土地利用变化对昆明生态服务功能的影响

利用昆明市三期土地利用数据，分析了昆明市快速城市化过程中土地利用变化，并计算由此导致的生态系统服务价值变化。并得出如下结论：1992年至2000年、2000年至2004年两个阶段内林地和城市用地的面积不断增加，而灌草地、耕地和水域的面积不断减少；1992年昆明市总的生态系统服务功能有所增加，而其中林地在历年的生态系统服务功能中所占的比例具有绝对优势，并且呈递增趋势；2000年至2004年间生态服务功能的年变化量要普遍大于1992年至2000年间的年变化量，这是因为土地利用变化在后一阶段更加剧烈。     

Diversity and composition of tropical secondary forests recovering from large-scale clearing: results from the 1990 inventory in Puerto Rico

The extensive recovery from agricultural clearing of Puerto Rican forests over the past half-century provides a good opportunity to study tropical forest recovery on a landscape scale. Using ordination and regression techniques, we analyzed forest inventory data from across Puerto Rico’s moist and wet secondary forests to evaluate their species composition and whether the landscape structure of older forest affected tree species composition of recovering forests at this scale. Our results support conclusions from studies conducted in Puerto Rico at smaller scales and temperate forests at larger scales that timing of abandonment and land use history are of overwhelming importance in determining the species composition of recovering forests. Forest recovery is recent enough in Puerto Rico that previous land use is clearly evident in current species composition, and creates new forest communities. As demonstrated in other work, physical factors such as elevation and substrate co-vary with land use history, so that the species composition of the forest landscape results from the interplay between biophysical and socioeconomic forces over time. Our results also indicate that increasing the distance to the largest forest patches occurring in the landscape 12 years previous had a small negative impact on species richness but not species diversity or community composition. We conclude that land use history has as much influence in species composition as biophysical variables and that, at the scale of this study, there is no large influence of forest landscape structure on species diversity or composition.     

Protection vs. commercial management: Spatial and temporal analysis of land cover changes in the tropical forests of Central India

Tropical forests worldwide are undergoing rapid changes due to increasing human populations and varied land use practices. In an effort to protect these forests and their species, the number of protected areas has increased exponentially in recent decades. Clearly protected areas play a crucial role in conservation efforts and this strategy has been found to be successful in several studies. However, protected areas are often embedded within a matrix of other land cover types, including non-protected forests, agricultural fields, or urban areas. It is therefore critical for park management to think beyond the borders of their protected areas and work to maintain ecological integrity of the surrounding matrix and the connectivity between protected areas. This study integrates remote sensing, GIS and field observations to examine the effects of different management strategies on land cover changes. As a case study we examine a tiger reserve in Central India which is surrounded by commercially managed forests, representative of many protected areas throughout India. Findings of this study show that while protected areas play an important role in conservation, alternative approaches including favorable management policies could also be effective to extend conservation over larger areas.     

Land use change and net C flux in Indian forests

This paper reports on the net carbon flux caused by deforestation and afforestation in India over the period from 1982 to 2002, separately for two time periods, 1982–1992 (PI) and 1992–2002 (PII), using the IPCC 2006 guidelines for greenhouse gas inventories. The approach accounts for forest and soil C pool changes for (a) forest areas remaining as forests, (b) afforested areas and (c) deforested areas. The data set used were remote sensing based forest cover for three time periods (1982, 1992, 2002), biomass increments, biomass expansion factors and wood density. In addition a number of required coefficients and parameters from published literature were adopted. In the 1982–2002 period, the forest cover changed from 64.20 Mha in 1982 to 63.96 and 67.83 Mha in 1992 and 2002 respectively. During the PI and PII periods, plantations were also established of 0.2 and 0.5 Mha yr⁻¹, while the annual deforestation rate was about 0.22 and 0.07 Mha in these periods, respectively.     

Comparison of temporal and spatial changes in three major tropical forests based on MODIS data

Numerous studies have shown that intact tropical forests account for half of the total terrestrial sink for anthropogenic carbon dioxide.Here,we analyzed and compared changes in three main tropical forest regions from 2000 to 2014,based on time-series analysis and landscape metrics derived from moderate-resolution imaging spectroradiometer data.We examined spatialpattern changes in percentage of tree cover and net primary production(NPP)for three tropical forest regions—Amazon basin,Congo basin,and Southeast Asia.The results show that:the Amazon basin region had the largest tropical forest area and total NPP and a better continuity of TC distribution;the Southeast Asia region exhibited a sharp decrease in NPP and had comparatively separate spatial patterns of both TC and NPP;and the Congo basin region exhibited a dramatic increase in NPP and had better aggregation of forest NPP distribution.Results also show that aggregative patterns likely correlate with high NPP values.     

Assessment of ecosystem services as an opportunity for the conservation and management of native forests in Chile

This paper quantifies two important native forest ecosystem services in southern Chile: water supply and recreational fishing opportunities. We analyzed streamflow in relation to forest cover in six watersheds located in the Valdivian Coastal Range (39°50′–40°05′S), the effect of forest management on streamflow in two watersheds in the Valdivian Andes (600–650 m of elevation; 39°37′S), and fish abundance as a function of forest cover in 17 watersheds located in the Coastal Range and the Central Depression (39°50′–42°30′S). We found that the annual direct runoff coefficient (quickflow/precipitation) and total streamflow/precipitation in the dry summer season were positively correlated with native forest cover in the watershed (R² = 0.67 and 0.76; ^*P = 0.045 and 0.027, respectively) during four years of observations. Conversely, a negative correlation was found between summer runoff coefficients (total streamflow/precipitation) and cover of Eucalyptus spp. and Pinusradiata plantations (R² = 0.84; ^*P = 0.010). We estimated a mean increase of 14.1% in total summer streamflow for every 10% increase in native forest cover in the watershed. The analysis of streamflow changes between two paired watersheds dominated by native secondary Nothofagus stands, one thinned with 35% of basal area removal and a control, showed that the former had a 40% increase during summer (four years of observations). The best correlation between fish abundance and forest cover was found between trout abundance (%) and secondary native forest area in 1000 m × 60 m stream buffers (R² = 0.65, ^***P < 0.0001). We estimated a 14.6% increase in trout abundance for every 10% increase of native forest cover in these buffers. Similar approaches to quantify forest ecosystem services could be used elsewhere and provide useful information for policy and decision-making regarding forest conservation and management.     

岷江上游地区土地利用变化及潜在生态服务价值评估

为了定量分析岷江上游地区生态系统服务功能及其价值变化,运用遥感、地理信息系统和一系列数学方法对其评估,为更好的管理生态系统提供合理化建议.结果表明：土地利用转换主要发生在森林,农田和草地之间.从1986年到1994年,农田面积增加了60801hm^2,比1986年增长了477%;林地面积减少了89012.17hm^2,占原有面积的4.97%.人口增长和森林砍伐降低了森林生态系统服务价值,相应地农田生态系统服务价值升高.生态系统总的服务价值从1986年到2000年减少了771.11亿元.本文还探讨了生态系统服务价值变化的驱动力,其中国家政策在生态系统服务功能保护上起到了一定的作用.     

The ecology and ecosystem services of native trees: Implications for reforestation and land restoration in Mesoamerica

Tropical forests provide a variety of goods and services to humanity. Although efforts to protect and manage these forests have increased in recent decades, forest loss continues. The last decade and a half has seen considerable research on reforestation with native species in Mesoamerica, including both biophysical and social aspects. Advances in knowledge have led to increasingly sophisticated reforestation treatments as well as novel ways of deriving forest goods and services from human dominated landscapes.This Special Issue includes articles produced as the result of a conference held in Panama City, Panama in January 2010 with the goal to summarize the state of knowledge of native species reforestation and associated ecosystems services in Mesoamerica. The introduction concludes with a call for continued research, including a mechanistic understanding of tree interactions with the biophysical environment in order to advance or knowledge of ecosystem services and their interactions. Results from these and other studies aimed at socioeconomic aspects of reforestation are critical to land use planning.     

Ecology and regeneration of tropical dry forests in the Americas: Implications for management

Dry forests represent the most endangered ecosystem in tropical regions and continue to be one of the most sought after environments for human colonization, development and production. In spite of this, dry forests are one of the least well studied tropical habitats. This special issue is dedicated to reviewing much of the information that exists about tropical dry forest in the Americas. The introduction summarizes the articles presented herein, highlighting management strategies that are suggested throughout the special issue that may be useful for conserving tropical dry forest environments.     

Variation in vegetation structure and soil properties related to land use history of old-growth and secondary tropical dry forests in northwestern Mexico

The objective of this study was to compare the vegetation structure and soil properties among old-growth tropical dry forests representing three categories of grazing intensity by cattle (light, moderate and heavy grazing) and a category of 20–30-yr-old secondary forest experiencing occasional grazing in a locality in northwestern Mexico. Within each forest type, three 0.1 ha plots located in different grazing ranges (“potreros”) were used as replicates. All woody plants (stem ≥ 2.0 cm diameter at 1.30 m height, DBH) were identified and measured in each plot. Mean basal area and above-ground biomass (AGB) were significantly higher in the moderately grazed old-growth forest. Species density was significantly lower in the secondary forest, where a leguminous tree species was dominant. Accumulation of AGB after 20–30 yr of secondary forest recovery accounted for 43% of the old-growth forest AGB. Soil properties varied among forest categories but did not follow a consistent pattern: mean total N and organic matter content were highest in the old-growth forest with moderate grazing; cation exchange capacity (CEC) was similar among the three old-growth forests categories, but it was significantly lower in the secondary forest compared to the old-growth forest with low grazing. Canonical Correspondence Analysis showed that CEC was highly correlated with the actual species distribution in the study area, especially with Acacia cochliacantha the dominant species of the secondary forest category. Resprouting capacity of the persisting species in the old-growth forests experiencing chronic disturbance could have contributed to the maintenance of some of the structural characteristics of a mature forest. Tropical secondary forests seem to accumulate AGB relatively fast, reflecting their potential for carbon storage and provision for other ecosystem services; therefore, they deserve urgent protection measures.     

Early seedling establishment of two tropical montane cloud forest tree species: The role of native and exotic grasses

Tropical montane cloud forest has been undergoing a drastic reduction because of its widespread conversion to pastures. Once these forests have been cleared exotic grasses are deliberately introduced for forage production. Exotic grass species commonly form monodominant stands and produce more biomass than native grass species, resulting in the inhibition of secondary succession and tree regeneration. The purpose of this study was to assess the effect of native vs. exotic grass species on the early establishment of two native tree seedlings (Mexican alder, Alnus acuminata and Jalapa oak, Quercus xalapensis) on an abandoned farm in central Veracruz, Mexico. Seedling survival and growth were monitored (over 46 weeks) in relation to grass cover and height, and available photosynthetic active radiation (PAR). More seedlings survived in the presence of the native grass Panicum glutinosum than those growing with the exotic grass Cynodon plectostachyus (92% vs. 48%). The causes of seedling mortality varied between species; Q. xalapensis was affected by herbivory by voles but mainly in the exotic grass-dominated stands, whereas A. acuminata seedlings died due to competition with the exotic grass. A. acuminata seedlings increased more in height in the exotic grass-dominated stands (102 ± 7.8 cm) compared to native grass-dominated stands (51 ± 4.7 cm). Grass layer height, cover and available PAR were correlated (Pearson; p < 0.05). In the exotic grass dominated plots, grass layer height was correlated with the relative height growth rates of Q. xalapensis (Pearson; p < 0.05). These results indicate that the exotic grass may be affecting tree regeneration directly (grass competition) and indirectly (higher herbivory). Passive restoration may occur once P. glutinosum dominated pastures are abandoned. However, when C. plectostachyus dominates, introduction of early and mid successional tree seedlings protected against vole damage is needed.     

Recovery of saturated hydraulic conductivity under secondary succession on former pasture in the humid tropics

Landscapes in the humid tropics are undergoing a continuous change in land use. Deforestation is still taking its toll on forested areas, but at the same time more and more secondary forests emerge where formerly agricultural lands and pastures are being abandoned. Regarding soil hydrology, the extent to which secondary succession can recover soil hydrological properties disturbed by antecedent deforestation and pasture use is yet poorly understood. We investigated the effect of secondary succession on saturated hydraulic conductivity (Ks) at two soil depths (0-6 and 6-12 cm) using a space-for-time approach in a landscape mosaic in central Panama. The following four land-use classes were studied: pasture (P), secondary forest of 5-8 years of age (SF5), secondary forest of 12-15 years of age (SF12) and secondary forest of more than 100 years of age (SF100), each replicated altogether four times in different micro-catchments across the study region. The hydrological implications of differences in Ks in response to land-use change with land use, especially regarding overland flow generation, were assessed via comparisons with rainfall intensities.Recovery of Ks could be detected in the 0-6 cm depth after 12 years of secondary succession: P and SF5 held similar Ks values, but differed significantly (α = 0.05) from SF12 and SF100 which in turn were indistinguishable. Variability within the land cover classes was large but, due to sufficient replication in the study, Ks recovery could be detected nonetheless. Ks in the 6-12 cm depth did not show any differences between the land cover classes; only Ks of the uppermost soil layer was affected by land-use changes. Overland flow - as inferred from comparisons of Ks with rainfall intensities - is more likely on P and SF5 sites compared to SF12 and SF100 for the upper sample depth; however, generally low values at the 6-12 cm depth are likely to impede vertical percolation during high rainfall intensities regardless of land use.We conclude that Ks can recover from pasture use under secondary succession up to pre-pasture levels, but the process may take more than 8 years. In order to gain comprehensive understanding of Ks change with land use and its hydrological implications, more studies with detailed land-use histories and combined measurements of Ks, overland flow, precipitation and throughfall are essential.     

Changes of forest land use and ecosystem service values along Lao-Chinese border: A case study of Luang Namtha Province, Lao PDR

Forest cover and land use change directly impact biological diversity worldwide, contribute to climate change and affect the ability of biological systems to support human needs by altering ecosystem services. Given the forest land use characteristics and ecosystem types in Luang Namtha Province, Lao PDR, the forest cover and land cover category of Luang Namtha Province were divided into six classes, i.e., current forest (CF), potential forest (PF), other wooded areas (OW), permanent agricultural land (PA), other non-forest areas (NF) and water (W). In first instance, earlier geographic information data (GIS data) of forest cover and land use during 1992 and 2002 was obtained from the Ministry of Agriculture and Forestry (MAF), Lao PDR. Two steps of forest land use change assessment were conducted by the MAF, i.e., plot sampling on satellite image maps (SIMs) to detect the changes of forest cover and land use during 1992 and 2002 for the entire Luang Namtha Province and field verification in order to identify causes of the changes. Secondly, dynamic information of the forest land cover changes during this ten-year period was calculated by means of map algebra in ArcGIS 9.2. Thirdly, based on the theory of ecosystem service functions and the service function values of different global ecosystems, the value of the six forest cover and land use categories in the province was obtained. Finally, ecological environmental effects, produced by the regional land cover changes over the study period, were calculated.     

Exploring the effect of changes in land use on soil quality on the eastern slope of the Cofre de Perote Volcano (Mexico)

Changes in land use on the eastern slope of the Cofre de Perote Volcano (Mexico) appear to have a negative effect on soil quality. In this study, we use a multivariate data set to research whether the change in land use has affected soil quality and to identify the indicators that best represent variability of the original data set. An elevation transect was identified as follows: upper segment (US), middle segment (MS) and lower segment (LS). The following nondisturbed areas and farm fields were sampled: US: pinus forest (PF), corn cropland (CP), and abandoned cropland (AC); MS: tropical cloud forest (TF), corn cropland (CC), and grassland (GL); LS: oak forest (OF) and sugarcane (SG). Sixteen soil chemical, physical, and biological attributes were measured on each site of interest. It was shown that the change in land use caused a reduction in organic material content, especially on MS and LS. The highest acidity was recorded in nondisturbed soils and abandoned cropland. Microbial biomass-C (C_m) and the microbial quotient (C_m/C) were altered the most on MS and LS. C_m and mineralized N (Nm) decreased from US to LS. Bulk density (BD) increased with the change in land use, especially on LS. Principal component analysis was used to analyze soil quality overall. The first principal component (PC1) explained 46% of the total variance of the data set, and seven soil attributes had significant loadings. C, N, and total porosity (TP) were negatively weighted and were contrasted with Mg, ECEC, BD, and C_m/C. The second principal component (PC2) explained 16% and had significant positive loadings on Ca, inorganic nitrogen (Ni), and C_m. LS soils had the highest PC1 scores and US soils the lowest. The positively high PC1 scores recorded for LS soils revealed a greater sensitivity to changes in land use. In US, there were no significant effects on PC1 caused by land use change, while in the MS, positively high PC1 scores obtained in the CC soil were related to greater microbial activity and a decrease in C and N. In LS, SG soil had significantly higher PC1 scores than OF soil, indicating an increase in microbial activity.     

Ecosystem services of fast-growing tree plantations: A case study on integrating social valuations with land-use changes in Uruguay

The rapidly increasing area of tree plantations, especially in the tropics and subtropics, has raised expectations and concerns as to their impact on ecosystem services. We studied the effect of the establishment of eucalyptus and pine plantations on local people's social valuations of ecosystem services in a case study in Uruguay. We also assessed the social and political restrictions that might limit the establishment of new markets for ecosystem services. Our study showed that the rapid change in land use in Uruguay over the past 20 years, from grassland to plantations, has affected people's perceptions of landscape's capacity to produce ecosystem services. The ecosystem services of plantations that showed the greatest discrepancy between local people's valuations and both recognition by experts and current scientific evidence were biodiversity, water effects, and carbon cycling. We found that in particular regulating services, and some provisioning ones, are quite well recognized by substance specialists, but are sometimes rather unfamiliar to the general public. The proper planning of plantations may improve the provision of ecosystem services, such as biodiversity enhancement, wood availability for fire and energy, water quality, and carbon sequestration, while at the same time diluting some others. The selection of ecosystem services to be taken into account in plantation management depends both on local cultural values and on the particular environmental pressures considered to be most in need of mitigation.     

Effects of legal regulations on land use change: 2/B applications in Turkish forest law

For the countries struggling with climate change, sustainable forestry is one of the greatest challenges and is difficult to define, implement, and to measure. According to the scientific community’s consensus on climate change, forests are one of the major sinks and sustainable forest management (SFM) is needed to prevent deforestation and its negative effects on natural ecosystems. Despite being a party to many international treaties/agreements related to land use policies (LUP) that are promoting SFM to protect and develop forest resources, the 2/B application in Turkish forest legislation has been causing deforestation in Turkey since the 1970s.

In this study, 2/B applications–political and legal process–causing deforestation by land use change (LUC) are investigated by carrying out a legal analysis. About 500.000 ha of forests have been lost due to the 2/B application and as a LUP directly affects SFM, carbon sequestration capacities (CSC), and therefore, climate change. To exemplify this pre and post-LUC change and effect, the amount of carbon that was prevented from being absorbed as 176,7 tonnes/ha on average in a given forest area for the year 2016. There is a vital need to address the negative effects of ill-defined forest legislation to achieve SFM.     

National assessment of the fragmentation, accessibility and anthropogenic pressure on the forests in Mexico

Forest managers and policy makers increasingly demand to have access to estimates of forest fragmentation,human accessibility to forest areas and levels of anthropogenic pressure on the remaining forests to integrate them into monitoring systems,management and conservation plans.Forest fragmentation is defined as the breaking up of a forest unit,where the number of patches and the amount of expose edge increase while the amount of core area decreases.Forest fragmentation studies in Mexico have been limited to local or regional levels and have concentrated only on specific forest types.This paper presents an assessment of the fragmentation of all forest types at the national level,their effective proximity to anthropogenic influences,and the development of an indicator of anthropogenic pressure on the forests areas.Broadleaf forests,tropical evergreen forests and tropical dry deciduous forests show the greatest fragmentation.Almost half(47%) of the tropical forests are in close effective proximity to anthropogenic influences and only 12% of their area can be considered isolated from anthropogenic influences.The values for the temperate forests are 23% and 29% respectively.Anthropogenic pressure in the immediate vicinity of anthropogenic activities is much higher in the tropical forests(75 in a scale 0-100) than in the temperate forests(30).When considering these results jointly,the tropical forests,and more specifically,the tropical evergreen forests and tropical dry deciduous forests are under the greatest pressure and risks of degradation.     

Monitoring the effects of land use and cover changes on net primary production: A case study in China's Yongding River basin

Changing land uses and cover types influence vegetation composition and health, so understanding the effects of these changes on net primary production (NPP) provides an important tool for monitoring ecosystem responses to environmental change. Using remote-sensing images and precipitation, temperature, and total solar radiation data from 1978, 1987, 2000, and 2005, and a light utilization efficiency model, we studied the effects of changes in these parameters and land use and cover types on NPP in China's Yongding River basin. We determined the NDVI of vegetation in the basin, and used these results to estimate the NPP of vegetation in the basin and the influence of land use and cover type changes on NPP under two climate scenarios: one in which the precipitation and temperature of the previous period remain unchanged into the following period, that is, use the climate in 1978, 1987 and 2000 to analyze NPP data in 1987, 2000 and 2005 respectively, and another in which both parameters remain constant at their 1978 values throughout the study period. With the climate unchanged from the former period, NPP in 1987 decreased compared with the 1978 value by 20–50 gC/m², and then increased by more than 40 gC/m² in western and central parts of the basin from 1987 to 2000. From 2000 to 2005, NPP decreased in the northwestern, northern, and eastern parts of the basin. With climate unchanged from 1978 to 2005, NPP increased from 1987 to 2000 by from 10 to 30 gC/m² in most areas. From 2000 to 2005, some farmland in western and northwestern parts of the basin and some forest land were converted into grassland, decreasing NPP by 40–50 gC/m².     

Linking physical, economic and institutional constraints of land use change and forest conservation in the hills of Nepal

This paper analyses the changes in spatial patterns of agricultural land use during the period 1976–2000 along the altitudinal gradients in a watershed in Nepal. Land change patterns during this period were examined using information on land use derived from satellite images from 1976, 1990 and 2000. During the 24-year period from 1976 to 2000 agricultural land use increased by 35% at a cost of loss of forestland. Agricultural expansion was most conspicuous at higher elevations (1150–2000-m). About 36%, 18% and 6% of forestland was converted into agricultural activities from higher, middle and lower elevations respectively in the period from 1990 to 2000. Spatial distribution of living standard parameters, including farm family income and, food availability obtained from family surveys, shows a decreasing trend as the elevation increases whereas percentage of food bought shows an increasing trend. In this way it was found that, lost forest areas were smaller when located around high-income areas with good quality agricultural land and near an administrative centre as compared to areas located around low-income areas with low quality agricultural land and far from an administrative centre. Additionally, a regression model is constructed, to link the socioeconomic variables with the conversion of forestland into agricultural activities, breaking the study area into smaller zones. The spatial trajectories of these zones are then contrasted, paying particular attention to the socioeconomic conditions and institutional arrangements governing access to land resources. The study finds that while overall land change patterns in the region are largely explained by elevation and the socioeconomic conditions of people living adjacent to the forestland, more specifically, in sub-regional areas, trajectories reflect the signatures of institutions governing access to land. As sustainability of the watershed is dependent on forests, continued depletion of forest resources will result in poor economic returns from agriculture for local people together with loss of ecosystem services.     

Evaluation of native tree species for the rehabilitation of deforested areas in a Mexican cloud forest

Four native tree species (Liquidambar styraciflua, Juglans pyriformis, Podocarpus matudae, and Carpinus caroliniana) were evaluated for their suitability in rehabilitating degraded areas of Mexican cloud forest. Plant survival and growth in height and diameter were determined in three mixed-experimental plantations with different land use histories; their performance was compared with two on-farm plantations started by landowners for forest restoration. Nearby forest fragments were controls for soil compaction. An experimental plantation with remnant trees had the highest plant survival (82%), height, basal diameter and relative growth rate. The plantation with the steepest slope had high plant survival (63%) and growth. The plantation characterized by dominance of grasses and compacted soils had the lowest survival (22%) and growth. On-farm plantations had good establishment of planted trees (5–10 species planted), and facilitated the recruitment of 9–11 woody species. Carpinus and Liquidambar appear to be suitable species for reforestation in all these areas. Podocarpus grew relatively slowly, although it performed well in two experimental sites. Juglans had high survival (76%) under the stressful conditions of the most adverse site, and therefore may be useful for rehabilitation of degraded sites. Differences among species and sites strongly suggest that species success depends on plantation site quality.