2) In a dynamical system, what is an equilibrium? A stable equilibrium? An unstable equilibrium?

PART B. SCIENTIFIC REASONING每題10分 Coral Reef Ecosystems: Peter J. Mumby and collaborators (2007) analyzed and modeled mechanisms causing the contemporary decline of Caribbean corals. They showed that macroalgal growth has a negative effect on coral growth and that the growth of macroalgae is, itself, controlled by herbivores such as urchins (Diadem(A) and parrotfishes. Authors modeled the system at high and low levels of grazing (Figure 1). Figure 1. Phase planes showing equilibrium covers of macroalgae and corals and trajectories over time for simulations at a high level of grazing (a) or a low level of grazing (b). Adapted from Mumby et al. (2007). The same model allows representing the % of coral cover as a function of the grazing (Figure 2). The trajectory of reefs in Jamaica such as observed between the 1970s and the 1990s is overlapped using blue arrows in the figure. Figure 2. Stable and unstable equilibria for Caribbean coral reefs. Stable and unsrable equitibria are denored by spriate dates, rep solid and open squares, respectively. Bhue lines. marked with approp epresent model predictions of the trajectory of reefs in Jamaica (see also Figure 3). Adapted from Mumby et al. (2007). Figure 3 represents the changes in coral cover (%) since the 1970s with the indication of the events that could have influenced those changes. Figure 3. Comparison between model predictions and empirical data for the trajectory of sructurally complex forereefs in Jamaica at a depth of 10 m. The model was run with an algal coral overgr overgrowth rate of 14 cm2 yr1. Diadema is a genus of sea urchin and an important grazer on Caribbean reefs. Adapied from Mumby et al. (2007). Reference: Mumby PJ. Hastings A. Edwards, HJ (2007) Thresholds and the resilience of Caribbean coral reefs. Nature 450. 98-101. https://doi.org/10.1038/nature06252

QUESTIONS 1) According to your knowledge, why is it important to maintain coral reefs in good conditions?

3) Copy the figure 1 (or use Figure 1-1 without the trajectories in red), and represent schematically the trajectories of the system starting at points 1, 2, 3, 4, 5, 6, 7, 8. What is the effect of reducing herbivory (grazing)?

4) Copy the figure 2 (or use Figure 2-1 without the model predictions of the reefs in Jamaic(A) and represent the change in coral cover starting at points a, b, c, d, e, f. What is the particularity of cases c and d (within the grey area)? How do we call this situation? What's happen when we increase or decrease the grazing?

5) Combining the information in figures 2 and 3, describe the changes in coral cover and the suggested causes of those changes. What will you suggest to increase coral cover?

四、陸域與水域生態系統的初級生產力受限因子有所差異。陸域主要受到溫 度與水分供應的制約，養分相對次要；而在水域中，初級生產力則更顯 著地受限於養分供應，同時光穿透度也影響生產力的表現。請比較並論 述陸域與水域初級生產力的限制因子差異，並說明此差異對生態系統功 能與全球碳循環的潛在影響。（25 分）

三、「滅絕電梯」假說認為，氣候變遷將迫使山區物種不斷向高海拔遷移， 最終因無處可退而加速滅絕。然而新近發表研究分析全球 23 個山區及 數千物種資料，發現山頂物種未顯著縮減，反而部分低海拔與分布狹窄 的物種呈現擴張，物種間重疊增加。請根據上述研究結果，分析其對山 區生物多樣性保育與未來研究方向的啟示。（25 分）

二、「調節類生態系服務」（Regulating Ecosystem Services）指的是生態系統 透過自然過程所提供的調節功能，對人類社會與環境穩定具有重要意 義。請舉一臺灣藍碳生態系統為例，詳細說明該生態系潛在之調節類生 態系服務，以及該生態系服務之價值評估方法。（25 分）

一、2010 年《生物多樣性公約》（CBD）在愛知目標 11 中首次提出 Other Effective area-based Conservation Measures（OECMs）的概念，又稱為「其 他有效保育措施之區域」或「保育共生地」 ，可補自然保護區之不足。其 認定條件之一是對重要生物多樣性現地保育具長期且持續有效之貢獻。 請詳述「重要生物多樣性」之意涵及認定標準。（25 分）

四、有學者依據歷史文獻與早期標本採集紀錄，主張臺灣西海岸現存的紅樹 林多為人為引入與栽植，可能來自先民自中國福建、廣東移植，或政府 於沿海地區推動造林所致，並非臺灣原生植物，因而缺乏原生分布的歷 史紀錄。請評析此一觀點之證據力，並論述其在生態學研究與自然保育 爭議中的意涵。（25 分）

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