a low of 39 PgC to a high of 93 PgC. Furthermore, the estimates disagree as to the regions of high and low biomass. The lack of agreement among estimates confirms the need for reliable determination of aboveground biomass over large areas. Potential methods include direct measurement of biomass through forest inventories with improved allometric regression equations, dynamic modelling of forest recovery following observed stand‐replacing disturbances, and estimation of aboveground biomass from airborne or satellite‐based instruments sensitive to the vertical structure plant canopies. 相似文献
11.
Abstract In the 2005 edition of the Global Forest Resources Assessment of the Food and Agriculture Organization of the United Nations, a moderate negative trend was reported regarding the change of tropical forests: the net annual change was estimated at ?11.8 million ha for the period 2000–2005, while the rate was ?11.65 for the previous decade. Tropical Asia showed the highest rate and most negative trend, passing from ?0.8% to ?0.96% per year. The remote sensing survey done for previous Forest Resource Assessment editions covering the period 1980–2000 revealed distinct change processes in the three tropical regions. Survey results indicated that socio‐economic and cultural aspects that characterise and differentiate the geographic regions determine the nature of the change processes and underlying cause–effect mechanisms, while the ecological setting determines the intensity of change and reveals its environmental implications. A comparison of deforestation processes of the two decades indicated an on‐going process of “radicalisation” of the dynamics determined by an increasing frequency of high‐gradient changes (e.g. total clearing rather than fragmentation and degradation) and by a shift of deforestation fronts towards wetter zones, with a consequent higher per‐hectare carbon emission associated with deforested areas. 相似文献
12.
Peter Groenendijk Peter van der Sleen Mart Vlam Sarayudh Bunyavejchewin Frans Bongers Pieter A. Zuidema 《Global Change Biology》2015,21(10):3762-3776
The important role of tropical forests in the global carbon cycle makes it imperative to assess changes in their carbon dynamics for accurate projections of future climate–vegetation feedbacks. Forest monitoring studies conducted over the past decades have found evidence for both increasing and decreasing growth rates of tropical forest trees. The limited duration of these studies restrained analyses to decadal scales, and it is still unclear whether growth changes occurred over longer time scales, as would be expected if CO2‐fertilization stimulated tree growth. Furthermore, studies have so far dealt with changes in biomass gain at forest‐stand level, but insights into species‐specific growth changes – that ultimately determine community‐level responses – are lacking. Here, we analyse species‐specific growth changes on a centennial scale, using growth data from tree‐ring analysis for 13 tree species (~1300 trees), from three sites distributed across the tropics. We used an established (regional curve standardization) and a new (size‐class isolation) growth‐trend detection method and explicitly assessed the influence of biases on the trend detection. In addition, we assessed whether aggregated trends were present within and across study sites. We found evidence for decreasing growth rates over time for 8–10 species, whereas increases were noted for two species and one showed no trend. Additionally, we found evidence for weak aggregated growth decreases at the site in Thailand and when analysing all sites simultaneously. The observed growth reductions suggest deteriorating growth conditions, perhaps due to warming. However, other causes cannot be excluded, such as recovery from large‐scale disturbances or changing forest dynamics. Our findings contrast growth patterns that would be expected if elevated CO2 would stimulate tree growth. These results suggest that commonly assumed growth increases of tropical forests may not occur, which could lead to erroneous predictions of carbon dynamics of tropical forest under climate change. 相似文献
13.
Christopher W. Dick Simon L. Lewis Mark Maslin Eldredge Bermingham 《Ecology and evolution》2013,3(1):162-169
Tropical rain forest has been a persistent feature in South America for at least 55 million years. The future of the contemporary Amazon forest is uncertain, however, as the region is entering conditions with no past analogue, combining rapidly increasing air temperatures, high atmospheric carbon dioxide concentrations, possible extreme droughts, and extensive removal and modification by humans. Given the long‐term Cenozoic cooling trend, it is unknown whether Amazon forests can tolerate air temperature increases, with suggestions that lowland forests lack warm‐adapted taxa, leading to inevitable species losses. In response to this uncertainty, we posit a simple hypothesis: the older the age of a species prior to the Pleistocene, the warmer the climate it has previously survived, with Pliocene (2.6–5 Ma) and late‐Miocene (8–10 Ma) air temperature across Amazonia being similar to 2100 temperature projections under low and high carbon emission scenarios, respectively. Using comparative phylogeographic analyses, we show that 9 of 12 widespread Amazon tree species have Pliocene or earlier lineages (>2.6 Ma), with seven dating from the Miocene (>5.6 Ma) and three >8 Ma. The remarkably old age of these species suggest that Amazon forests passed through warmth similar to 2100 levels and that, in the absence of other major environmental changes, near‐term high temperature‐induced mass species extinction is unlikely. 相似文献
14.
15.
Humans have altered global and regional cycles of nitrogen (N) more than any other elements. Increasing N emissions to the atmosphere from accelerating industrialization and production and use of fertilizer N now make N deposition significant not only in densely populated regions of Europe and North America, but also in other parts of the world (e.g., Asia and Latin America). Increased atmospheric N deposition is known to be able to reduce biodiversity in natural and semi-natural ecosystems. It is suggested that N deposition will be the third greatest driver of biodiversity loss on the global scale in this century, after land use and climate change. Based on published study results, we reviewed the impacts of N deposition on forest biodiversity by emphasizing 3 aspects: (1) plant diversity, including arborous plants, understory plants and cryptogam plants; (2) soil microorganism diversity; (3) animal diversity, including underground soil fauna and aboveground herbivores. In general, it was found that N deposition could alter species diversity, and excessive N could reduce species diversity, such as richness and abundance, and even lose special species. We also identified specific mechanisms on how excessive N deposition affected forest biodiversity. Finally, we summarized the current status of research on N deposition in China and in other countries, and proposed potential research activities and recommendations. 相似文献
16.
David C. Marvin Klaus Winter Robyn J. Burnham Stefan A. Schnitzer 《Global Change Biology》2015,21(5):2055-2069
Recent studies indicate that lianas are increasing in size and abundance relative to trees in neotropical forests. As a result, forest dynamics and carbon balance may be altered through liana‐induced suppression of tree growth and increases in tree mortality. Increasing atmospheric CO2 is hypothesized to be responsible for the increase in neotropical lianas, yet no study has directly compared the relative response of tropical lianas and trees to elevated CO2. We explicitly tested whether tropical lianas had a larger response to elevated CO2 than co‐occurring tropical trees and whether seasonal drought alters the response of either growth form. In two experiments conducted in central Panama, one spanning both wet and dry seasons and one restricted to the dry season, we grew liana (n = 12) and tree (n = 10) species in open‐top growth chambers maintained at ambient or twice‐ambient CO2 levels. Seedlings of eight individuals (four lianas, four trees) were grown in the ground in each chamber for at least 3 months during each season. We found that both liana and tree seedlings had a significant and positive response to elevated CO2 (in biomass, leaf area, leaf mass per area, and photosynthesis), but that the relative response to elevated CO2 for all variables was not significantly greater for lianas than trees regardless of the season. The lack of differences in the relative response between growth forms does not support the hypothesis that elevated CO2 is responsible for increasing liana size and abundance across the neotropics. 相似文献
17.
RITA GRIES JULIO LOUZADA SABRINA ALMEIDA RENAN MACEDO JOS BARLOW 《Insect Conservation and Diversity》2012,5(3):175-185
Abstract. 1. Although plantation forests are being established at an increasing rate, their effects on biodiversity are still debated. 2. Native candeias [Eremanthus erythropappus (DC.) Mac Leish] and exotic eucalyptus (Eucalyptus spp.) have recently been planted on Cerrado grasslands. The Cerrado is the second largest biome of Brazil and one of the most threatened savanna ecosystems. 3. Here, we use dung beetles (Scarabaeinae) to investigate the effects of the land‐use changes associated to afforestation on Cerrado insect biodiversity. We sampled dung beetles in candeia (4‐ and 6‐year‐old) and eucalyptus plantations (1‐ and 4‐year‐old), natural candeia formations (candeiais), native grasslands and natural forests. 4. Dung beetle diversity in plantations was lower than in grasslands and forests, but was not different from diversity in natural candeiais. Candeia and 1‐year‐old eucalyptus plantations, grasslands and natural candeiais all had similar community composition, distinct from natural forests. Four‐year‐old eucalyptus plantations were intermediate between those two groups. Overall, afforestation was detrimental for dung beetles. 5. Differences between exotic and native plantations were only apparent in older plantations, and seemed to be due to differences associated to canopy openness rather than to the origin of the planted species. Candeia plantations were of better conservation value for open‐area species (62% species shared between grasslands and candeia plantation) whereas eucalyptus plantations were so for forest species (26% species shared between forests and eucalyptus plantations). We recommend considering this result before deciding where to plant which species. 相似文献
18.
The impacts of climate change on forest net biomass change are poorly understood but critical for predicting forest's contribution to the global carbon cycle. Recent studies show climate change‐associated net biomass declines in mature forest plots. The representativeness of these plots for regional forests, however, remains uncertain because we lack an assessment of whether climate change impacts differ with forest age. Using data from plots of varying ages from 17 to 210 years, monitored from 1958 to 2011 in western Canada, we found that climate change has little effect on net biomass change in forests ≤ 40 years of age due to increased growth offsetting increased mortality, but has led to large decreases in older forests due to increased mortality accompanying little growth gain. Our analysis highlights the need to incorporate forest age profiles in examining past and projecting future forest responses to climate change. 相似文献
19.
Sabine Both Dafydd M. O. Elias Ully H. Kritzler Nick J. Ostle David Johnson 《Ecology and evolution》2017,7(22):9307-9318
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