School of Geography, University of Leeds, Leeds LS2 9JT, UK ; School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK.
School of Geography, University of Leeds, Leeds LS2 9JT, UK.
Carbon Balance Manag. 2014 Apr 28;9:2. doi: 10.1186/1750-0680-9-2. eCollection 2014.
The carbon stored in vegetation varies across tropical landscapes due to a complex mix of climatic and edaphic variables, as well as direct human interventions such as deforestation and forest degradation. Mapping and monitoring this variation is essential if policy developments such as REDD+ (Reducing Emissions from Deforestation and Forest Degradation) are to be known to have succeeded or failed.
We produce a map of carbon storage across the watershed of the Tanzanian Eastern Arc Mountains (33.9 million ha) using 1,611 forest inventory plots, and correlations with associated climate, soil and disturbance data. As expected, tropical forest stores more carbon per hectare (182 Mg C ha(-1)) than woody savanna (51 Mg C ha(-1)). However, woody savanna is the largest aggregate carbon store, with 0.49 Pg C over 9.6 million ha. We estimate the whole landscape stores 1.3 Pg C, significantly higher than most previous estimates for the region. The 95% Confidence Interval for this method (0.9 to 3.2 Pg C) is larger than simpler look-up table methods (1.5 to 1.6 Pg C), suggesting simpler methods may underestimate uncertainty. Using a small number of inventory plots with two censuses (n = 43) to assess changes in carbon storage, and applying the same mapping procedures, we found that carbon storage in the tree-dominated ecosystems has decreased, though not significantly, at a mean rate of 1.47 Mg C ha(-1) yr(-1) (c. 2% of the stocks of carbon per year).
The most influential variables on carbon storage in the region are anthropogenic, particularly historical logging, as noted by the largest coefficient of explanatory variable on the response variable. Of the non-anthropogenic factors, a negative correlation with air temperature and a positive correlation with water availability dominate, having smaller p-values than historical logging but also smaller influence. High carbon storage is typically found far from the commercial capital, in locations with a low monthly temperature range, without a strong dry season, and in areas that have not suffered from historical logging. The results imply that policy interventions could retain carbon stored in vegetation and likely successfully slow or reverse carbon emissions.
由于气候和土壤等多种变量的复杂混合，以及森林砍伐和森林退化等直接人为干预，热带景观中的植被所储存的碳会发生变化。如果要了解 REDD+（减少毁林和森林退化所致排放）等政策的发展是成功还是失败，就必须对这种变化进行测绘和监测。
我们利用坦桑尼亚东部弧形山脉流域的 1611 个森林清查样本来生成一张碳储量图，并与相关的气候、土壤和干扰数据进行了关联。不出所料，热带森林每公顷的碳储量（182 Mg C ha-1）高于木质稀树草原（51 Mg C ha-1）。然而，木质稀树草原是最大的碳储量，960 万公顷的碳储量为 0.49 Pg C。我们估计整个景观的碳储量为 1.3 Pg C，明显高于该地区的大多数先前估计值。这种方法的 95%置信区间（0.9 到 3.2 Pg C）大于更简单的查表方法（1.5 到 1.6 Pg C），这表明更简单的方法可能会低估不确定性。我们使用两次清查（n = 43）的少数清查样本来评估碳储量的变化，并应用相同的测绘程序，发现树木占主导地位的生态系统的碳储量已经减少，尽管幅度不大，平均每年减少 1.47 Mg C ha-1（每年碳储量的 2%）。
对该地区碳储量影响最大的变量是人为因素，特别是历史上的伐木活动，这是响应变量中解释变量的最大系数所表明的。在非人为因素中，与空气温度呈负相关，与水分供应呈正相关，其 p 值小于历史上的伐木活动，但影响也较小。高碳储量通常出现在远离商业首都的地方，那里的月温差较小，旱季不强烈，而且没有遭受过历史上的伐木活动。结果表明，政策干预措施可以保留植被中的碳储量，并可能成功地减缓或逆转碳排放。
