Forestland prediction of China based on forest ecosystem services for the first half of 21st century

A new model was developed to predict forestland demand of China during the years of 2010-2050 in terms of the concept of forest ecosystem services. On the basis of the relationship between forest ecosystem services and classified forest management, we hypothesized that the ecological-forest provides ecological services, whereas commercial-forest supplies wood and timber production, and the influences of the growth of population, social-economic development target, forest management methods and the technology changes on forest resources were also taken into account. The prediction reveals that the demand of total forestland of China will be 244.8, 261.2 and 362.2 million ha by the year 2010, 2020 and 2050, respectively. The results demonstrated that China will be confronted with a shortage of forest resources, especially with lack of ecological-oriented forests, in the future. It is suggested that sustainable management of forest resources must be reinforced and more attention should be drown no enhancing the service function of forest ecosystem.

Soil erosion and soil properties in reclaimed forestland of loess hilly region

Based on data observed from 1989 to 1998 in the Ziwuling survey station, changes of soil erosion and soil physico-mechanical properties were studied after forestland reclamation. When the man-induced factors changed the eco-environment by reclaiming forestlands, the intensity of man-made soil erosion in reclaimed lands was 1,000 times more than that of natural erosion in forestlands. From the analysis of soil physical and mechanical properties, the clay content and physical clay content decreased 2.74% and 3.01% respectively, and the >0.25 mm water stable aggregate content decreased 58.7%, the soil unit weight increased and the soil shear strength decreased, all of which were easier to cause soil erosion. The results of the correlation analysis showed that the >0.25 mm water stable aggregate content was the greatest influencing factor on soil erosion, the partial correlated coefficient was 0.9728, and then were soil coarse grain and soil shear strength, the partial correlated coefficients being 0.8879 and 0.6020 respectively. The relationships between the >0.25 mm water stable aggregate content, the soil sheer strength and the soil erosion intensity were analyzed, which showed that the first and seventh years were the turning years of the soil erosion intensity after the forestland reclamation. The degenerative eroded soil and eco-environment formed the peculiar erosion environment, which aggravated the soil erosion rapidly.

South Carolina forestland owners’ willingness to accept compensations for carbon sequestration

Background: Carbon sequestration through recommended forest management practices is an ecosystem service that helps mitigate climate change and its impacts while generating carbon credits for forestland owners to sell in cap-and-trade programs. The California’s cap-and-trade program (California’s carbon market hereafter) allows forestland owners from any part of the contiguous United States to supply carbon credits to compliance entities. In this study, we estimate South Carolina (SC) private forestland owners’willingness to accept compensations to participate in the California’s carbon market using a contingent valuation method. Results: We estimate forestland owners’mean willingness to accept as$67 per acre per year. Our results reveal higher probability of participation of forestland owners with interests in preserving forest ecosystems than those who do not. Additionally, forestland owners who trust in information about climate change from scientists or government are willing to participate more than those who do not. Conclusions: Various factors hinder landowners’ability to participate in carbon markets. Forestland owners in SC consider legislative uncertainty and long-time commitment as the main barriers to participation in California’s carbon market. From this research, average forestland tenure in SC is 27 years, which is far less than the 100-year time commitment of the California’s carbon market. Of those who agreed to participate, choosing between adopting and not adopting any of the three main forest management practices in the California’s carbon market:28% are likely to adopt improved forest management (IFM) practices, 24% are likely to adopt reforestation due to understocked forestlands, and 14% are likely to adopt avoided conversion. In another development, the concept of aggregation has dominated discussions in the California’s carbon market of late. It is an advocacy to include small-scale forestlands in the California’s carbon market. To aggregate, different forestland owners will combine their forestlands to participate. We find that 79% of SC forestland owners are willing to aggregate to participate. However, this research is unable to determine how much total forestland is available in SC for carbon market. We recommend future research in the State on forestland owners’participation in carbon market should consider evaluating forestland availability.

ECO-ENVIRONMENT CHANGE AND SOIL EROSION PROCESS IN THE RECLAIMED FORESTLAND OF THE LOESS PLATEAU

Serious soil erosion has made the eco-environment fragile in the Loess Plateau. Based on the 10-year data observed from 1989 to 1998 in the Ziwuling Survey Station in loess hilly region, the eco-environment change and soil erosion process in reclaimed forestland were studied in this paper. The results showed that the intensity of man-made soil erosion caused by forestland reclamation was 1000 times more than that of the natural erosion. From the analysis of soil physical and mechanical properties, in the 10th year after forestland was reclaimed, the clay content and physical clay content decreased 2.74 percentage point and 3.01 percentage point respectively, the >0.25mm waterstable aggregate content decreased 31.59 percentage point, the soil bulk density increased and soil shear strength decreased, all of which were easier to cause soil erosion. The correlation analysis showed that >0.25mm waterstable aggregate content was the key factor affecting soil erosion, and the secondary factors were soil coarse grain and soil shear strength. The relation between the >0.25mm waterstable aggregate content, the soil sheer strength and the soil erosion intensity were analyzed, which showed that the first year and the seventh erosion year were the turn years of the soil erosion intensity after the forestland was reclaimed, revealed that the change of eco-environment was the main cause to accelerate soil erosion, and the worse environment caused soil erosion to be serious rapidly.

信任水平、感知成本与农户林地流转契约选择

基于福建省319户农户调查数据,采用Tobit、IV-2SLS等计量模型,实证分析信任水平和感知成本对林地流转契约选择的影响,并进一步探究不同流转主体差异、代际差异和感知风险差异在林地流转契约选择方面的异质性。结果表明:1)农户的信任水平和感知成本越高,林地流转时越倾向于选择更长的流转期限和更大的流转面积,转出主体的流转价格越高;信任水平和感知成本的交互项发挥调节作用。2)林地流转契约选择存在代际差异和感知风险差异,在流转期限和流转规模方面,信任水平、感知成本对新生代及感知低风险农户的有效影响更显著;在流转价格方面,信任水平、感知成本对老一代和感知高风险转出农户的影响更显著。据此,建议完善市场机制,激活社会资本,并保持林业政策的稳定性和持久性。

基于机器学习模型的高植被覆盖区浅层滑坡预测

为探究高植被覆盖区浅层滑坡的影响因素并构建最优的滑坡预测模型,该研究以华蓥市山区林地为研究对象,考虑了蓄积量、林分密度、平均树龄、林分类型和红绿植被指数(green-red vegetation index,GRVI)等植被因子,并结合地形地质因素,经过Boruta重要性分析以及共线性诊断,利用Logistic回归模型、广义相加模型、随机森林模型、支持向量机模型和人工神经网络模型等5种机器学习模型构建华蓥市山区林地浅层滑坡预测模型,并结合历史滑坡点检验,提出华蓥市山区林地浅层滑坡的最佳预测模型及高易发性区域的植被特征。结果表明:1)工程地质岩组、距河流距离、距断层距离、林分类型、平均树龄和蓄积量是影响浅层滑坡的主要因子;2)不同因子组合对模型精度有极大的影响,考虑蓄积量、林分密度、平均树龄等植被因子有利于提高模型的预测精度;3)在5种模型中,预测精度最高的模型为随机森林模型,精度可达到95.05%;4)研究区高易发性及以上区域的面积为25.31 km^(2),占研究区总面积的14.79%,低密度(1000~1500株/hm^(2))、高蓄积量(>80 m3/hm^(2))和高树龄(>30 a)是浅层滑坡发生的主要植被特征。该研究结果可为中国高植被覆盖区极端暴雨型滑坡的预警与防控提供科学决策和技术支撑。

Activity Data and Emission Factor for Forestry and Other Land Use Change Subsector to Enhance Carbon Market Policy and Action in Malawi

Activity data and emission factors are critical for estimating greenhouse gas emissions and devising effective climate change mitigation strategies. This study developed the activity data and emission factor in the Forestry and Other Land Use Change (FOLU) subsector in Malawi. The results indicate that “forestland to cropland,” and “wetland to cropland,” were the major land use changes from the year 2000 to the year 2022. The forestland steadily declined at a rate of 13,591 ha (0.5%) per annum. Similarly, grassland declined at the rate of 1651 ha (0.5%) per annum. On the other hand, cropland, wetland, and settlements steadily increased at the rate of 8228 ha (0.14%);5257 ha (0.17%);and 1941 ha (8.1%) per annum, respectively. Furthermore, the results indicate that the “grassland to forestland” changes were higher than the “forestland to grassland” changes, suggesting that forest regrowth was occurring. On the emission factor, the results interestingly indicate that there was a significant increase in carbon sequestration in the FOLU subsector from the year 2011 to 2022. Carbon sequestration increased annually by 13.66 ± 0.17 tCO2 e/ha/yr (4.6%), with an uncertainty of 2.44%. Therefore, it can be concluded that there is potential for a Carbon market in Malawi.

林权改革何以影响农户林业生产投入?

林权改革对完善农村基本经营制度、推动绿色发展和建设生态文明具有重要意义。本文基于全国大样本农户调查数据,运用双重差分模型和中介效应模型实证分析林权改革对农户林业生产投入的影响效果、作用机制及其异质性。研究结果显示,林权改革能够增加农户林业生产投入,并且经过稳健性检验、平行趋势检验、安慰剂检验等一系列检验后此结论依然成立。机制分析结果显示,林权改革通过强化林权安全性直接激励农户增加林业生产投入,尤其对在林权改革中未经历过林地调整的农户家庭,林权改革的林业生产投入激励效应更为明显;林地经营规模、信贷可得性是林权改革间接促进农户林业生产投入增加的重要传导路径。异质性分析结果表明,从林业种植结构来看,林权改革的林业生产投资效应具有明显的生长周期偏好且主要作用于经营生长周期较短的竹林、经济林和速生丰产林,而对经营生长周期较长的一般用材林无政策效果;从空间视角来看,对经济欠发达、山林依赖程度较高的中西部地区家庭,林权改革对农户林业生产投入具有更大的政策激励效应;从农户视角来看,对自然资源禀赋优势更大、林地要素匹配能力更强的中大林地经营规模家庭以及林业生产比较优势更大的低非农化家庭,林权改革提升农户林业生产投入水平的效应更大。结合研究结论,本文提出深化林权改革、优化林地流转和林权抵押贷款政策、强化政策支持的差异化等政策建议。

基于最大熵模型的华蓥山林地浅表层滑坡风险析因

【目的】确定环境变量对林地浅表层滑坡风险预测的相对贡献率,明确影响浅表层滑坡风险的关键植被因素及其减灾区间,探明植被因素与非植被因素对浅表层滑坡风险的耦合效应,为林地浅表层滑坡风险评价和减灾决策制定提供科学依据。【方法】以华蓥山林地为研究对象,选取17个浅表层滑坡影响因子,采用最大熵模型进行林地浅表层滑坡风险模拟,输出各因子对林地浅表层滑坡风险预测的相对贡献率,对比分析考虑或不考虑植被因素条件下林地浅表层滑坡风险对各因子的响应变化。【结果】1)模型精度受试者工作特征曲线检验结果显示,不考虑植被因素的情况下,模型模拟精度为0.887,达到很准确的精度水平;考虑植被因素的情况下,模型模拟精度提升3.1%,为0.915,达到极准确的精度水平。2)工程地质岩组、蓄积量、距断层距离、地形起伏度、高程、绿色比值植被指数、平面曲率和林分类型8个因子对浅表层滑坡风险预测的累计贡献率达80%,其中植被因素对林地浅表层滑坡风险预测具有重要作用,主要体现在蓄积量、植被覆盖度和林分类型3方面。3)植被因素的存在造成浅表层滑坡风险对平面曲率、坡向、高程变异系数、坡度变率和坡面曲率5个变量的响应发生变化:对平面曲率、高程变异系数和剖面曲率所产生的浅表层滑坡风险起削弱作用,削减幅度分别为4.9%、5.9%和8.1%;对坡度变率所产生的浅表层滑坡风险起加剧作用,加剧幅度为10.9%;对坡向所产生的浅表层滑坡风险具有正反2方面作用,加剧和削减幅度分别为12.8%和6.4%。【结论】MaxEnt模型用于林地浅表层滑坡风险模拟具有较高模拟精度,能够直观表达浅表层滑坡风险对各影响因子的响应;利用MaxEnt模型预测林地浅表层滑坡风险时,除了地质、地形、地貌、土壤等常规影响因素外,植被因素也是关键环境变量,其对模拟精度具有重要贡献;植被因素的存在整体上不改变浅表层滑坡风险对其他影响因子的响应趋势,但对于某些非植被因素的极端值所产生的浅表层滑坡风险具有重要影响,呈现出耦合效应,既可能加剧也可能削弱浅表层滑坡风险。

老龄化、要素配置与农户集体林种植决策

基于国家林业和草原局“集体林权制度改革监测”数据与贵州省农户调查数据,实证分析农户老龄化对集体林种植决策的影响,并进一步探究农地经营规模的调节效应与要素配置的中介效应。结果表明:老年农户经济林种植比例明显低于非老年农户,劳动力老龄化显著降低集体林中经济林比例;老年农户经营的农地规模越大,对种植经济林的负向激励就越大,劳动力老龄化对集体林中经济林比例的影响明显受到农地经营规模的调节作用;老年农户分别通过减少林地种植劳动投入和增强林地持有意愿,降低集体林中经济林比例,劳动力老龄化加大农户集体林种植的劳动力约束与林地流转约束,强化农户经济林种植的负向激励。据此,建议推进林地种植社会化服务,加大对新型林业经营主体培育力度,不断优化林地要素配置与林业发展功能区划。

生物炭对林地土壤团聚体稳定性与肥料氮分布的影响

【目的】林地土壤抗侵蚀能力、渗透性及保水性与土壤团聚体结构稳定性紧密相关,氮素的固持与分布直接影响林下植被生长与林地土壤团聚体形成。研究生物炭添加对林地土壤结构稳定性与残留氮素分配的影响,可为增强林地土壤团聚体稳定性、提高土壤氮素固持水平提供参考。【方法】利用福建省林地土壤进行盆栽试验(1年),设置4个处理:对照(CK)、化肥(F)、木炭+化肥(MC)、秸秆炭+化肥(JC),除CK外,化肥及生物炭处理均每盆施用尿素1 g、过磷酸钙2.19 g、氯化钾0.44 g,追肥^(15)N-尿素,共追施5 g,生物炭施用量为每盆140 g。测定不同处理土壤团聚体组成、团聚体稳定性指标、团聚体氮素含量与分布,结合^(15)N示踪技术分析肥料氮在土壤团聚体内的残留特点,揭示生物炭对林地土壤团聚体稳定性与氮素分配的影响。【结果】(1)与F处理相比,MC与JC处理显著提高了土壤大团聚体含量,其中>2 mm土壤团聚体增幅最大,分别增长了108.92%与119.11%;(2)施用生物炭增强了土壤团聚体稳定性,MC与JC处理平均重量直径(MWD)、几何平均直径(GMD)及>0.25 mm大团聚体含量(R>0.25 mm)较F处理均显著提升,分形维数值(D)显著下降,JC处理土壤团聚体稳定性优于MC处理;(3)施用生物炭提高了不同粒径土壤团聚体中全氮含量,MC处理土壤全氮总量高于JC处理,二者的>2 mm团聚体氮素贡献率较F处理分别显著增加了38.09%与69.10%;(4)施用生物炭使>0.25~2 mm粒级团聚体δ^(15)N富集,MC与JC处理土壤肥料氮残留量以>0.25 mm粒级最多,较F处理显著增加了2.25倍与3.89倍,土壤大团聚体中氮肥残留量与团聚体稳定性呈显著正相关。【结论】施用生物炭有利于增强林地土壤团聚体稳定性,减少土壤氮素与肥料淋失,肥料氮在大团聚体中的固持高于微团聚体,秸秆炭对土壤团聚体稳定性提升效果更显著,木炭施用更有利于土壤氮素含量增加。

云南亚热带地区主要林地类型土壤碳含量变化及影响因素研究

[目的]作为陆地生态系统最大的碳库,森林土壤有机碳变化对全球碳循环产生显著影响。通过探究不同林地类型森林土壤碳含量差异及其影响因素,以期为森林碳汇管理提供理论依据。[方法]以澜沧县桉树人工林、思茅松纯林和常绿阔叶林为研究对象,运用单因素、Duncan方差分析和冗余分析法,探究3种林地类型在0~20 cm、20~40 cm及40~60 cm不同土层深度的土壤有机碳含量和密度、碳氮比(C/N)水平及垂直分布变化规律,并揭示其主要影响因素。[结果](1)0~60 cm土层,3种林地类型土壤有机碳含量差异显著。其变化范围为14.89~22.05 g·kg^(-1),高于全国森林土壤有机碳水平,以常绿阔叶林最高(22.05g·kg^(-1));有机碳密度处于3.42~4.12kg·m^(−2)之间,以常绿阔叶林最高(4.12kg·m^(−2));土壤C/N在12.99~13.82之间,以桉树人工林最高(13.82);(2)随着土层加深,3种林地类型土壤有机碳含量、有机碳密度和C/N均呈下降趋势,以常绿阔叶林土壤有机碳含量和密度下降趋势最明显;(3)3种林地类型有机碳含量和密度主要受土壤密度、有机质、全氮、水解性氮和全磷影响,环境和地形因子影响较小;土壤C/N主要影响因子为有机质、p H和坡向,环境因子对其影响较小。[结论]常绿阔叶林和桉树人工林土壤在碳汇方面具有优势,而思茅松纯林碳汇功能较弱。土壤碳含量变化受土壤理化指标影响较大,而受环境和地形因子影响较小。

内蒙古退耕还林工程区林冠覆盖率卫星遥感监测

内蒙古新一轮退耕还林还草工程于2015年启动,是内蒙古生态环境建设恢复的重大举措。本文利用2022年生长季Sentinel-2A影像及地形数据,结合实地测量数据,基于GEE平台采用梯度提升树回归模型(GBRT),对内蒙古新一轮退耕还林工程区林冠覆盖率进行反演分析。结果表明,模型验证决定系数(R^(2))为0.87,均方根误差(RMSE)为0.079,平均绝对误差(MAE)为0.062。内蒙古新一轮退耕还林工程区林冠覆盖率均值为0.147,其分布存在明显的空间差异,受植被配置类型、种植年份和地理环境等因素影响,总体从西向东逐渐递增。利用Sentinel-2A影像和地形数据可以有效地估测退耕还林工程区林冠覆盖率,对低林冠覆盖率区域的反演提供参考。

产权安全对农户林地流转的影响——来自非农就业的调节效应

基于江西集体林区505份农户数据,运用熵值法测算出产权安全综合水平,通过Probit模型和IVprobit模型探讨产权安全影响农户林地流转的作用机制,验证非农就业的收入效应与劳动力转移效应的调节作用。结果表明:产权安全综合水平的提高可促进农户林地转出或转入行为发生,不同维度产权安全水平对林地流转行为的影响具有差异;非农就业通过收入效应弱化了产权安全对林地转出的促进效应。因此,为提高林地产权安全,建议集体林权制度改革要进一步从农户认知层面、政策实际效果提升林地产权安全性,从而促进林地流转;集体林权制度政策的制定需要结合农户家庭生计方式,并进一步完善林权交易平台,畅通林地流转。

紫穗槐接种AM真菌对红壤林下侵蚀劣地的影响研究

为探究植被接种丛枝菌根(AM)真菌对南方红壤区林下侵蚀劣地恢复的影响机制,本研究以马尾松退化林地为对象,设置引种灌木不接菌(S)和引种灌木接菌(S+AMF)两种处理,研究土壤AM真菌群落、土壤肥力及植物生长对紫穗槐(Amorpha fruticosa L.)接种AM真菌的响应。结果表明,接菌一年后,S+AMF处理菌根侵染率(MIR)极显著大于S处理(P<0.001),而接菌三年后MIR在两处理间无显著差异。接菌三年后,与S处理相比,S+AMF处理AM真菌的多样性和丰富度无显著差异,但其在种水平上的网络复杂性有所提高,其中Rhizophagus manihotis、Glomus cf.clarum Att894-7、fungal sp.Kamogawa和Rhizophagus neocaledonicus丰度具有显著性差异;土壤有机碳(SOC)、全氮(TN)、总球囊霉素相关土壤蛋白(TG)、土壤微生物生物量碳(SMBC)和土壤微生物生物量氮(SMBN)含量均显著或极显著提高,土壤团聚体变化不显著;植物叶片中全氮(TN)和全磷(TP)含量以及地上生物量(AGB)均显著或极显著提高,而地下生物量(UGB)显著降低(P<0.05);植物根系构型中,根系总根长(TRL)、总体积(TRV)、比根长(SRL)、比表面积(SSA)和根冠比(R-S R)均显著或极显著降低,而根组织密度(RTD)则极显著提高(P<0.001)。线性回归分析表明,SOC、土壤TN、TG、SMBC、SMBN、AGB与MIR间存在显著或极显著正相关关系,TRL、TRV、R-S R、UGB和MIR间存在显著或极显著负相关关系,说明紫穗槐接种AM真菌能够有效改善土壤肥力,同时改变植物地上地下部的生长情况。本研究结果为林下劣地土壤质量提升和植被恢复提供了技术参考。

第三方不同方式介入流转对转入方林地投入的影响——兼顾产权特征与规模特征的考察

集体林权制度改革的重要政策目标是促进林地流转,以及提高转入方的林地投入水平。实践中基层政府或村委会常作为第三方介入林地流转。文章利用2022年在湖南、贵州、云南三省调研获得的457个林地转入地块样本,采用似不相关回归模型实证检验第三方介入以及第三方不同方式介入流转对转入方林地投入的影响。研究结果显示:(1)第三方介入流转提高了转入方对林地的投入水平,相比于自发流转,第三方中介组织影响转入方资本投入的边际效应为30.71%,第三方行政主导影响转入方资本投入的边际效应为22.31%,第三方中介组织对转入方的林地投入激励作用更明显。(2)从产权实施的角度,相比于第三方行政主导,第三方中介组织降低了林地流转事后发生纠纷概率,边际效应为13.41%,第三方中介组织能更好地强化林地经营权稳定性。(3)从规模匹配的角度,相比于第三方行政主导,第三方中介组织在1%的显著性水平上降低了转入方实际需求与转入面积不匹配的概率,边际效应为17.42%。文章在考虑第三方角色差异的基础上,关注了不同介入方式中产权特征和规模特征的差别。研究结论表明,第三方对林地流转进行适当的干预存在合理性和必要性,但需要平衡政府职能与市场作用的边界,将第三方介入的手段限定在信息传递、协调服务和合约保障等方面。

Spatially explicit changes of forestland in Taiwan Province from 1910 to 2010

Reconstructing long-term changes of forest cover(FC)can provide reliable underlying data for carbon source/sink accounting and simulation of the effects of land use on the climate and environment.Historical maps contain a wealth of forest related information and can provide first-hand data for studying the changes in FC over a long time period.Taking the reconstruction of FC in Taiwan Province from 1910-2010 as the research object,we used map extraction and mining methods to extract forest distribution information from historical forest thematic survey maps,topographic and land cover maps,and reconstructed the spatiotemporal patterns of FC in Taiwan from 1910-2010.The results show that:first,the relative bias of the FC area extracted from the historical maps of Taiwan was below 8%,meaning the FC information contained in maps is highly accurate.Second,the FC of Taiwan has generally declined in the past 100 years.From 1910-2010,the forest area declined from 2.62×10^(6) ha to 2.47×10^(6) ha,with relatively obvious forest reduction having occurred.In stages,the forest area of Taiwan decreased by 26.39×10^(4) ha from 1910 to 1950;and increased by 10.53×10^(4) ha during the period 1950-2010.Forest reduction was obvious during the Japanese occupation period,while forest increase was remarkable during the Kuomintang period.Third,during the study period,the total area of patches maintained as forests was 2.17×10^(6) ha with little change in the overall pattern,and forests were mainly distributed in the mountain regions.The loss of forest mainly occurred in the plains,with expanding forest areas mainly in the mountain regions at high elevations and on steep slopes.Fourth,land clearing for agriculture during the Japanese occupation period has been the important driver of forest reduction in Taiwan over the past century.After retreated to Taiwan,the Kuomintang government introduced effective and remarkable reforms that led to effective restoration of forest vegetation in many areas where forests had previously disappeared.

中国集体林权制度改革:2012年以来的新进展与40余年的典型事实分析

集体林权制度改革(下文简称集体林改)是中国改革开放以来集体林区改革与发展的主旋律。40余年来,中国政府启动了多轮集体林改,取得了较好进展。在已有研究基础上,基于国家林业和草原局发布的典型案例、国家林业和草原局发展研究中心集体林权研究团队的实地调研访谈案例,文章采用叙事分析法,重点梳理了2012年以来集体林改新进展,界定与分析40余年的集体林改典型事实。研究结果显示:(1)集体林地“三权分置”明确了新时代集体林改的方向与基本思路,集体林地“三权分置”与金融创新促进了适度规模经营和林业生态产品价值的实现;(2)40余年的集体林改典型事实表现为集体林权呈现出多样性、背景条件至关重要、经济逻辑与政治逻辑并重、频繁产权制度变迁难以形成稳定经营预期、在规模大与小之间来回摆动、制度间匹配差、长短期绩效差异明显、信息不对称严重、市场和政府边界不清等特征。文章可能的边际学术贡献为:(1)采用叙事分析法研究了2012年以来集体林改的动力机制及其新进展;(2)明确了40余年来集体林改的典型事实。在后续集体林改中,应稳步推进,增强集体林经营主体的林改成果获得感,实现生态美和百姓富的有机统一。

泸定地震对土壤物理性质及碳储量的影响

2022年9月5日,四川省甘孜藏族自治州泸定县发生6.8级地震,造成周边区域水土流失加剧,生态状况急剧恶化。本文以此次泸定地震影响产生山体滑坡的林地作为研究对象,以附近未受地震影响且林分结构相近的林地作为对照,分析地震对林地土壤物理性质及碳储量的影响。结果表明,0~5 cm和>5~10 cm土层均表现为滑坡后土壤容重高于未滑坡土壤,碳储量均低于未滑坡土壤。0~5 cm表层土壤毛管持水量、毛管孔隙度均表现为滑坡后大于未滑坡土壤,非毛管孔隙度则相反。综上所述,地震产生的滑坡会对土壤的物理结构产生影响,进而减少土壤的有机碳储量。

生态因子对林地参和农田参质量差异的影响

生态环境是导致林地参和农田参质量差异的重要影响因素,以林地参和农田参中人参皂苷含量为指标分析其质量差异,测定根际土壤理化性质,并对测定结果进行相关性、多元逐步回归、变异系数、偏最小二乘法判别和层次分析法综合评价。结果显示,林地参和农田参中人参皂苷含量及其根际土壤理化性质差异显著;变异系数分析显示,农田参中大部分生态因子指标变异系数大于林地参;相关性、多元逐步回归和偏最小二乘法判别分析显示最高气温、最低气温、pH、碱解氮、有效磷等土壤因子与人参皂苷的相关性显著;层次分析结果显示,不同栽培模式的土壤质量差异显著。多项统计结果表明,最高气温、最低气温、pH是影响人参皂苷含量的主要因子,其次为碱解氮、有效磷和土壤含水量。以上结果表明,最高气温、最低气温、pH、碱解氮、有效磷和土壤含水量是影响林地参和农田参质量的重要原因,研究结果为解析人参质量形成和种植生产提供理论依据。