Respiratory Parameters Define Growth Rate,Species Distribution and Adaptation to Temperature

Abstract

Agricultural expansion by smallholder producers has been identified by management agencies as one of the main threats to the ecological integrity of La Amistad Biosphere Reserve, in Panama and Costa Rica. Promotion of cacao agroforestry has been proposed as a way to reduce the need for farmers to clear new land within the reserve. In order to realize this goal, the larger cultural, economic, and political forces that motivate agricultural expansion need to be examined, looking beyond the smallholder practices that are the immediately apparent causes of ecological degradation. The four main assumptions behind the proposal to promote smallholder cacao production in the buffer zone are explored: (1) cacao agroforestry is an ecologically benign agricultural system; (2) if cacao production were more financially viable, ecologically degrading activities, such as cattle grazing, would decrease; (3) migrants from other areas are primarily responsible for clearing land on the eastern side of the park; and (4) direct intervention at the smallholder level is the most effective means of preventing agricultural expansion. Our analysis demonstrates that while cacao agroforestry is an ecologically appropriate production system for the buffer zone of the park, price and production stabilization is important for assuring adoption by smallholders. We also suggest that both indigenous and migrant groups are responsible clearing forest for agriculture and that a more useful distinction for managers to make is between clearing enacted as part of sustainable vs. unsustainable management regimes. Finally, we recommend that the impact to the biosphere reserve caused by large-scale cattle and banana production not be overlooked.     

土地利用变化的遥感监测及其与经济发展关系的研究 --以增城市1998-2003土地利用为例

随着经济的发展，增城市的社会经济状况发生了巨大的变化，在这些变化中以土地变化最为显著，而土地利用的变化在经济发展、生态改变及土地可持续发展等方面都具有深刻的影响，尤其是对经济发展影响更加直接和显著。本文分析了增城市土地利用变化及其与经济发展的关系，通过遥感检测技术（post-classification）获取了增城市1998-2003年两年间的土地利用变化数据，并以此为基础进行了土地利用动态变化模型分析。结合社会统计数据探讨了土地利用变化与其经济发展的关系，同时深层次地分析了产生这种土地利用变化的驱动原因。     

Changes in Soil Aggregate-Associated Organic Carbon and Nitrogen after Ten Years under Different Land-Use and Soil-Management Systems in Indo-Gangetic Sodic Soil

A study was conducted to evaluate the effects of different land uses and soil-management systems (LU and SMS) on key soil physicochemical indicators [aggregate stability, distribution of soil organic carbon (SOC), and nitrogen (N) in aggregate fractions] and to interpret significance of long-term cultivation of agroforestry plantations [Prosopis juliflora L. (AFP) and Casuarina equisetifolia L. (AFC)], horticultural plantations [(Tamarindus indica (HI) and Syzygium cumini (HJ)], and rice–wheat system (RW) in sodic soil of the Indo-Gangetic plain. Soil samples collected from the different LU and SMS plots were analyzed. The barren sodic soil (BSS) exhibited the least mean weight aggregate diameter (0.21), whereas AFP recorded the greatest (0.59). Total N content in surface soil under RW system was about the same as AFP, AFC, HI, and HJ and significantly greater than BSS. Across the LU and SMS except BSS, microaggregates recorded a narrower C/N ratio than macro- and mesoaggregates.     

Effect of Land-Use History on Soil Carbon and Nitrogen in a Mediterranean Catchment

The impact of land use on soil organic matter was investigated. Five land cover types (pine forest, olive groves, wheat, wheat/maize cultivation systems, and a shrub pasture) belonging to three land-use categories from the same catchment in the island of Lesvos, Greece, were used. The soils developed under similar pedogenetic processes and accepted similar agricultural practices for at least 30 years. The results showed that the land-use and cover types ranged according to their total soil carbon (C) content as follows: forest > double cultivation > wheat > olive > pasture. Crop plantations contained 31 to 40% less C at their upper 0- to 45-cm layer than forest. Pasture had shallow soils with a small C accumulation but high C concentration, whereas olive groves had the lowest concentrations of both soil C and nitrogen (N). Olive grove soils were the most prone to degradation but possessed the greatest potential for C sequestration.     

基于土地利用的北方农牧交错区碳固定和土壤保持时空变化

为探讨农牧交错区土地利用变化及其对生态系统服务的影响,以内蒙古达茂旗为研究区,通过土地利用转移矩阵和变化动态度的计量,采用模型模拟生态系统服务碳固定、土壤保持功能的方法,分析2000—2015年该旗碳固定和土壤保持演变特征。结果表明：草地、未利用地和耕地是主要的土地利用类型,16年间,草地、建设用地、未利用地、林地面积明显增加,耕地面积显著减少。土地利用类型变化主要是从耕地向草地、从草地向建设用地转移。2000—2015年,全旗碳固定量从183.25万t减少到181.65万t,土壤保持量从170.58万t减少到107.32万t,这一变化主要是由于研究区草地质量的降低使得单位面积提供的生态系统服务减少。各土地利用类型提供的碳固定和土壤保持均表现为草地 > 耕地 > 未利用地 > 建设用地 > 灌木林 > 林地 > 盐碱地 > 水域 > 沙漠。综上,在今后的生态治理中,应考虑在扩大草地面积、保护农田的基础上,适度利用草地、农田等生产生活用地,提高草地质量,科学优化土地利用结构,保障生态系统良性演化,提高生态系统服务功能。     

叠加分类及其在冀太行山区土地利用类型遥感解译中的应用

计算机遥感解译方法主要包括监督分类和非监督分类2种，但两者均具有一定局限性。为了更精确地获取土地利用类型信息，在分别采用监督分类与非监督分类的基础上，提出了叠加分类的遥感解译方法。此方法的关键在于，叠加分类时对叠加图像进行部分重新编码，即只对监督分类与非监督分类中的典型地物进行重新编码，这样会使监督分类图与非监督分类图进行较为充分的叠加，叠加后再进行重新编码，以保证良好的分类效果。以河北省太行山区为对象进行了案例研究，对监督分类、非监督分类和叠加分类进行了比较分析。研究结果表明，叠加分类效果最好，具有操作简单，人为影响较小，精度较高等优点。图3表3参17     

Quantification of land-use dynamics: An illustration from Costa Rica

In many cases, studies dealing with land degradation require the quantification of land-use dynamics. Although research has been carried out to describe land-use dynamics and its driving forces, very little has been done on the recognition of indicators for the quantification of land-use dynamics. This article presents and discusses three different indicators recognised during a Costa Rican case-study: (1) a single-time analysis of spatial patterns; (2) standard Markov chains with a soil-type modifier; (3) geo-referenced Markov chains with indices for size, shape and land cover in neighbouring polygons. The first indicator is applied to a study area of 2942 km² in the northeast of Costa Rica for which 1992 aerial photographs are available. Spatial patterns of land cover can only be related to land cover modifications when good insight into the colonization history exists. For the study area, clear land-use sequences have been found. Both standard and geo-referenced Markov chains have been calculated for a smaller pilot area of 151 km² for which aerial photographs taken on five different dates area available. Clear differences in probabilities are found for soil type and polygon size. For the shape and boundary index, no clear relations were found in the pilot area. The quantification of land-use dynamics using these kinds of indicators is necessary for the comparison of regions and for land degradation modelling.     

An approach to land-use planning in a hilly watershed using geographical information system

The eco-socio-economic balance of a region can be preserved by proper land-use planning, particularly in hilly watersheds where erosion caused by rainfall is an ever-present threat. This paper describes a methodology developed to compile a treatment-oriented land-use planning scheme for a hilly watershed using a geographical information system (GIS). A remote sensing based physiographic soils map and a digital elevation model (DEM) are the sources of soil depth and slope steepness classes, respectively, and are the information databases for GIS analysis. The GIS was used to integrate these databases and provide tools for manipulation of the data. A set of knowledge-based rules was formed from the classification scheme formulated by Sheng and Stennett (1975) for hilly watersheds, modified to allow for the local land-use patterns. These rules were used to manipulate the databases and allow the establishment of a sustained land-use system in the watershed with proper soil and water conservation measures. This biological engineering scheme would be a safeguard against soil erosion and other environmental threats. A priority sub-watersheds delineation survey conducted in the watershed indicates significant variation in the silt yield index values, which calls for conservation planning in earnest in cases of high and very high priority sub-watersheds.